btrfs: fix error handling when submitting direct I/O bio

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>

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 259239b333705220853a10b10009ef99a57b59b9..b628c319a5b65fd75ea2a07a2386602e069ab742 100644 (file)
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -7939,7 +7939,6 @@ static int btrfs_submit_direct_hook(struct btrfs_dio_private *dip)
 
        /* bio split */
        ASSERT(geom.len <= INT_MAX);
-       atomic_inc(&dip->pending_bios);
        do {
                clone_len = min_t(int, submit_len, geom.len);
 
@@ -7989,7 +7988,8 @@ submit:
        if (!status)
                return 0;
 
-       bio_put(bio);
+       if (bio != orig_bio)
+               bio_put(bio);
 out_err:
        dip->errors = 1;
        /*
@@ -8030,7 +8030,7 @@ 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;