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         __free_page(bio_page(bio));
  23
  24         bio_put(bio);
  25 }
  26
  27 /**
  28  * blkdev_issue_discard - queue a discard
  29  * @bdev:       blockdev to issue discard for
  30  * @sector:     start sector
  31  * @nr_sects:   number of sectors to discard
  32  * @gfp_mask:   memory allocation flags (for bio_alloc)
  33  * @flags:      BLKDEV_IFL_* flags to control behaviour
  34  *
  35  * Description:
  36  *    Issue a discard request for the sectors in question.
  37  */
  38 int blkdev_issue_discard(struct block_device *bdev, sector_t sector,
  39                 sector_t nr_sects, gfp_t gfp_mask, unsigned long flags)
  40 {
  41         DECLARE_COMPLETION_ONSTACK(wait);
  42         struct request_queue *q = bdev_get_queue(bdev);
  43         int type = flags & BLKDEV_IFL_BARRIER ?
  44                 DISCARD_BARRIER : DISCARD_NOBARRIER;
  45         struct bio *bio;
  46         struct page *page;
  47         int ret = 0;
  48
  49         if (!q)
  50                 return -ENXIO;
  51
  52         if (!blk_queue_discard(q))
  53                 return -EOPNOTSUPP;
  54
  55         while (nr_sects && !ret) {
  56                 unsigned int sector_size = q->limits.logical_block_size;
  57                 unsigned int max_discard_sectors =
  58                         min(q->limits.max_discard_sectors, UINT_MAX >> 9);
  59
  60                 bio = bio_alloc(gfp_mask, 1);
  61                 if (!bio)
  62                         goto out;
  63                 bio->bi_sector = sector;
  64                 bio->bi_end_io = blkdev_discard_end_io;
  65                 bio->bi_bdev = bdev;
  66                 if (flags & BLKDEV_IFL_WAIT)
  67                         bio->bi_private = &wait;
  68
  69                 /*
  70                  * Add a zeroed one-sector payload as that's what
  71                  * our current implementations need.  If we'll ever need
  72                  * more the interface will need revisiting.
  73                  */
  74                 page = alloc_page(gfp_mask | __GFP_ZERO);
  75                 if (!page)
  76                         goto out_free_bio;
  77                 if (bio_add_pc_page(q, bio, page, sector_size, 0) < sector_size)
  78                         goto out_free_page;
  79
  80                 /*
  81                  * And override the bio size - the way discard works we
  82                  * touch many more blocks on disk than the actual payload
  83                  * length.
  84                  */
  85                 if (nr_sects > max_discard_sectors) {
  86                         bio->bi_size = max_discard_sectors << 9;
  87                         nr_sects -= max_discard_sectors;
  88                         sector += max_discard_sectors;
  89                 } else {
  90                         bio->bi_size = nr_sects << 9;
  91                         nr_sects = 0;
  92                 }
  93
  94                 bio_get(bio);
  95                 submit_bio(type, bio);
  96
  97                 if (flags & BLKDEV_IFL_WAIT)
  98                         wait_for_completion(&wait);
  99
 100                 if (bio_flagged(bio, BIO_EOPNOTSUPP))
 101                         ret = -EOPNOTSUPP;
 102                 else if (!bio_flagged(bio, BIO_UPTODATE))
 103                         ret = -EIO;
 104                 bio_put(bio);
 105         }
 106         return ret;
 107 out_free_page:
 108         __free_page(page);
 109 out_free_bio:
 110         bio_put(bio);
 111 out:
 112         return -ENOMEM;
 113 }
 114 EXPORT_SYMBOL(blkdev_issue_discard);
 115
 116 struct bio_batch
 117 {
 118         atomic_t                done;
 119         unsigned long           flags;
 120         struct completion       *wait;
 121         bio_end_io_t            *end_io;
 122 };
 123
 124 static void bio_batch_end_io(struct bio *bio, int err)
 125 {
 126         struct bio_batch *bb = bio->bi_private;
 127
 128         if (err) {
 129                 if (err == -EOPNOTSUPP)
 130                         set_bit(BIO_EOPNOTSUPP, &bb->flags);
 131                 else
 132                         clear_bit(BIO_UPTODATE, &bb->flags);
 133         }
 134         if (bb) {
 135                 if (bb->end_io)
 136                         bb->end_io(bio, err);
 137                 atomic_inc(&bb->done);
 138                 complete(bb->wait);
 139         }
 140         bio_put(bio);
 141 }
 142
 143 /**
 144  * blkdev_issue_zeroout generate number of zero filed write bios
 145  * @bdev:       blockdev to issue
 146  * @sector:     start sector
 147  * @nr_sects:   number of sectors to write
 148  * @gfp_mask:   memory allocation flags (for bio_alloc)
 149  * @flags:      BLKDEV_IFL_* flags to control behaviour
 150  *
 151  * Description:
 152  *  Generate and issue number of bios with zerofiled pages.
 153  *  Send barrier at the beginning and at the end if requested. This guarantie
 154  *  correct request ordering. Empty barrier allow us to avoid post queue flush.
 155  */
 156
 157 int blkdev_issue_zeroout(struct block_device *bdev, sector_t sector,
 158                         sector_t nr_sects, gfp_t gfp_mask, unsigned long flags)
 159 {
 160         int ret = 0;
 161         struct bio *bio;
 162         struct bio_batch bb;
 163         unsigned int sz, issued = 0;
 164         DECLARE_COMPLETION_ONSTACK(wait);
 165
 166         atomic_set(&bb.done, 0);
 167         bb.flags = 1 << BIO_UPTODATE;
 168         bb.wait = &wait;
 169         bb.end_io = NULL;
 170
 171         if (flags & BLKDEV_IFL_BARRIER) {
 172                 /* issue async barrier before the data */
 173                 ret = blkdev_issue_flush(bdev, gfp_mask, NULL, 0);
 174                 if (ret)
 175                         return ret;
 176         }
 177 submit:
 178         while (nr_sects != 0) {
 179                 bio = bio_alloc(gfp_mask,
 180                                 min(nr_sects, (sector_t)BIO_MAX_PAGES));
 181                 if (!bio)
 182                         break;
 183
 184                 bio->bi_sector = sector;
 185                 bio->bi_bdev   = bdev;
 186                 bio->bi_end_io = bio_batch_end_io;
 187                 if (flags & BLKDEV_IFL_WAIT)
 188                         bio->bi_private = &bb;
 189
 190                 while (nr_sects != 0) {
 191                         sz = min((sector_t) PAGE_SIZE >> 9 , nr_sects);
 192                         if (sz == 0)
 193                                 /* bio has maximum size possible */
 194                                 break;
 195                         ret = bio_add_page(bio, ZERO_PAGE(0), sz << 9, 0);
 196                         nr_sects -= ret >> 9;
 197                         sector += ret >> 9;
 198                         if (ret < (sz << 9))
 199                                 break;
 200                 }
 201                 issued++;
 202                 submit_bio(WRITE, bio);
 203         }
 204         /*
 205          * When all data bios are in flight. Send final barrier if requeted.
 206          */
 207         if (nr_sects == 0 && flags & BLKDEV_IFL_BARRIER)
 208                 ret = blkdev_issue_flush(bdev, gfp_mask, NULL,
 209                                         flags & BLKDEV_IFL_WAIT);
 210
 211
 212         if (flags & BLKDEV_IFL_WAIT)
 213                 /* Wait for bios in-flight */
 214                 while ( issued != atomic_read(&bb.done))
 215                         wait_for_completion(&wait);
 216
 217         if (!test_bit(BIO_UPTODATE, &bb.flags))
 218                 /* One of bios in the batch was completed with error.*/
 219                 ret = -EIO;
 220
 221         if (ret)
 222                 goto out;
 223
 224         if (test_bit(BIO_EOPNOTSUPP, &bb.flags)) {
 225                 ret = -EOPNOTSUPP;
 226                 goto out;
 227         }
 228         if (nr_sects != 0)
 229                 goto submit;
 230 out:
 231         return ret;
 232 }
 233 EXPORT_SYMBOL(blkdev_issue_zeroout);