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 static void blkdev_discard_end_io(struct bio *bio, int err)
  13 {
  14         if (err) {
  15                 if (err == -EOPNOTSUPP)
  16                         set_bit(BIO_EOPNOTSUPP, &bio->bi_flags);
  17                 clear_bit(BIO_UPTODATE, &bio->bi_flags);
  18         }
  19
  20         if (bio->bi_private)
  21                 complete(bio->bi_private);
  22
  23         bio_put(bio);
  24 }
  25
  26 /**
  27  * blkdev_issue_discard - queue a discard
  28  * @bdev:       blockdev to issue discard for
  29  * @sector:     start sector
  30  * @nr_sects:   number of sectors to discard
  31  * @gfp_mask:   memory allocation flags (for bio_alloc)
  32  * @flags:      BLKDEV_IFL_* flags to control behaviour
  33  *
  34  * Description:
  35  *    Issue a discard request for the sectors in question.
  36  */
  37 int blkdev_issue_discard(struct block_device *bdev, sector_t sector,
  38                 sector_t nr_sects, gfp_t gfp_mask, unsigned long flags)
  39 {
  40         DECLARE_COMPLETION_ONSTACK(wait);
  41         struct request_queue *q = bdev_get_queue(bdev);
  42         int type = REQ_WRITE | REQ_DISCARD;
  43         unsigned int max_discard_sectors;
  44         struct bio *bio;
  45         int ret = 0;
  46
  47         if (!q)
  48                 return -ENXIO;
  49
  50         if (!blk_queue_discard(q))
  51                 return -EOPNOTSUPP;
  52
  53         /*
  54          * Ensure that max_discard_sectors is of the proper
  55          * granularity
  56          */
  57         max_discard_sectors = min(q->limits.max_discard_sectors, UINT_MAX >> 9);
  58         if (q->limits.discard_granularity) {
  59                 unsigned int disc_sects = q->limits.discard_granularity >> 9;
  60
  61                 max_discard_sectors &= ~(disc_sects - 1);
  62         }
  63
  64         if (flags & BLKDEV_DISCARD_SECURE) {
  65                 if (!blk_queue_secdiscard(q))
  66                         return -EOPNOTSUPP;
  67                 type |= REQ_SECURE;
  68         }
  69
  70         while (nr_sects && !ret) {
  71                 bio = bio_alloc(gfp_mask, 1);
  72                 if (!bio) {
  73                         ret = -ENOMEM;
  74                         break;
  75                 }
  76
  77                 bio->bi_sector = sector;
  78                 bio->bi_end_io = blkdev_discard_end_io;
  79                 bio->bi_bdev = bdev;
  80                 bio->bi_private = &wait;
  81
  82                 if (nr_sects > max_discard_sectors) {
  83                         bio->bi_size = max_discard_sectors << 9;
  84                         nr_sects -= max_discard_sectors;
  85                         sector += max_discard_sectors;
  86                 } else {
  87                         bio->bi_size = nr_sects << 9;
  88                         nr_sects = 0;
  89                 }
  90
  91                 bio_get(bio);
  92                 submit_bio(type, bio);
  93
  94                 wait_for_completion(&wait);
  95
  96                 if (bio_flagged(bio, BIO_EOPNOTSUPP))
  97                         ret = -EOPNOTSUPP;
  98                 else if (!bio_flagged(bio, BIO_UPTODATE))
  99                         ret = -EIO;
 100                 bio_put(bio);
 101         }
 102
 103         return ret;
 104 }
 105 EXPORT_SYMBOL(blkdev_issue_discard);
 106
 107 struct bio_batch
 108 {
 109         atomic_t                done;
 110         unsigned long           flags;
 111         struct completion       *wait;
 112 };
 113
 114 static void bio_batch_end_io(struct bio *bio, int err)
 115 {
 116         struct bio_batch *bb = bio->bi_private;
 117
 118         if (err) {
 119                 if (err == -EOPNOTSUPP)
 120                         set_bit(BIO_EOPNOTSUPP, &bb->flags);
 121                 else
 122                         clear_bit(BIO_UPTODATE, &bb->flags);
 123         }
 124         if (bb)
 125                 if (atomic_dec_and_test(&bb->done))
 126                         complete(bb->wait);
 127         bio_put(bio);
 128 }
 129
 130 /**
 131  * blkdev_issue_zeroout - generate number of zero filed write bios
 132  * @bdev:       blockdev to issue
 133  * @sector:     start sector
 134  * @nr_sects:   number of sectors to write
 135  * @gfp_mask:   memory allocation flags (for bio_alloc)
 136  *
 137  * Description:
 138  *  Generate and issue number of bios with zerofiled pages.
 139  *  Send barrier at the beginning and at the end if requested. This guarantie
 140  *  correct request ordering. Empty barrier allow us to avoid post queue flush.
 141  */
 142
 143 int blkdev_issue_zeroout(struct block_device *bdev, sector_t sector,
 144                         sector_t nr_sects, gfp_t gfp_mask)
 145 {
 146         int ret;
 147         struct bio *bio;
 148         struct bio_batch bb;
 149         unsigned int sz;
 150         DECLARE_COMPLETION_ONSTACK(wait);
 151
 152         atomic_set(&bb.done, 1);
 153         bb.flags = 1 << BIO_UPTODATE;
 154         bb.wait = &wait;
 155
 156 submit:
 157         ret = 0;
 158         while (nr_sects != 0) {
 159                 bio = bio_alloc(gfp_mask,
 160                                 min(nr_sects, (sector_t)BIO_MAX_PAGES));
 161                 if (!bio) {
 162                         ret = -ENOMEM;
 163                         break;
 164                 }
 165
 166                 bio->bi_sector = sector;
 167                 bio->bi_bdev   = bdev;
 168                 bio->bi_end_io = bio_batch_end_io;
 169                 bio->bi_private = &bb;
 170
 171                 while (nr_sects != 0) {
 172                         sz = min((sector_t) PAGE_SIZE >> 9 , nr_sects);
 173                         if (sz == 0)
 174                                 /* bio has maximum size possible */
 175                                 break;
 176                         ret = bio_add_page(bio, ZERO_PAGE(0), sz << 9, 0);
 177                         nr_sects -= ret >> 9;
 178                         sector += ret >> 9;
 179                         if (ret < (sz << 9))
 180                                 break;
 181                 }
 182                 ret = 0;
 183                 atomic_inc(&bb.done);
 184                 submit_bio(WRITE, bio);
 185         }
 186
 187         /* Wait for bios in-flight */
 188         if (!atomic_dec_and_test(&bb.done))
 189                 wait_for_completion(&wait);
 190
 191         if (!test_bit(BIO_UPTODATE, &bb.flags))
 192                 /* One of bios in the batch was completed with error.*/
 193                 ret = -EIO;
 194
 195         if (ret)
 196                 goto out;
 197
 198         if (test_bit(BIO_EOPNOTSUPP, &bb.flags)) {
 199                 ret = -EOPNOTSUPP;
 200                 goto out;
 201         }
 202         if (nr_sects != 0)
 203                 goto submit;
 204 out:
 205         return ret;
 206 }
 207 EXPORT_SYMBOL(blkdev_issue_zeroout);