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); 252