[PATCH 4.4 062/118] dm log writes: move IO accounting earlier to fix error path

[Greg Kroah-Hartman]

4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Mikulas Patocka <mpato...@redhat.com>

commit a5d60783df61fbb67b7596b8a0f6b4b2e05251d5 upstream.

Move log_one_block()'s atomic_inc(&lc->io_blocks) before bio_alloc() to
fix a bug that the target hangs if bio_alloc() fails.  The error path
does put_io_block(lc), so atomic_inc(&lc->io_blocks) must occur before
invoking the error path to avoid underflow of lc->io_blocks.

Signed-off-by: Mikulas Patocka <mpato...@redhat.com>
Reviewed-by: Josef Bacik <jba...@fb.com>
Signed-off-by: Mike Snitzer <snit...@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>

---
 drivers/md/dm-log-writes.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/md/dm-log-writes.c
+++ b/drivers/md/dm-log-writes.c
@@ -258,12 +258,12 @@ static int log_one_block(struct log_writ
                goto out;
        sector++;
 
+       atomic_inc(&lc->io_blocks);
        bio = bio_alloc(GFP_KERNEL, block->vec_cnt);
        if (!bio) {
                DMERR("Couldn't alloc log bio");
                goto error;
        }
-       atomic_inc(&lc->io_blocks);
        bio->bi_iter.bi_size = 0;
        bio->bi_iter.bi_sector = sector;
        bio->bi_bdev = lc->logdev->bdev;