1 /* 2 * Functions related to setting various queue properties from drivers 3 */ 4 #include <linux/kernel.h> 5 #include <linux/module.h> 6 #include <linux/init.h> 7 #include <linux/bio.h> 8 #include <linux/blkdev.h> 9 #include <linux/memblock.h> /* for max_pfn/max_low_pfn */ 10 #include <linux/gcd.h> 11 #include <linux/lcm.h> 12 #include <linux/jiffies.h> 13 #include <linux/gfp.h> 14 15 #include "blk.h" 16 #include "blk-wbt.h" 17 18 unsigned long blk_max_low_pfn; 19 EXPORT_SYMBOL(blk_max_low_pfn); 20 21 unsigned long blk_max_pfn; 22 23 void blk_queue_rq_timeout(struct request_queue *q, unsigned int timeout) 24 { 25 q->rq_timeout = timeout; 26 } 27 EXPORT_SYMBOL_GPL(blk_queue_rq_timeout); 28 29 /** 30 * blk_set_default_limits - reset limits to default values 31 * @lim: the queue_limits structure to reset 32 * 33 * Description: 34 * Returns a queue_limit struct to its default state. 35 */ 36 void blk_set_default_limits(struct queue_limits *lim) 37 { 38 lim->max_segments = BLK_MAX_SEGMENTS; 39 lim->max_discard_segments = 1; 40 lim->max_integrity_segments = 0; 41 lim->seg_boundary_mask = BLK_SEG_BOUNDARY_MASK; 42 lim->virt_boundary_mask = 0; 43 lim->max_segment_size = BLK_MAX_SEGMENT_SIZE; 44 lim->max_sectors = lim->max_hw_sectors = BLK_SAFE_MAX_SECTORS; 45 lim->max_dev_sectors = 0; 46 lim->chunk_sectors = 0; 47 lim->max_write_same_sectors = 0; 48 lim->max_write_zeroes_sectors = 0; 49 lim->max_discard_sectors = 0; 50 lim->max_hw_discard_sectors = 0; 51 lim->discard_granularity = 0; 52 lim->discard_alignment = 0; 53 lim->discard_misaligned = 0; 54 lim->logical_block_size = lim->physical_block_size = lim->io_min = 512; 55 lim->bounce_pfn = (unsigned long)(BLK_BOUNCE_ANY >> PAGE_SHIFT); 56 lim->alignment_offset = 0; 57 lim->io_opt = 0; 58 lim->misaligned = 0; 59 lim->zoned = BLK_ZONED_NONE; 60 } 61 EXPORT_SYMBOL(blk_set_default_limits); 62 63 /** 64 * blk_set_stacking_limits - set default limits for stacking devices 65 * @lim: the queue_limits structure to reset 66 * 67 * Description: 68 * Returns a queue_limit struct to its default state. Should be used 69 * by stacking drivers like DM that have no internal limits. 70 */ 71 void blk_set_stacking_limits(struct queue_limits *lim) 72 { 73 blk_set_default_limits(lim); 74 75 /* Inherit limits from component devices */ 76 lim->max_segments = USHRT_MAX; 77 lim->max_discard_segments = USHRT_MAX; 78 lim->max_hw_sectors = UINT_MAX; 79 lim->max_segment_size = UINT_MAX; 80 lim->max_sectors = UINT_MAX; 81 lim->max_dev_sectors = UINT_MAX; 82 lim->max_write_same_sectors = UINT_MAX; 83 lim->max_write_zeroes_sectors = UINT_MAX; 84 } 85 EXPORT_SYMBOL(blk_set_stacking_limits); 86 87 /** 88 * blk_queue_make_request - define an alternate make_request function for a device 89 * @q: the request queue for the device to be affected 90 * @mfn: the alternate make_request function 91 * 92 * Description: 93 * The normal way for &struct bios to be passed to a device 94 * driver is for them to be collected into requests on a request 95 * queue, and then to allow the device driver to select requests 96 * off that queue when it is ready. This works well for many block 97 * devices. However some block devices (typically virtual devices 98 * such as md or lvm) do not benefit from the processing on the 99 * request queue, and are served best by having the requests passed 100 * directly to them. This can be achieved by providing a function 101 * to blk_queue_make_request(). 102 * 103 * Caveat: 104 * The driver that does this *must* be able to deal appropriately 105 * with buffers in "highmemory". This can be accomplished by either calling 106 * kmap_atomic() to get a temporary kernel mapping, or by calling 107 * blk_queue_bounce() to create a buffer in normal memory. 108 **/ 109 void blk_queue_make_request(struct request_queue *q, make_request_fn *mfn) 110 { 111 /* 112 * set defaults 113 */ 114 q->nr_requests = BLKDEV_MAX_RQ; 115 116 q->make_request_fn = mfn; 117 blk_queue_dma_alignment(q, 511); 118 119 blk_set_default_limits(&q->limits); 120 } 121 EXPORT_SYMBOL(blk_queue_make_request); 122 123 /** 124 * blk_queue_bounce_limit - set bounce buffer limit for queue 125 * @q: the request queue for the device 126 * @max_addr: the maximum address the device can handle 127 * 128 * Description: 129 * Different hardware can have different requirements as to what pages 130 * it can do I/O directly to. A low level driver can call 131 * blk_queue_bounce_limit to have lower memory pages allocated as bounce 132 * buffers for doing I/O to pages residing above @max_addr. 133 **/ 134 void blk_queue_bounce_limit(struct request_queue *q, u64 max_addr) 135 { 136 unsigned long b_pfn = max_addr >> PAGE_SHIFT; 137 int dma = 0; 138 139 q->bounce_gfp = GFP_NOIO; 140 #if BITS_PER_LONG == 64 141 /* 142 * Assume anything <= 4GB can be handled by IOMMU. Actually 143 * some IOMMUs can handle everything, but I don't know of a 144 * way to test this here. 145 */ 146 if (b_pfn < (min_t(u64, 0xffffffffUL, BLK_BOUNCE_HIGH) >> PAGE_SHIFT)) 147 dma = 1; 148 q->limits.bounce_pfn = max(max_low_pfn, b_pfn); 149 #else 150 if (b_pfn < blk_max_low_pfn) 151 dma = 1; 152 q->limits.bounce_pfn = b_pfn; 153 #endif 154 if (dma) { 155 init_emergency_isa_pool(); 156 q->bounce_gfp = GFP_NOIO | GFP_DMA; 157 q->limits.bounce_pfn = b_pfn; 158 } 159 } 160 EXPORT_SYMBOL(blk_queue_bounce_limit); 161 162 /** 163 * blk_queue_max_hw_sectors - set max sectors for a request for this queue 164 * @q: the request queue for the device 165 * @max_hw_sectors: max hardware sectors in the usual 512b unit 166 * 167 * Description: 168 * Enables a low level driver to set a hard upper limit, 169 * max_hw_sectors, on the size of requests. max_hw_sectors is set by 170 * the device driver based upon the capabilities of the I/O 171 * controller. 172 * 173 * max_dev_sectors is a hard limit imposed by the storage device for 174 * READ/WRITE requests. It is set by the disk driver. 175 * 176 * max_sectors is a soft limit imposed by the block layer for 177 * filesystem type requests. This value can be overridden on a 178 * per-device basis in /sys/block/<device>/queue/max_sectors_kb. 179 * The soft limit can not exceed max_hw_sectors. 180 **/ 181 void blk_queue_max_hw_sectors(struct request_queue *q, unsigned int max_hw_sectors) 182 { 183 struct queue_limits *limits = &q->limits; 184 unsigned int max_sectors; 185 186 if ((max_hw_sectors << 9) < PAGE_SIZE) { 187 max_hw_sectors = 1 << (PAGE_SHIFT - 9); 188 printk(KERN_INFO "%s: set to minimum %d\n", 189 __func__, max_hw_sectors); 190 } 191 192 limits->max_hw_sectors = max_hw_sectors; 193 max_sectors = min_not_zero(max_hw_sectors, limits->max_dev_sectors); 194 max_sectors = min_t(unsigned int, max_sectors, BLK_DEF_MAX_SECTORS); 195 limits->max_sectors = max_sectors; 196 q->backing_dev_info->io_pages = max_sectors >> (PAGE_SHIFT - 9); 197 } 198 EXPORT_SYMBOL(blk_queue_max_hw_sectors); 199 200 /** 201 * blk_queue_chunk_sectors - set size of the chunk for this queue 202 * @q: the request queue for the device 203 * @chunk_sectors: chunk sectors in the usual 512b unit 204 * 205 * Description: 206 * If a driver doesn't want IOs to cross a given chunk size, it can set 207 * this limit and prevent merging across chunks. Note that the chunk size 208 * must currently be a power-of-2 in sectors. Also note that the block 209 * layer must accept a page worth of data at any offset. So if the 210 * crossing of chunks is a hard limitation in the driver, it must still be 211 * prepared to split single page bios. 212 **/ 213 void blk_queue_chunk_sectors(struct request_queue *q, unsigned int chunk_sectors) 214 { 215 BUG_ON(!is_power_of_2(chunk_sectors)); 216 q->limits.chunk_sectors = chunk_sectors; 217 } 218 EXPORT_SYMBOL(blk_queue_chunk_sectors); 219 220 /** 221 * blk_queue_max_discard_sectors - set max sectors for a single discard 222 * @q: the request queue for the device 223 * @max_discard_sectors: maximum number of sectors to discard 224 **/ 225 void blk_queue_max_discard_sectors(struct request_queue *q, 226 unsigned int max_discard_sectors) 227 { 228 q->limits.max_hw_discard_sectors = max_discard_sectors; 229 q->limits.max_discard_sectors = max_discard_sectors; 230 } 231 EXPORT_SYMBOL(blk_queue_max_discard_sectors); 232 233 /** 234 * blk_queue_max_write_same_sectors - set max sectors for a single write same 235 * @q: the request queue for the device 236 * @max_write_same_sectors: maximum number of sectors to write per command 237 **/ 238 void blk_queue_max_write_same_sectors(struct request_queue *q, 239 unsigned int max_write_same_sectors) 240 { 241 q->limits.max_write_same_sectors = max_write_same_sectors; 242 } 243 EXPORT_SYMBOL(blk_queue_max_write_same_sectors); 244 245 /** 246 * blk_queue_max_write_zeroes_sectors - set max sectors for a single 247 * write zeroes 248 * @q: the request queue for the device 249 * @max_write_zeroes_sectors: maximum number of sectors to write per command 250 **/ 251 void blk_queue_max_write_zeroes_sectors(struct request_queue *q, 252 unsigned int max_write_zeroes_sectors) 253 { 254 q->limits.max_write_zeroes_sectors = max_write_zeroes_sectors; 255 } 256 EXPORT_SYMBOL(blk_queue_max_write_zeroes_sectors); 257 258 /** 259 * blk_queue_max_segments - set max hw segments for a request for this queue 260 * @q: the request queue for the device 261 * @max_segments: max number of segments 262 * 263 * Description: 264 * Enables a low level driver to set an upper limit on the number of 265 * hw data segments in a request. 266 **/ 267 void blk_queue_max_segments(struct request_queue *q, unsigned short max_segments) 268 { 269 if (!max_segments) { 270 max_segments = 1; 271 printk(KERN_INFO "%s: set to minimum %d\n", 272 __func__, max_segments); 273 } 274 275 q->limits.max_segments = max_segments; 276 } 277 EXPORT_SYMBOL(blk_queue_max_segments); 278 279 /** 280 * blk_queue_max_discard_segments - set max segments for discard requests 281 * @q: the request queue for the device 282 * @max_segments: max number of segments 283 * 284 * Description: 285 * Enables a low level driver to set an upper limit on the number of 286 * segments in a discard request. 287 **/ 288 void blk_queue_max_discard_segments(struct request_queue *q, 289 unsigned short max_segments) 290 { 291 q->limits.max_discard_segments = max_segments; 292 } 293 EXPORT_SYMBOL_GPL(blk_queue_max_discard_segments); 294 295 /** 296 * blk_queue_max_segment_size - set max segment size for blk_rq_map_sg 297 * @q: the request queue for the device 298 * @max_size: max size of segment in bytes 299 * 300 * Description: 301 * Enables a low level driver to set an upper limit on the size of a 302 * coalesced segment 303 **/ 304 void blk_queue_max_segment_size(struct request_queue *q, unsigned int max_size) 305 { 306 if (max_size < PAGE_SIZE) { 307 max_size = PAGE_SIZE; 308 printk(KERN_INFO "%s: set to minimum %d\n", 309 __func__, max_size); 310 } 311 312 q->limits.max_segment_size = max_size; 313 } 314 EXPORT_SYMBOL(blk_queue_max_segment_size); 315 316 /** 317 * blk_queue_logical_block_size - set logical block size for the queue 318 * @q: the request queue for the device 319 * @size: the logical block size, in bytes 320 * 321 * Description: 322 * This should be set to the lowest possible block size that the 323 * storage device can address. The default of 512 covers most 324 * hardware. 325 **/ 326 void blk_queue_logical_block_size(struct request_queue *q, unsigned short size) 327 { 328 q->limits.logical_block_size = size; 329 330 if (q->limits.physical_block_size < size) 331 q->limits.physical_block_size = size; 332 333 if (q->limits.io_min < q->limits.physical_block_size) 334 q->limits.io_min = q->limits.physical_block_size; 335 } 336 EXPORT_SYMBOL(blk_queue_logical_block_size); 337 338 /** 339 * blk_queue_physical_block_size - set physical block size for the queue 340 * @q: the request queue for the device 341 * @size: the physical block size, in bytes 342 * 343 * Description: 344 * This should be set to the lowest possible sector size that the 345 * hardware can operate on without reverting to read-modify-write 346 * operations. 347 */ 348 void blk_queue_physical_block_size(struct request_queue *q, unsigned int size) 349 { 350 q->limits.physical_block_size = size; 351 352 if (q->limits.physical_block_size < q->limits.logical_block_size) 353 q->limits.physical_block_size = q->limits.logical_block_size; 354 355 if (q->limits.io_min < q->limits.physical_block_size) 356 q->limits.io_min = q->limits.physical_block_size; 357 } 358 EXPORT_SYMBOL(blk_queue_physical_block_size); 359 360 /** 361 * blk_queue_alignment_offset - set physical block alignment offset 362 * @q: the request queue for the device 363 * @offset: alignment offset in bytes 364 * 365 * Description: 366 * Some devices are naturally misaligned to compensate for things like 367 * the legacy DOS partition table 63-sector offset. Low-level drivers 368 * should call this function for devices whose first sector is not 369 * naturally aligned. 370 */ 371 void blk_queue_alignment_offset(struct request_queue *q, unsigned int offset) 372 { 373 q->limits.alignment_offset = 374 offset & (q->limits.physical_block_size - 1); 375 q->limits.misaligned = 0; 376 } 377 EXPORT_SYMBOL(blk_queue_alignment_offset); 378 379 /** 380 * blk_limits_io_min - set minimum request size for a device 381 * @limits: the queue limits 382 * @min: smallest I/O size in bytes 383 * 384 * Description: 385 * Some devices have an internal block size bigger than the reported 386 * hardware sector size. This function can be used to signal the 387 * smallest I/O the device can perform without incurring a performance 388 * penalty. 389 */ 390 void blk_limits_io_min(struct queue_limits *limits, unsigned int min) 391 { 392 limits->io_min = min; 393 394 if (limits->io_min < limits->logical_block_size) 395 limits->io_min = limits->logical_block_size; 396 397 if (limits->io_min < limits->physical_block_size) 398 limits->io_min = limits->physical_block_size; 399 } 400 EXPORT_SYMBOL(blk_limits_io_min); 401 402 /** 403 * blk_queue_io_min - set minimum request size for the queue 404 * @q: the request queue for the device 405 * @min: smallest I/O size in bytes 406 * 407 * Description: 408 * Storage devices may report a granularity or preferred minimum I/O 409 * size which is the smallest request the device can perform without 410 * incurring a performance penalty. For disk drives this is often the 411 * physical block size. For RAID arrays it is often the stripe chunk 412 * size. A properly aligned multiple of minimum_io_size is the 413 * preferred request size for workloads where a high number of I/O 414 * operations is desired. 415 */ 416 void blk_queue_io_min(struct request_queue *q, unsigned int min) 417 { 418 blk_limits_io_min(&q->limits, min); 419 } 420 EXPORT_SYMBOL(blk_queue_io_min); 421 422 /** 423 * blk_limits_io_opt - set optimal request size for a device 424 * @limits: the queue limits 425 * @opt: smallest I/O size in bytes 426 * 427 * Description: 428 * Storage devices may report an optimal I/O size, which is the 429 * device's preferred unit for sustained I/O. This is rarely reported 430 * for disk drives. For RAID arrays it is usually the stripe width or 431 * the internal track size. A properly aligned multiple of 432 * optimal_io_size is the preferred request size for workloads where 433 * sustained throughput is desired. 434 */ 435 void blk_limits_io_opt(struct queue_limits *limits, unsigned int opt) 436 { 437 limits->io_opt = opt; 438 } 439 EXPORT_SYMBOL(blk_limits_io_opt); 440 441 /** 442 * blk_queue_io_opt - set optimal request size for the queue 443 * @q: the request queue for the device 444 * @opt: optimal request size in bytes 445 * 446 * Description: 447 * Storage devices may report an optimal I/O size, which is the 448 * device's preferred unit for sustained I/O. This is rarely reported 449 * for disk drives. For RAID arrays it is usually the stripe width or 450 * the internal track size. A properly aligned multiple of 451 * optimal_io_size is the preferred request size for workloads where 452 * sustained throughput is desired. 453 */ 454 void blk_queue_io_opt(struct request_queue *q, unsigned int opt) 455 { 456 blk_limits_io_opt(&q->limits, opt); 457 } 458 EXPORT_SYMBOL(blk_queue_io_opt); 459 460 /** 461 * blk_queue_stack_limits - inherit underlying queue limits for stacked drivers 462 * @t: the stacking driver (top) 463 * @b: the underlying device (bottom) 464 **/ 465 void blk_queue_stack_limits(struct request_queue *t, struct request_queue *b) 466 { 467 blk_stack_limits(&t->limits, &b->limits, 0); 468 } 469 EXPORT_SYMBOL(blk_queue_stack_limits); 470 471 /** 472 * blk_stack_limits - adjust queue_limits for stacked devices 473 * @t: the stacking driver limits (top device) 474 * @b: the underlying queue limits (bottom, component device) 475 * @start: first data sector within component device 476 * 477 * Description: 478 * This function is used by stacking drivers like MD and DM to ensure 479 * that all component devices have compatible block sizes and 480 * alignments. The stacking driver must provide a queue_limits 481 * struct (top) and then iteratively call the stacking function for 482 * all component (bottom) devices. The stacking function will 483 * attempt to combine the values and ensure proper alignment. 484 * 485 * Returns 0 if the top and bottom queue_limits are compatible. The 486 * top device's block sizes and alignment offsets may be adjusted to 487 * ensure alignment with the bottom device. If no compatible sizes 488 * and alignments exist, -1 is returned and the resulting top 489 * queue_limits will have the misaligned flag set to indicate that 490 * the alignment_offset is undefined. 491 */ 492 int blk_stack_limits(struct queue_limits *t, struct queue_limits *b, 493 sector_t start) 494 { 495 unsigned int top, bottom, alignment, ret = 0; 496 497 t->max_sectors = min_not_zero(t->max_sectors, b->max_sectors); 498 t->max_hw_sectors = min_not_zero(t->max_hw_sectors, b->max_hw_sectors); 499 t->max_dev_sectors = min_not_zero(t->max_dev_sectors, b->max_dev_sectors); 500 t->max_write_same_sectors = min(t->max_write_same_sectors, 501 b->max_write_same_sectors); 502 t->max_write_zeroes_sectors = min(t->max_write_zeroes_sectors, 503 b->max_write_zeroes_sectors); 504 t->bounce_pfn = min_not_zero(t->bounce_pfn, b->bounce_pfn); 505 506 t->seg_boundary_mask = min_not_zero(t->seg_boundary_mask, 507 b->seg_boundary_mask); 508 t->virt_boundary_mask = min_not_zero(t->virt_boundary_mask, 509 b->virt_boundary_mask); 510 511 t->max_segments = min_not_zero(t->max_segments, b->max_segments); 512 t->max_discard_segments = min_not_zero(t->max_discard_segments, 513 b->max_discard_segments); 514 t->max_integrity_segments = min_not_zero(t->max_integrity_segments, 515 b->max_integrity_segments); 516 517 t->max_segment_size = min_not_zero(t->max_segment_size, 518 b->max_segment_size); 519 520 t->misaligned |= b->misaligned; 521 522 alignment = queue_limit_alignment_offset(b, start); 523 524 /* Bottom device has different alignment. Check that it is 525 * compatible with the current top alignment. 526 */ 527 if (t->alignment_offset != alignment) { 528 529 top = max(t->physical_block_size, t->io_min) 530 + t->alignment_offset; 531 bottom = max(b->physical_block_size, b->io_min) + alignment; 532 533 /* Verify that top and bottom intervals line up */ 534 if (max(top, bottom) % min(top, bottom)) { 535 t->misaligned = 1; 536 ret = -1; 537 } 538 } 539 540 t->logical_block_size = max(t->logical_block_size, 541 b->logical_block_size); 542 543 t->physical_block_size = max(t->physical_block_size, 544 b->physical_block_size); 545 546 t->io_min = max(t->io_min, b->io_min); 547 t->io_opt = lcm_not_zero(t->io_opt, b->io_opt); 548 549 /* Physical block size a multiple of the logical block size? */ 550 if (t->physical_block_size & (t->logical_block_size - 1)) { 551 t->physical_block_size = t->logical_block_size; 552 t->misaligned = 1; 553 ret = -1; 554 } 555 556 /* Minimum I/O a multiple of the physical block size? */ 557 if (t->io_min & (t->physical_block_size - 1)) { 558 t->io_min = t->physical_block_size; 559 t->misaligned = 1; 560 ret = -1; 561 } 562 563 /* Optimal I/O a multiple of the physical block size? */ 564 if (t->io_opt & (t->physical_block_size - 1)) { 565 t->io_opt = 0; 566 t->misaligned = 1; 567 ret = -1; 568 } 569 570 t->raid_partial_stripes_expensive = 571 max(t->raid_partial_stripes_expensive, 572 b->raid_partial_stripes_expensive); 573 574 /* Find lowest common alignment_offset */ 575 t->alignment_offset = lcm_not_zero(t->alignment_offset, alignment) 576 % max(t->physical_block_size, t->io_min); 577 578 /* Verify that new alignment_offset is on a logical block boundary */ 579 if (t->alignment_offset & (t->logical_block_size - 1)) { 580 t->misaligned = 1; 581 ret = -1; 582 } 583 584 /* Discard alignment and granularity */ 585 if (b->discard_granularity) { 586 alignment = queue_limit_discard_alignment(b, start); 587 588 if (t->discard_granularity != 0 && 589 t->discard_alignment != alignment) { 590 top = t->discard_granularity + t->discard_alignment; 591 bottom = b->discard_granularity + alignment; 592 593 /* Verify that top and bottom intervals line up */ 594 if ((max(top, bottom) % min(top, bottom)) != 0) 595 t->discard_misaligned = 1; 596 } 597 598 t->max_discard_sectors = min_not_zero(t->max_discard_sectors, 599 b->max_discard_sectors); 600 t->max_hw_discard_sectors = min_not_zero(t->max_hw_discard_sectors, 601 b->max_hw_discard_sectors); 602 t->discard_granularity = max(t->discard_granularity, 603 b->discard_granularity); 604 t->discard_alignment = lcm_not_zero(t->discard_alignment, alignment) % 605 t->discard_granularity; 606 } 607 608 if (b->chunk_sectors) 609 t->chunk_sectors = min_not_zero(t->chunk_sectors, 610 b->chunk_sectors); 611 612 return ret; 613 } 614 EXPORT_SYMBOL(blk_stack_limits); 615 616 /** 617 * bdev_stack_limits - adjust queue limits for stacked drivers 618 * @t: the stacking driver limits (top device) 619 * @bdev: the component block_device (bottom) 620 * @start: first data sector within component device 621 * 622 * Description: 623 * Merges queue limits for a top device and a block_device. Returns 624 * 0 if alignment didn't change. Returns -1 if adding the bottom 625 * device caused misalignment. 626 */ 627 int bdev_stack_limits(struct queue_limits *t, struct block_device *bdev, 628 sector_t start) 629 { 630 struct request_queue *bq = bdev_get_queue(bdev); 631 632 start += get_start_sect(bdev); 633 634 return blk_stack_limits(t, &bq->limits, start); 635 } 636 EXPORT_SYMBOL(bdev_stack_limits); 637 638 /** 639 * disk_stack_limits - adjust queue limits for stacked drivers 640 * @disk: MD/DM gendisk (top) 641 * @bdev: the underlying block device (bottom) 642 * @offset: offset to beginning of data within component device 643 * 644 * Description: 645 * Merges the limits for a top level gendisk and a bottom level 646 * block_device. 647 */ 648 void disk_stack_limits(struct gendisk *disk, struct block_device *bdev, 649 sector_t offset) 650 { 651 struct request_queue *t = disk->queue; 652 653 if (bdev_stack_limits(&t->limits, bdev, offset >> 9) < 0) { 654 char top[BDEVNAME_SIZE], bottom[BDEVNAME_SIZE]; 655 656 disk_name(disk, 0, top); 657 bdevname(bdev, bottom); 658 659 printk(KERN_NOTICE "%s: Warning: Device %s is misaligned\n", 660 top, bottom); 661 } 662 } 663 EXPORT_SYMBOL(disk_stack_limits); 664 665 /** 666 * blk_queue_dma_pad - set pad mask 667 * @q: the request queue for the device 668 * @mask: pad mask 669 * 670 * Set dma pad mask. 671 * 672 * Appending pad buffer to a request modifies the last entry of a 673 * scatter list such that it includes the pad buffer. 674 **/ 675 void blk_queue_dma_pad(struct request_queue *q, unsigned int mask) 676 { 677 q->dma_pad_mask = mask; 678 } 679 EXPORT_SYMBOL(blk_queue_dma_pad); 680 681 /** 682 * blk_queue_update_dma_pad - update pad mask 683 * @q: the request queue for the device 684 * @mask: pad mask 685 * 686 * Update dma pad mask. 687 * 688 * Appending pad buffer to a request modifies the last entry of a 689 * scatter list such that it includes the pad buffer. 690 **/ 691 void blk_queue_update_dma_pad(struct request_queue *q, unsigned int mask) 692 { 693 if (mask > q->dma_pad_mask) 694 q->dma_pad_mask = mask; 695 } 696 EXPORT_SYMBOL(blk_queue_update_dma_pad); 697 698 /** 699 * blk_queue_dma_drain - Set up a drain buffer for excess dma. 700 * @q: the request queue for the device 701 * @dma_drain_needed: fn which returns non-zero if drain is necessary 702 * @buf: physically contiguous buffer 703 * @size: size of the buffer in bytes 704 * 705 * Some devices have excess DMA problems and can't simply discard (or 706 * zero fill) the unwanted piece of the transfer. They have to have a 707 * real area of memory to transfer it into. The use case for this is 708 * ATAPI devices in DMA mode. If the packet command causes a transfer 709 * bigger than the transfer size some HBAs will lock up if there 710 * aren't DMA elements to contain the excess transfer. What this API 711 * does is adjust the queue so that the buf is always appended 712 * silently to the scatterlist. 713 * 714 * Note: This routine adjusts max_hw_segments to make room for appending 715 * the drain buffer. If you call blk_queue_max_segments() after calling 716 * this routine, you must set the limit to one fewer than your device 717 * can support otherwise there won't be room for the drain buffer. 718 */ 719 int blk_queue_dma_drain(struct request_queue *q, 720 dma_drain_needed_fn *dma_drain_needed, 721 void *buf, unsigned int size) 722 { 723 if (queue_max_segments(q) < 2) 724 return -EINVAL; 725 /* make room for appending the drain */ 726 blk_queue_max_segments(q, queue_max_segments(q) - 1); 727 q->dma_drain_needed = dma_drain_needed; 728 q->dma_drain_buffer = buf; 729 q->dma_drain_size = size; 730 731 return 0; 732 } 733 EXPORT_SYMBOL_GPL(blk_queue_dma_drain); 734 735 /** 736 * blk_queue_segment_boundary - set boundary rules for segment merging 737 * @q: the request queue for the device 738 * @mask: the memory boundary mask 739 **/ 740 void blk_queue_segment_boundary(struct request_queue *q, unsigned long mask) 741 { 742 if (mask < PAGE_SIZE - 1) { 743 mask = PAGE_SIZE - 1; 744 printk(KERN_INFO "%s: set to minimum %lx\n", 745 __func__, mask); 746 } 747 748 q->limits.seg_boundary_mask = mask; 749 } 750 EXPORT_SYMBOL(blk_queue_segment_boundary); 751 752 /** 753 * blk_queue_virt_boundary - set boundary rules for bio merging 754 * @q: the request queue for the device 755 * @mask: the memory boundary mask 756 **/ 757 void blk_queue_virt_boundary(struct request_queue *q, unsigned long mask) 758 { 759 q->limits.virt_boundary_mask = mask; 760 } 761 EXPORT_SYMBOL(blk_queue_virt_boundary); 762 763 /** 764 * blk_queue_dma_alignment - set dma length and memory alignment 765 * @q: the request queue for the device 766 * @mask: alignment mask 767 * 768 * description: 769 * set required memory and length alignment for direct dma transactions. 770 * this is used when building direct io requests for the queue. 771 * 772 **/ 773 void blk_queue_dma_alignment(struct request_queue *q, int mask) 774 { 775 q->dma_alignment = mask; 776 } 777 EXPORT_SYMBOL(blk_queue_dma_alignment); 778 779 /** 780 * blk_queue_update_dma_alignment - update dma length and memory alignment 781 * @q: the request queue for the device 782 * @mask: alignment mask 783 * 784 * description: 785 * update required memory and length alignment for direct dma transactions. 786 * If the requested alignment is larger than the current alignment, then 787 * the current queue alignment is updated to the new value, otherwise it 788 * is left alone. The design of this is to allow multiple objects 789 * (driver, device, transport etc) to set their respective 790 * alignments without having them interfere. 791 * 792 **/ 793 void blk_queue_update_dma_alignment(struct request_queue *q, int mask) 794 { 795 BUG_ON(mask > PAGE_SIZE); 796 797 if (mask > q->dma_alignment) 798 q->dma_alignment = mask; 799 } 800 EXPORT_SYMBOL(blk_queue_update_dma_alignment); 801 802 /** 803 * blk_set_queue_depth - tell the block layer about the device queue depth 804 * @q: the request queue for the device 805 * @depth: queue depth 806 * 807 */ 808 void blk_set_queue_depth(struct request_queue *q, unsigned int depth) 809 { 810 q->queue_depth = depth; 811 wbt_set_queue_depth(q, depth); 812 } 813 EXPORT_SYMBOL(blk_set_queue_depth); 814 815 /** 816 * blk_queue_write_cache - configure queue's write cache 817 * @q: the request queue for the device 818 * @wc: write back cache on or off 819 * @fua: device supports FUA writes, if true 820 * 821 * Tell the block layer about the write cache of @q. 822 */ 823 void blk_queue_write_cache(struct request_queue *q, bool wc, bool fua) 824 { 825 if (wc) 826 blk_queue_flag_set(QUEUE_FLAG_WC, q); 827 else 828 blk_queue_flag_clear(QUEUE_FLAG_WC, q); 829 if (fua) 830 blk_queue_flag_set(QUEUE_FLAG_FUA, q); 831 else 832 blk_queue_flag_clear(QUEUE_FLAG_FUA, q); 833 834 wbt_set_write_cache(q, test_bit(QUEUE_FLAG_WC, &q->queue_flags)); 835 } 836 EXPORT_SYMBOL_GPL(blk_queue_write_cache); 837 838 static int __init blk_settings_init(void) 839 { 840 blk_max_low_pfn = max_low_pfn - 1; 841 blk_max_pfn = max_pfn - 1; 842 return 0; 843 } 844 subsys_initcall(blk_settings_init); 845