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 struct bio_batch {
  13         atomic_t                done;
  14         unsigned long           flags;
  15         struct completion       *wait;
  16 };
  17
  18 static void bio_batch_end_io(struct bio *bio, int err)
  19 {
  20         struct bio_batch *bb = bio->bi_private;
  21
  22         if (err && (err != -EOPNOTSUPP))
  23                 clear_bit(BIO_UPTODATE, &bb->flags);
  24         if (atomic_dec_and_test(&bb->done))
  25                 complete(bb->wait);
  26         bio_put(bio);
  27 }
  28
  29 /**
  30  * blkdev_issue_discard - queue a discard
  31  * @bdev:       blockdev to issue discard for
  32  * @sector:     start sector
  33  * @nr_sects:   number of sectors to discard
  34  * @gfp_mask:   memory allocation flags (for bio_alloc)
  35  * @flags:      BLKDEV_IFL_* flags to control behaviour
  36  *
  37  * Description:
  38  *    Issue a discard request for the sectors in question.
  39  */
  40 int blkdev_issue_discard(struct block_device *bdev, sector_t sector,
  41                 sector_t nr_sects, gfp_t gfp_mask, unsigned long flags)
  42 {
  43         DECLARE_COMPLETION_ONSTACK(wait);
  44         struct request_queue *q = bdev_get_queue(bdev);
  45         int type = REQ_WRITE | REQ_DISCARD;
  46         unsigned int max_discard_sectors, granularity;
  47         int alignment;
  48         struct bio_batch bb;
  49         struct bio *bio;
  50         int ret = 0;
  51         struct blk_plug plug;
  52
  53         if (!q)
  54                 return -ENXIO;
  55
  56         if (!blk_queue_discard(q))
  57                 return -EOPNOTSUPP;
  58
  59         /* Zero-sector (unknown) and one-sector granularities are the same.  */
  60         granularity = max(q->limits.discard_granularity >> 9, 1U);
  61         alignment = (bdev_discard_alignment(bdev) >> 9) % granularity;
  62
  63         /*
  64          * Ensure that max_discard_sectors is of the proper
  65          * granularity, so that requests stay aligned after a split.
  66          */
  67         max_discard_sectors = min(q->limits.max_discard_sectors, UINT_MAX >> 9);
  68         max_discard_sectors -= max_discard_sectors % granularity;
  69         if (unlikely(!max_discard_sectors)) {
  70                 /* Avoid infinite loop below. Being cautious never hurts. */
  71                 return -EOPNOTSUPP;
  72         }
  73
  74         if (flags & BLKDEV_DISCARD_SECURE) {
  75                 if (!blk_queue_secdiscard(q))
  76                         return -EOPNOTSUPP;
  77                 type |= REQ_SECURE;
  78         }
  79
  80         atomic_set(&bb.done, 1);
  81         bb.flags = 1 << BIO_UPTODATE;
  82         bb.wait = &wait;
  83
  84         blk_start_plug(&plug);
  85         while (nr_sects) {
  86                 unsigned int req_sects;
  87                 sector_t end_sect, tmp;
  88
  89                 bio = bio_alloc(gfp_mask, 1);
  90                 if (!bio) {
  91                         ret = -ENOMEM;
  92                         break;
  93                 }
  94
  95                 req_sects = min_t(sector_t, nr_sects, max_discard_sectors);
  96
  97                 /*
  98                  * If splitting a request, and the next starting sector would be
  99                  * misaligned, stop the discard at the previous aligned sector.
 100                  */
 101                 end_sect = sector + req_sects;
 102                 tmp = end_sect;
 103                 if (req_sects < nr_sects &&
 104                     sector_div(tmp, granularity) != alignment) {
 105                         end_sect = end_sect - alignment;
 106                         sector_div(end_sect, granularity);
 107                         end_sect = end_sect * granularity + alignment;
 108                         req_sects = end_sect - sector;
 109                 }
 110
 111                 bio->bi_iter.bi_sector = sector;
 112                 bio->bi_end_io = bio_batch_end_io;
 113                 bio->bi_bdev = bdev;
 114                 bio->bi_private = &bb;
 115
 116                 bio->bi_iter.bi_size = req_sects << 9;
 117                 nr_sects -= req_sects;
 118                 sector = end_sect;
 119
 120                 atomic_inc(&bb.done);
 121                 submit_bio(type, bio);
 122
 123                 /*
 124                  * We can loop for a long time in here, if someone does
 125                  * full device discards (like mkfs). Be nice and allow
 126                  * us to schedule out to avoid softlocking if preempt
 127                  * is disabled.
 128                  */
 129                 cond_resched();
 130         }
 131         blk_finish_plug(&plug);
 132
 133         /* Wait for bios in-flight */
 134         if (!atomic_dec_and_test(&bb.done))
 135                 wait_for_completion_io(&wait);
 136
 137         if (!test_bit(BIO_UPTODATE, &bb.flags))
 138                 ret = -EIO;
 139
 140         return ret;
 141 }
 142 EXPORT_SYMBOL(blkdev_issue_discard);
 143
 144 /**
 145  * blkdev_issue_write_same - queue a write same operation
 146  * @bdev:       target blockdev
 147  * @sector:     start sector
 148  * @nr_sects:   number of sectors to write
 149  * @gfp_mask:   memory allocation flags (for bio_alloc)
 150  * @page:       page containing data to write
 151  *
 152  * Description:
 153  *    Issue a write same request for the sectors in question.
 154  */
 155 int blkdev_issue_write_same(struct block_device *bdev, sector_t sector,
 156                             sector_t nr_sects, gfp_t gfp_mask,
 157                             struct page *page)
 158 {
 159         DECLARE_COMPLETION_ONSTACK(wait);
 160         struct request_queue *q = bdev_get_queue(bdev);
 161         unsigned int max_write_same_sectors;
 162         struct bio_batch bb;
 163         struct bio *bio;
 164         int ret = 0;
 165
 166         if (!q)
 167                 return -ENXIO;
 168
 169         max_write_same_sectors = q->limits.max_write_same_sectors;
 170
 171         if (max_write_same_sectors == 0)
 172                 return -EOPNOTSUPP;
 173
 174         atomic_set(&bb.done, 1);
 175         bb.flags = 1 << BIO_UPTODATE;
 176         bb.wait = &wait;
 177
 178         while (nr_sects) {
 179                 bio = bio_alloc(gfp_mask, 1);
 180                 if (!bio) {
 181                         ret = -ENOMEM;
 182                         break;
 183                 }
 184
 185                 bio->bi_iter.bi_sector = sector;
 186                 bio->bi_end_io = bio_batch_end_io;
 187                 bio->bi_bdev = bdev;
 188                 bio->bi_private = &bb;
 189                 bio->bi_vcnt = 1;
 190                 bio->bi_io_vec->bv_page = page;
 191                 bio->bi_io_vec->bv_offset = 0;
 192                 bio->bi_io_vec->bv_len = bdev_logical_block_size(bdev);
 193
 194                 if (nr_sects > max_write_same_sectors) {
 195                         bio->bi_iter.bi_size = max_write_same_sectors << 9;
 196                         nr_sects -= max_write_same_sectors;
 197                         sector += max_write_same_sectors;
 198                 } else {
 199                         bio->bi_iter.bi_size = nr_sects << 9;
 200                         nr_sects = 0;
 201                 }
 202
 203                 atomic_inc(&bb.done);
 204                 submit_bio(REQ_WRITE | REQ_WRITE_SAME, bio);
 205         }
 206
 207         /* Wait for bios in-flight */
 208         if (!atomic_dec_and_test(&bb.done))
 209                 wait_for_completion_io(&wait);
 210
 211         if (!test_bit(BIO_UPTODATE, &bb.flags))
 212                 ret = -ENOTSUPP;
 213
 214         return ret;
 215 }
 216 EXPORT_SYMBOL(blkdev_issue_write_same);
 217
 218 /**
 219  * blkdev_issue_zeroout - generate number of zero filed write bios
 220  * @bdev:       blockdev to issue
 221  * @sector:     start sector
 222  * @nr_sects:   number of sectors to write
 223  * @gfp_mask:   memory allocation flags (for bio_alloc)
 224  *
 225  * Description:
 226  *  Generate and issue number of bios with zerofiled pages.
 227  */
 228
 229 static int __blkdev_issue_zeroout(struct block_device *bdev, sector_t sector,
 230                                   sector_t nr_sects, gfp_t gfp_mask)
 231 {
 232         int ret;
 233         struct bio *bio;
 234         struct bio_batch bb;
 235         unsigned int sz;
 236         DECLARE_COMPLETION_ONSTACK(wait);
 237
 238         atomic_set(&bb.done, 1);
 239         bb.flags = 1 << BIO_UPTODATE;
 240         bb.wait = &wait;
 241
 242         ret = 0;
 243         while (nr_sects != 0) {
 244                 bio = bio_alloc(gfp_mask,
 245                                 min(nr_sects, (sector_t)BIO_MAX_PAGES));
 246                 if (!bio) {
 247                         ret = -ENOMEM;
 248                         break;
 249                 }
 250
 251                 bio->bi_iter.bi_sector = sector;
 252                 bio->bi_bdev   = bdev;
 253                 bio->bi_end_io = bio_batch_end_io;
 254                 bio->bi_private = &bb;
 255
 256                 while (nr_sects != 0) {
 257                         sz = min((sector_t) PAGE_SIZE >> 9 , nr_sects);
 258                         ret = bio_add_page(bio, ZERO_PAGE(0), sz << 9, 0);
 259                         nr_sects -= ret >> 9;
 260                         sector += ret >> 9;
 261                         if (ret < (sz << 9))
 262                                 break;
 263                 }
 264                 ret = 0;
 265                 atomic_inc(&bb.done);
 266                 submit_bio(WRITE, bio);
 267         }
 268
 269         /* Wait for bios in-flight */
 270         if (!atomic_dec_and_test(&bb.done))
 271                 wait_for_completion_io(&wait);
 272
 273         if (!test_bit(BIO_UPTODATE, &bb.flags))
 274                 /* One of bios in the batch was completed with error.*/
 275                 ret = -EIO;
 276
 277         return ret;
 278 }
 279
 280 /**
 281  * blkdev_issue_zeroout - zero-fill a block range
 282  * @bdev:       blockdev to write
 283  * @sector:     start sector
 284  * @nr_sects:   number of sectors to write
 285  * @gfp_mask:   memory allocation flags (for bio_alloc)
 286  * @discard:    whether to discard the block range
 287  *
 288  * Description:
 289  *  Zero-fill a block range.  If the discard flag is set and the block
 290  *  device guarantees that subsequent READ operations to the block range
 291  *  in question will return zeroes, the blocks will be discarded. Should
 292  *  the discard request fail, if the discard flag is not set, or if
 293  *  discard_zeroes_data is not supported, this function will resort to
 294  *  zeroing the blocks manually, thus provisioning (allocating,
 295  *  anchoring) them. If the block device supports the WRITE SAME command
 296  *  blkdev_issue_zeroout() will use it to optimize the process of
 297  *  clearing the block range. Otherwise the zeroing will be performed
 298  *  using regular WRITE calls.
 299  */
 300
 301 int blkdev_issue_zeroout(struct block_device *bdev, sector_t sector,
 302                          sector_t nr_sects, gfp_t gfp_mask, bool discard)
 303 {
 304         struct request_queue *q = bdev_get_queue(bdev);
 305
 306         if (discard && blk_queue_discard(q) && q->limits.discard_zeroes_data &&
 307             blkdev_issue_discard(bdev, sector, nr_sects, gfp_mask, 0) == 0)
 308                 return 0;
 309
 310         if (bdev_write_same(bdev) &&
 311             blkdev_issue_write_same(bdev, sector, nr_sects, gfp_mask,
 312                                     ZERO_PAGE(0)) == 0)
 313                 return 0;
 314
 315         return __blkdev_issue_zeroout(bdev, sector, nr_sects, gfp_mask);
 316 }
 317 EXPORT_SYMBOL(blkdev_issue_zeroout);