root/block/blk-lib.c

DEFINITIONS

1. blk_next_bio
2. __blkdev_issue_discard
3. blkdev_issue_discard
4. __blkdev_issue_write_same
5. blkdev_issue_write_same
6. __blkdev_issue_write_zeroes
7. __blkdev_sectors_to_bio_pages
8. __blkdev_issue_zero_pages
9. __blkdev_issue_zeroout
10. blkdev_issue_zeroout

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Functions related to generic helpers functions
   4  */
   5 #include <linux/kernel.h>
   6 #include <linux/module.h>
   7 #include <linux/bio.h>
   8 #include <linux/blkdev.h>
   9 #include <linux/scatterlist.h>
  10 
  11 #include "blk.h"
  12 
  13 struct bio *blk_next_bio(struct bio *bio, unsigned int nr_pages, 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(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 flags,
  27                 struct bio **biop)
  28 {
  29         struct request_queue *q = bdev_get_queue(bdev);
  30         struct bio *bio = *biop;
  31         unsigned int op;
  32         sector_t bs_mask;
  33 
  34         if (!q)
  35                 return -ENXIO;
  36 
  37         if (bdev_read_only(bdev))
  38                 return -EPERM;
  39 
  40         if (flags & BLKDEV_DISCARD_SECURE) {
  41                 if (!blk_queue_secure_erase(q))
  42                         return -EOPNOTSUPP;
  43                 op = REQ_OP_SECURE_ERASE;
  44         } else {
  45                 if (!blk_queue_discard(q))
  46                         return -EOPNOTSUPP;
  47                 op = REQ_OP_DISCARD;
  48         }
  49 
  50         bs_mask = (bdev_logical_block_size(bdev) >> 9) - 1;
  51         if ((sector | nr_sects) & bs_mask)
  52                 return -EINVAL;
  53 
  54         if (!nr_sects)
  55                 return -EINVAL;
  56 
  57         while (nr_sects) {
  58                 sector_t req_sects = min_t(sector_t, nr_sects,
  59                                 bio_allowed_max_sectors(q));
  60 
  61                 WARN_ON_ONCE((req_sects << 9) > UINT_MAX);
  62 
  63                 bio = blk_next_bio(bio, 0, gfp_mask);
  64                 bio->bi_iter.bi_sector = sector;
  65                 bio_set_dev(bio, bdev);
  66                 bio_set_op_attrs(bio, op, 0);
  67 
  68                 bio->bi_iter.bi_size = req_sects << 9;
  69                 sector += req_sects;
  70                 nr_sects -= req_sects;
  71 
  72                 /*
  73                  * We can loop for a long time in here, if someone does
  74                  * full device discards (like mkfs). Be nice and allow
  75                  * us to schedule out to avoid softlocking if preempt
  76                  * is disabled.
  77                  */
  78                 cond_resched();
  79         }
  80 
  81         *biop = bio;
  82         return 0;
  83 }
  84 EXPORT_SYMBOL(__blkdev_issue_discard);
  85 
  86 /**
  87  * blkdev_issue_discard - queue a discard
  88  * @bdev:       blockdev to issue discard for
  89  * @sector:     start sector
  90  * @nr_sects:   number of sectors to discard
  91  * @gfp_mask:   memory allocation flags (for bio_alloc)
  92  * @flags:      BLKDEV_DISCARD_* flags to control behaviour
  93  *
  94  * Description:
  95  *    Issue a discard request for the sectors in question.
  96  */
  97 int blkdev_issue_discard(struct block_device *bdev, sector_t sector,
  98                 sector_t nr_sects, gfp_t gfp_mask, unsigned long flags)
  99 {
 100         struct bio *bio = NULL;
 101         struct blk_plug plug;
 102         int ret;
 103 
 104         blk_start_plug(&plug);
 105         ret = __blkdev_issue_discard(bdev, sector, nr_sects, gfp_mask, flags,
 106                         &bio);
 107         if (!ret && bio) {
 108                 ret = submit_bio_wait(bio);
 109                 if (ret == -EOPNOTSUPP)
 110                         ret = 0;
 111                 bio_put(bio);
 112         }
 113         blk_finish_plug(&plug);
 114 
 115         return ret;
 116 }
 117 EXPORT_SYMBOL(blkdev_issue_discard);
 118 
 119 /**
 120  * __blkdev_issue_write_same - generate number of bios with same page
 121  * @bdev:       target blockdev
 122  * @sector:     start sector
 123  * @nr_sects:   number of sectors to write
 124  * @gfp_mask:   memory allocation flags (for bio_alloc)
 125  * @page:       page containing data to write
 126  * @biop:       pointer to anchor bio
 127  *
 128  * Description:
 129  *  Generate and issue number of bios(REQ_OP_WRITE_SAME) with same page.
 130  */
 131 static int __blkdev_issue_write_same(struct block_device *bdev, sector_t sector,
 132                 sector_t nr_sects, gfp_t gfp_mask, struct page *page,
 133                 struct bio **biop)
 134 {
 135         struct request_queue *q = bdev_get_queue(bdev);
 136         unsigned int max_write_same_sectors;
 137         struct bio *bio = *biop;
 138         sector_t bs_mask;
 139 
 140         if (!q)
 141                 return -ENXIO;
 142 
 143         if (bdev_read_only(bdev))
 144                 return -EPERM;
 145 
 146         bs_mask = (bdev_logical_block_size(bdev) >> 9) - 1;
 147         if ((sector | nr_sects) & bs_mask)
 148                 return -EINVAL;
 149 
 150         if (!bdev_write_same(bdev))
 151                 return -EOPNOTSUPP;
 152 
 153         /* Ensure that max_write_same_sectors doesn't overflow bi_size */
 154         max_write_same_sectors = bio_allowed_max_sectors(q);
 155 
 156         while (nr_sects) {
 157                 bio = blk_next_bio(bio, 1, gfp_mask);
 158                 bio->bi_iter.bi_sector = sector;
 159                 bio_set_dev(bio, bdev);
 160                 bio->bi_vcnt = 1;
 161                 bio->bi_io_vec->bv_page = page;
 162                 bio->bi_io_vec->bv_offset = 0;
 163                 bio->bi_io_vec->bv_len = bdev_logical_block_size(bdev);
 164                 bio_set_op_attrs(bio, REQ_OP_WRITE_SAME, 0);
 165 
 166                 if (nr_sects > max_write_same_sectors) {
 167                         bio->bi_iter.bi_size = max_write_same_sectors << 9;
 168                         nr_sects -= max_write_same_sectors;
 169                         sector += max_write_same_sectors;
 170                 } else {
 171                         bio->bi_iter.bi_size = nr_sects << 9;
 172                         nr_sects = 0;
 173                 }
 174                 cond_resched();
 175         }
 176 
 177         *biop = bio;
 178         return 0;
 179 }
 180 
 181 /**
 182  * blkdev_issue_write_same - queue a write same operation
 183  * @bdev:       target blockdev
 184  * @sector:     start sector
 185  * @nr_sects:   number of sectors to write
 186  * @gfp_mask:   memory allocation flags (for bio_alloc)
 187  * @page:       page containing data
 188  *
 189  * Description:
 190  *    Issue a write same request for the sectors in question.
 191  */
 192 int blkdev_issue_write_same(struct block_device *bdev, sector_t sector,
 193                                 sector_t nr_sects, gfp_t gfp_mask,
 194                                 struct page *page)
 195 {
 196         struct bio *bio = NULL;
 197         struct blk_plug plug;
 198         int ret;
 199 
 200         blk_start_plug(&plug);
 201         ret = __blkdev_issue_write_same(bdev, sector, nr_sects, gfp_mask, page,
 202                         &bio);
 203         if (ret == 0 && bio) {
 204                 ret = submit_bio_wait(bio);
 205                 bio_put(bio);
 206         }
 207         blk_finish_plug(&plug);
 208         return ret;
 209 }
 210 EXPORT_SYMBOL(blkdev_issue_write_same);
 211 
 212 static int __blkdev_issue_write_zeroes(struct block_device *bdev,
 213                 sector_t sector, sector_t nr_sects, gfp_t gfp_mask,
 214                 struct bio **biop, unsigned flags)
 215 {
 216         struct bio *bio = *biop;
 217         unsigned int max_write_zeroes_sectors;
 218         struct request_queue *q = bdev_get_queue(bdev);
 219 
 220         if (!q)
 221                 return -ENXIO;
 222 
 223         if (bdev_read_only(bdev))
 224                 return -EPERM;
 225 
 226         /* Ensure that max_write_zeroes_sectors doesn't overflow bi_size */
 227         max_write_zeroes_sectors = bdev_write_zeroes_sectors(bdev);
 228 
 229         if (max_write_zeroes_sectors == 0)
 230                 return -EOPNOTSUPP;
 231 
 232         while (nr_sects) {
 233                 bio = blk_next_bio(bio, 0, gfp_mask);
 234                 bio->bi_iter.bi_sector = sector;
 235                 bio_set_dev(bio, bdev);
 236                 bio->bi_opf = REQ_OP_WRITE_ZEROES;
 237                 if (flags & BLKDEV_ZERO_NOUNMAP)
 238                         bio->bi_opf |= REQ_NOUNMAP;
 239 
 240                 if (nr_sects > max_write_zeroes_sectors) {
 241                         bio->bi_iter.bi_size = max_write_zeroes_sectors << 9;
 242                         nr_sects -= max_write_zeroes_sectors;
 243                         sector += max_write_zeroes_sectors;
 244                 } else {
 245                         bio->bi_iter.bi_size = nr_sects << 9;
 246                         nr_sects = 0;
 247                 }
 248                 cond_resched();
 249         }
 250 
 251         *biop = bio;
 252         return 0;
 253 }
 254 
 255 /*
 256  * Convert a number of 512B sectors to a number of pages.
 257  * The result is limited to a number of pages that can fit into a BIO.
 258  * Also make sure that the result is always at least 1 (page) for the cases
 259  * where nr_sects is lower than the number of sectors in a page.
 260  */
 261 static unsigned int __blkdev_sectors_to_bio_pages(sector_t nr_sects)
 262 {
 263         sector_t pages = DIV_ROUND_UP_SECTOR_T(nr_sects, PAGE_SIZE / 512);
 264 
 265         return min(pages, (sector_t)BIO_MAX_PAGES);
 266 }
 267 
 268 static int __blkdev_issue_zero_pages(struct block_device *bdev,
 269                 sector_t sector, sector_t nr_sects, gfp_t gfp_mask,
 270                 struct bio **biop)
 271 {
 272         struct request_queue *q = bdev_get_queue(bdev);
 273         struct bio *bio = *biop;
 274         int bi_size = 0;
 275         unsigned int sz;
 276 
 277         if (!q)
 278                 return -ENXIO;
 279 
 280         if (bdev_read_only(bdev))
 281                 return -EPERM;
 282 
 283         while (nr_sects != 0) {
 284                 bio = blk_next_bio(bio, __blkdev_sectors_to_bio_pages(nr_sects),
 285                                    gfp_mask);
 286                 bio->bi_iter.bi_sector = sector;
 287                 bio_set_dev(bio, bdev);
 288                 bio_set_op_attrs(bio, REQ_OP_WRITE, 0);
 289 
 290                 while (nr_sects != 0) {
 291                         sz = min((sector_t) PAGE_SIZE, nr_sects << 9);
 292                         bi_size = bio_add_page(bio, ZERO_PAGE(0), sz, 0);
 293                         nr_sects -= bi_size >> 9;
 294                         sector += bi_size >> 9;
 295                         if (bi_size < sz)
 296                                 break;
 297                 }
 298                 cond_resched();
 299         }
 300 
 301         *biop = bio;
 302         return 0;
 303 }
 304 
 305 /**
 306  * __blkdev_issue_zeroout - generate number of zero filed write bios
 307  * @bdev:       blockdev to issue
 308  * @sector:     start sector
 309  * @nr_sects:   number of sectors to write
 310  * @gfp_mask:   memory allocation flags (for bio_alloc)
 311  * @biop:       pointer to anchor bio
 312  * @flags:      controls detailed behavior
 313  *
 314  * Description:
 315  *  Zero-fill a block range, either using hardware offload or by explicitly
 316  *  writing zeroes to the device.
 317  *
 318  *  If a device is using logical block provisioning, the underlying space will
 319  *  not be released if %flags contains BLKDEV_ZERO_NOUNMAP.
 320  *
 321  *  If %flags contains BLKDEV_ZERO_NOFALLBACK, the function will return
 322  *  -EOPNOTSUPP if no explicit hardware offload for zeroing is provided.
 323  */
 324 int __blkdev_issue_zeroout(struct block_device *bdev, sector_t sector,
 325                 sector_t nr_sects, gfp_t gfp_mask, struct bio **biop,
 326                 unsigned flags)
 327 {
 328         int ret;
 329         sector_t bs_mask;
 330 
 331         bs_mask = (bdev_logical_block_size(bdev) >> 9) - 1;
 332         if ((sector | nr_sects) & bs_mask)
 333                 return -EINVAL;
 334 
 335         ret = __blkdev_issue_write_zeroes(bdev, sector, nr_sects, gfp_mask,
 336                         biop, flags);
 337         if (ret != -EOPNOTSUPP || (flags & BLKDEV_ZERO_NOFALLBACK))
 338                 return ret;
 339 
 340         return __blkdev_issue_zero_pages(bdev, sector, nr_sects, gfp_mask,
 341                                          biop);
 342 }
 343 EXPORT_SYMBOL(__blkdev_issue_zeroout);
 344 
 345 /**
 346  * blkdev_issue_zeroout - zero-fill a block range
 347  * @bdev:       blockdev to write
 348  * @sector:     start sector
 349  * @nr_sects:   number of sectors to write
 350  * @gfp_mask:   memory allocation flags (for bio_alloc)
 351  * @flags:      controls detailed behavior
 352  *
 353  * Description:
 354  *  Zero-fill a block range, either using hardware offload or by explicitly
 355  *  writing zeroes to the device.  See __blkdev_issue_zeroout() for the
 356  *  valid values for %flags.
 357  */
 358 int blkdev_issue_zeroout(struct block_device *bdev, sector_t sector,
 359                 sector_t nr_sects, gfp_t gfp_mask, unsigned flags)
 360 {
 361         int ret = 0;
 362         sector_t bs_mask;
 363         struct bio *bio;
 364         struct blk_plug plug;
 365         bool try_write_zeroes = !!bdev_write_zeroes_sectors(bdev);
 366 
 367         bs_mask = (bdev_logical_block_size(bdev) >> 9) - 1;
 368         if ((sector | nr_sects) & bs_mask)
 369                 return -EINVAL;
 370 
 371 retry:
 372         bio = NULL;
 373         blk_start_plug(&plug);
 374         if (try_write_zeroes) {
 375                 ret = __blkdev_issue_write_zeroes(bdev, sector, nr_sects,
 376                                                   gfp_mask, &bio, flags);
 377         } else if (!(flags & BLKDEV_ZERO_NOFALLBACK)) {
 378                 ret = __blkdev_issue_zero_pages(bdev, sector, nr_sects,
 379                                                 gfp_mask, &bio);
 380         } else {
 381                 /* No zeroing offload support */
 382                 ret = -EOPNOTSUPP;
 383         }
 384         if (ret == 0 && bio) {
 385                 ret = submit_bio_wait(bio);
 386                 bio_put(bio);
 387         }
 388         blk_finish_plug(&plug);
 389         if (ret && try_write_zeroes) {
 390                 if (!(flags & BLKDEV_ZERO_NOFALLBACK)) {
 391                         try_write_zeroes = false;
 392                         goto retry;
 393                 }
 394                 if (!bdev_write_zeroes_sectors(bdev)) {
 395                         /*
 396                          * Zeroing offload support was indicated, but the
 397                          * device reported ILLEGAL REQUEST (for some devices
 398                          * there is no non-destructive way to verify whether
 399                          * WRITE ZEROES is actually supported).
 400                          */
 401                         ret = -EOPNOTSUPP;
 402                 }
 403         }
 404 
 405         return ret;
 406 }
 407 EXPORT_SYMBOL(blkdev_issue_zeroout);