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/blkdev.h>
  #include <linux/module.h>
  #include <linux/buffer_head.h>
  #include <linux/fs.h>
  #include <linux/pagemap.h>
  #include <linux/highmem.h>
  #include <linux/time.h>
  #include <linux/init.h>
  #include <linux/seq_file.h>
  #include <linux/string.h>
  #include <linux/backing-dev.h>
  #include <linux/mount.h>
  #include <linux/mpage.h>
  #include <linux/swap.h>
  #include <linux/writeback.h>
  #include <linux/statfs.h>
  #include <linux/compat.h>
  #include <linux/parser.h>
  #include <linux/ctype.h>
  #include <linux/namei.h>
  #include <linux/miscdevice.h>
  #include <linux/magic.h>
  #include <linux/slab.h>
  #include <linux/cleancache.h>
  #include <linux/ratelimit.h>
  #include <linux/btrfs.h>
  #include "delayed-inode.h"
  #include "ctree.h"
  #include "disk-io.h"
  #include "transaction.h"
  #include "btrfs_inode.h"
  #include "print-tree.h"
  #include "hash.h"
  #include "props.h"
  #include "xattr.h"
  #include "volumes.h"
  #include "export.h"
  #include "compression.h"
  #include "rcu-string.h"
  #include "dev-replace.h"
  #include "free-space-cache.h"
  #include "backref.h"
  #include "tests/btrfs-tests.h"
  
  #include "qgroup.h"
  #define CREATE_TRACE_POINTS
  #include <trace/events/btrfs.h>
  
  static const struct super_operations btrfs_super_ops;
  static struct file_system_type btrfs_fs_type;
  
  static int btrfs_remount(struct super_block *sb, int *flags, char *data);
  
  static const char *btrfs_decode_error(int errno)
  {
  	char *errstr = "unknown";
  
  	switch (errno) {
  	case -EIO:
  		errstr = "IO failure";
  		break;
  	case -ENOMEM:
  		errstr = "Out of memory";
  		break;
  	case -EROFS:
  		errstr = "Readonly filesystem";
  		break;
  	case -EEXIST:
  		errstr = "Object already exists";
  		break;
  	case -ENOSPC:
  		errstr = "No space left";
  		break;
  	case -ENOENT:
  		errstr = "No such entry";
  		break;
  	}
  
  	return errstr;
  }
  
  static void save_error_info(struct btrfs_fs_info *fs_info)
  {
  	/*
  	 * today we only save the error info into ram.  Long term we'll
  	 * also send it down to the disk
  	 */
  	set_bit(BTRFS_FS_STATE_ERROR, &fs_info->fs_state);
  }
  
  /* btrfs handle error by forcing the filesystem readonly */
  static void btrfs_handle_error(struct btrfs_fs_info *fs_info)
  {
  	struct super_block *sb = fs_info->sb;
  
  	if (sb->s_flags & MS_RDONLY)
  		return;
  
  	if (test_bit(BTRFS_FS_STATE_ERROR, &fs_info->fs_state)) {
  		sb->s_flags |= MS_RDONLY;
  		btrfs_info(fs_info, "forced readonly");
  		/*
  		 * Note that a running device replace operation is not
  		 * canceled here although there is no way to update
  		 * the progress. It would add the risk of a deadlock,
  		 * therefore the canceling is ommited. The only penalty
  		 * is that some I/O remains active until the procedure
  		 * completes. The next time when the filesystem is
  		 * mounted writeable again, the device replace
  		 * operation continues.
  		 */
  	}
  }
  
  #ifdef CONFIG_PRINTK
  /*
   * __btrfs_std_error decodes expected errors from the caller and
   * invokes the approciate error response.
   */
  __cold
  void __btrfs_std_error(struct btrfs_fs_info *fs_info, const char *function,
  		       unsigned int line, int errno, const char *fmt, ...)
  {
  	struct super_block *sb = fs_info->sb;
  	const char *errstr;
  
  	/*
  	 * Special case: if the error is EROFS, and we're already
  	 * under MS_RDONLY, then it is safe here.
  	 */
  	if (errno == -EROFS && (sb->s_flags & MS_RDONLY))
    		return;
  
  	errstr = btrfs_decode_error(errno);
  	if (fmt) {
  		struct va_format vaf;
  		va_list args;
  
  		va_start(args, fmt);
  		vaf.fmt = fmt;
  		vaf.va = &args;
  
  		printk(KERN_CRIT
  			"BTRFS: error (device %s) in %s:%d: errno=%d %s (%pV)\n",
  			sb->s_id, function, line, errno, errstr, &vaf);
  		va_end(args);
  	} else {
  		printk(KERN_CRIT "BTRFS: error (device %s) in %s:%d: errno=%d %s\n",
  			sb->s_id, function, line, errno, errstr);
  	}
  
  	/* Don't go through full error handling during mount */
  	save_error_info(fs_info);
  	if (sb->s_flags & MS_BORN)
  		btrfs_handle_error(fs_info);
  }
  
  static const char * const logtypes[] = {
  	"emergency",
  	"alert",
  	"critical",
  	"error",
  	"warning",
  	"notice",
  	"info",
  	"debug",
  };
  
  void btrfs_printk(const struct btrfs_fs_info *fs_info, const char *fmt, ...)
  {
  	struct super_block *sb = fs_info->sb;
  	char lvl[4];
  	struct va_format vaf;
  	va_list args;
  	const char *type = logtypes[4];
  	int kern_level;
  
  	va_start(args, fmt);
  
  	kern_level = printk_get_level(fmt);
  	if (kern_level) {
  		size_t size = printk_skip_level(fmt) - fmt;
  		memcpy(lvl, fmt,  size);
  		lvl[size] = '\0';
  		fmt += size;
  		type = logtypes[kern_level - '0'];
  	} else
  		*lvl = '\0';
  
  	vaf.fmt = fmt;
  	vaf.va = &args;
  
  	printk("%sBTRFS %s (device %s): %pV\n", lvl, type, sb->s_id, &vaf);
  
  	va_end(args);
  }
  
  #else
  
  void __btrfs_std_error(struct btrfs_fs_info *fs_info, const char *function,
  		       unsigned int line, int errno, const char *fmt, ...)
  {
  	struct super_block *sb = fs_info->sb;
  
  	/*
  	 * Special case: if the error is EROFS, and we're already
  	 * under MS_RDONLY, then it is safe here.
  	 */
  	if (errno == -EROFS && (sb->s_flags & MS_RDONLY))
  		return;
  
  	/* Don't go through full error handling during mount */
  	if (sb->s_flags & MS_BORN) {
  		save_error_info(fs_info);
  		btrfs_handle_error(fs_info);
  	}
  }
  #endif
  
  /*
   * We only mark the transaction aborted and then set the file system read-only.
   * This will prevent new transactions from starting or trying to join this
   * one.
   *
   * This means that error recovery at the call site is limited to freeing
   * any local memory allocations and passing the error code up without
   * further cleanup. The transaction should complete as it normally would
   * in the call path but will return -EIO.
   *
   * We'll complete the cleanup in btrfs_end_transaction and
   * btrfs_commit_transaction.
   */
  __cold
  void __btrfs_abort_transaction(struct btrfs_trans_handle *trans,
  			       struct btrfs_root *root, const char *function,
  			       unsigned int line, int errno)
  {
  	trans->aborted = errno;
  	/* Nothing used. The other threads that have joined this
  	 * transaction may be able to continue. */
  	if (!trans->blocks_used && list_empty(&trans->new_bgs)) {
  		const char *errstr;
  
  		errstr = btrfs_decode_error(errno);
  		btrfs_warn(root->fs_info,
  		           "%s:%d: Aborting unused transaction(%s).",
  		           function, line, errstr);
  		return;
  	}
  	ACCESS_ONCE(trans->transaction->aborted) = errno;
  	/* Wake up anybody who may be waiting on this transaction */
  	wake_up(&root->fs_info->transaction_wait);
  	wake_up(&root->fs_info->transaction_blocked_wait);
  	__btrfs_std_error(root->fs_info, function, line, errno, NULL);
  }
  /*
   * __btrfs_panic decodes unexpected, fatal errors from the caller,
   * issues an alert, and either panics or BUGs, depending on mount options.
   */
  __cold
  void __btrfs_panic(struct btrfs_fs_info *fs_info, const char *function,
  		   unsigned int line, int errno, const char *fmt, ...)
  {
  	char *s_id = "<unknown>";
  	const char *errstr;
  	struct va_format vaf = { .fmt = fmt };
  	va_list args;
  
  	if (fs_info)
  		s_id = fs_info->sb->s_id;
  
  	va_start(args, fmt);
  	vaf.va = &args;
  
  	errstr = btrfs_decode_error(errno);
  	if (fs_info && (fs_info->mount_opt & BTRFS_MOUNT_PANIC_ON_FATAL_ERROR))
  		panic(KERN_CRIT "BTRFS panic (device %s) in %s:%d: %pV (errno=%d %s)\n",
  			s_id, function, line, &vaf, errno, errstr);
  
  	btrfs_crit(fs_info, "panic in %s:%d: %pV (errno=%d %s)",
  		   function, line, &vaf, errno, errstr);
  	va_end(args);
  	/* Caller calls BUG() */
  }
  
  static void btrfs_put_super(struct super_block *sb)
  {
  	close_ctree(btrfs_sb(sb)->tree_root);
  }
  
  enum {
  	Opt_degraded, Opt_subvol, Opt_subvolid, Opt_device, Opt_nodatasum,
  	Opt_nodatacow, Opt_max_inline, Opt_alloc_start, Opt_nobarrier, Opt_ssd,
  	Opt_nossd, Opt_ssd_spread, Opt_thread_pool, Opt_noacl, Opt_compress,
  	Opt_compress_type, Opt_compress_force, Opt_compress_force_type,
  	Opt_notreelog, Opt_ratio, Opt_flushoncommit, Opt_discard,
  	Opt_space_cache, Opt_clear_cache, Opt_user_subvol_rm_allowed,
  	Opt_enospc_debug, Opt_subvolrootid, Opt_defrag, Opt_inode_cache,
  	Opt_no_space_cache, Opt_recovery, Opt_skip_balance,
  	Opt_check_integrity, Opt_check_integrity_including_extent_data,
  	Opt_check_integrity_print_mask, Opt_fatal_errors, Opt_rescan_uuid_tree,
  	Opt_commit_interval, Opt_barrier, Opt_nodefrag, Opt_nodiscard,
  	Opt_noenospc_debug, Opt_noflushoncommit, Opt_acl, Opt_datacow,
  	Opt_datasum, Opt_treelog, Opt_noinode_cache,
  	Opt_err,
  };
  
  static match_table_t tokens = {
  	{Opt_degraded, "degraded"},
  	{Opt_subvol, "subvol=%s"},
  	{Opt_subvolid, "subvolid=%s"},
  	{Opt_device, "device=%s"},
  	{Opt_nodatasum, "nodatasum"},
  	{Opt_datasum, "datasum"},
  	{Opt_nodatacow, "nodatacow"},
  	{Opt_datacow, "datacow"},
  	{Opt_nobarrier, "nobarrier"},
  	{Opt_barrier, "barrier"},
  	{Opt_max_inline, "max_inline=%s"},
  	{Opt_alloc_start, "alloc_start=%s"},
  	{Opt_thread_pool, "thread_pool=%d"},
  	{Opt_compress, "compress"},
  	{Opt_compress_type, "compress=%s"},
  	{Opt_compress_force, "compress-force"},
  	{Opt_compress_force_type, "compress-force=%s"},
  	{Opt_ssd, "ssd"},
  	{Opt_ssd_spread, "ssd_spread"},
  	{Opt_nossd, "nossd"},
  	{Opt_acl, "acl"},
  	{Opt_noacl, "noacl"},
  	{Opt_notreelog, "notreelog"},
  	{Opt_treelog, "treelog"},
  	{Opt_flushoncommit, "flushoncommit"},
  	{Opt_noflushoncommit, "noflushoncommit"},
  	{Opt_ratio, "metadata_ratio=%d"},
  	{Opt_discard, "discard"},
  	{Opt_nodiscard, "nodiscard"},
  	{Opt_space_cache, "space_cache"},
  	{Opt_clear_cache, "clear_cache"},
  	{Opt_user_subvol_rm_allowed, "user_subvol_rm_allowed"},
  	{Opt_enospc_debug, "enospc_debug"},
  	{Opt_noenospc_debug, "noenospc_debug"},
  	{Opt_subvolrootid, "subvolrootid=%d"},
  	{Opt_defrag, "autodefrag"},
  	{Opt_nodefrag, "noautodefrag"},
  	{Opt_inode_cache, "inode_cache"},
  	{Opt_noinode_cache, "noinode_cache"},
  	{Opt_no_space_cache, "nospace_cache"},
  	{Opt_recovery, "recovery"},
  	{Opt_skip_balance, "skip_balance"},
  	{Opt_check_integrity, "check_int"},
  	{Opt_check_integrity_including_extent_data, "check_int_data"},
  	{Opt_check_integrity_print_mask, "check_int_print_mask=%d"},
  	{Opt_rescan_uuid_tree, "rescan_uuid_tree"},
  	{Opt_fatal_errors, "fatal_errors=%s"},
  	{Opt_commit_interval, "commit=%d"},
  	{Opt_err, NULL},
  };
  
  /*
   * Regular mount options parser.  Everything that is needed only when
   * reading in a new superblock is parsed here.
   * XXX JDM: This needs to be cleaned up for remount.
   */
  int btrfs_parse_options(struct btrfs_root *root, char *options)
  {
  	struct btrfs_fs_info *info = root->fs_info;
  	substring_t args[MAX_OPT_ARGS];
  	char *p, *num, *orig = NULL;
  	u64 cache_gen;
  	int intarg;
  	int ret = 0;
  	char *compress_type;
  	bool compress_force = false;
  
  	cache_gen = btrfs_super_cache_generation(root->fs_info->super_copy);
  	if (cache_gen)
  		btrfs_set_opt(info->mount_opt, SPACE_CACHE);
  
  	if (!options)
  		goto out;
  
  	/*
  	 * strsep changes the string, duplicate it because parse_options
  	 * gets called twice
  	 */
  	options = kstrdup(options, GFP_NOFS);
  	if (!options)
  		return -ENOMEM;
  
  	orig = options;
  
  	while ((p = strsep(&options, ",")) != NULL) {
  		int token;
  		if (!*p)
  			continue;
  
  		token = match_token(p, tokens, args);
  		switch (token) {
  		case Opt_degraded:
  			btrfs_info(root->fs_info, "allowing degraded mounts");
  			btrfs_set_opt(info->mount_opt, DEGRADED);
  			break;
  		case Opt_subvol:
  		case Opt_subvolid:
  		case Opt_subvolrootid:
  		case Opt_device:
  			/*
  			 * These are parsed by btrfs_parse_early_options
  			 * and can be happily ignored here.
  			 */
  			break;
  		case Opt_nodatasum:
  			btrfs_set_and_info(root, NODATASUM,
  					   "setting nodatasum");
  			break;
  		case Opt_datasum:
  			if (btrfs_test_opt(root, NODATASUM)) {
  				if (btrfs_test_opt(root, NODATACOW))
  					btrfs_info(root->fs_info, "setting datasum, datacow enabled");
  				else
  					btrfs_info(root->fs_info, "setting datasum");
  			}
  			btrfs_clear_opt(info->mount_opt, NODATACOW);
  			btrfs_clear_opt(info->mount_opt, NODATASUM);
  			break;
  		case Opt_nodatacow:
  			if (!btrfs_test_opt(root, NODATACOW)) {
  				if (!btrfs_test_opt(root, COMPRESS) ||
  				    !btrfs_test_opt(root, FORCE_COMPRESS)) {
  					btrfs_info(root->fs_info,
  						   "setting nodatacow, compression disabled");
  				} else {
  					btrfs_info(root->fs_info, "setting nodatacow");
  				}
  			}
  			btrfs_clear_opt(info->mount_opt, COMPRESS);
  			btrfs_clear_opt(info->mount_opt, FORCE_COMPRESS);
  			btrfs_set_opt(info->mount_opt, NODATACOW);
  			btrfs_set_opt(info->mount_opt, NODATASUM);
  			break;
  		case Opt_datacow:
  			btrfs_clear_and_info(root, NODATACOW,
  					     "setting datacow");
  			break;
  		case Opt_compress_force:
  		case Opt_compress_force_type:
  			compress_force = true;
  			/* Fallthrough */
  		case Opt_compress:
  		case Opt_compress_type:
  			if (token == Opt_compress ||
  			    token == Opt_compress_force ||
  			    strcmp(args[0].from, "zlib") == 0) {
  				compress_type = "zlib";
  				info->compress_type = BTRFS_COMPRESS_ZLIB;
  				btrfs_set_opt(info->mount_opt, COMPRESS);
  				btrfs_clear_opt(info->mount_opt, NODATACOW);
  				btrfs_clear_opt(info->mount_opt, NODATASUM);
  			} else if (strcmp(args[0].from, "lzo") == 0) {
  				compress_type = "lzo";
  				info->compress_type = BTRFS_COMPRESS_LZO;
  				btrfs_set_opt(info->mount_opt, COMPRESS);
  				btrfs_clear_opt(info->mount_opt, NODATACOW);
  				btrfs_clear_opt(info->mount_opt, NODATASUM);
  				btrfs_set_fs_incompat(info, COMPRESS_LZO);
  			} else if (strncmp(args[0].from, "no", 2) == 0) {
  				compress_type = "no";
  				btrfs_clear_opt(info->mount_opt, COMPRESS);
  				btrfs_clear_opt(info->mount_opt, FORCE_COMPRESS);
  				compress_force = false;
  			} else {
  				ret = -EINVAL;
  				goto out;
  			}
  
  			if (compress_force) {
  				btrfs_set_and_info(root, FORCE_COMPRESS,
  						   "force %s compression",
  						   compress_type);
  			} else {
  				if (!btrfs_test_opt(root, COMPRESS))
  					btrfs_info(root->fs_info,
  						   "btrfs: use %s compression",
  						   compress_type);
  				/*
  				 * If we remount from compress-force=xxx to
  				 * compress=xxx, we need clear FORCE_COMPRESS
  				 * flag, otherwise, there is no way for users
  				 * to disable forcible compression separately.
  				 */
  				btrfs_clear_opt(info->mount_opt, FORCE_COMPRESS);
  			}
  			break;
  		case Opt_ssd:
  			btrfs_set_and_info(root, SSD,
  					   "use ssd allocation scheme");
  			break;
  		case Opt_ssd_spread:
  			btrfs_set_and_info(root, SSD_SPREAD,
  					   "use spread ssd allocation scheme");
  			btrfs_set_opt(info->mount_opt, SSD);
  			break;
  		case Opt_nossd:
  			btrfs_set_and_info(root, NOSSD,
  					     "not using ssd allocation scheme");
  			btrfs_clear_opt(info->mount_opt, SSD);
  			break;
  		case Opt_barrier:
  			btrfs_clear_and_info(root, NOBARRIER,
  					     "turning on barriers");
  			break;
  		case Opt_nobarrier:
  			btrfs_set_and_info(root, NOBARRIER,
  					   "turning off barriers");
  			break;
  		case Opt_thread_pool:
  			ret = match_int(&args[0], &intarg);
  			if (ret) {
  				goto out;
  			} else if (intarg > 0) {
  				info->thread_pool_size = intarg;
  			} else {
  				ret = -EINVAL;
  				goto out;
  			}
  			break;
  		case Opt_max_inline:
  			num = match_strdup(&args[0]);
  			if (num) {
  				info->max_inline = memparse(num, NULL);
  				kfree(num);
  
  				if (info->max_inline) {
  					info->max_inline = min_t(u64,
  						info->max_inline,
  						root->sectorsize);
  				}
  				btrfs_info(root->fs_info, "max_inline at %llu",
  					info->max_inline);
  			} else {
  				ret = -ENOMEM;
  				goto out;
  			}
  			break;
  		case Opt_alloc_start:
  			num = match_strdup(&args[0]);
  			if (num) {
  				mutex_lock(&info->chunk_mutex);
  				info->alloc_start = memparse(num, NULL);
  				mutex_unlock(&info->chunk_mutex);
  				kfree(num);
  				btrfs_info(root->fs_info, "allocations start at %llu",
  					info->alloc_start);
  			} else {
  				ret = -ENOMEM;
  				goto out;
  			}
  			break;
  		case Opt_acl:
  #ifdef CONFIG_BTRFS_FS_POSIX_ACL
  			root->fs_info->sb->s_flags |= MS_POSIXACL;
  			break;
  #else
  			btrfs_err(root->fs_info,
  				"support for ACL not compiled in!");
  			ret = -EINVAL;
  			goto out;
  #endif
  		case Opt_noacl:
  			root->fs_info->sb->s_flags &= ~MS_POSIXACL;
  			break;
  		case Opt_notreelog:
  			btrfs_set_and_info(root, NOTREELOG,
  					   "disabling tree log");
  			break;
  		case Opt_treelog:
  			btrfs_clear_and_info(root, NOTREELOG,
  					     "enabling tree log");
  			break;
  		case Opt_flushoncommit:
  			btrfs_set_and_info(root, FLUSHONCOMMIT,
  					   "turning on flush-on-commit");
  			break;
  		case Opt_noflushoncommit:
  			btrfs_clear_and_info(root, FLUSHONCOMMIT,
  					     "turning off flush-on-commit");
  			break;
  		case Opt_ratio:
  			ret = match_int(&args[0], &intarg);
  			if (ret) {
  				goto out;
  			} else if (intarg >= 0) {
  				info->metadata_ratio = intarg;
  				btrfs_info(root->fs_info, "metadata ratio %d",
  				       info->metadata_ratio);
  			} else {
  				ret = -EINVAL;
  				goto out;
  			}
  			break;
  		case Opt_discard:
  			btrfs_set_and_info(root, DISCARD,
  					   "turning on discard");
  			break;
  		case Opt_nodiscard:
  			btrfs_clear_and_info(root, DISCARD,
  					     "turning off discard");
  			break;
  		case Opt_space_cache:
  			btrfs_set_and_info(root, SPACE_CACHE,
  					   "enabling disk space caching");
  			break;
  		case Opt_rescan_uuid_tree:
  			btrfs_set_opt(info->mount_opt, RESCAN_UUID_TREE);
  			break;
  		case Opt_no_space_cache:
  			btrfs_clear_and_info(root, SPACE_CACHE,
  					     "disabling disk space caching");
  			break;
  		case Opt_inode_cache:
  			btrfs_set_pending_and_info(info, INODE_MAP_CACHE,
  					   "enabling inode map caching");
  			break;
  		case Opt_noinode_cache:
  			btrfs_clear_pending_and_info(info, INODE_MAP_CACHE,
  					     "disabling inode map caching");
  			break;
  		case Opt_clear_cache:
  			btrfs_set_and_info(root, CLEAR_CACHE,
  					   "force clearing of disk cache");
  			break;
  		case Opt_user_subvol_rm_allowed:
  			btrfs_set_opt(info->mount_opt, USER_SUBVOL_RM_ALLOWED);
  			break;
  		case Opt_enospc_debug:
  			btrfs_set_opt(info->mount_opt, ENOSPC_DEBUG);
  			break;
  		case Opt_noenospc_debug:
  			btrfs_clear_opt(info->mount_opt, ENOSPC_DEBUG);
  			break;
  		case Opt_defrag:
  			btrfs_set_and_info(root, AUTO_DEFRAG,
  					   "enabling auto defrag");
  			break;
  		case Opt_nodefrag:
  			btrfs_clear_and_info(root, AUTO_DEFRAG,
  					     "disabling auto defrag");
  			break;
  		case Opt_recovery:
  			btrfs_info(root->fs_info, "enabling auto recovery");
  			btrfs_set_opt(info->mount_opt, RECOVERY);
  			break;
  		case Opt_skip_balance:
  			btrfs_set_opt(info->mount_opt, SKIP_BALANCE);
  			break;
  #ifdef CONFIG_BTRFS_FS_CHECK_INTEGRITY
  		case Opt_check_integrity_including_extent_data:
  			btrfs_info(root->fs_info,
  				   "enabling check integrity including extent data");
  			btrfs_set_opt(info->mount_opt,
  				      CHECK_INTEGRITY_INCLUDING_EXTENT_DATA);
  			btrfs_set_opt(info->mount_opt, CHECK_INTEGRITY);
  			break;
  		case Opt_check_integrity:
  			btrfs_info(root->fs_info, "enabling check integrity");
  			btrfs_set_opt(info->mount_opt, CHECK_INTEGRITY);
  			break;
  		case Opt_check_integrity_print_mask:
  			ret = match_int(&args[0], &intarg);
  			if (ret) {
  				goto out;
  			} else if (intarg >= 0) {
  				info->check_integrity_print_mask = intarg;
  				btrfs_info(root->fs_info, "check_integrity_print_mask 0x%x",
  				       info->check_integrity_print_mask);
  			} else {
  				ret = -EINVAL;
  				goto out;
  			}
  			break;
  #else
  		case Opt_check_integrity_including_extent_data:
  		case Opt_check_integrity:
  		case Opt_check_integrity_print_mask:
  			btrfs_err(root->fs_info,
  				"support for check_integrity* not compiled in!");
  			ret = -EINVAL;
  			goto out;
  #endif
  		case Opt_fatal_errors:
  			if (strcmp(args[0].from, "panic") == 0)
  				btrfs_set_opt(info->mount_opt,
  					      PANIC_ON_FATAL_ERROR);
  			else if (strcmp(args[0].from, "bug") == 0)
  				btrfs_clear_opt(info->mount_opt,
  					      PANIC_ON_FATAL_ERROR);
  			else {
  				ret = -EINVAL;
  				goto out;
  			}
  			break;
  		case Opt_commit_interval:
  			intarg = 0;
  			ret = match_int(&args[0], &intarg);
  			if (ret < 0) {
  				btrfs_err(root->fs_info, "invalid commit interval");
  				ret = -EINVAL;
  				goto out;
  			}
  			if (intarg > 0) {
  				if (intarg > 300) {
  					btrfs_warn(root->fs_info, "excessive commit interval %d",
  							intarg);
  				}
  				info->commit_interval = intarg;
  			} else {
  				btrfs_info(root->fs_info, "using default commit interval %ds",
  				    BTRFS_DEFAULT_COMMIT_INTERVAL);
  				info->commit_interval = BTRFS_DEFAULT_COMMIT_INTERVAL;
  			}
  			break;
  		case Opt_err:
  			btrfs_info(root->fs_info, "unrecognized mount option '%s'", p);
  			ret = -EINVAL;
  			goto out;
  		default:
  			break;
  		}
  	}
  out:
  	if (!ret && btrfs_test_opt(root, SPACE_CACHE))
  		btrfs_info(root->fs_info, "disk space caching is enabled");
  	kfree(orig);
  	return ret;
  }
  
  /*
   * Parse mount options that are required early in the mount process.
   *
   * All other options will be parsed on much later in the mount process and
   * only when we need to allocate a new super block.
   */
  static int btrfs_parse_early_options(const char *options, fmode_t flags,
  		void *holder, char **subvol_name, u64 *subvol_objectid,
  		struct btrfs_fs_devices **fs_devices)
  {
  	substring_t args[MAX_OPT_ARGS];
  	char *device_name, *opts, *orig, *p;
  	char *num = NULL;
  	int error = 0;
  
  	if (!options)
  		return 0;
  
  	/*
  	 * strsep changes the string, duplicate it because parse_options
  	 * gets called twice
  	 */
  	opts = kstrdup(options, GFP_KERNEL);
  	if (!opts)
  		return -ENOMEM;
  	orig = opts;
  
  	while ((p = strsep(&opts, ",")) != NULL) {
  		int token;
  		if (!*p)
  			continue;
  
  		token = match_token(p, tokens, args);
  		switch (token) {
  		case Opt_subvol:
  			kfree(*subvol_name);
  			*subvol_name = match_strdup(&args[0]);
  			if (!*subvol_name) {
  				error = -ENOMEM;
  				goto out;
  			}
  			break;
  		case Opt_subvolid:
  			num = match_strdup(&args[0]);
  			if (num) {
  				*subvol_objectid = memparse(num, NULL);
  				kfree(num);
  				/* we want the original fs_tree */
  				if (!*subvol_objectid)
  					*subvol_objectid =
  						BTRFS_FS_TREE_OBJECTID;
  			} else {
  				error = -EINVAL;
  				goto out;
  			}
  			break;
  		case Opt_subvolrootid:
  			printk(KERN_WARNING
  				"BTRFS: 'subvolrootid' mount option is deprecated and has "
  				"no effect\n");
  			break;
  		case Opt_device:
  			device_name = match_strdup(&args[0]);
  			if (!device_name) {
  				error = -ENOMEM;
  				goto out;
  			}
  			error = btrfs_scan_one_device(device_name,
  					flags, holder, fs_devices);
  			kfree(device_name);
  			if (error)
  				goto out;
  			break;
  		default:
  			break;
  		}
  	}
  
  out:
  	kfree(orig);
  	return error;
  }
  
  static char *get_subvol_name_from_objectid(struct btrfs_fs_info *fs_info,
  					   u64 subvol_objectid)
  {
  	struct btrfs_root *root = fs_info->tree_root;
  	struct btrfs_root *fs_root;
  	struct btrfs_root_ref *root_ref;
  	struct btrfs_inode_ref *inode_ref;
  	struct btrfs_key key;
  	struct btrfs_path *path = NULL;
  	char *name = NULL, *ptr;
  	u64 dirid;
  	int len;
  	int ret;
  
  	path = btrfs_alloc_path();
  	if (!path) {
  		ret = -ENOMEM;
  		goto err;
  	}
  	path->leave_spinning = 1;
  
  	name = kmalloc(PATH_MAX, GFP_NOFS);
  	if (!name) {
  		ret = -ENOMEM;
  		goto err;
  	}
  	ptr = name + PATH_MAX - 1;
  	ptr[0] = '\0';
  
  	/*
  	 * Walk up the subvolume trees in the tree of tree roots by root
  	 * backrefs until we hit the top-level subvolume.
  	 */
  	while (subvol_objectid != BTRFS_FS_TREE_OBJECTID) {
  		key.objectid = subvol_objectid;
  		key.type = BTRFS_ROOT_BACKREF_KEY;
  		key.offset = (u64)-1;
  
  		ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
  		if (ret < 0) {
  			goto err;
  		} else if (ret > 0) {
  			ret = btrfs_previous_item(root, path, subvol_objectid,
  						  BTRFS_ROOT_BACKREF_KEY);
  			if (ret < 0) {
  				goto err;
  			} else if (ret > 0) {
  				ret = -ENOENT;
  				goto err;
  			}
  		}
  
  		btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
  		subvol_objectid = key.offset;
  
  		root_ref = btrfs_item_ptr(path->nodes[0], path->slots[0],
  					  struct btrfs_root_ref);
  		len = btrfs_root_ref_name_len(path->nodes[0], root_ref);
  		ptr -= len + 1;
  		if (ptr < name) {
  			ret = -ENAMETOOLONG;
  			goto err;
  		}
  		read_extent_buffer(path->nodes[0], ptr + 1,
  				   (unsigned long)(root_ref + 1), len);
  		ptr[0] = '/';
  		dirid = btrfs_root_ref_dirid(path->nodes[0], root_ref);
  		btrfs_release_path(path);
  
  		key.objectid = subvol_objectid;
  		key.type = BTRFS_ROOT_ITEM_KEY;
  		key.offset = (u64)-1;
  		fs_root = btrfs_read_fs_root_no_name(fs_info, &key);
  		if (IS_ERR(fs_root)) {
  			ret = PTR_ERR(fs_root);
  			goto err;
  		}
  
  		/*
  		 * Walk up the filesystem tree by inode refs until we hit the
  		 * root directory.
  		 */
  		while (dirid != BTRFS_FIRST_FREE_OBJECTID) {
  			key.objectid = dirid;
  			key.type = BTRFS_INODE_REF_KEY;
  			key.offset = (u64)-1;
  
  			ret = btrfs_search_slot(NULL, fs_root, &key, path, 0, 0);
  			if (ret < 0) {
  				goto err;
  			} else if (ret > 0) {
  				ret = btrfs_previous_item(fs_root, path, dirid,
  							  BTRFS_INODE_REF_KEY);
  				if (ret < 0) {
  					goto err;
  				} else if (ret > 0) {
  					ret = -ENOENT;
  					goto err;
  				}
  			}
  
  			btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
  			dirid = key.offset;
  
  			inode_ref = btrfs_item_ptr(path->nodes[0],
  						   path->slots[0],
  						   struct btrfs_inode_ref);
  			len = btrfs_inode_ref_name_len(path->nodes[0],
  						       inode_ref);
  			ptr -= len + 1;
  			if (ptr < name) {
  				ret = -ENAMETOOLONG;
  				goto err;
  			}
  			read_extent_buffer(path->nodes[0], ptr + 1,
  					   (unsigned long)(inode_ref + 1), len);
  			ptr[0] = '/';
  			btrfs_release_path(path);
  		}
  	}
  
  	btrfs_free_path(path);
  	if (ptr == name + PATH_MAX - 1) {
  		name[0] = '/';
  		name[1] = '\0';
  	} else {
  		memmove(name, ptr, name + PATH_MAX - ptr);
  	}
  	return name;
  
  err:
  	btrfs_free_path(path);
  	kfree(name);
  	return ERR_PTR(ret);
  }
  
  static int get_default_subvol_objectid(struct btrfs_fs_info *fs_info, u64 *objectid)
  {
  	struct btrfs_root *root = fs_info->tree_root;
  	struct btrfs_dir_item *di;
  	struct btrfs_path *path;
  	struct btrfs_key location;
  	u64 dir_id;
  
  	path = btrfs_alloc_path();
  	if (!path)
  		return -ENOMEM;
  	path->leave_spinning = 1;
  
  	/*
  	 * Find the "default" dir item which points to the root item that we
  	 * will mount by default if we haven't been given a specific subvolume
  	 * to mount.
  	 */
  	dir_id = btrfs_super_root_dir(fs_info->super_copy);
  	di = btrfs_lookup_dir_item(NULL, root, path, dir_id, "default", 7, 0);
  	if (IS_ERR(di)) {
  		btrfs_free_path(path);
  		return PTR_ERR(di);
  	}
  	if (!di) {
  		/*
  		 * Ok the default dir item isn't there.  This is weird since
  		 * it's always been there, but don't freak out, just try and
  		 * mount the top-level subvolume.
  		 */
  		btrfs_free_path(path);
  		*objectid = BTRFS_FS_TREE_OBJECTID;
  		return 0;
  	}
  
  	btrfs_dir_item_key_to_cpu(path->nodes[0], di, &location);
  	btrfs_free_path(path);
  	*objectid = location.objectid;
  	return 0;
  }
  
  static int btrfs_fill_super(struct super_block *sb,
  			    struct btrfs_fs_devices *fs_devices,
  			    void *data, int silent)
  {
  	struct inode *inode;
  	struct btrfs_fs_info *fs_info = btrfs_sb(sb);
  	struct btrfs_key key;
  	int err;
  
  	sb->s_maxbytes = MAX_LFS_FILESIZE;
  	sb->s_magic = BTRFS_SUPER_MAGIC;
  	sb->s_op = &btrfs_super_ops;
  	sb->s_d_op = &btrfs_dentry_operations;
  	sb->s_export_op = &btrfs_export_ops;
  	sb->s_xattr = btrfs_xattr_handlers;
  	sb->s_time_gran = 1;
  #ifdef CONFIG_BTRFS_FS_POSIX_ACL
  	sb->s_flags |= MS_POSIXACL;
  #endif
  	sb->s_flags |= MS_I_VERSION;
  	err = open_ctree(sb, fs_devices, (char *)data);
  	if (err) {
  		printk(KERN_ERR "BTRFS: open_ctree failed\n");
  		return err;
  	}
  
  	key.objectid = BTRFS_FIRST_FREE_OBJECTID;
  	key.type = BTRFS_INODE_ITEM_KEY;
  	key.offset = 0;
  	inode = btrfs_iget(sb, &key, fs_info->fs_root, NULL);
  	if (IS_ERR(inode)) {
  		err = PTR_ERR(inode);
  		goto fail_close;
  	}
  
  	sb->s_root = d_make_root(inode);
  	if (!sb->s_root) {
  		err = -ENOMEM;
  		goto fail_close;
  	}
  
  	save_mount_options(sb, data);
  	cleancache_init_fs(sb);
  	sb->s_flags |= MS_ACTIVE;
  	return 0;
  
  fail_close:
  	close_ctree(fs_info->tree_root);
  	return err;
  }
  
  int btrfs_sync_fs(struct super_block *sb, int wait)
  {
  	struct btrfs_trans_handle *trans;
  	struct btrfs_fs_info *fs_info = btrfs_sb(sb);
  	struct btrfs_root *root = fs_info->tree_root;
  
  	trace_btrfs_sync_fs(wait);
  
  	if (!wait) {
  		filemap_flush(fs_info->btree_inode->i_mapping);
  		return 0;
  	}
  
  	btrfs_wait_ordered_roots(fs_info, -1);
  
  	trans = btrfs_attach_transaction_barrier(root);
  	if (IS_ERR(trans)) {
  		/* no transaction, don't bother */
  		if (PTR_ERR(trans) == -ENOENT) {
  			/*
  			 * Exit unless we have some pending changes
  			 * that need to go through commit
  			 */
  			if (fs_info->pending_changes == 0)
  				return 0;
  			/*
  			 * A non-blocking test if the fs is frozen. We must not
  			 * start a new transaction here otherwise a deadlock
  			 * happens. The pending operations are delayed to the
  			 * next commit after thawing.
  			 */
  			if (__sb_start_write(sb, SB_FREEZE_WRITE, false))
  				__sb_end_write(sb, SB_FREEZE_WRITE);
  			else
  				return 0;
  			trans = btrfs_start_transaction(root, 0);
  		}
  		if (IS_ERR(trans))
  			return PTR_ERR(trans);
  	}
  	return btrfs_commit_transaction(trans, root);
  }
  
  static int btrfs_show_options(struct seq_file *seq, struct dentry *dentry)
  {
  	struct btrfs_fs_info *info = btrfs_sb(dentry->d_sb);
  	struct btrfs_root *root = info->tree_root;
  	char *compress_type;
  
  	if (btrfs_test_opt(root, DEGRADED))
  		seq_puts(seq, ",degraded");
  	if (btrfs_test_opt(root, NODATASUM))
  		seq_puts(seq, ",nodatasum");
  	if (btrfs_test_opt(root, NODATACOW))
  		seq_puts(seq, ",nodatacow");
  	if (btrfs_test_opt(root, NOBARRIER))
  		seq_puts(seq, ",nobarrier");
  	if (info->max_inline != BTRFS_DEFAULT_MAX_INLINE)
  		seq_printf(seq, ",max_inline=%llu", info->max_inline);
  	if (info->alloc_start != 0)
  		seq_printf(seq, ",alloc_start=%llu", info->alloc_start);
  	if (info->thread_pool_size !=  min_t(unsigned long,
  					     num_online_cpus() + 2, 8))
  		seq_printf(seq, ",thread_pool=%d", info->thread_pool_size);
  	if (btrfs_test_opt(root, COMPRESS)) {
  		if (info->compress_type == BTRFS_COMPRESS_ZLIB)
  			compress_type = "zlib";
  		else
  			compress_type = "lzo";
  		if (btrfs_test_opt(root, FORCE_COMPRESS))
  			seq_printf(seq, ",compress-force=%s", compress_type);
  		else
  			seq_printf(seq, ",compress=%s", compress_type);
  	}
  	if (btrfs_test_opt(root, NOSSD))
  		seq_puts(seq, ",nossd");
  	if (btrfs_test_opt(root, SSD_SPREAD))
  		seq_puts(seq, ",ssd_spread");
  	else if (btrfs_test_opt(root, SSD))
  		seq_puts(seq, ",ssd");
  	if (btrfs_test_opt(root, NOTREELOG))
  		seq_puts(seq, ",notreelog");
  	if (btrfs_test_opt(root, FLUSHONCOMMIT))
  		seq_puts(seq, ",flushoncommit");
  	if (btrfs_test_opt(root, DISCARD))
  		seq_puts(seq, ",discard");
  	if (!(root->fs_info->sb->s_flags & MS_POSIXACL))
  		seq_puts(seq, ",noacl");
  	if (btrfs_test_opt(root, SPACE_CACHE))
  		seq_puts(seq, ",space_cache");
  	else
  		seq_puts(seq, ",nospace_cache");
  	if (btrfs_test_opt(root, RESCAN_UUID_TREE))
  		seq_puts(seq, ",rescan_uuid_tree");
  	if (btrfs_test_opt(root, CLEAR_CACHE))
  		seq_puts(seq, ",clear_cache");
  	if (btrfs_test_opt(root, USER_SUBVOL_RM_ALLOWED))
  		seq_puts(seq, ",user_subvol_rm_allowed");
  	if (btrfs_test_opt(root, ENOSPC_DEBUG))
  		seq_puts(seq, ",enospc_debug");
  	if (btrfs_test_opt(root, AUTO_DEFRAG))
  		seq_puts(seq, ",autodefrag");
  	if (btrfs_test_opt(root, INODE_MAP_CACHE))
  		seq_puts(seq, ",inode_cache");
  	if (btrfs_test_opt(root, SKIP_BALANCE))
  		seq_puts(seq, ",skip_balance");
  	if (btrfs_test_opt(root, RECOVERY))
  		seq_puts(seq, ",recovery");
  #ifdef CONFIG_BTRFS_FS_CHECK_INTEGRITY
  	if (btrfs_test_opt(root, CHECK_INTEGRITY_INCLUDING_EXTENT_DATA))
  		seq_puts(seq, ",check_int_data");
  	else if (btrfs_test_opt(root, CHECK_INTEGRITY))
  		seq_puts(seq, ",check_int");
  	if (info->check_integrity_print_mask)
  		seq_printf(seq, ",check_int_print_mask=%d",
  				info->check_integrity_print_mask);
  #endif
  	if (info->metadata_ratio)
  		seq_printf(seq, ",metadata_ratio=%d",
  				info->metadata_ratio);
  	if (btrfs_test_opt(root, PANIC_ON_FATAL_ERROR))
  		seq_puts(seq, ",fatal_errors=panic");
  	if (info->commit_interval != BTRFS_DEFAULT_COMMIT_INTERVAL)
  		seq_printf(seq, ",commit=%d", info->commit_interval);
  	seq_printf(seq, ",subvolid=%llu",
  		  BTRFS_I(d_inode(dentry))->root->root_key.objectid);
  	seq_puts(seq, ",subvol=");
  	seq_dentry(seq, dentry, " \t\n\\");
  	return 0;
  }
  
  static int btrfs_test_super(struct super_block *s, void *data)
  {
  	struct btrfs_fs_info *p = data;
  	struct btrfs_fs_info *fs_info = btrfs_sb(s);
  
  	return fs_info->fs_devices == p->fs_devices;
  }
  
  static int btrfs_set_super(struct super_block *s, void *data)
  {
  	int err = set_anon_super(s, data);
  	if (!err)
  		s->s_fs_info = data;
  	return err;
  }
  
  /*
   * subvolumes are identified by ino 256
   */
  static inline int is_subvolume_inode(struct inode *inode)
  {
  	if (inode && inode->i_ino == BTRFS_FIRST_FREE_OBJECTID)
  		return 1;
  	return 0;
  }
  
  /*
   * This will add subvolid=0 to the argument string while removing any subvol=
   * and subvolid= arguments to make sure we get the top-level root for path
   * walking to the subvol we want.
   */
  static char *setup_root_args(char *args)
  {
  	char *buf, *dst, *sep;
  
  	if (!args)
  		return kstrdup("subvolid=0", GFP_NOFS);
  
  	/* The worst case is that we add ",subvolid=0" to the end. */
  	buf = dst = kmalloc(strlen(args) + strlen(",subvolid=0") + 1, GFP_NOFS);
  	if (!buf)
  		return NULL;
  
  	while (1) {
  		sep = strchrnul(args, ',');
  		if (!strstarts(args, "subvol=") &&
  		    !strstarts(args, "subvolid=")) {
  			memcpy(dst, args, sep - args);
  			dst += sep - args;
  			*dst++ = ',';
  		}
  		if (*sep)
  			args = sep + 1;
  		else
  			break;
  	}
  	strcpy(dst, "subvolid=0");
  
  	return buf;
  }
  
  static struct dentry *mount_subvol(const char *subvol_name, u64 subvol_objectid,
  				   int flags, const char *device_name,
  				   char *data)
  {
  	struct dentry *root;
  	struct vfsmount *mnt = NULL;
  	char *newargs;
  	int ret;
  
  	newargs = setup_root_args(data);
  	if (!newargs) {
  		root = ERR_PTR(-ENOMEM);
  		goto out;
  	}
  
  	mnt = vfs_kern_mount(&btrfs_fs_type, flags, device_name, newargs);
  	if (PTR_ERR_OR_ZERO(mnt) == -EBUSY) {
  		if (flags & MS_RDONLY) {
  			mnt = vfs_kern_mount(&btrfs_fs_type, flags & ~MS_RDONLY,
  					     device_name, newargs);
  		} else {
  			mnt = vfs_kern_mount(&btrfs_fs_type, flags | MS_RDONLY,
  					     device_name, newargs);
  			if (IS_ERR(mnt)) {
  				root = ERR_CAST(mnt);
  				mnt = NULL;
  				goto out;
  			}
  
  			down_write(&mnt->mnt_sb->s_umount);
  			ret = btrfs_remount(mnt->mnt_sb, &flags, NULL);
  			up_write(&mnt->mnt_sb->s_umount);
  			if (ret < 0) {
  				root = ERR_PTR(ret);
  				goto out;
  			}
  		}
  	}
  	if (IS_ERR(mnt)) {
  		root = ERR_CAST(mnt);
  		mnt = NULL;
  		goto out;
  	}
  
  	if (!subvol_name) {
  		if (!subvol_objectid) {
  			ret = get_default_subvol_objectid(btrfs_sb(mnt->mnt_sb),
  							  &subvol_objectid);
  			if (ret) {
  				root = ERR_PTR(ret);
  				goto out;
  			}
  		}
  		subvol_name = get_subvol_name_from_objectid(btrfs_sb(mnt->mnt_sb),
  							    subvol_objectid);
  		if (IS_ERR(subvol_name)) {
  			root = ERR_CAST(subvol_name);
  			subvol_name = NULL;
  			goto out;
  		}
  
  	}
  
  	root = mount_subtree(mnt, subvol_name);
  	/* mount_subtree() drops our reference on the vfsmount. */
  	mnt = NULL;
  
  	if (!IS_ERR(root)) {
  		struct super_block *s = root->d_sb;
  		struct inode *root_inode = d_inode(root);
  		u64 root_objectid = BTRFS_I(root_inode)->root->root_key.objectid;
  
  		ret = 0;
  		if (!is_subvolume_inode(root_inode)) {
  			pr_err("BTRFS: '%s' is not a valid subvolume\n",
  			       subvol_name);
  			ret = -EINVAL;
  		}
  		if (subvol_objectid && root_objectid != subvol_objectid) {
  			/*
  			 * This will also catch a race condition where a
  			 * subvolume which was passed by ID is renamed and
  			 * another subvolume is renamed over the old location.
  			 */
  			pr_err("BTRFS: subvol '%s' does not match subvolid %llu\n",
  			       subvol_name, subvol_objectid);
  			ret = -EINVAL;
  		}
  		if (ret) {
  			dput(root);
  			root = ERR_PTR(ret);
  			deactivate_locked_super(s);
  		}
  	}
  
  out:
  	mntput(mnt);
  	kfree(newargs);
  	kfree(subvol_name);
  	return root;
  }
  
  static int parse_security_options(char *orig_opts,
  				  struct security_mnt_opts *sec_opts)
  {
  	char *secdata = NULL;
  	int ret = 0;
  
  	secdata = alloc_secdata();
  	if (!secdata)
  		return -ENOMEM;
  	ret = security_sb_copy_data(orig_opts, secdata);
  	if (ret) {
  		free_secdata(secdata);
  		return ret;
  	}
  	ret = security_sb_parse_opts_str(secdata, sec_opts);
  	free_secdata(secdata);
  	return ret;
  }
  
  static int setup_security_options(struct btrfs_fs_info *fs_info,
  				  struct super_block *sb,
  				  struct security_mnt_opts *sec_opts)
  {
  	int ret = 0;
  
  	/*
  	 * Call security_sb_set_mnt_opts() to check whether new sec_opts
  	 * is valid.
  	 */
  	ret = security_sb_set_mnt_opts(sb, sec_opts, 0, NULL);
  	if (ret)
  		return ret;
  
  #ifdef CONFIG_SECURITY
  	if (!fs_info->security_opts.num_mnt_opts) {
  		/* first time security setup, copy sec_opts to fs_info */
  		memcpy(&fs_info->security_opts, sec_opts, sizeof(*sec_opts));
  	} else {
  		/*
  		 * Since SELinux(the only one supports security_mnt_opts) does
  		 * NOT support changing context during remount/mount same sb,
  		 * This must be the same or part of the same security options,
  		 * just free it.
  		 */
  		security_free_mnt_opts(sec_opts);
  	}
  #endif
  	return ret;
  }
  
  /*
   * Find a superblock for the given device / mount point.
   *
   * Note:  This is based on get_sb_bdev from fs/super.c with a few additions
   *	  for multiple device setup.  Make sure to keep it in sync.
   */
  static struct dentry *btrfs_mount(struct file_system_type *fs_type, int flags,
  		const char *device_name, void *data)
  {
  	struct block_device *bdev = NULL;
  	struct super_block *s;
  	struct btrfs_fs_devices *fs_devices = NULL;
  	struct btrfs_fs_info *fs_info = NULL;
  	struct security_mnt_opts new_sec_opts;
  	fmode_t mode = FMODE_READ;
  	char *subvol_name = NULL;
  	u64 subvol_objectid = 0;
  	int error = 0;
  
  	if (!(flags & MS_RDONLY))
  		mode |= FMODE_WRITE;
  
  	error = btrfs_parse_early_options(data, mode, fs_type,
  					  &subvol_name, &subvol_objectid,
  					  &fs_devices);
  	if (error) {
  		kfree(subvol_name);
  		return ERR_PTR(error);
  	}
  
  	if (subvol_name || subvol_objectid != BTRFS_FS_TREE_OBJECTID) {
  		/* mount_subvol() will free subvol_name. */
  		return mount_subvol(subvol_name, subvol_objectid, flags,
  				    device_name, data);
  	}
  
  	security_init_mnt_opts(&new_sec_opts);
  	if (data) {
  		error = parse_security_options(data, &new_sec_opts);
  		if (error)
  			return ERR_PTR(error);
  	}
  
  	error = btrfs_scan_one_device(device_name, mode, fs_type, &fs_devices);
  	if (error)
  		goto error_sec_opts;
  
  	/*
  	 * Setup a dummy root and fs_info for test/set super.  This is because
  	 * we don't actually fill this stuff out until open_ctree, but we need
  	 * it for searching for existing supers, so this lets us do that and
  	 * then open_ctree will properly initialize everything later.
  	 */
  	fs_info = kzalloc(sizeof(struct btrfs_fs_info), GFP_NOFS);
  	if (!fs_info) {
  		error = -ENOMEM;
  		goto error_sec_opts;
  	}
  
  	fs_info->fs_devices = fs_devices;
  
  	fs_info->super_copy = kzalloc(BTRFS_SUPER_INFO_SIZE, GFP_NOFS);
  	fs_info->super_for_commit = kzalloc(BTRFS_SUPER_INFO_SIZE, GFP_NOFS);
  	security_init_mnt_opts(&fs_info->security_opts);
  	if (!fs_info->super_copy || !fs_info->super_for_commit) {
  		error = -ENOMEM;
  		goto error_fs_info;
  	}
  
  	error = btrfs_open_devices(fs_devices, mode, fs_type);
  	if (error)
  		goto error_fs_info;
  
  	if (!(flags & MS_RDONLY) && fs_devices->rw_devices == 0) {
  		error = -EACCES;
  		goto error_close_devices;
  	}
  
  	bdev = fs_devices->latest_bdev;
  	s = sget(fs_type, btrfs_test_super, btrfs_set_super, flags | MS_NOSEC,
  		 fs_info);
  	if (IS_ERR(s)) {
  		error = PTR_ERR(s);
  		goto error_close_devices;
  	}
  
  	if (s->s_root) {
  		btrfs_close_devices(fs_devices);
  		free_fs_info(fs_info);
  		if ((flags ^ s->s_flags) & MS_RDONLY)
  			error = -EBUSY;
  	} else {
  		char b[BDEVNAME_SIZE];
  
  		strlcpy(s->s_id, bdevname(bdev, b), sizeof(s->s_id));
  		btrfs_sb(s)->bdev_holder = fs_type;
  		error = btrfs_fill_super(s, fs_devices, data,
  					 flags & MS_SILENT ? 1 : 0);
  	}
  	if (error) {
  		deactivate_locked_super(s);
  		goto error_sec_opts;
  	}
  
  	fs_info = btrfs_sb(s);
  	error = setup_security_options(fs_info, s, &new_sec_opts);
  	if (error) {
  		deactivate_locked_super(s);
  		goto error_sec_opts;
  	}
  
  	return dget(s->s_root);
  
  error_close_devices:
  	btrfs_close_devices(fs_devices);
  error_fs_info:
  	free_fs_info(fs_info);
  error_sec_opts:
  	security_free_mnt_opts(&new_sec_opts);
  	return ERR_PTR(error);
  }
  
  static void btrfs_resize_thread_pool(struct btrfs_fs_info *fs_info,
  				     int new_pool_size, int old_pool_size)
  {
  	if (new_pool_size == old_pool_size)
  		return;
  
  	fs_info->thread_pool_size = new_pool_size;
  
  	btrfs_info(fs_info, "resize thread pool %d -> %d",
  	       old_pool_size, new_pool_size);
  
  	btrfs_workqueue_set_max(fs_info->workers, new_pool_size);
  	btrfs_workqueue_set_max(fs_info->delalloc_workers, new_pool_size);
  	btrfs_workqueue_set_max(fs_info->submit_workers, new_pool_size);
  	btrfs_workqueue_set_max(fs_info->caching_workers, new_pool_size);
  	btrfs_workqueue_set_max(fs_info->endio_workers, new_pool_size);
  	btrfs_workqueue_set_max(fs_info->endio_meta_workers, new_pool_size);
  	btrfs_workqueue_set_max(fs_info->endio_meta_write_workers,
  				new_pool_size);
  	btrfs_workqueue_set_max(fs_info->endio_write_workers, new_pool_size);
  	btrfs_workqueue_set_max(fs_info->endio_freespace_worker, new_pool_size);
  	btrfs_workqueue_set_max(fs_info->delayed_workers, new_pool_size);
  	btrfs_workqueue_set_max(fs_info->readahead_workers, new_pool_size);
  	btrfs_workqueue_set_max(fs_info->scrub_wr_completion_workers,
  				new_pool_size);
  }
  
  static inline void btrfs_remount_prepare(struct btrfs_fs_info *fs_info)
  {
  	set_bit(BTRFS_FS_STATE_REMOUNTING, &fs_info->fs_state);
  }
  
  static inline void btrfs_remount_begin(struct btrfs_fs_info *fs_info,
  				       unsigned long old_opts, int flags)
  {
  	if (btrfs_raw_test_opt(old_opts, AUTO_DEFRAG) &&
  	    (!btrfs_raw_test_opt(fs_info->mount_opt, AUTO_DEFRAG) ||
  	     (flags & MS_RDONLY))) {
  		/* wait for any defraggers to finish */
  		wait_event(fs_info->transaction_wait,
  			   (atomic_read(&fs_info->defrag_running) == 0));
  		if (flags & MS_RDONLY)
  			sync_filesystem(fs_info->sb);
  	}
  }
  
  static inline void btrfs_remount_cleanup(struct btrfs_fs_info *fs_info,
  					 unsigned long old_opts)
  {
  	/*
  	 * We need cleanup all defragable inodes if the autodefragment is
  	 * close or the fs is R/O.
  	 */
  	if (btrfs_raw_test_opt(old_opts, AUTO_DEFRAG) &&
  	    (!btrfs_raw_test_opt(fs_info->mount_opt, AUTO_DEFRAG) ||
  	     (fs_info->sb->s_flags & MS_RDONLY))) {
  		btrfs_cleanup_defrag_inodes(fs_info);
  	}
  
  	clear_bit(BTRFS_FS_STATE_REMOUNTING, &fs_info->fs_state);
  }
  
  static int btrfs_remount(struct super_block *sb, int *flags, char *data)
  {
  	struct btrfs_fs_info *fs_info = btrfs_sb(sb);
  	struct btrfs_root *root = fs_info->tree_root;
  	unsigned old_flags = sb->s_flags;
  	unsigned long old_opts = fs_info->mount_opt;
  	unsigned long old_compress_type = fs_info->compress_type;
  	u64 old_max_inline = fs_info->max_inline;
  	u64 old_alloc_start = fs_info->alloc_start;
  	int old_thread_pool_size = fs_info->thread_pool_size;
  	unsigned int old_metadata_ratio = fs_info->metadata_ratio;
  	int ret;
  
  	sync_filesystem(sb);
  	btrfs_remount_prepare(fs_info);
  
  	if (data) {
  		struct security_mnt_opts new_sec_opts;
  
  		security_init_mnt_opts(&new_sec_opts);
  		ret = parse_security_options(data, &new_sec_opts);
  		if (ret)
  			goto restore;
  		ret = setup_security_options(fs_info, sb,
  					     &new_sec_opts);
  		if (ret) {
  			security_free_mnt_opts(&new_sec_opts);
  			goto restore;
  		}
  	}
  
  	ret = btrfs_parse_options(root, data);
  	if (ret) {
  		ret = -EINVAL;
  		goto restore;
  	}
  
  	btrfs_remount_begin(fs_info, old_opts, *flags);
  	btrfs_resize_thread_pool(fs_info,
  		fs_info->thread_pool_size, old_thread_pool_size);
  
  	if ((*flags & MS_RDONLY) == (sb->s_flags & MS_RDONLY))
  		goto out;
  
  	if (*flags & MS_RDONLY) {
  		/*
  		 * this also happens on 'umount -rf' or on shutdown, when
  		 * the filesystem is busy.
  		 */
  		cancel_work_sync(&fs_info->async_reclaim_work);
  
  		/* wait for the uuid_scan task to finish */
  		down(&fs_info->uuid_tree_rescan_sem);
  		/* avoid complains from lockdep et al. */
  		up(&fs_info->uuid_tree_rescan_sem);
  
  		sb->s_flags |= MS_RDONLY;
  
  		btrfs_dev_replace_suspend_for_unmount(fs_info);
  		btrfs_scrub_cancel(fs_info);
  		btrfs_pause_balance(fs_info);
  
  		ret = btrfs_commit_super(root);
  		if (ret)
  			goto restore;
  	} else {
  		if (test_bit(BTRFS_FS_STATE_ERROR, &root->fs_info->fs_state)) {
  			btrfs_err(fs_info,
  				"Remounting read-write after error is not allowed");
  			ret = -EINVAL;
  			goto restore;
  		}
  		if (fs_info->fs_devices->rw_devices == 0) {
  			ret = -EACCES;
  			goto restore;
  		}
  
  		if (fs_info->fs_devices->missing_devices >
  		     fs_info->num_tolerated_disk_barrier_failures &&
  		    !(*flags & MS_RDONLY)) {
  			btrfs_warn(fs_info,
  				"too many missing devices, writeable remount is not allowed");
  			ret = -EACCES;
  			goto restore;
  		}
  
  		if (btrfs_super_log_root(fs_info->super_copy) != 0) {
  			ret = -EINVAL;
  			goto restore;
  		}
  
  		ret = btrfs_cleanup_fs_roots(fs_info);
  		if (ret)
  			goto restore;
  
  		/* recover relocation */
  		mutex_lock(&fs_info->cleaner_mutex);
  		ret = btrfs_recover_relocation(root);
  		mutex_unlock(&fs_info->cleaner_mutex);
  		if (ret)
  			goto restore;
  
  		ret = btrfs_resume_balance_async(fs_info);
  		if (ret)
  			goto restore;
  
  		ret = btrfs_resume_dev_replace_async(fs_info);
  		if (ret) {
  			btrfs_warn(fs_info, "failed to resume dev_replace");
  			goto restore;
  		}
  
  		if (!fs_info->uuid_root) {
  			btrfs_info(fs_info, "creating UUID tree");
  			ret = btrfs_create_uuid_tree(fs_info);
  			if (ret) {
  				btrfs_warn(fs_info, "failed to create the UUID tree %d", ret);
  				goto restore;
  			}
  		}
  		sb->s_flags &= ~MS_RDONLY;
  	}
  out:
  	wake_up_process(fs_info->transaction_kthread);
  	btrfs_remount_cleanup(fs_info, old_opts);
  	return 0;
  
  restore:
  	/* We've hit an error - don't reset MS_RDONLY */
  	if (sb->s_flags & MS_RDONLY)
  		old_flags |= MS_RDONLY;
  	sb->s_flags = old_flags;
  	fs_info->mount_opt = old_opts;
  	fs_info->compress_type = old_compress_type;
  	fs_info->max_inline = old_max_inline;
  	mutex_lock(&fs_info->chunk_mutex);
  	fs_info->alloc_start = old_alloc_start;
  	mutex_unlock(&fs_info->chunk_mutex);
  	btrfs_resize_thread_pool(fs_info,
  		old_thread_pool_size, fs_info->thread_pool_size);
  	fs_info->metadata_ratio = old_metadata_ratio;
  	btrfs_remount_cleanup(fs_info, old_opts);
  	return ret;
  }
  
  /* Used to sort the devices by max_avail(descending sort) */
  static int btrfs_cmp_device_free_bytes(const void *dev_info1,
  				       const void *dev_info2)
  {
  	if (((struct btrfs_device_info *)dev_info1)->max_avail >
  	    ((struct btrfs_device_info *)dev_info2)->max_avail)
  		return -1;
  	else if (((struct btrfs_device_info *)dev_info1)->max_avail <
  		 ((struct btrfs_device_info *)dev_info2)->max_avail)
  		return 1;
  	else
  	return 0;
  }
  
  /*
   * sort the devices by max_avail, in which max free extent size of each device
   * is stored.(Descending Sort)
   */
  static inline void btrfs_descending_sort_devices(
  					struct btrfs_device_info *devices,
  					size_t nr_devices)
  {
  	sort(devices, nr_devices, sizeof(struct btrfs_device_info),
  	     btrfs_cmp_device_free_bytes, NULL);
  }
  
  /*
   * The helper to calc the free space on the devices that can be used to store
   * file data.
   */
  static int btrfs_calc_avail_data_space(struct btrfs_root *root, u64 *free_bytes)
  {
  	struct btrfs_fs_info *fs_info = root->fs_info;
  	struct btrfs_device_info *devices_info;
  	struct btrfs_fs_devices *fs_devices = fs_info->fs_devices;
  	struct btrfs_device *device;
  	u64 skip_space;
  	u64 type;
  	u64 avail_space;
  	u64 used_space;
  	u64 min_stripe_size;
  	int min_stripes = 1, num_stripes = 1;
  	int i = 0, nr_devices;
  	int ret;
  
  	/*
  	 * We aren't under the device list lock, so this is racey-ish, but good
  	 * enough for our purposes.
  	 */
  	nr_devices = fs_info->fs_devices->open_devices;
  	if (!nr_devices) {
  		smp_mb();
  		nr_devices = fs_info->fs_devices->open_devices;
  		ASSERT(nr_devices);
  		if (!nr_devices) {
  			*free_bytes = 0;
  			return 0;
  		}
  	}
  
  	devices_info = kmalloc_array(nr_devices, sizeof(*devices_info),
  			       GFP_NOFS);
  	if (!devices_info)
  		return -ENOMEM;
  
  	/* calc min stripe number for data space alloction */
  	type = btrfs_get_alloc_profile(root, 1);
  	if (type & BTRFS_BLOCK_GROUP_RAID0) {
  		min_stripes = 2;
  		num_stripes = nr_devices;
  	} else if (type & BTRFS_BLOCK_GROUP_RAID1) {
  		min_stripes = 2;
  		num_stripes = 2;
  	} else if (type & BTRFS_BLOCK_GROUP_RAID10) {
  		min_stripes = 4;
  		num_stripes = 4;
  	}
  
  	if (type & BTRFS_BLOCK_GROUP_DUP)
  		min_stripe_size = 2 * BTRFS_STRIPE_LEN;
  	else
  		min_stripe_size = BTRFS_STRIPE_LEN;
  
  	if (fs_info->alloc_start)
  		mutex_lock(&fs_devices->device_list_mutex);
  	rcu_read_lock();
  	list_for_each_entry_rcu(device, &fs_devices->devices, dev_list) {
  		if (!device->in_fs_metadata || !device->bdev ||
  		    device->is_tgtdev_for_dev_replace)
  			continue;
  
  		if (i >= nr_devices)
  			break;
  
  		avail_space = device->total_bytes - device->bytes_used;
  
  		/* align with stripe_len */
  		avail_space = div_u64(avail_space, BTRFS_STRIPE_LEN);
  		avail_space *= BTRFS_STRIPE_LEN;
  
  		/*
  		 * In order to avoid overwritting the superblock on the drive,
  		 * btrfs starts at an offset of at least 1MB when doing chunk
  		 * allocation.
  		 */
  		skip_space = 1024 * 1024;
  
  		/* user can set the offset in fs_info->alloc_start. */
  		if (fs_info->alloc_start &&
  		    fs_info->alloc_start + BTRFS_STRIPE_LEN <=
  		    device->total_bytes) {
  			rcu_read_unlock();
  			skip_space = max(fs_info->alloc_start, skip_space);
  
  			/*
  			 * btrfs can not use the free space in
  			 * [0, skip_space - 1], we must subtract it from the
  			 * total. In order to implement it, we account the used
  			 * space in this range first.
  			 */
  			ret = btrfs_account_dev_extents_size(device, 0,
  							     skip_space - 1,
  							     &used_space);
  			if (ret) {
  				kfree(devices_info);
  				mutex_unlock(&fs_devices->device_list_mutex);
  				return ret;
  			}
  
  			rcu_read_lock();
  
  			/* calc the free space in [0, skip_space - 1] */
  			skip_space -= used_space;
  		}
  
  		/*
  		 * we can use the free space in [0, skip_space - 1], subtract
  		 * it from the total.
  		 */
  		if (avail_space && avail_space >= skip_space)
  			avail_space -= skip_space;
  		else
  			avail_space = 0;
  
  		if (avail_space < min_stripe_size)
  			continue;
  
  		devices_info[i].dev = device;
  		devices_info[i].max_avail = avail_space;
  
  		i++;
  	}
  	rcu_read_unlock();
  	if (fs_info->alloc_start)
  		mutex_unlock(&fs_devices->device_list_mutex);
  
  	nr_devices = i;
  
  	btrfs_descending_sort_devices(devices_info, nr_devices);
  
  	i = nr_devices - 1;
  	avail_space = 0;
  	while (nr_devices >= min_stripes) {
  		if (num_stripes > nr_devices)
  			num_stripes = nr_devices;
  
  		if (devices_info[i].max_avail >= min_stripe_size) {
  			int j;
  			u64 alloc_size;
  
  			avail_space += devices_info[i].max_avail * num_stripes;
  			alloc_size = devices_info[i].max_avail;
  			for (j = i + 1 - num_stripes; j <= i; j++)
  				devices_info[j].max_avail -= alloc_size;
  		}
  		i--;
  		nr_devices--;
  	}
  
  	kfree(devices_info);
  	*free_bytes = avail_space;
  	return 0;
  }
  
  /*
   * Calculate numbers for 'df', pessimistic in case of mixed raid profiles.
   *
   * If there's a redundant raid level at DATA block groups, use the respective
   * multiplier to scale the sizes.
   *
   * Unused device space usage is based on simulating the chunk allocator
   * algorithm that respects the device sizes, order of allocations and the
   * 'alloc_start' value, this is a close approximation of the actual use but
   * there are other factors that may change the result (like a new metadata
   * chunk).
   *
   * FIXME: not accurate for mixed block groups, total and free/used are ok,
   * available appears slightly larger.
   */
  static int btrfs_statfs(struct dentry *dentry, struct kstatfs *buf)
  {
  	struct btrfs_fs_info *fs_info = btrfs_sb(dentry->d_sb);
  	struct btrfs_super_block *disk_super = fs_info->super_copy;
  	struct list_head *head = &fs_info->space_info;
  	struct btrfs_space_info *found;
  	u64 total_used = 0;
  	u64 total_free_data = 0;
  	int bits = dentry->d_sb->s_blocksize_bits;
  	__be32 *fsid = (__be32 *)fs_info->fsid;
  	unsigned factor = 1;
  	struct btrfs_block_rsv *block_rsv = &fs_info->global_block_rsv;
  	int ret;
  
  	/*
  	 * holding chunk_muext to avoid allocating new chunks, holding
  	 * device_list_mutex to avoid the device being removed
  	 */
  	rcu_read_lock();
  	list_for_each_entry_rcu(found, head, list) {
  		if (found->flags & BTRFS_BLOCK_GROUP_DATA) {
  			int i;
  
  			total_free_data += found->disk_total - found->disk_used;
  			total_free_data -=
  				btrfs_account_ro_block_groups_free_space(found);
  
  			for (i = 0; i < BTRFS_NR_RAID_TYPES; i++) {
  				if (!list_empty(&found->block_groups[i])) {
  					switch (i) {
  					case BTRFS_RAID_DUP:
  					case BTRFS_RAID_RAID1:
  					case BTRFS_RAID_RAID10:
  						factor = 2;
  					}
  				}
  			}
  		}
  
  		total_used += found->disk_used;
  	}
  
  	rcu_read_unlock();
  
  	buf->f_blocks = div_u64(btrfs_super_total_bytes(disk_super), factor);
  	buf->f_blocks >>= bits;
  	buf->f_bfree = buf->f_blocks - (div_u64(total_used, factor) >> bits);
  
  	/* Account global block reserve as used, it's in logical size already */
  	spin_lock(&block_rsv->lock);
  	buf->f_bfree -= block_rsv->size >> bits;
  	spin_unlock(&block_rsv->lock);
  
  	buf->f_bavail = div_u64(total_free_data, factor);
  	ret = btrfs_calc_avail_data_space(fs_info->tree_root, &total_free_data);
  	if (ret)
  		return ret;
  	buf->f_bavail += div_u64(total_free_data, factor);
  	buf->f_bavail = buf->f_bavail >> bits;
  
  	buf->f_type = BTRFS_SUPER_MAGIC;
  	buf->f_bsize = dentry->d_sb->s_blocksize;
  	buf->f_namelen = BTRFS_NAME_LEN;
  
  	/* We treat it as constant endianness (it doesn't matter _which_)
  	   because we want the fsid to come out the same whether mounted
  	   on a big-endian or little-endian host */
  	buf->f_fsid.val[0] = be32_to_cpu(fsid[0]) ^ be32_to_cpu(fsid[2]);
  	buf->f_fsid.val[1] = be32_to_cpu(fsid[1]) ^ be32_to_cpu(fsid[3]);
  	/* Mask in the root object ID too, to disambiguate subvols */
  	buf->f_fsid.val[0] ^= BTRFS_I(d_inode(dentry))->root->objectid >> 32;
  	buf->f_fsid.val[1] ^= BTRFS_I(d_inode(dentry))->root->objectid;
  
  	return 0;
  }
  
  static void btrfs_kill_super(struct super_block *sb)
  {
  	struct btrfs_fs_info *fs_info = btrfs_sb(sb);
  	kill_anon_super(sb);
  	free_fs_info(fs_info);
  }
  
  static struct file_system_type btrfs_fs_type = {
  	.owner		= THIS_MODULE,
  	.name		= "btrfs",
  	.mount		= btrfs_mount,
  	.kill_sb	= btrfs_kill_super,
  	.fs_flags	= FS_REQUIRES_DEV | FS_BINARY_MOUNTDATA,
  };
  MODULE_ALIAS_FS("btrfs");
  
  static int btrfs_control_open(struct inode *inode, struct file *file)
  {
  	/*
  	 * The control file's private_data is used to hold the
  	 * transaction when it is started and is used to keep
  	 * track of whether a transaction is already in progress.
  	 */
  	file->private_data = NULL;
  	return 0;
  }
  
  /*
   * used by btrfsctl to scan devices when no FS is mounted
   */
  static long btrfs_control_ioctl(struct file *file, unsigned int cmd,
  				unsigned long arg)
  {
  	struct btrfs_ioctl_vol_args *vol;
  	struct btrfs_fs_devices *fs_devices;
  	int ret = -ENOTTY;
  
  	if (!capable(CAP_SYS_ADMIN))
  		return -EPERM;
  
  	vol = memdup_user((void __user *)arg, sizeof(*vol));
  	if (IS_ERR(vol))
  		return PTR_ERR(vol);
  
  	switch (cmd) {
  	case BTRFS_IOC_SCAN_DEV:
  		ret = btrfs_scan_one_device(vol->name, FMODE_READ,
  					    &btrfs_fs_type, &fs_devices);
  		break;
  	case BTRFS_IOC_DEVICES_READY:
  		ret = btrfs_scan_one_device(vol->name, FMODE_READ,
  					    &btrfs_fs_type, &fs_devices);
  		if (ret)
  			break;
  		ret = !(fs_devices->num_devices == fs_devices->total_devices);
  		break;
  	}
  
  	kfree(vol);
  	return ret;
  }
  
  static int btrfs_freeze(struct super_block *sb)
  {
  	struct btrfs_trans_handle *trans;
  	struct btrfs_root *root = btrfs_sb(sb)->tree_root;
  
  	trans = btrfs_attach_transaction_barrier(root);
  	if (IS_ERR(trans)) {
  		/* no transaction, don't bother */
  		if (PTR_ERR(trans) == -ENOENT)
  			return 0;
  		return PTR_ERR(trans);
  	}
  	return btrfs_commit_transaction(trans, root);
  }
  
  static int btrfs_show_devname(struct seq_file *m, struct dentry *root)
  {
  	struct btrfs_fs_info *fs_info = btrfs_sb(root->d_sb);
  	struct btrfs_fs_devices *cur_devices;
  	struct btrfs_device *dev, *first_dev = NULL;
  	struct list_head *head;
  	struct rcu_string *name;
  
  	mutex_lock(&fs_info->fs_devices->device_list_mutex);
  	cur_devices = fs_info->fs_devices;
  	while (cur_devices) {
  		head = &cur_devices->devices;
  		list_for_each_entry(dev, head, dev_list) {
  			if (dev->missing)
  				continue;
  			if (!dev->name)
  				continue;
  			if (!first_dev || dev->devid < first_dev->devid)
  				first_dev = dev;
  		}
  		cur_devices = cur_devices->seed;
  	}
  
  	if (first_dev) {
  		rcu_read_lock();
  		name = rcu_dereference(first_dev->name);
  		seq_escape(m, name->str, " \t\n\\");
  		rcu_read_unlock();
  	} else {
  		WARN_ON(1);
  	}
  	mutex_unlock(&fs_info->fs_devices->device_list_mutex);
  	return 0;
  }
  
  static const struct super_operations btrfs_super_ops = {
  	.drop_inode	= btrfs_drop_inode,
  	.evict_inode	= btrfs_evict_inode,
  	.put_super	= btrfs_put_super,
  	.sync_fs	= btrfs_sync_fs,
  	.show_options	= btrfs_show_options,
  	.show_devname	= btrfs_show_devname,
  	.write_inode	= btrfs_write_inode,
  	.alloc_inode	= btrfs_alloc_inode,
  	.destroy_inode	= btrfs_destroy_inode,
  	.statfs		= btrfs_statfs,
  	.remount_fs	= btrfs_remount,
  	.freeze_fs	= btrfs_freeze,
  };
  
  static const struct file_operations btrfs_ctl_fops = {
  	.open = btrfs_control_open,
  	.unlocked_ioctl	 = btrfs_control_ioctl,
  	.compat_ioctl = btrfs_control_ioctl,
  	.owner	 = THIS_MODULE,
  	.llseek = noop_llseek,
  };
  
  static struct miscdevice btrfs_misc = {
  	.minor		= BTRFS_MINOR,
  	.name		= "btrfs-control",
  	.fops		= &btrfs_ctl_fops
  };
  
  MODULE_ALIAS_MISCDEV(BTRFS_MINOR);
  MODULE_ALIAS("devname:btrfs-control");
  
  static int btrfs_interface_init(void)
  {
  	return misc_register(&btrfs_misc);
  }
  
  static void btrfs_interface_exit(void)
  {
  	if (misc_deregister(&btrfs_misc) < 0)
  		printk(KERN_INFO "BTRFS: misc_deregister failed for control device\n");
  }
  
  static void btrfs_print_info(void)
  {
  	printk(KERN_INFO "Btrfs loaded"
  #ifdef CONFIG_BTRFS_DEBUG
  			", debug=on"
  #endif
  #ifdef CONFIG_BTRFS_ASSERT
  			", assert=on"
  #endif
  #ifdef CONFIG_BTRFS_FS_CHECK_INTEGRITY
  			", integrity-checker=on"
  #endif
  			"\n");
  }
  
  static int btrfs_run_sanity_tests(void)
  {
  	int ret;
  
  	ret = btrfs_init_test_fs();
  	if (ret)
  		return ret;
  
  	ret = btrfs_test_free_space_cache();
  	if (ret)
  		goto out;
  	ret = btrfs_test_extent_buffer_operations();
  	if (ret)
  		goto out;
  	ret = btrfs_test_extent_io();
  	if (ret)
  		goto out;
  	ret = btrfs_test_inodes();
  	if (ret)
  		goto out;
  	ret = btrfs_test_qgroups();
  out:
  	btrfs_destroy_test_fs();
  	return ret;
  }
  
  static int __init init_btrfs_fs(void)
  {
  	int err;
  
  	err = btrfs_hash_init();
  	if (err)
  		return err;
  
  	btrfs_props_init();
  
  	err = btrfs_init_sysfs();
  	if (err)
  		goto free_hash;
  
  	btrfs_init_compress();
  
  	err = btrfs_init_cachep();
  	if (err)
  		goto free_compress;
  
  	err = extent_io_init();
  	if (err)
  		goto free_cachep;
  
  	err = extent_map_init();
  	if (err)
  		goto free_extent_io;
  
  	err = ordered_data_init();
  	if (err)
  		goto free_extent_map;
  
  	err = btrfs_delayed_inode_init();
  	if (err)
  		goto free_ordered_data;
  
  	err = btrfs_auto_defrag_init();
  	if (err)
  		goto free_delayed_inode;
  
  	err = btrfs_delayed_ref_init();
  	if (err)
  		goto free_auto_defrag;
  
  	err = btrfs_prelim_ref_init();
  	if (err)
  		goto free_delayed_ref;
  
  	err = btrfs_end_io_wq_init();
  	if (err)
  		goto free_prelim_ref;
  
  	err = btrfs_interface_init();
  	if (err)
  		goto free_end_io_wq;
  
  	btrfs_init_lockdep();
  
  	btrfs_print_info();
  
  	err = btrfs_run_sanity_tests();
  	if (err)
  		goto unregister_ioctl;
  
  	err = register_filesystem(&btrfs_fs_type);
  	if (err)
  		goto unregister_ioctl;
  
  	return 0;
  
  unregister_ioctl:
  	btrfs_interface_exit();
  free_end_io_wq:
  	btrfs_end_io_wq_exit();
  free_prelim_ref:
  	btrfs_prelim_ref_exit();
  free_delayed_ref:
  	btrfs_delayed_ref_exit();
  free_auto_defrag:
  	btrfs_auto_defrag_exit();
  free_delayed_inode:
  	btrfs_delayed_inode_exit();
  free_ordered_data:
  	ordered_data_exit();
  free_extent_map:
  	extent_map_exit();
  free_extent_io:
  	extent_io_exit();
  free_cachep:
  	btrfs_destroy_cachep();
  free_compress:
  	btrfs_exit_compress();
  	btrfs_exit_sysfs();
  free_hash:
  	btrfs_hash_exit();
  	return err;
  }
  
  static void __exit exit_btrfs_fs(void)
  {
  	btrfs_destroy_cachep();
  	btrfs_delayed_ref_exit();
  	btrfs_auto_defrag_exit();
  	btrfs_delayed_inode_exit();
  	btrfs_prelim_ref_exit();
  	ordered_data_exit();
  	extent_map_exit();
  	extent_io_exit();
  	btrfs_interface_exit();
  	btrfs_end_io_wq_exit();
  	unregister_filesystem(&btrfs_fs_type);
  	btrfs_exit_sysfs();
  	btrfs_cleanup_fs_uuids();
  	btrfs_exit_compress();
  	btrfs_hash_exit();
  }
  
  late_initcall(init_btrfs_fs);
  module_exit(exit_btrfs_fs)
  
  MODULE_LICENSE("GPL");
  