block/blk-lib.c

   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
  12 struct bio_batch {
  13         atomic_t                done;
  14         unsigned long           flags;
  15         struct completion       *wait;
  16 };
  17
  18 static 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  */
  40 int 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         unsigned int granularity;
  48         struct bio_batch bb;
  49         struct bio *bio;
  50         int ret = 0;
  51
  52         if (!q)
  53                 return -ENXIO;
  54
  55         if (!blk_queue_discard(q))
  56                 return -EOPNOTSUPP;
  57
  58         /* Zero-sector (unknown) and one-sector granularities are the same.  */
  59         granularity = max(q->limits.discard_granularity >> 9, 1U);
  60
  61         /*
  62          * Ensure that max_discard_sectors is of the proper
  63          * granularity
  64          */
  65         max_discard_sectors = min(q->limits.max_discard_sectors, UINT_MAX >> 9);
  66         max_discard_sectors = round_down(max_discard_sectors, granularity);
  67         if (unlikely(!max_discard_sectors)) {
  68                 /* Avoid infinite loop below. Being cautious never hurts. */
  69                 return -EOPNOTSUPP;
  70         }
  71
  72         if (flags & BLKDEV_DISCARD_SECURE) {
  73                 if (!blk_queue_secdiscard(q))
  74                         return -EOPNOTSUPP;
  75                 type |= REQ_SECURE;
  76         }
  77
  78         atomic_set(&bb.done, 1);
  79         bb.flags = 1 << BIO_UPTODATE;
  80         bb.wait = &wait;
  81
  82         while (nr_sects) {
  83                 bio = bio_alloc(gfp_mask, 1);
  84                 if (!bio) {
  85                         ret = -ENOMEM;
  86                         break;
  87                 }
  88
  89                 bio->bi_sector = sector;
  90                 bio->bi_end_io = bio_batch_end_io;
  91                 bio->bi_bdev = bdev;
  92                 bio->bi_private = &bb;
  93
  94                 if (nr_sects > max_discard_sectors) {
  95                         bio->bi_size = max_discard_sectors << 9;
  96                         nr_sects -= max_discard_sectors;
  97                         sector += max_discard_sectors;
  98                 } else {
  99                         bio->bi_size = nr_sects << 9;
 100                         nr_sects = 0;
 101                 }
 102
 103                 atomic_inc(&bb.done);
 104                 submit_bio(type, bio);
 105         }
 106
 107         /* Wait for bios in-flight */
 108         if (!atomic_dec_and_test(&bb.done))
 109                 wait_for_completion(&wait);
 110
 111         if (!test_bit(BIO_UPTODATE, &bb.flags))
 112                 ret = -EIO;
 113
 114         return ret;
 115 }
 116 EXPORT_SYMBOL(blkdev_issue_discard);
 117
 118 /**
 119  * blkdev_issue_zeroout - generate number of zero filed write bios
 120  * @bdev:       blockdev to issue
 121  * @sector:     start sector
 122  * @nr_sects:   number of sectors to write
 123  * @gfp_mask:   memory allocation flags (for bio_alloc)
 124  *
 125  * Description:
 126  *  Generate and issue number of bios with zerofiled pages.
 127  */
 128
 129 int blkdev_issue_zeroout(struct block_device *bdev, sector_t sector,
 130                         sector_t nr_sects, gfp_t gfp_mask)
 131 {
 132         int ret;
 133         struct bio *bio;
 134         struct bio_batch bb;
 135         unsigned int sz;
 136         DECLARE_COMPLETION_ONSTACK(wait);
 137
 138         atomic_set(&bb.done, 1);
 139         bb.flags = 1 << BIO_UPTODATE;
 140         bb.wait = &wait;
 141
 142         ret = 0;
 143         while (nr_sects != 0) {
 144                 bio = bio_alloc(gfp_mask,
 145                                 min(nr_sects, (sector_t)BIO_MAX_PAGES));
 146                 if (!bio) {
 147                         ret = -ENOMEM;
 148                         break;
 149                 }
 150
 151                 bio->bi_sector = sector;
 152                 bio->bi_bdev   = bdev;
 153                 bio->bi_end_io = bio_batch_end_io;
 154                 bio->bi_private = &bb;
 155
 156                 while (nr_sects != 0) {
 157                         sz = min((sector_t) PAGE_SIZE >> 9 , nr_sects);
 158                         ret = bio_add_page(bio, ZERO_PAGE(0), sz << 9, 0);
 159                         nr_sects -= ret >> 9;
 160                         sector += ret >> 9;
 161                         if (ret < (sz << 9))
 162                                 break;
 163                 }
 164                 ret = 0;
 165                 atomic_inc(&bb.done);
 166                 submit_bio(WRITE, bio);
 167         }
 168
 169         /* Wait for bios in-flight */
 170         if (!atomic_dec_and_test(&bb.done))
 171                 wait_for_completion(&wait);
 172
 173         if (!test_bit(BIO_UPTODATE, &bb.flags))
 174                 /* One of bios in the batch was completed with error.*/
 175                 ret = -EIO;
 176
 177         return ret;
 178 }
 179 EXPORT_SYMBOL(blkdev_issue_zeroout);