nilfs2: fix issue with counting number of bio requests for BIO_EOPNOTSUPP error detection

Fix the issue with improper counting number of flying bio requests for
BIO_EOPNOTSUPP error detection case.

The sb_nbio must be incremented exactly the same number of times as
complete() function was called (or will be called) because
nilfs_segbuf_wait() will call wail_for_completion() for the number of
times set to sb_nbio:

  do {
      wait_for_completion(&segbuf->sb_bio_event);
  } while (--segbuf->sb_nbio > 0);

Two functions complete() and wait_for_completion() must be called the
same number of times for the same sb_bio_event.  Otherwise,
wait_for_completion() will hang or leak.

Signed-off-by: Vyacheslav Dubeyko <slava@dubeyko.com>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Acked-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Tested-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/fs/nilfs2/segbuf.c b/fs/nilfs2/segbuf.c
index 5bacf46dc4b3d33cb1854ebf312670966c77e243..2d8be51f90dc9257bf74cad77b719d17f781c739 100644 (file)
--- a/fs/nilfs2/segbuf.c
+++ b/fs/nilfs2/segbuf.c
@@ -376,12 +376,12 @@ static int nilfs_segbuf_submit_bio(struct nilfs_segment_buffer *segbuf,
        bio->bi_private = segbuf;
        bio_get(bio);
        submit_bio(mode, bio);
+       segbuf->sb_nbio++;
        if (bio_flagged(bio, BIO_EOPNOTSUPP)) {
                bio_put(bio);
                err = -EOPNOTSUPP;
                goto failed;
        }
-       segbuf->sb_nbio++;
        bio_put(bio);
 
        wi->bio = NULL;