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         blk_finish_plug(&plug);
 115
 116         return ret != -EOPNOTSUPP ? ret : 0;
 117 }
 118 EXPORT_SYMBOL(blkdev_issue_discard);
 119
 120 /**
 121  * blkdev_issue_write_same - queue a write same operation
 122  * @bdev:       target blockdev
 123  * @sector:     start sector
 124  * @nr_sects:   number of sectors to write
 125  * @gfp_mask:   memory allocation flags (for bio_alloc)
 126  * @page:       page containing data to write
 127  *
 128  * Description:
 129  *    Issue a write same request for the sectors in question.
 130  */
 131 int blkdev_issue_write_same(struct block_device *bdev, sector_t sector,
 132                             sector_t nr_sects, gfp_t gfp_mask,
 133                             struct page *page)
 134 {
 135         struct request_queue *q = bdev_get_queue(bdev);
 136         unsigned int max_write_same_sectors;
 137         struct bio *bio = NULL;
 138         int ret = 0;
 139
 140         if (!q)
 141                 return -ENXIO;
 142
 143         /* Ensure that max_write_same_sectors doesn't overflow bi_size */
 144         max_write_same_sectors = UINT_MAX >> 9;
 145
 146         while (nr_sects) {
 147                 bio = next_bio(bio, REQ_WRITE | REQ_WRITE_SAME, 1, gfp_mask);
 148                 bio->bi_iter.bi_sector = sector;
 149                 bio->bi_bdev = bdev;
 150                 bio->bi_vcnt = 1;
 151                 bio->bi_io_vec->bv_page = page;
 152                 bio->bi_io_vec->bv_offset = 0;
 153                 bio->bi_io_vec->bv_len = bdev_logical_block_size(bdev);
 154
 155                 if (nr_sects > max_write_same_sectors) {
 156                         bio->bi_iter.bi_size = max_write_same_sectors << 9;
 157                         nr_sects -= max_write_same_sectors;
 158                         sector += max_write_same_sectors;
 159                 } else {
 160                         bio->bi_iter.bi_size = nr_sects << 9;
 161                         nr_sects = 0;
 162                 }
 163         }
 164
 165         if (bio)
 166                 ret = submit_bio_wait(REQ_WRITE | REQ_WRITE_SAME, bio);
 167         return ret != -EOPNOTSUPP ? ret : 0;
 168 }
 169 EXPORT_SYMBOL(blkdev_issue_write_same);
 170
 171 /**
 172  * blkdev_issue_zeroout - generate number of zero filed write bios
 173  * @bdev:       blockdev to issue
 174  * @sector:     start sector
 175  * @nr_sects:   number of sectors to write
 176  * @gfp_mask:   memory allocation flags (for bio_alloc)
 177  *
 178  * Description:
 179  *  Generate and issue number of bios with zerofiled pages.
 180  */
 181
 182 static int __blkdev_issue_zeroout(struct block_device *bdev, sector_t sector,
 183                                   sector_t nr_sects, gfp_t gfp_mask)
 184 {
 185         int ret;
 186         struct bio *bio = NULL;
 187         unsigned int sz;
 188
 189         while (nr_sects != 0) {
 190                 bio = next_bio(bio, WRITE,
 191                                 min(nr_sects, (sector_t)BIO_MAX_PAGES),
 192                                 gfp_mask);
 193                 bio->bi_iter.bi_sector = sector;
 194                 bio->bi_bdev   = bdev;
 195
 196                 while (nr_sects != 0) {
 197                         sz = min((sector_t) PAGE_SIZE >> 9 , nr_sects);
 198                         ret = bio_add_page(bio, ZERO_PAGE(0), sz << 9, 0);
 199                         nr_sects -= ret >> 9;
 200                         sector += ret >> 9;
 201                         if (ret < (sz << 9))
 202                                 break;
 203                 }
 204         }
 205
 206         if (bio)
 207                 return submit_bio_wait(WRITE, bio);
 208         return 0;
 209 }
 210
 211 /**
 212  * blkdev_issue_zeroout - zero-fill a block range
 213  * @bdev:       blockdev to write
 214  * @sector:     start sector
 215  * @nr_sects:   number of sectors to write
 216  * @gfp_mask:   memory allocation flags (for bio_alloc)
 217  * @discard:    whether to discard the block range
 218  *
 219  * Description:
 220  *  Zero-fill a block range.  If the discard flag is set and the block
 221  *  device guarantees that subsequent READ operations to the block range
 222  *  in question will return zeroes, the blocks will be discarded. Should
 223  *  the discard request fail, if the discard flag is not set, or if
 224  *  discard_zeroes_data is not supported, this function will resort to
 225  *  zeroing the blocks manually, thus provisioning (allocating,
 226  *  anchoring) them. If the block device supports the WRITE SAME command
 227  *  blkdev_issue_zeroout() will use it to optimize the process of
 228  *  clearing the block range. Otherwise the zeroing will be performed
 229  *  using regular WRITE calls.
 230  */
 231
 232 int blkdev_issue_zeroout(struct block_device *bdev, sector_t sector,
 233                          sector_t nr_sects, gfp_t gfp_mask, bool discard)
 234 {
 235         struct request_queue *q = bdev_get_queue(bdev);
 236
 237         if (discard && blk_queue_discard(q) && q->limits.discard_zeroes_data &&
 238             blkdev_issue_discard(bdev, sector, nr_sects, gfp_mask, 0) == 0)
 239                 return 0;
 240
 241         if (bdev_write_same(bdev) &&
 242             blkdev_issue_write_same(bdev, sector, nr_sects, gfp_mask,
 243                                     ZERO_PAGE(0)) == 0)
 244                 return 0;
 245
 246         return __blkdev_issue_zeroout(bdev, sector, nr_sects, gfp_mask);
 247 }
 248 EXPORT_SYMBOL(blkdev_issue_zeroout);