bbd848e0fa
Commit38f2525533("block: add __blkdev_issue_discard") incorrectly disallowed the early return of -EOPNOTSUPP if the device doesn't support discard (or secure discard). This early return of -EOPNOTSUPP has always been part of blkdev_issue_discard() interface so there isn't a good reason to break that behaviour -- especially when it can be easily reinstated. The nuance of allowing early return of -EOPNOTSUPP vs disallowing late return of -EOPNOTSUPP is: if the overall device never advertised support for discards and one is issued to the device it is beneficial to inform the caller that discards are not supported via -EOPNOTSUPP. But if a device advertises discard support it means that at least a subset of the device does have discard support -- but it could be that discards issued to some regions of a stacked device will not be supported. In that case the late return of -EOPNOTSUPP must be disallowed. Fixes:38f2525533("block: add __blkdev_issue_discard") Signed-off-by: Mike Snitzer <snitzer@redhat.com> Signed-off-by: Jens Axboe <axboe@fb.com>
252 lines
6.7 KiB
C
252 lines
6.7 KiB
C
/*
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* Functions related to generic helpers functions
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*/
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/bio.h>
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#include <linux/blkdev.h>
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#include <linux/scatterlist.h>
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#include "blk.h"
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static struct bio *next_bio(struct bio *bio, int rw, unsigned int nr_pages,
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gfp_t gfp)
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{
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struct bio *new = bio_alloc(gfp, nr_pages);
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if (bio) {
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bio_chain(bio, new);
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submit_bio(rw, bio);
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}
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return new;
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}
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int __blkdev_issue_discard(struct block_device *bdev, sector_t sector,
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sector_t nr_sects, gfp_t gfp_mask, int type, struct bio **biop)
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{
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struct request_queue *q = bdev_get_queue(bdev);
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struct bio *bio = *biop;
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unsigned int granularity;
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int alignment;
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if (!q)
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return -ENXIO;
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if (!blk_queue_discard(q))
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return -EOPNOTSUPP;
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if ((type & REQ_SECURE) && !blk_queue_secdiscard(q))
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return -EOPNOTSUPP;
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/* Zero-sector (unknown) and one-sector granularities are the same. */
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granularity = max(q->limits.discard_granularity >> 9, 1U);
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alignment = (bdev_discard_alignment(bdev) >> 9) % granularity;
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while (nr_sects) {
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unsigned int req_sects;
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sector_t end_sect, tmp;
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/* Make sure bi_size doesn't overflow */
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req_sects = min_t(sector_t, nr_sects, UINT_MAX >> 9);
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/**
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* If splitting a request, and the next starting sector would be
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* misaligned, stop the discard at the previous aligned sector.
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*/
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end_sect = sector + req_sects;
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tmp = end_sect;
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if (req_sects < nr_sects &&
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sector_div(tmp, granularity) != alignment) {
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end_sect = end_sect - alignment;
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sector_div(end_sect, granularity);
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end_sect = end_sect * granularity + alignment;
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req_sects = end_sect - sector;
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}
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bio = next_bio(bio, type, 1, gfp_mask);
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bio->bi_iter.bi_sector = sector;
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bio->bi_bdev = bdev;
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bio->bi_iter.bi_size = req_sects << 9;
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nr_sects -= req_sects;
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sector = end_sect;
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/*
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* We can loop for a long time in here, if someone does
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* full device discards (like mkfs). Be nice and allow
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* us to schedule out to avoid softlocking if preempt
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* is disabled.
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*/
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cond_resched();
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}
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*biop = bio;
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return 0;
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}
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EXPORT_SYMBOL(__blkdev_issue_discard);
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/**
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* blkdev_issue_discard - queue a discard
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* @bdev: blockdev to issue discard for
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* @sector: start sector
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* @nr_sects: number of sectors to discard
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* @gfp_mask: memory allocation flags (for bio_alloc)
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* @flags: BLKDEV_IFL_* flags to control behaviour
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*
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* Description:
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* Issue a discard request for the sectors in question.
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*/
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int blkdev_issue_discard(struct block_device *bdev, sector_t sector,
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sector_t nr_sects, gfp_t gfp_mask, unsigned long flags)
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{
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int type = REQ_WRITE | REQ_DISCARD;
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struct bio *bio = NULL;
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struct blk_plug plug;
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int ret;
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if (flags & BLKDEV_DISCARD_SECURE)
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type |= REQ_SECURE;
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blk_start_plug(&plug);
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ret = __blkdev_issue_discard(bdev, sector, nr_sects, gfp_mask, type,
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&bio);
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if (!ret && bio) {
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ret = submit_bio_wait(type, bio);
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if (ret == -EOPNOTSUPP)
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ret = 0;
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}
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blk_finish_plug(&plug);
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return ret;
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}
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EXPORT_SYMBOL(blkdev_issue_discard);
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/**
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* blkdev_issue_write_same - queue a write same operation
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* @bdev: target blockdev
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* @sector: start sector
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* @nr_sects: number of sectors to write
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* @gfp_mask: memory allocation flags (for bio_alloc)
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* @page: page containing data to write
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*
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* Description:
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* Issue a write same request for the sectors in question.
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*/
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int blkdev_issue_write_same(struct block_device *bdev, sector_t sector,
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sector_t nr_sects, gfp_t gfp_mask,
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struct page *page)
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{
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struct request_queue *q = bdev_get_queue(bdev);
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unsigned int max_write_same_sectors;
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struct bio *bio = NULL;
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int ret = 0;
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if (!q)
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return -ENXIO;
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/* Ensure that max_write_same_sectors doesn't overflow bi_size */
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max_write_same_sectors = UINT_MAX >> 9;
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while (nr_sects) {
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bio = next_bio(bio, REQ_WRITE | REQ_WRITE_SAME, 1, gfp_mask);
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bio->bi_iter.bi_sector = sector;
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bio->bi_bdev = bdev;
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bio->bi_vcnt = 1;
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bio->bi_io_vec->bv_page = page;
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bio->bi_io_vec->bv_offset = 0;
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bio->bi_io_vec->bv_len = bdev_logical_block_size(bdev);
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if (nr_sects > max_write_same_sectors) {
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bio->bi_iter.bi_size = max_write_same_sectors << 9;
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nr_sects -= max_write_same_sectors;
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sector += max_write_same_sectors;
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} else {
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bio->bi_iter.bi_size = nr_sects << 9;
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nr_sects = 0;
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}
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}
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if (bio)
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ret = submit_bio_wait(REQ_WRITE | REQ_WRITE_SAME, bio);
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return ret != -EOPNOTSUPP ? ret : 0;
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}
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EXPORT_SYMBOL(blkdev_issue_write_same);
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/**
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* blkdev_issue_zeroout - generate number of zero filed write bios
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* @bdev: blockdev to issue
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* @sector: start sector
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* @nr_sects: number of sectors to write
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* @gfp_mask: memory allocation flags (for bio_alloc)
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*
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* Description:
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* Generate and issue number of bios with zerofiled pages.
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*/
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static int __blkdev_issue_zeroout(struct block_device *bdev, sector_t sector,
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sector_t nr_sects, gfp_t gfp_mask)
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{
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int ret;
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struct bio *bio = NULL;
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unsigned int sz;
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while (nr_sects != 0) {
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bio = next_bio(bio, WRITE,
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min(nr_sects, (sector_t)BIO_MAX_PAGES),
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gfp_mask);
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bio->bi_iter.bi_sector = sector;
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bio->bi_bdev = bdev;
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while (nr_sects != 0) {
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sz = min((sector_t) PAGE_SIZE >> 9 , nr_sects);
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ret = bio_add_page(bio, ZERO_PAGE(0), sz << 9, 0);
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nr_sects -= ret >> 9;
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sector += ret >> 9;
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if (ret < (sz << 9))
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break;
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}
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}
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if (bio)
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return submit_bio_wait(WRITE, bio);
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return 0;
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}
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/**
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* blkdev_issue_zeroout - zero-fill a block range
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* @bdev: blockdev to write
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* @sector: start sector
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* @nr_sects: number of sectors to write
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* @gfp_mask: memory allocation flags (for bio_alloc)
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* @discard: whether to discard the block range
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*
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* Description:
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* Zero-fill a block range. If the discard flag is set and the block
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* device guarantees that subsequent READ operations to the block range
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* in question will return zeroes, the blocks will be discarded. Should
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* the discard request fail, if the discard flag is not set, or if
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* discard_zeroes_data is not supported, this function will resort to
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* zeroing the blocks manually, thus provisioning (allocating,
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* anchoring) them. If the block device supports the WRITE SAME command
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* blkdev_issue_zeroout() will use it to optimize the process of
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* clearing the block range. Otherwise the zeroing will be performed
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* using regular WRITE calls.
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*/
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int blkdev_issue_zeroout(struct block_device *bdev, sector_t sector,
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sector_t nr_sects, gfp_t gfp_mask, bool discard)
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{
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struct request_queue *q = bdev_get_queue(bdev);
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if (discard && blk_queue_discard(q) && q->limits.discard_zeroes_data &&
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blkdev_issue_discard(bdev, sector, nr_sects, gfp_mask, 0) == 0)
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return 0;
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if (bdev_write_same(bdev) &&
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blkdev_issue_write_same(bdev, sector, nr_sects, gfp_mask,
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ZERO_PAGE(0)) == 0)
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return 0;
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return __blkdev_issue_zeroout(bdev, sector, nr_sects, gfp_mask);
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}
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EXPORT_SYMBOL(blkdev_issue_zeroout);
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