block: don't try Write Same from __blkdev_issue_zeroout

Write Same can return an error asynchronously if it turns out the
underlying SCSI device does not support Write Same, which makes a
proper fallback to other methods in __blkdev_issue_zeroout impossible.
Thus only issue a Write Same from blkdev_issue_zeroout an don't try it
at all from __blkdev_issue_zeroout as a non-invasive workaround.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reported-by: Junichi Nomura <j-nomura@ce.jp.nec.com>
Fixes: e73c23ff ("block: add async variant of blkdev_issue_zeroout")
Tested-by: Junichi Nomura <j-nomura@ce.jp.nec.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

diff --git a/block/blk-lib.c b/block/blk-lib.c
index f8c82a9b401222c84d5d014ac339439a1708caba..ed1e78e24db0053e993555e14bf730c1cfb868c2 100644 (file)
--- a/block/blk-lib.c
+++ b/block/blk-lib.c
@@ -306,11 +306,6 @@ int __blkdev_issue_zeroout(struct block_device *bdev, sector_t sector,
        if (ret == 0 || (ret && ret != -EOPNOTSUPP))
                goto out;
 
-       ret = __blkdev_issue_write_same(bdev, sector, nr_sects, gfp_mask,
-                       ZERO_PAGE(0), biop);
-       if (ret == 0 || (ret && ret != -EOPNOTSUPP))
-               goto out;
-
        ret = 0;
        while (nr_sects != 0) {
                bio = next_bio(bio, min(nr_sects, (sector_t)BIO_MAX_PAGES),
@@ -369,6 +364,10 @@ int blkdev_issue_zeroout(struct block_device *bdev, sector_t sector,
                        return 0;
        }
 
+       if (!blkdev_issue_write_same(bdev, sector, nr_sects, gfp_mask,
+                       ZERO_PAGE(0)))
+               return 0;
+
        blk_start_plug(&plug);
        ret = __blkdev_issue_zeroout(bdev, sector, nr_sects, gfp_mask,
                        &bio, discard);