btrfs_cmp_data_prepare() (almost) always returns 0 i.e. ignoring errors
from gather_extent_pages(). While the pages are freed by
btrfs_cmp_data_free(), cmp->num_pages still has > 0. Then,
btrfs_extent_same() try to access the already freed pages causing faults
(or violates PageLocked assertion).
This patch just return the error as is so that the caller stop the process.
Signed-off-by: Naohiro Aota <naohiro.aota@xxxxxxx>
Fixes: f441460202cb ("btrfs: fix deadlock with extent-same and readpage")
Cc: <stable@xxxxxxxxxxxxxxx> # 4.2
---
fs/btrfs/ioctl.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index ae8fbf9d3de2..b5971923f15f 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -3028,7 +3028,7 @@ static int btrfs_cmp_data_prepare(struct inode *src, u64 loff,
out:
if (ret)
btrfs_cmp_data_free(cmp);
- return 0;
+ return ret;
}
static int btrfs_cmp_data(u64 len, struct cmp_pages *cmp)
--
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