linux/block/blk-lib.c
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   1/*
   2 * Functions related to generic helpers functions
   3 */
   4#include <linux/kernel.h>
   5#include <linux/module.h>
   6#include <linux/bio.h>
   7#include <linux/blkdev.h>
   8#include <linux/scatterlist.h>
   9
  10#include "blk.h"
  11
  12struct bio_batch {
  13        atomic_t                done;
  14        unsigned long           flags;
  15        struct completion       *wait;
  16};
  17
  18static void bio_batch_end_io(struct bio *bio, int err)
  19{
  20        struct bio_batch *bb = bio->bi_private;
  21
  22        if (err && (err != -EOPNOTSUPP))
  23                clear_bit(BIO_UPTODATE, &bb->flags);
  24        if (atomic_dec_and_test(&bb->done))
  25                complete(bb->wait);
  26        bio_put(bio);
  27}
  28
  29/**
  30 * blkdev_issue_discard - queue a discard
  31 * @bdev:       blockdev to issue discard for
  32 * @sector:     start sector
  33 * @nr_sects:   number of sectors to discard
  34 * @gfp_mask:   memory allocation flags (for bio_alloc)
  35 * @flags:      BLKDEV_IFL_* flags to control behaviour
  36 *
  37 * Description:
  38 *    Issue a discard request for the sectors in question.
  39 */
  40int blkdev_issue_discard(struct block_device *bdev, sector_t sector,
  41                sector_t nr_sects, gfp_t gfp_mask, unsigned long flags)
  42{
  43        DECLARE_COMPLETION_ONSTACK(wait);
  44        struct request_queue *q = bdev_get_queue(bdev);
  45        int type = REQ_WRITE | REQ_DISCARD;
  46        unsigned int max_discard_sectors;
  47        struct bio_batch bb;
  48        struct bio *bio;
  49        int ret = 0;
  50
  51        if (!q)
  52                return -ENXIO;
  53
  54        if (!blk_queue_discard(q))
  55                return -EOPNOTSUPP;
  56
  57        /*
  58         * Ensure that max_discard_sectors is of the proper
  59         * granularity
  60         */
  61        max_discard_sectors = min(q->limits.max_discard_sectors, UINT_MAX >> 9);
  62        if (unlikely(!max_discard_sectors)) {
  63                /* Avoid infinite loop below. Being cautious never hurts. */
  64                return -EOPNOTSUPP;
  65        } else if (q->limits.discard_granularity) {
  66                unsigned int disc_sects = q->limits.discard_granularity >> 9;
  67
  68                max_discard_sectors &= ~(disc_sects - 1);
  69        }
  70
  71        if (flags & BLKDEV_DISCARD_SECURE) {
  72                if (!blk_queue_secdiscard(q))
  73                        return -EOPNOTSUPP;
  74                type |= REQ_SECURE;
  75        }
  76
  77        atomic_set(&bb.done, 1);
  78        bb.flags = 1 << BIO_UPTODATE;
  79        bb.wait = &wait;
  80
  81        while (nr_sects) {
  82                bio = bio_alloc(gfp_mask, 1);
  83                if (!bio) {
  84                        ret = -ENOMEM;
  85                        break;
  86                }
  87
  88                bio->bi_sector = sector;
  89                bio->bi_end_io = bio_batch_end_io;
  90                bio->bi_bdev = bdev;
  91                bio->bi_private = &bb;
  92
  93                if (nr_sects > max_discard_sectors) {
  94                        bio->bi_size = max_discard_sectors << 9;
  95                        nr_sects -= max_discard_sectors;
  96                        sector += max_discard_sectors;
  97                } else {
  98                        bio->bi_size = nr_sects << 9;
  99                        nr_sects = 0;
 100                }
 101
 102                atomic_inc(&bb.done);
 103                submit_bio(type, bio);
 104        }
 105
 106        /* Wait for bios in-flight */
 107        if (!atomic_dec_and_test(&bb.done))
 108                wait_for_completion(&wait);
 109
 110        if (!test_bit(BIO_UPTODATE, &bb.flags))
 111                ret = -EIO;
 112
 113        return ret;
 114}
 115EXPORT_SYMBOL(blkdev_issue_discard);
 116
 117/**
 118 * blkdev_issue_zeroout - generate number of zero filed write bios
 119 * @bdev:       blockdev to issue
 120 * @sector:     start sector
 121 * @nr_sects:   number of sectors to write
 122 * @gfp_mask:   memory allocation flags (for bio_alloc)
 123 *
 124 * Description:
 125 *  Generate and issue number of bios with zerofiled pages.
 126 */
 127
 128int blkdev_issue_zeroout(struct block_device *bdev, sector_t sector,
 129                        sector_t nr_sects, gfp_t gfp_mask)
 130{
 131        int ret;
 132        struct bio *bio;
 133        struct bio_batch bb;
 134        unsigned int sz;
 135        DECLARE_COMPLETION_ONSTACK(wait);
 136
 137        atomic_set(&bb.done, 1);
 138        bb.flags = 1 << BIO_UPTODATE;
 139        bb.wait = &wait;
 140
 141        ret = 0;
 142        while (nr_sects != 0) {
 143                bio = bio_alloc(gfp_mask,
 144                                min(nr_sects, (sector_t)BIO_MAX_PAGES));
 145                if (!bio) {
 146                        ret = -ENOMEM;
 147                        break;
 148                }
 149
 150                bio->bi_sector = sector;
 151                bio->bi_bdev   = bdev;
 152                bio->bi_end_io = bio_batch_end_io;
 153                bio->bi_private = &bb;
 154
 155                while (nr_sects != 0) {
 156                        sz = min((sector_t) PAGE_SIZE >> 9 , nr_sects);
 157                        ret = bio_add_page(bio, ZERO_PAGE(0), sz << 9, 0);
 158                        nr_sects -= ret >> 9;
 159                        sector += ret >> 9;
 160                        if (ret < (sz << 9))
 161                                break;
 162                }
 163                ret = 0;
 164                atomic_inc(&bb.done);
 165                submit_bio(WRITE, bio);
 166        }
 167
 168        /* Wait for bios in-flight */
 169        if (!atomic_dec_and_test(&bb.done))
 170                wait_for_completion(&wait);
 171
 172        if (!test_bit(BIO_UPTODATE, &bb.flags))
 173                /* One of bios in the batch was completed with error.*/
 174                ret = -EIO;
 175
 176        return ret;
 177}
 178EXPORT_SYMBOL(blkdev_issue_zeroout);
 179
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