From: Filipe Manana <fdmanana@xxxxxxxx>
This patch has been added to the 3.12 stable tree. If you have any
objections, please let us know.
===============
commit 113e8283869b9855c8b999796aadd506bbac155f upstream.
If we pass a length of 0 to the extent_same ioctl, we end up locking an
extent range with a start offset greater then its end offset (if the
destination file's offset is greater than zero). This results in a warning
from extent_io.c:insert_state through the following call chain:
btrfs_extent_same()
btrfs_double_lock()
lock_extent_range()
lock_extent(inode->io_tree, offset, offset + len - 1)
lock_extent_bits()
__set_extent_bit()
insert_state()
--> WARN_ON(end < start)
This leads to an infinite loop when evicting the inode. This is the same
problem that my previous patch titled
"Btrfs: fix inode eviction infinite loop after cloning into it" addressed
but for the extent_same ioctl instead of the clone ioctl.
Signed-off-by: Filipe Manana <fdmanana@xxxxxxxx>
Reviewed-by: Omar Sandoval <osandov@xxxxxxxxxxx>
Signed-off-by: Chris Mason <clm@xxxxxx>
Signed-off-by: Jiri Slaby <jslaby@xxxxxxx>
---
fs/btrfs/ioctl.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 3cf8a7b671cb..d43cd15c3097 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -2671,6 +2671,9 @@ static int btrfs_extent_same(struct inode *src, u64 loff, u64 len,
if (src == dst)
return -EINVAL;
+ if (len == 0)
+ return 0;
+
btrfs_double_lock(src, loff, dst, dst_loff, len);
ret = extent_same_check_offsets(src, loff, len);
--
2.3.5
--
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