1 files changed, 41 insertions, 29 deletions

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 709d9446896a..973236b72a97 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -748,7 +748,6 @@ static int create_snapshot(struct btrfs_root *root, struct inode *dir,
 	struct btrfs_pending_snapshot *pending_snapshot;
 	struct btrfs_trans_handle *trans;
 	int ret;
-	bool snapshot_force_cow = false;
 
 	if (!test_bit(BTRFS_ROOT_SHAREABLE, &root->state))
 		return -EINVAL;
@@ -771,27 +770,6 @@ static int create_snapshot(struct btrfs_root *root, struct inode *dir,
 		goto free_pending;
 	}
 
-	/*
-	 * Force new buffered writes to reserve space even when NOCOW is
-	 * possible. This is to avoid later writeback (running dealloc) to
-	 * fallback to COW mode and unexpectedly fail with ENOSPC.
-	 */
-	btrfs_drew_read_lock(&root->snapshot_lock);
-
-	ret = btrfs_start_delalloc_snapshot(root);
-	if (ret)
-		goto dec_and_free;
-
-	/*
-	 * All previous writes have started writeback in NOCOW mode, so now
-	 * we force future writes to fallback to COW mode during snapshot
-	 * creation.
-	 */
-	atomic_inc(&root->snapshot_force_cow);
-	snapshot_force_cow = true;
-
-	btrfs_wait_ordered_extents(root, U64_MAX, 0, (u64)-1);
-
 	btrfs_init_block_rsv(&pending_snapshot->block_rsv,
 			     BTRFS_BLOCK_RSV_TEMP);
 	/*
@@ -806,7 +784,7 @@ static int create_snapshot(struct btrfs_root *root, struct inode *dir,
 					&pending_snapshot->block_rsv, 8,
 					false);
 	if (ret)
-		goto dec_and_free;
+		goto free_pending;
 
 	pending_snapshot->dentry = dentry;
 	pending_snapshot->root = root;
@@ -848,11 +826,6 @@ static int create_snapshot(struct btrfs_root *root, struct inode *dir,
 fail:
 	btrfs_put_root(pending_snapshot->snap);
 	btrfs_subvolume_release_metadata(fs_info, &pending_snapshot->block_rsv);
-dec_and_free:
-	if (snapshot_force_cow)
-		atomic_dec(&root->snapshot_force_cow);
-	btrfs_drew_read_unlock(&root->snapshot_lock);
-
 free_pending:
 	kfree(pending_snapshot->root_item);
 	btrfs_free_path(pending_snapshot->path);
@@ -983,6 +956,45 @@ out_unlock:
 	return error;
 }
 
+static noinline int btrfs_mksnapshot(const struct path *parent,
+				   const char *name, int namelen,
+				   struct btrfs_root *root,
+				   bool readonly,
+				   struct btrfs_qgroup_inherit *inherit)
+{
+	int ret;
+	bool snapshot_force_cow = false;
+
+	/*
+	 * Force new buffered writes to reserve space even when NOCOW is
+	 * possible. This is to avoid later writeback (running dealloc) to
+	 * fallback to COW mode and unexpectedly fail with ENOSPC.
+	 */
+	btrfs_drew_read_lock(&root->snapshot_lock);
+
+	ret = btrfs_start_delalloc_snapshot(root);
+	if (ret)
+		goto out;
+
+	/*
+	 * All previous writes have started writeback in NOCOW mode, so now
+	 * we force future writes to fallback to COW mode during snapshot
+	 * creation.
+	 */
+	atomic_inc(&root->snapshot_force_cow);
+	snapshot_force_cow = true;
+
+	btrfs_wait_ordered_extents(root, U64_MAX, 0, (u64)-1);
+
+	ret = btrfs_mksubvol(parent, name, namelen,
+			     root, readonly, inherit);
+out:
+	if (snapshot_force_cow)
+		atomic_dec(&root->snapshot_force_cow);
+	btrfs_drew_read_unlock(&root->snapshot_lock);
+	return ret;
+}
+
 /*
  * 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.
@@ -1762,7 +1774,7 @@ static noinline int __btrfs_ioctl_snap_create(struct file *file,
 			 */
 			ret = -EPERM;
 		} else {
-			ret = btrfs_mksubvol(&file->f_path, name, namelen,
+			ret = btrfs_mksnapshot(&file->f_path, name, namelen,
 					     BTRFS_I(src_inode)->root,
 					     readonly, inherit);
 		}