[PATCH 4.14 159/190] btrfs: fix error handling when submitting direct I/O bio

Greg Kroah-Hartman
2020-06-19T16:31:53Z

From: Omar Sandoval <osandov@fb.com>

[ Upstream commit 6d3113a193e3385c72240096fe397618ecab6e43 ]

In btrfs_submit_direct_hook(), if a direct I/O write doesn't span a RAID
stripe or chunk, we submit orig_bio without cloning it. In this case, we
don't increment pending_bios. Then, if btrfs_submit_dio_bio() fails, we
decrement pending_bios to -1, and we never complete orig_bio. Fix it by
initializing pending_bios to 1 instead of incrementing later.

Fixing this exposes another bug: we put orig_bio prematurely and then
put it again from end_io. Fix it by not putting orig_bio.

After this change, pending_bios is really more of a reference count, but
I'll leave that cleanup separate to keep the fix small.

Fixes: e65e15355429 ("btrfs: fix panic caused by direct IO")
CC: stable@vger.kernel.org # 4.4+
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
fs/btrfs/inode.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 2a196bb134d9..3e65ac2d4869 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -8707,7 +8707,6 @@ static int btrfs_submit_direct_hook(struct btrfs_dio_private *dip)

/* bio split */
ASSERT(map_length <= INT_MAX);
- atomic_inc(&dip->pending_bios);
do {
clone_len = min_t(int, submit_len, map_length);

@@ -8758,7 +8757,8 @@ static int btrfs_submit_direct_hook(struct btrfs_dio_private *dip)
if (!status)
return 0;

- bio_put(bio);
+ if (bio != orig_bio)
+ bio_put(bio);
out_err:
dip->errors = 1;
/*
@@ -8798,7 +8798,7 @@ static void btrfs_submit_direct(struct bio *dio_bio, struct inode *inode,
bio->bi_private = dip;
dip->orig_bio = bio;
dip->dio_bio = dio_bio;
- atomic_set(&dip->pending_bios, 0);
+ atomic_set(&dip->pending_bios, 1);
io_bio = btrfs_io_bio(bio);
io_bio->logical = file_offset;

--
2.25.1