From: David Sterba <dsterba@suse.cz>
Date: Mon, 1 Aug 2011 18:11:57 +0200
Subject: [PATCH] btrfs: allow cross-subvolume file clone
Reference: bnc#698540
Patch-mainline: pending

Lift the EXDEV condition and allow different root trees for files being
cloned, then pass source inode's root when searching for extents.

Signed-off-by: David Sterba <dsterba@suse.cz>
---
 fs/btrfs/ioctl.c |   11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -2268,6 +2268,10 @@ static noinline long btrfs_ioctl_clone(s
 		goto out_drop_write;
 	}
 
+	ret = -EXDEV;
+	if (src_file->f_path.mnt != file->f_path.mnt)
+		goto out_fput;
+
 	src = src_file->f_dentry->d_inode;
 
 	ret = -EINVAL;
@@ -2288,7 +2292,7 @@ static noinline long btrfs_ioctl_clone(s
 		goto out_fput;
 
 	ret = -EXDEV;
-	if (src->i_sb != inode->i_sb || BTRFS_I(src)->root != root)
+	if (src->i_sb != inode->i_sb)
 		goto out_fput;
 
 	ret = -ENOMEM;
@@ -2362,13 +2366,14 @@ static noinline long btrfs_ioctl_clone(s
 		 * note the key will change type as we walk through the
 		 * tree.
 		 */
-		ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
+		ret = btrfs_search_slot(NULL, BTRFS_I(src)->root, &key, path,
+				0, 0);
 		if (ret < 0)
 			goto out;
 
 		nritems = btrfs_header_nritems(path->nodes[0]);
 		if (path->slots[0] >= nritems) {
-			ret = btrfs_next_leaf(root, path);
+			ret = btrfs_next_leaf(BTRFS_I(src)->root, path);
 			if (ret < 0)
 				goto out;
 			if (ret > 0)