1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Functions related to setting various queue properties from drivers 4 */ 5 #include <linux/kernel.h> 6 #include <linux/module.h> 7 #include <linux/init.h> 8 #include <linux/bio.h> 9 #include <linux/blkdev.h> 10 #include <linux/memblock.h> /* for max_pfn/max_low_pfn */ 11 #include <linux/gcd.h> 12 #include <linux/lcm.h> 13 #include <linux/jiffies.h> 14 #include <linux/gfp.h> 15 16 #include "blk.h" 17 #include "blk-wbt.h" 18 19 unsigned long blk_max_low_pfn; 20 EXPORT_SYMBOL(blk_max_low_pfn); 21 22 unsigned long blk_max_pfn; 23 24 void blk_queue_rq_timeout(struct request_queue *q, unsigned int timeout) 25 { 26 q->rq_timeout = timeout; 27 } 28 EXPORT_SYMBOL_GPL(blk_queue_rq_timeout); 29 30 /** 31 * blk_set_default_limits - reset limits to default values 32 * @lim: the queue_limits structure to reset 33 * 34 * Description: 35 * Returns a queue_limit struct to its default state. 36 */ 37 void blk_set_default_limits(struct queue_limits *lim) 38 { 39 lim->max_segments = BLK_MAX_SEGMENTS; 40 lim->max_discard_segments = 1; 41 lim->max_integrity_segments = 0; 42 lim->seg_boundary_mask = BLK_SEG_BOUNDARY_MASK; 43 lim->virt_boundary_mask = 0; 44 lim->max_segment_size = BLK_MAX_SEGMENT_SIZE; 45 lim->max_sectors = lim->max_hw_sectors = BLK_SAFE_MAX_SECTORS; 46 lim->max_dev_sectors = 0; 47 lim->chunk_sectors = 0; 48 lim->max_write_same_sectors = 0; 49 lim->max_write_zeroes_sectors = 0; 50 lim->max_discard_sectors = 0; 51 lim->max_hw_discard_sectors = 0; 52 lim->discard_granularity = 0; 53 lim->discard_alignment = 0; 54 lim->discard_misaligned = 0; 55 lim->logical_block_size = lim->physical_block_size = lim->io_min = 512; 56 lim->bounce_pfn = (unsigned long)(BLK_BOUNCE_ANY >> PAGE_SHIFT); 57 lim->alignment_offset = 0; 58 lim->io_opt = 0; 59 lim->misaligned = 0; 60 lim->zoned = BLK_ZONED_NONE; 61 } 62 EXPORT_SYMBOL(blk_set_default_limits); 63 64 /** 65 * blk_set_stacking_limits - set default limits for stacking devices 66 * @lim: the queue_limits structure to reset 67 * 68 * Description: 69 * Returns a queue_limit struct to its default state. Should be used 70 * by stacking drivers like DM that have no internal limits. 71 */ 72 void blk_set_stacking_limits(struct queue_limits *lim) 73 { 74 blk_set_default_limits(lim); 75 76 /* Inherit limits from component devices */ 77 lim->max_segments = USHRT_MAX; 78 lim->max_discard_segments = USHRT_MAX; 79 lim->max_hw_sectors = UINT_MAX; 80 lim->max_segment_size = UINT_MAX; 81 lim->max_sectors = UINT_MAX; 82 lim->max_dev_sectors = UINT_MAX; 83 lim->max_write_same_sectors = UINT_MAX; 84 lim->max_write_zeroes_sectors = UINT_MAX; 85 } 86 EXPORT_SYMBOL(blk_set_stacking_limits); 87 88 /** 89 * blk_queue_make_request - define an alternate make_request function for a device 90 * @q: the request queue for the device to be affected 91 * @mfn: the alternate make_request function 92 * 93 * Description: 94 * The normal way for &struct bios to be passed to a device 95 * driver is for them to be collected into requests on a request 96 * queue, and then to allow the device driver to select requests 97 * off that queue when it is ready. This works well for many block 98 * devices. However some block devices (typically virtual devices 99 * such as md or lvm) do not benefit from the processing on the 100 * request queue, and are served best by having the requests passed 101 * directly to them. This can be achieved by providing a function 102 * to blk_queue_make_request(). 103 * 104 * Caveat: 105 * The driver that does this *must* be able to deal appropriately 106 * with buffers in "highmemory". This can be accomplished by either calling 107 * kmap_atomic() to get a temporary kernel mapping, or by calling 108 * blk_queue_bounce() to create a buffer in normal memory. 109 **/ 110 void blk_queue_make_request(struct request_queue *q, make_request_fn *mfn) 111 { 112 /* 113 * set defaults 114 */ 115 q->nr_requests = BLKDEV_MAX_RQ; 116 117 q->make_request_fn = mfn; 118 blk_queue_dma_alignment(q, 511); 119 120 blk_set_default_limits(&q->limits); 121 } 122 EXPORT_SYMBOL(blk_queue_make_request); 123 124 /** 125 * blk_queue_bounce_limit - set bounce buffer limit for queue 126 * @q: the request queue for the device 127 * @max_addr: the maximum address the device can handle 128 * 129 * Description: 130 * Different hardware can have different requirements as to what pages 131 * it can do I/O directly to. A low level driver can call 132 * blk_queue_bounce_limit to have lower memory pages allocated as bounce 133 * buffers for doing I/O to pages residing above @max_addr. 134 **/ 135 void blk_queue_bounce_limit(struct request_queue *q, u64 max_addr) 136 { 137 unsigned long b_pfn = max_addr >> PAGE_SHIFT; 138 int dma = 0; 139 140 q->bounce_gfp = GFP_NOIO; 141 #if BITS_PER_LONG == 64 142 /* 143 * Assume anything <= 4GB can be handled by IOMMU. Actually 144 * some IOMMUs can handle everything, but I don't know of a 145 * way to test this here. 146 */ 147 if (b_pfn < (min_t(u64, 0xffffffffUL, BLK_BOUNCE_HIGH) >> PAGE_SHIFT)) 148 dma = 1; 149 q->limits.bounce_pfn = max(max_low_pfn, b_pfn); 150 #else 151 if (b_pfn < blk_max_low_pfn) 152 dma = 1; 153 q->limits.bounce_pfn = b_pfn; 154 #endif 155 if (dma) { 156 init_emergency_isa_pool(); 157 q->bounce_gfp = GFP_NOIO | GFP_DMA; 158 q->limits.bounce_pfn = b_pfn; 159 } 160 } 161 EXPORT_SYMBOL(blk_queue_bounce_limit); 162 163 /** 164 * blk_queue_max_hw_sectors - set max sectors for a request for this queue 165 * @q: the request queue for the device 166 * @max_hw_sectors: max hardware sectors in the usual 512b unit 167 * 168 * Description: 169 * Enables a low level driver to set a hard upper limit, 170 * max_hw_sectors, on the size of requests. max_hw_sectors is set by 171 * the device driver based upon the capabilities of the I/O 172 * controller. 173 * 174 * max_dev_sectors is a hard limit imposed by the storage device for 175 * READ/WRITE requests. It is set by the disk driver. 176 * 177 * max_sectors is a soft limit imposed by the block layer for 178 * filesystem type requests. This value can be overridden on a 179 * per-device basis in /sys/block/<device>/queue/max_sectors_kb. 180 * The soft limit can not exceed max_hw_sectors. 181 **/ 182 void blk_queue_max_hw_sectors(struct request_queue *q, unsigned int max_hw_sectors) 183 { 184 struct queue_limits *limits = &q->limits; 185 unsigned int max_sectors; 186 187 if ((max_hw_sectors << 9) < PAGE_SIZE) { 188 max_hw_sectors = 1 << (PAGE_SHIFT - 9); 189 printk(KERN_INFO "%s: set to minimum %d\n", 190 __func__, max_hw_sectors); 191 } 192 193 limits->max_hw_sectors = max_hw_sectors; 194 max_sectors = min_not_zero(max_hw_sectors, limits->max_dev_sectors); 195 max_sectors = min_t(unsigned int, max_sectors, BLK_DEF_MAX_SECTORS); 196 limits->max_sectors = max_sectors; 197 q->backing_dev_info->io_pages = max_sectors >> (PAGE_SHIFT - 9); 198 } 199 EXPORT_SYMBOL(blk_queue_max_hw_sectors); 200 201 /** 202 * blk_queue_chunk_sectors - set size of the chunk for this queue 203 * @q: the request queue for the device 204 * @chunk_sectors: chunk sectors in the usual 512b unit 205 * 206 * Description: 207 * If a driver doesn't want IOs to cross a given chunk size, it can set 208 * this limit and prevent merging across chunks. Note that the chunk size 209 * must currently be a power-of-2 in sectors. Also note that the block 210 * layer must accept a page worth of data at any offset. So if the 211 * crossing of chunks is a hard limitation in the driver, it must still be 212 * prepared to split single page bios. 213 **/ 214 void blk_queue_chunk_sectors(struct request_queue *q, unsigned int chunk_sectors) 215 { 216 BUG_ON(!is_power_of_2(chunk_sectors)); 217 q->limits.chunk_sectors = chunk_sectors; 218 } 219 EXPORT_SYMBOL(blk_queue_chunk_sectors); 220 221 /** 222 * blk_queue_max_discard_sectors - set max sectors for a single discard 223 * @q: the request queue for the device 224 * @max_discard_sectors: maximum number of sectors to discard 225 **/ 226 void blk_queue_max_discard_sectors(struct request_queue *q, 227 unsigned int max_discard_sectors) 228 { 229 q->limits.max_hw_discard_sectors = max_discard_sectors; 230 q->limits.max_discard_sectors = max_discard_sectors; 231 } 232 EXPORT_SYMBOL(blk_queue_max_discard_sectors); 233 234 /** 235 * blk_queue_max_write_same_sectors - set max sectors for a single write same 236 * @q: the request queue for the device 237 * @max_write_same_sectors: maximum number of sectors to write per command 238 **/ 239 void blk_queue_max_write_same_sectors(struct request_queue *q, 240 unsigned int max_write_same_sectors) 241 { 242 q->limits.max_write_same_sectors = max_write_same_sectors; 243 } 244 EXPORT_SYMBOL(blk_queue_max_write_same_sectors); 245 246 /** 247 * blk_queue_max_write_zeroes_sectors - set max sectors for a single 248 * write zeroes 249 * @q: the request queue for the device 250 * @max_write_zeroes_sectors: maximum number of sectors to write per command 251 **/ 252 void blk_queue_max_write_zeroes_sectors(struct request_queue *q, 253 unsigned int max_write_zeroes_sectors) 254 { 255 q->limits.max_write_zeroes_sectors = max_write_zeroes_sectors; 256 } 257 EXPORT_SYMBOL(blk_queue_max_write_zeroes_sectors); 258 259 /** 260 * blk_queue_max_segments - set max hw segments for a request for this queue 261 * @q: the request queue for the device 262 * @max_segments: max number of segments 263 * 264 * Description: 265 * Enables a low level driver to set an upper limit on the number of 266 * hw data segments in a request. 267 **/ 268 void blk_queue_max_segments(struct request_queue *q, unsigned short max_segments) 269 { 270 if (!max_segments) { 271 max_segments = 1; 272 printk(KERN_INFO "%s: set to minimum %d\n", 273 __func__, max_segments); 274 } 275 276 q->limits.max_segments = max_segments; 277 } 278 EXPORT_SYMBOL(blk_queue_max_segments); 279 280 /** 281 * blk_queue_max_discard_segments - set max segments for discard requests 282 * @q: the request queue for the device 283 * @max_segments: max number of segments 284 * 285 * Description: 286 * Enables a low level driver to set an upper limit on the number of 287 * segments in a discard request. 288 **/ 289 void blk_queue_max_discard_segments(struct request_queue *q, 290 unsigned short max_segments) 291 { 292 q->limits.max_discard_segments = max_segments; 293 } 294 EXPORT_SYMBOL_GPL(blk_queue_max_discard_segments); 295 296 /** 297 * blk_queue_max_segment_size - set max segment size for blk_rq_map_sg 298 * @q: the request queue for the device 299 * @max_size: max size of segment in bytes 300 * 301 * Description: 302 * Enables a low level driver to set an upper limit on the size of a 303 * coalesced segment 304 **/ 305 void blk_queue_max_segment_size(struct request_queue *q, unsigned int max_size) 306 { 307 if (max_size < PAGE_SIZE) { 308 max_size = PAGE_SIZE; 309 printk(KERN_INFO "%s: set to minimum %d\n", 310 __func__, max_size); 311 } 312 313 /* see blk_queue_virt_boundary() for the explanation */ 314 WARN_ON_ONCE(q->limits.virt_boundary_mask); 315 316 q->limits.max_segment_size = max_size; 317 } 318 EXPORT_SYMBOL(blk_queue_max_segment_size); 319 320 /** 321 * blk_queue_logical_block_size - set logical block size for the queue 322 * @q: the request queue for the device 323 * @size: the logical block size, in bytes 324 * 325 * Description: 326 * This should be set to the lowest possible block size that the 327 * storage device can address. The default of 512 covers most 328 * hardware. 329 **/ 330 void blk_queue_logical_block_size(struct request_queue *q, unsigned short size) 331 { 332 q->limits.logical_block_size = size; 333 334 if (q->limits.physical_block_size < size) 335 q->limits.physical_block_size = size; 336 337 if (q->limits.io_min < q->limits.physical_block_size) 338 q->limits.io_min = q->limits.physical_block_size; 339 } 340 EXPORT_SYMBOL(blk_queue_logical_block_size); 341 342 /** 343 * blk_queue_physical_block_size - set physical block size for the queue 344 * @q: the request queue for the device 345 * @size: the physical block size, in bytes 346 * 347 * Description: 348 * This should be set to the lowest possible sector size that the 349 * hardware can operate on without reverting to read-modify-write 350 * operations. 351 */ 352 void blk_queue_physical_block_size(struct request_queue *q, unsigned int size) 353 { 354 q->limits.physical_block_size = size; 355 356 if (q->limits.physical_block_size < q->limits.logical_block_size) 357 q->limits.physical_block_size = q->limits.logical_block_size; 358 359 if (q->limits.io_min < q->limits.physical_block_size) 360 q->limits.io_min = q->limits.physical_block_size; 361 } 362 EXPORT_SYMBOL(blk_queue_physical_block_size); 363 364 /** 365 * blk_queue_alignment_offset - set physical block alignment offset 366 * @q: the request queue for the device 367 * @offset: alignment offset in bytes 368 * 369 * Description: 370 * Some devices are naturally misaligned to compensate for things like 371 * the legacy DOS partition table 63-sector offset. Low-level drivers 372 * should call this function for devices whose first sector is not 373 * naturally aligned. 374 */ 375 void blk_queue_alignment_offset(struct request_queue *q, unsigned int offset) 376 { 377 q->limits.alignment_offset = 378 offset & (q->limits.physical_block_size - 1); 379 q->limits.misaligned = 0; 380 } 381 EXPORT_SYMBOL(blk_queue_alignment_offset); 382 383 /** 384 * blk_limits_io_min - set minimum request size for a device 385 * @limits: the queue limits 386 * @min: smallest I/O size in bytes 387 * 388 * Description: 389 * Some devices have an internal block size bigger than the reported 390 * hardware sector size. This function can be used to signal the 391 * smallest I/O the device can perform without incurring a performance 392 * penalty. 393 */ 394 void blk_limits_io_min(struct queue_limits *limits, unsigned int min) 395 { 396 limits->io_min = min; 397 398 if (limits->io_min < limits->logical_block_size) 399 limits->io_min = limits->logical_block_size; 400 401 if (limits->io_min < limits->physical_block_size) 402 limits->io_min = limits->physical_block_size; 403 } 404 EXPORT_SYMBOL(blk_limits_io_min); 405 406 /** 407 * blk_queue_io_min - set minimum request size for the queue 408 * @q: the request queue for the device 409 * @min: smallest I/O size in bytes 410 * 411 * Description: 412 * Storage devices may report a granularity or preferred minimum I/O 413 * size which is the smallest request the device can perform without 414 * incurring a performance penalty. For disk drives this is often the 415 * physical block size. For RAID arrays it is often the stripe chunk 416 * size. A properly aligned multiple of minimum_io_size is the 417 * preferred request size for workloads where a high number of I/O 418 * operations is desired. 419 */ 420 void blk_queue_io_min(struct request_queue *q, unsigned int min) 421 { 422 blk_limits_io_min(&q->limits, min); 423 } 424 EXPORT_SYMBOL(blk_queue_io_min); 425 426 /** 427 * blk_limits_io_opt - set optimal request size for a device 428 * @limits: the queue limits 429 * @opt: smallest I/O size in bytes 430 * 431 * Description: 432 * Storage devices may report an optimal I/O size, which is the 433 * device's preferred unit for sustained I/O. This is rarely reported 434 * for disk drives. For RAID arrays it is usually the stripe width or 435 * the internal track size. A properly aligned multiple of 436 * optimal_io_size is the preferred request size for workloads where 437 * sustained throughput is desired. 438 */ 439 void blk_limits_io_opt(struct queue_limits *limits, unsigned int opt) 440 { 441 limits->io_opt = opt; 442 } 443 EXPORT_SYMBOL(blk_limits_io_opt); 444 445 /** 446 * blk_queue_io_opt - set optimal request size for the queue 447 * @q: the request queue for the device 448 * @opt: optimal request size in bytes 449 * 450 * Description: 451 * Storage devices may report an optimal I/O size, which is the 452 * device's preferred unit for sustained I/O. This is rarely reported 453 * for disk drives. For RAID arrays it is usually the stripe width or 454 * the internal track size. A properly aligned multiple of 455 * optimal_io_size is the preferred request size for workloads where 456 * sustained throughput is desired. 457 */ 458 void blk_queue_io_opt(struct request_queue *q, unsigned int opt) 459 { 460 blk_limits_io_opt(&q->limits, opt); 461 } 462 EXPORT_SYMBOL(blk_queue_io_opt); 463 464 /** 465 * blk_queue_stack_limits - inherit underlying queue limits for stacked drivers 466 * @t: the stacking driver (top) 467 * @b: the underlying device (bottom) 468 **/ 469 void blk_queue_stack_limits(struct request_queue *t, struct request_queue *b) 470 { 471 blk_stack_limits(&t->limits, &b->limits, 0); 472 } 473 EXPORT_SYMBOL(blk_queue_stack_limits); 474 475 /** 476 * blk_stack_limits - adjust queue_limits for stacked devices 477 * @t: the stacking driver limits (top device) 478 * @b: the underlying queue limits (bottom, component device) 479 * @start: first data sector within component device 480 * 481 * Description: 482 * This function is used by stacking drivers like MD and DM to ensure 483 * that all component devices have compatible block sizes and 484 * alignments. The stacking driver must provide a queue_limits 485 * struct (top) and then iteratively call the stacking function for 486 * all component (bottom) devices. The stacking function will 487 * attempt to combine the values and ensure proper alignment. 488 * 489 * Returns 0 if the top and bottom queue_limits are compatible. The 490 * top device's block sizes and alignment offsets may be adjusted to 491 * ensure alignment with the bottom device. If no compatible sizes 492 * and alignments exist, -1 is returned and the resulting top 493 * queue_limits will have the misaligned flag set to indicate that 494 * the alignment_offset is undefined. 495 */ 496 int blk_stack_limits(struct queue_limits *t, struct queue_limits *b, 497 sector_t start) 498 { 499 unsigned int top, bottom, alignment, ret = 0; 500 501 t->max_sectors = min_not_zero(t->max_sectors, b->max_sectors); 502 t->max_hw_sectors = min_not_zero(t->max_hw_sectors, b->max_hw_sectors); 503 t->max_dev_sectors = min_not_zero(t->max_dev_sectors, b->max_dev_sectors); 504 t->max_write_same_sectors = min(t->max_write_same_sectors, 505 b->max_write_same_sectors); 506 t->max_write_zeroes_sectors = min(t->max_write_zeroes_sectors, 507 b->max_write_zeroes_sectors); 508 t->bounce_pfn = min_not_zero(t->bounce_pfn, b->bounce_pfn); 509 510 t->seg_boundary_mask = min_not_zero(t->seg_boundary_mask, 511 b->seg_boundary_mask); 512 t->virt_boundary_mask = min_not_zero(t->virt_boundary_mask, 513 b->virt_boundary_mask); 514 515 t->max_segments = min_not_zero(t->max_segments, b->max_segments); 516 t->max_discard_segments = min_not_zero(t->max_discard_segments, 517 b->max_discard_segments); 518 t->max_integrity_segments = min_not_zero(t->max_integrity_segments, 519 b->max_integrity_segments); 520 521 t->max_segment_size = min_not_zero(t->max_segment_size, 522 b->max_segment_size); 523 524 t->misaligned |= b->misaligned; 525 526 alignment = queue_limit_alignment_offset(b, start); 527 528 /* Bottom device has different alignment. Check that it is 529 * compatible with the current top alignment. 530 */ 531 if (t->alignment_offset != alignment) { 532 533 top = max(t->physical_block_size, t->io_min) 534 + t->alignment_offset; 535 bottom = max(b->physical_block_size, b->io_min) + alignment; 536 537 /* Verify that top and bottom intervals line up */ 538 if (max(top, bottom) % min(top, bottom)) { 539 t->misaligned = 1; 540 ret = -1; 541 } 542 } 543 544 t->logical_block_size = max(t->logical_block_size, 545 b->logical_block_size); 546 547 t->physical_block_size = max(t->physical_block_size, 548 b->physical_block_size); 549 550 t->io_min = max(t->io_min, b->io_min); 551 t->io_opt = lcm_not_zero(t->io_opt, b->io_opt); 552 553 /* Physical block size a multiple of the logical block size? */ 554 if (t->physical_block_size & (t->logical_block_size - 1)) { 555 t->physical_block_size = t->logical_block_size; 556 t->misaligned = 1; 557 ret = -1; 558 } 559 560 /* Minimum I/O a multiple of the physical block size? */ 561 if (t->io_min & (t->physical_block_size - 1)) { 562 t->io_min = t->physical_block_size; 563 t->misaligned = 1; 564 ret = -1; 565 } 566 567 /* Optimal I/O a multiple of the physical block size? */ 568 if (t->io_opt & (t->physical_block_size - 1)) { 569 t->io_opt = 0; 570 t->misaligned = 1; 571 ret = -1; 572 } 573 574 t->raid_partial_stripes_expensive = 575 max(t->raid_partial_stripes_expensive, 576 b->raid_partial_stripes_expensive); 577 578 /* Find lowest common alignment_offset */ 579 t->alignment_offset = lcm_not_zero(t->alignment_offset, alignment) 580 % max(t->physical_block_size, t->io_min); 581 582 /* Verify that new alignment_offset is on a logical block boundary */ 583 if (t->alignment_offset & (t->logical_block_size - 1)) { 584 t->misaligned = 1; 585 ret = -1; 586 } 587 588 /* Discard alignment and granularity */ 589 if (b->discard_granularity) { 590 alignment = queue_limit_discard_alignment(b, start); 591 592 if (t->discard_granularity != 0 && 593 t->discard_alignment != alignment) { 594 top = t->discard_granularity + t->discard_alignment; 595 bottom = b->discard_granularity + alignment; 596 597 /* Verify that top and bottom intervals line up */ 598 if ((max(top, bottom) % min(top, bottom)) != 0) 599 t->discard_misaligned = 1; 600 } 601 602 t->max_discard_sectors = min_not_zero(t->max_discard_sectors, 603 b->max_discard_sectors); 604 t->max_hw_discard_sectors = min_not_zero(t->max_hw_discard_sectors, 605 b->max_hw_discard_sectors); 606 t->discard_granularity = max(t->discard_granularity, 607 b->discard_granularity); 608 t->discard_alignment = lcm_not_zero(t->discard_alignment, alignment) % 609 t->discard_granularity; 610 } 611 612 if (b->chunk_sectors) 613 t->chunk_sectors = min_not_zero(t->chunk_sectors, 614 b->chunk_sectors); 615 616 return ret; 617 } 618 EXPORT_SYMBOL(blk_stack_limits); 619 620 /** 621 * bdev_stack_limits - adjust queue limits for stacked drivers 622 * @t: the stacking driver limits (top device) 623 * @bdev: the component block_device (bottom) 624 * @start: first data sector within component device 625 * 626 * Description: 627 * Merges queue limits for a top device and a block_device. Returns 628 * 0 if alignment didn't change. Returns -1 if adding the bottom 629 * device caused misalignment. 630 */ 631 int bdev_stack_limits(struct queue_limits *t, struct block_device *bdev, 632 sector_t start) 633 { 634 struct request_queue *bq = bdev_get_queue(bdev); 635 636 start += get_start_sect(bdev); 637 638 return blk_stack_limits(t, &bq->limits, start); 639 } 640 EXPORT_SYMBOL(bdev_stack_limits); 641 642 /** 643 * disk_stack_limits - adjust queue limits for stacked drivers 644 * @disk: MD/DM gendisk (top) 645 * @bdev: the underlying block device (bottom) 646 * @offset: offset to beginning of data within component device 647 * 648 * Description: 649 * Merges the limits for a top level gendisk and a bottom level 650 * block_device. 651 */ 652 void disk_stack_limits(struct gendisk *disk, struct block_device *bdev, 653 sector_t offset) 654 { 655 struct request_queue *t = disk->queue; 656 657 if (bdev_stack_limits(&t->limits, bdev, offset >> 9) < 0) { 658 char top[BDEVNAME_SIZE], bottom[BDEVNAME_SIZE]; 659 660 disk_name(disk, 0, top); 661 bdevname(bdev, bottom); 662 663 printk(KERN_NOTICE "%s: Warning: Device %s is misaligned\n", 664 top, bottom); 665 } 666 } 667 EXPORT_SYMBOL(disk_stack_limits); 668 669 /** 670 * blk_queue_update_dma_pad - update pad mask 671 * @q: the request queue for the device 672 * @mask: pad mask 673 * 674 * Update dma pad mask. 675 * 676 * Appending pad buffer to a request modifies the last entry of a 677 * scatter list such that it includes the pad buffer. 678 **/ 679 void blk_queue_update_dma_pad(struct request_queue *q, unsigned int mask) 680 { 681 if (mask > q->dma_pad_mask) 682 q->dma_pad_mask = mask; 683 } 684 EXPORT_SYMBOL(blk_queue_update_dma_pad); 685 686 /** 687 * blk_queue_dma_drain - Set up a drain buffer for excess dma. 688 * @q: the request queue for the device 689 * @dma_drain_needed: fn which returns non-zero if drain is necessary 690 * @buf: physically contiguous buffer 691 * @size: size of the buffer in bytes 692 * 693 * Some devices have excess DMA problems and can't simply discard (or 694 * zero fill) the unwanted piece of the transfer. They have to have a 695 * real area of memory to transfer it into. The use case for this is 696 * ATAPI devices in DMA mode. If the packet command causes a transfer 697 * bigger than the transfer size some HBAs will lock up if there 698 * aren't DMA elements to contain the excess transfer. What this API 699 * does is adjust the queue so that the buf is always appended 700 * silently to the scatterlist. 701 * 702 * Note: This routine adjusts max_hw_segments to make room for appending 703 * the drain buffer. If you call blk_queue_max_segments() after calling 704 * this routine, you must set the limit to one fewer than your device 705 * can support otherwise there won't be room for the drain buffer. 706 */ 707 int blk_queue_dma_drain(struct request_queue *q, 708 dma_drain_needed_fn *dma_drain_needed, 709 void *buf, unsigned int size) 710 { 711 if (queue_max_segments(q) < 2) 712 return -EINVAL; 713 /* make room for appending the drain */ 714 blk_queue_max_segments(q, queue_max_segments(q) - 1); 715 q->dma_drain_needed = dma_drain_needed; 716 q->dma_drain_buffer = buf; 717 q->dma_drain_size = size; 718 719 return 0; 720 } 721 EXPORT_SYMBOL_GPL(blk_queue_dma_drain); 722 723 /** 724 * blk_queue_segment_boundary - set boundary rules for segment merging 725 * @q: the request queue for the device 726 * @mask: the memory boundary mask 727 **/ 728 void blk_queue_segment_boundary(struct request_queue *q, unsigned long mask) 729 { 730 if (mask < PAGE_SIZE - 1) { 731 mask = PAGE_SIZE - 1; 732 printk(KERN_INFO "%s: set to minimum %lx\n", 733 __func__, mask); 734 } 735 736 q->limits.seg_boundary_mask = mask; 737 } 738 EXPORT_SYMBOL(blk_queue_segment_boundary); 739 740 /** 741 * blk_queue_virt_boundary - set boundary rules for bio merging 742 * @q: the request queue for the device 743 * @mask: the memory boundary mask 744 **/ 745 void blk_queue_virt_boundary(struct request_queue *q, unsigned long mask) 746 { 747 q->limits.virt_boundary_mask = mask; 748 749 /* 750 * Devices that require a virtual boundary do not support scatter/gather 751 * I/O natively, but instead require a descriptor list entry for each 752 * page (which might not be idential to the Linux PAGE_SIZE). Because 753 * of that they are not limited by our notion of "segment size". 754 */ 755 q->limits.max_segment_size = UINT_MAX; 756 } 757 EXPORT_SYMBOL(blk_queue_virt_boundary); 758 759 /** 760 * blk_queue_dma_alignment - set dma length and memory alignment 761 * @q: the request queue for the device 762 * @mask: alignment mask 763 * 764 * description: 765 * set required memory and length alignment for direct dma transactions. 766 * this is used when building direct io requests for the queue. 767 * 768 **/ 769 void blk_queue_dma_alignment(struct request_queue *q, int mask) 770 { 771 q->dma_alignment = mask; 772 } 773 EXPORT_SYMBOL(blk_queue_dma_alignment); 774 775 /** 776 * blk_queue_update_dma_alignment - update dma length and memory alignment 777 * @q: the request queue for the device 778 * @mask: alignment mask 779 * 780 * description: 781 * update required memory and length alignment for direct dma transactions. 782 * If the requested alignment is larger than the current alignment, then 783 * the current queue alignment is updated to the new value, otherwise it 784 * is left alone. The design of this is to allow multiple objects 785 * (driver, device, transport etc) to set their respective 786 * alignments without having them interfere. 787 * 788 **/ 789 void blk_queue_update_dma_alignment(struct request_queue *q, int mask) 790 { 791 BUG_ON(mask > PAGE_SIZE); 792 793 if (mask > q->dma_alignment) 794 q->dma_alignment = mask; 795 } 796 EXPORT_SYMBOL(blk_queue_update_dma_alignment); 797 798 /** 799 * blk_set_queue_depth - tell the block layer about the device queue depth 800 * @q: the request queue for the device 801 * @depth: queue depth 802 * 803 */ 804 void blk_set_queue_depth(struct request_queue *q, unsigned int depth) 805 { 806 q->queue_depth = depth; 807 wbt_set_queue_depth(q, depth); 808 } 809 EXPORT_SYMBOL(blk_set_queue_depth); 810 811 /** 812 * blk_queue_write_cache - configure queue's write cache 813 * @q: the request queue for the device 814 * @wc: write back cache on or off 815 * @fua: device supports FUA writes, if true 816 * 817 * Tell the block layer about the write cache of @q. 818 */ 819 void blk_queue_write_cache(struct request_queue *q, bool wc, bool fua) 820 { 821 if (wc) 822 blk_queue_flag_set(QUEUE_FLAG_WC, q); 823 else 824 blk_queue_flag_clear(QUEUE_FLAG_WC, q); 825 if (fua) 826 blk_queue_flag_set(QUEUE_FLAG_FUA, q); 827 else 828 blk_queue_flag_clear(QUEUE_FLAG_FUA, q); 829 830 wbt_set_write_cache(q, test_bit(QUEUE_FLAG_WC, &q->queue_flags)); 831 } 832 EXPORT_SYMBOL_GPL(blk_queue_write_cache); 833 834 static int __init blk_settings_init(void) 835 { 836 blk_max_low_pfn = max_low_pfn - 1; 837 blk_max_pfn = max_pfn - 1; 838 return 0; 839 } 840 subsys_initcall(blk_settings_init); 841