block: don't try to discard from __blkdev_issue_zeroout

Discard can return -EIO asynchronously if the alignment for the request
isn't suitable for the driver, which makes a proper fallback to other
methods in __blkdev_issue_zeroout impossible.  Thus only issue a sync
discard from blkdev_issue_zeroout an don't try discard at all from
__blkdev_issue_zeroout as a non-invasive workaround.

One more reason why abusing discard for zeroing must die..

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reported-by: Eryu Guan <eguan@redhat.com>
Fixes: e73c23ff ("block: add async variant of blkdev_issue_zeroout")
Signed-off-by: Jens Axboe <axboe@fb.com>

1 files changed, 6 insertions, 7 deletions

diff --git a/block/blk-lib.c b/block/blk-lib.c
index ed89c8f4b2a0..f8c82a9b4012 100644
--- a/block/blk-lib.c
+++ b/block/blk-lib.c
@@ -301,13 +301,6 @@ int __blkdev_issue_zeroout(struct block_device *bdev, sector_t sector,
         if ((sector | nr_sects) & bs_mask)
                 return -EINVAL;
 
-        if (discard) {
-                ret = __blkdev_issue_discard(bdev, sector, nr_sects, gfp_mask,
-                                BLKDEV_DISCARD_ZERO, biop);
-                if (ret == 0 || (ret && ret != -EOPNOTSUPP))
-                        goto out;
-        }
-
         ret = __blkdev_issue_write_zeroes(bdev, sector, nr_sects, gfp_mask,
                         biop);
         if (ret == 0 || (ret && ret != -EOPNOTSUPP))
@@ -370,6 +363,12 @@ int blkdev_issue_zeroout(struct block_device *bdev, sector_t sector,
         struct bio *bio = NULL;
         struct blk_plug plug;
 
+        if (discard) {
+                if (!blkdev_issue_discard(bdev, sector, nr_sects, gfp_mask,
+                                BLKDEV_DISCARD_ZERO))
+                        return 0;
+        }
+
         blk_start_plug(&plug);
         ret = __blkdev_issue_zeroout(bdev, sector, nr_sects, gfp_mask,
                         &bio, discard);