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/bootmem.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 17 unsigned long blk_max_low_pfn; 18 EXPORT_SYMBOL(blk_max_low_pfn); 19 20 unsigned long blk_max_pfn; 21 22 /** 23 * blk_queue_prep_rq - set a prepare_request function for queue 24 * @q: queue 25 * @pfn: prepare_request function 26 * 27 * It's possible for a queue to register a prepare_request callback which 28 * is invoked before the request is handed to the request_fn. The goal of 29 * the function is to prepare a request for I/O, it can be used to build a 30 * cdb from the request data for instance. 31 * 32 */ 33 void blk_queue_prep_rq(struct request_queue *q, prep_rq_fn *pfn) 34 { 35 q->prep_rq_fn = pfn; 36 } 37 EXPORT_SYMBOL(blk_queue_prep_rq); 38 39 /** 40 * blk_queue_unprep_rq - set an unprepare_request function for queue 41 * @q: queue 42 * @ufn: unprepare_request function 43 * 44 * It's possible for a queue to register an unprepare_request callback 45 * which is invoked before the request is finally completed. The goal 46 * of the function is to deallocate any data that was allocated in the 47 * prepare_request callback. 48 * 49 */ 50 void blk_queue_unprep_rq(struct request_queue *q, unprep_rq_fn *ufn) 51 { 52 q->unprep_rq_fn = ufn; 53 } 54 EXPORT_SYMBOL(blk_queue_unprep_rq); 55 56 /** 57 * blk_queue_merge_bvec - set a merge_bvec function for queue 58 * @q: queue 59 * @mbfn: merge_bvec_fn 60 * 61 * Usually queues have static limitations on the max sectors or segments that 62 * we can put in a request. Stacking drivers may have some settings that 63 * are dynamic, and thus we have to query the queue whether it is ok to 64 * add a new bio_vec to a bio at a given offset or not. If the block device 65 * has such limitations, it needs to register a merge_bvec_fn to control 66 * the size of bio's sent to it. Note that a block device *must* allow a 67 * single page to be added to an empty bio. The block device driver may want 68 * to use the bio_split() function to deal with these bio's. By default 69 * no merge_bvec_fn is defined for a queue, and only the fixed limits are 70 * honored. 71 */ 72 void blk_queue_merge_bvec(struct request_queue *q, merge_bvec_fn *mbfn) 73 { 74 q->merge_bvec_fn = mbfn; 75 } 76 EXPORT_SYMBOL(blk_queue_merge_bvec); 77 78 void blk_queue_softirq_done(struct request_queue *q, softirq_done_fn *fn) 79 { 80 q->softirq_done_fn = fn; 81 } 82 EXPORT_SYMBOL(blk_queue_softirq_done); 83 84 void blk_queue_rq_timeout(struct request_queue *q, unsigned int timeout) 85 { 86 q->rq_timeout = timeout; 87 } 88 EXPORT_SYMBOL_GPL(blk_queue_rq_timeout); 89 90 void blk_queue_rq_timed_out(struct request_queue *q, rq_timed_out_fn *fn) 91 { 92 q->rq_timed_out_fn = fn; 93 } 94 EXPORT_SYMBOL_GPL(blk_queue_rq_timed_out); 95 96 void blk_queue_lld_busy(struct request_queue *q, lld_busy_fn *fn) 97 { 98 q->lld_busy_fn = fn; 99 } 100 EXPORT_SYMBOL_GPL(blk_queue_lld_busy); 101 102 /** 103 * blk_set_default_limits - reset limits to default values 104 * @lim: the queue_limits structure to reset 105 * 106 * Description: 107 * Returns a queue_limit struct to its default state. 108 */ 109 void blk_set_default_limits(struct queue_limits *lim) 110 { 111 lim->max_segments = BLK_MAX_SEGMENTS; 112 lim->max_integrity_segments = 0; 113 lim->seg_boundary_mask = BLK_SEG_BOUNDARY_MASK; 114 lim->max_segment_size = BLK_MAX_SEGMENT_SIZE; 115 lim->max_sectors = lim->max_hw_sectors = BLK_SAFE_MAX_SECTORS; 116 lim->chunk_sectors = 0; 117 lim->max_write_same_sectors = 0; 118 lim->max_discard_sectors = 0; 119 lim->discard_granularity = 0; 120 lim->discard_alignment = 0; 121 lim->discard_misaligned = 0; 122 lim->discard_zeroes_data = 0; 123 lim->logical_block_size = lim->physical_block_size = lim->io_min = 512; 124 lim->bounce_pfn = (unsigned long)(BLK_BOUNCE_ANY >> PAGE_SHIFT); 125 lim->alignment_offset = 0; 126 lim->io_opt = 0; 127 lim->misaligned = 0; 128 lim->cluster = 1; 129 } 130 EXPORT_SYMBOL(blk_set_default_limits); 131 132 /** 133 * blk_set_stacking_limits - set default limits for stacking devices 134 * @lim: the queue_limits structure to reset 135 * 136 * Description: 137 * Returns a queue_limit struct to its default state. Should be used 138 * by stacking drivers like DM that have no internal limits. 139 */ 140 void blk_set_stacking_limits(struct queue_limits *lim) 141 { 142 blk_set_default_limits(lim); 143 144 /* Inherit limits from component devices */ 145 lim->discard_zeroes_data = 1; 146 lim->max_segments = USHRT_MAX; 147 lim->max_hw_sectors = UINT_MAX; 148 lim->max_segment_size = UINT_MAX; 149 lim->max_sectors = UINT_MAX; 150 lim->max_write_same_sectors = UINT_MAX; 151 } 152 EXPORT_SYMBOL(blk_set_stacking_limits); 153 154 /** 155 * blk_queue_make_request - define an alternate make_request function for a device 156 * @q: the request queue for the device to be affected 157 * @mfn: the alternate make_request function 158 * 159 * Description: 160 * The normal way for &struct bios to be passed to a device 161 * driver is for them to be collected into requests on a request 162 * queue, and then to allow the device driver to select requests 163 * off that queue when it is ready. This works well for many block 164 * devices. However some block devices (typically virtual devices 165 * such as md or lvm) do not benefit from the processing on the 166 * request queue, and are served best by having the requests passed 167 * directly to them. This can be achieved by providing a function 168 * to blk_queue_make_request(). 169 * 170 * Caveat: 171 * The driver that does this *must* be able to deal appropriately 172 * with buffers in "highmemory". This can be accomplished by either calling 173 * __bio_kmap_atomic() to get a temporary kernel mapping, or by calling 174 * blk_queue_bounce() to create a buffer in normal memory. 175 **/ 176 void blk_queue_make_request(struct request_queue *q, make_request_fn *mfn) 177 { 178 /* 179 * set defaults 180 */ 181 q->nr_requests = BLKDEV_MAX_RQ; 182 183 q->make_request_fn = mfn; 184 blk_queue_dma_alignment(q, 511); 185 blk_queue_congestion_threshold(q); 186 q->nr_batching = BLK_BATCH_REQ; 187 188 blk_set_default_limits(&q->limits); 189 190 /* 191 * by default assume old behaviour and bounce for any highmem page 192 */ 193 blk_queue_bounce_limit(q, BLK_BOUNCE_HIGH); 194 } 195 EXPORT_SYMBOL(blk_queue_make_request); 196 197 /** 198 * blk_queue_bounce_limit - set bounce buffer limit for queue 199 * @q: the request queue for the device 200 * @max_addr: the maximum address the device can handle 201 * 202 * Description: 203 * Different hardware can have different requirements as to what pages 204 * it can do I/O directly to. A low level driver can call 205 * blk_queue_bounce_limit to have lower memory pages allocated as bounce 206 * buffers for doing I/O to pages residing above @max_addr. 207 **/ 208 void blk_queue_bounce_limit(struct request_queue *q, u64 max_addr) 209 { 210 unsigned long b_pfn = max_addr >> PAGE_SHIFT; 211 int dma = 0; 212 213 q->bounce_gfp = GFP_NOIO; 214 #if BITS_PER_LONG == 64 215 /* 216 * Assume anything <= 4GB can be handled by IOMMU. Actually 217 * some IOMMUs can handle everything, but I don't know of a 218 * way to test this here. 219 */ 220 if (b_pfn < (min_t(u64, 0xffffffffUL, BLK_BOUNCE_HIGH) >> PAGE_SHIFT)) 221 dma = 1; 222 q->limits.bounce_pfn = max(max_low_pfn, b_pfn); 223 #else 224 if (b_pfn < blk_max_low_pfn) 225 dma = 1; 226 q->limits.bounce_pfn = b_pfn; 227 #endif 228 if (dma) { 229 init_emergency_isa_pool(); 230 q->bounce_gfp = GFP_NOIO | GFP_DMA; 231 q->limits.bounce_pfn = b_pfn; 232 } 233 } 234 EXPORT_SYMBOL(blk_queue_bounce_limit); 235 236 /** 237 * blk_limits_max_hw_sectors - set hard and soft limit of max sectors for request 238 * @limits: the queue limits 239 * @max_hw_sectors: max hardware sectors in the usual 512b unit 240 * 241 * Description: 242 * Enables a low level driver to set a hard upper limit, 243 * max_hw_sectors, on the size of requests. max_hw_sectors is set by 244 * the device driver based upon the combined capabilities of I/O 245 * controller and storage device. 246 * 247 * max_sectors is a soft limit imposed by the block layer for 248 * filesystem type requests. This value can be overridden on a 249 * per-device basis in /sys/block/<device>/queue/max_sectors_kb. 250 * The soft limit can not exceed max_hw_sectors. 251 **/ 252 void blk_limits_max_hw_sectors(struct queue_limits *limits, unsigned int max_hw_sectors) 253 { 254 if ((max_hw_sectors << 9) < PAGE_CACHE_SIZE) { 255 max_hw_sectors = 1 << (PAGE_CACHE_SHIFT - 9); 256 printk(KERN_INFO "%s: set to minimum %d\n", 257 __func__, max_hw_sectors); 258 } 259 260 limits->max_hw_sectors = max_hw_sectors; 261 limits->max_sectors = min_t(unsigned int, max_hw_sectors, 262 BLK_DEF_MAX_SECTORS); 263 } 264 EXPORT_SYMBOL(blk_limits_max_hw_sectors); 265 266 /** 267 * blk_queue_max_hw_sectors - set max sectors for a request for this queue 268 * @q: the request queue for the device 269 * @max_hw_sectors: max hardware sectors in the usual 512b unit 270 * 271 * Description: 272 * See description for blk_limits_max_hw_sectors(). 273 **/ 274 void blk_queue_max_hw_sectors(struct request_queue *q, unsigned int max_hw_sectors) 275 { 276 blk_limits_max_hw_sectors(&q->limits, max_hw_sectors); 277 } 278 EXPORT_SYMBOL(blk_queue_max_hw_sectors); 279 280 /** 281 * blk_queue_chunk_sectors - set size of the chunk for this queue 282 * @q: the request queue for the device 283 * @chunk_sectors: chunk sectors in the usual 512b unit 284 * 285 * Description: 286 * If a driver doesn't want IOs to cross a given chunk size, it can set 287 * this limit and prevent merging across chunks. Note that the chunk size 288 * must currently be a power-of-2 in sectors. Also note that the block 289 * layer must accept a page worth of data at any offset. So if the 290 * crossing of chunks is a hard limitation in the driver, it must still be 291 * prepared to split single page bios. 292 **/ 293 void blk_queue_chunk_sectors(struct request_queue *q, unsigned int chunk_sectors) 294 { 295 BUG_ON(!is_power_of_2(chunk_sectors)); 296 q->limits.chunk_sectors = chunk_sectors; 297 } 298 EXPORT_SYMBOL(blk_queue_chunk_sectors); 299 300 /** 301 * blk_queue_max_discard_sectors - set max sectors for a single discard 302 * @q: the request queue for the device 303 * @max_discard_sectors: maximum number of sectors to discard 304 **/ 305 void blk_queue_max_discard_sectors(struct request_queue *q, 306 unsigned int max_discard_sectors) 307 { 308 q->limits.max_discard_sectors = max_discard_sectors; 309 } 310 EXPORT_SYMBOL(blk_queue_max_discard_sectors); 311 312 /** 313 * blk_queue_max_write_same_sectors - set max sectors for a single write same 314 * @q: the request queue for the device 315 * @max_write_same_sectors: maximum number of sectors to write per command 316 **/ 317 void blk_queue_max_write_same_sectors(struct request_queue *q, 318 unsigned int max_write_same_sectors) 319 { 320 q->limits.max_write_same_sectors = max_write_same_sectors; 321 } 322 EXPORT_SYMBOL(blk_queue_max_write_same_sectors); 323 324 /** 325 * blk_queue_max_segments - set max hw segments for a request for this queue 326 * @q: the request queue for the device 327 * @max_segments: max number of segments 328 * 329 * Description: 330 * Enables a low level driver to set an upper limit on the number of 331 * hw data segments in a request. 332 **/ 333 void blk_queue_max_segments(struct request_queue *q, unsigned short max_segments) 334 { 335 if (!max_segments) { 336 max_segments = 1; 337 printk(KERN_INFO "%s: set to minimum %d\n", 338 __func__, max_segments); 339 } 340 341 q->limits.max_segments = max_segments; 342 } 343 EXPORT_SYMBOL(blk_queue_max_segments); 344 345 /** 346 * blk_queue_max_segment_size - set max segment size for blk_rq_map_sg 347 * @q: the request queue for the device 348 * @max_size: max size of segment in bytes 349 * 350 * Description: 351 * Enables a low level driver to set an upper limit on the size of a 352 * coalesced segment 353 **/ 354 void blk_queue_max_segment_size(struct request_queue *q, unsigned int max_size) 355 { 356 if (max_size < PAGE_CACHE_SIZE) { 357 max_size = PAGE_CACHE_SIZE; 358 printk(KERN_INFO "%s: set to minimum %d\n", 359 __func__, max_size); 360 } 361 362 q->limits.max_segment_size = max_size; 363 } 364 EXPORT_SYMBOL(blk_queue_max_segment_size); 365 366 /** 367 * blk_queue_logical_block_size - set logical block size for the queue 368 * @q: the request queue for the device 369 * @size: the logical block size, in bytes 370 * 371 * Description: 372 * This should be set to the lowest possible block size that the 373 * storage device can address. The default of 512 covers most 374 * hardware. 375 **/ 376 void blk_queue_logical_block_size(struct request_queue *q, unsigned short size) 377 { 378 q->limits.logical_block_size = size; 379 380 if (q->limits.physical_block_size < size) 381 q->limits.physical_block_size = size; 382 383 if (q->limits.io_min < q->limits.physical_block_size) 384 q->limits.io_min = q->limits.physical_block_size; 385 } 386 EXPORT_SYMBOL(blk_queue_logical_block_size); 387 388 /** 389 * blk_queue_physical_block_size - set physical block size for the queue 390 * @q: the request queue for the device 391 * @size: the physical block size, in bytes 392 * 393 * Description: 394 * This should be set to the lowest possible sector size that the 395 * hardware can operate on without reverting to read-modify-write 396 * operations. 397 */ 398 void blk_queue_physical_block_size(struct request_queue *q, unsigned int size) 399 { 400 q->limits.physical_block_size = size; 401 402 if (q->limits.physical_block_size < q->limits.logical_block_size) 403 q->limits.physical_block_size = q->limits.logical_block_size; 404 405 if (q->limits.io_min < q->limits.physical_block_size) 406 q->limits.io_min = q->limits.physical_block_size; 407 } 408 EXPORT_SYMBOL(blk_queue_physical_block_size); 409 410 /** 411 * blk_queue_alignment_offset - set physical block alignment offset 412 * @q: the request queue for the device 413 * @offset: alignment offset in bytes 414 * 415 * Description: 416 * Some devices are naturally misaligned to compensate for things like 417 * the legacy DOS partition table 63-sector offset. Low-level drivers 418 * should call this function for devices whose first sector is not 419 * naturally aligned. 420 */ 421 void blk_queue_alignment_offset(struct request_queue *q, unsigned int offset) 422 { 423 q->limits.alignment_offset = 424 offset & (q->limits.physical_block_size - 1); 425 q->limits.misaligned = 0; 426 } 427 EXPORT_SYMBOL(blk_queue_alignment_offset); 428 429 /** 430 * blk_limits_io_min - set minimum request size for a device 431 * @limits: the queue limits 432 * @min: smallest I/O size in bytes 433 * 434 * Description: 435 * Some devices have an internal block size bigger than the reported 436 * hardware sector size. This function can be used to signal the 437 * smallest I/O the device can perform without incurring a performance 438 * penalty. 439 */ 440 void blk_limits_io_min(struct queue_limits *limits, unsigned int min) 441 { 442 limits->io_min = min; 443 444 if (limits->io_min < limits->logical_block_size) 445 limits->io_min = limits->logical_block_size; 446 447 if (limits->io_min < limits->physical_block_size) 448 limits->io_min = limits->physical_block_size; 449 } 450 EXPORT_SYMBOL(blk_limits_io_min); 451 452 /** 453 * blk_queue_io_min - set minimum request size for the queue 454 * @q: the request queue for the device 455 * @min: smallest I/O size in bytes 456 * 457 * Description: 458 * Storage devices may report a granularity or preferred minimum I/O 459 * size which is the smallest request the device can perform without 460 * incurring a performance penalty. For disk drives this is often the 461 * physical block size. For RAID arrays it is often the stripe chunk 462 * size. A properly aligned multiple of minimum_io_size is the 463 * preferred request size for workloads where a high number of I/O 464 * operations is desired. 465 */ 466 void blk_queue_io_min(struct request_queue *q, unsigned int min) 467 { 468 blk_limits_io_min(&q->limits, min); 469 } 470 EXPORT_SYMBOL(blk_queue_io_min); 471 472 /** 473 * blk_limits_io_opt - set optimal request size for a device 474 * @limits: the queue limits 475 * @opt: smallest I/O size in bytes 476 * 477 * Description: 478 * Storage devices may report an optimal I/O size, which is the 479 * device's preferred unit for sustained I/O. This is rarely reported 480 * for disk drives. For RAID arrays it is usually the stripe width or 481 * the internal track size. A properly aligned multiple of 482 * optimal_io_size is the preferred request size for workloads where 483 * sustained throughput is desired. 484 */ 485 void blk_limits_io_opt(struct queue_limits *limits, unsigned int opt) 486 { 487 limits->io_opt = opt; 488 } 489 EXPORT_SYMBOL(blk_limits_io_opt); 490 491 /** 492 * blk_queue_io_opt - set optimal request size for the queue 493 * @q: the request queue for the device 494 * @opt: optimal request size in bytes 495 * 496 * Description: 497 * Storage devices may report an optimal I/O size, which is the 498 * device's preferred unit for sustained I/O. This is rarely reported 499 * for disk drives. For RAID arrays it is usually the stripe width or 500 * the internal track size. A properly aligned multiple of 501 * optimal_io_size is the preferred request size for workloads where 502 * sustained throughput is desired. 503 */ 504 void blk_queue_io_opt(struct request_queue *q, unsigned int opt) 505 { 506 blk_limits_io_opt(&q->limits, opt); 507 } 508 EXPORT_SYMBOL(blk_queue_io_opt); 509 510 /** 511 * blk_queue_stack_limits - inherit underlying queue limits for stacked drivers 512 * @t: the stacking driver (top) 513 * @b: the underlying device (bottom) 514 **/ 515 void blk_queue_stack_limits(struct request_queue *t, struct request_queue *b) 516 { 517 blk_stack_limits(&t->limits, &b->limits, 0); 518 } 519 EXPORT_SYMBOL(blk_queue_stack_limits); 520 521 /** 522 * blk_stack_limits - adjust queue_limits for stacked devices 523 * @t: the stacking driver limits (top device) 524 * @b: the underlying queue limits (bottom, component device) 525 * @start: first data sector within component device 526 * 527 * Description: 528 * This function is used by stacking drivers like MD and DM to ensure 529 * that all component devices have compatible block sizes and 530 * alignments. The stacking driver must provide a queue_limits 531 * struct (top) and then iteratively call the stacking function for 532 * all component (bottom) devices. The stacking function will 533 * attempt to combine the values and ensure proper alignment. 534 * 535 * Returns 0 if the top and bottom queue_limits are compatible. The 536 * top device's block sizes and alignment offsets may be adjusted to 537 * ensure alignment with the bottom device. If no compatible sizes 538 * and alignments exist, -1 is returned and the resulting top 539 * queue_limits will have the misaligned flag set to indicate that 540 * the alignment_offset is undefined. 541 */ 542 int blk_stack_limits(struct queue_limits *t, struct queue_limits *b, 543 sector_t start) 544 { 545 unsigned int top, bottom, alignment, ret = 0; 546 547 t->max_sectors = min_not_zero(t->max_sectors, b->max_sectors); 548 t->max_hw_sectors = min_not_zero(t->max_hw_sectors, b->max_hw_sectors); 549 t->max_write_same_sectors = min(t->max_write_same_sectors, 550 b->max_write_same_sectors); 551 t->bounce_pfn = min_not_zero(t->bounce_pfn, b->bounce_pfn); 552 553 t->seg_boundary_mask = min_not_zero(t->seg_boundary_mask, 554 b->seg_boundary_mask); 555 556 t->max_segments = min_not_zero(t->max_segments, b->max_segments); 557 t->max_integrity_segments = min_not_zero(t->max_integrity_segments, 558 b->max_integrity_segments); 559 560 t->max_segment_size = min_not_zero(t->max_segment_size, 561 b->max_segment_size); 562 563 t->misaligned |= b->misaligned; 564 565 alignment = queue_limit_alignment_offset(b, start); 566 567 /* Bottom device has different alignment. Check that it is 568 * compatible with the current top alignment. 569 */ 570 if (t->alignment_offset != alignment) { 571 572 top = max(t->physical_block_size, t->io_min) 573 + t->alignment_offset; 574 bottom = max(b->physical_block_size, b->io_min) + alignment; 575 576 /* Verify that top and bottom intervals line up */ 577 if (max(top, bottom) & (min(top, bottom) - 1)) { 578 t->misaligned = 1; 579 ret = -1; 580 } 581 } 582 583 t->logical_block_size = max(t->logical_block_size, 584 b->logical_block_size); 585 586 t->physical_block_size = max(t->physical_block_size, 587 b->physical_block_size); 588 589 t->io_min = max(t->io_min, b->io_min); 590 t->io_opt = lcm(t->io_opt, b->io_opt); 591 592 t->cluster &= b->cluster; 593 t->discard_zeroes_data &= b->discard_zeroes_data; 594 595 /* Physical block size a multiple of the logical block size? */ 596 if (t->physical_block_size & (t->logical_block_size - 1)) { 597 t->physical_block_size = t->logical_block_size; 598 t->misaligned = 1; 599 ret = -1; 600 } 601 602 /* Minimum I/O a multiple of the physical block size? */ 603 if (t->io_min & (t->physical_block_size - 1)) { 604 t->io_min = t->physical_block_size; 605 t->misaligned = 1; 606 ret = -1; 607 } 608 609 /* Optimal I/O a multiple of the physical block size? */ 610 if (t->io_opt & (t->physical_block_size - 1)) { 611 t->io_opt = 0; 612 t->misaligned = 1; 613 ret = -1; 614 } 615 616 t->raid_partial_stripes_expensive = 617 max(t->raid_partial_stripes_expensive, 618 b->raid_partial_stripes_expensive); 619 620 /* Find lowest common alignment_offset */ 621 t->alignment_offset = lcm(t->alignment_offset, alignment) 622 & (max(t->physical_block_size, t->io_min) - 1); 623 624 /* Verify that new alignment_offset is on a logical block boundary */ 625 if (t->alignment_offset & (t->logical_block_size - 1)) { 626 t->misaligned = 1; 627 ret = -1; 628 } 629 630 /* Discard alignment and granularity */ 631 if (b->discard_granularity) { 632 alignment = queue_limit_discard_alignment(b, start); 633 634 if (t->discard_granularity != 0 && 635 t->discard_alignment != alignment) { 636 top = t->discard_granularity + t->discard_alignment; 637 bottom = b->discard_granularity + alignment; 638 639 /* Verify that top and bottom intervals line up */ 640 if ((max(top, bottom) % min(top, bottom)) != 0) 641 t->discard_misaligned = 1; 642 } 643 644 t->max_discard_sectors = min_not_zero(t->max_discard_sectors, 645 b->max_discard_sectors); 646 t->discard_granularity = max(t->discard_granularity, 647 b->discard_granularity); 648 t->discard_alignment = lcm(t->discard_alignment, alignment) % 649 t->discard_granularity; 650 } 651 652 return ret; 653 } 654 EXPORT_SYMBOL(blk_stack_limits); 655 656 /** 657 * bdev_stack_limits - adjust queue limits for stacked drivers 658 * @t: the stacking driver limits (top device) 659 * @bdev: the component block_device (bottom) 660 * @start: first data sector within component device 661 * 662 * Description: 663 * Merges queue limits for a top device and a block_device. Returns 664 * 0 if alignment didn't change. Returns -1 if adding the bottom 665 * device caused misalignment. 666 */ 667 int bdev_stack_limits(struct queue_limits *t, struct block_device *bdev, 668 sector_t start) 669 { 670 struct request_queue *bq = bdev_get_queue(bdev); 671 672 start += get_start_sect(bdev); 673 674 return blk_stack_limits(t, &bq->limits, start); 675 } 676 EXPORT_SYMBOL(bdev_stack_limits); 677 678 /** 679 * disk_stack_limits - adjust queue limits for stacked drivers 680 * @disk: MD/DM gendisk (top) 681 * @bdev: the underlying block device (bottom) 682 * @offset: offset to beginning of data within component device 683 * 684 * Description: 685 * Merges the limits for a top level gendisk and a bottom level 686 * block_device. 687 */ 688 void disk_stack_limits(struct gendisk *disk, struct block_device *bdev, 689 sector_t offset) 690 { 691 struct request_queue *t = disk->queue; 692 693 if (bdev_stack_limits(&t->limits, bdev, offset >> 9) < 0) { 694 char top[BDEVNAME_SIZE], bottom[BDEVNAME_SIZE]; 695 696 disk_name(disk, 0, top); 697 bdevname(bdev, bottom); 698 699 printk(KERN_NOTICE "%s: Warning: Device %s is misaligned\n", 700 top, bottom); 701 } 702 } 703 EXPORT_SYMBOL(disk_stack_limits); 704 705 /** 706 * blk_queue_dma_pad - set pad mask 707 * @q: the request queue for the device 708 * @mask: pad mask 709 * 710 * Set dma pad mask. 711 * 712 * Appending pad buffer to a request modifies the last entry of a 713 * scatter list such that it includes the pad buffer. 714 **/ 715 void blk_queue_dma_pad(struct request_queue *q, unsigned int mask) 716 { 717 q->dma_pad_mask = mask; 718 } 719 EXPORT_SYMBOL(blk_queue_dma_pad); 720 721 /** 722 * blk_queue_update_dma_pad - update pad mask 723 * @q: the request queue for the device 724 * @mask: pad mask 725 * 726 * Update dma pad mask. 727 * 728 * Appending pad buffer to a request modifies the last entry of a 729 * scatter list such that it includes the pad buffer. 730 **/ 731 void blk_queue_update_dma_pad(struct request_queue *q, unsigned int mask) 732 { 733 if (mask > q->dma_pad_mask) 734 q->dma_pad_mask = mask; 735 } 736 EXPORT_SYMBOL(blk_queue_update_dma_pad); 737 738 /** 739 * blk_queue_dma_drain - Set up a drain buffer for excess dma. 740 * @q: the request queue for the device 741 * @dma_drain_needed: fn which returns non-zero if drain is necessary 742 * @buf: physically contiguous buffer 743 * @size: size of the buffer in bytes 744 * 745 * Some devices have excess DMA problems and can't simply discard (or 746 * zero fill) the unwanted piece of the transfer. They have to have a 747 * real area of memory to transfer it into. The use case for this is 748 * ATAPI devices in DMA mode. If the packet command causes a transfer 749 * bigger than the transfer size some HBAs will lock up if there 750 * aren't DMA elements to contain the excess transfer. What this API 751 * does is adjust the queue so that the buf is always appended 752 * silently to the scatterlist. 753 * 754 * Note: This routine adjusts max_hw_segments to make room for appending 755 * the drain buffer. If you call blk_queue_max_segments() after calling 756 * this routine, you must set the limit to one fewer than your device 757 * can support otherwise there won't be room for the drain buffer. 758 */ 759 int blk_queue_dma_drain(struct request_queue *q, 760 dma_drain_needed_fn *dma_drain_needed, 761 void *buf, unsigned int size) 762 { 763 if (queue_max_segments(q) < 2) 764 return -EINVAL; 765 /* make room for appending the drain */ 766 blk_queue_max_segments(q, queue_max_segments(q) - 1); 767 q->dma_drain_needed = dma_drain_needed; 768 q->dma_drain_buffer = buf; 769 q->dma_drain_size = size; 770 771 return 0; 772 } 773 EXPORT_SYMBOL_GPL(blk_queue_dma_drain); 774 775 /** 776 * blk_queue_segment_boundary - set boundary rules for segment merging 777 * @q: the request queue for the device 778 * @mask: the memory boundary mask 779 **/ 780 void blk_queue_segment_boundary(struct request_queue *q, unsigned long mask) 781 { 782 if (mask < PAGE_CACHE_SIZE - 1) { 783 mask = PAGE_CACHE_SIZE - 1; 784 printk(KERN_INFO "%s: set to minimum %lx\n", 785 __func__, mask); 786 } 787 788 q->limits.seg_boundary_mask = mask; 789 } 790 EXPORT_SYMBOL(blk_queue_segment_boundary); 791 792 /** 793 * blk_queue_dma_alignment - set dma length and memory alignment 794 * @q: the request queue for the device 795 * @mask: alignment mask 796 * 797 * description: 798 * set required memory and length alignment for direct dma transactions. 799 * this is used when building direct io requests for the queue. 800 * 801 **/ 802 void blk_queue_dma_alignment(struct request_queue *q, int mask) 803 { 804 q->dma_alignment = mask; 805 } 806 EXPORT_SYMBOL(blk_queue_dma_alignment); 807 808 /** 809 * blk_queue_update_dma_alignment - update dma length and memory alignment 810 * @q: the request queue for the device 811 * @mask: alignment mask 812 * 813 * description: 814 * update required memory and length alignment for direct dma transactions. 815 * If the requested alignment is larger than the current alignment, then 816 * the current queue alignment is updated to the new value, otherwise it 817 * is left alone. The design of this is to allow multiple objects 818 * (driver, device, transport etc) to set their respective 819 * alignments without having them interfere. 820 * 821 **/ 822 void blk_queue_update_dma_alignment(struct request_queue *q, int mask) 823 { 824 BUG_ON(mask > PAGE_SIZE); 825 826 if (mask > q->dma_alignment) 827 q->dma_alignment = mask; 828 } 829 EXPORT_SYMBOL(blk_queue_update_dma_alignment); 830 831 /** 832 * blk_queue_flush - configure queue's cache flush capability 833 * @q: the request queue for the device 834 * @flush: 0, REQ_FLUSH or REQ_FLUSH | REQ_FUA 835 * 836 * Tell block layer cache flush capability of @q. If it supports 837 * flushing, REQ_FLUSH should be set. If it supports bypassing 838 * write cache for individual writes, REQ_FUA should be set. 839 */ 840 void blk_queue_flush(struct request_queue *q, unsigned int flush) 841 { 842 WARN_ON_ONCE(flush & ~(REQ_FLUSH | REQ_FUA)); 843 844 if (WARN_ON_ONCE(!(flush & REQ_FLUSH) && (flush & REQ_FUA))) 845 flush &= ~REQ_FUA; 846 847 q->flush_flags = flush & (REQ_FLUSH | REQ_FUA); 848 } 849 EXPORT_SYMBOL_GPL(blk_queue_flush); 850 851 void blk_queue_flush_queueable(struct request_queue *q, bool queueable) 852 { 853 q->flush_not_queueable = !queueable; 854 } 855 EXPORT_SYMBOL_GPL(blk_queue_flush_queueable); 856 857 static int __init blk_settings_init(void) 858 { 859 blk_max_low_pfn = max_low_pfn - 1; 860 blk_max_pfn = max_pfn - 1; 861 return 0; 862 } 863 subsys_initcall(blk_settings_init); 864