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Commit 3f14d792 authored by Dmitry Monakhov's avatar Dmitry Monakhov Committed by Jens Axboe
Browse files

blkdev: add blkdev_issue_zeroout helper function 



- Add bio_batch helper primitive. This is rather generic primitive
  for submitting/waiting a complex request which consists of several
  bios.
- blkdev_issue_zeroout() generate number of zero filed write bios.

Signed-off-by: default avatarDmitry Monakhov <dmonakhov@openvz.org>
Signed-off-by: default avatarJens Axboe <jens.axboe@oracle.com>
parent f31e7e40

block/blk-lib.c

+118 −0
Original line number Diff line number Diff line
@@ -112,3 +112,121 @@ out: 
	return -ENOMEM;

}

EXPORT_SYMBOL(blkdev_issue_discard);



struct bio_batch

{

	atomic_t 		done;

	unsigned long 		flags;

	struct completion 	*wait;

	bio_end_io_t		*end_io;

};



static void bio_batch_end_io(struct bio *bio, int err)

{

	struct bio_batch *bb = bio->bi_private;

	if (err) {

		if (err == -EOPNOTSUPP)

			set_bit(BIO_EOPNOTSUPP, &bb->flags);

		else

			clear_bit(BIO_UPTODATE, &bb->flags);

	}

	if (bb) {

		if (bb->end_io)

			bb->end_io(bio, err);

		atomic_inc(&bb->done);

		complete(bb->wait);

	}

	bio_put(bio);

}



/**

 * blkdev_issue_zeroout generate number of zero filed write bios

 * @bdev:	blockdev to issue

 * @sector:	start sector

 * @nr_sects:	number of sectors to write

 * @gfp_mask:	memory allocation flags (for bio_alloc)

 * @flags:	BLKDEV_IFL_* flags to control behaviour

 *

 * Description:

 *  Generate and issue number of bios with zerofiled pages.

 *  Send barrier at the beginning and at the end if requested. This guarantie

 *  correct request ordering. Empty barrier allow us to avoid post queue flush.

 */



int blkdev_issue_zeroout(struct block_device *bdev, sector_t sector,

			sector_t nr_sects, gfp_t gfp_mask, unsigned long flags)

{

	int ret = 0;

	struct bio *bio;

	struct bio_batch bb;

	unsigned int sz, issued = 0;

	DECLARE_COMPLETION_ONSTACK(wait);



	atomic_set(&bb.done, 0);

	bb.flags = 1 << BIO_UPTODATE;

	bb.wait = &wait;

	bb.end_io = NULL;



	if (flags & BLKDEV_IFL_BARRIER) {

		/* issue async barrier before the data */

		ret = blkdev_issue_flush(bdev, gfp_mask, NULL, 0);

		if (ret)

			return ret;

	}

submit:

	while (nr_sects != 0) {

		bio = bio_alloc(gfp_mask,

				min(nr_sects, (sector_t)BIO_MAX_PAGES));

		if (!bio)

			break;



		bio->bi_sector = sector;

		bio->bi_bdev   = bdev;

		bio->bi_end_io = bio_batch_end_io;

		if (flags & BLKDEV_IFL_WAIT)

			bio->bi_private = &bb;



		while(nr_sects != 0) {

			sz = min(PAGE_SIZE >> 9 , nr_sects);

			if (sz == 0)

				/* bio has maximum size possible */

				break;

			ret = bio_add_page(bio, ZERO_PAGE(0), sz << 9, 0);

			nr_sects -= ret >> 9;

			sector += ret >> 9;

			if (ret < (sz << 9))

				break;

		}

		issued++;

		submit_bio(WRITE, bio);

	}

	/*

	 * When all data bios are in flight. Send final barrier if requeted.

	 */

	if (nr_sects == 0 && flags & BLKDEV_IFL_BARRIER)

		ret = blkdev_issue_flush(bdev, gfp_mask, NULL,

					flags & BLKDEV_IFL_WAIT);





	if (flags & BLKDEV_IFL_WAIT)

		/* Wait for bios in-flight */

		while ( issued != atomic_read(&bb.done))

			wait_for_completion(&wait);



	if (!test_bit(BIO_UPTODATE, &bb.flags))

		/* One of bios in the batch was completed with error.*/

		ret = -EIO;



	if (ret)

		goto out;



	if (test_bit(BIO_EOPNOTSUPP, &bb.flags)) {

		ret = -EOPNOTSUPP;

		goto out;

	}

	if (nr_sects != 0)

		goto submit;

out:

	return ret;

}

EXPORT_SYMBOL(blkdev_issue_zeroout);

include/linux/blkdev.h

+2 −1
Original line number Diff line number Diff line
@@ -1008,7 +1008,8 @@ extern int blkdev_issue_flush(struct block_device *, gfp_t, sector_t *, 
			unsigned long);

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

		sector_t nr_sects, gfp_t gfp_mask, unsigned long flags);



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

			sector_t nr_sects, gfp_t gfp_mask, unsigned long flags);

static inline int sb_issue_discard(struct super_block *sb,

				   sector_t block, sector_t nr_blocks)

{