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 struct bio *next_bio(struct bio *bio, int rw, unsigned int nr_pages,
  13                 gfp_t gfp)
  14 {
  15         struct bio *new = bio_alloc(gfp, nr_pages);
  16
  17         if (bio) {
  18                 bio_chain(bio, new);
  19                 submit_bio(rw, bio);
  20         }
  21
  22         return new;
  23 }
  24
  25 int __blkdev_issue_discard(struct block_device *bdev, sector_t sector,
  26                 sector_t nr_sects, gfp_t gfp_mask, int type, struct bio **biop)
  27 {
  28         struct request_queue *q = bdev_get_queue(bdev);
  29         struct bio *bio = *biop;
  30         unsigned int granularity;
  31         int alignment;
  32
  33         if (!q)
  34                 return -ENXIO;
  35         if (!blk_queue_discard(q))
  36                 return -EOPNOTSUPP;
  37         if ((type & REQ_SECURE) && !blk_queue_secdiscard(q))
  38                 return -EOPNOTSUPP;
  39
  40         /* Zero-sector (unknown) and one-sector granularities are the same.  */
  41         granularity = max(q->limits.discard_granularity >> 9, 1U);
  42         alignment = (bdev_discard_alignment(bdev) >> 9) % granularity;
  43
  44         while (nr_sects) {
  45                 unsigned int req_sects;
  46                 sector_t end_sect, tmp;
  47
  48                 /* Make sure bi_size doesn't overflow */
  49                 req_sects = min_t(sector_t, nr_sects, UINT_MAX >> 9);
  50
  51                 /**
  52                  * If splitting a request, and the next starting sector would be
  53                  * misaligned, stop the discard at the previous aligned sector.
  54                  */
  55                 end_sect = sector + req_sects;
  56                 tmp = end_sect;
  57                 if (req_sects < nr_sects &&
  58                     sector_div(tmp, granularity) != alignment) {
  59                         end_sect = end_sect - alignment;
  60                         sector_div(end_sect, granularity);
  61                         end_sect = end_sect * granularity + alignment;
  62                         req_sects = end_sect - sector;
  63                 }
  64
  65                 bio = next_bio(bio, type, 1, gfp_mask);
  66                 bio->bi_iter.bi_sector = sector;
  67                 bio->bi_bdev = bdev;
  68
  69                 bio->bi_iter.bi_size = req_sects << 9;
  70                 nr_sects -= req_sects;
  71                 sector = end_sect;
  72
  73                 /*
  74                  * We can loop for a long time in here, if someone does
  75                  * full device discards (like mkfs). Be nice and allow
  76                  * us to schedule out to avoid softlocking if preempt
  77                  * is disabled.
  78                  */
  79                 cond_resched();
  80         }
  81
  82         *biop = bio;
  83         return 0;
  84 }
  85 EXPORT_SYMBOL(__blkdev_issue_discard);
  86
  87 /**
  88  * blkdev_issue_discard - queue a discard
  89  * @bdev:       blockdev to issue discard for
  90  * @sector:     start sector
  91  * @nr_sects:   number of sectors to discard
  92  * @gfp_mask:   memory allocation flags (for bio_alloc)
  93  * @flags:      BLKDEV_IFL_* flags to control behaviour
  94  *
  95  * Description:
  96  *    Issue a discard request for the sectors in question.
  97  */
  98 int blkdev_issue_discard(struct block_device *bdev, sector_t sector,
  99                 sector_t nr_sects, gfp_t gfp_mask, unsigned long flags)
 100 {
 101         int type = REQ_WRITE | REQ_DISCARD;
 102         struct bio *bio = NULL;
 103         struct blk_plug plug;
 104         int ret;
 105
 106         if (flags & BLKDEV_DISCARD_SECURE)
 107                 type |= REQ_SECURE;
 108
 109         blk_start_plug(&plug);
 110         ret = __blkdev_issue_discard(bdev, sector, nr_sects, gfp_mask, type,
 111                         &bio);
 112         if (!ret && bio) {
 113                 ret = submit_bio_wait(type, bio);
 114                 if (ret == -EOPNOTSUPP)
 115                         ret = 0;
 116         }
 117         blk_finish_plug(&plug);
 118
 119         return ret;
 120 }
 121 EXPORT_SYMBOL(blkdev_issue_discard);
 122
 123 /**
 124  * blkdev_issue_write_same - queue a write same operation
 125  * @bdev:       target blockdev
 126  * @sector:     start sector
 127  * @nr_sects:   number of sectors to write
 128  * @gfp_mask:   memory allocation flags (for bio_alloc)
 129  * @page:       page containing data to write
 130  *
 131  * Description:
 132  *    Issue a write same request for the sectors in question.
 133  */
 134 int blkdev_issue_write_same(struct block_device *bdev, sector_t sector,
 135                             sector_t nr_sects, gfp_t gfp_mask,
 136                             struct page *page)
 137 {
 138         struct request_queue *q = bdev_get_queue(bdev);
 139         unsigned int max_write_same_sectors;
 140         struct bio *bio = NULL;
 141         int ret = 0;
 142
 143         if (!q)
 144                 return -ENXIO;
 145
 146         /* Ensure that max_write_same_sectors doesn't overflow bi_size */
 147         max_write_same_sectors = UINT_MAX >> 9;
 148
 149         while (nr_sects) {
 150                 bio = next_bio(bio, REQ_WRITE | REQ_WRITE_SAME, 1, gfp_mask);
 151                 bio->bi_iter.bi_sector = sector;
 152                 bio->bi_bdev = bdev;
 153                 bio->bi_vcnt = 1;
 154                 bio->bi_io_vec->bv_page = page;
 155                 bio->bi_io_vec->bv_offset = 0;
 156                 bio->bi_io_vec->bv_len = bdev_logical_block_size(bdev);
 157
 158                 if (nr_sects > max_write_same_sectors) {
 159                         bio->bi_iter.bi_size = max_write_same_sectors << 9;
 160                         nr_sects -= max_write_same_sectors;
 161                         sector += max_write_same_sectors;
 162                 } else {
 163                         bio->bi_iter.bi_size = nr_sects << 9;
 164                         nr_sects = 0;
 165                 }
 166         }
 167
 168         if (bio)
 169                 ret = submit_bio_wait(REQ_WRITE | REQ_WRITE_SAME, bio);
 170         return ret != -EOPNOTSUPP ? ret : 0;
 171 }
 172 EXPORT_SYMBOL(blkdev_issue_write_same);
 173
 174 /**
 175  * blkdev_issue_zeroout - generate number of zero filed write bios
 176  * @bdev:       blockdev to issue
 177  * @sector:     start sector
 178  * @nr_sects:   number of sectors to write
 179  * @gfp_mask:   memory allocation flags (for bio_alloc)
 180  *
 181  * Description:
 182  *  Generate and issue number of bios with zerofiled pages.
 183  */
 184
 185 static int __blkdev_issue_zeroout(struct block_device *bdev, sector_t sector,
 186                                   sector_t nr_sects, gfp_t gfp_mask)
 187 {
 188         int ret;
 189         struct bio *bio = NULL;
 190         unsigned int sz;
 191
 192         while (nr_sects != 0) {
 193                 bio = next_bio(bio, WRITE,
 194                                 min(nr_sects, (sector_t)BIO_MAX_PAGES),
 195                                 gfp_mask);
 196                 bio->bi_iter.bi_sector = sector;
 197                 bio->bi_bdev   = bdev;
 198
 199                 while (nr_sects != 0) {
 200                         sz = min((sector_t) PAGE_SIZE >> 9 , nr_sects);
 201                         ret = bio_add_page(bio, ZERO_PAGE(0), sz << 9, 0);
 202                         nr_sects -= ret >> 9;
 203                         sector += ret >> 9;
 204                         if (ret < (sz << 9))
 205                                 break;
 206                 }
 207         }
 208
 209         if (bio)
 210                 return submit_bio_wait(WRITE, bio);
 211         return 0;
 212 }
 213
 214 /**
 215  * blkdev_issue_zeroout - zero-fill a block range
 216  * @bdev:       blockdev to write
 217  * @sector:     start sector
 218  * @nr_sects:   number of sectors to write
 219  * @gfp_mask:   memory allocation flags (for bio_alloc)
 220  * @discard:    whether to discard the block range
 221  *
 222  * Description:
 223  *  Zero-fill a block range.  If the discard flag is set and the block
 224  *  device guarantees that subsequent READ operations to the block range
 225  *  in question will return zeroes, the blocks will be discarded. Should
 226  *  the discard request fail, if the discard flag is not set, or if
 227  *  discard_zeroes_data is not supported, this function will resort to
 228  *  zeroing the blocks manually, thus provisioning (allocating,
 229  *  anchoring) them. If the block device supports the WRITE SAME command
 230  *  blkdev_issue_zeroout() will use it to optimize the process of
 231  *  clearing the block range. Otherwise the zeroing will be performed
 232  *  using regular WRITE calls.
 233  */
 234
 235 int blkdev_issue_zeroout(struct block_device *bdev, sector_t sector,
 236                          sector_t nr_sects, gfp_t gfp_mask, bool discard)
 237 {
 238         struct request_queue *q = bdev_get_queue(bdev);
 239
 240         if (discard && blk_queue_discard(q) && q->limits.discard_zeroes_data &&
 241             blkdev_issue_discard(bdev, sector, nr_sects, gfp_mask, 0) == 0)
 242                 return 0;
 243
 244         if (bdev_write_same(bdev) &&
 245             blkdev_issue_write_same(bdev, sector, nr_sects, gfp_mask,
 246                                     ZERO_PAGE(0)) == 0)
 247                 return 0;
 248
 249         return __blkdev_issue_zeroout(bdev, sector, nr_sects, gfp_mask);
 250 }
 251 EXPORT_SYMBOL(blkdev_issue_zeroout);