text: // SPDX-License-Identifier: GPL-2.0
  #include <linux/ceph/ceph_debug.h>
  
  #include <linux/file.h>
  #include <linux/namei.h>
  #include <linux/random.h>
  
  #include "super.h"
  #include "mds_client.h"
  #include <linux/ceph/pagelist.h>
  
  static u64 lock_secret;
  static int ceph_lock_wait_for_completion(struct ceph_mds_client *mdsc,
                                           struct ceph_mds_request *req);
  
  static inline u64 secure_addr(void *addr)
  {
  	u64 v = lock_secret ^ (u64)(unsigned long)addr;
  	/*
  	 * Set the most significant bit, so that MDS knows the 'owner'
  	 * is sufficient to identify the owner of lock. (old code uses
  	 * both 'owner' and 'pid')
  	 */
  	v |= (1ULL << 63);
  	return v;
  }
  
  void __init ceph_flock_init(void)
  {
  	get_random_bytes(&lock_secret, sizeof(lock_secret));
  }
  
  static void ceph_fl_copy_lock(struct file_lock *dst, struct file_lock *src)
  {
  	struct ceph_file_info *fi = dst->fl_file->private_data;
  	struct inode *inode = file_inode(dst->fl_file);
  	atomic_inc(&ceph_inode(inode)->i_filelock_ref);
  	atomic_inc(&fi->num_locks);
  }
  
  static void ceph_fl_release_lock(struct file_lock *fl)
  {
  	struct ceph_file_info *fi = fl->fl_file->private_data;
  	struct inode *inode = file_inode(fl->fl_file);
  	struct ceph_inode_info *ci = ceph_inode(inode);
  	atomic_dec(&fi->num_locks);
  	if (atomic_dec_and_test(&ci->i_filelock_ref)) {
  		/* clear error when all locks are released */
  		spin_lock(&ci->i_ceph_lock);
  		ci->i_ceph_flags &= ~CEPH_I_ERROR_FILELOCK;
  		spin_unlock(&ci->i_ceph_lock);
  	}
  }
  
  static const struct file_lock_operations ceph_fl_lock_ops = {
  	.fl_copy_lock = ceph_fl_copy_lock,
  	.fl_release_private = ceph_fl_release_lock,
  };
  
  /*
   * Implement fcntl and flock locking functions.
   */
  static int ceph_lock_message(u8 lock_type, u16 operation, struct inode *inode,
  			     int cmd, u8 wait, struct file_lock *fl)
  {
  	struct ceph_mds_client *mdsc = ceph_sb_to_mdsc(inode->i_sb);
  	struct ceph_mds_request *req;
  	int err;
  	u64 length = 0;
  	u64 owner;
  
  	if (operation == CEPH_MDS_OP_SETFILELOCK) {
  		/*
  		 * increasing i_filelock_ref closes race window between
  		 * handling request reply and adding file_lock struct to
  		 * inode. Otherwise, auth caps may get trimmed in the
  		 * window. Caller function will decrease the counter.
  		 */
  		fl->fl_ops = &ceph_fl_lock_ops;
  		fl->fl_ops->fl_copy_lock(fl, NULL);
  	}
  
  	if (operation != CEPH_MDS_OP_SETFILELOCK || cmd == CEPH_LOCK_UNLOCK)
  		wait = 0;
  
  	req = ceph_mdsc_create_request(mdsc, operation, USE_AUTH_MDS);
  	if (IS_ERR(req))
  		return PTR_ERR(req);
  	req->r_inode = inode;
  	ihold(inode);
  	req->r_num_caps = 1;
  
  	/* mds requires start and length rather than start and end */
  	if (LLONG_MAX == fl->fl_end)
  		length = 0;
  	else
  		length = fl->fl_end - fl->fl_start + 1;
  
  	owner = secure_addr(fl->fl_owner);
  
  	dout("ceph_lock_message: rule: %d, op: %d, owner: %llx, pid: %llu, "
  	     "start: %llu, length: %llu, wait: %d, type: %d\n", (int)lock_type,
  	     (int)operation, owner, (u64)fl->fl_pid, fl->fl_start, length,
  	     wait, fl->fl_type);
  
  	req->r_args.filelock_change.rule = lock_type;
  	req->r_args.filelock_change.type = cmd;
  	req->r_args.filelock_change.owner = cpu_to_le64(owner);
  	req->r_args.filelock_change.pid = cpu_to_le64((u64)fl->fl_pid);
  	req->r_args.filelock_change.start = cpu_to_le64(fl->fl_start);
  	req->r_args.filelock_change.length = cpu_to_le64(length);
  	req->r_args.filelock_change.wait = wait;
  
  	if (wait)
  		req->r_wait_for_completion = ceph_lock_wait_for_completion;
  
  	err = ceph_mdsc_do_request(mdsc, inode, req);
  	if (!err && operation == CEPH_MDS_OP_GETFILELOCK) {
  		fl->fl_pid = -le64_to_cpu(req->r_reply_info.filelock_reply->pid);
  		if (CEPH_LOCK_SHARED == req->r_reply_info.filelock_reply->type)
  			fl->fl_type = F_RDLCK;
  		else if (CEPH_LOCK_EXCL == req->r_reply_info.filelock_reply->type)
  			fl->fl_type = F_WRLCK;
  		else
  			fl->fl_type = F_UNLCK;
  
  		fl->fl_start = le64_to_cpu(req->r_reply_info.filelock_reply->start);
  		length = le64_to_cpu(req->r_reply_info.filelock_reply->start) +
  						 le64_to_cpu(req->r_reply_info.filelock_reply->length);
  		if (length >= 1)
  			fl->fl_end = length -1;
  		else
  			fl->fl_end = 0;
  
  	}
  	ceph_mdsc_put_request(req);
  	dout("ceph_lock_message: rule: %d, op: %d, pid: %llu, start: %llu, "
  	     "length: %llu, wait: %d, type: %d, err code %d\n", (int)lock_type,
  	     (int)operation, (u64)fl->fl_pid, fl->fl_start,
  	     length, wait, fl->fl_type, err);
  	return err;
  }
  
  static int ceph_lock_wait_for_completion(struct ceph_mds_client *mdsc,
                                           struct ceph_mds_request *req)
  {
  	struct ceph_mds_request *intr_req;
  	struct inode *inode = req->r_inode;
  	int err, lock_type;
  
  	BUG_ON(req->r_op != CEPH_MDS_OP_SETFILELOCK);
  	if (req->r_args.filelock_change.rule == CEPH_LOCK_FCNTL)
  		lock_type = CEPH_LOCK_FCNTL_INTR;
  	else if (req->r_args.filelock_change.rule == CEPH_LOCK_FLOCK)
  		lock_type = CEPH_LOCK_FLOCK_INTR;
  	else
  		BUG_ON(1);
  	BUG_ON(req->r_args.filelock_change.type == CEPH_LOCK_UNLOCK);
  
  	err = wait_for_completion_interruptible(&req->r_completion);
  	if (!err)
  		return 0;
  
  	dout("ceph_lock_wait_for_completion: request %llu was interrupted\n",
  	     req->r_tid);
  
  	mutex_lock(&mdsc->mutex);
  	if (test_bit(CEPH_MDS_R_GOT_RESULT, &req->r_req_flags)) {
  		err = 0;
  	} else {
  		/*
  		 * ensure we aren't running concurrently with
  		 * ceph_fill_trace or ceph_readdir_prepopulate, which
  		 * rely on locks (dir mutex) held by our caller.
  		 */
  		mutex_lock(&req->r_fill_mutex);
  		req->r_err = err;
  		set_bit(CEPH_MDS_R_ABORTED, &req->r_req_flags);
  		mutex_unlock(&req->r_fill_mutex);
  
  		if (!req->r_session) {
  			// haven't sent the request
  			err = 0;
  		}
  	}
  	mutex_unlock(&mdsc->mutex);
  	if (!err)
  		return 0;
  
  	intr_req = ceph_mdsc_create_request(mdsc, CEPH_MDS_OP_SETFILELOCK,
  					    USE_AUTH_MDS);
  	if (IS_ERR(intr_req))
  		return PTR_ERR(intr_req);
  
  	intr_req->r_inode = inode;
  	ihold(inode);
  	intr_req->r_num_caps = 1;
  
  	intr_req->r_args.filelock_change = req->r_args.filelock_change;
  	intr_req->r_args.filelock_change.rule = lock_type;
  	intr_req->r_args.filelock_change.type = CEPH_LOCK_UNLOCK;
  
  	err = ceph_mdsc_do_request(mdsc, inode, intr_req);
  	ceph_mdsc_put_request(intr_req);
  
  	if (err && err != -ERESTARTSYS)
  		return err;
  
  	wait_for_completion_killable(&req->r_safe_completion);
  	return 0;
  }
  
  static int try_unlock_file(struct file *file, struct file_lock *fl)
  {
  	int err;
  	unsigned int orig_flags = fl->fl_flags;
  	fl->fl_flags |= FL_EXISTS;
  	err = locks_lock_file_wait(file, fl);
  	fl->fl_flags = orig_flags;
  	if (err == -ENOENT) {
  		if (!(orig_flags & FL_EXISTS))
  			err = 0;
  		return err;
  	}
  	return 1;
  }
  
  /*
   * Attempt to set an fcntl lock.
   * For now, this just goes away to the server. Later it may be more awesome.
   */
  int ceph_lock(struct file *file, int cmd, struct file_lock *fl)
  {
  	struct inode *inode = file_inode(file);
  	struct ceph_inode_info *ci = ceph_inode(inode);
  	int err = 0;
  	u16 op = CEPH_MDS_OP_SETFILELOCK;
  	u8 wait = 0;
  	u8 lock_cmd;
  
  	if (!(fl->fl_flags & FL_POSIX))
  		return -ENOLCK;
  
  	if (ceph_inode_is_shutdown(inode))
  		return -ESTALE;
  
  	dout("ceph_lock, fl_owner: %p\n", fl->fl_owner);
  
  	/* set wait bit as appropriate, then make command as Ceph expects it*/
  	if (IS_GETLK(cmd))
  		op = CEPH_MDS_OP_GETFILELOCK;
  	else if (IS_SETLKW(cmd))
  		wait = 1;
  
  	spin_lock(&ci->i_ceph_lock);
  	if (ci->i_ceph_flags & CEPH_I_ERROR_FILELOCK) {
  		err = -EIO;
  	}
  	spin_unlock(&ci->i_ceph_lock);
  	if (err < 0) {
  		if (op == CEPH_MDS_OP_SETFILELOCK && F_UNLCK == fl->fl_type)
  			posix_lock_file(file, fl, NULL);
  		return err;
  	}
  
  	if (F_RDLCK == fl->fl_type)
  		lock_cmd = CEPH_LOCK_SHARED;
  	else if (F_WRLCK == fl->fl_type)
  		lock_cmd = CEPH_LOCK_EXCL;
  	else
  		lock_cmd = CEPH_LOCK_UNLOCK;
  
  	if (op == CEPH_MDS_OP_SETFILELOCK && F_UNLCK == fl->fl_type) {
  		err = try_unlock_file(file, fl);
  		if (err <= 0)
  			return err;
  	}
  
  	err = ceph_lock_message(CEPH_LOCK_FCNTL, op, inode, lock_cmd, wait, fl);
  	if (!err) {
  		if (op == CEPH_MDS_OP_SETFILELOCK && F_UNLCK != fl->fl_type) {
  			dout("mds locked, locking locally\n");
  			err = posix_lock_file(file, fl, NULL);
  			if (err) {
  				/* undo! This should only happen if
  				 * the kernel detects local
  				 * deadlock. */
  				ceph_lock_message(CEPH_LOCK_FCNTL, op, inode,
  						  CEPH_LOCK_UNLOCK, 0, fl);
  				dout("got %d on posix_lock_file, undid lock\n",
  				     err);
  			}
  		}
  	}
  	return err;
  }
  
  int ceph_flock(struct file *file, int cmd, struct file_lock *fl)
  {
  	struct inode *inode = file_inode(file);
  	struct ceph_inode_info *ci = ceph_inode(inode);
  	int err = 0;
  	u8 wait = 0;
  	u8 lock_cmd;
  
  	if (!(fl->fl_flags & FL_FLOCK))
  		return -ENOLCK;
  
  	if (ceph_inode_is_shutdown(inode))
  		return -ESTALE;
  
  	dout("ceph_flock, fl_file: %p\n", fl->fl_file);
  
  	spin_lock(&ci->i_ceph_lock);
  	if (ci->i_ceph_flags & CEPH_I_ERROR_FILELOCK) {
  		err = -EIO;
  	}
  	spin_unlock(&ci->i_ceph_lock);
  	if (err < 0) {
  		if (F_UNLCK == fl->fl_type)
  			locks_lock_file_wait(file, fl);
  		return err;
  	}
  
  	if (IS_SETLKW(cmd))
  		wait = 1;
  
  	if (F_RDLCK == fl->fl_type)
  		lock_cmd = CEPH_LOCK_SHARED;
  	else if (F_WRLCK == fl->fl_type)
  		lock_cmd = CEPH_LOCK_EXCL;
  	else
  		lock_cmd = CEPH_LOCK_UNLOCK;
  
  	if (F_UNLCK == fl->fl_type) {
  		err = try_unlock_file(file, fl);
  		if (err <= 0)
  			return err;
  	}
  
  	err = ceph_lock_message(CEPH_LOCK_FLOCK, CEPH_MDS_OP_SETFILELOCK,
  				inode, lock_cmd, wait, fl);
  	if (!err && F_UNLCK != fl->fl_type) {
  		err = locks_lock_file_wait(file, fl);
  		if (err) {
  			ceph_lock_message(CEPH_LOCK_FLOCK,
  					  CEPH_MDS_OP_SETFILELOCK,
  					  inode, CEPH_LOCK_UNLOCK, 0, fl);
  			dout("got %d on locks_lock_file_wait, undid lock\n", err);
  		}
  	}
  	return err;
  }
  
  /*
   * Fills in the passed counter variables, so you can prepare pagelist metadata
   * before calling ceph_encode_locks.
   */
  void ceph_count_locks(struct inode *inode, int *fcntl_count, int *flock_count)
  {
  	struct file_lock *lock;
  	struct file_lock_context *ctx;
  
  	*fcntl_count = 0;
  	*flock_count = 0;
  
  	ctx = inode->i_flctx;
  	if (ctx) {
  		spin_lock(&ctx->flc_lock);
  		list_for_each_entry(lock, &ctx->flc_posix, fl_list)
  			++(*fcntl_count);
  		list_for_each_entry(lock, &ctx->flc_flock, fl_list)
  			++(*flock_count);
  		spin_unlock(&ctx->flc_lock);
  	}
  	dout("counted %d flock locks and %d fcntl locks\n",
  	     *flock_count, *fcntl_count);
  }
  
  /*
   * Given a pointer to a lock, convert it to a ceph filelock
   */
  static int lock_to_ceph_filelock(struct file_lock *lock,
  				 struct ceph_filelock *cephlock)
  {
  	int err = 0;
  	cephlock->start = cpu_to_le64(lock->fl_start);
  	cephlock->length = cpu_to_le64(lock->fl_end - lock->fl_start + 1);
  	cephlock->client = cpu_to_le64(0);
  	cephlock->pid = cpu_to_le64((u64)lock->fl_pid);
  	cephlock->owner = cpu_to_le64(secure_addr(lock->fl_owner));
  
  	switch (lock->fl_type) {
  	case F_RDLCK:
  		cephlock->type = CEPH_LOCK_SHARED;
  		break;
  	case F_WRLCK:
  		cephlock->type = CEPH_LOCK_EXCL;
  		break;
  	case F_UNLCK:
  		cephlock->type = CEPH_LOCK_UNLOCK;
  		break;
  	default:
  		dout("Have unknown lock type %d\n", lock->fl_type);
  		err = -EINVAL;
  	}
  
  	return err;
  }
  
  /*
   * Encode the flock and fcntl locks for the given inode into the ceph_filelock
   * array. Must be called with inode->i_lock already held.
   * If we encounter more of a specific lock type than expected, return -ENOSPC.
   */
  int ceph_encode_locks_to_buffer(struct inode *inode,
  				struct ceph_filelock *flocks,
  				int num_fcntl_locks, int num_flock_locks)
  {
  	struct file_lock *lock;
  	struct file_lock_context *ctx = inode->i_flctx;
  	int err = 0;
  	int seen_fcntl = 0;
  	int seen_flock = 0;
  	int l = 0;
  
  	dout("encoding %d flock and %d fcntl locks\n", num_flock_locks,
  	     num_fcntl_locks);
  
  	if (!ctx)
  		return 0;
  
  	spin_lock(&ctx->flc_lock);
  	list_for_each_entry(lock, &ctx->flc_posix, fl_list) {
  		++seen_fcntl;
  		if (seen_fcntl > num_fcntl_locks) {
  			err = -ENOSPC;
  			goto fail;
  		}
  		err = lock_to_ceph_filelock(lock, &flocks[l]);
  		if (err)
  			goto fail;
  		++l;
  	}
  	list_for_each_entry(lock, &ctx->flc_flock, fl_list) {
  		++seen_flock;
  		if (seen_flock > num_flock_locks) {
  			err = -ENOSPC;
  			goto fail;
  		}
  		err = lock_to_ceph_filelock(lock, &flocks[l]);
  		if (err)
  			goto fail;
  		++l;
  	}
  fail:
  	spin_unlock(&ctx->flc_lock);
  	return err;
  }
  
  /*
   * Copy the encoded flock and fcntl locks into the pagelist.
   * Format is: #fcntl locks, sequential fcntl locks, #flock locks,
   * sequential flock locks.
   * Returns zero on success.
   */
  int ceph_locks_to_pagelist(struct ceph_filelock *flocks,
  			   struct ceph_pagelist *pagelist,
  			   int num_fcntl_locks, int num_flock_locks)
  {
  	int err = 0;
  	__le32 nlocks;
  
  	nlocks = cpu_to_le32(num_fcntl_locks);
  	err = ceph_pagelist_append(pagelist, &nlocks, sizeof(nlocks));
  	if (err)
  		goto out_fail;
  
  	if (num_fcntl_locks > 0) {
  		err = ceph_pagelist_append(pagelist, flocks,
  					   num_fcntl_locks * sizeof(*flocks));
  		if (err)
  			goto out_fail;
  	}
  
  	nlocks = cpu_to_le32(num_flock_locks);
  	err = ceph_pagelist_append(pagelist, &nlocks, sizeof(nlocks));
  	if (err)
  		goto out_fail;
  
  	if (num_flock_locks > 0) {
  		err = ceph_pagelist_append(pagelist, &flocks[num_fcntl_locks],
  					   num_flock_locks * sizeof(*flocks));
  	}
  out_fail:
  	return err;
  }
  