text: /*
   * Copyright (C) 2007 Oracle.  All rights reserved.
   *
   * This program is free software; you can redistribute it and/or
   * modify it under the terms of the GNU General Public
   * License v2 as published by the Free Software Foundation.
   *
   * This program is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   * General Public License for more details.
   *
   * You should have received a copy of the GNU General Public
   * License along with this program; if not, write to the
   * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
   * Boston, MA 021110-1307, USA.
   */
  
  #include <linux/kernel.h>
  #include <linux/bio.h>
  #include <linux/buffer_head.h>
  #include <linux/file.h>
  #include <linux/fs.h>
  #include <linux/fsnotify.h>
  #include <linux/pagemap.h>
  #include <linux/highmem.h>
  #include <linux/time.h>
  #include <linux/init.h>
  #include <linux/string.h>
  #include <linux/backing-dev.h>
  #include <linux/mount.h>
  #include <linux/mpage.h>
  #include <linux/namei.h>
  #include <linux/swap.h>
  #include <linux/writeback.h>
  #include <linux/compat.h>
  #include <linux/bit_spinlock.h>
  #include <linux/security.h>
  #include <linux/xattr.h>
  #include <linux/mm.h>
  #include <linux/slab.h>
  #include <linux/blkdev.h>
  #include <linux/uuid.h>
  #include <linux/btrfs.h>
  #include <linux/uaccess.h>
  #include "ctree.h"
  #include "disk-io.h"
  #include "transaction.h"
  #include "btrfs_inode.h"
  #include "print-tree.h"
  #include "volumes.h"
  #include "locking.h"
  #include "inode-map.h"
  #include "backref.h"
  #include "rcu-string.h"
  #include "send.h"
  #include "dev-replace.h"
  #include "props.h"
  #include "sysfs.h"
  #include "qgroup.h"
  #include "tree-log.h"
  #include "compression.h"
  
  #ifdef CONFIG_64BIT
  /* If we have a 32-bit userspace and 64-bit kernel, then the UAPI
   * structures are incorrect, as the timespec structure from userspace
   * is 4 bytes too small. We define these alternatives here to teach
   * the kernel about the 32-bit struct packing.
   */
  struct btrfs_ioctl_timespec_32 {
  	__u64 sec;
  	__u32 nsec;
  } __attribute__ ((__packed__));
  
  struct btrfs_ioctl_received_subvol_args_32 {
  	char	uuid[BTRFS_UUID_SIZE];	/* in */
  	__u64	stransid;		/* in */
  	__u64	rtransid;		/* out */
  	struct btrfs_ioctl_timespec_32 stime; /* in */
  	struct btrfs_ioctl_timespec_32 rtime; /* out */
  	__u64	flags;			/* in */
  	__u64	reserved[16];		/* in */
  } __attribute__ ((__packed__));
  
  #define BTRFS_IOC_SET_RECEIVED_SUBVOL_32 _IOWR(BTRFS_IOCTL_MAGIC, 37, \
  				struct btrfs_ioctl_received_subvol_args_32)
  #endif
  
  
  static int btrfs_clone(struct inode *src, struct inode *inode,
  		       u64 off, u64 olen, u64 olen_aligned, u64 destoff,
  		       int no_time_update);
  
  /* Mask out flags that are inappropriate for the given type of inode. */
  static inline __u32 btrfs_mask_flags(umode_t mode, __u32 flags)
  {
  	if (S_ISDIR(mode))
  		return flags;
  	else if (S_ISREG(mode))
  		return flags & ~FS_DIRSYNC_FL;
  	else
  		return flags & (FS_NODUMP_FL | FS_NOATIME_FL);
  }
  
  /*
   * Export inode flags to the format expected by the FS_IOC_GETFLAGS ioctl.
   */
  static unsigned int btrfs_flags_to_ioctl(unsigned int flags)
  {
  	unsigned int iflags = 0;
  
  	if (flags & BTRFS_INODE_SYNC)
  		iflags |= FS_SYNC_FL;
  	if (flags & BTRFS_INODE_IMMUTABLE)
  		iflags |= FS_IMMUTABLE_FL;
  	if (flags & BTRFS_INODE_APPEND)
  		iflags |= FS_APPEND_FL;
  	if (flags & BTRFS_INODE_NODUMP)
  		iflags |= FS_NODUMP_FL;
  	if (flags & BTRFS_INODE_NOATIME)
  		iflags |= FS_NOATIME_FL;
  	if (flags & BTRFS_INODE_DIRSYNC)
  		iflags |= FS_DIRSYNC_FL;
  	if (flags & BTRFS_INODE_NODATACOW)
  		iflags |= FS_NOCOW_FL;
  
  	if (flags & BTRFS_INODE_NOCOMPRESS)
  		iflags |= FS_NOCOMP_FL;
  	else if (flags & BTRFS_INODE_COMPRESS)
  		iflags |= FS_COMPR_FL;
  
  	return iflags;
  }
  
  /*
   * Update inode->i_flags based on the btrfs internal flags.
   */
  void btrfs_update_iflags(struct inode *inode)
  {
  	struct btrfs_inode *ip = BTRFS_I(inode);
  	unsigned int new_fl = 0;
  
  	if (ip->flags & BTRFS_INODE_SYNC)
  		new_fl |= S_SYNC;
  	if (ip->flags & BTRFS_INODE_IMMUTABLE)
  		new_fl |= S_IMMUTABLE;
  	if (ip->flags & BTRFS_INODE_APPEND)
  		new_fl |= S_APPEND;
  	if (ip->flags & BTRFS_INODE_NOATIME)
  		new_fl |= S_NOATIME;
  	if (ip->flags & BTRFS_INODE_DIRSYNC)
  		new_fl |= S_DIRSYNC;
  
  	set_mask_bits(&inode->i_flags,
  		      S_SYNC | S_APPEND | S_IMMUTABLE | S_NOATIME | S_DIRSYNC,
  		      new_fl);
  }
  
  static int btrfs_ioctl_getflags(struct file *file, void __user *arg)
  {
  	struct btrfs_inode *ip = BTRFS_I(file_inode(file));
  	unsigned int flags = btrfs_flags_to_ioctl(ip->flags);
  
  	if (copy_to_user(arg, &flags, sizeof(flags)))
  		return -EFAULT;
  	return 0;
  }
  
  static int check_flags(unsigned int flags)
  {
  	if (flags & ~(FS_IMMUTABLE_FL | FS_APPEND_FL | \
  		      FS_NOATIME_FL | FS_NODUMP_FL | \
  		      FS_SYNC_FL | FS_DIRSYNC_FL | \
  		      FS_NOCOMP_FL | FS_COMPR_FL |
  		      FS_NOCOW_FL))
  		return -EOPNOTSUPP;
  
  	if ((flags & FS_NOCOMP_FL) && (flags & FS_COMPR_FL))
  		return -EINVAL;
  
  	return 0;
  }
  
  static int btrfs_ioctl_setflags(struct file *file, void __user *arg)
  {
  	struct inode *inode = file_inode(file);
  	struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
  	struct btrfs_inode *ip = BTRFS_I(inode);
  	struct btrfs_root *root = ip->root;
  	struct btrfs_trans_handle *trans;
  	unsigned int flags, oldflags;
  	int ret;
  	u64 ip_oldflags;
  	unsigned int i_oldflags;
  	umode_t mode;
  
  	if (!inode_owner_or_capable(inode))
  		return -EPERM;
  
  	if (btrfs_root_readonly(root))
  		return -EROFS;
  
  	if (copy_from_user(&flags, arg, sizeof(flags)))
  		return -EFAULT;
  
  	ret = check_flags(flags);
  	if (ret)
  		return ret;
  
  	ret = mnt_want_write_file(file);
  	if (ret)
  		return ret;
  
  	inode_lock(inode);
  
  	ip_oldflags = ip->flags;
  	i_oldflags = inode->i_flags;
  	mode = inode->i_mode;
  
  	flags = btrfs_mask_flags(inode->i_mode, flags);
  	oldflags = btrfs_flags_to_ioctl(ip->flags);
  	if ((flags ^ oldflags) & (FS_APPEND_FL | FS_IMMUTABLE_FL)) {
  		if (!capable(CAP_LINUX_IMMUTABLE)) {
  			ret = -EPERM;
  			goto out_unlock;
  		}
  	}
  
  	if (flags & FS_SYNC_FL)
  		ip->flags |= BTRFS_INODE_SYNC;
  	else
  		ip->flags &= ~BTRFS_INODE_SYNC;
  	if (flags & FS_IMMUTABLE_FL)
  		ip->flags |= BTRFS_INODE_IMMUTABLE;
  	else
  		ip->flags &= ~BTRFS_INODE_IMMUTABLE;
  	if (flags & FS_APPEND_FL)
  		ip->flags |= BTRFS_INODE_APPEND;
  	else
  		ip->flags &= ~BTRFS_INODE_APPEND;
  	if (flags & FS_NODUMP_FL)
  		ip->flags |= BTRFS_INODE_NODUMP;
  	else
  		ip->flags &= ~BTRFS_INODE_NODUMP;
  	if (flags & FS_NOATIME_FL)
  		ip->flags |= BTRFS_INODE_NOATIME;
  	else
  		ip->flags &= ~BTRFS_INODE_NOATIME;
  	if (flags & FS_DIRSYNC_FL)
  		ip->flags |= BTRFS_INODE_DIRSYNC;
  	else
  		ip->flags &= ~BTRFS_INODE_DIRSYNC;
  	if (flags & FS_NOCOW_FL) {
  		if (S_ISREG(mode)) {
  			/*
  			 * It's safe to turn csums off here, no extents exist.
  			 * Otherwise we want the flag to reflect the real COW
  			 * status of the file and will not set it.
  			 */
  			if (inode->i_size == 0)
  				ip->flags |= BTRFS_INODE_NODATACOW
  					   | BTRFS_INODE_NODATASUM;
  		} else {
  			ip->flags |= BTRFS_INODE_NODATACOW;
  		}
  	} else {
  		/*
  		 * Revert back under same assumptions as above
  		 */
  		if (S_ISREG(mode)) {
  			if (inode->i_size == 0)
  				ip->flags &= ~(BTRFS_INODE_NODATACOW
  				             | BTRFS_INODE_NODATASUM);
  		} else {
  			ip->flags &= ~BTRFS_INODE_NODATACOW;
  		}
  	}
  
  	/*
  	 * The COMPRESS flag can only be changed by users, while the NOCOMPRESS
  	 * flag may be changed automatically if compression code won't make
  	 * things smaller.
  	 */
  	if (flags & FS_NOCOMP_FL) {
  		ip->flags &= ~BTRFS_INODE_COMPRESS;
  		ip->flags |= BTRFS_INODE_NOCOMPRESS;
  
  		ret = btrfs_set_prop(inode, "btrfs.compression", NULL, 0, 0);
  		if (ret && ret != -ENODATA)
  			goto out_drop;
  	} else if (flags & FS_COMPR_FL) {
  		const char *comp;
  
  		ip->flags |= BTRFS_INODE_COMPRESS;
  		ip->flags &= ~BTRFS_INODE_NOCOMPRESS;
  
  		if (fs_info->compress_type == BTRFS_COMPRESS_LZO)
  			comp = "lzo";
  		else if (fs_info->compress_type == BTRFS_COMPRESS_ZLIB)
  			comp = "zlib";
  		else
  			comp = "zstd";
  		ret = btrfs_set_prop(inode, "btrfs.compression",
  				     comp, strlen(comp), 0);
  		if (ret)
  			goto out_drop;
  
  	} else {
  		ret = btrfs_set_prop(inode, "btrfs.compression", NULL, 0, 0);
  		if (ret && ret != -ENODATA)
  			goto out_drop;
  		ip->flags &= ~(BTRFS_INODE_COMPRESS | BTRFS_INODE_NOCOMPRESS);
  	}
  
  	trans = btrfs_start_transaction(root, 1);
  	if (IS_ERR(trans)) {
  		ret = PTR_ERR(trans);
  		goto out_drop;
  	}
  
  	btrfs_update_iflags(inode);
  	inode_inc_iversion(inode);
  	inode->i_ctime = current_time(inode);
  	ret = btrfs_update_inode(trans, root, inode);
  
  	btrfs_end_transaction(trans);
   out_drop:
  	if (ret) {
  		ip->flags = ip_oldflags;
  		inode->i_flags = i_oldflags;
  	}
  
   out_unlock:
  	inode_unlock(inode);
  	mnt_drop_write_file(file);
  	return ret;
  }
  
  static int btrfs_ioctl_getversion(struct file *file, int __user *arg)
  {
  	struct inode *inode = file_inode(file);
  
  	return put_user(inode->i_generation, arg);
  }
  
  static noinline int btrfs_ioctl_fitrim(struct file *file, void __user *arg)
  {
  	struct inode *inode = file_inode(file);
  	struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
  	struct btrfs_device *device;
  	struct request_queue *q;
  	struct fstrim_range range;
  	u64 minlen = ULLONG_MAX;
  	u64 num_devices = 0;
  	int ret;
  
  	if (!capable(CAP_SYS_ADMIN))
  		return -EPERM;
  
  	rcu_read_lock();
  	list_for_each_entry_rcu(device, &fs_info->fs_devices->devices,
  				dev_list) {
  		if (!device->bdev)
  			continue;
  		q = bdev_get_queue(device->bdev);
  		if (blk_queue_discard(q)) {
  			num_devices++;
  			minlen = min_t(u64, q->limits.discard_granularity,
  				     minlen);
  		}
  	}
  	rcu_read_unlock();
  
  	if (!num_devices)
  		return -EOPNOTSUPP;
  	if (copy_from_user(&range, arg, sizeof(range)))
  		return -EFAULT;
  
  	/*
  	 * NOTE: Don't truncate the range using super->total_bytes.  Bytenr of
  	 * block group is in the logical address space, which can be any
  	 * sectorsize aligned bytenr in  the range [0, U64_MAX].
  	 */
  	if (range.len < fs_info->sb->s_blocksize)
  		return -EINVAL;
  
  	range.minlen = max(range.minlen, minlen);
  	ret = btrfs_trim_fs(fs_info, &range);
  	if (ret < 0)
  		return ret;
  
  	if (copy_to_user(arg, &range, sizeof(range)))
  		return -EFAULT;
  
  	return 0;
  }
  
  int btrfs_is_empty_uuid(u8 *uuid)
  {
  	int i;
  
  	for (i = 0; i < BTRFS_UUID_SIZE; i++) {
  		if (uuid[i])
  			return 0;
  	}
  	return 1;
  }
  
  static noinline int create_subvol(struct inode *dir,
  				  struct dentry *dentry,
  				  const char *name, int namelen,
  				  u64 *async_transid,
  				  struct btrfs_qgroup_inherit *inherit)
  {
  	struct btrfs_fs_info *fs_info = btrfs_sb(dir->i_sb);
  	struct btrfs_trans_handle *trans;
  	struct btrfs_key key;
  	struct btrfs_root_item *root_item;
  	struct btrfs_inode_item *inode_item;
  	struct extent_buffer *leaf;
  	struct btrfs_root *root = BTRFS_I(dir)->root;
  	struct btrfs_root *new_root;
  	struct btrfs_block_rsv block_rsv;
  	struct timespec cur_time = current_time(dir);
  	struct inode *inode;
  	int ret;
  	int err;
  	u64 objectid;
  	u64 new_dirid = BTRFS_FIRST_FREE_OBJECTID;
  	u64 index = 0;
  	u64 qgroup_reserved;
  	uuid_le new_uuid;
  
  	root_item = kzalloc(sizeof(*root_item), GFP_KERNEL);
  	if (!root_item)
  		return -ENOMEM;
  
  	ret = btrfs_find_free_objectid(fs_info->tree_root, &objectid);
  	if (ret)
  		goto fail_free;
  
  	/*
  	 * Don't create subvolume whose level is not zero. Or qgroup will be
  	 * screwed up since it assumes subvolume qgroup's level to be 0.
  	 */
  	if (btrfs_qgroup_level(objectid)) {
  		ret = -ENOSPC;
  		goto fail_free;
  	}
  
  	btrfs_init_block_rsv(&block_rsv, BTRFS_BLOCK_RSV_TEMP);
  	/*
  	 * The same as the snapshot creation, please see the comment
  	 * of create_snapshot().
  	 */
  	ret = btrfs_subvolume_reserve_metadata(root, &block_rsv,
  					       8, &qgroup_reserved, false);
  	if (ret)
  		goto fail_free;
  
  	trans = btrfs_start_transaction(root, 0);
  	if (IS_ERR(trans)) {
  		ret = PTR_ERR(trans);
  		btrfs_subvolume_release_metadata(fs_info, &block_rsv);
  		goto fail_free;
  	}
  	trans->block_rsv = &block_rsv;
  	trans->bytes_reserved = block_rsv.size;
  
  	ret = btrfs_qgroup_inherit(trans, fs_info, 0, objectid, inherit);
  	if (ret)
  		goto fail;
  
  	leaf = btrfs_alloc_tree_block(trans, root, 0, objectid, NULL, 0, 0, 0);
  	if (IS_ERR(leaf)) {
  		ret = PTR_ERR(leaf);
  		goto fail;
  	}
  
  	memzero_extent_buffer(leaf, 0, sizeof(struct btrfs_header));
  	btrfs_set_header_bytenr(leaf, leaf->start);
  	btrfs_set_header_generation(leaf, trans->transid);
  	btrfs_set_header_backref_rev(leaf, BTRFS_MIXED_BACKREF_REV);
  	btrfs_set_header_owner(leaf, objectid);
  
  	write_extent_buffer_fsid(leaf, fs_info->fsid);
  	write_extent_buffer_chunk_tree_uuid(leaf, fs_info->chunk_tree_uuid);
  	btrfs_mark_buffer_dirty(leaf);
  
  	inode_item = &root_item->inode;
  	btrfs_set_stack_inode_generation(inode_item, 1);
  	btrfs_set_stack_inode_size(inode_item, 3);
  	btrfs_set_stack_inode_nlink(inode_item, 1);
  	btrfs_set_stack_inode_nbytes(inode_item,
  				     fs_info->nodesize);
  	btrfs_set_stack_inode_mode(inode_item, S_IFDIR | 0755);
  
  	btrfs_set_root_flags(root_item, 0);
  	btrfs_set_root_limit(root_item, 0);
  	btrfs_set_stack_inode_flags(inode_item, BTRFS_INODE_ROOT_ITEM_INIT);
  
  	btrfs_set_root_bytenr(root_item, leaf->start);
  	btrfs_set_root_generation(root_item, trans->transid);
  	btrfs_set_root_level(root_item, 0);
  	btrfs_set_root_refs(root_item, 1);
  	btrfs_set_root_used(root_item, leaf->len);
  	btrfs_set_root_last_snapshot(root_item, 0);
  
  	btrfs_set_root_generation_v2(root_item,
  			btrfs_root_generation(root_item));
  	uuid_le_gen(&new_uuid);
  	memcpy(root_item->uuid, new_uuid.b, BTRFS_UUID_SIZE);
  	btrfs_set_stack_timespec_sec(&root_item->otime, cur_time.tv_sec);
  	btrfs_set_stack_timespec_nsec(&root_item->otime, cur_time.tv_nsec);
  	root_item->ctime = root_item->otime;
  	btrfs_set_root_ctransid(root_item, trans->transid);
  	btrfs_set_root_otransid(root_item, trans->transid);
  
  	btrfs_tree_unlock(leaf);
  	free_extent_buffer(leaf);
  	leaf = NULL;
  
  	btrfs_set_root_dirid(root_item, new_dirid);
  
  	key.objectid = objectid;
  	key.offset = 0;
  	key.type = BTRFS_ROOT_ITEM_KEY;
  	ret = btrfs_insert_root(trans, fs_info->tree_root, &key,
  				root_item);
  	if (ret)
  		goto fail;
  
  	key.offset = (u64)-1;
  	new_root = btrfs_read_fs_root_no_name(fs_info, &key);
  	if (IS_ERR(new_root)) {
  		ret = PTR_ERR(new_root);
  		btrfs_abort_transaction(trans, ret);
  		goto fail;
  	}
  
  	btrfs_record_root_in_trans(trans, new_root);
  
  	ret = btrfs_create_subvol_root(trans, new_root, root, new_dirid);
  	if (ret) {
  		/* We potentially lose an unused inode item here */
  		btrfs_abort_transaction(trans, ret);
  		goto fail;
  	}
  
  	mutex_lock(&new_root->objectid_mutex);
  	new_root->highest_objectid = new_dirid;
  	mutex_unlock(&new_root->objectid_mutex);
  
  	/*
  	 * insert the directory item
  	 */
  	ret = btrfs_set_inode_index(BTRFS_I(dir), &index);
  	if (ret) {
  		btrfs_abort_transaction(trans, ret);
  		goto fail;
  	}
  
  	ret = btrfs_insert_dir_item(trans, root,
  				    name, namelen, BTRFS_I(dir), &key,
  				    BTRFS_FT_DIR, index);
  	if (ret) {
  		btrfs_abort_transaction(trans, ret);
  		goto fail;
  	}
  
  	btrfs_i_size_write(BTRFS_I(dir), dir->i_size + namelen * 2);
  	ret = btrfs_update_inode(trans, root, dir);
  	BUG_ON(ret);
  
  	ret = btrfs_add_root_ref(trans, fs_info,
  				 objectid, root->root_key.objectid,
  				 btrfs_ino(BTRFS_I(dir)), index, name, namelen);
  	BUG_ON(ret);
  
  	ret = btrfs_uuid_tree_add(trans, fs_info, root_item->uuid,
  				  BTRFS_UUID_KEY_SUBVOL, objectid);
  	if (ret)
  		btrfs_abort_transaction(trans, ret);
  
  fail:
  	kfree(root_item);
  	trans->block_rsv = NULL;
  	trans->bytes_reserved = 0;
  	btrfs_subvolume_release_metadata(fs_info, &block_rsv);
  
  	if (async_transid) {
  		*async_transid = trans->transid;
  		err = btrfs_commit_transaction_async(trans, 1);
  		if (err)
  			err = btrfs_commit_transaction(trans);
  	} else {
  		err = btrfs_commit_transaction(trans);
  	}
  	if (err && !ret)
  		ret = err;
  
  	if (!ret) {
  		inode = btrfs_lookup_dentry(dir, dentry);
  		if (IS_ERR(inode))
  			return PTR_ERR(inode);
  		d_instantiate(dentry, inode);
  	}
  	return ret;
  
  fail_free:
  	kfree(root_item);
  	return ret;
  }
  
  static void btrfs_wait_for_no_snapshotting_writes(struct btrfs_root *root)
  {
  	s64 writers;
  	DEFINE_WAIT(wait);
  
  	do {
  		prepare_to_wait(&root->subv_writers->wait, &wait,
  				TASK_UNINTERRUPTIBLE);
  
  		writers = percpu_counter_sum(&root->subv_writers->counter);
  		if (writers)
  			schedule();
  
  		finish_wait(&root->subv_writers->wait, &wait);
  	} while (writers);
  }
  
  static int create_snapshot(struct btrfs_root *root, struct inode *dir,
  			   struct dentry *dentry,
  			   u64 *async_transid, bool readonly,
  			   struct btrfs_qgroup_inherit *inherit)
  {
  	struct btrfs_fs_info *fs_info = btrfs_sb(dir->i_sb);
  	struct inode *inode;
  	struct btrfs_pending_snapshot *pending_snapshot;
  	struct btrfs_trans_handle *trans;
  	int ret;
  
  	if (!test_bit(BTRFS_ROOT_REF_COWS, &root->state))
  		return -EINVAL;
  
  	pending_snapshot = kzalloc(sizeof(*pending_snapshot), GFP_KERNEL);
  	if (!pending_snapshot)
  		return -ENOMEM;
  
  	pending_snapshot->root_item = kzalloc(sizeof(struct btrfs_root_item),
  			GFP_KERNEL);
  	pending_snapshot->path = btrfs_alloc_path();
  	if (!pending_snapshot->root_item || !pending_snapshot->path) {
  		ret = -ENOMEM;
  		goto free_pending;
  	}
  
  	atomic_inc(&root->will_be_snapshotted);
  	smp_mb__after_atomic();
  	btrfs_wait_for_no_snapshotting_writes(root);
  
  	ret = btrfs_start_delalloc_inodes(root, 0);
  	if (ret)
  		goto dec_and_free;
  
  	btrfs_wait_ordered_extents(root, U64_MAX, 0, (u64)-1);
  
  	btrfs_init_block_rsv(&pending_snapshot->block_rsv,
  			     BTRFS_BLOCK_RSV_TEMP);
  	/*
  	 * 1 - parent dir inode
  	 * 2 - dir entries
  	 * 1 - root item
  	 * 2 - root ref/backref
  	 * 1 - root of snapshot
  	 * 1 - UUID item
  	 */
  	ret = btrfs_subvolume_reserve_metadata(BTRFS_I(dir)->root,
  					&pending_snapshot->block_rsv, 8,
  					&pending_snapshot->qgroup_reserved,
  					false);
  	if (ret)
  		goto dec_and_free;
  
  	pending_snapshot->dentry = dentry;
  	pending_snapshot->root = root;
  	pending_snapshot->readonly = readonly;
  	pending_snapshot->dir = dir;
  	pending_snapshot->inherit = inherit;
  
  	trans = btrfs_start_transaction(root, 0);
  	if (IS_ERR(trans)) {
  		ret = PTR_ERR(trans);
  		goto fail;
  	}
  
  	spin_lock(&fs_info->trans_lock);
  	list_add(&pending_snapshot->list,
  		 &trans->transaction->pending_snapshots);
  	spin_unlock(&fs_info->trans_lock);
  	if (async_transid) {
  		*async_transid = trans->transid;
  		ret = btrfs_commit_transaction_async(trans, 1);
  		if (ret)
  			ret = btrfs_commit_transaction(trans);
  	} else {
  		ret = btrfs_commit_transaction(trans);
  	}
  	if (ret)
  		goto fail;
  
  	ret = pending_snapshot->error;
  	if (ret)
  		goto fail;
  
  	ret = btrfs_orphan_cleanup(pending_snapshot->snap);
  	if (ret)
  		goto fail;
  
  	inode = btrfs_lookup_dentry(d_inode(dentry->d_parent), dentry);
  	if (IS_ERR(inode)) {
  		ret = PTR_ERR(inode);
  		goto fail;
  	}
  
  	d_instantiate(dentry, inode);
  	ret = 0;
  fail:
  	btrfs_subvolume_release_metadata(fs_info, &pending_snapshot->block_rsv);
  dec_and_free:
  	if (atomic_dec_and_test(&root->will_be_snapshotted))
  		wake_up_atomic_t(&root->will_be_snapshotted);
  free_pending:
  	kfree(pending_snapshot->root_item);
  	btrfs_free_path(pending_snapshot->path);
  	kfree(pending_snapshot);
  
  	return ret;
  }
  
  /*  copy of may_delete in fs/namei.c()
   *	Check whether we can remove a link victim from directory dir, check
   *  whether the type of victim is right.
   *  1. We can't do it if dir is read-only (done in permission())
   *  2. We should have write and exec permissions on dir
   *  3. We can't remove anything from append-only dir
   *  4. We can't do anything with immutable dir (done in permission())
   *  5. If the sticky bit on dir is set we should either
   *	a. be owner of dir, or
   *	b. be owner of victim, or
   *	c. have CAP_FOWNER capability
   *  6. If the victim is append-only or immutable we can't do anything with
   *     links pointing to it.
   *  7. If we were asked to remove a directory and victim isn't one - ENOTDIR.
   *  8. If we were asked to remove a non-directory and victim isn't one - EISDIR.
   *  9. We can't remove a root or mountpoint.
   * 10. We don't allow removal of NFS sillyrenamed files; it's handled by
   *     nfs_async_unlink().
   */
  
  static int btrfs_may_delete(struct inode *dir, struct dentry *victim, int isdir)
  {
  	int error;
  
  	if (d_really_is_negative(victim))
  		return -ENOENT;
  
  	BUG_ON(d_inode(victim->d_parent) != dir);
  	audit_inode_child(dir, victim, AUDIT_TYPE_CHILD_DELETE);
  
  	error = inode_permission(dir, MAY_WRITE | MAY_EXEC);
  	if (error)
  		return error;
  	if (IS_APPEND(dir))
  		return -EPERM;
  	if (check_sticky(dir, d_inode(victim)) || IS_APPEND(d_inode(victim)) ||
  	    IS_IMMUTABLE(d_inode(victim)) || IS_SWAPFILE(d_inode(victim)))
  		return -EPERM;
  	if (isdir) {
  		if (!d_is_dir(victim))
  			return -ENOTDIR;
  		if (IS_ROOT(victim))
  			return -EBUSY;
  	} else if (d_is_dir(victim))
  		return -EISDIR;
  	if (IS_DEADDIR(dir))
  		return -ENOENT;
  	if (victim->d_flags & DCACHE_NFSFS_RENAMED)
  		return -EBUSY;
  	return 0;
  }
  
  /* copy of may_create in fs/namei.c() */
  static inline int btrfs_may_create(struct inode *dir, struct dentry *child)
  {
  	if (d_really_is_positive(child))
  		return -EEXIST;
  	if (IS_DEADDIR(dir))
  		return -ENOENT;
  	return inode_permission(dir, MAY_WRITE | MAY_EXEC);
  }
  
  /*
   * Create a new subvolume below @parent.  This is largely modeled after
   * sys_mkdirat and vfs_mkdir, but we only do a single component lookup
   * inside this filesystem so it's quite a bit simpler.
   */
  static noinline int btrfs_mksubvol(const struct path *parent,
  				   const char *name, int namelen,
  				   struct btrfs_root *snap_src,
  				   u64 *async_transid, bool readonly,
  				   struct btrfs_qgroup_inherit *inherit)
  {
  	struct inode *dir = d_inode(parent->dentry);
  	struct btrfs_fs_info *fs_info = btrfs_sb(dir->i_sb);
  	struct dentry *dentry;
  	int error;
  
  	error = down_write_killable_nested(&dir->i_rwsem, I_MUTEX_PARENT);
  	if (error == -EINTR)
  		return error;
  
  	dentry = lookup_one_len(name, parent->dentry, namelen);
  	error = PTR_ERR(dentry);
  	if (IS_ERR(dentry))
  		goto out_unlock;
  
  	error = btrfs_may_create(dir, dentry);
  	if (error)
  		goto out_dput;
  
  	/*
  	 * even if this name doesn't exist, we may get hash collisions.
  	 * check for them now when we can safely fail
  	 */
  	error = btrfs_check_dir_item_collision(BTRFS_I(dir)->root,
  					       dir->i_ino, name,
  					       namelen);
  	if (error)
  		goto out_dput;
  
  	down_read(&fs_info->subvol_sem);
  
  	if (btrfs_root_refs(&BTRFS_I(dir)->root->root_item) == 0)
  		goto out_up_read;
  
  	if (snap_src) {
  		error = create_snapshot(snap_src, dir, dentry,
  					async_transid, readonly, inherit);
  	} else {
  		error = create_subvol(dir, dentry, name, namelen,
  				      async_transid, inherit);
  	}
  	if (!error)
  		fsnotify_mkdir(dir, dentry);
  out_up_read:
  	up_read(&fs_info->subvol_sem);
  out_dput:
  	dput(dentry);
  out_unlock:
  	inode_unlock(dir);
  	return error;
  }
  
  /*
   * When we're defragging a range, we don't want to kick it off again
   * if it is really just waiting for delalloc to send it down.
   * If we find a nice big extent or delalloc range for the bytes in the
   * file you want to defrag, we return 0 to let you know to skip this
   * part of the file
   */
  static int check_defrag_in_cache(struct inode *inode, u64 offset, u32 thresh)
  {
  	struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
  	struct extent_map *em = NULL;
  	struct extent_map_tree *em_tree = &BTRFS_I(inode)->extent_tree;
  	u64 end;
  
  	read_lock(&em_tree->lock);
  	em = lookup_extent_mapping(em_tree, offset, PAGE_SIZE);
  	read_unlock(&em_tree->lock);
  
  	if (em) {
  		end = extent_map_end(em);
  		free_extent_map(em);
  		if (end - offset > thresh)
  			return 0;
  	}
  	/* if we already have a nice delalloc here, just stop */
  	thresh /= 2;
  	end = count_range_bits(io_tree, &offset, offset + thresh,
  			       thresh, EXTENT_DELALLOC, 1);
  	if (end >= thresh)
  		return 0;
  	return 1;
  }
  
  /*
   * helper function to walk through a file and find extents
   * newer than a specific transid, and smaller than thresh.
   *
   * This is used by the defragging code to find new and small
   * extents
   */
  static int find_new_extents(struct btrfs_root *root,
  			    struct inode *inode, u64 newer_than,
  			    u64 *off, u32 thresh)
  {
  	struct btrfs_path *path;
  	struct btrfs_key min_key;
  	struct extent_buffer *leaf;
  	struct btrfs_file_extent_item *extent;
  	int type;
  	int ret;
  	u64 ino = btrfs_ino(BTRFS_I(inode));
  
  	path = btrfs_alloc_path();
  	if (!path)
  		return -ENOMEM;
  
  	min_key.objectid = ino;
  	min_key.type = BTRFS_EXTENT_DATA_KEY;
  	min_key.offset = *off;
  
  	while (1) {
  		ret = btrfs_search_forward(root, &min_key, path, newer_than);
  		if (ret != 0)
  			goto none;
  process_slot:
  		if (min_key.objectid != ino)
  			goto none;
  		if (min_key.type != BTRFS_EXTENT_DATA_KEY)
  			goto none;
  
  		leaf = path->nodes[0];
  		extent = btrfs_item_ptr(leaf, path->slots[0],
  					struct btrfs_file_extent_item);
  
  		type = btrfs_file_extent_type(leaf, extent);
  		if (type == BTRFS_FILE_EXTENT_REG &&
  		    btrfs_file_extent_num_bytes(leaf, extent) < thresh &&
  		    check_defrag_in_cache(inode, min_key.offset, thresh)) {
  			*off = min_key.offset;
  			btrfs_free_path(path);
  			return 0;
  		}
  
  		path->slots[0]++;
  		if (path->slots[0] < btrfs_header_nritems(leaf)) {
  			btrfs_item_key_to_cpu(leaf, &min_key, path->slots[0]);
  			goto process_slot;
  		}
  
  		if (min_key.offset == (u64)-1)
  			goto none;
  
  		min_key.offset++;
  		btrfs_release_path(path);
  	}
  none:
  	btrfs_free_path(path);
  	return -ENOENT;
  }
  
  static struct extent_map *defrag_lookup_extent(struct inode *inode, u64 start)
  {
  	struct extent_map_tree *em_tree = &BTRFS_I(inode)->extent_tree;
  	struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
  	struct extent_map *em;
  	u64 len = PAGE_SIZE;
  
  	/*
  	 * hopefully we have this extent in the tree already, try without
  	 * the full extent lock
  	 */
  	read_lock(&em_tree->lock);
  	em = lookup_extent_mapping(em_tree, start, len);
  	read_unlock(&em_tree->lock);
  
  	if (!em) {
  		struct extent_state *cached = NULL;
  		u64 end = start + len - 1;
  
  		/* get the big lock and read metadata off disk */
  		lock_extent_bits(io_tree, start, end, &cached);
  		em = btrfs_get_extent(BTRFS_I(inode), NULL, 0, start, len, 0);
  		unlock_extent_cached(io_tree, start, end, &cached, GFP_NOFS);
  
  		if (IS_ERR(em))
  			return NULL;
  	}
  
  	return em;
  }
  
  static bool defrag_check_next_extent(struct inode *inode, struct extent_map *em)
  {
  	struct extent_map *next;
  	bool ret = true;
  
  	/* this is the last extent */
  	if (em->start + em->len >= i_size_read(inode))
  		return false;
  
  	next = defrag_lookup_extent(inode, em->start + em->len);
  	if (!next || next->block_start >= EXTENT_MAP_LAST_BYTE)
  		ret = false;
  	else if ((em->block_start + em->block_len == next->block_start) &&
  		 (em->block_len > SZ_128K && next->block_len > SZ_128K))
  		ret = false;
  
  	free_extent_map(next);
  	return ret;
  }
  
  static int should_defrag_range(struct inode *inode, u64 start, u32 thresh,
  			       u64 *last_len, u64 *skip, u64 *defrag_end,
  			       int compress)
  {
  	struct extent_map *em;
  	int ret = 1;
  	bool next_mergeable = true;
  	bool prev_mergeable = true;
  
  	/*
  	 * make sure that once we start defragging an extent, we keep on
  	 * defragging it
  	 */
  	if (start < *defrag_end)
  		return 1;
  
  	*skip = 0;
  
  	em = defrag_lookup_extent(inode, start);
  	if (!em)
  		return 0;
  
  	/* this will cover holes, and inline extents */
  	if (em->block_start >= EXTENT_MAP_LAST_BYTE) {
  		ret = 0;
  		goto out;
  	}
  
  	if (!*defrag_end)
  		prev_mergeable = false;
  
  	next_mergeable = defrag_check_next_extent(inode, em);
  	/*
  	 * we hit a real extent, if it is big or the next extent is not a
  	 * real extent, don't bother defragging it
  	 */
  	if (!compress && (*last_len == 0 || *last_len >= thresh) &&
  	    (em->len >= thresh || (!next_mergeable && !prev_mergeable)))
  		ret = 0;
  out:
  	/*
  	 * last_len ends up being a counter of how many bytes we've defragged.
  	 * every time we choose not to defrag an extent, we reset *last_len
  	 * so that the next tiny extent will force a defrag.
  	 *
  	 * The end result of this is that tiny extents before a single big
  	 * extent will force at least part of that big extent to be defragged.
  	 */
  	if (ret) {
  		*defrag_end = extent_map_end(em);
  	} else {
  		*last_len = 0;
  		*skip = extent_map_end(em);
  		*defrag_end = 0;
  	}
  
  	free_extent_map(em);
  	return ret;
  }
  
  /*
   * it doesn't do much good to defrag one or two pages
   * at a time.  This pulls in a nice chunk of pages
   * to COW and defrag.
   *
   * It also makes sure the delalloc code has enough
   * dirty data to avoid making new small extents as part
   * of the defrag
   *
   * It's a good idea to start RA on this range
   * before calling this.
   */
  static int cluster_pages_for_defrag(struct inode *inode,
  				    struct page **pages,
  				    unsigned long start_index,
  				    unsigned long num_pages)
  {
  	unsigned long file_end;
  	u64 isize = i_size_read(inode);
  	u64 page_start;
  	u64 page_end;
  	u64 page_cnt;
  	int ret;
  	int i;
  	int i_done;
  	struct btrfs_ordered_extent *ordered;
  	struct extent_state *cached_state = NULL;
  	struct extent_io_tree *tree;
  	struct extent_changeset *data_reserved = NULL;
  	gfp_t mask = btrfs_alloc_write_mask(inode->i_mapping);
  
  	file_end = (isize - 1) >> PAGE_SHIFT;
  	if (!isize || start_index > file_end)
  		return 0;
  
  	page_cnt = min_t(u64, (u64)num_pages, (u64)file_end - start_index + 1);
  
  	ret = btrfs_delalloc_reserve_space(inode, &data_reserved,
  			start_index << PAGE_SHIFT,
  			page_cnt << PAGE_SHIFT);
  	if (ret)
  		return ret;
  	i_done = 0;
  	tree = &BTRFS_I(inode)->io_tree;
  
  	/* step one, lock all the pages */
  	for (i = 0; i < page_cnt; i++) {
  		struct page *page;
  again:
  		page = find_or_create_page(inode->i_mapping,
  					   start_index + i, mask);
  		if (!page)
  			break;
  
  		page_start = page_offset(page);
  		page_end = page_start + PAGE_SIZE - 1;
  		while (1) {
  			lock_extent_bits(tree, page_start, page_end,
  					 &cached_state);
  			ordered = btrfs_lookup_ordered_extent(inode,
  							      page_start);
  			unlock_extent_cached(tree, page_start, page_end,
  					     &cached_state, GFP_NOFS);
  			if (!ordered)
  				break;
  
  			unlock_page(page);
  			btrfs_start_ordered_extent(inode, ordered, 1);
  			btrfs_put_ordered_extent(ordered);
  			lock_page(page);
  			/*
  			 * we unlocked the page above, so we need check if
  			 * it was released or not.
  			 */
  			if (page->mapping != inode->i_mapping) {
  				unlock_page(page);
  				put_page(page);
  				goto again;
  			}
  		}
  
  		if (!PageUptodate(page)) {
  			btrfs_readpage(NULL, page);
  			lock_page(page);
  			if (!PageUptodate(page)) {
  				unlock_page(page);
  				put_page(page);
  				ret = -EIO;
  				break;
  			}
  		}
  
  		if (page->mapping != inode->i_mapping) {
  			unlock_page(page);
  			put_page(page);
  			goto again;
  		}
  
  		pages[i] = page;
  		i_done++;
  	}
  	if (!i_done || ret)
  		goto out;
  
  	if (!(inode->i_sb->s_flags & MS_ACTIVE))
  		goto out;
  
  	/*
  	 * so now we have a nice long stream of locked
  	 * and up to date pages, lets wait on them
  	 */
  	for (i = 0; i < i_done; i++)
  		wait_on_page_writeback(pages[i]);
  
  	page_start = page_offset(pages[0]);
  	page_end = page_offset(pages[i_done - 1]) + PAGE_SIZE;
  
  	lock_extent_bits(&BTRFS_I(inode)->io_tree,
  			 page_start, page_end - 1, &cached_state);
  	clear_extent_bit(&BTRFS_I(inode)->io_tree, page_start,
  			  page_end - 1, EXTENT_DIRTY | EXTENT_DELALLOC |
  			  EXTENT_DO_ACCOUNTING | EXTENT_DEFRAG, 0, 0,
  			  &cached_state, GFP_NOFS);
  
  	if (i_done != page_cnt) {
  		spin_lock(&BTRFS_I(inode)->lock);
  		BTRFS_I(inode)->outstanding_extents++;
  		spin_unlock(&BTRFS_I(inode)->lock);
  		btrfs_delalloc_release_space(inode, data_reserved,
  				start_index << PAGE_SHIFT,
  				(page_cnt - i_done) << PAGE_SHIFT);
  	}
  
  
  	set_extent_defrag(&BTRFS_I(inode)->io_tree, page_start, page_end - 1,
  			  &cached_state);
  
  	unlock_extent_cached(&BTRFS_I(inode)->io_tree,
  			     page_start, page_end - 1, &cached_state,
  			     GFP_NOFS);
  
  	for (i = 0; i < i_done; i++) {
  		clear_page_dirty_for_io(pages[i]);
  		ClearPageChecked(pages[i]);
  		set_page_extent_mapped(pages[i]);
  		set_page_dirty(pages[i]);
  		unlock_page(pages[i]);
  		put_page(pages[i]);
  	}
  	extent_changeset_free(data_reserved);
  	return i_done;
  out:
  	for (i = 0; i < i_done; i++) {
  		unlock_page(pages[i]);
  		put_page(pages[i]);
  	}
  	btrfs_delalloc_release_space(inode, data_reserved,
  			start_index << PAGE_SHIFT,
  			page_cnt << PAGE_SHIFT);
  	extent_changeset_free(data_reserved);
  	return ret;
  
  }
  
  int btrfs_defrag_file(struct inode *inode, struct file *file,
  		      struct btrfs_ioctl_defrag_range_args *range,
  		      u64 newer_than, unsigned long max_to_defrag)
  {
  	struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
  	struct btrfs_root *root = BTRFS_I(inode)->root;
  	struct file_ra_state *ra = NULL;
  	unsigned long last_index;
  	u64 isize = i_size_read(inode);
  	u64 last_len = 0;
  	u64 skip = 0;
  	u64 defrag_end = 0;
  	u64 newer_off = range->start;
  	unsigned long i;
  	unsigned long ra_index = 0;
  	int ret;
  	int defrag_count = 0;
  	int compress_type = BTRFS_COMPRESS_ZLIB;
  	u32 extent_thresh = range->extent_thresh;
  	unsigned long max_cluster = SZ_256K >> PAGE_SHIFT;
  	unsigned long cluster = max_cluster;
  	u64 new_align = ~((u64)SZ_128K - 1);
  	struct page **pages = NULL;
  	bool do_compress = range->flags & BTRFS_DEFRAG_RANGE_COMPRESS;
  
  	if (isize == 0)
  		return 0;
  
  	if (range->start >= isize)
  		return -EINVAL;
  
  	if (do_compress) {
  		if (range->compress_type > BTRFS_COMPRESS_TYPES)
  			return -EINVAL;
  		if (range->compress_type)
  			compress_type = range->compress_type;
  	}
  
  	if (extent_thresh == 0)
  		extent_thresh = SZ_256K;
  
  	/*
  	 * If we were not given a file, allocate a readahead context. As
  	 * readahead is just an optimization, defrag will work without it so
  	 * we don't error out.
  	 */
  	if (!file) {
  		ra = kzalloc(sizeof(*ra), GFP_KERNEL);
  		if (ra)
  			file_ra_state_init(ra, inode->i_mapping);
  	} else {
  		ra = &file->f_ra;
  	}
  
  	pages = kmalloc_array(max_cluster, sizeof(struct page *), GFP_KERNEL);
  	if (!pages) {
  		ret = -ENOMEM;
  		goto out_ra;
  	}
  
  	/* find the last page to defrag */
  	if (range->start + range->len > range->start) {
  		last_index = min_t(u64, isize - 1,
  			 range->start + range->len - 1) >> PAGE_SHIFT;
  	} else {
  		last_index = (isize - 1) >> PAGE_SHIFT;
  	}
  
  	if (newer_than) {
  		ret = find_new_extents(root, inode, newer_than,
  				       &newer_off, SZ_64K);
  		if (!ret) {
  			range->start = newer_off;
  			/*
  			 * we always align our defrag to help keep
  			 * the extents in the file evenly spaced
  			 */
  			i = (newer_off & new_align) >> PAGE_SHIFT;
  		} else
  			goto out_ra;
  	} else {
  		i = range->start >> PAGE_SHIFT;
  	}
  	if (!max_to_defrag)
  		max_to_defrag = last_index - i + 1;
  
  	/*
  	 * make writeback starts from i, so the defrag range can be
  	 * written sequentially.
  	 */
  	if (i < inode->i_mapping->writeback_index)
  		inode->i_mapping->writeback_index = i;
  
  	while (i <= last_index && defrag_count < max_to_defrag &&
  	       (i < DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE))) {
  		/*
  		 * make sure we stop running if someone unmounts
  		 * the FS
  		 */
  		if (!(inode->i_sb->s_flags & MS_ACTIVE))
  			break;
  
  		if (btrfs_defrag_cancelled(fs_info)) {
  			btrfs_debug(fs_info, "defrag_file cancelled");
  			ret = -EAGAIN;
  			break;
  		}
  
  		if (!should_defrag_range(inode, (u64)i << PAGE_SHIFT,
  					 extent_thresh, &last_len, &skip,
  					 &defrag_end, do_compress)){
  			unsigned long next;
  			/*
  			 * the should_defrag function tells us how much to skip
  			 * bump our counter by the suggested amount
  			 */
  			next = DIV_ROUND_UP(skip, PAGE_SIZE);
  			i = max(i + 1, next);
  			continue;
  		}
  
  		if (!newer_than) {
  			cluster = (PAGE_ALIGN(defrag_end) >>
  				   PAGE_SHIFT) - i;
  			cluster = min(cluster, max_cluster);
  		} else {
  			cluster = max_cluster;
  		}
  
  		if (i + cluster > ra_index) {
  			ra_index = max(i, ra_index);
  			if (ra)
  				page_cache_sync_readahead(inode->i_mapping, ra,
  						file, ra_index, cluster);
  			ra_index += cluster;
  		}
  
  		inode_lock(inode);
  		if (do_compress)
  			BTRFS_I(inode)->defrag_compress = compress_type;
  		ret = cluster_pages_for_defrag(inode, pages, i, cluster);
  		if (ret < 0) {
  			inode_unlock(inode);
  			goto out_ra;
  		}
  
  		defrag_count += ret;
  		balance_dirty_pages_ratelimited(inode->i_mapping);
  		inode_unlock(inode);
  
  		if (newer_than) {
  			if (newer_off == (u64)-1)
  				break;
  
  			if (ret > 0)
  				i += ret;
  
  			newer_off = max(newer_off + 1,
  					(u64)i << PAGE_SHIFT);
  
  			ret = find_new_extents(root, inode, newer_than,
  					       &newer_off, SZ_64K);
  			if (!ret) {
  				range->start = newer_off;
  				i = (newer_off & new_align) >> PAGE_SHIFT;
  			} else {
  				break;
  			}
  		} else {
  			if (ret > 0) {
  				i += ret;
  				last_len += ret << PAGE_SHIFT;
  			} else {
  				i++;
  				last_len = 0;
  			}
  		}
  	}
  
  	if ((range->flags & BTRFS_DEFRAG_RANGE_START_IO)) {
  		filemap_flush(inode->i_mapping);
  		if (test_bit(BTRFS_INODE_HAS_ASYNC_EXTENT,
  			     &BTRFS_I(inode)->runtime_flags))
  			filemap_flush(inode->i_mapping);
  	}
  
  	if (do_compress) {
  		/* the filemap_flush will queue IO into the worker threads, but
  		 * we have to make sure the IO is actually started and that
  		 * ordered extents get created before we return
  		 */
  		atomic_inc(&fs_info->async_submit_draining);
  		while (atomic_read(&fs_info->nr_async_submits) ||
  		       atomic_read(&fs_info->async_delalloc_pages)) {
  			wait_event(fs_info->async_submit_wait,
  				   (atomic_read(&fs_info->nr_async_submits) == 0 &&
  				    atomic_read(&fs_info->async_delalloc_pages) == 0));
  		}
  		atomic_dec(&fs_info->async_submit_draining);
  	}
  
  	if (range->compress_type == BTRFS_COMPRESS_LZO) {
  		btrfs_set_fs_incompat(fs_info, COMPRESS_LZO);
  	} else if (range->compress_type == BTRFS_COMPRESS_ZSTD) {
  		btrfs_set_fs_incompat(fs_info, COMPRESS_ZSTD);
  	}
  
  	ret = defrag_count;
  
  out_ra:
  	if (do_compress) {
  		inode_lock(inode);
  		BTRFS_I(inode)->defrag_compress = BTRFS_COMPRESS_NONE;
  		inode_unlock(inode);
  	}
  	if (!file)
  		kfree(ra);
  	kfree(pages);
  	return ret;
  }
  
  static noinline int btrfs_ioctl_resize(struct file *file,
  					void __user *arg)
  {
  	struct inode *inode = file_inode(file);
  	struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
  	u64 new_size;
  	u64 old_size;
  	u64 devid = 1;
  	struct btrfs_root *root = BTRFS_I(inode)->root;
  	struct btrfs_ioctl_vol_args *vol_args;
  	struct btrfs_trans_handle *trans;
  	struct btrfs_device *device = NULL;
  	char *sizestr;
  	char *retptr;
  	char *devstr = NULL;
  	int ret = 0;
  	int mod = 0;
  
  	if (!capable(CAP_SYS_ADMIN))
  		return -EPERM;
  
  	ret = mnt_want_write_file(file);
  	if (ret)
  		return ret;
  
  	if (test_and_set_bit(BTRFS_FS_EXCL_OP, &fs_info->flags)) {
  		mnt_drop_write_file(file);
  		return BTRFS_ERROR_DEV_EXCL_RUN_IN_PROGRESS;
  	}
  
  	mutex_lock(&fs_info->volume_mutex);
  	vol_args = memdup_user(arg, sizeof(*vol_args));
  	if (IS_ERR(vol_args)) {
  		ret = PTR_ERR(vol_args);
  		goto out;
  	}
  
  	vol_args->name[BTRFS_PATH_NAME_MAX] = '\0';
  
  	sizestr = vol_args->name;
  	devstr = strchr(sizestr, ':');
  	if (devstr) {
  		sizestr = devstr + 1;
  		*devstr = '\0';
  		devstr = vol_args->name;
  		ret = kstrtoull(devstr, 10, &devid);
  		if (ret)
  			goto out_free;
  		if (!devid) {
  			ret = -EINVAL;
  			goto out_free;
  		}
  		btrfs_info(fs_info, "resizing devid %llu", devid);
  	}
  
  	device = btrfs_find_device(fs_info, devid, NULL, NULL);
  	if (!device) {
  		btrfs_info(fs_info, "resizer unable to find device %llu",
  			   devid);
  		ret = -ENODEV;
  		goto out_free;
  	}
  
  	if (!device->writeable) {
  		btrfs_info(fs_info,
  			   "resizer unable to apply on readonly device %llu",
  		       devid);
  		ret = -EPERM;
  		goto out_free;
  	}
  
  	if (!strcmp(sizestr, "max"))
  		new_size = device->bdev->bd_inode->i_size;
  	else {
  		if (sizestr[0] == '-') {
  			mod = -1;
  			sizestr++;
  		} else if (sizestr[0] == '+') {
  			mod = 1;
  			sizestr++;
  		}
  		new_size = memparse(sizestr, &retptr);
  		if (*retptr != '\0' || new_size == 0) {
  			ret = -EINVAL;
  			goto out_free;
  		}
  	}
  
  	if (device->is_tgtdev_for_dev_replace) {
  		ret = -EPERM;
  		goto out_free;
  	}
  
  	old_size = btrfs_device_get_total_bytes(device);
  
  	if (mod < 0) {
  		if (new_size > old_size) {
  			ret = -EINVAL;
  			goto out_free;
  		}
  		new_size = old_size - new_size;
  	} else if (mod > 0) {
  		if (new_size > ULLONG_MAX - old_size) {
  			ret = -ERANGE;
  			goto out_free;
  		}
  		new_size = old_size + new_size;
  	}
  
  	if (new_size < SZ_256M) {
  		ret = -EINVAL;
  		goto out_free;
  	}
  	if (new_size > device->bdev->bd_inode->i_size) {
  		ret = -EFBIG;
  		goto out_free;
  	}
  
  	new_size = round_down(new_size, fs_info->sectorsize);
  
  	btrfs_info_in_rcu(fs_info, "new size for %s is %llu",
  			  rcu_str_deref(device->name), new_size);
  
  	if (new_size > old_size) {
  		trans = btrfs_start_transaction(root, 0);
  		if (IS_ERR(trans)) {
  			ret = PTR_ERR(trans);
  			goto out_free;
  		}
  		ret = btrfs_grow_device(trans, device, new_size);
  		btrfs_commit_transaction(trans);
  	} else if (new_size < old_size) {
  		ret = btrfs_shrink_device(device, new_size);
  	} /* equal, nothing need to do */
  
  out_free:
  	kfree(vol_args);
  out:
  	mutex_unlock(&fs_info->volume_mutex);
  	clear_bit(BTRFS_FS_EXCL_OP, &fs_info->flags);
  	mnt_drop_write_file(file);
  	return ret;
  }
  
  static noinline int btrfs_ioctl_snap_create_transid(struct file *file,
  				const char *name, unsigned long fd, int subvol,
  				u64 *transid, bool readonly,
  				struct btrfs_qgroup_inherit *inherit)
  {
  	int namelen;
  	int ret = 0;
  
  	if (!S_ISDIR(file_inode(file)->i_mode))
  		return -ENOTDIR;
  
  	ret = mnt_want_write_file(file);
  	if (ret)
  		goto out;
  
  	namelen = strlen(name);
  	if (strchr(name, '/')) {
  		ret = -EINVAL;
  		goto out_drop_write;
  	}
  
  	if (name[0] == '.' &&
  	   (namelen == 1 || (name[1] == '.' && namelen == 2))) {
  		ret = -EEXIST;
  		goto out_drop_write;
  	}
  
  	if (subvol) {
  		ret = btrfs_mksubvol(&file->f_path, name, namelen,
  				     NULL, transid, readonly, inherit);
  	} else {
  		struct fd src = fdget(fd);
  		struct inode *src_inode;
  		if (!src.file) {
  			ret = -EINVAL;
  			goto out_drop_write;
  		}
  
  		src_inode = file_inode(src.file);
  		if (src_inode->i_sb != file_inode(file)->i_sb) {
  			btrfs_info(BTRFS_I(file_inode(file))->root->fs_info,
  				   "Snapshot src from another FS");
  			ret = -EXDEV;
  		} else if (!inode_owner_or_capable(src_inode)) {
  			/*
  			 * Subvolume creation is not restricted, but snapshots
  			 * are limited to own subvolumes only
  			 */
  			ret = -EPERM;
  		} else {
  			ret = btrfs_mksubvol(&file->f_path, name, namelen,
  					     BTRFS_I(src_inode)->root,
  					     transid, readonly, inherit);
  		}
  		fdput(src);
  	}
  out_drop_write:
  	mnt_drop_write_file(file);
  out:
  	return ret;
  }
  
  static noinline int btrfs_ioctl_snap_create(struct file *file,
  					    void __user *arg, int subvol)
  {
  	struct btrfs_ioctl_vol_args *vol_args;
  	int ret;
  
  	if (!S_ISDIR(file_inode(file)->i_mode))
  		return -ENOTDIR;
  
  	vol_args = memdup_user(arg, sizeof(*vol_args));
  	if (IS_ERR(vol_args))
  		return PTR_ERR(vol_args);
  	vol_args->name[BTRFS_PATH_NAME_MAX] = '\0';
  
  	ret = btrfs_ioctl_snap_create_transid(file, vol_args->name,
  					      vol_args->fd, subvol,
  					      NULL, false, NULL);
  
  	kfree(vol_args);
  	return ret;
  }
  
  static noinline int btrfs_ioctl_snap_create_v2(struct file *file,
  					       void __user *arg, int subvol)
  {
  	struct btrfs_ioctl_vol_args_v2 *vol_args;
  	int ret;
  	u64 transid = 0;
  	u64 *ptr = NULL;
  	bool readonly = false;
  	struct btrfs_qgroup_inherit *inherit = NULL;
  
  	if (!S_ISDIR(file_inode(file)->i_mode))
  		return -ENOTDIR;
  
  	vol_args = memdup_user(arg, sizeof(*vol_args));
  	if (IS_ERR(vol_args))
  		return PTR_ERR(vol_args);
  	vol_args->name[BTRFS_SUBVOL_NAME_MAX] = '\0';
  
  	if (vol_args->flags &
  	    ~(BTRFS_SUBVOL_CREATE_ASYNC | BTRFS_SUBVOL_RDONLY |
  	      BTRFS_SUBVOL_QGROUP_INHERIT)) {
  		ret = -EOPNOTSUPP;
  		goto free_args;
  	}
  
  	if (vol_args->flags & BTRFS_SUBVOL_CREATE_ASYNC)
  		ptr = &transid;
  	if (vol_args->flags & BTRFS_SUBVOL_RDONLY)
  		readonly = true;
  	if (vol_args->flags & BTRFS_SUBVOL_QGROUP_INHERIT) {
  		if (vol_args->size > PAGE_SIZE) {
  			ret = -EINVAL;
  			goto free_args;
  		}
  		inherit = memdup_user(vol_args->qgroup_inherit, vol_args->size);
  		if (IS_ERR(inherit)) {
  			ret = PTR_ERR(inherit);
  			goto free_args;
  		}
  	}
  
  	ret = btrfs_ioctl_snap_create_transid(file, vol_args->name,
  					      vol_args->fd, subvol, ptr,
  					      readonly, inherit);
  	if (ret)
  		goto free_inherit;
  
  	if (ptr && copy_to_user(arg +
  				offsetof(struct btrfs_ioctl_vol_args_v2,
  					transid),
  				ptr, sizeof(*ptr)))
  		ret = -EFAULT;
  
  free_inherit:
  	kfree(inherit);
  free_args:
  	kfree(vol_args);
  	return ret;
  }
  
  static noinline int btrfs_ioctl_subvol_getflags(struct file *file,
  						void __user *arg)
  {
  	struct inode *inode = file_inode(file);
  	struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
  	struct btrfs_root *root = BTRFS_I(inode)->root;
  	int ret = 0;
  	u64 flags = 0;
  
  	if (btrfs_ino(BTRFS_I(inode)) != BTRFS_FIRST_FREE_OBJECTID)
  		return -EINVAL;
  
  	down_read(&fs_info->subvol_sem);
  	if (btrfs_root_readonly(root))
  		flags |= BTRFS_SUBVOL_RDONLY;
  	up_read(&fs_info->subvol_sem);
  
  	if (copy_to_user(arg, &flags, sizeof(flags)))
  		ret = -EFAULT;
  
  	return ret;
  }
  
  static noinline int btrfs_ioctl_subvol_setflags(struct file *file,
  					      void __user *arg)
  {
  	struct inode *inode = file_inode(file);
  	struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
  	struct btrfs_root *root = BTRFS_I(inode)->root;
  	struct btrfs_trans_handle *trans;
  	u64 root_flags;
  	u64 flags;
  	int ret = 0;
  
  	if (!inode_owner_or_capable(inode))
  		return -EPERM;
  
  	ret = mnt_want_write_file(file);
  	if (ret)
  		goto out;
  
  	if (btrfs_ino(BTRFS_I(inode)) != BTRFS_FIRST_FREE_OBJECTID) {
  		ret = -EINVAL;
  		goto out_drop_write;
  	}
  
  	if (copy_from_user(&flags, arg, sizeof(flags))) {
  		ret = -EFAULT;
  		goto out_drop_write;
  	}
  
  	if (flags & BTRFS_SUBVOL_CREATE_ASYNC) {
  		ret = -EINVAL;
  		goto out_drop_write;
  	}
  
  	if (flags & ~BTRFS_SUBVOL_RDONLY) {
  		ret = -EOPNOTSUPP;
  		goto out_drop_write;
  	}
  
  	down_write(&fs_info->subvol_sem);
  
  	/* nothing to do */
  	if (!!(flags & BTRFS_SUBVOL_RDONLY) == btrfs_root_readonly(root))
  		goto out_drop_sem;
  
  	root_flags = btrfs_root_flags(&root->root_item);
  	if (flags & BTRFS_SUBVOL_RDONLY) {
  		btrfs_set_root_flags(&root->root_item,
  				     root_flags | BTRFS_ROOT_SUBVOL_RDONLY);
  	} else {
  		/*
  		 * Block RO -> RW transition if this subvolume is involved in
  		 * send
  		 */
  		spin_lock(&root->root_item_lock);
  		if (root->send_in_progress == 0) {
  			btrfs_set_root_flags(&root->root_item,
  				     root_flags & ~BTRFS_ROOT_SUBVOL_RDONLY);
  			spin_unlock(&root->root_item_lock);
  		} else {
  			spin_unlock(&root->root_item_lock);
  			btrfs_warn(fs_info,
  				   "Attempt to set subvolume %llu read-write during send",
  				   root->root_key.objectid);
  			ret = -EPERM;
  			goto out_drop_sem;
  		}
  	}
  
  	trans = btrfs_start_transaction(root, 1);
  	if (IS_ERR(trans)) {
  		ret = PTR_ERR(trans);
  		goto out_reset;
  	}
  
  	ret = btrfs_update_root(trans, fs_info->tree_root,
  				&root->root_key, &root->root_item);
  	if (ret < 0) {
  		btrfs_end_transaction(trans);
  		goto out_reset;
  	}
  
  	ret = btrfs_commit_transaction(trans);
  
  out_reset:
  	if (ret)
  		btrfs_set_root_flags(&root->root_item, root_flags);
  out_drop_sem:
  	up_write(&fs_info->subvol_sem);
  out_drop_write:
  	mnt_drop_write_file(file);
  out:
  	return ret;
  }
  
  /*
   * helper to check if the subvolume references other subvolumes
   */
  static noinline int may_destroy_subvol(struct btrfs_root *root)
  {
  	struct btrfs_fs_info *fs_info = root->fs_info;
  	struct btrfs_path *path;
  	struct btrfs_dir_item *di;
  	struct btrfs_key key;
  	u64 dir_id;
  	int ret;
  
  	path = btrfs_alloc_path();
  	if (!path)
  		return -ENOMEM;
  
  	/* Make sure this root isn't set as the default subvol */
  	dir_id = btrfs_super_root_dir(fs_info->super_copy);
  	di = btrfs_lookup_dir_item(NULL, fs_info->tree_root, path,
  				   dir_id, "default", 7, 0);
  	if (di && !IS_ERR(di)) {
  		btrfs_dir_item_key_to_cpu(path->nodes[0], di, &key);
  		if (key.objectid == root->root_key.objectid) {
  			ret = -EPERM;
  			btrfs_err(fs_info,
  				  "deleting default subvolume %llu is not allowed",
  				  key.objectid);
  			goto out;
  		}
  		btrfs_release_path(path);
  	}
  
  	key.objectid = root->root_key.objectid;
  	key.type = BTRFS_ROOT_REF_KEY;
  	key.offset = (u64)-1;
  
  	ret = btrfs_search_slot(NULL, fs_info->tree_root, &key, path, 0, 0);
  	if (ret < 0)
  		goto out;
  	BUG_ON(ret == 0);
  
  	ret = 0;
  	if (path->slots[0] > 0) {
  		path->slots[0]--;
  		btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
  		if (key.objectid == root->root_key.objectid &&
  		    key.type == BTRFS_ROOT_REF_KEY)
  			ret = -ENOTEMPTY;
  	}
  out:
  	btrfs_free_path(path);
  	return ret;
  }
  
  static noinline int key_in_sk(struct btrfs_key *key,
  			      struct btrfs_ioctl_search_key *sk)
  {
  	struct btrfs_key test;
  	int ret;
  
  	test.objectid = sk->min_objectid;
  	test.type = sk->min_type;
  	test.offset = sk->min_offset;
  
  	ret = btrfs_comp_cpu_keys(key, &test);
  	if (ret < 0)
  		return 0;
  
  	test.objectid = sk->max_objectid;
  	test.type = sk->max_type;
  	test.offset = sk->max_offset;
  
  	ret = btrfs_comp_cpu_keys(key, &test);
  	if (ret > 0)
  		return 0;
  	return 1;
  }
  
  static noinline int copy_to_sk(struct btrfs_path *path,
  			       struct btrfs_key *key,
  			       struct btrfs_ioctl_search_key *sk,
  			       size_t *buf_size,
  			       char __user *ubuf,
  			       unsigned long *sk_offset,
  			       int *num_found)
  {
  	u64 found_transid;
  	struct extent_buffer *leaf;
  	struct btrfs_ioctl_search_header sh;
  	struct btrfs_key test;
  	unsigned long item_off;
  	unsigned long item_len;
  	int nritems;
  	int i;
  	int slot;
  	int ret = 0;
  
  	leaf = path->nodes[0];
  	slot = path->slots[0];
  	nritems = btrfs_header_nritems(leaf);
  
  	if (btrfs_header_generation(leaf) > sk->max_transid) {
  		i = nritems;
  		goto advance_key;
  	}
  	found_transid = btrfs_header_generation(leaf);
  
  	for (i = slot; i < nritems; i++) {
  		item_off = btrfs_item_ptr_offset(leaf, i);
  		item_len = btrfs_item_size_nr(leaf, i);
  
  		btrfs_item_key_to_cpu(leaf, key, i);
  		if (!key_in_sk(key, sk))
  			continue;
  
  		if (sizeof(sh) + item_len > *buf_size) {
  			if (*num_found) {
  				ret = 1;
  				goto out;
  			}
  
  			/*
  			 * return one empty item back for v1, which does not
  			 * handle -EOVERFLOW
  			 */
  
  			*buf_size = sizeof(sh) + item_len;
  			item_len = 0;
  			ret = -EOVERFLOW;
  		}
  
  		if (sizeof(sh) + item_len + *sk_offset > *buf_size) {
  			ret = 1;
  			goto out;
  		}
  
  		sh.objectid = key->objectid;
  		sh.offset = key->offset;
  		sh.type = key->type;
  		sh.len = item_len;
  		sh.transid = found_transid;
  
  		/* copy search result header */
  		if (copy_to_user(ubuf + *sk_offset, &sh, sizeof(sh))) {
  			ret = -EFAULT;
  			goto out;
  		}
  
  		*sk_offset += sizeof(sh);
  
  		if (item_len) {
  			char __user *up = ubuf + *sk_offset;
  			/* copy the item */
  			if (read_extent_buffer_to_user(leaf, up,
  						       item_off, item_len)) {
  				ret = -EFAULT;
  				goto out;
  			}
  
  			*sk_offset += item_len;
  		}
  		(*num_found)++;
  
  		if (ret) /* -EOVERFLOW from above */
  			goto out;
  
  		if (*num_found >= sk->nr_items) {
  			ret = 1;
  			goto out;
  		}
  	}
  advance_key:
  	ret = 0;
  	test.objectid = sk->max_objectid;
  	test.type = sk->max_type;
  	test.offset = sk->max_offset;
  	if (btrfs_comp_cpu_keys(key, &test) >= 0)
  		ret = 1;
  	else if (key->offset < (u64)-1)
  		key->offset++;
  	else if (key->type < (u8)-1) {
  		key->offset = 0;
  		key->type++;
  	} else if (key->objectid < (u64)-1) {
  		key->offset = 0;
  		key->type = 0;
  		key->objectid++;
  	} else
  		ret = 1;
  out:
  	/*
  	 *  0: all items from this leaf copied, continue with next
  	 *  1: * more items can be copied, but unused buffer is too small
  	 *     * all items were found
  	 *     Either way, it will stops the loop which iterates to the next
  	 *     leaf
  	 *  -EOVERFLOW: item was to large for buffer
  	 *  -EFAULT: could not copy extent buffer back to userspace
  	 */
  	return ret;
  }
  
  static noinline int search_ioctl(struct inode *inode,
  				 struct btrfs_ioctl_search_key *sk,
  				 size_t *buf_size,
  				 char __user *ubuf)
  {
  	struct btrfs_fs_info *info = btrfs_sb(inode->i_sb);
  	struct btrfs_root *root;
  	struct btrfs_key key;
  	struct btrfs_path *path;
  	int ret;
  	int num_found = 0;
  	unsigned long sk_offset = 0;
  
  	if (*buf_size < sizeof(struct btrfs_ioctl_search_header)) {
  		*buf_size = sizeof(struct btrfs_ioctl_search_header);
  		return -EOVERFLOW;
  	}
  
  	path = btrfs_alloc_path();
  	if (!path)
  		return -ENOMEM;
  
  	if (sk->tree_id == 0) {
  		/* search the root of the inode that was passed */
  		root = BTRFS_I(inode)->root;
  	} else {
  		key.objectid = sk->tree_id;
  		key.type = BTRFS_ROOT_ITEM_KEY;
  		key.offset = (u64)-1;
  		root = btrfs_read_fs_root_no_name(info, &key);
  		if (IS_ERR(root)) {
  			btrfs_free_path(path);
  			return -ENOENT;
  		}
  	}
  
  	key.objectid = sk->min_objectid;
  	key.type = sk->min_type;
  	key.offset = sk->min_offset;
  
  	while (1) {
  		ret = btrfs_search_forward(root, &key, path, sk->min_transid);
  		if (ret != 0) {
  			if (ret > 0)
  				ret = 0;
  			goto err;
  		}
  		ret = copy_to_sk(path, &key, sk, buf_size, ubuf,
  				 &sk_offset, &num_found);
  		btrfs_release_path(path);
  		if (ret)
  			break;
  
  	}
  	if (ret > 0)
  		ret = 0;
  err:
  	sk->nr_items = num_found;
  	btrfs_free_path(path);
  	return ret;
  }
  
  static noinline int btrfs_ioctl_tree_search(struct file *file,
  					   void __user *argp)
  {
  	struct btrfs_ioctl_search_args __user *uargs;
  	struct btrfs_ioctl_search_key sk;
  	struct inode *inode;
  	int ret;
  	size_t buf_size;
  
  	if (!capable(CAP_SYS_ADMIN))
  		return -EPERM;
  
  	uargs = (struct btrfs_ioctl_search_args __user *)argp;
  
  	if (copy_from_user(&sk, &uargs->key, sizeof(sk)))
  		return -EFAULT;
  
  	buf_size = sizeof(uargs->buf);
  
  	inode = file_inode(file);
  	ret = search_ioctl(inode, &sk, &buf_size, uargs->buf);
  
  	/*
  	 * In the origin implementation an overflow is handled by returning a
  	 * search header with a len of zero, so reset ret.
  	 */
  	if (ret == -EOVERFLOW)
  		ret = 0;
  
  	if (ret == 0 && copy_to_user(&uargs->key, &sk, sizeof(sk)))
  		ret = -EFAULT;
  	return ret;
  }
  
  static noinline int btrfs_ioctl_tree_search_v2(struct file *file,
  					       void __user *argp)
  {
  	struct btrfs_ioctl_search_args_v2 __user *uarg;
  	struct btrfs_ioctl_search_args_v2 args;
  	struct inode *inode;
  	int ret;
  	size_t buf_size;
  	const size_t buf_limit = SZ_16M;
  
  	if (!capable(CAP_SYS_ADMIN))
  		return -EPERM;
  
  	/* copy search header and buffer size */
  	uarg = (struct btrfs_ioctl_search_args_v2 __user *)argp;
  	if (copy_from_user(&args, uarg, sizeof(args)))
  		return -EFAULT;
  
  	buf_size = args.buf_size;
  
  	/* limit result size to 16MB */
  	if (buf_size > buf_limit)
  		buf_size = buf_limit;
  
  	inode = file_inode(file);
  	ret = search_ioctl(inode, &args.key, &buf_size,
  			   (char *)(&uarg->buf[0]));
  	if (ret == 0 && copy_to_user(&uarg->key, &args.key, sizeof(args.key)))
  		ret = -EFAULT;
  	else if (ret == -EOVERFLOW &&
  		copy_to_user(&uarg->buf_size, &buf_size, sizeof(buf_size)))
  		ret = -EFAULT;
  
  	return ret;
  }
  
  /*
   * Search INODE_REFs to identify path name of 'dirid' directory
   * in a 'tree_id' tree. and sets path name to 'name'.
   */
  static noinline int btrfs_search_path_in_tree(struct btrfs_fs_info *info,
  				u64 tree_id, u64 dirid, char *name)
  {
  	struct btrfs_root *root;
  	struct btrfs_key key;
  	char *ptr;
  	int ret = -1;
  	int slot;
  	int len;
  	int total_len = 0;
  	struct btrfs_inode_ref *iref;
  	struct extent_buffer *l;
  	struct btrfs_path *path;
  
  	if (dirid == BTRFS_FIRST_FREE_OBJECTID) {
  		name[0]='\0';
  		return 0;
  	}
  
  	path = btrfs_alloc_path();
  	if (!path)
  		return -ENOMEM;
  
  	ptr = &name[BTRFS_INO_LOOKUP_PATH_MAX - 1];
  
  	key.objectid = tree_id;
  	key.type = BTRFS_ROOT_ITEM_KEY;
  	key.offset = (u64)-1;
  	root = btrfs_read_fs_root_no_name(info, &key);
  	if (IS_ERR(root)) {
  		btrfs_err(info, "could not find root %llu", tree_id);
  		ret = -ENOENT;
  		goto out;
  	}
  
  	key.objectid = dirid;
  	key.type = BTRFS_INODE_REF_KEY;
  	key.offset = (u64)-1;
  
  	while (1) {
  		ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
  		if (ret < 0)
  			goto out;
  		else if (ret > 0) {
  			ret = btrfs_previous_item(root, path, dirid,
  						  BTRFS_INODE_REF_KEY);
  			if (ret < 0)
  				goto out;
  			else if (ret > 0) {
  				ret = -ENOENT;
  				goto out;
  			}
  		}
  
  		l = path->nodes[0];
  		slot = path->slots[0];
  		btrfs_item_key_to_cpu(l, &key, slot);
  
  		iref = btrfs_item_ptr(l, slot, struct btrfs_inode_ref);
  		len = btrfs_inode_ref_name_len(l, iref);
  		ptr -= len + 1;
  		total_len += len + 1;
  		if (ptr < name) {
  			ret = -ENAMETOOLONG;
  			goto out;
  		}
  
  		*(ptr + len) = '/';
  		read_extent_buffer(l, ptr, (unsigned long)(iref + 1), len);
  
  		if (key.offset == BTRFS_FIRST_FREE_OBJECTID)
  			break;
  
  		btrfs_release_path(path);
  		key.objectid = key.offset;
  		key.offset = (u64)-1;
  		dirid = key.objectid;
  	}
  	memmove(name, ptr, total_len);
  	name[total_len] = '\0';
  	ret = 0;
  out:
  	btrfs_free_path(path);
  	return ret;
  }
  
  static noinline int btrfs_ioctl_ino_lookup(struct file *file,
  					   void __user *argp)
  {
  	 struct btrfs_ioctl_ino_lookup_args *args;
  	 struct inode *inode;
  	int ret = 0;
  
  	args = memdup_user(argp, sizeof(*args));
  	if (IS_ERR(args))
  		return PTR_ERR(args);
  
  	inode = file_inode(file);
  
  	/*
  	 * Unprivileged query to obtain the containing subvolume root id. The
  	 * path is reset so it's consistent with btrfs_search_path_in_tree.
  	 */
  	if (args->treeid == 0)
  		args->treeid = BTRFS_I(inode)->root->root_key.objectid;
  
  	if (args->objectid == BTRFS_FIRST_FREE_OBJECTID) {
  		args->name[0] = 0;
  		goto out;
  	}
  
  	if (!capable(CAP_SYS_ADMIN)) {
  		ret = -EPERM;
  		goto out;
  	}
  
  	ret = btrfs_search_path_in_tree(BTRFS_I(inode)->root->fs_info,
  					args->treeid, args->objectid,
  					args->name);
  
  out:
  	if (ret == 0 && copy_to_user(argp, args, sizeof(*args)))
  		ret = -EFAULT;
  
  	kfree(args);
  	return ret;
  }
  
  static noinline int btrfs_ioctl_snap_destroy(struct file *file,
  					     void __user *arg)
  {
  	struct dentry *parent = file->f_path.dentry;
  	struct btrfs_fs_info *fs_info = btrfs_sb(parent->d_sb);
  	struct dentry *dentry;
  	struct inode *dir = d_inode(parent);
  	struct inode *inode;
  	struct btrfs_root *root = BTRFS_I(dir)->root;
  	struct btrfs_root *dest = NULL;
  	struct btrfs_ioctl_vol_args *vol_args;
  	struct btrfs_trans_handle *trans;
  	struct btrfs_block_rsv block_rsv;
  	u64 root_flags;
  	u64 qgroup_reserved;
  	int namelen;
  	int ret;
  	int err = 0;
  
  	if (!S_ISDIR(dir->i_mode))
  		return -ENOTDIR;
  
  	vol_args = memdup_user(arg, sizeof(*vol_args));
  	if (IS_ERR(vol_args))
  		return PTR_ERR(vol_args);
  
  	vol_args->name[BTRFS_PATH_NAME_MAX] = '\0';
  	namelen = strlen(vol_args->name);
  	if (strchr(vol_args->name, '/') ||
  	    strncmp(vol_args->name, "..", namelen) == 0) {
  		err = -EINVAL;
  		goto out;
  	}
  
  	err = mnt_want_write_file(file);
  	if (err)
  		goto out;
  
  
  	err = down_write_killable_nested(&dir->i_rwsem, I_MUTEX_PARENT);
  	if (err == -EINTR)
  		goto out_drop_write;
  	dentry = lookup_one_len(vol_args->name, parent, namelen);
  	if (IS_ERR(dentry)) {
  		err = PTR_ERR(dentry);
  		goto out_unlock_dir;
  	}
  
  	if (d_really_is_negative(dentry)) {
  		err = -ENOENT;
  		goto out_dput;
  	}
  
  	inode = d_inode(dentry);
  	dest = BTRFS_I(inode)->root;
  	if (!capable(CAP_SYS_ADMIN)) {
  		/*
  		 * Regular user.  Only allow this with a special mount
  		 * option, when the user has write+exec access to the
  		 * subvol root, and when rmdir(2) would have been
  		 * allowed.
  		 *
  		 * Note that this is _not_ check that the subvol is
  		 * empty or doesn't contain data that we wouldn't
  		 * otherwise be able to delete.
  		 *
  		 * Users who want to delete empty subvols should try
  		 * rmdir(2).
  		 */
  		err = -EPERM;
  		if (!btrfs_test_opt(fs_info, USER_SUBVOL_RM_ALLOWED))
  			goto out_dput;
  
  		/*
  		 * Do not allow deletion if the parent dir is the same
  		 * as the dir to be deleted.  That means the ioctl
  		 * must be called on the dentry referencing the root
  		 * of the subvol, not a random directory contained
  		 * within it.
  		 */
  		err = -EINVAL;
  		if (root == dest)
  			goto out_dput;
  
  		err = inode_permission(inode, MAY_WRITE | MAY_EXEC);
  		if (err)
  			goto out_dput;
  	}
  
  	/* check if subvolume may be deleted by a user */
  	err = btrfs_may_delete(dir, dentry, 1);
  	if (err)
  		goto out_dput;
  
  	if (btrfs_ino(BTRFS_I(inode)) != BTRFS_FIRST_FREE_OBJECTID) {
  		err = -EINVAL;
  		goto out_dput;
  	}
  
  	inode_lock(inode);
  
  	/*
  	 * Don't allow to delete a subvolume with send in progress. This is
  	 * inside the i_mutex so the error handling that has to drop the bit
  	 * again is not run concurrently.
  	 */
  	spin_lock(&dest->root_item_lock);
  	root_flags = btrfs_root_flags(&dest->root_item);
  	if (dest->send_in_progress == 0) {
  		btrfs_set_root_flags(&dest->root_item,
  				root_flags | BTRFS_ROOT_SUBVOL_DEAD);
  		spin_unlock(&dest->root_item_lock);
  	} else {
  		spin_unlock(&dest->root_item_lock);
  		btrfs_warn(fs_info,
  			   "Attempt to delete subvolume %llu during send",
  			   dest->root_key.objectid);
  		err = -EPERM;
  		goto out_unlock_inode;
  	}
  
  	down_write(&fs_info->subvol_sem);
  
  	err = may_destroy_subvol(dest);
  	if (err)
  		goto out_up_write;
  
  	btrfs_init_block_rsv(&block_rsv, BTRFS_BLOCK_RSV_TEMP);
  	/*
  	 * One for dir inode, two for dir entries, two for root
  	 * ref/backref.
  	 */
  	err = btrfs_subvolume_reserve_metadata(root, &block_rsv,
  					       5, &qgroup_reserved, true);
  	if (err)
  		goto out_up_write;
  
  	trans = btrfs_start_transaction(root, 0);
  	if (IS_ERR(trans)) {
  		err = PTR_ERR(trans);
  		goto out_release;
  	}
  	trans->block_rsv = &block_rsv;
  	trans->bytes_reserved = block_rsv.size;
  
  	btrfs_record_snapshot_destroy(trans, BTRFS_I(dir));
  
  	ret = btrfs_unlink_subvol(trans, root, dir,
  				dest->root_key.objectid,
  				dentry->d_name.name,
  				dentry->d_name.len);
  	if (ret) {
  		err = ret;
  		btrfs_abort_transaction(trans, ret);
  		goto out_end_trans;
  	}
  
  	btrfs_record_root_in_trans(trans, dest);
  
  	memset(&dest->root_item.drop_progress, 0,
  		sizeof(dest->root_item.drop_progress));
  	dest->root_item.drop_level = 0;
  	btrfs_set_root_refs(&dest->root_item, 0);
  
  	if (!test_and_set_bit(BTRFS_ROOT_ORPHAN_ITEM_INSERTED, &dest->state)) {
  		ret = btrfs_insert_orphan_item(trans,
  					fs_info->tree_root,
  					dest->root_key.objectid);
  		if (ret) {
  			btrfs_abort_transaction(trans, ret);
  			err = ret;
  			goto out_end_trans;
  		}
  	}
  
  	ret = btrfs_uuid_tree_rem(trans, fs_info, dest->root_item.uuid,
  				  BTRFS_UUID_KEY_SUBVOL,
  				  dest->root_key.objectid);
  	if (ret && ret != -ENOENT) {
  		btrfs_abort_transaction(trans, ret);
  		err = ret;
  		goto out_end_trans;
  	}
  	if (!btrfs_is_empty_uuid(dest->root_item.received_uuid)) {
  		ret = btrfs_uuid_tree_rem(trans, fs_info,
  					  dest->root_item.received_uuid,
  					  BTRFS_UUID_KEY_RECEIVED_SUBVOL,
  					  dest->root_key.objectid);
  		if (ret && ret != -ENOENT) {
  			btrfs_abort_transaction(trans, ret);
  			err = ret;
  			goto out_end_trans;
  		}
  	}
  
  out_end_trans:
  	trans->block_rsv = NULL;
  	trans->bytes_reserved = 0;
  	ret = btrfs_end_transaction(trans);
  	if (ret && !err)
  		err = ret;
  	inode->i_flags |= S_DEAD;
  out_release:
  	btrfs_subvolume_release_metadata(fs_info, &block_rsv);
  out_up_write:
  	up_write(&fs_info->subvol_sem);
  	if (err) {
  		spin_lock(&dest->root_item_lock);
  		root_flags = btrfs_root_flags(&dest->root_item);
  		btrfs_set_root_flags(&dest->root_item,
  				root_flags & ~BTRFS_ROOT_SUBVOL_DEAD);
  		spin_unlock(&dest->root_item_lock);
  	}
  out_unlock_inode:
  	inode_unlock(inode);
  	if (!err) {
  		d_invalidate(dentry);
  		btrfs_invalidate_inodes(dest);
  		d_delete(dentry);
  		ASSERT(dest->send_in_progress == 0);
  
  		/* the last ref */
  		if (dest->ino_cache_inode) {
  			iput(dest->ino_cache_inode);
  			dest->ino_cache_inode = NULL;
  		}
  	}
  out_dput:
  	dput(dentry);
  out_unlock_dir:
  	inode_unlock(dir);
  out_drop_write:
  	mnt_drop_write_file(file);
  out:
  	kfree(vol_args);
  	return err;
  }
  
  static int btrfs_ioctl_defrag(struct file *file, void __user *argp)
  {
  	struct inode *inode = file_inode(file);
  	struct btrfs_root *root = BTRFS_I(inode)->root;
  	struct btrfs_ioctl_defrag_range_args *range;
  	int ret;
  
  	ret = mnt_want_write_file(file);
  	if (ret)
  		return ret;
  
  	if (btrfs_root_readonly(root)) {
  		ret = -EROFS;
  		goto out;
  	}
  
  	switch (inode->i_mode & S_IFMT) {
  	case S_IFDIR:
  		if (!capable(CAP_SYS_ADMIN)) {
  			ret = -EPERM;
  			goto out;
  		}
  		ret = btrfs_defrag_root(root);
  		break;
  	case S_IFREG:
  		if (!(file->f_mode & FMODE_WRITE)) {
  			ret = -EINVAL;
  			goto out;
  		}
  
  		range = kzalloc(sizeof(*range), GFP_KERNEL);
  		if (!range) {
  			ret = -ENOMEM;
  			goto out;
  		}
  
  		if (argp) {
  			if (copy_from_user(range, argp,
  					   sizeof(*range))) {
  				ret = -EFAULT;
  				kfree(range);
  				goto out;
  			}
  			/* compression requires us to start the IO */
  			if ((range->flags & BTRFS_DEFRAG_RANGE_COMPRESS)) {
  				range->flags |= BTRFS_DEFRAG_RANGE_START_IO;
  				range->extent_thresh = (u32)-1;
  			}
  		} else {
  			/* the rest are all set to zero by kzalloc */
  			range->len = (u64)-1;
  		}
  		ret = btrfs_defrag_file(file_inode(file), file,
  					range, 0, 0);
  		if (ret > 0)
  			ret = 0;
  		kfree(range);
  		break;
  	default:
  		ret = -EINVAL;
  	}
  out:
  	mnt_drop_write_file(file);
  	return ret;
  }
  
  static long btrfs_ioctl_add_dev(struct btrfs_fs_info *fs_info, void __user *arg)
  {
  	struct btrfs_ioctl_vol_args *vol_args;
  	int ret;
  
  	if (!capable(CAP_SYS_ADMIN))
  		return -EPERM;
  
  	if (test_and_set_bit(BTRFS_FS_EXCL_OP, &fs_info->flags))
  		return BTRFS_ERROR_DEV_EXCL_RUN_IN_PROGRESS;
  
  	mutex_lock(&fs_info->volume_mutex);
  	vol_args = memdup_user(arg, sizeof(*vol_args));
  	if (IS_ERR(vol_args)) {
  		ret = PTR_ERR(vol_args);
  		goto out;
  	}
  
  	vol_args->name[BTRFS_PATH_NAME_MAX] = '\0';
  	ret = btrfs_init_new_device(fs_info, vol_args->name);
  
  	if (!ret)
  		btrfs_info(fs_info, "disk added %s", vol_args->name);
  
  	kfree(vol_args);
  out:
  	mutex_unlock(&fs_info->volume_mutex);
  	clear_bit(BTRFS_FS_EXCL_OP, &fs_info->flags);
  	return ret;
  }
  
  static long btrfs_ioctl_rm_dev_v2(struct file *file, void __user *arg)
  {
  	struct inode *inode = file_inode(file);
  	struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
  	struct btrfs_ioctl_vol_args_v2 *vol_args;
  	int ret;
  
  	if (!capable(CAP_SYS_ADMIN))
  		return -EPERM;
  
  	ret = mnt_want_write_file(file);
  	if (ret)
  		return ret;
  
  	vol_args = memdup_user(arg, sizeof(*vol_args));
  	if (IS_ERR(vol_args)) {
  		ret = PTR_ERR(vol_args);
  		goto err_drop;
  	}
  
  	/* Check for compatibility reject unknown flags */
  	if (vol_args->flags & ~BTRFS_VOL_ARG_V2_FLAGS_SUPPORTED) {
  		ret = -EOPNOTSUPP;
  		goto out;
  	}
  
  	if (test_and_set_bit(BTRFS_FS_EXCL_OP, &fs_info->flags)) {
  		ret = BTRFS_ERROR_DEV_EXCL_RUN_IN_PROGRESS;
  		goto out;
  	}
  
  	mutex_lock(&fs_info->volume_mutex);
  	if (vol_args->flags & BTRFS_DEVICE_SPEC_BY_ID) {
  		ret = btrfs_rm_device(fs_info, NULL, vol_args->devid);
  	} else {
  		vol_args->name[BTRFS_SUBVOL_NAME_MAX] = '\0';
  		ret = btrfs_rm_device(fs_info, vol_args->name, 0);
  	}
  	mutex_unlock(&fs_info->volume_mutex);
  	clear_bit(BTRFS_FS_EXCL_OP, &fs_info->flags);
  
  	if (!ret) {
  		if (vol_args->flags & BTRFS_DEVICE_SPEC_BY_ID)
  			btrfs_info(fs_info, "device deleted: id %llu",
  					vol_args->devid);
  		else
  			btrfs_info(fs_info, "device deleted: %s",
  					vol_args->name);
  	}
  out:
  	kfree(vol_args);
  err_drop:
  	mnt_drop_write_file(file);
  	return ret;
  }
  
  static long btrfs_ioctl_rm_dev(struct file *file, void __user *arg)
  {
  	struct inode *inode = file_inode(file);
  	struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
  	struct btrfs_ioctl_vol_args *vol_args;
  	int ret;
  
  	if (!capable(CAP_SYS_ADMIN))
  		return -EPERM;
  
  	ret = mnt_want_write_file(file);
  	if (ret)
  		return ret;
  
  	if (test_and_set_bit(BTRFS_FS_EXCL_OP, &fs_info->flags)) {
  		ret = BTRFS_ERROR_DEV_EXCL_RUN_IN_PROGRESS;
  		goto out_drop_write;
  	}
  
  	vol_args = memdup_user(arg, sizeof(*vol_args));
  	if (IS_ERR(vol_args)) {
  		ret = PTR_ERR(vol_args);
  		goto out;
  	}
  
  	vol_args->name[BTRFS_PATH_NAME_MAX] = '\0';
  	mutex_lock(&fs_info->volume_mutex);
  	ret = btrfs_rm_device(fs_info, vol_args->name, 0);
  	mutex_unlock(&fs_info->volume_mutex);
  
  	if (!ret)
  		btrfs_info(fs_info, "disk deleted %s", vol_args->name);
  	kfree(vol_args);
  out:
  	clear_bit(BTRFS_FS_EXCL_OP, &fs_info->flags);
  out_drop_write:
  	mnt_drop_write_file(file);
  
  	return ret;
  }
  
  static long btrfs_ioctl_fs_info(struct btrfs_fs_info *fs_info,
  				void __user *arg)
  {
  	struct btrfs_ioctl_fs_info_args *fi_args;
  	struct btrfs_device *device;
  	struct btrfs_fs_devices *fs_devices = fs_info->fs_devices;
  	int ret = 0;
  
  	fi_args = kzalloc(sizeof(*fi_args), GFP_KERNEL);
  	if (!fi_args)
  		return -ENOMEM;
  
  	mutex_lock(&fs_devices->device_list_mutex);
  	fi_args->num_devices = fs_devices->num_devices;
  	memcpy(&fi_args->fsid, fs_info->fsid, sizeof(fi_args->fsid));
  
  	list_for_each_entry(device, &fs_devices->devices, dev_list) {
  		if (device->devid > fi_args->max_id)
  			fi_args->max_id = device->devid;
  	}
  	mutex_unlock(&fs_devices->device_list_mutex);
  
  	fi_args->nodesize = fs_info->nodesize;
  	fi_args->sectorsize = fs_info->sectorsize;
  	fi_args->clone_alignment = fs_info->sectorsize;
  
  	if (copy_to_user(arg, fi_args, sizeof(*fi_args)))
  		ret = -EFAULT;
  
  	kfree(fi_args);
  	return ret;
  }
  
  static long btrfs_ioctl_dev_info(struct btrfs_fs_info *fs_info,
  				 void __user *arg)
  {
  	struct btrfs_ioctl_dev_info_args *di_args;
  	struct btrfs_device *dev;
  	struct btrfs_fs_devices *fs_devices = fs_info->fs_devices;
  	int ret = 0;
  	char *s_uuid = NULL;
  
  	di_args = memdup_user(arg, sizeof(*di_args));
  	if (IS_ERR(di_args))
  		return PTR_ERR(di_args);
  
  	if (!btrfs_is_empty_uuid(di_args->uuid))
  		s_uuid = di_args->uuid;
  
  	mutex_lock(&fs_devices->device_list_mutex);
  	dev = btrfs_find_device(fs_info, di_args->devid, s_uuid, NULL);
  
  	if (!dev) {
  		ret = -ENODEV;
  		goto out;
  	}
  
  	di_args->devid = dev->devid;
  	di_args->bytes_used = btrfs_device_get_bytes_used(dev);
  	di_args->total_bytes = btrfs_device_get_total_bytes(dev);
  	memcpy(di_args->uuid, dev->uuid, sizeof(di_args->uuid));
  	if (dev->name) {
  		struct rcu_string *name;
  
  		rcu_read_lock();
  		name = rcu_dereference(dev->name);
  		strncpy(di_args->path, name->str, sizeof(di_args->path));
  		rcu_read_unlock();
  		di_args->path[sizeof(di_args->path) - 1] = 0;
  	} else {
  		di_args->path[0] = '\0';
  	}
  
  out:
  	mutex_unlock(&fs_devices->device_list_mutex);
  	if (ret == 0 && copy_to_user(arg, di_args, sizeof(*di_args)))
  		ret = -EFAULT;
  
  	kfree(di_args);
  	return ret;
  }
  
  static struct page *extent_same_get_page(struct inode *inode, pgoff_t index)
  {
  	struct page *page;
  
  	page = grab_cache_page(inode->i_mapping, index);
  	if (!page)
  		return ERR_PTR(-ENOMEM);
  
  	if (!PageUptodate(page)) {
  		int ret;
  
  		ret = btrfs_readpage(NULL, page);
  		if (ret)
  			return ERR_PTR(ret);
  		lock_page(page);
  		if (!PageUptodate(page)) {
  			unlock_page(page);
  			put_page(page);
  			return ERR_PTR(-EIO);
  		}
  		if (page->mapping != inode->i_mapping) {
  			unlock_page(page);
  			put_page(page);
  			return ERR_PTR(-EAGAIN);
  		}
  	}
  
  	return page;
  }
  
  static int gather_extent_pages(struct inode *inode, struct page **pages,
  			       int num_pages, u64 off)
  {
  	int i;
  	pgoff_t index = off >> PAGE_SHIFT;
  
  	for (i = 0; i < num_pages; i++) {
  again:
  		pages[i] = extent_same_get_page(inode, index + i);
  		if (IS_ERR(pages[i])) {
  			int err = PTR_ERR(pages[i]);
  
  			if (err == -EAGAIN)
  				goto again;
  			pages[i] = NULL;
  			return err;
  		}
  	}
  	return 0;
  }
  
  static int lock_extent_range(struct inode *inode, u64 off, u64 len,
  			     bool retry_range_locking)
  {
  	/*
  	 * Do any pending delalloc/csum calculations on inode, one way or
  	 * another, and lock file content.
  	 * The locking order is:
  	 *
  	 *   1) pages
  	 *   2) range in the inode's io tree
  	 */
  	while (1) {
  		struct btrfs_ordered_extent *ordered;
  		lock_extent(&BTRFS_I(inode)->io_tree, off, off + len - 1);
  		ordered = btrfs_lookup_first_ordered_extent(inode,
  							    off + len - 1);
  		if ((!ordered ||
  		     ordered->file_offset + ordered->len <= off ||
  		     ordered->file_offset >= off + len) &&
  		    !test_range_bit(&BTRFS_I(inode)->io_tree, off,
  				    off + len - 1, EXTENT_DELALLOC, 0, NULL)) {
  			if (ordered)
  				btrfs_put_ordered_extent(ordered);
  			break;
  		}
  		unlock_extent(&BTRFS_I(inode)->io_tree, off, off + len - 1);
  		if (ordered)
  			btrfs_put_ordered_extent(ordered);
  		if (!retry_range_locking)
  			return -EAGAIN;
  		btrfs_wait_ordered_range(inode, off, len);
  	}
  	return 0;
  }
  
  static void btrfs_double_inode_unlock(struct inode *inode1, struct inode *inode2)
  {
  	inode_unlock(inode1);
  	inode_unlock(inode2);
  }
  
  static void btrfs_double_inode_lock(struct inode *inode1, struct inode *inode2)
  {
  	if (inode1 < inode2)
  		swap(inode1, inode2);
  
  	inode_lock_nested(inode1, I_MUTEX_PARENT);
  	inode_lock_nested(inode2, I_MUTEX_CHILD);
  }
  
  static void btrfs_double_extent_unlock(struct inode *inode1, u64 loff1,
  				      struct inode *inode2, u64 loff2, u64 len)
  {
  	unlock_extent(&BTRFS_I(inode1)->io_tree, loff1, loff1 + len - 1);
  	unlock_extent(&BTRFS_I(inode2)->io_tree, loff2, loff2 + len - 1);
  }
  
  static int btrfs_double_extent_lock(struct inode *inode1, u64 loff1,
  				    struct inode *inode2, u64 loff2, u64 len,
  				    bool retry_range_locking)
  {
  	int ret;
  
  	if (inode1 < inode2) {
  		swap(inode1, inode2);
  		swap(loff1, loff2);
  	}
  	ret = lock_extent_range(inode1, loff1, len, retry_range_locking);
  	if (ret)
  		return ret;
  	ret = lock_extent_range(inode2, loff2, len, retry_range_locking);
  	if (ret)
  		unlock_extent(&BTRFS_I(inode1)->io_tree, loff1,
  			      loff1 + len - 1);
  	return ret;
  }
  
  struct cmp_pages {
  	int		num_pages;
  	struct page	**src_pages;
  	struct page	**dst_pages;
  };
  
  static void btrfs_cmp_data_free(struct cmp_pages *cmp)
  {
  	int i;
  	struct page *pg;
  
  	for (i = 0; i < cmp->num_pages; i++) {
  		pg = cmp->src_pages[i];
  		if (pg) {
  			unlock_page(pg);
  			put_page(pg);
  		}
  		pg = cmp->dst_pages[i];
  		if (pg) {
  			unlock_page(pg);
  			put_page(pg);
  		}
  	}
  	kfree(cmp->src_pages);
  	kfree(cmp->dst_pages);
  }
  
  static int btrfs_cmp_data_prepare(struct inode *src, u64 loff,
  				  struct inode *dst, u64 dst_loff,
  				  u64 len, struct cmp_pages *cmp)
  {
  	int ret;
  	int num_pages = PAGE_ALIGN(len) >> PAGE_SHIFT;
  	struct page **src_pgarr, **dst_pgarr;
  
  	/*
  	 * We must gather up all the pages before we initiate our
  	 * extent locking. We use an array for the page pointers. Size
  	 * of the array is bounded by len, which is in turn bounded by
  	 * BTRFS_MAX_DEDUPE_LEN.
  	 */
  	src_pgarr = kcalloc(num_pages, sizeof(struct page *), GFP_KERNEL);
  	dst_pgarr = kcalloc(num_pages, sizeof(struct page *), GFP_KERNEL);
  	if (!src_pgarr || !dst_pgarr) {
  		kfree(src_pgarr);
  		kfree(dst_pgarr);
  		return -ENOMEM;
  	}
  	cmp->num_pages = num_pages;
  	cmp->src_pages = src_pgarr;
  	cmp->dst_pages = dst_pgarr;
  
  	/*
  	 * If deduping ranges in the same inode, locking rules make it mandatory
  	 * to always lock pages in ascending order to avoid deadlocks with
  	 * concurrent tasks (such as starting writeback/delalloc).
  	 */
  	if (src == dst && dst_loff < loff) {
  		swap(src_pgarr, dst_pgarr);
  		swap(loff, dst_loff);
  	}
  
  	ret = gather_extent_pages(src, src_pgarr, cmp->num_pages, loff);
  	if (ret)
  		goto out;
  
  	ret = gather_extent_pages(dst, dst_pgarr, cmp->num_pages, dst_loff);
  
  out:
  	if (ret)
  		btrfs_cmp_data_free(cmp);
  	return ret;
  }
  
  static int btrfs_cmp_data(u64 len, struct cmp_pages *cmp)
  {
  	int ret = 0;
  	int i;
  	struct page *src_page, *dst_page;
  	unsigned int cmp_len = PAGE_SIZE;
  	void *addr, *dst_addr;
  
  	i = 0;
  	while (len) {
  		if (len < PAGE_SIZE)
  			cmp_len = len;
  
  		BUG_ON(i >= cmp->num_pages);
  
  		src_page = cmp->src_pages[i];
  		dst_page = cmp->dst_pages[i];
  		ASSERT(PageLocked(src_page));
  		ASSERT(PageLocked(dst_page));
  
  		addr = kmap_atomic(src_page);
  		dst_addr = kmap_atomic(dst_page);
  
  		flush_dcache_page(src_page);
  		flush_dcache_page(dst_page);
  
  		if (memcmp(addr, dst_addr, cmp_len))
  			ret = -EBADE;
  
  		kunmap_atomic(addr);
  		kunmap_atomic(dst_addr);
  
  		if (ret)
  			break;
  
  		len -= cmp_len;
  		i++;
  	}
  
  	return ret;
  }
  
  static int extent_same_check_offsets(struct inode *inode, u64 off, u64 *plen,
  				     u64 olen)
  {
  	u64 len = *plen;
  	u64 bs = BTRFS_I(inode)->root->fs_info->sb->s_blocksize;
  
  	if (off + olen > inode->i_size || off + olen < off)
  		return -EINVAL;
  
  	/* if we extend to eof, continue to block boundary */
  	if (off + len == inode->i_size)
  		*plen = len = ALIGN(inode->i_size, bs) - off;
  
  	/* Check that we are block aligned - btrfs_clone() requires this */
  	if (!IS_ALIGNED(off, bs) || !IS_ALIGNED(off + len, bs))
  		return -EINVAL;
  
  	return 0;
  }
  
  static int btrfs_extent_same(struct inode *src, u64 loff, u64 olen,
  			     struct inode *dst, u64 dst_loff)
  {
  	int ret;
  	u64 len = olen;
  	struct cmp_pages cmp;
  	bool same_inode = (src == dst);
  	u64 same_lock_start = 0;
  	u64 same_lock_len = 0;
  
  	if (len == 0)
  		return 0;
  
  	if (same_inode)
  		inode_lock(src);
  	else
  		btrfs_double_inode_lock(src, dst);
  
  	ret = extent_same_check_offsets(src, loff, &len, olen);
  	if (ret)
  		goto out_unlock;
  
  	ret = extent_same_check_offsets(dst, dst_loff, &len, olen);
  	if (ret)
  		goto out_unlock;
  
  	if (same_inode) {
  		/*
  		 * Single inode case wants the same checks, except we
  		 * don't want our length pushed out past i_size as
  		 * comparing that data range makes no sense.
  		 *
  		 * extent_same_check_offsets() will do this for an
  		 * unaligned length at i_size, so catch it here and
  		 * reject the request.
  		 *
  		 * This effectively means we require aligned extents
  		 * for the single-inode case, whereas the other cases
  		 * allow an unaligned length so long as it ends at
  		 * i_size.
  		 */
  		if (len != olen) {
  			ret = -EINVAL;
  			goto out_unlock;
  		}
  
  		/* Check for overlapping ranges */
  		if (dst_loff + len > loff && dst_loff < loff + len) {
  			ret = -EINVAL;
  			goto out_unlock;
  		}
  
  		same_lock_start = min_t(u64, loff, dst_loff);
  		same_lock_len = max_t(u64, loff, dst_loff) + len - same_lock_start;
  	} else {
  		/*
  		 * If the source and destination inodes are different, the
  		 * source's range end offset matches the source's i_size, that
  		 * i_size is not a multiple of the sector size, and the
  		 * destination range does not go past the destination's i_size,
  		 * we must round down the length to the nearest sector size
  		 * multiple. If we don't do this adjustment we end replacing
  		 * with zeroes the bytes in the range that starts at the
  		 * deduplication range's end offset and ends at the next sector
  		 * size multiple.
  		 */
  		if (loff + olen == i_size_read(src) &&
  		    dst_loff + len < i_size_read(dst)) {
  			const u64 sz = BTRFS_I(src)->root->fs_info->sectorsize;
  
  			len = round_down(i_size_read(src), sz) - loff;
  			if (len == 0)
  				return 0;
  			olen = len;
  		}
  	}
  
  	/* don't make the dst file partly checksummed */
  	if ((BTRFS_I(src)->flags & BTRFS_INODE_NODATASUM) !=
  	    (BTRFS_I(dst)->flags & BTRFS_INODE_NODATASUM)) {
  		ret = -EINVAL;
  		goto out_unlock;
  	}
  
  again:
  	ret = btrfs_cmp_data_prepare(src, loff, dst, dst_loff, olen, &cmp);
  	if (ret)
  		goto out_unlock;
  
  	if (same_inode)
  		ret = lock_extent_range(src, same_lock_start, same_lock_len,
  					false);
  	else
  		ret = btrfs_double_extent_lock(src, loff, dst, dst_loff, len,
  					       false);
  	/*
  	 * If one of the inodes has dirty pages in the respective range or
  	 * ordered extents, we need to flush dellaloc and wait for all ordered
  	 * extents in the range. We must unlock the pages and the ranges in the
  	 * io trees to avoid deadlocks when flushing delalloc (requires locking
  	 * pages) and when waiting for ordered extents to complete (they require
  	 * range locking).
  	 */
  	if (ret == -EAGAIN) {
  		/*
  		 * Ranges in the io trees already unlocked. Now unlock all
  		 * pages before waiting for all IO to complete.
  		 */
  		btrfs_cmp_data_free(&cmp);
  		if (same_inode) {
  			btrfs_wait_ordered_range(src, same_lock_start,
  						 same_lock_len);
  		} else {
  			btrfs_wait_ordered_range(src, loff, len);
  			btrfs_wait_ordered_range(dst, dst_loff, len);
  		}
  		goto again;
  	}
  	ASSERT(ret == 0);
  	if (WARN_ON(ret)) {
  		/* ranges in the io trees already unlocked */
  		btrfs_cmp_data_free(&cmp);
  		return ret;
  	}
  
  	/* pass original length for comparison so we stay within i_size */
  	ret = btrfs_cmp_data(olen, &cmp);
  	if (ret == 0)
  		ret = btrfs_clone(src, dst, loff, olen, len, dst_loff, 1);
  
  	if (same_inode)
  		unlock_extent(&BTRFS_I(src)->io_tree, same_lock_start,
  			      same_lock_start + same_lock_len - 1);
  	else
  		btrfs_double_extent_unlock(src, loff, dst, dst_loff, len);
  
  	btrfs_cmp_data_free(&cmp);
  out_unlock:
  	if (same_inode)
  		inode_unlock(src);
  	else
  		btrfs_double_inode_unlock(src, dst);
  
  	return ret;
  }
  
  #define BTRFS_MAX_DEDUPE_LEN	SZ_16M
  
  ssize_t btrfs_dedupe_file_range(struct file *src_file, u64 loff, u64 olen,
  				struct file *dst_file, u64 dst_loff)
  {
  	struct inode *src = file_inode(src_file);
  	struct inode *dst = file_inode(dst_file);
  	u64 bs = BTRFS_I(src)->root->fs_info->sb->s_blocksize;
  	ssize_t res;
  
  	if (olen > BTRFS_MAX_DEDUPE_LEN)
  		olen = BTRFS_MAX_DEDUPE_LEN;
  
  	if (WARN_ON_ONCE(bs < PAGE_SIZE)) {
  		/*
  		 * Btrfs does not support blocksize < page_size. As a
  		 * result, btrfs_cmp_data() won't correctly handle
  		 * this situation without an update.
  		 */
  		return -EINVAL;
  	}
  
  	res = btrfs_extent_same(src, loff, olen, dst, dst_loff);
  	if (res)
  		return res;
  	return olen;
  }
  
  static int clone_finish_inode_update(struct btrfs_trans_handle *trans,
  				     struct inode *inode,
  				     u64 endoff,
  				     const u64 destoff,
  				     const u64 olen,
  				     int no_time_update)
  {
  	struct btrfs_root *root = BTRFS_I(inode)->root;
  	int ret;
  
  	inode_inc_iversion(inode);
  	if (!no_time_update)
  		inode->i_mtime = inode->i_ctime = current_time(inode);
  	/*
  	 * We round up to the block size at eof when determining which
  	 * extents to clone above, but shouldn't round up the file size.
  	 */
  	if (endoff > destoff + olen)
  		endoff = destoff + olen;
  	if (endoff > inode->i_size)
  		btrfs_i_size_write(BTRFS_I(inode), endoff);
  
  	ret = btrfs_update_inode(trans, root, inode);
  	if (ret) {
  		btrfs_abort_transaction(trans, ret);
  		btrfs_end_transaction(trans);
  		goto out;
  	}
  	ret = btrfs_end_transaction(trans);
  out:
  	return ret;
  }
  
  static void clone_update_extent_map(struct btrfs_inode *inode,
  				    const struct btrfs_trans_handle *trans,
  				    const struct btrfs_path *path,
  				    const u64 hole_offset,
  				    const u64 hole_len)
  {
  	struct extent_map_tree *em_tree = &inode->extent_tree;
  	struct extent_map *em;
  	int ret;
  
  	em = alloc_extent_map();
  	if (!em) {
  		set_bit(BTRFS_INODE_NEEDS_FULL_SYNC, &inode->runtime_flags);
  		return;
  	}
  
  	if (path) {
  		struct btrfs_file_extent_item *fi;
  
  		fi = btrfs_item_ptr(path->nodes[0], path->slots[0],
  				    struct btrfs_file_extent_item);
  		btrfs_extent_item_to_extent_map(inode, path, fi, false, em);
  		em->generation = -1;
  		if (btrfs_file_extent_type(path->nodes[0], fi) ==
  		    BTRFS_FILE_EXTENT_INLINE)
  			set_bit(BTRFS_INODE_NEEDS_FULL_SYNC,
  					&inode->runtime_flags);
  	} else {
  		em->start = hole_offset;
  		em->len = hole_len;
  		em->ram_bytes = em->len;
  		em->orig_start = hole_offset;
  		em->block_start = EXTENT_MAP_HOLE;
  		em->block_len = 0;
  		em->orig_block_len = 0;
  		em->compress_type = BTRFS_COMPRESS_NONE;
  		em->generation = trans->transid;
  	}
  
  	while (1) {
  		write_lock(&em_tree->lock);
  		ret = add_extent_mapping(em_tree, em, 1);
  		write_unlock(&em_tree->lock);
  		if (ret != -EEXIST) {
  			free_extent_map(em);
  			break;
  		}
  		btrfs_drop_extent_cache(inode, em->start,
  					em->start + em->len - 1, 0);
  	}
  
  	if (ret)
  		set_bit(BTRFS_INODE_NEEDS_FULL_SYNC, &inode->runtime_flags);
  }
  
  /*
   * Make sure we do not end up inserting an inline extent into a file that has
   * already other (non-inline) extents. If a file has an inline extent it can
   * not have any other extents and the (single) inline extent must start at the
   * file offset 0. Failing to respect these rules will lead to file corruption,
   * resulting in EIO errors on read/write operations, hitting BUG_ON's in mm, etc
   *
   * We can have extents that have been already written to disk or we can have
   * dirty ranges still in delalloc, in which case the extent maps and items are
   * created only when we run delalloc, and the delalloc ranges might fall outside
   * the range we are currently locking in the inode's io tree. So we check the
   * inode's i_size because of that (i_size updates are done while holding the
   * i_mutex, which we are holding here).
   * We also check to see if the inode has a size not greater than "datal" but has
   * extents beyond it, due to an fallocate with FALLOC_FL_KEEP_SIZE (and we are
   * protected against such concurrent fallocate calls by the i_mutex).
   *
   * If the file has no extents but a size greater than datal, do not allow the
   * copy because we would need turn the inline extent into a non-inline one (even
   * with NO_HOLES enabled). If we find our destination inode only has one inline
   * extent, just overwrite it with the source inline extent if its size is less
   * than the source extent's size, or we could copy the source inline extent's
   * data into the destination inode's inline extent if the later is greater then
   * the former.
   */
  static int clone_copy_inline_extent(struct inode *dst,
  				    struct btrfs_trans_handle *trans,
  				    struct btrfs_path *path,
  				    struct btrfs_key *new_key,
  				    const u64 drop_start,
  				    const u64 datal,
  				    const u64 skip,
  				    const u64 size,
  				    char *inline_data)
  {
  	struct btrfs_fs_info *fs_info = btrfs_sb(dst->i_sb);
  	struct btrfs_root *root = BTRFS_I(dst)->root;
  	const u64 aligned_end = ALIGN(new_key->offset + datal,
  				      fs_info->sectorsize);
  	int ret;
  	struct btrfs_key key;
  
  	if (new_key->offset > 0)
  		return -EOPNOTSUPP;
  
  	key.objectid = btrfs_ino(BTRFS_I(dst));
  	key.type = BTRFS_EXTENT_DATA_KEY;
  	key.offset = 0;
  	ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
  	if (ret < 0) {
  		return ret;
  	} else if (ret > 0) {
  		if (path->slots[0] >= btrfs_header_nritems(path->nodes[0])) {
  			ret = btrfs_next_leaf(root, path);
  			if (ret < 0)
  				return ret;
  			else if (ret > 0)
  				goto copy_inline_extent;
  		}
  		btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
  		if (key.objectid == btrfs_ino(BTRFS_I(dst)) &&
  		    key.type == BTRFS_EXTENT_DATA_KEY) {
  			ASSERT(key.offset > 0);
  			return -EOPNOTSUPP;
  		}
  	} else if (i_size_read(dst) <= datal) {
  		struct btrfs_file_extent_item *ei;
  		u64 ext_len;
  
  		/*
  		 * If the file size is <= datal, make sure there are no other
  		 * extents following (can happen do to an fallocate call with
  		 * the flag FALLOC_FL_KEEP_SIZE).
  		 */
  		ei = btrfs_item_ptr(path->nodes[0], path->slots[0],
  				    struct btrfs_file_extent_item);
  		/*
  		 * If it's an inline extent, it can not have other extents
  		 * following it.
  		 */
  		if (btrfs_file_extent_type(path->nodes[0], ei) ==
  		    BTRFS_FILE_EXTENT_INLINE)
  			goto copy_inline_extent;
  
  		ext_len = btrfs_file_extent_num_bytes(path->nodes[0], ei);
  		if (ext_len > aligned_end)
  			return -EOPNOTSUPP;
  
  		ret = btrfs_next_item(root, path);
  		if (ret < 0) {
  			return ret;
  		} else if (ret == 0) {
  			btrfs_item_key_to_cpu(path->nodes[0], &key,
  					      path->slots[0]);
  			if (key.objectid == btrfs_ino(BTRFS_I(dst)) &&
  			    key.type == BTRFS_EXTENT_DATA_KEY)
  				return -EOPNOTSUPP;
  		}
  	}
  
  copy_inline_extent:
  	/*
  	 * We have no extent items, or we have an extent at offset 0 which may
  	 * or may not be inlined. All these cases are dealt the same way.
  	 */
  	if (i_size_read(dst) > datal) {
  		/*
  		 * If the destination inode has an inline extent...
  		 * This would require copying the data from the source inline
  		 * extent into the beginning of the destination's inline extent.
  		 * But this is really complex, both extents can be compressed
  		 * or just one of them, which would require decompressing and
  		 * re-compressing data (which could increase the new compressed
  		 * size, not allowing the compressed data to fit anymore in an
  		 * inline extent).
  		 * So just don't support this case for now (it should be rare,
  		 * we are not really saving space when cloning inline extents).
  		 */
  		return -EOPNOTSUPP;
  	}
  
  	btrfs_release_path(path);
  	ret = btrfs_drop_extents(trans, root, dst, drop_start, aligned_end, 1);
  	if (ret)
  		return ret;
  	ret = btrfs_insert_empty_item(trans, root, path, new_key, size);
  	if (ret)
  		return ret;
  
  	if (skip) {
  		const u32 start = btrfs_file_extent_calc_inline_size(0);
  
  		memmove(inline_data + start, inline_data + start + skip, datal);
  	}
  
  	write_extent_buffer(path->nodes[0], inline_data,
  			    btrfs_item_ptr_offset(path->nodes[0],
  						  path->slots[0]),
  			    size);
  	inode_add_bytes(dst, datal);
  
  	return 0;
  }
  
  /**
   * btrfs_clone() - clone a range from inode file to another
   *
   * @src: Inode to clone from
   * @inode: Inode to clone to
   * @off: Offset within source to start clone from
   * @olen: Original length, passed by user, of range to clone
   * @olen_aligned: Block-aligned value of olen
   * @destoff: Offset within @inode to start clone
   * @no_time_update: Whether to update mtime/ctime on the target inode
   */
  static int btrfs_clone(struct inode *src, struct inode *inode,
  		       const u64 off, const u64 olen, const u64 olen_aligned,
  		       const u64 destoff, int no_time_update)
  {
  	struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
  	struct btrfs_root *root = BTRFS_I(inode)->root;
  	struct btrfs_path *path = NULL;
  	struct extent_buffer *leaf;
  	struct btrfs_trans_handle *trans;
  	char *buf = NULL;
  	struct btrfs_key key;
  	u32 nritems;
  	int slot;
  	int ret;
  	const u64 len = olen_aligned;
  	u64 last_dest_end = destoff;
  
  	ret = -ENOMEM;
  	buf = kvmalloc(fs_info->nodesize, GFP_KERNEL);
  	if (!buf)
  		return ret;
  
  	path = btrfs_alloc_path();
  	if (!path) {
  		kvfree(buf);
  		return ret;
  	}
  
  	path->reada = READA_FORWARD;
  	/* clone data */
  	key.objectid = btrfs_ino(BTRFS_I(src));
  	key.type = BTRFS_EXTENT_DATA_KEY;
  	key.offset = off;
  
  	while (1) {
  		u64 next_key_min_offset = key.offset + 1;
  
  		/*
  		 * note the key will change type as we walk through the
  		 * tree.
  		 */
  		path->leave_spinning = 1;
  		ret = btrfs_search_slot(NULL, BTRFS_I(src)->root, &key, path,
  				0, 0);
  		if (ret < 0)
  			goto out;
  		/*
  		 * First search, if no extent item that starts at offset off was
  		 * found but the previous item is an extent item, it's possible
  		 * it might overlap our target range, therefore process it.
  		 */
  		if (key.offset == off && ret > 0 && path->slots[0] > 0) {
  			btrfs_item_key_to_cpu(path->nodes[0], &key,
  					      path->slots[0] - 1);
  			if (key.type == BTRFS_EXTENT_DATA_KEY)
  				path->slots[0]--;
  		}
  
  		nritems = btrfs_header_nritems(path->nodes[0]);
  process_slot:
  		if (path->slots[0] >= nritems) {
  			ret = btrfs_next_leaf(BTRFS_I(src)->root, path);
  			if (ret < 0)
  				goto out;
  			if (ret > 0)
  				break;
  			nritems = btrfs_header_nritems(path->nodes[0]);
  		}
  		leaf = path->nodes[0];
  		slot = path->slots[0];
  
  		btrfs_item_key_to_cpu(leaf, &key, slot);
  		if (key.type > BTRFS_EXTENT_DATA_KEY ||
  		    key.objectid != btrfs_ino(BTRFS_I(src)))
  			break;
  
  		if (key.type == BTRFS_EXTENT_DATA_KEY) {
  			struct btrfs_file_extent_item *extent;
  			int type;
  			u32 size;
  			struct btrfs_key new_key;
  			u64 disko = 0, diskl = 0;
  			u64 datao = 0, datal = 0;
  			u8 comp;
  			u64 drop_start;
  
  			extent = btrfs_item_ptr(leaf, slot,
  						struct btrfs_file_extent_item);
  			comp = btrfs_file_extent_compression(leaf, extent);
  			type = btrfs_file_extent_type(leaf, extent);
  			if (type == BTRFS_FILE_EXTENT_REG ||
  			    type == BTRFS_FILE_EXTENT_PREALLOC) {
  				disko = btrfs_file_extent_disk_bytenr(leaf,
  								      extent);
  				diskl = btrfs_file_extent_disk_num_bytes(leaf,
  								 extent);
  				datao = btrfs_file_extent_offset(leaf, extent);
  				datal = btrfs_file_extent_num_bytes(leaf,
  								    extent);
  			} else if (type == BTRFS_FILE_EXTENT_INLINE) {
  				/* take upper bound, may be compressed */
  				datal = btrfs_file_extent_ram_bytes(leaf,
  								    extent);
  			}
  
  			/*
  			 * The first search might have left us at an extent
  			 * item that ends before our target range's start, can
  			 * happen if we have holes and NO_HOLES feature enabled.
  			 */
  			if (key.offset + datal <= off) {
  				path->slots[0]++;
  				goto process_slot;
  			} else if (key.offset >= off + len) {
  				break;
  			}
  			next_key_min_offset = key.offset + datal;
  			size = btrfs_item_size_nr(leaf, slot);
  			read_extent_buffer(leaf, buf,
  					   btrfs_item_ptr_offset(leaf, slot),
  					   size);
  
  			btrfs_release_path(path);
  			path->leave_spinning = 0;
  
  			memcpy(&new_key, &key, sizeof(new_key));
  			new_key.objectid = btrfs_ino(BTRFS_I(inode));
  			if (off <= key.offset)
  				new_key.offset = key.offset + destoff - off;
  			else
  				new_key.offset = destoff;
  
  			/*
  			 * Deal with a hole that doesn't have an extent item
  			 * that represents it (NO_HOLES feature enabled).
  			 * This hole is either in the middle of the cloning
  			 * range or at the beginning (fully overlaps it or
  			 * partially overlaps it).
  			 */
  			if (new_key.offset != last_dest_end)
  				drop_start = last_dest_end;
  			else
  				drop_start = new_key.offset;
  
  			/*
  			 * 1 - adjusting old extent (we may have to split it)
  			 * 1 - add new extent
  			 * 1 - inode update
  			 */
  			trans = btrfs_start_transaction(root, 3);
  			if (IS_ERR(trans)) {
  				ret = PTR_ERR(trans);
  				goto out;
  			}
  
  			if (type == BTRFS_FILE_EXTENT_REG ||
  			    type == BTRFS_FILE_EXTENT_PREALLOC) {
  				/*
  				 *    a  | --- range to clone ---|  b
  				 * | ------------- extent ------------- |
  				 */
  
  				/* subtract range b */
  				if (key.offset + datal > off + len)
  					datal = off + len - key.offset;
  
  				/* subtract range a */
  				if (off > key.offset) {
  					datao += off - key.offset;
  					datal -= off - key.offset;
  				}
  
  				ret = btrfs_drop_extents(trans, root, inode,
  							 drop_start,
  							 new_key.offset + datal,
  							 1);
  				if (ret) {
  					if (ret != -EOPNOTSUPP)
  						btrfs_abort_transaction(trans,
  									ret);
  					btrfs_end_transaction(trans);
  					goto out;
  				}
  
  				ret = btrfs_insert_empty_item(trans, root, path,
  							      &new_key, size);
  				if (ret) {
  					btrfs_abort_transaction(trans, ret);
  					btrfs_end_transaction(trans);
  					goto out;
  				}
  
  				leaf = path->nodes[0];
  				slot = path->slots[0];
  				write_extent_buffer(leaf, buf,
  					    btrfs_item_ptr_offset(leaf, slot),
  					    size);
  
  				extent = btrfs_item_ptr(leaf, slot,
  						struct btrfs_file_extent_item);
  
  				/* disko == 0 means it's a hole */
  				if (!disko)
  					datao = 0;
  
  				btrfs_set_file_extent_offset(leaf, extent,
  							     datao);
  				btrfs_set_file_extent_num_bytes(leaf, extent,
  								datal);
  
  				if (disko) {
  					inode_add_bytes(inode, datal);
  					ret = btrfs_inc_extent_ref(trans,
  							fs_info,
  							disko, diskl, 0,
  							root->root_key.objectid,
  							btrfs_ino(BTRFS_I(inode)),
  							new_key.offset - datao);
  					if (ret) {
  						btrfs_abort_transaction(trans,
  									ret);
  						btrfs_end_transaction(trans);
  						goto out;
  
  					}
  				}
  			} else if (type == BTRFS_FILE_EXTENT_INLINE) {
  				u64 skip = 0;
  				u64 trim = 0;
  
  				if (off > key.offset) {
  					skip = off - key.offset;
  					new_key.offset += skip;
  				}
  
  				if (key.offset + datal > off + len)
  					trim = key.offset + datal - (off + len);
  
  				if (comp && (skip || trim)) {
  					ret = -EINVAL;
  					btrfs_end_transaction(trans);
  					goto out;
  				}
  				size -= skip + trim;
  				datal -= skip + trim;
  
  				ret = clone_copy_inline_extent(inode,
  							       trans, path,
  							       &new_key,
  							       drop_start,
  							       datal,
  							       skip, size, buf);
  				if (ret) {
  					if (ret != -EOPNOTSUPP)
  						btrfs_abort_transaction(trans,
  									ret);
  					btrfs_end_transaction(trans);
  					goto out;
  				}
  				leaf = path->nodes[0];
  				slot = path->slots[0];
  			}
  
  			/* If we have an implicit hole (NO_HOLES feature). */
  			if (drop_start < new_key.offset)
  				clone_update_extent_map(BTRFS_I(inode), trans,
  						NULL, drop_start,
  						new_key.offset - drop_start);
  
  			clone_update_extent_map(BTRFS_I(inode), trans,
  					path, 0, 0);
  
  			btrfs_mark_buffer_dirty(leaf);
  			btrfs_release_path(path);
  
  			last_dest_end = ALIGN(new_key.offset + datal,
  					      fs_info->sectorsize);
  			ret = clone_finish_inode_update(trans, inode,
  							last_dest_end,
  							destoff, olen,
  							no_time_update);
  			if (ret)
  				goto out;
  			if (new_key.offset + datal >= destoff + len)
  				break;
  		}
  		btrfs_release_path(path);
  		key.offset = next_key_min_offset;
  
  		if (fatal_signal_pending(current)) {
  			ret = -EINTR;
  			goto out;
  		}
  	}
  	ret = 0;
  
  	if (last_dest_end < destoff + len) {
  		/*
  		 * We have an implicit hole (NO_HOLES feature is enabled) that
  		 * fully or partially overlaps our cloning range at its end.
  		 */
  		btrfs_release_path(path);
  
  		/*
  		 * 1 - remove extent(s)
  		 * 1 - inode update
  		 */
  		trans = btrfs_start_transaction(root, 2);
  		if (IS_ERR(trans)) {
  			ret = PTR_ERR(trans);
  			goto out;
  		}
  		ret = btrfs_drop_extents(trans, root, inode,
  					 last_dest_end, destoff + len, 1);
  		if (ret) {
  			if (ret != -EOPNOTSUPP)
  				btrfs_abort_transaction(trans, ret);
  			btrfs_end_transaction(trans);
  			goto out;
  		}
  		clone_update_extent_map(BTRFS_I(inode), trans, NULL,
  				last_dest_end,
  				destoff + len - last_dest_end);
  		ret = clone_finish_inode_update(trans, inode, destoff + len,
  						destoff, olen, no_time_update);
  	}
  
  out:
  	btrfs_free_path(path);
  	kvfree(buf);
  	return ret;
  }
  
  static noinline int btrfs_clone_files(struct file *file, struct file *file_src,
  					u64 off, u64 olen, u64 destoff)
  {
  	struct inode *inode = file_inode(file);
  	struct inode *src = file_inode(file_src);
  	struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
  	struct btrfs_root *root = BTRFS_I(inode)->root;
  	int ret;
  	u64 len = olen;
  	u64 bs = fs_info->sb->s_blocksize;
  	int same_inode = src == inode;
  
  	/*
  	 * TODO:
  	 * - split compressed inline extents.  annoying: we need to
  	 *   decompress into destination's address_space (the file offset
  	 *   may change, so source mapping won't do), then recompress (or
  	 *   otherwise reinsert) a subrange.
  	 *
  	 * - split destination inode's inline extents.  The inline extents can
  	 *   be either compressed or non-compressed.
  	 */
  
  	if (btrfs_root_readonly(root))
  		return -EROFS;
  
  	if (file_src->f_path.mnt != file->f_path.mnt ||
  	    src->i_sb != inode->i_sb)
  		return -EXDEV;
  
  	if (S_ISDIR(src->i_mode) || S_ISDIR(inode->i_mode))
  		return -EISDIR;
  
  	if (!same_inode) {
  		btrfs_double_inode_lock(src, inode);
  	} else {
  		inode_lock(src);
  	}
  
  	/* don't make the dst file partly checksummed */
  	if ((BTRFS_I(src)->flags & BTRFS_INODE_NODATASUM) !=
  	    (BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM)) {
  		ret = -EINVAL;
  		goto out_unlock;
  	}
  
  	/* determine range to clone */
  	ret = -EINVAL;
  	if (off + len > src->i_size || off + len < off)
  		goto out_unlock;
  	if (len == 0)
  		olen = len = src->i_size - off;
  	/*
  	 * If we extend to eof, continue to block boundary if and only if the
  	 * destination end offset matches the destination file's size, otherwise
  	 * we would be corrupting data by placing the eof block into the middle
  	 * of a file.
  	 */
  	if (off + len == src->i_size) {
  		if (!IS_ALIGNED(len, bs) && destoff + len < inode->i_size)
  			goto out_unlock;
  		len = ALIGN(src->i_size, bs) - off;
  	}
  
  	if (len == 0) {
  		ret = 0;
  		goto out_unlock;
  	}
  
  	/* verify the end result is block aligned */
  	if (!IS_ALIGNED(off, bs) || !IS_ALIGNED(off + len, bs) ||
  	    !IS_ALIGNED(destoff, bs))
  		goto out_unlock;
  
  	/* verify if ranges are overlapped within the same file */
  	if (same_inode) {
  		if (destoff + len > off && destoff < off + len)
  			goto out_unlock;
  	}
  
  	if (destoff > inode->i_size) {
  		ret = btrfs_cont_expand(inode, inode->i_size, destoff);
  		if (ret)
  			goto out_unlock;
  	}
  
  	/*
  	 * Lock the target range too. Right after we replace the file extent
  	 * items in the fs tree (which now point to the cloned data), we might
  	 * have a worker replace them with extent items relative to a write
  	 * operation that was issued before this clone operation (i.e. confront
  	 * with inode.c:btrfs_finish_ordered_io).
  	 */
  	if (same_inode) {
  		u64 lock_start = min_t(u64, off, destoff);
  		u64 lock_len = max_t(u64, off, destoff) + len - lock_start;
  
  		ret = lock_extent_range(src, lock_start, lock_len, true);
  	} else {
  		ret = btrfs_double_extent_lock(src, off, inode, destoff, len,
  					       true);
  	}
  	ASSERT(ret == 0);
  	if (WARN_ON(ret)) {
  		/* ranges in the io trees already unlocked */
  		goto out_unlock;
  	}
  
  	ret = btrfs_clone(src, inode, off, olen, len, destoff, 0);
  
  	if (same_inode) {
  		u64 lock_start = min_t(u64, off, destoff);
  		u64 lock_end = max_t(u64, off, destoff) + len - 1;
  
  		unlock_extent(&BTRFS_I(src)->io_tree, lock_start, lock_end);
  	} else {
  		btrfs_double_extent_unlock(src, off, inode, destoff, len);
  	}
  	/*
  	 * Truncate page cache pages so that future reads will see the cloned
  	 * data immediately and not the previous data.
  	 */
  	truncate_inode_pages_range(&inode->i_data,
  				round_down(destoff, PAGE_SIZE),
  				round_up(destoff + len, PAGE_SIZE) - 1);
  out_unlock:
  	if (!same_inode)
  		btrfs_double_inode_unlock(src, inode);
  	else
  		inode_unlock(src);
  	return ret;
  }
  
  int btrfs_clone_file_range(struct file *src_file, loff_t off,
  		struct file *dst_file, loff_t destoff, u64 len)
  {
  	return btrfs_clone_files(dst_file, src_file, off, len, destoff);
  }
  
  /*
   * there are many ways the trans_start and trans_end ioctls can lead
   * to deadlocks.  They should only be used by applications that
   * basically own the machine, and have a very in depth understanding
   * of all the possible deadlocks and enospc problems.
   */
  static long btrfs_ioctl_trans_start(struct file *file)
  {
  	struct inode *inode = file_inode(file);
  	struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
  	struct btrfs_root *root = BTRFS_I(inode)->root;
  	struct btrfs_trans_handle *trans;
  	struct btrfs_file_private *private;
  	int ret;
  	static bool warned = false;
  
  	ret = -EPERM;
  	if (!capable(CAP_SYS_ADMIN))
  		goto out;
  
  	if (!warned) {
  		btrfs_warn(fs_info,
  			"Userspace transaction mechanism is considered "
  			"deprecated and slated to be removed in 4.17. "
  			"If you have a valid use case please "
  			"speak up on the mailing list");
  		WARN_ON(1);
  		warned = true;
  	}
  
  	ret = -EINPROGRESS;
  	private = file->private_data;
  	if (private && private->trans)
  		goto out;
  	if (!private) {
  		private = kzalloc(sizeof(struct btrfs_file_private),
  				  GFP_KERNEL);
  		if (!private)
  			return -ENOMEM;
  		file->private_data = private;
  	}
  
  	ret = -EROFS;
  	if (btrfs_root_readonly(root))
  		goto out;
  
  	ret = mnt_want_write_file(file);
  	if (ret)
  		goto out;
  
  	atomic_inc(&fs_info->open_ioctl_trans);
  
  	ret = -ENOMEM;
  	trans = btrfs_start_ioctl_transaction(root);
  	if (IS_ERR(trans))
  		goto out_drop;
  
  	private->trans = trans;
  	return 0;
  
  out_drop:
  	atomic_dec(&fs_info->open_ioctl_trans);
  	mnt_drop_write_file(file);
  out:
  	return ret;
  }
  
  static long btrfs_ioctl_default_subvol(struct file *file, void __user *argp)
  {
  	struct inode *inode = file_inode(file);
  	struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
  	struct btrfs_root *root = BTRFS_I(inode)->root;
  	struct btrfs_root *new_root;
  	struct btrfs_dir_item *di;
  	struct btrfs_trans_handle *trans;
  	struct btrfs_path *path;
  	struct btrfs_key location;
  	struct btrfs_disk_key disk_key;
  	u64 objectid = 0;
  	u64 dir_id;
  	int ret;
  
  	if (!capable(CAP_SYS_ADMIN))
  		return -EPERM;
  
  	ret = mnt_want_write_file(file);
  	if (ret)
  		return ret;
  
  	if (copy_from_user(&objectid, argp, sizeof(objectid))) {
  		ret = -EFAULT;
  		goto out;
  	}
  
  	if (!objectid)
  		objectid = BTRFS_FS_TREE_OBJECTID;
  
  	location.objectid = objectid;
  	location.type = BTRFS_ROOT_ITEM_KEY;
  	location.offset = (u64)-1;
  
  	new_root = btrfs_read_fs_root_no_name(fs_info, &location);
  	if (IS_ERR(new_root)) {
  		ret = PTR_ERR(new_root);
  		goto out;
  	}
  	if (!is_fstree(new_root->objectid)) {
  		ret = -ENOENT;
  		goto out;
  	}
  
  	path = btrfs_alloc_path();
  	if (!path) {
  		ret = -ENOMEM;
  		goto out;
  	}
  	path->leave_spinning = 1;
  
  	trans = btrfs_start_transaction(root, 1);
  	if (IS_ERR(trans)) {
  		btrfs_free_path(path);
  		ret = PTR_ERR(trans);
  		goto out;
  	}
  
  	dir_id = btrfs_super_root_dir(fs_info->super_copy);
  	di = btrfs_lookup_dir_item(trans, fs_info->tree_root, path,
  				   dir_id, "default", 7, 1);
  	if (IS_ERR_OR_NULL(di)) {
  		btrfs_free_path(path);
  		btrfs_end_transaction(trans);
  		btrfs_err(fs_info,
  			  "Umm, you don't have the default diritem, this isn't going to work");
  		ret = -ENOENT;
  		goto out;
  	}
  
  	btrfs_cpu_key_to_disk(&disk_key, &new_root->root_key);
  	btrfs_set_dir_item_key(path->nodes[0], di, &disk_key);
  	btrfs_mark_buffer_dirty(path->nodes[0]);
  	btrfs_free_path(path);
  
  	btrfs_set_fs_incompat(fs_info, DEFAULT_SUBVOL);
  	btrfs_end_transaction(trans);
  out:
  	mnt_drop_write_file(file);
  	return ret;
  }
  
  void btrfs_get_block_group_info(struct list_head *groups_list,
  				struct btrfs_ioctl_space_info *space)
  {
  	struct btrfs_block_group_cache *block_group;
  
  	space->total_bytes = 0;
  	space->used_bytes = 0;
  	space->flags = 0;
  	list_for_each_entry(block_group, groups_list, list) {
  		space->flags = block_group->flags;
  		space->total_bytes += block_group->key.offset;
  		space->used_bytes +=
  			btrfs_block_group_used(&block_group->item);
  	}
  }
  
  static long btrfs_ioctl_space_info(struct btrfs_fs_info *fs_info,
  				   void __user *arg)
  {
  	struct btrfs_ioctl_space_args space_args;
  	struct btrfs_ioctl_space_info space;
  	struct btrfs_ioctl_space_info *dest;
  	struct btrfs_ioctl_space_info *dest_orig;
  	struct btrfs_ioctl_space_info __user *user_dest;
  	struct btrfs_space_info *info;
  	u64 types[] = {BTRFS_BLOCK_GROUP_DATA,
  		       BTRFS_BLOCK_GROUP_SYSTEM,
  		       BTRFS_BLOCK_GROUP_METADATA,
  		       BTRFS_BLOCK_GROUP_DATA | BTRFS_BLOCK_GROUP_METADATA};
  	int num_types = 4;
  	int alloc_size;
  	int ret = 0;
  	u64 slot_count = 0;
  	int i, c;
  
  	if (copy_from_user(&space_args,
  			   (struct btrfs_ioctl_space_args __user *)arg,
  			   sizeof(space_args)))
  		return -EFAULT;
  
  	for (i = 0; i < num_types; i++) {
  		struct btrfs_space_info *tmp;
  
  		info = NULL;
  		rcu_read_lock();
  		list_for_each_entry_rcu(tmp, &fs_info->space_info,
  					list) {
  			if (tmp->flags == types[i]) {
  				info = tmp;
  				break;
  			}
  		}
  		rcu_read_unlock();
  
  		if (!info)
  			continue;
  
  		down_read(&info->groups_sem);
  		for (c = 0; c < BTRFS_NR_RAID_TYPES; c++) {
  			if (!list_empty(&info->block_groups[c]))
  				slot_count++;
  		}
  		up_read(&info->groups_sem);
  	}
  
  	/*
  	 * Global block reserve, exported as a space_info
  	 */
  	slot_count++;
  
  	/* space_slots == 0 means they are asking for a count */
  	if (space_args.space_slots == 0) {
  		space_args.total_spaces = slot_count;
  		goto out;
  	}
  
  	slot_count = min_t(u64, space_args.space_slots, slot_count);
  
  	alloc_size = sizeof(*dest) * slot_count;
  
  	/* we generally have at most 6 or so space infos, one for each raid
  	 * level.  So, a whole page should be more than enough for everyone
  	 */
  	if (alloc_size > PAGE_SIZE)
  		return -ENOMEM;
  
  	space_args.total_spaces = 0;
  	dest = kmalloc(alloc_size, GFP_KERNEL);
  	if (!dest)
  		return -ENOMEM;
  	dest_orig = dest;
  
  	/* now we have a buffer to copy into */
  	for (i = 0; i < num_types; i++) {
  		struct btrfs_space_info *tmp;
  
  		if (!slot_count)
  			break;
  
  		info = NULL;
  		rcu_read_lock();
  		list_for_each_entry_rcu(tmp, &fs_info->space_info,
  					list) {
  			if (tmp->flags == types[i]) {
  				info = tmp;
  				break;
  			}
  		}
  		rcu_read_unlock();
  
  		if (!info)
  			continue;
  		down_read(&info->groups_sem);
  		for (c = 0; c < BTRFS_NR_RAID_TYPES; c++) {
  			if (!list_empty(&info->block_groups[c])) {
  				btrfs_get_block_group_info(
  					&info->block_groups[c], &space);
  				memcpy(dest, &space, sizeof(space));
  				dest++;
  				space_args.total_spaces++;
  				slot_count--;
  			}
  			if (!slot_count)
  				break;
  		}
  		up_read(&info->groups_sem);
  	}
  
  	/*
  	 * Add global block reserve
  	 */
  	if (slot_count) {
  		struct btrfs_block_rsv *block_rsv = &fs_info->global_block_rsv;
  
  		spin_lock(&block_rsv->lock);
  		space.total_bytes = block_rsv->size;
  		space.used_bytes = block_rsv->size - block_rsv->reserved;
  		spin_unlock(&block_rsv->lock);
  		space.flags = BTRFS_SPACE_INFO_GLOBAL_RSV;
  		memcpy(dest, &space, sizeof(space));
  		space_args.total_spaces++;
  	}
  
  	user_dest = (struct btrfs_ioctl_space_info __user *)
  		(arg + sizeof(struct btrfs_ioctl_space_args));
  
  	if (copy_to_user(user_dest, dest_orig, alloc_size))
  		ret = -EFAULT;
  
  	kfree(dest_orig);
  out:
  	if (ret == 0 && copy_to_user(arg, &space_args, sizeof(space_args)))
  		ret = -EFAULT;
  
  	return ret;
  }
  
  /*
   * there are many ways the trans_start and trans_end ioctls can lead
   * to deadlocks.  They should only be used by applications that
   * basically own the machine, and have a very in depth understanding
   * of all the possible deadlocks and enospc problems.
   */
  long btrfs_ioctl_trans_end(struct file *file)
  {
  	struct inode *inode = file_inode(file);
  	struct btrfs_root *root = BTRFS_I(inode)->root;
  	struct btrfs_file_private *private = file->private_data;
  
  	if (!private || !private->trans)
  		return -EINVAL;
  
  	btrfs_end_transaction(private->trans);
  	private->trans = NULL;
  
  	atomic_dec(&root->fs_info->open_ioctl_trans);
  
  	mnt_drop_write_file(file);
  	return 0;
  }
  
  static noinline long btrfs_ioctl_start_sync(struct btrfs_root *root,
  					    void __user *argp)
  {
  	struct btrfs_trans_handle *trans;
  	u64 transid;
  	int ret;
  
  	trans = btrfs_attach_transaction_barrier(root);
  	if (IS_ERR(trans)) {
  		if (PTR_ERR(trans) != -ENOENT)
  			return PTR_ERR(trans);
  
  		/* No running transaction, don't bother */
  		transid = root->fs_info->last_trans_committed;
  		goto out;
  	}
  	transid = trans->transid;
  	ret = btrfs_commit_transaction_async(trans, 0);
  	if (ret) {
  		btrfs_end_transaction(trans);
  		return ret;
  	}
  out:
  	if (argp)
  		if (copy_to_user(argp, &transid, sizeof(transid)))
  			return -EFAULT;
  	return 0;
  }
  
  static noinline long btrfs_ioctl_wait_sync(struct btrfs_fs_info *fs_info,
  					   void __user *argp)
  {
  	u64 transid;
  
  	if (argp) {
  		if (copy_from_user(&transid, argp, sizeof(transid)))
  			return -EFAULT;
  	} else {
  		transid = 0;  /* current trans */
  	}
  	return btrfs_wait_for_commit(fs_info, transid);
  }
  
  static long btrfs_ioctl_scrub(struct file *file, void __user *arg)
  {
  	struct btrfs_fs_info *fs_info = btrfs_sb(file_inode(file)->i_sb);
  	struct btrfs_ioctl_scrub_args *sa;
  	int ret;
  
  	if (!capable(CAP_SYS_ADMIN))
  		return -EPERM;
  
  	sa = memdup_user(arg, sizeof(*sa));
  	if (IS_ERR(sa))
  		return PTR_ERR(sa);
  
  	if (!(sa->flags & BTRFS_SCRUB_READONLY)) {
  		ret = mnt_want_write_file(file);
  		if (ret)
  			goto out;
  	}
  
  	ret = btrfs_scrub_dev(fs_info, sa->devid, sa->start, sa->end,
  			      &sa->progress, sa->flags & BTRFS_SCRUB_READONLY,
  			      0);
  
  	if (copy_to_user(arg, sa, sizeof(*sa)))
  		ret = -EFAULT;
  
  	if (!(sa->flags & BTRFS_SCRUB_READONLY))
  		mnt_drop_write_file(file);
  out:
  	kfree(sa);
  	return ret;
  }
  
  static long btrfs_ioctl_scrub_cancel(struct btrfs_fs_info *fs_info)
  {
  	if (!capable(CAP_SYS_ADMIN))
  		return -EPERM;
  
  	return btrfs_scrub_cancel(fs_info);
  }
  
  static long btrfs_ioctl_scrub_progress(struct btrfs_fs_info *fs_info,
  				       void __user *arg)
  {
  	struct btrfs_ioctl_scrub_args *sa;
  	int ret;
  
  	if (!capable(CAP_SYS_ADMIN))
  		return -EPERM;
  
  	sa = memdup_user(arg, sizeof(*sa));
  	if (IS_ERR(sa))
  		return PTR_ERR(sa);
  
  	ret = btrfs_scrub_progress(fs_info, sa->devid, &sa->progress);
  
  	if (copy_to_user(arg, sa, sizeof(*sa)))
  		ret = -EFAULT;
  
  	kfree(sa);
  	return ret;
  }
  
  static long btrfs_ioctl_get_dev_stats(struct btrfs_fs_info *fs_info,
  				      void __user *arg)
  {
  	struct btrfs_ioctl_get_dev_stats *sa;
  	int ret;
  
  	sa = memdup_user(arg, sizeof(*sa));
  	if (IS_ERR(sa))
  		return PTR_ERR(sa);
  
  	if ((sa->flags & BTRFS_DEV_STATS_RESET) && !capable(CAP_SYS_ADMIN)) {
  		kfree(sa);
  		return -EPERM;
  	}
  
  	ret = btrfs_get_dev_stats(fs_info, sa);
  
  	if (copy_to_user(arg, sa, sizeof(*sa)))
  		ret = -EFAULT;
  
  	kfree(sa);
  	return ret;
  }
  
  static long btrfs_ioctl_dev_replace(struct btrfs_fs_info *fs_info,
  				    void __user *arg)
  {
  	struct btrfs_ioctl_dev_replace_args *p;
  	int ret;
  
  	if (!capable(CAP_SYS_ADMIN))
  		return -EPERM;
  
  	p = memdup_user(arg, sizeof(*p));
  	if (IS_ERR(p))
  		return PTR_ERR(p);
  
  	switch (p->cmd) {
  	case BTRFS_IOCTL_DEV_REPLACE_CMD_START:
  		if (sb_rdonly(fs_info->sb)) {
  			ret = -EROFS;
  			goto out;
  		}
  		if (test_and_set_bit(BTRFS_FS_EXCL_OP, &fs_info->flags)) {
  			ret = BTRFS_ERROR_DEV_EXCL_RUN_IN_PROGRESS;
  		} else {
  			ret = btrfs_dev_replace_by_ioctl(fs_info, p);
  			clear_bit(BTRFS_FS_EXCL_OP, &fs_info->flags);
  		}
  		break;
  	case BTRFS_IOCTL_DEV_REPLACE_CMD_STATUS:
  		btrfs_dev_replace_status(fs_info, p);
  		ret = 0;
  		break;
  	case BTRFS_IOCTL_DEV_REPLACE_CMD_CANCEL:
  		ret = btrfs_dev_replace_cancel(fs_info, p);
  		break;
  	default:
  		ret = -EINVAL;
  		break;
  	}
  
  	if (copy_to_user(arg, p, sizeof(*p)))
  		ret = -EFAULT;
  out:
  	kfree(p);
  	return ret;
  }
  
  static long btrfs_ioctl_ino_to_path(struct btrfs_root *root, void __user *arg)
  {
  	int ret = 0;
  	int i;
  	u64 rel_ptr;
  	int size;
  	struct btrfs_ioctl_ino_path_args *ipa = NULL;
  	struct inode_fs_paths *ipath = NULL;
  	struct btrfs_path *path;
  
  	if (!capable(CAP_DAC_READ_SEARCH))
  		return -EPERM;
  
  	path = btrfs_alloc_path();
  	if (!path) {
  		ret = -ENOMEM;
  		goto out;
  	}
  
  	ipa = memdup_user(arg, sizeof(*ipa));
  	if (IS_ERR(ipa)) {
  		ret = PTR_ERR(ipa);
  		ipa = NULL;
  		goto out;
  	}
  
  	size = min_t(u32, ipa->size, 4096);
  	ipath = init_ipath(size, root, path);
  	if (IS_ERR(ipath)) {
  		ret = PTR_ERR(ipath);
  		ipath = NULL;
  		goto out;
  	}
  
  	ret = paths_from_inode(ipa->inum, ipath);
  	if (ret < 0)
  		goto out;
  
  	for (i = 0; i < ipath->fspath->elem_cnt; ++i) {
  		rel_ptr = ipath->fspath->val[i] -
  			  (u64)(unsigned long)ipath->fspath->val;
  		ipath->fspath->val[i] = rel_ptr;
  	}
  
  	ret = copy_to_user((void *)(unsigned long)ipa->fspath,
  			   (void *)(unsigned long)ipath->fspath, size);
  	if (ret) {
  		ret = -EFAULT;
  		goto out;
  	}
  
  out:
  	btrfs_free_path(path);
  	free_ipath(ipath);
  	kfree(ipa);
  
  	return ret;
  }
  
  static int build_ino_list(u64 inum, u64 offset, u64 root, void *ctx)
  {
  	struct btrfs_data_container *inodes = ctx;
  	const size_t c = 3 * sizeof(u64);
  
  	if (inodes->bytes_left >= c) {
  		inodes->bytes_left -= c;
  		inodes->val[inodes->elem_cnt] = inum;
  		inodes->val[inodes->elem_cnt + 1] = offset;
  		inodes->val[inodes->elem_cnt + 2] = root;
  		inodes->elem_cnt += 3;
  	} else {
  		inodes->bytes_missing += c - inodes->bytes_left;
  		inodes->bytes_left = 0;
  		inodes->elem_missed += 3;
  	}
  
  	return 0;
  }
  
  static long btrfs_ioctl_logical_to_ino(struct btrfs_fs_info *fs_info,
  					void __user *arg)
  {
  	int ret = 0;
  	int size;
  	struct btrfs_ioctl_logical_ino_args *loi;
  	struct btrfs_data_container *inodes = NULL;
  	struct btrfs_path *path = NULL;
  
  	if (!capable(CAP_SYS_ADMIN))
  		return -EPERM;
  
  	loi = memdup_user(arg, sizeof(*loi));
  	if (IS_ERR(loi))
  		return PTR_ERR(loi);
  
  	path = btrfs_alloc_path();
  	if (!path) {
  		ret = -ENOMEM;
  		goto out;
  	}
  
  	size = min_t(u32, loi->size, SZ_64K);
  	inodes = init_data_container(size);
  	if (IS_ERR(inodes)) {
  		ret = PTR_ERR(inodes);
  		inodes = NULL;
  		goto out;
  	}
  
  	ret = iterate_inodes_from_logical(loi->logical, fs_info, path,
  					  build_ino_list, inodes);
  	if (ret == -EINVAL)
  		ret = -ENOENT;
  	if (ret < 0)
  		goto out;
  
  	ret = copy_to_user((void *)(unsigned long)loi->inodes,
  			   (void *)(unsigned long)inodes, size);
  	if (ret)
  		ret = -EFAULT;
  
  out:
  	btrfs_free_path(path);
  	kvfree(inodes);
  	kfree(loi);
  
  	return ret;
  }
  
  void update_ioctl_balance_args(struct btrfs_fs_info *fs_info, int lock,
  			       struct btrfs_ioctl_balance_args *bargs)
  {
  	struct btrfs_balance_control *bctl = fs_info->balance_ctl;
  
  	bargs->flags = bctl->flags;
  
  	if (atomic_read(&fs_info->balance_running))
  		bargs->state |= BTRFS_BALANCE_STATE_RUNNING;
  	if (atomic_read(&fs_info->balance_pause_req))
  		bargs->state |= BTRFS_BALANCE_STATE_PAUSE_REQ;
  	if (atomic_read(&fs_info->balance_cancel_req))
  		bargs->state |= BTRFS_BALANCE_STATE_CANCEL_REQ;
  
  	memcpy(&bargs->data, &bctl->data, sizeof(bargs->data));
  	memcpy(&bargs->meta, &bctl->meta, sizeof(bargs->meta));
  	memcpy(&bargs->sys, &bctl->sys, sizeof(bargs->sys));
  
  	if (lock) {
  		spin_lock(&fs_info->balance_lock);
  		memcpy(&bargs->stat, &bctl->stat, sizeof(bargs->stat));
  		spin_unlock(&fs_info->balance_lock);
  	} else {
  		memcpy(&bargs->stat, &bctl->stat, sizeof(bargs->stat));
  	}
  }
  
  static long btrfs_ioctl_balance(struct file *file, void __user *arg)
  {
  	struct btrfs_root *root = BTRFS_I(file_inode(file))->root;
  	struct btrfs_fs_info *fs_info = root->fs_info;
  	struct btrfs_ioctl_balance_args *bargs;
  	struct btrfs_balance_control *bctl;
  	bool need_unlock; /* for mut. excl. ops lock */
  	int ret;
  
  	if (!capable(CAP_SYS_ADMIN))
  		return -EPERM;
  
  	ret = mnt_want_write_file(file);
  	if (ret)
  		return ret;
  
  again:
  	if (!test_and_set_bit(BTRFS_FS_EXCL_OP, &fs_info->flags)) {
  		mutex_lock(&fs_info->volume_mutex);
  		mutex_lock(&fs_info->balance_mutex);
  		need_unlock = true;
  		goto locked;
  	}
  
  	/*
  	 * mut. excl. ops lock is locked.  Three possibilities:
  	 *   (1) some other op is running
  	 *   (2) balance is running
  	 *   (3) balance is paused -- special case (think resume)
  	 */
  	mutex_lock(&fs_info->balance_mutex);
  	if (fs_info->balance_ctl) {
  		/* this is either (2) or (3) */
  		if (!atomic_read(&fs_info->balance_running)) {
  			mutex_unlock(&fs_info->balance_mutex);
  			if (!mutex_trylock(&fs_info->volume_mutex))
  				goto again;
  			mutex_lock(&fs_info->balance_mutex);
  
  			if (fs_info->balance_ctl &&
  			    !atomic_read(&fs_info->balance_running)) {
  				/* this is (3) */
  				need_unlock = false;
  				goto locked;
  			}
  
  			mutex_unlock(&fs_info->balance_mutex);
  			mutex_unlock(&fs_info->volume_mutex);
  			goto again;
  		} else {
  			/* this is (2) */
  			mutex_unlock(&fs_info->balance_mutex);
  			ret = -EINPROGRESS;
  			goto out;
  		}
  	} else {
  		/* this is (1) */
  		mutex_unlock(&fs_info->balance_mutex);
  		ret = BTRFS_ERROR_DEV_EXCL_RUN_IN_PROGRESS;
  		goto out;
  	}
  
  locked:
  	BUG_ON(!test_bit(BTRFS_FS_EXCL_OP, &fs_info->flags));
  
  	if (arg) {
  		bargs = memdup_user(arg, sizeof(*bargs));
  		if (IS_ERR(bargs)) {
  			ret = PTR_ERR(bargs);
  			goto out_unlock;
  		}
  
  		if (bargs->flags & BTRFS_BALANCE_RESUME) {
  			if (!fs_info->balance_ctl) {
  				ret = -ENOTCONN;
  				goto out_bargs;
  			}
  
  			bctl = fs_info->balance_ctl;
  			spin_lock(&fs_info->balance_lock);
  			bctl->flags |= BTRFS_BALANCE_RESUME;
  			spin_unlock(&fs_info->balance_lock);
  
  			goto do_balance;
  		}
  	} else {
  		bargs = NULL;
  	}
  
  	if (fs_info->balance_ctl) {
  		ret = -EINPROGRESS;
  		goto out_bargs;
  	}
  
  	bctl = kzalloc(sizeof(*bctl), GFP_KERNEL);
  	if (!bctl) {
  		ret = -ENOMEM;
  		goto out_bargs;
  	}
  
  	bctl->fs_info = fs_info;
  	if (arg) {
  		memcpy(&bctl->data, &bargs->data, sizeof(bctl->data));
  		memcpy(&bctl->meta, &bargs->meta, sizeof(bctl->meta));
  		memcpy(&bctl->sys, &bargs->sys, sizeof(bctl->sys));
  
  		bctl->flags = bargs->flags;
  	} else {
  		/* balance everything - no filters */
  		bctl->flags |= BTRFS_BALANCE_TYPE_MASK;
  	}
  
  	if (bctl->flags & ~(BTRFS_BALANCE_ARGS_MASK | BTRFS_BALANCE_TYPE_MASK)) {
  		ret = -EINVAL;
  		goto out_bctl;
  	}
  
  do_balance:
  	/*
  	 * Ownership of bctl and filesystem flag BTRFS_FS_EXCL_OP
  	 * goes to to btrfs_balance.  bctl is freed in __cancel_balance,
  	 * or, if restriper was paused all the way until unmount, in
  	 * free_fs_info.  The flag is cleared in __cancel_balance.
  	 */
  	need_unlock = false;
  
  	ret = btrfs_balance(bctl, bargs);
  	bctl = NULL;
  
  	if (arg) {
  		if (copy_to_user(arg, bargs, sizeof(*bargs)))
  			ret = -EFAULT;
  	}
  
  out_bctl:
  	kfree(bctl);
  out_bargs:
  	kfree(bargs);
  out_unlock:
  	mutex_unlock(&fs_info->balance_mutex);
  	mutex_unlock(&fs_info->volume_mutex);
  	if (need_unlock)
  		clear_bit(BTRFS_FS_EXCL_OP, &fs_info->flags);
  out:
  	mnt_drop_write_file(file);
  	return ret;
  }
  
  static long btrfs_ioctl_balance_ctl(struct btrfs_fs_info *fs_info, int cmd)
  {
  	if (!capable(CAP_SYS_ADMIN))
  		return -EPERM;
  
  	switch (cmd) {
  	case BTRFS_BALANCE_CTL_PAUSE:
  		return btrfs_pause_balance(fs_info);
  	case BTRFS_BALANCE_CTL_CANCEL:
  		return btrfs_cancel_balance(fs_info);
  	}
  
  	return -EINVAL;
  }
  
  static long btrfs_ioctl_balance_progress(struct btrfs_fs_info *fs_info,
  					 void __user *arg)
  {
  	struct btrfs_ioctl_balance_args *bargs;
  	int ret = 0;
  
  	if (!capable(CAP_SYS_ADMIN))
  		return -EPERM;
  
  	mutex_lock(&fs_info->balance_mutex);
  	if (!fs_info->balance_ctl) {
  		ret = -ENOTCONN;
  		goto out;
  	}
  
  	bargs = kzalloc(sizeof(*bargs), GFP_KERNEL);
  	if (!bargs) {
  		ret = -ENOMEM;
  		goto out;
  	}
  
  	update_ioctl_balance_args(fs_info, 1, bargs);
  
  	if (copy_to_user(arg, bargs, sizeof(*bargs)))
  		ret = -EFAULT;
  
  	kfree(bargs);
  out:
  	mutex_unlock(&fs_info->balance_mutex);
  	return ret;
  }
  
  static long btrfs_ioctl_quota_ctl(struct file *file, void __user *arg)
  {
  	struct inode *inode = file_inode(file);
  	struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
  	struct btrfs_ioctl_quota_ctl_args *sa;
  	struct btrfs_trans_handle *trans = NULL;
  	int ret;
  	int err;
  
  	if (!capable(CAP_SYS_ADMIN))
  		return -EPERM;
  
  	ret = mnt_want_write_file(file);
  	if (ret)
  		return ret;
  
  	sa = memdup_user(arg, sizeof(*sa));
  	if (IS_ERR(sa)) {
  		ret = PTR_ERR(sa);
  		goto drop_write;
  	}
  
  	down_write(&fs_info->subvol_sem);
  	trans = btrfs_start_transaction(fs_info->tree_root, 2);
  	if (IS_ERR(trans)) {
  		ret = PTR_ERR(trans);
  		goto out;
  	}
  
  	switch (sa->cmd) {
  	case BTRFS_QUOTA_CTL_ENABLE:
  		ret = btrfs_quota_enable(trans, fs_info);
  		break;
  	case BTRFS_QUOTA_CTL_DISABLE:
  		ret = btrfs_quota_disable(trans, fs_info);
  		break;
  	default:
  		ret = -EINVAL;
  		break;
  	}
  
  	err = btrfs_commit_transaction(trans);
  	if (err && !ret)
  		ret = err;
  out:
  	kfree(sa);
  	up_write(&fs_info->subvol_sem);
  drop_write:
  	mnt_drop_write_file(file);
  	return ret;
  }
  
  static long btrfs_ioctl_qgroup_assign(struct file *file, void __user *arg)
  {
  	struct inode *inode = file_inode(file);
  	struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
  	struct btrfs_root *root = BTRFS_I(inode)->root;
  	struct btrfs_ioctl_qgroup_assign_args *sa;
  	struct btrfs_trans_handle *trans;
  	int ret;
  	int err;
  
  	if (!capable(CAP_SYS_ADMIN))
  		return -EPERM;
  
  	ret = mnt_want_write_file(file);
  	if (ret)
  		return ret;
  
  	sa = memdup_user(arg, sizeof(*sa));
  	if (IS_ERR(sa)) {
  		ret = PTR_ERR(sa);
  		goto drop_write;
  	}
  
  	trans = btrfs_join_transaction(root);
  	if (IS_ERR(trans)) {
  		ret = PTR_ERR(trans);
  		goto out;
  	}
  
  	if (sa->assign) {
  		ret = btrfs_add_qgroup_relation(trans, fs_info,
  						sa->src, sa->dst);
  	} else {
  		ret = btrfs_del_qgroup_relation(trans, fs_info,
  						sa->src, sa->dst);
  	}
  
  	/* update qgroup status and info */
  	err = btrfs_run_qgroups(trans, fs_info);
  	if (err < 0)
  		btrfs_handle_fs_error(fs_info, err,
  				      "failed to update qgroup status and info");
  	err = btrfs_end_transaction(trans);
  	if (err && !ret)
  		ret = err;
  
  out:
  	kfree(sa);
  drop_write:
  	mnt_drop_write_file(file);
  	return ret;
  }
  
  static long btrfs_ioctl_qgroup_create(struct file *file, void __user *arg)
  {
  	struct inode *inode = file_inode(file);
  	struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
  	struct btrfs_root *root = BTRFS_I(inode)->root;
  	struct btrfs_ioctl_qgroup_create_args *sa;
  	struct btrfs_trans_handle *trans;
  	int ret;
  	int err;
  
  	if (!capable(CAP_SYS_ADMIN))
  		return -EPERM;
  
  	ret = mnt_want_write_file(file);
  	if (ret)
  		return ret;
  
  	sa = memdup_user(arg, sizeof(*sa));
  	if (IS_ERR(sa)) {
  		ret = PTR_ERR(sa);
  		goto drop_write;
  	}
  
  	if (!sa->qgroupid) {
  		ret = -EINVAL;
  		goto out;
  	}
  
  	trans = btrfs_join_transaction(root);
  	if (IS_ERR(trans)) {
  		ret = PTR_ERR(trans);
  		goto out;
  	}
  
  	if (sa->create) {
  		ret = btrfs_create_qgroup(trans, fs_info, sa->qgroupid);
  	} else {
  		ret = btrfs_remove_qgroup(trans, fs_info, sa->qgroupid);
  	}
  
  	err = btrfs_end_transaction(trans);
  	if (err && !ret)
  		ret = err;
  
  out:
  	kfree(sa);
  drop_write:
  	mnt_drop_write_file(file);
  	return ret;
  }
  
  static long btrfs_ioctl_qgroup_limit(struct file *file, void __user *arg)
  {
  	struct inode *inode = file_inode(file);
  	struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
  	struct btrfs_root *root = BTRFS_I(inode)->root;
  	struct btrfs_ioctl_qgroup_limit_args *sa;
  	struct btrfs_trans_handle *trans;
  	int ret;
  	int err;
  	u64 qgroupid;
  
  	if (!capable(CAP_SYS_ADMIN))
  		return -EPERM;
  
  	ret = mnt_want_write_file(file);
  	if (ret)
  		return ret;
  
  	sa = memdup_user(arg, sizeof(*sa));
  	if (IS_ERR(sa)) {
  		ret = PTR_ERR(sa);
  		goto drop_write;
  	}
  
  	trans = btrfs_join_transaction(root);
  	if (IS_ERR(trans)) {
  		ret = PTR_ERR(trans);
  		goto out;
  	}
  
  	qgroupid = sa->qgroupid;
  	if (!qgroupid) {
  		/* take the current subvol as qgroup */
  		qgroupid = root->root_key.objectid;
  	}
  
  	ret = btrfs_limit_qgroup(trans, fs_info, qgroupid, &sa->lim);
  
  	err = btrfs_end_transaction(trans);
  	if (err && !ret)
  		ret = err;
  
  out:
  	kfree(sa);
  drop_write:
  	mnt_drop_write_file(file);
  	return ret;
  }
  
  static long btrfs_ioctl_quota_rescan(struct file *file, void __user *arg)
  {
  	struct inode *inode = file_inode(file);
  	struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
  	struct btrfs_ioctl_quota_rescan_args *qsa;
  	int ret;
  
  	if (!capable(CAP_SYS_ADMIN))
  		return -EPERM;
  
  	ret = mnt_want_write_file(file);
  	if (ret)
  		return ret;
  
  	qsa = memdup_user(arg, sizeof(*qsa));
  	if (IS_ERR(qsa)) {
  		ret = PTR_ERR(qsa);
  		goto drop_write;
  	}
  
  	if (qsa->flags) {
  		ret = -EINVAL;
  		goto out;
  	}
  
  	ret = btrfs_qgroup_rescan(fs_info);
  
  out:
  	kfree(qsa);
  drop_write:
  	mnt_drop_write_file(file);
  	return ret;
  }
  
  static long btrfs_ioctl_quota_rescan_status(struct file *file, void __user *arg)
  {
  	struct inode *inode = file_inode(file);
  	struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
  	struct btrfs_ioctl_quota_rescan_args *qsa;
  	int ret = 0;
  
  	if (!capable(CAP_SYS_ADMIN))
  		return -EPERM;
  
  	qsa = kzalloc(sizeof(*qsa), GFP_KERNEL);
  	if (!qsa)
  		return -ENOMEM;
  
  	if (fs_info->qgroup_flags & BTRFS_QGROUP_STATUS_FLAG_RESCAN) {
  		qsa->flags = 1;
  		qsa->progress = fs_info->qgroup_rescan_progress.objectid;
  	}
  
  	if (copy_to_user(arg, qsa, sizeof(*qsa)))
  		ret = -EFAULT;
  
  	kfree(qsa);
  	return ret;
  }
  
  static long btrfs_ioctl_quota_rescan_wait(struct file *file, void __user *arg)
  {
  	struct inode *inode = file_inode(file);
  	struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
  
  	if (!capable(CAP_SYS_ADMIN))
  		return -EPERM;
  
  	return btrfs_qgroup_wait_for_completion(fs_info, true);
  }
  
  static long _btrfs_ioctl_set_received_subvol(struct file *file,
  					    struct btrfs_ioctl_received_subvol_args *sa)
  {
  	struct inode *inode = file_inode(file);
  	struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
  	struct btrfs_root *root = BTRFS_I(inode)->root;
  	struct btrfs_root_item *root_item = &root->root_item;
  	struct btrfs_trans_handle *trans;
  	struct timespec ct = current_time(inode);
  	int ret = 0;
  	int received_uuid_changed;
  
  	if (!inode_owner_or_capable(inode))
  		return -EPERM;
  
  	ret = mnt_want_write_file(file);
  	if (ret < 0)
  		return ret;
  
  	down_write(&fs_info->subvol_sem);
  
  	if (btrfs_ino(BTRFS_I(inode)) != BTRFS_FIRST_FREE_OBJECTID) {
  		ret = -EINVAL;
  		goto out;
  	}
  
  	if (btrfs_root_readonly(root)) {
  		ret = -EROFS;
  		goto out;
  	}
  
  	/*
  	 * 1 - root item
  	 * 2 - uuid items (received uuid + subvol uuid)
  	 */
  	trans = btrfs_start_transaction(root, 3);
  	if (IS_ERR(trans)) {
  		ret = PTR_ERR(trans);
  		trans = NULL;
  		goto out;
  	}
  
  	sa->rtransid = trans->transid;
  	sa->rtime.sec = ct.tv_sec;
  	sa->rtime.nsec = ct.tv_nsec;
  
  	received_uuid_changed = memcmp(root_item->received_uuid, sa->uuid,
  				       BTRFS_UUID_SIZE);
  	if (received_uuid_changed &&
  	    !btrfs_is_empty_uuid(root_item->received_uuid))
  		btrfs_uuid_tree_rem(trans, fs_info, root_item->received_uuid,
  				    BTRFS_UUID_KEY_RECEIVED_SUBVOL,
  				    root->root_key.objectid);
  	memcpy(root_item->received_uuid, sa->uuid, BTRFS_UUID_SIZE);
  	btrfs_set_root_stransid(root_item, sa->stransid);
  	btrfs_set_root_rtransid(root_item, sa->rtransid);
  	btrfs_set_stack_timespec_sec(&root_item->stime, sa->stime.sec);
  	btrfs_set_stack_timespec_nsec(&root_item->stime, sa->stime.nsec);
  	btrfs_set_stack_timespec_sec(&root_item->rtime, sa->rtime.sec);
  	btrfs_set_stack_timespec_nsec(&root_item->rtime, sa->rtime.nsec);
  
  	ret = btrfs_update_root(trans, fs_info->tree_root,
  				&root->root_key, &root->root_item);
  	if (ret < 0) {
  		btrfs_end_transaction(trans);
  		goto out;
  	}
  	if (received_uuid_changed && !btrfs_is_empty_uuid(sa->uuid)) {
  		ret = btrfs_uuid_tree_add(trans, fs_info, sa->uuid,
  					  BTRFS_UUID_KEY_RECEIVED_SUBVOL,
  					  root->root_key.objectid);
  		if (ret < 0 && ret != -EEXIST) {
  			btrfs_abort_transaction(trans, ret);
  			goto out;
  		}
  	}
  	ret = btrfs_commit_transaction(trans);
  	if (ret < 0) {
  		btrfs_abort_transaction(trans, ret);
  		goto out;
  	}
  
  out:
  	up_write(&fs_info->subvol_sem);
  	mnt_drop_write_file(file);
  	return ret;
  }
  
  #ifdef CONFIG_64BIT
  static long btrfs_ioctl_set_received_subvol_32(struct file *file,
  						void __user *arg)
  {
  	struct btrfs_ioctl_received_subvol_args_32 *args32 = NULL;
  	struct btrfs_ioctl_received_subvol_args *args64 = NULL;
  	int ret = 0;
  
  	args32 = memdup_user(arg, sizeof(*args32));
  	if (IS_ERR(args32))
  		return PTR_ERR(args32);
  
  	args64 = kmalloc(sizeof(*args64), GFP_KERNEL);
  	if (!args64) {
  		ret = -ENOMEM;
  		goto out;
  	}
  
  	memcpy(args64->uuid, args32->uuid, BTRFS_UUID_SIZE);
  	args64->stransid = args32->stransid;
  	args64->rtransid = args32->rtransid;
  	args64->stime.sec = args32->stime.sec;
  	args64->stime.nsec = args32->stime.nsec;
  	args64->rtime.sec = args32->rtime.sec;
  	args64->rtime.nsec = args32->rtime.nsec;
  	args64->flags = args32->flags;
  
  	ret = _btrfs_ioctl_set_received_subvol(file, args64);
  	if (ret)
  		goto out;
  
  	memcpy(args32->uuid, args64->uuid, BTRFS_UUID_SIZE);
  	args32->stransid = args64->stransid;
  	args32->rtransid = args64->rtransid;
  	args32->stime.sec = args64->stime.sec;
  	args32->stime.nsec = args64->stime.nsec;
  	args32->rtime.sec = args64->rtime.sec;
  	args32->rtime.nsec = args64->rtime.nsec;
  	args32->flags = args64->flags;
  
  	ret = copy_to_user(arg, args32, sizeof(*args32));
  	if (ret)
  		ret = -EFAULT;
  
  out:
  	kfree(args32);
  	kfree(args64);
  	return ret;
  }
  #endif
  
  static long btrfs_ioctl_set_received_subvol(struct file *file,
  					    void __user *arg)
  {
  	struct btrfs_ioctl_received_subvol_args *sa = NULL;
  	int ret = 0;
  
  	sa = memdup_user(arg, sizeof(*sa));
  	if (IS_ERR(sa))
  		return PTR_ERR(sa);
  
  	ret = _btrfs_ioctl_set_received_subvol(file, sa);
  
  	if (ret)
  		goto out;
  
  	ret = copy_to_user(arg, sa, sizeof(*sa));
  	if (ret)
  		ret = -EFAULT;
  
  out:
  	kfree(sa);
  	return ret;
  }
  
  static int btrfs_ioctl_get_fslabel(struct file *file, void __user *arg)
  {
  	struct inode *inode = file_inode(file);
  	struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
  	size_t len;
  	int ret;
  	char label[BTRFS_LABEL_SIZE];
  
  	spin_lock(&fs_info->super_lock);
  	memcpy(label, fs_info->super_copy->label, BTRFS_LABEL_SIZE);
  	spin_unlock(&fs_info->super_lock);
  
  	len = strnlen(label, BTRFS_LABEL_SIZE);
  
  	if (len == BTRFS_LABEL_SIZE) {
  		btrfs_warn(fs_info,
  			   "label is too long, return the first %zu bytes",
  			   --len);
  	}
  
  	ret = copy_to_user(arg, label, len);
  
  	return ret ? -EFAULT : 0;
  }
  
  static int btrfs_ioctl_set_fslabel(struct file *file, void __user *arg)
  {
  	struct inode *inode = file_inode(file);
  	struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
  	struct btrfs_root *root = BTRFS_I(inode)->root;
  	struct btrfs_super_block *super_block = fs_info->super_copy;
  	struct btrfs_trans_handle *trans;
  	char label[BTRFS_LABEL_SIZE];
  	int ret;
  
  	if (!capable(CAP_SYS_ADMIN))
  		return -EPERM;
  
  	if (copy_from_user(label, arg, sizeof(label)))
  		return -EFAULT;
  
  	if (strnlen(label, BTRFS_LABEL_SIZE) == BTRFS_LABEL_SIZE) {
  		btrfs_err(fs_info,
  			  "unable to set label with more than %d bytes",
  			  BTRFS_LABEL_SIZE - 1);
  		return -EINVAL;
  	}
  
  	ret = mnt_want_write_file(file);
  	if (ret)
  		return ret;
  
  	trans = btrfs_start_transaction(root, 0);
  	if (IS_ERR(trans)) {
  		ret = PTR_ERR(trans);
  		goto out_unlock;
  	}
  
  	spin_lock(&fs_info->super_lock);
  	strcpy(super_block->label, label);
  	spin_unlock(&fs_info->super_lock);
  	ret = btrfs_commit_transaction(trans);
  
  out_unlock:
  	mnt_drop_write_file(file);
  	return ret;
  }
  
  #define INIT_FEATURE_FLAGS(suffix) \
  	{ .compat_flags = BTRFS_FEATURE_COMPAT_##suffix, \
  	  .compat_ro_flags = BTRFS_FEATURE_COMPAT_RO_##suffix, \
  	  .incompat_flags = BTRFS_FEATURE_INCOMPAT_##suffix }
  
  int btrfs_ioctl_get_supported_features(void __user *arg)
  {
  	static const struct btrfs_ioctl_feature_flags features[3] = {
  		INIT_FEATURE_FLAGS(SUPP),
  		INIT_FEATURE_FLAGS(SAFE_SET),
  		INIT_FEATURE_FLAGS(SAFE_CLEAR)
  	};
  
  	if (copy_to_user(arg, &features, sizeof(features)))
  		return -EFAULT;
  
  	return 0;
  }
  
  static int btrfs_ioctl_get_features(struct file *file, void __user *arg)
  {
  	struct inode *inode = file_inode(file);
  	struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
  	struct btrfs_super_block *super_block = fs_info->super_copy;
  	struct btrfs_ioctl_feature_flags features;
  
  	features.compat_flags = btrfs_super_compat_flags(super_block);
  	features.compat_ro_flags = btrfs_super_compat_ro_flags(super_block);
  	features.incompat_flags = btrfs_super_incompat_flags(super_block);
  
  	if (copy_to_user(arg, &features, sizeof(features)))
  		return -EFAULT;
  
  	return 0;
  }
  
  static int check_feature_bits(struct btrfs_fs_info *fs_info,
  			      enum btrfs_feature_set set,
  			      u64 change_mask, u64 flags, u64 supported_flags,
  			      u64 safe_set, u64 safe_clear)
  {
  	const char *type = btrfs_feature_set_names[set];
  	char *names;
  	u64 disallowed, unsupported;
  	u64 set_mask = flags & change_mask;
  	u64 clear_mask = ~flags & change_mask;
  
  	unsupported = set_mask & ~supported_flags;
  	if (unsupported) {
  		names = btrfs_printable_features(set, unsupported);
  		if (names) {
  			btrfs_warn(fs_info,
  				   "this kernel does not support the %s feature bit%s",
  				   names, strchr(names, ',') ? "s" : "");
  			kfree(names);
  		} else
  			btrfs_warn(fs_info,
  				   "this kernel does not support %s bits 0x%llx",
  				   type, unsupported);
  		return -EOPNOTSUPP;
  	}
  
  	disallowed = set_mask & ~safe_set;
  	if (disallowed) {
  		names = btrfs_printable_features(set, disallowed);
  		if (names) {
  			btrfs_warn(fs_info,
  				   "can't set the %s feature bit%s while mounted",
  				   names, strchr(names, ',') ? "s" : "");
  			kfree(names);
  		} else
  			btrfs_warn(fs_info,
  				   "can't set %s bits 0x%llx while mounted",
  				   type, disallowed);
  		return -EPERM;
  	}
  
  	disallowed = clear_mask & ~safe_clear;
  	if (disallowed) {
  		names = btrfs_printable_features(set, disallowed);
  		if (names) {
  			btrfs_warn(fs_info,
  				   "can't clear the %s feature bit%s while mounted",
  				   names, strchr(names, ',') ? "s" : "");
  			kfree(names);
  		} else
  			btrfs_warn(fs_info,
  				   "can't clear %s bits 0x%llx while mounted",
  				   type, disallowed);
  		return -EPERM;
  	}
  
  	return 0;
  }
  
  #define check_feature(fs_info, change_mask, flags, mask_base)	\
  check_feature_bits(fs_info, FEAT_##mask_base, change_mask, flags,	\
  		   BTRFS_FEATURE_ ## mask_base ## _SUPP,	\
  		   BTRFS_FEATURE_ ## mask_base ## _SAFE_SET,	\
  		   BTRFS_FEATURE_ ## mask_base ## _SAFE_CLEAR)
  
  static int btrfs_ioctl_set_features(struct file *file, void __user *arg)
  {
  	struct inode *inode = file_inode(file);
  	struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
  	struct btrfs_root *root = BTRFS_I(inode)->root;
  	struct btrfs_super_block *super_block = fs_info->super_copy;
  	struct btrfs_ioctl_feature_flags flags[2];
  	struct btrfs_trans_handle *trans;
  	u64 newflags;
  	int ret;
  
  	if (!capable(CAP_SYS_ADMIN))
  		return -EPERM;
  
  	if (copy_from_user(flags, arg, sizeof(flags)))
  		return -EFAULT;
  
  	/* Nothing to do */
  	if (!flags[0].compat_flags && !flags[0].compat_ro_flags &&
  	    !flags[0].incompat_flags)
  		return 0;
  
  	ret = check_feature(fs_info, flags[0].compat_flags,
  			    flags[1].compat_flags, COMPAT);
  	if (ret)
  		return ret;
  
  	ret = check_feature(fs_info, flags[0].compat_ro_flags,
  			    flags[1].compat_ro_flags, COMPAT_RO);
  	if (ret)
  		return ret;
  
  	ret = check_feature(fs_info, flags[0].incompat_flags,
  			    flags[1].incompat_flags, INCOMPAT);
  	if (ret)
  		return ret;
  
  	ret = mnt_want_write_file(file);
  	if (ret)
  		return ret;
  
  	trans = btrfs_start_transaction(root, 0);
  	if (IS_ERR(trans)) {
  		ret = PTR_ERR(trans);
  		goto out_drop_write;
  	}
  
  	spin_lock(&fs_info->super_lock);
  	newflags = btrfs_super_compat_flags(super_block);
  	newflags |= flags[0].compat_flags & flags[1].compat_flags;
  	newflags &= ~(flags[0].compat_flags & ~flags[1].compat_flags);
  	btrfs_set_super_compat_flags(super_block, newflags);
  
  	newflags = btrfs_super_compat_ro_flags(super_block);
  	newflags |= flags[0].compat_ro_flags & flags[1].compat_ro_flags;
  	newflags &= ~(flags[0].compat_ro_flags & ~flags[1].compat_ro_flags);
  	btrfs_set_super_compat_ro_flags(super_block, newflags);
  
  	newflags = btrfs_super_incompat_flags(super_block);
  	newflags |= flags[0].incompat_flags & flags[1].incompat_flags;
  	newflags &= ~(flags[0].incompat_flags & ~flags[1].incompat_flags);
  	btrfs_set_super_incompat_flags(super_block, newflags);
  	spin_unlock(&fs_info->super_lock);
  
  	ret = btrfs_commit_transaction(trans);
  out_drop_write:
  	mnt_drop_write_file(file);
  
  	return ret;
  }
  
  long btrfs_ioctl(struct file *file, unsigned int
  		cmd, unsigned long arg)
  {
  	struct inode *inode = file_inode(file);
  	struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
  	struct btrfs_root *root = BTRFS_I(inode)->root;
  	void __user *argp = (void __user *)arg;
  
  	switch (cmd) {
  	case FS_IOC_GETFLAGS:
  		return btrfs_ioctl_getflags(file, argp);
  	case FS_IOC_SETFLAGS:
  		return btrfs_ioctl_setflags(file, argp);
  	case FS_IOC_GETVERSION:
  		return btrfs_ioctl_getversion(file, argp);
  	case FITRIM:
  		return btrfs_ioctl_fitrim(file, argp);
  	case BTRFS_IOC_SNAP_CREATE:
  		return btrfs_ioctl_snap_create(file, argp, 0);
  	case BTRFS_IOC_SNAP_CREATE_V2:
  		return btrfs_ioctl_snap_create_v2(file, argp, 0);
  	case BTRFS_IOC_SUBVOL_CREATE:
  		return btrfs_ioctl_snap_create(file, argp, 1);
  	case BTRFS_IOC_SUBVOL_CREATE_V2:
  		return btrfs_ioctl_snap_create_v2(file, argp, 1);
  	case BTRFS_IOC_SNAP_DESTROY:
  		return btrfs_ioctl_snap_destroy(file, argp);
  	case BTRFS_IOC_SUBVOL_GETFLAGS:
  		return btrfs_ioctl_subvol_getflags(file, argp);
  	case BTRFS_IOC_SUBVOL_SETFLAGS:
  		return btrfs_ioctl_subvol_setflags(file, argp);
  	case BTRFS_IOC_DEFAULT_SUBVOL:
  		return btrfs_ioctl_default_subvol(file, argp);
  	case BTRFS_IOC_DEFRAG:
  		return btrfs_ioctl_defrag(file, NULL);
  	case BTRFS_IOC_DEFRAG_RANGE:
  		return btrfs_ioctl_defrag(file, argp);
  	case BTRFS_IOC_RESIZE:
  		return btrfs_ioctl_resize(file, argp);
  	case BTRFS_IOC_ADD_DEV:
  		return btrfs_ioctl_add_dev(fs_info, argp);
  	case BTRFS_IOC_RM_DEV:
  		return btrfs_ioctl_rm_dev(file, argp);
  	case BTRFS_IOC_RM_DEV_V2:
  		return btrfs_ioctl_rm_dev_v2(file, argp);
  	case BTRFS_IOC_FS_INFO:
  		return btrfs_ioctl_fs_info(fs_info, argp);
  	case BTRFS_IOC_DEV_INFO:
  		return btrfs_ioctl_dev_info(fs_info, argp);
  	case BTRFS_IOC_BALANCE:
  		return btrfs_ioctl_balance(file, NULL);
  	case BTRFS_IOC_TRANS_START:
  		return btrfs_ioctl_trans_start(file);
  	case BTRFS_IOC_TRANS_END:
  		return btrfs_ioctl_trans_end(file);
  	case BTRFS_IOC_TREE_SEARCH:
  		return btrfs_ioctl_tree_search(file, argp);
  	case BTRFS_IOC_TREE_SEARCH_V2:
  		return btrfs_ioctl_tree_search_v2(file, argp);
  	case BTRFS_IOC_INO_LOOKUP:
  		return btrfs_ioctl_ino_lookup(file, argp);
  	case BTRFS_IOC_INO_PATHS:
  		return btrfs_ioctl_ino_to_path(root, argp);
  	case BTRFS_IOC_LOGICAL_INO:
  		return btrfs_ioctl_logical_to_ino(fs_info, argp);
  	case BTRFS_IOC_SPACE_INFO:
  		return btrfs_ioctl_space_info(fs_info, argp);
  	case BTRFS_IOC_SYNC: {
  		int ret;
  
  		ret = btrfs_start_delalloc_roots(fs_info, 0, -1);
  		if (ret)
  			return ret;
  		ret = btrfs_sync_fs(inode->i_sb, 1);
  		/*
  		 * The transaction thread may want to do more work,
  		 * namely it pokes the cleaner kthread that will start
  		 * processing uncleaned subvols.
  		 */
  		wake_up_process(fs_info->transaction_kthread);
  		return ret;
  	}
  	case BTRFS_IOC_START_SYNC:
  		return btrfs_ioctl_start_sync(root, argp);
  	case BTRFS_IOC_WAIT_SYNC:
  		return btrfs_ioctl_wait_sync(fs_info, argp);
  	case BTRFS_IOC_SCRUB:
  		return btrfs_ioctl_scrub(file, argp);
  	case BTRFS_IOC_SCRUB_CANCEL:
  		return btrfs_ioctl_scrub_cancel(fs_info);
  	case BTRFS_IOC_SCRUB_PROGRESS:
  		return btrfs_ioctl_scrub_progress(fs_info, argp);
  	case BTRFS_IOC_BALANCE_V2:
  		return btrfs_ioctl_balance(file, argp);
  	case BTRFS_IOC_BALANCE_CTL:
  		return btrfs_ioctl_balance_ctl(fs_info, arg);
  	case BTRFS_IOC_BALANCE_PROGRESS:
  		return btrfs_ioctl_balance_progress(fs_info, argp);
  	case BTRFS_IOC_SET_RECEIVED_SUBVOL:
  		return btrfs_ioctl_set_received_subvol(file, argp);
  #ifdef CONFIG_64BIT
  	case BTRFS_IOC_SET_RECEIVED_SUBVOL_32:
  		return btrfs_ioctl_set_received_subvol_32(file, argp);
  #endif
  	case BTRFS_IOC_SEND:
  		return btrfs_ioctl_send(file, argp);
  	case BTRFS_IOC_GET_DEV_STATS:
  		return btrfs_ioctl_get_dev_stats(fs_info, argp);
  	case BTRFS_IOC_QUOTA_CTL:
  		return btrfs_ioctl_quota_ctl(file, argp);
  	case BTRFS_IOC_QGROUP_ASSIGN:
  		return btrfs_ioctl_qgroup_assign(file, argp);
  	case BTRFS_IOC_QGROUP_CREATE:
  		return btrfs_ioctl_qgroup_create(file, argp);
  	case BTRFS_IOC_QGROUP_LIMIT:
  		return btrfs_ioctl_qgroup_limit(file, argp);
  	case BTRFS_IOC_QUOTA_RESCAN:
  		return btrfs_ioctl_quota_rescan(file, argp);
  	case BTRFS_IOC_QUOTA_RESCAN_STATUS:
  		return btrfs_ioctl_quota_rescan_status(file, argp);
  	case BTRFS_IOC_QUOTA_RESCAN_WAIT:
  		return btrfs_ioctl_quota_rescan_wait(file, argp);
  	case BTRFS_IOC_DEV_REPLACE:
  		return btrfs_ioctl_dev_replace(fs_info, argp);
  	case BTRFS_IOC_GET_FSLABEL:
  		return btrfs_ioctl_get_fslabel(file, argp);
  	case BTRFS_IOC_SET_FSLABEL:
  		return btrfs_ioctl_set_fslabel(file, argp);
  	case BTRFS_IOC_GET_SUPPORTED_FEATURES:
  		return btrfs_ioctl_get_supported_features(argp);
  	case BTRFS_IOC_GET_FEATURES:
  		return btrfs_ioctl_get_features(file, argp);
  	case BTRFS_IOC_SET_FEATURES:
  		return btrfs_ioctl_set_features(file, argp);
  	}
  
  	return -ENOTTY;
  }
  
  #ifdef CONFIG_COMPAT
  long btrfs_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
  {
  	/*
  	 * These all access 32-bit values anyway so no further
  	 * handling is necessary.
  	 */
  	switch (cmd) {
  	case FS_IOC32_GETFLAGS:
  		cmd = FS_IOC_GETFLAGS;
  		break;
  	case FS_IOC32_SETFLAGS:
  		cmd = FS_IOC_SETFLAGS;
  		break;
  	case FS_IOC32_GETVERSION:
  		cmd = FS_IOC_GETVERSION;
  		break;
  	}
  
  	return btrfs_ioctl(file, cmd, (unsigned long) compat_ptr(arg));
  }
  #endif
  