Thread (2 messages) 2 messages, 2 authors, 2016-06-10

Re: [PATCH V2] block: correctly fallback for zeroout

From: Shaohua Li <hidden>
Date: 2016-06-10 02:55:30
Also in: lkml

Possibly related (same subject, not in this thread)

On Thu, Jun 09, 2016 at 10:04:08PM -0400, Martin K. Petersen wrote:
quoted hunk ↗ jump to hunk
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quoted
quoted
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"Shaohua" == Shaohua Li [off-list ref] writes:
Shaohua,

diff --git a/block/blk-lib.c b/block/blk-lib.c
index 23d7f30..a3a26c8 100644
--- a/block/blk-lib.c
+++ b/block/blk-lib.c
@@ -84,6 +84,28 @@ int __blkdev_issue_discard(struct block_device *bdev, sector_t sector,
 }
 EXPORT_SYMBOL(__blkdev_issue_discard);
 
+static int do_blkdev_issue_discard(struct block_device *bdev, sector_t sector,
+		sector_t nr_sects, gfp_t gfp_mask, unsigned long flags,
+		int *io_err)
+{
+	int type = REQ_WRITE | REQ_DISCARD;
+	struct bio *bio = NULL;
+	struct blk_plug plug;
+	int ret;
+
+	if (flags & BLKDEV_DISCARD_SECURE)
+		type |= REQ_SECURE;
+
+	blk_start_plug(&plug);
+	ret = __blkdev_issue_discard(bdev, sector, nr_sects, gfp_mask, type,
+			&bio);
+	if (!ret && bio)
+		*io_err = submit_bio_wait(type, bio);
+	blk_finish_plug(&plug);
+
+	return ret;
+}
+

What does the extra io_err buy us? Just have this function return an
error. And then in blkdev_issue_discard if you get -EOPNOTSUPP you
special case it there.
The __blkdev_issue_discard returns -EOPNOTSUPP if disk doesn't support discard.
in that case, blkdev_issue_discard doesn't return 0. blkdev_issue_discard only
returns 0 if IO error is -EOPNOTSUPP. Please see bbd848e0fade51ae51da.

Thanks,
Shaohua
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