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