Btrfs: reserve sufficient space for ioctl clone

Fix a crash/BUG_ON in the clone ioctl due to insufficient reservation. We
need to reserve space for:

 - adjusting the old extent (possibly splitting it)
 - adding the new extent
 - updating the inode

Signed-off-by: Sage Weil <sage@newdream.net>
Signed-off-by: Chris Mason <chris.mason@oracle.com>

1 files changed, 6 insertions, 1 deletions

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 9947a0ac7bd5..6f89bcc4e555 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -2336,7 +2336,12 @@ static noinline long btrfs_ioctl_clone(struct file *file, unsigned long srcfd,
                         else
                                 new_key.offset = destoff;
 
-                        trans = btrfs_start_transaction(root, 1);
+                        /*
+                         * 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;