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>

diff --git a/block/blk-lib.c b/block/blk-lib.c
index ed89c8f4b2a0497af0e45f075e4781dbb5cf87d2..f8c82a9b401222c84d5d014ac339439a1708caba 100644 (file)
--- 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);