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, 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(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 granularity; 32 enum req_op op; 33 int alignment; 34 35 if (!q) 36 return -ENXIO; 37 38 if (flags & BLKDEV_DISCARD_SECURE) { 39 if (flags & BLKDEV_DISCARD_ZERO) 40 return -EOPNOTSUPP; 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 if ((flags & BLKDEV_DISCARD_ZERO) && 48 !q->limits.discard_zeroes_data) 49 return -EOPNOTSUPP; 50 op = REQ_OP_DISCARD; 51 } 52 53 /* Zero-sector (unknown) and one-sector granularities are the same. */ 54 granularity = max(q->limits.discard_granularity >> 9, 1U); 55 alignment = (bdev_discard_alignment(bdev) >> 9) % granularity; 56 57 while (nr_sects) { 58 unsigned int req_sects; 59 sector_t end_sect, tmp; 60 61 /* Make sure bi_size doesn't overflow */ 62 req_sects = min_t(sector_t, nr_sects, UINT_MAX >> 9); 63 64 /** 65 * If splitting a request, and the next starting sector would be 66 * misaligned, stop the discard at the previous aligned sector. 67 */ 68 end_sect = sector + req_sects; 69 tmp = end_sect; 70 if (req_sects < nr_sects && 71 sector_div(tmp, granularity) != alignment) { 72 end_sect = end_sect - alignment; 73 sector_div(end_sect, granularity); 74 end_sect = end_sect * granularity + alignment; 75 req_sects = end_sect - sector; 76 } 77 78 bio = next_bio(bio, 1, gfp_mask); 79 bio->bi_iter.bi_sector = sector; 80 bio->bi_bdev = bdev; 81 bio_set_op_attrs(bio, op, 0); 82 83 bio->bi_iter.bi_size = req_sects << 9; 84 nr_sects -= req_sects; 85 sector = end_sect; 86 87 /* 88 * We can loop for a long time in here, if someone does 89 * full device discards (like mkfs). Be nice and allow 90 * us to schedule out to avoid softlocking if preempt 91 * is disabled. 92 */ 93 cond_resched(); 94 } 95 96 *biop = bio; 97 return 0; 98 } 99 EXPORT_SYMBOL(__blkdev_issue_discard); 100 101 /** 102 * blkdev_issue_discard - queue a discard 103 * @bdev: blockdev to issue discard for 104 * @sector: start sector 105 * @nr_sects: number of sectors to discard 106 * @gfp_mask: memory allocation flags (for bio_alloc) 107 * @flags: BLKDEV_IFL_* flags to control behaviour 108 * 109 * Description: 110 * Issue a discard request for the sectors in question. 111 */ 112 int blkdev_issue_discard(struct block_device *bdev, sector_t sector, 113 sector_t nr_sects, gfp_t gfp_mask, unsigned long flags) 114 { 115 struct bio *bio = NULL; 116 struct blk_plug plug; 117 int ret; 118 119 blk_start_plug(&plug); 120 ret = __blkdev_issue_discard(bdev, sector, nr_sects, gfp_mask, flags, 121 &bio); 122 if (!ret && bio) { 123 ret = submit_bio_wait(bio); 124 if (ret == -EOPNOTSUPP && !(flags & BLKDEV_DISCARD_ZERO)) 125 ret = 0; 126 bio_put(bio); 127 } 128 blk_finish_plug(&plug); 129 130 return ret; 131 } 132 EXPORT_SYMBOL(blkdev_issue_discard); 133 134 /** 135 * blkdev_issue_write_same - queue a write same operation 136 * @bdev: target blockdev 137 * @sector: start sector 138 * @nr_sects: number of sectors to write 139 * @gfp_mask: memory allocation flags (for bio_alloc) 140 * @page: page containing data to write 141 * 142 * Description: 143 * Issue a write same request for the sectors in question. 144 */ 145 int blkdev_issue_write_same(struct block_device *bdev, sector_t sector, 146 sector_t nr_sects, gfp_t gfp_mask, 147 struct page *page) 148 { 149 struct request_queue *q = bdev_get_queue(bdev); 150 unsigned int max_write_same_sectors; 151 struct bio *bio = NULL; 152 int ret = 0; 153 154 if (!q) 155 return -ENXIO; 156 157 /* Ensure that max_write_same_sectors doesn't overflow bi_size */ 158 max_write_same_sectors = UINT_MAX >> 9; 159 160 while (nr_sects) { 161 bio = next_bio(bio, 1, gfp_mask); 162 bio->bi_iter.bi_sector = sector; 163 bio->bi_bdev = bdev; 164 bio->bi_vcnt = 1; 165 bio->bi_io_vec->bv_page = page; 166 bio->bi_io_vec->bv_offset = 0; 167 bio->bi_io_vec->bv_len = bdev_logical_block_size(bdev); 168 bio_set_op_attrs(bio, REQ_OP_WRITE_SAME, 0); 169 170 if (nr_sects > max_write_same_sectors) { 171 bio->bi_iter.bi_size = max_write_same_sectors << 9; 172 nr_sects -= max_write_same_sectors; 173 sector += max_write_same_sectors; 174 } else { 175 bio->bi_iter.bi_size = nr_sects << 9; 176 nr_sects = 0; 177 } 178 } 179 180 if (bio) { 181 ret = submit_bio_wait(bio); 182 bio_put(bio); 183 } 184 return ret; 185 } 186 EXPORT_SYMBOL(blkdev_issue_write_same); 187 188 /** 189 * blkdev_issue_zeroout - generate number of zero filed write bios 190 * @bdev: blockdev to issue 191 * @sector: start sector 192 * @nr_sects: number of sectors to write 193 * @gfp_mask: memory allocation flags (for bio_alloc) 194 * 195 * Description: 196 * Generate and issue number of bios with zerofiled pages. 197 */ 198 199 static int __blkdev_issue_zeroout(struct block_device *bdev, sector_t sector, 200 sector_t nr_sects, gfp_t gfp_mask) 201 { 202 int ret; 203 struct bio *bio = NULL; 204 unsigned int sz; 205 206 while (nr_sects != 0) { 207 bio = next_bio(bio, min(nr_sects, (sector_t)BIO_MAX_PAGES), 208 gfp_mask); 209 bio->bi_iter.bi_sector = sector; 210 bio->bi_bdev = bdev; 211 bio_set_op_attrs(bio, REQ_OP_WRITE, 0); 212 213 while (nr_sects != 0) { 214 sz = min((sector_t) PAGE_SIZE >> 9 , nr_sects); 215 ret = bio_add_page(bio, ZERO_PAGE(0), sz << 9, 0); 216 nr_sects -= ret >> 9; 217 sector += ret >> 9; 218 if (ret < (sz << 9)) 219 break; 220 } 221 } 222 223 if (bio) { 224 ret = submit_bio_wait(bio); 225 bio_put(bio); 226 return ret; 227 } 228 return 0; 229 } 230 231 /** 232 * blkdev_issue_zeroout - zero-fill a block range 233 * @bdev: blockdev to write 234 * @sector: start sector 235 * @nr_sects: number of sectors to write 236 * @gfp_mask: memory allocation flags (for bio_alloc) 237 * @discard: whether to discard the block range 238 * 239 * Description: 240 * Zero-fill a block range. If the discard flag is set and the block 241 * device guarantees that subsequent READ operations to the block range 242 * in question will return zeroes, the blocks will be discarded. Should 243 * the discard request fail, if the discard flag is not set, or if 244 * discard_zeroes_data is not supported, this function will resort to 245 * zeroing the blocks manually, thus provisioning (allocating, 246 * anchoring) them. If the block device supports the WRITE SAME command 247 * blkdev_issue_zeroout() will use it to optimize the process of 248 * clearing the block range. Otherwise the zeroing will be performed 249 * using regular WRITE calls. 250 */ 251 252 int blkdev_issue_zeroout(struct block_device *bdev, sector_t sector, 253 sector_t nr_sects, gfp_t gfp_mask, bool discard) 254 { 255 if (discard) { 256 if (!blkdev_issue_discard(bdev, sector, nr_sects, gfp_mask, 257 BLKDEV_DISCARD_ZERO)) 258 return 0; 259 } 260 261 if (bdev_write_same(bdev) && 262 blkdev_issue_write_same(bdev, sector, nr_sects, gfp_mask, 263 ZERO_PAGE(0)) == 0) 264 return 0; 265 266 return __blkdev_issue_zeroout(bdev, sector, nr_sects, gfp_mask); 267 } 268 EXPORT_SYMBOL(blkdev_issue_zeroout); 269