From: Mikulas Patocka <mpatocka@redhat.com>
Date: Tue, 30 Aug 2016 20:11:53 +0000 (-0400)
Subject: dm log writes: move IO accounting earlier to fix error path
X-Git-Tag: firefly_0821_release~176^2~4^2~28^2~59
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=319930894f3614de9dabd1e4fae34328d4274a6e;p=firefly-linux-kernel-4.4.55.git

dm log writes: move IO accounting earlier to fix error path

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 <mpatocka@redhat.com>
Reviewed-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/drivers/md/dm-log-writes.c b/drivers/md/dm-log-writes.c
index c2f29729dab1..d8956b4a7b09 100644
--- 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_writes_c *lc,
 		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;