Btrfs: fix arithmetic error in clone ioctl

Fix an arithmetic error that was breaking extents cloned via the clone
ioctl starting in the second half of a file.

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

1 files changed, 1 insertions, 2 deletions

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index a13fd556db74..a8577a7f26ab 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -1105,8 +1105,7 @@ static noinline long btrfs_ioctl_clone(struct file *file, unsigned long srcfd,
                                         datao += off - key.offset;
                                         datal -= off - key.offset;
                                 }
-                                if (key.offset + datao + datal + key.offset >
-                                    off + len)
+                                if (key.offset + datao + datal > off + len)
                                         datal = off + len - key.offset - datao;
                                 /* disko == 0 means it's a hole */
                                 if (!disko)