/*
* Functions related to generic helpers functions
*/
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/bio.h>
#include <linux/blkdev.h>
#include <linux/scatterlist.h>
#include "blk.h"
struct bio_batch {
atomic_t done;
int error;
struct completion *wait;
};
static void bio_batch_end_io(struct bio *bio)
{
struct bio_batch *bb = bio->bi_private;
if (bio->bi_error && bio->bi_error != -EOPNOTSUPP)
bb->error = bio->bi_error;
if (atomic_dec_and_test(&bb->done))
complete(bb->wait);
bio_put(bio);
}
/**
* blkdev_issue_discard - queue a discard
* @bdev: blockdev to issue discard for
* @sector: start sector
* @nr_sects: number of sectors to discard
* @gfp_mask: memory allocation flags (for bio_alloc)
* @flags: BLKDEV_IFL_* flags to control behaviour
*
* Description:
* Issue a discard request for the sectors in question.
*/
int blkdev_issue_discard(struct block_device *bdev, sector_t sector,
sector_t nr_sects, gfp_t gfp_mask, unsigned long flags)
{
DECLARE_COMPLETION_ONSTACK(wait);
struct request_queue *q = bdev_get_queue(bdev);
int type = REQ_WRITE | REQ_DISCARD;
unsigned int max_discard_sectors, granularity;
int alignment;
struct bio_batch bb;
struct bio *bio;
int ret = 0;
struct blk_plug plug;
if (!q)
return -ENXIO;
if (!blk_queue_discard(q))
return -EOPNOTSUPP;
/* Zero-sector (unknown) and one-sector granularities are the same. */
granularity = max(q->limits.discard_granularity >> 9, 1U);
alignment = (bdev_discard_alignment(bdev) >> 9) % granularity;
/*
* Ensure that max_discard_sectors is of the proper
* granularity, so that requests stay aligned after a split.
*/
max_discard_sectors = min(q->limits.max_discard_sectors, UINT_MAX >> 9);
max_discard_sectors -= max_discard_sectors % granularity;
if (unlikely(!max_discard_sectors)) {
/* Avoid infinite loop below. Being cautious never hurts. */
return -EOPNOTSUPP;
}
if (flags & BLKDEV_DISCARD_SECURE) {
if (!blk_queue_secdiscard(q))
return -EOPNOTSUPP;
type |= REQ_SECURE;
}
atomic_set(&bb.done, 1);
bb.error = 0;
bb.wait = &wait;
blk_start_plug(&plug);
while (nr_sects) {
unsigned int req_sects;
sector_t end_sect, tmp;
bio = bio_alloc(gfp_mask, 1);
if (!bio) {
ret = -ENOMEM;
break;
}
req_sects = min_t(sector_t, nr_sects, max_discard_sectors);
/*
* If splitting a request, and the next starting sector would be
* misaligned, stop the discard at the previous aligned sector.
*/
end_sect = sector + req_sects;
tmp = end_sect;
if (req_sects < nr_sects &&
sector_div(tmp, granularity) != alignment) {
end_sect = end_sect - alignment;
sector_div(end_sect, granularity);
end_sect = end_sect * granularity + alignment;
req_sects = end_sect - sector;
}
bio->bi_iter.bi_sector = sector;
bio->bi_end_io = bio_batch_end_io;
bio->bi_bdev = bdev;
bio->bi_private = &bb;
bio->bi_iter.bi_size = req_sects << 9;
nr_sects -= req_sects;
sector = end_sect;
atomic_inc(&bb.done);
submit_bio(type, bio);
/*
* We can loop for a long time in here, if someone does
* full device discards (like mkfs). Be nice and allow
* us to schedule out to avoid softlocking if preempt
* is disabled.
*/
cond_resched();
}
blk_finish_plug(&plug);
/* Wait for bios in-flight */
if (!atomic_dec_and_test(&bb.done))
wait_for_completion_io(&wait);
if (bb.error)
return bb.error;
return ret;
}
EXPORT_SYMBOL(blkdev_issue_discard);
/**
* blkdev_issue_write_same - queue a write same operation
* @bdev: target blockdev
* @sector: start sector
* @nr_sects: number of sectors to write
* @gfp_mask: memory allocation flags (for bio_alloc)
* @page: page containing data to write
*
* Description:
* Issue a write same request for the sectors in question.
*/
int blkdev_issue_write_same(struct block_device *bdev, sector_t sector,
sector_t nr_sects, gfp_t gfp_mask,
struct page *page)
{
DECLARE_COMPLETION_ONSTACK(wait);
struct request_queue *q = bdev_get_queue(bdev);
unsigned int max_write_same_sectors;
struct bio_batch bb;
struct bio *bio;
int ret = 0;
if (!q)
return -ENXIO;
max_write_same_sectors = q->limits.max_write_same_sectors;
if (max_write_same_sectors == 0)
return -EOPNOTSUPP;
atomic_set(&bb.done, 1);
bb.error = 0;
bb.wait = &wait;
while (nr_sects) {
bio = bio_alloc(gfp_mask, 1);
if (!bio) {
ret = -ENOMEM;
break;
}
bio->bi_iter.bi_sector = sector;
bio->bi_end_io = bio_batch_end_io;
bio->bi_bdev = bdev;
bio->bi_private = &bb;
bio->bi_vcnt = 1;
bio->bi_io_vec->bv_page = page;
bio->bi_io_vec->bv_offset = 0;
bio->bi_io_vec->bv_len = bdev_logical_block_size(bdev);
if (nr_sects > max_write_same_sectors) {
bio->bi_iter.bi_size = max_write_same_sectors << 9;
nr_sects -= max_write_same_sectors;
sector += max_write_same_sectors;
} else {
bio->bi_iter.bi_size = nr_sects << 9;
nr_sects = 0;
}
atomic_inc(&bb.done);
submit_bio(REQ_WRITE | REQ_WRITE_SAME, bio);
}
/* Wait for bios in-flight */
if (!atomic_dec_and_test(&bb.done))
wait_for_completion_io(&wait);
if (bb.error)
return bb.error;
return ret;
}
EXPORT_SYMBOL(blkdev_issue_write_same);
/**
* 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)
*
* Description:
* Generate and issue number of bios with zerofiled pages.
*/
static int __blkdev_issue_zeroout(struct block_device *bdev, sector_t sector,
sector_t nr_sects, gfp_t gfp_mask)
{
int ret;
struct bio *bio;
struct bio_batch bb;
unsigned int sz;
DECLARE_COMPLETION_ONSTACK(wait);
atomic_set(&bb.done, 1);
bb.error = 0;
bb.wait = &wait;
ret = 0;
while (nr_sects != 0) {
bio = bio_alloc(gfp_mask,
min(nr_sects, (sector_t)BIO_MAX_PAGES));
if (!bio) {
ret = -ENOMEM;
break;
}
bio->bi_iter.bi_sector = sector;
bio->bi_bdev = bdev;
bio->bi_end_io = bio_batch_end_io;
bio->bi_private = &bb;
while (nr_sects != 0) {
sz = min((sector_t) PAGE_SIZE >> 9 , nr_sects);
ret = bio_add_page(bio, ZERO_PAGE(0), sz << 9, 0);
nr_sects -= ret >> 9;
sector += ret >> 9;
if (ret < (sz << 9))
break;
}
ret = 0;
atomic_inc(&bb.done);
submit_bio(WRITE, bio);
}
/* Wait for bios in-flight */
if (!atomic_dec_and_test(&bb.done))
wait_for_completion_io(&wait);
if (bb.error)
return bb.error;
return ret;
}
/**
* blkdev_issue_zeroout - zero-fill a block range
* @bdev: blockdev to write
* @sector: start sector
* @nr_sects: number of sectors to write
* @gfp_mask: memory allocation flags (for bio_alloc)
* @discard: whether to discard the block range
*
* Description:
* Zero-fill a block range. If the discard flag is set and the block
* device guarantees that subsequent READ operations to the block range
* in question will return zeroes, the blocks will be discarded. Should
* the discard request fail, if the discard flag is not set, or if
* discard_zeroes_data is not supported, this function will resort to
* zeroing the blocks manually, thus provisioning (allocating,
* anchoring) them. If the block device supports the WRITE SAME command
* blkdev_issue_zeroout() will use it to optimize the process of
* clearing the block range. Otherwise the zeroing will be performed
* using regular WRITE calls.
*/
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)
return 0;
if (bdev_write_same(bdev) &&
blkdev_issue_write_same(bdev, sector, nr_sects, gfp_mask,
ZERO_PAGE(0)) == 0)
return 0;
return __blkdev_issue_zeroout(bdev, sector, nr_sects, gfp_mask);
}
EXPORT_SYMBOL(blkdev_issue_zeroout);
