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         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                  * We can loop for a long time in here, if someone does
 107                  * full device discards (like mkfs). Be nice and allow
 108                  * us to schedule out to avoid softlocking if preempt
 109                  * is disabled.
 110                  */
 111                 cond_resched();
 112         }
 113
 114         /* Wait for bios in-flight */
 115         if (!atomic_dec_and_test(&bb.done))
 116                 wait_for_completion(&wait);
 117
 118         if (!test_bit(BIO_UPTODATE, &bb.flags))
 119                 ret = -EIO;
 120
 121         return ret;
 122 }
 123 EXPORT_SYMBOL(blkdev_issue_discard);
 124
 125 /**
 126  * blkdev_issue_zeroout - generate number of zero filed write bios
 127  * @bdev:       blockdev to issue
 128  * @sector:     start sector
 129  * @nr_sects:   number of sectors to write
 130  * @gfp_mask:   memory allocation flags (for bio_alloc)
 131  *
 132  * Description:
 133  *  Generate and issue number of bios with zerofiled pages.
 134  */
 135
 136 int blkdev_issue_zeroout(struct block_device *bdev, sector_t sector,
 137                         sector_t nr_sects, gfp_t gfp_mask)
 138 {
 139         int ret;
 140         struct bio *bio;
 141         struct bio_batch bb;
 142         unsigned int sz;
 143         DECLARE_COMPLETION_ONSTACK(wait);
 144
 145         atomic_set(&bb.done, 1);
 146         bb.flags = 1 << BIO_UPTODATE;
 147         bb.wait = &wait;
 148
 149         ret = 0;
 150         while (nr_sects != 0) {
 151                 bio = bio_alloc(gfp_mask,
 152                                 min(nr_sects, (sector_t)BIO_MAX_PAGES));
 153                 if (!bio) {
 154                         ret = -ENOMEM;
 155                         break;
 156                 }
 157
 158                 bio->bi_sector = sector;
 159                 bio->bi_bdev   = bdev;
 160                 bio->bi_end_io = bio_batch_end_io;
 161                 bio->bi_private = &bb;
 162
 163                 while (nr_sects != 0) {
 164                         sz = min((sector_t) PAGE_SIZE >> 9 , nr_sects);
 165                         ret = bio_add_page(bio, ZERO_PAGE(0), sz << 9, 0);
 166                         nr_sects -= ret >> 9;
 167                         sector += ret >> 9;
 168                         if (ret < (sz << 9))
 169                                 break;
 170                 }
 171                 ret = 0;
 172                 atomic_inc(&bb.done);
 173                 submit_bio(WRITE, bio);
 174         }
 175
 176         /* Wait for bios in-flight */
 177         if (!atomic_dec_and_test(&bb.done))
 178                 wait_for_completion(&wait);
 179
 180         if (!test_bit(BIO_UPTODATE, &bb.flags))
 181                 /* One of bios in the batch was completed with error.*/
 182                 ret = -EIO;
 183
 184         return ret;
 185 }
 186 EXPORT_SYMBOL(blkdev_issue_zeroout);