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Commit e950fdf7 authored by Christoph Hellwig's avatar Christoph Hellwig Committed by Jens Axboe
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block: introduce BLKDEV_DISCARD_ZERO to fix zeroout 



Currently blkdev_issue_zeroout cascades down from discards (if the driver
guarantees that discards zero data), to WRITE SAME and then to a loop
writing zeroes.  Unfortunately we ignore run-time EOPNOTSUPP errors in the
block layer blkdev_issue_discard helper to work around DM volumes that
may have mixed discard support underneath.

This patch intoroduces a new BLKDEV_DISCARD_ZERO flag to
blkdev_issue_discard that indicates we are called for zeroing operation.
This allows both to ignore the EOPNOTSUPP hack and actually consolidating
the discard_zeroes_data check into the function.

Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarMartin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: default avatarJens Axboe <axboe@fb.com>
parent b09dcf58

block/blk-lib.c

+11 −6
Original line number Diff line number Diff line
@@ -36,12 +36,17 @@ int __blkdev_issue_discard(struct block_device *bdev, sector_t sector, 
		return -ENXIO;



	if (flags & BLKDEV_DISCARD_SECURE) {

		if (flags & BLKDEV_DISCARD_ZERO)

			return -EOPNOTSUPP;

		if (!blk_queue_secure_erase(q))

			return -EOPNOTSUPP;

		op = REQ_OP_SECURE_ERASE;

	} else {

		if (!blk_queue_discard(q))

			return -EOPNOTSUPP;

		if ((flags & BLKDEV_DISCARD_ZERO) &&

		    !q->limits.discard_zeroes_data)

			return -EOPNOTSUPP;

		op = REQ_OP_DISCARD;

	}
@@ -116,7 +121,7 @@ int blkdev_issue_discard(struct block_device *bdev, sector_t sector, 
			&bio);

	if (!ret && bio) {

		ret = submit_bio_wait(bio);

		if (ret == -EOPNOTSUPP)

		if (ret == -EOPNOTSUPP && !(flags & BLKDEV_DISCARD_ZERO))

			ret = 0;

	}

	blk_finish_plug(&plug);
@@ -241,11 +246,11 @@ static int __blkdev_issue_zeroout(struct block_device *bdev, sector_t sector, 
int blkdev_issue_zeroout(struct block_device *bdev, sector_t sector,

			 sector_t nr_sects, gfp_t gfp_mask, bool discard)

{

	struct request_queue *q = bdev_get_queue(bdev);



	if (discard && blk_queue_discard(q) && q->limits.discard_zeroes_data &&

	    blkdev_issue_discard(bdev, sector, nr_sects, gfp_mask, 0) == 0)

	if (discard) {

		if (!blkdev_issue_discard(bdev, sector, nr_sects, gfp_mask,

				BLKDEV_DISCARD_ZERO))

			return 0;

	}



	if (bdev_write_same(bdev) &&

	    blkdev_issue_write_same(bdev, sector, nr_sects, gfp_mask,

include/linux/blkdev.h

+3 −1
Original line number Diff line number Diff line
@@ -1137,7 +1137,9 @@ static inline struct request *blk_map_queue_find_tag(struct blk_queue_tag *bqt, 
	return bqt->tag_index[tag];

}



#define BLKDEV_DISCARD_SECURE  0x01    /* secure discard */



#define BLKDEV_DISCARD_SECURE	(1 << 0)	/* issue a secure erase */

#define BLKDEV_DISCARD_ZERO	(1 << 1)	/* must reliably zero data */



extern int blkdev_issue_flush(struct block_device *, gfp_t, sector_t *);

extern int blkdev_issue_discard(struct block_device *bdev, sector_t sector,