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 = flags & BLKDEV_IFL_BARRIER ?
  43                 DISCARD_BARRIER : DISCARD_NOBARRIER;
  44         unsigned int max_discard_sectors;
  45         struct bio *bio;
  46         int ret = 0;
  47
  48         if (!q)
  49                 return -ENXIO;
  50
  51         if (!blk_queue_discard(q))
  52                 return -EOPNOTSUPP;
  53
  54         /*
  55          * Ensure that max_discard_sectors is of the proper
  56          * granularity
  57          */
  58         max_discard_sectors = min(q->limits.max_discard_sectors, UINT_MAX >> 9);
  59         if (q->limits.discard_granularity) {
  60                 unsigned int disc_sects = q->limits.discard_granularity >> 9;
  61
  62                 max_discard_sectors &= ~(disc_sects - 1);
  63         }
  64
  65         while (nr_sects && !ret) {
  66                 bio = bio_alloc(gfp_mask, 1);
  67                 if (!bio) {
  68                         ret = -ENOMEM;
  69                         break;
  70                 }
  71
  72                 bio->bi_sector = sector;
  73                 bio->bi_end_io = blkdev_discard_end_io;
  74                 bio->bi_bdev = bdev;
  75                 if (flags & BLKDEV_IFL_WAIT)
  76                         bio->bi_private = &wait;
  77
  78                 if (nr_sects > max_discard_sectors) {
  79                         bio->bi_size = max_discard_sectors << 9;
  80                         nr_sects -= max_discard_sectors;
  81                         sector += max_discard_sectors;
  82                 } else {
  83                         bio->bi_size = nr_sects << 9;
  84                         nr_sects = 0;
  85                 }
  86
  87                 bio_get(bio);
  88                 submit_bio(type, bio);
  89
  90                 if (flags & BLKDEV_IFL_WAIT)
  91                         wait_for_completion(&wait);
  92
  93                 if (bio_flagged(bio, BIO_EOPNOTSUPP))
  94                         ret = -EOPNOTSUPP;
  95                 else if (!bio_flagged(bio, BIO_UPTODATE))
  96                         ret = -EIO;
  97                 bio_put(bio);
  98         }
  99
 100         return ret;
 101 }
 102 EXPORT_SYMBOL(blkdev_issue_discard);
 103
 104 struct bio_batch
 105 {
 106         atomic_t                done;
 107         unsigned long           flags;
 108         struct completion       *wait;
 109         bio_end_io_t            *end_io;
 110 };
 111
 112 static void bio_batch_end_io(struct bio *bio, int err)
 113 {
 114         struct bio_batch *bb = bio->bi_private;
 115
 116         if (err) {
 117                 if (err == -EOPNOTSUPP)
 118                         set_bit(BIO_EOPNOTSUPP, &bb->flags);
 119                 else
 120                         clear_bit(BIO_UPTODATE, &bb->flags);
 121         }
 122         if (bb) {
 123                 if (bb->end_io)
 124                         bb->end_io(bio, err);
 125                 atomic_inc(&bb->done);
 126                 complete(bb->wait);
 127         }
 128         bio_put(bio);
 129 }
 130
 131 /**
 132  * blkdev_issue_zeroout generate number of zero filed write bios
 133  * @bdev:       blockdev to issue
 134  * @sector:     start sector
 135  * @nr_sects:   number of sectors to write
 136  * @gfp_mask:   memory allocation flags (for bio_alloc)
 137  * @flags:      BLKDEV_IFL_* flags to control behaviour
 138  *
 139  * Description:
 140  *  Generate and issue number of bios with zerofiled pages.
 141  *  Send barrier at the beginning and at the end if requested. This guarantie
 142  *  correct request ordering. Empty barrier allow us to avoid post queue flush.
 143  */
 144
 145 int blkdev_issue_zeroout(struct block_device *bdev, sector_t sector,
 146                         sector_t nr_sects, gfp_t gfp_mask, unsigned long flags)
 147 {
 148         int ret = 0;
 149         struct bio *bio;
 150         struct bio_batch bb;
 151         unsigned int sz, issued = 0;
 152         DECLARE_COMPLETION_ONSTACK(wait);
 153
 154         atomic_set(&bb.done, 0);
 155         bb.flags = 1 << BIO_UPTODATE;
 156         bb.wait = &wait;
 157         bb.end_io = NULL;
 158
 159         if (flags & BLKDEV_IFL_BARRIER) {
 160                 /* issue async barrier before the data */
 161                 ret = blkdev_issue_flush(bdev, gfp_mask, NULL, 0);
 162                 if (ret)
 163                         return ret;
 164         }
 165 submit:
 166         while (nr_sects != 0) {
 167                 bio = bio_alloc(gfp_mask,
 168                                 min(nr_sects, (sector_t)BIO_MAX_PAGES));
 169                 if (!bio)
 170                         break;
 171
 172                 bio->bi_sector = sector;
 173                 bio->bi_bdev   = bdev;
 174                 bio->bi_end_io = bio_batch_end_io;
 175                 if (flags & BLKDEV_IFL_WAIT)
 176                         bio->bi_private = &bb;
 177
 178                 while (nr_sects != 0) {
 179                         sz = min((sector_t) PAGE_SIZE >> 9 , nr_sects);
 180                         if (sz == 0)
 181                                 /* bio has maximum size possible */
 182                                 break;
 183                         ret = bio_add_page(bio, ZERO_PAGE(0), sz << 9, 0);
 184                         nr_sects -= ret >> 9;
 185                         sector += ret >> 9;
 186                         if (ret < (sz << 9))
 187                                 break;
 188                 }
 189                 issued++;
 190                 submit_bio(WRITE, bio);
 191         }
 192         /*
 193          * When all data bios are in flight. Send final barrier if requeted.
 194          */
 195         if (nr_sects == 0 && flags & BLKDEV_IFL_BARRIER)
 196                 ret = blkdev_issue_flush(bdev, gfp_mask, NULL,
 197                                         flags & BLKDEV_IFL_WAIT);
 198
 199
 200         if (flags & BLKDEV_IFL_WAIT)
 201                 /* Wait for bios in-flight */
 202                 while ( issued != atomic_read(&bb.done))
 203                         wait_for_completion(&wait);
 204
 205         if (!test_bit(BIO_UPTODATE, &bb.flags))
 206                 /* One of bios in the batch was completed with error.*/
 207                 ret = -EIO;
 208
 209         if (ret)
 210                 goto out;
 211
 212         if (test_bit(BIO_EOPNOTSUPP, &bb.flags)) {
 213                 ret = -EOPNOTSUPP;
 214                 goto out;
 215         }
 216         if (nr_sects != 0)
 217                 goto submit;
 218 out:
 219         return ret;
 220 }
 221 EXPORT_SYMBOL(blkdev_issue_zeroout);