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.
CC: <[email protected]>
Signed-off-by: Filipe Manana <[email protected]>
---
fs/btrfs/ioctl.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 4c32350..09a566a 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -2897,6 +2897,9 @@ 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);
--
2.1.3
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