From ac6889cbb254be1ffea376bea4a96ce9be0e0ed0 Mon Sep 17 00:00:00 2001 From: Chris Mason Date: Fri, 9 Oct 2009 11:29:53 -0400 Subject: [PATCH] Btrfs: fix file clone ioctl for bookend extents The file clone ioctl was incorrectly taking the offset into the extent on disk into account when calculating the length of the cloned extent. The length never changes based on the offset into the physical extent. Test case: fallocate -l 1g image mke2fs image bcp image image2 e2fsck -f image2 (errors on image2) The math bug ends up wrapping the length of the extent, and things go wrong from there. Signed-off-by: Chris Mason --- fs/btrfs/ioctl.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c index e8795becad4c..cdbb054102b9 100644 --- a/fs/btrfs/ioctl.c +++ b/fs/btrfs/ioctl.c @@ -1123,8 +1123,10 @@ 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 > off + len) - datal = off + len - key.offset - datao; + + if (key.offset + datal > off + len) + datal = off + len - key.offset; + /* disko == 0 means it's a hole */ if (!disko) datao = 0; -- 2.20.1