Commit d5ce4c31 authored by Ilya Dryomov's avatar Ilya Dryomov Committed by Jens Axboe
Browse files

block: cope with WRITE ZEROES failing in blkdev_issue_zeroout() 



sd_config_write_same() ignores ->max_ws_blocks == 0 and resets it to
permit trying WRITE SAME on older SCSI devices, unless ->no_write_same
is set.  Because REQ_OP_WRITE_ZEROES is implemented in terms of WRITE
SAME, blkdev_issue_zeroout() may fail with -EREMOTEIO:

  $ fallocate -zn -l 1k /dev/sdg
  fallocate: fallocate failed: Remote I/O error
  $ fallocate -zn -l 1k /dev/sdg  # OK
  $ fallocate -zn -l 1k /dev/sdg  # OK

The following calls succeed because sd_done() sets ->no_write_same in
response to a sense that would become BLK_STS_TARGET/-EREMOTEIO, causing
__blkdev_issue_zeroout() to fall back to generating ZERO_PAGE bios.

This means blkdev_issue_zeroout() must cope with WRITE ZEROES failing
and fall back to manually zeroing, unless BLKDEV_ZERO_NOFALLBACK is
specified.  For BLKDEV_ZERO_NOFALLBACK case, return -EOPNOTSUPP if
sd_done() has just set ->no_write_same thus indicating lack of offload
support.

Fixes: c20cfc27 ("block: stop using blkdev_issue_write_same for zeroing")
Cc: Hannes Reinecke <hare@suse.com>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarMartin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: default avatarIlya Dryomov <idryomov@gmail.com>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 425a4dba

block/blk-lib.c

+35 −10
Original line number Diff line number Diff line
@@ -321,12 +321,6 @@ static int __blkdev_issue_zero_pages(struct block_device *bdev, 
 *  Zero-fill a block range, either using hardware offload or by explicitly

 *  writing zeroes to the device.

 *

 *  Note that this function may fail with -EOPNOTSUPP if the driver signals

 *  zeroing offload support, but the device fails to process the command (for

 *  some devices there is no non-destructive way to verify whether this

 *  operation is actually supported).  In this case the caller should call

 *  retry the call to blkdev_issue_zeroout() and the fallback path will be used.

 *

 *  If a device is using logical block provisioning, the underlying space will

 *  not be released if %flags contains BLKDEV_ZERO_NOUNMAP.

 *
@@ -370,18 +364,49 @@ EXPORT_SYMBOL(__blkdev_issue_zeroout); 
int blkdev_issue_zeroout(struct block_device *bdev, sector_t sector,

		sector_t nr_sects, gfp_t gfp_mask, unsigned flags)

{

	int ret;

	struct bio *bio = NULL;

	int ret = 0;

	sector_t bs_mask;

	struct bio *bio;

	struct blk_plug plug;

	bool try_write_zeroes = !!bdev_write_zeroes_sectors(bdev);



	bs_mask = (bdev_logical_block_size(bdev) >> 9) - 1;

	if ((sector | nr_sects) & bs_mask)

		return -EINVAL;



retry:

	bio = NULL;

	blk_start_plug(&plug);

	ret = __blkdev_issue_zeroout(bdev, sector, nr_sects, gfp_mask,

			&bio, flags);

	if (try_write_zeroes) {

		ret = __blkdev_issue_write_zeroes(bdev, sector, nr_sects,

						  gfp_mask, &bio, flags);

	} else if (!(flags & BLKDEV_ZERO_NOFALLBACK)) {

		ret = __blkdev_issue_zero_pages(bdev, sector, nr_sects,

						gfp_mask, &bio);

	} else {

		/* No zeroing offload support */

		ret = -EOPNOTSUPP;

	}

	if (ret == 0 && bio) {

		ret = submit_bio_wait(bio);

		bio_put(bio);

	}

	blk_finish_plug(&plug);

	if (ret && try_write_zeroes) {

		if (!(flags & BLKDEV_ZERO_NOFALLBACK)) {

			try_write_zeroes = false;

			goto retry;

		}

		if (!bdev_write_zeroes_sectors(bdev)) {

			/*

			 * Zeroing offload support was indicated, but the

			 * device reported ILLEGAL REQUEST (for some devices

			 * there is no non-destructive way to verify whether

			 * WRITE ZEROES is actually supported).

			 */

			ret = -EOPNOTSUPP;

		}

	}



	return ret;

}

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