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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: Dmitry Monakhov <dmonakhov@openvz.org>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
This commit is contained in:
Dmitry Monakhov 2010-04-28 17:55:09 +04:00 committed by Jens Axboe
parent f31e7e4022
commit 3f14d792f9
2 changed files with 120 additions and 1 deletions
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118
block/blk-lib.c
View File

@ -112,3 +112,121 @@ int blkdev_issue_discard(struct block_device *bdev, sector_t sector,
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);

3
include/linux/blkdev.h
View File

@ -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)
{