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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
17unsigned long blk_max_low_pfn;
18EXPORT_SYMBOL(blk_max_low_pfn);
19
20unsigned 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 */
33void blk_queue_prep_rq(struct request_queue *q, prep_rq_fn *pfn)
34{
35 q->prep_rq_fn = pfn;
36}
37EXPORT_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 */
50void blk_queue_unprep_rq(struct request_queue *q, unprep_rq_fn *ufn)
51{
52 q->unprep_rq_fn = ufn;
53}
54EXPORT_SYMBOL(blk_queue_unprep_rq);
55
56void blk_queue_softirq_done(struct request_queue *q, softirq_done_fn *fn)
57{
58 q->softirq_done_fn = fn;
59}
60EXPORT_SYMBOL(blk_queue_softirq_done);
61
62void blk_queue_rq_timeout(struct request_queue *q, unsigned int timeout)
63{
64 q->rq_timeout = timeout;
65}
66EXPORT_SYMBOL_GPL(blk_queue_rq_timeout);
67
68void blk_queue_rq_timed_out(struct request_queue *q, rq_timed_out_fn *fn)
69{
70 q->rq_timed_out_fn = fn;
71}
72EXPORT_SYMBOL_GPL(blk_queue_rq_timed_out);
73
74void blk_queue_lld_busy(struct request_queue *q, lld_busy_fn *fn)
75{
76 q->lld_busy_fn = fn;
77}
78EXPORT_SYMBOL_GPL(blk_queue_lld_busy);
79
80/**
81 * blk_set_default_limits - reset limits to default values
82 * @lim: the queue_limits structure to reset
83 *
84 * Description:
85 * Returns a queue_limit struct to its default state.
86 */
87void blk_set_default_limits(struct queue_limits *lim)
88{
89 lim->max_segments = BLK_MAX_SEGMENTS;
90 lim->max_integrity_segments = 0;
91 lim->seg_boundary_mask = BLK_SEG_BOUNDARY_MASK;
92 lim->virt_boundary_mask = 0;
93 lim->max_segment_size = BLK_MAX_SEGMENT_SIZE;
94 lim->max_sectors = lim->max_hw_sectors = BLK_SAFE_MAX_SECTORS;
95 lim->max_dev_sectors = 0;
96 lim->chunk_sectors = 0;
97 lim->max_write_same_sectors = 0;
98 lim->max_discard_sectors = 0;
99 lim->max_hw_discard_sectors = 0;
100 lim->discard_granularity = 0;
101 lim->discard_alignment = 0;
102 lim->discard_misaligned = 0;
103 lim->discard_zeroes_data = 0;
104 lim->logical_block_size = lim->physical_block_size = lim->io_min = 512;
105 lim->bounce_pfn = (unsigned long)(BLK_BOUNCE_ANY >> PAGE_SHIFT);
106 lim->alignment_offset = 0;
107 lim->io_opt = 0;
108 lim->misaligned = 0;
109 lim->cluster = 1;
110}
111EXPORT_SYMBOL(blk_set_default_limits);
112
113/**
114 * blk_set_stacking_limits - set default limits for stacking devices
115 * @lim: the queue_limits structure to reset
116 *
117 * Description:
118 * Returns a queue_limit struct to its default state. Should be used
119 * by stacking drivers like DM that have no internal limits.
120 */
121void blk_set_stacking_limits(struct queue_limits *lim)
122{
123 blk_set_default_limits(lim);
124
125 /* Inherit limits from component devices */
126 lim->discard_zeroes_data = 1;
127 lim->max_segments = USHRT_MAX;
128 lim->max_hw_sectors = UINT_MAX;
129 lim->max_segment_size = UINT_MAX;
130 lim->max_sectors = UINT_MAX;
131 lim->max_dev_sectors = UINT_MAX;
132 lim->max_write_same_sectors = UINT_MAX;
133}
134EXPORT_SYMBOL(blk_set_stacking_limits);
135
136/**
137 * blk_queue_make_request - define an alternate make_request function for a device
138 * @q: the request queue for the device to be affected
139 * @mfn: the alternate make_request function
140 *
141 * Description:
142 * The normal way for &struct bios to be passed to a device
143 * driver is for them to be collected into requests on a request
144 * queue, and then to allow the device driver to select requests
145 * off that queue when it is ready. This works well for many block
146 * devices. However some block devices (typically virtual devices
147 * such as md or lvm) do not benefit from the processing on the
148 * request queue, and are served best by having the requests passed
149 * directly to them. This can be achieved by providing a function
150 * to blk_queue_make_request().
151 *
152 * Caveat:
153 * The driver that does this *must* be able to deal appropriately
154 * with buffers in "highmemory". This can be accomplished by either calling
155 * __bio_kmap_atomic() to get a temporary kernel mapping, or by calling
156 * blk_queue_bounce() to create a buffer in normal memory.
157 **/
158void blk_queue_make_request(struct request_queue *q, make_request_fn *mfn)
159{
160 /*
161 * set defaults
162 */
163 q->nr_requests = BLKDEV_MAX_RQ;
164
165 q->make_request_fn = mfn;
166 blk_queue_dma_alignment(q, 511);
167 blk_queue_congestion_threshold(q);
168 q->nr_batching = BLK_BATCH_REQ;
169
170 blk_set_default_limits(&q->limits);
171
172 /*
173 * by default assume old behaviour and bounce for any highmem page
174 */
175 blk_queue_bounce_limit(q, BLK_BOUNCE_HIGH);
176}
177EXPORT_SYMBOL(blk_queue_make_request);
178
179/**
180 * blk_queue_bounce_limit - set bounce buffer limit for queue
181 * @q: the request queue for the device
182 * @max_addr: the maximum address the device can handle
183 *
184 * Description:
185 * Different hardware can have different requirements as to what pages
186 * it can do I/O directly to. A low level driver can call
187 * blk_queue_bounce_limit to have lower memory pages allocated as bounce
188 * buffers for doing I/O to pages residing above @max_addr.
189 **/
190void blk_queue_bounce_limit(struct request_queue *q, u64 max_addr)
191{
192 unsigned long b_pfn = max_addr >> PAGE_SHIFT;
193 int dma = 0;
194
195 q->bounce_gfp = GFP_NOIO;
196#if BITS_PER_LONG == 64
197 /*
198 * Assume anything <= 4GB can be handled by IOMMU. Actually
199 * some IOMMUs can handle everything, but I don't know of a
200 * way to test this here.
201 */
202 if (b_pfn < (min_t(u64, 0xffffffffUL, BLK_BOUNCE_HIGH) >> PAGE_SHIFT))
203 dma = 1;
204 q->limits.bounce_pfn = max(max_low_pfn, b_pfn);
205#else
206 if (b_pfn < blk_max_low_pfn)
207 dma = 1;
208 q->limits.bounce_pfn = b_pfn;
209#endif
210 if (dma) {
211 init_emergency_isa_pool();
212 q->bounce_gfp = GFP_NOIO | GFP_DMA;
213 q->limits.bounce_pfn = b_pfn;
214 }
215}
216EXPORT_SYMBOL(blk_queue_bounce_limit);
217
218/**
219 * blk_queue_max_hw_sectors - set max sectors for a request for this queue
220 * @q: the request queue for the device
221 * @max_hw_sectors: max hardware sectors in the usual 512b unit
222 *
223 * Description:
224 * Enables a low level driver to set a hard upper limit,
225 * max_hw_sectors, on the size of requests. max_hw_sectors is set by
226 * the device driver based upon the capabilities of the I/O
227 * controller.
228 *
229 * max_dev_sectors is a hard limit imposed by the storage device for
230 * READ/WRITE requests. It is set by the disk driver.
231 *
232 * max_sectors is a soft limit imposed by the block layer for
233 * filesystem type requests. This value can be overridden on a
234 * per-device basis in /sys/block/<device>/queue/max_sectors_kb.
235 * The soft limit can not exceed max_hw_sectors.
236 **/
237void blk_queue_max_hw_sectors(struct request_queue *q, unsigned int max_hw_sectors)
238{
239 struct queue_limits *limits = &q->limits;
240 unsigned int max_sectors;
241
242 if ((max_hw_sectors << 9) < PAGE_SIZE) {
243 max_hw_sectors = 1 << (PAGE_SHIFT - 9);
244 printk(KERN_INFO "%s: set to minimum %d\n",
245 __func__, max_hw_sectors);
246 }
247
248 limits->max_hw_sectors = max_hw_sectors;
249 max_sectors = min_not_zero(max_hw_sectors, limits->max_dev_sectors);
250 max_sectors = min_t(unsigned int, max_sectors, BLK_DEF_MAX_SECTORS);
251 limits->max_sectors = max_sectors;
252}
253EXPORT_SYMBOL(blk_queue_max_hw_sectors);
254
255/**
256 * blk_queue_chunk_sectors - set size of the chunk for this queue
257 * @q: the request queue for the device
258 * @chunk_sectors: chunk sectors in the usual 512b unit
259 *
260 * Description:
261 * If a driver doesn't want IOs to cross a given chunk size, it can set
262 * this limit and prevent merging across chunks. Note that the chunk size
263 * must currently be a power-of-2 in sectors. Also note that the block
264 * layer must accept a page worth of data at any offset. So if the
265 * crossing of chunks is a hard limitation in the driver, it must still be
266 * prepared to split single page bios.
267 **/
268void blk_queue_chunk_sectors(struct request_queue *q, unsigned int chunk_sectors)
269{
270 BUG_ON(!is_power_of_2(chunk_sectors));
271 q->limits.chunk_sectors = chunk_sectors;
272}
273EXPORT_SYMBOL(blk_queue_chunk_sectors);
274
275/**
276 * blk_queue_max_discard_sectors - set max sectors for a single discard
277 * @q: the request queue for the device
278 * @max_discard_sectors: maximum number of sectors to discard
279 **/
280void blk_queue_max_discard_sectors(struct request_queue *q,
281 unsigned int max_discard_sectors)
282{
283 q->limits.max_hw_discard_sectors = max_discard_sectors;
284 q->limits.max_discard_sectors = max_discard_sectors;
285}
286EXPORT_SYMBOL(blk_queue_max_discard_sectors);
287
288/**
289 * blk_queue_max_write_same_sectors - set max sectors for a single write same
290 * @q: the request queue for the device
291 * @max_write_same_sectors: maximum number of sectors to write per command
292 **/
293void blk_queue_max_write_same_sectors(struct request_queue *q,
294 unsigned int max_write_same_sectors)
295{
296 q->limits.max_write_same_sectors = max_write_same_sectors;
297}
298EXPORT_SYMBOL(blk_queue_max_write_same_sectors);
299
300/**
301 * blk_queue_max_segments - set max hw segments for a request for this queue
302 * @q: the request queue for the device
303 * @max_segments: max number of segments
304 *
305 * Description:
306 * Enables a low level driver to set an upper limit on the number of
307 * hw data segments in a request.
308 **/
309void blk_queue_max_segments(struct request_queue *q, unsigned short max_segments)
310{
311 if (!max_segments) {
312 max_segments = 1;
313 printk(KERN_INFO "%s: set to minimum %d\n",
314 __func__, max_segments);
315 }
316
317 q->limits.max_segments = max_segments;
318}
319EXPORT_SYMBOL(blk_queue_max_segments);
320
321/**
322 * blk_queue_max_segment_size - set max segment size for blk_rq_map_sg
323 * @q: the request queue for the device
324 * @max_size: max size of segment in bytes
325 *
326 * Description:
327 * Enables a low level driver to set an upper limit on the size of a
328 * coalesced segment
329 **/
330void blk_queue_max_segment_size(struct request_queue *q, unsigned int max_size)
331{
332 if (max_size < PAGE_SIZE) {
333 max_size = PAGE_SIZE;
334 printk(KERN_INFO "%s: set to minimum %d\n",
335 __func__, max_size);
336 }
337
338 q->limits.max_segment_size = max_size;
339}
340EXPORT_SYMBOL(blk_queue_max_segment_size);
341
342/**
343 * blk_queue_logical_block_size - set logical block size for the queue
344 * @q: the request queue for the device
345 * @size: the logical block size, in bytes
346 *
347 * Description:
348 * This should be set to the lowest possible block size that the
349 * storage device can address. The default of 512 covers most
350 * hardware.
351 **/
352void blk_queue_logical_block_size(struct request_queue *q, unsigned short size)
353{
354 q->limits.logical_block_size = size;
355
356 if (q->limits.physical_block_size < size)
357 q->limits.physical_block_size = size;
358
359 if (q->limits.io_min < q->limits.physical_block_size)
360 q->limits.io_min = q->limits.physical_block_size;
361}
362EXPORT_SYMBOL(blk_queue_logical_block_size);
363
364/**
365 * blk_queue_physical_block_size - set physical block size for the queue
366 * @q: the request queue for the device
367 * @size: the physical block size, in bytes
368 *
369 * Description:
370 * This should be set to the lowest possible sector size that the
371 * hardware can operate on without reverting to read-modify-write
372 * operations.
373 */
374void blk_queue_physical_block_size(struct request_queue *q, unsigned int size)
375{
376 q->limits.physical_block_size = size;
377
378 if (q->limits.physical_block_size < q->limits.logical_block_size)
379 q->limits.physical_block_size = q->limits.logical_block_size;
380
381 if (q->limits.io_min < q->limits.physical_block_size)
382 q->limits.io_min = q->limits.physical_block_size;
383}
384EXPORT_SYMBOL(blk_queue_physical_block_size);
385
386/**
387 * blk_queue_alignment_offset - set physical block alignment offset
388 * @q: the request queue for the device
389 * @offset: alignment offset in bytes
390 *
391 * Description:
392 * Some devices are naturally misaligned to compensate for things like
393 * the legacy DOS partition table 63-sector offset. Low-level drivers
394 * should call this function for devices whose first sector is not
395 * naturally aligned.
396 */
397void blk_queue_alignment_offset(struct request_queue *q, unsigned int offset)
398{
399 q->limits.alignment_offset =
400 offset & (q->limits.physical_block_size - 1);
401 q->limits.misaligned = 0;
402}
403EXPORT_SYMBOL(blk_queue_alignment_offset);
404
405/**
406 * blk_limits_io_min - set minimum request size for a device
407 * @limits: the queue limits
408 * @min: smallest I/O size in bytes
409 *
410 * Description:
411 * Some devices have an internal block size bigger than the reported
412 * hardware sector size. This function can be used to signal the
413 * smallest I/O the device can perform without incurring a performance
414 * penalty.
415 */
416void blk_limits_io_min(struct queue_limits *limits, unsigned int min)
417{
418 limits->io_min = min;
419
420 if (limits->io_min < limits->logical_block_size)
421 limits->io_min = limits->logical_block_size;
422
423 if (limits->io_min < limits->physical_block_size)
424 limits->io_min = limits->physical_block_size;
425}
426EXPORT_SYMBOL(blk_limits_io_min);
427
428/**
429 * blk_queue_io_min - set minimum request size for the queue
430 * @q: the request queue for the device
431 * @min: smallest I/O size in bytes
432 *
433 * Description:
434 * Storage devices may report a granularity or preferred minimum I/O
435 * size which is the smallest request the device can perform without
436 * incurring a performance penalty. For disk drives this is often the
437 * physical block size. For RAID arrays it is often the stripe chunk
438 * size. A properly aligned multiple of minimum_io_size is the
439 * preferred request size for workloads where a high number of I/O
440 * operations is desired.
441 */
442void blk_queue_io_min(struct request_queue *q, unsigned int min)
443{
444 blk_limits_io_min(&q->limits, min);
445}
446EXPORT_SYMBOL(blk_queue_io_min);
447
448/**
449 * blk_limits_io_opt - set optimal request size for a device
450 * @limits: the queue limits
451 * @opt: smallest I/O size in bytes
452 *
453 * Description:
454 * Storage devices may report an optimal I/O size, which is the
455 * device's preferred unit for sustained I/O. This is rarely reported
456 * for disk drives. For RAID arrays it is usually the stripe width or
457 * the internal track size. A properly aligned multiple of
458 * optimal_io_size is the preferred request size for workloads where
459 * sustained throughput is desired.
460 */
461void blk_limits_io_opt(struct queue_limits *limits, unsigned int opt)
462{
463 limits->io_opt = opt;
464}
465EXPORT_SYMBOL(blk_limits_io_opt);
466
467/**
468 * blk_queue_io_opt - set optimal request size for the queue
469 * @q: the request queue for the device
470 * @opt: optimal request size in bytes
471 *
472 * Description:
473 * Storage devices may report an optimal I/O size, which is the
474 * device's preferred unit for sustained I/O. This is rarely reported
475 * for disk drives. For RAID arrays it is usually the stripe width or
476 * the internal track size. A properly aligned multiple of
477 * optimal_io_size is the preferred request size for workloads where
478 * sustained throughput is desired.
479 */
480void blk_queue_io_opt(struct request_queue *q, unsigned int opt)
481{
482 blk_limits_io_opt(&q->limits, opt);
483}
484EXPORT_SYMBOL(blk_queue_io_opt);
485
486/**
487 * blk_queue_stack_limits - inherit underlying queue limits for stacked drivers
488 * @t: the stacking driver (top)
489 * @b: the underlying device (bottom)
490 **/
491void blk_queue_stack_limits(struct request_queue *t, struct request_queue *b)
492{
493 blk_stack_limits(&t->limits, &b->limits, 0);
494}
495EXPORT_SYMBOL(blk_queue_stack_limits);
496
497/**
498 * blk_stack_limits - adjust queue_limits for stacked devices
499 * @t: the stacking driver limits (top device)
500 * @b: the underlying queue limits (bottom, component device)
501 * @start: first data sector within component device
502 *
503 * Description:
504 * This function is used by stacking drivers like MD and DM to ensure
505 * that all component devices have compatible block sizes and
506 * alignments. The stacking driver must provide a queue_limits
507 * struct (top) and then iteratively call the stacking function for
508 * all component (bottom) devices. The stacking function will
509 * attempt to combine the values and ensure proper alignment.
510 *
511 * Returns 0 if the top and bottom queue_limits are compatible. The
512 * top device's block sizes and alignment offsets may be adjusted to
513 * ensure alignment with the bottom device. If no compatible sizes
514 * and alignments exist, -1 is returned and the resulting top
515 * queue_limits will have the misaligned flag set to indicate that
516 * the alignment_offset is undefined.
517 */
518int blk_stack_limits(struct queue_limits *t, struct queue_limits *b,
519 sector_t start)
520{
521 unsigned int top, bottom, alignment, ret = 0;
522
523 t->max_sectors = min_not_zero(t->max_sectors, b->max_sectors);
524 t->max_hw_sectors = min_not_zero(t->max_hw_sectors, b->max_hw_sectors);
525 t->max_dev_sectors = min_not_zero(t->max_dev_sectors, b->max_dev_sectors);
526 t->max_write_same_sectors = min(t->max_write_same_sectors,
527 b->max_write_same_sectors);
528 t->bounce_pfn = min_not_zero(t->bounce_pfn, b->bounce_pfn);
529
530 t->seg_boundary_mask = min_not_zero(t->seg_boundary_mask,
531 b->seg_boundary_mask);
532 t->virt_boundary_mask = min_not_zero(t->virt_boundary_mask,
533 b->virt_boundary_mask);
534
535 t->max_segments = min_not_zero(t->max_segments, b->max_segments);
536 t->max_integrity_segments = min_not_zero(t->max_integrity_segments,
537 b->max_integrity_segments);
538
539 t->max_segment_size = min_not_zero(t->max_segment_size,
540 b->max_segment_size);
541
542 t->misaligned |= b->misaligned;
543
544 alignment = queue_limit_alignment_offset(b, start);
545
546 /* Bottom device has different alignment. Check that it is
547 * compatible with the current top alignment.
548 */
549 if (t->alignment_offset != alignment) {
550
551 top = max(t->physical_block_size, t->io_min)
552 + t->alignment_offset;
553 bottom = max(b->physical_block_size, b->io_min) + alignment;
554
555 /* Verify that top and bottom intervals line up */
556 if (max(top, bottom) % min(top, bottom)) {
557 t->misaligned = 1;
558 ret = -1;
559 }
560 }
561
562 t->logical_block_size = max(t->logical_block_size,
563 b->logical_block_size);
564
565 t->physical_block_size = max(t->physical_block_size,
566 b->physical_block_size);
567
568 t->io_min = max(t->io_min, b->io_min);
569 t->io_opt = lcm_not_zero(t->io_opt, b->io_opt);
570
571 t->cluster &= b->cluster;
572 t->discard_zeroes_data &= b->discard_zeroes_data;
573
574 /* Physical block size a multiple of the logical block size? */
575 if (t->physical_block_size & (t->logical_block_size - 1)) {
576 t->physical_block_size = t->logical_block_size;
577 t->misaligned = 1;
578 ret = -1;
579 }
580
581 /* Minimum I/O a multiple of the physical block size? */
582 if (t->io_min & (t->physical_block_size - 1)) {
583 t->io_min = t->physical_block_size;
584 t->misaligned = 1;
585 ret = -1;
586 }
587
588 /* Optimal I/O a multiple of the physical block size? */
589 if (t->io_opt & (t->physical_block_size - 1)) {
590 t->io_opt = 0;
591 t->misaligned = 1;
592 ret = -1;
593 }
594
595 t->raid_partial_stripes_expensive =
596 max(t->raid_partial_stripes_expensive,
597 b->raid_partial_stripes_expensive);
598
599 /* Find lowest common alignment_offset */
600 t->alignment_offset = lcm_not_zero(t->alignment_offset, alignment)
601 % max(t->physical_block_size, t->io_min);
602
603 /* Verify that new alignment_offset is on a logical block boundary */
604 if (t->alignment_offset & (t->logical_block_size - 1)) {
605 t->misaligned = 1;
606 ret = -1;
607 }
608
609 /* Discard alignment and granularity */
610 if (b->discard_granularity) {
611 alignment = queue_limit_discard_alignment(b, start);
612
613 if (t->discard_granularity != 0 &&
614 t->discard_alignment != alignment) {
615 top = t->discard_granularity + t->discard_alignment;
616 bottom = b->discard_granularity + alignment;
617
618 /* Verify that top and bottom intervals line up */
619 if ((max(top, bottom) % min(top, bottom)) != 0)
620 t->discard_misaligned = 1;
621 }
622
623 t->max_discard_sectors = min_not_zero(t->max_discard_sectors,
624 b->max_discard_sectors);
625 t->max_hw_discard_sectors = min_not_zero(t->max_hw_discard_sectors,
626 b->max_hw_discard_sectors);
627 t->discard_granularity = max(t->discard_granularity,
628 b->discard_granularity);
629 t->discard_alignment = lcm_not_zero(t->discard_alignment, alignment) %
630 t->discard_granularity;
631 }
632
633 return ret;
634}
635EXPORT_SYMBOL(blk_stack_limits);
636
637/**
638 * bdev_stack_limits - adjust queue limits for stacked drivers
639 * @t: the stacking driver limits (top device)
640 * @bdev: the component block_device (bottom)
641 * @start: first data sector within component device
642 *
643 * Description:
644 * Merges queue limits for a top device and a block_device. Returns
645 * 0 if alignment didn't change. Returns -1 if adding the bottom
646 * device caused misalignment.
647 */
648int bdev_stack_limits(struct queue_limits *t, struct block_device *bdev,
649 sector_t start)
650{
651 struct request_queue *bq = bdev_get_queue(bdev);
652
653 start += get_start_sect(bdev);
654
655 return blk_stack_limits(t, &bq->limits, start);
656}
657EXPORT_SYMBOL(bdev_stack_limits);
658
659/**
660 * disk_stack_limits - adjust queue limits for stacked drivers
661 * @disk: MD/DM gendisk (top)
662 * @bdev: the underlying block device (bottom)
663 * @offset: offset to beginning of data within component device
664 *
665 * Description:
666 * Merges the limits for a top level gendisk and a bottom level
667 * block_device.
668 */
669void disk_stack_limits(struct gendisk *disk, struct block_device *bdev,
670 sector_t offset)
671{
672 struct request_queue *t = disk->queue;
673
674 if (bdev_stack_limits(&t->limits, bdev, offset >> 9) < 0) {
675 char top[BDEVNAME_SIZE], bottom[BDEVNAME_SIZE];
676
677 disk_name(disk, 0, top);
678 bdevname(bdev, bottom);
679
680 printk(KERN_NOTICE "%s: Warning: Device %s is misaligned\n",
681 top, bottom);
682 }
683}
684EXPORT_SYMBOL(disk_stack_limits);
685
686/**
687 * blk_queue_dma_pad - set pad mask
688 * @q: the request queue for the device
689 * @mask: pad mask
690 *
691 * Set dma pad mask.
692 *
693 * Appending pad buffer to a request modifies the last entry of a
694 * scatter list such that it includes the pad buffer.
695 **/
696void blk_queue_dma_pad(struct request_queue *q, unsigned int mask)
697{
698 q->dma_pad_mask = mask;
699}
700EXPORT_SYMBOL(blk_queue_dma_pad);
701
702/**
703 * blk_queue_update_dma_pad - update pad mask
704 * @q: the request queue for the device
705 * @mask: pad mask
706 *
707 * Update dma pad mask.
708 *
709 * Appending pad buffer to a request modifies the last entry of a
710 * scatter list such that it includes the pad buffer.
711 **/
712void blk_queue_update_dma_pad(struct request_queue *q, unsigned int mask)
713{
714 if (mask > q->dma_pad_mask)
715 q->dma_pad_mask = mask;
716}
717EXPORT_SYMBOL(blk_queue_update_dma_pad);
718
719/**
720 * blk_queue_dma_drain - Set up a drain buffer for excess dma.
721 * @q: the request queue for the device
722 * @dma_drain_needed: fn which returns non-zero if drain is necessary
723 * @buf: physically contiguous buffer
724 * @size: size of the buffer in bytes
725 *
726 * Some devices have excess DMA problems and can't simply discard (or
727 * zero fill) the unwanted piece of the transfer. They have to have a
728 * real area of memory to transfer it into. The use case for this is
729 * ATAPI devices in DMA mode. If the packet command causes a transfer
730 * bigger than the transfer size some HBAs will lock up if there
731 * aren't DMA elements to contain the excess transfer. What this API
732 * does is adjust the queue so that the buf is always appended
733 * silently to the scatterlist.
734 *
735 * Note: This routine adjusts max_hw_segments to make room for appending
736 * the drain buffer. If you call blk_queue_max_segments() after calling
737 * this routine, you must set the limit to one fewer than your device
738 * can support otherwise there won't be room for the drain buffer.
739 */
740int blk_queue_dma_drain(struct request_queue *q,
741 dma_drain_needed_fn *dma_drain_needed,
742 void *buf, unsigned int size)
743{
744 if (queue_max_segments(q) < 2)
745 return -EINVAL;
746 /* make room for appending the drain */
747 blk_queue_max_segments(q, queue_max_segments(q) - 1);
748 q->dma_drain_needed = dma_drain_needed;
749 q->dma_drain_buffer = buf;
750 q->dma_drain_size = size;
751
752 return 0;
753}
754EXPORT_SYMBOL_GPL(blk_queue_dma_drain);
755
756/**
757 * blk_queue_segment_boundary - set boundary rules for segment merging
758 * @q: the request queue for the device
759 * @mask: the memory boundary mask
760 **/
761void blk_queue_segment_boundary(struct request_queue *q, unsigned long mask)
762{
763 if (mask < PAGE_SIZE - 1) {
764 mask = PAGE_SIZE - 1;
765 printk(KERN_INFO "%s: set to minimum %lx\n",
766 __func__, mask);
767 }
768
769 q->limits.seg_boundary_mask = mask;
770}
771EXPORT_SYMBOL(blk_queue_segment_boundary);
772
773/**
774 * blk_queue_virt_boundary - set boundary rules for bio merging
775 * @q: the request queue for the device
776 * @mask: the memory boundary mask
777 **/
778void blk_queue_virt_boundary(struct request_queue *q, unsigned long mask)
779{
780 q->limits.virt_boundary_mask = mask;
781}
782EXPORT_SYMBOL(blk_queue_virt_boundary);
783
784/**
785 * blk_queue_dma_alignment - set dma length and memory alignment
786 * @q: the request queue for the device
787 * @mask: alignment mask
788 *
789 * description:
790 * set required memory and length alignment for direct dma transactions.
791 * this is used when building direct io requests for the queue.
792 *
793 **/
794void blk_queue_dma_alignment(struct request_queue *q, int mask)
795{
796 q->dma_alignment = mask;
797}
798EXPORT_SYMBOL(blk_queue_dma_alignment);
799
800/**
801 * blk_queue_update_dma_alignment - update dma length and memory alignment
802 * @q: the request queue for the device
803 * @mask: alignment mask
804 *
805 * description:
806 * update required memory and length alignment for direct dma transactions.
807 * If the requested alignment is larger than the current alignment, then
808 * the current queue alignment is updated to the new value, otherwise it
809 * is left alone. The design of this is to allow multiple objects
810 * (driver, device, transport etc) to set their respective
811 * alignments without having them interfere.
812 *
813 **/
814void blk_queue_update_dma_alignment(struct request_queue *q, int mask)
815{
816 BUG_ON(mask > PAGE_SIZE);
817
818 if (mask > q->dma_alignment)
819 q->dma_alignment = mask;
820}
821EXPORT_SYMBOL(blk_queue_update_dma_alignment);
822
823/**
824 * blk_queue_flush - configure queue's cache flush capability
825 * @q: the request queue for the device
826 * @flush: 0, REQ_FLUSH or REQ_FLUSH | REQ_FUA
827 *
828 * Tell block layer cache flush capability of @q. If it supports
829 * flushing, REQ_FLUSH should be set. If it supports bypassing
830 * write cache for individual writes, REQ_FUA should be set.
831 */
832void blk_queue_flush(struct request_queue *q, unsigned int flush)
833{
834 WARN_ON_ONCE(flush & ~(REQ_FLUSH | REQ_FUA));
835
836 if (WARN_ON_ONCE(!(flush & REQ_FLUSH) && (flush & REQ_FUA)))
837 flush &= ~REQ_FUA;
838
839 q->flush_flags = flush & (REQ_FLUSH | REQ_FUA);
840}
841EXPORT_SYMBOL_GPL(blk_queue_flush);
842
843void blk_queue_flush_queueable(struct request_queue *q, bool queueable)
844{
845 q->flush_not_queueable = !queueable;
846}
847EXPORT_SYMBOL_GPL(blk_queue_flush_queueable);
848
849static int __init blk_settings_init(void)
850{
851 blk_max_low_pfn = max_low_pfn - 1;
852 blk_max_pfn = max_pfn - 1;
853 return 0;
854}
855subsys_initcall(blk_settings_init);
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#include <linux/dma-mapping.h>
16
17#include "blk.h"
18#include "blk-wbt.h"
19
20unsigned long blk_max_low_pfn;
21EXPORT_SYMBOL(blk_max_low_pfn);
22
23unsigned long blk_max_pfn;
24
25void blk_queue_rq_timeout(struct request_queue *q, unsigned int timeout)
26{
27 q->rq_timeout = timeout;
28}
29EXPORT_SYMBOL_GPL(blk_queue_rq_timeout);
30
31/**
32 * blk_set_default_limits - reset limits to default values
33 * @lim: the queue_limits structure to reset
34 *
35 * Description:
36 * Returns a queue_limit struct to its default state.
37 */
38void blk_set_default_limits(struct queue_limits *lim)
39{
40 lim->max_segments = BLK_MAX_SEGMENTS;
41 lim->max_discard_segments = 1;
42 lim->max_integrity_segments = 0;
43 lim->seg_boundary_mask = BLK_SEG_BOUNDARY_MASK;
44 lim->virt_boundary_mask = 0;
45 lim->max_segment_size = BLK_MAX_SEGMENT_SIZE;
46 lim->max_sectors = lim->max_hw_sectors = BLK_SAFE_MAX_SECTORS;
47 lim->max_dev_sectors = 0;
48 lim->chunk_sectors = 0;
49 lim->max_write_same_sectors = 0;
50 lim->max_write_zeroes_sectors = 0;
51 lim->max_zone_append_sectors = 0;
52 lim->max_discard_sectors = 0;
53 lim->max_hw_discard_sectors = 0;
54 lim->discard_granularity = 0;
55 lim->discard_alignment = 0;
56 lim->discard_misaligned = 0;
57 lim->logical_block_size = lim->physical_block_size = lim->io_min = 512;
58 lim->bounce_pfn = (unsigned long)(BLK_BOUNCE_ANY >> PAGE_SHIFT);
59 lim->alignment_offset = 0;
60 lim->io_opt = 0;
61 lim->misaligned = 0;
62 lim->zoned = BLK_ZONED_NONE;
63}
64EXPORT_SYMBOL(blk_set_default_limits);
65
66/**
67 * blk_set_stacking_limits - set default limits for stacking devices
68 * @lim: the queue_limits structure to reset
69 *
70 * Description:
71 * Returns a queue_limit struct to its default state. Should be used
72 * by stacking drivers like DM that have no internal limits.
73 */
74void blk_set_stacking_limits(struct queue_limits *lim)
75{
76 blk_set_default_limits(lim);
77
78 /* Inherit limits from component devices */
79 lim->max_segments = USHRT_MAX;
80 lim->max_discard_segments = USHRT_MAX;
81 lim->max_hw_sectors = UINT_MAX;
82 lim->max_segment_size = UINT_MAX;
83 lim->max_sectors = UINT_MAX;
84 lim->max_dev_sectors = UINT_MAX;
85 lim->max_write_same_sectors = UINT_MAX;
86 lim->max_write_zeroes_sectors = UINT_MAX;
87 lim->max_zone_append_sectors = UINT_MAX;
88}
89EXPORT_SYMBOL(blk_set_stacking_limits);
90
91/**
92 * blk_queue_bounce_limit - set bounce buffer limit for queue
93 * @q: the request queue for the device
94 * @max_addr: the maximum address the device can handle
95 *
96 * Description:
97 * Different hardware can have different requirements as to what pages
98 * it can do I/O directly to. A low level driver can call
99 * blk_queue_bounce_limit to have lower memory pages allocated as bounce
100 * buffers for doing I/O to pages residing above @max_addr.
101 **/
102void blk_queue_bounce_limit(struct request_queue *q, u64 max_addr)
103{
104 unsigned long b_pfn = max_addr >> PAGE_SHIFT;
105 int dma = 0;
106
107 q->bounce_gfp = GFP_NOIO;
108#if BITS_PER_LONG == 64
109 /*
110 * Assume anything <= 4GB can be handled by IOMMU. Actually
111 * some IOMMUs can handle everything, but I don't know of a
112 * way to test this here.
113 */
114 if (b_pfn < (min_t(u64, 0xffffffffUL, BLK_BOUNCE_HIGH) >> PAGE_SHIFT))
115 dma = 1;
116 q->limits.bounce_pfn = max(max_low_pfn, b_pfn);
117#else
118 if (b_pfn < blk_max_low_pfn)
119 dma = 1;
120 q->limits.bounce_pfn = b_pfn;
121#endif
122 if (dma) {
123 init_emergency_isa_pool();
124 q->bounce_gfp = GFP_NOIO | GFP_DMA;
125 q->limits.bounce_pfn = b_pfn;
126 }
127}
128EXPORT_SYMBOL(blk_queue_bounce_limit);
129
130/**
131 * blk_queue_max_hw_sectors - set max sectors for a request for this queue
132 * @q: the request queue for the device
133 * @max_hw_sectors: max hardware sectors in the usual 512b unit
134 *
135 * Description:
136 * Enables a low level driver to set a hard upper limit,
137 * max_hw_sectors, on the size of requests. max_hw_sectors is set by
138 * the device driver based upon the capabilities of the I/O
139 * controller.
140 *
141 * max_dev_sectors is a hard limit imposed by the storage device for
142 * READ/WRITE requests. It is set by the disk driver.
143 *
144 * max_sectors is a soft limit imposed by the block layer for
145 * filesystem type requests. This value can be overridden on a
146 * per-device basis in /sys/block/<device>/queue/max_sectors_kb.
147 * The soft limit can not exceed max_hw_sectors.
148 **/
149void blk_queue_max_hw_sectors(struct request_queue *q, unsigned int max_hw_sectors)
150{
151 struct queue_limits *limits = &q->limits;
152 unsigned int max_sectors;
153
154 if ((max_hw_sectors << 9) < PAGE_SIZE) {
155 max_hw_sectors = 1 << (PAGE_SHIFT - 9);
156 printk(KERN_INFO "%s: set to minimum %d\n",
157 __func__, max_hw_sectors);
158 }
159
160 limits->max_hw_sectors = max_hw_sectors;
161 max_sectors = min_not_zero(max_hw_sectors, limits->max_dev_sectors);
162 max_sectors = min_t(unsigned int, max_sectors, BLK_DEF_MAX_SECTORS);
163 limits->max_sectors = max_sectors;
164 q->backing_dev_info->io_pages = max_sectors >> (PAGE_SHIFT - 9);
165}
166EXPORT_SYMBOL(blk_queue_max_hw_sectors);
167
168/**
169 * blk_queue_chunk_sectors - set size of the chunk for this queue
170 * @q: the request queue for the device
171 * @chunk_sectors: chunk sectors in the usual 512b unit
172 *
173 * Description:
174 * If a driver doesn't want IOs to cross a given chunk size, it can set
175 * this limit and prevent merging across chunks. Note that the chunk size
176 * must currently be a power-of-2 in sectors. Also note that the block
177 * layer must accept a page worth of data at any offset. So if the
178 * crossing of chunks is a hard limitation in the driver, it must still be
179 * prepared to split single page bios.
180 **/
181void blk_queue_chunk_sectors(struct request_queue *q, unsigned int chunk_sectors)
182{
183 BUG_ON(!is_power_of_2(chunk_sectors));
184 q->limits.chunk_sectors = chunk_sectors;
185}
186EXPORT_SYMBOL(blk_queue_chunk_sectors);
187
188/**
189 * blk_queue_max_discard_sectors - set max sectors for a single discard
190 * @q: the request queue for the device
191 * @max_discard_sectors: maximum number of sectors to discard
192 **/
193void blk_queue_max_discard_sectors(struct request_queue *q,
194 unsigned int max_discard_sectors)
195{
196 q->limits.max_hw_discard_sectors = max_discard_sectors;
197 q->limits.max_discard_sectors = max_discard_sectors;
198}
199EXPORT_SYMBOL(blk_queue_max_discard_sectors);
200
201/**
202 * blk_queue_max_write_same_sectors - set max sectors for a single write same
203 * @q: the request queue for the device
204 * @max_write_same_sectors: maximum number of sectors to write per command
205 **/
206void blk_queue_max_write_same_sectors(struct request_queue *q,
207 unsigned int max_write_same_sectors)
208{
209 q->limits.max_write_same_sectors = max_write_same_sectors;
210}
211EXPORT_SYMBOL(blk_queue_max_write_same_sectors);
212
213/**
214 * blk_queue_max_write_zeroes_sectors - set max sectors for a single
215 * write zeroes
216 * @q: the request queue for the device
217 * @max_write_zeroes_sectors: maximum number of sectors to write per command
218 **/
219void blk_queue_max_write_zeroes_sectors(struct request_queue *q,
220 unsigned int max_write_zeroes_sectors)
221{
222 q->limits.max_write_zeroes_sectors = max_write_zeroes_sectors;
223}
224EXPORT_SYMBOL(blk_queue_max_write_zeroes_sectors);
225
226/**
227 * blk_queue_max_zone_append_sectors - set max sectors for a single zone append
228 * @q: the request queue for the device
229 * @max_zone_append_sectors: maximum number of sectors to write per command
230 **/
231void blk_queue_max_zone_append_sectors(struct request_queue *q,
232 unsigned int max_zone_append_sectors)
233{
234 unsigned int max_sectors;
235
236 if (WARN_ON(!blk_queue_is_zoned(q)))
237 return;
238
239 max_sectors = min(q->limits.max_hw_sectors, max_zone_append_sectors);
240 max_sectors = min(q->limits.chunk_sectors, max_sectors);
241
242 /*
243 * Signal eventual driver bugs resulting in the max_zone_append sectors limit
244 * being 0 due to a 0 argument, the chunk_sectors limit (zone size) not set,
245 * or the max_hw_sectors limit not set.
246 */
247 WARN_ON(!max_sectors);
248
249 q->limits.max_zone_append_sectors = max_sectors;
250}
251EXPORT_SYMBOL_GPL(blk_queue_max_zone_append_sectors);
252
253/**
254 * blk_queue_max_segments - set max hw segments for a request for this queue
255 * @q: the request queue for the device
256 * @max_segments: max number of segments
257 *
258 * Description:
259 * Enables a low level driver to set an upper limit on the number of
260 * hw data segments in a request.
261 **/
262void blk_queue_max_segments(struct request_queue *q, unsigned short max_segments)
263{
264 if (!max_segments) {
265 max_segments = 1;
266 printk(KERN_INFO "%s: set to minimum %d\n",
267 __func__, max_segments);
268 }
269
270 q->limits.max_segments = max_segments;
271}
272EXPORT_SYMBOL(blk_queue_max_segments);
273
274/**
275 * blk_queue_max_discard_segments - set max segments for discard requests
276 * @q: the request queue for the device
277 * @max_segments: max number of segments
278 *
279 * Description:
280 * Enables a low level driver to set an upper limit on the number of
281 * segments in a discard request.
282 **/
283void blk_queue_max_discard_segments(struct request_queue *q,
284 unsigned short max_segments)
285{
286 q->limits.max_discard_segments = max_segments;
287}
288EXPORT_SYMBOL_GPL(blk_queue_max_discard_segments);
289
290/**
291 * blk_queue_max_segment_size - set max segment size for blk_rq_map_sg
292 * @q: the request queue for the device
293 * @max_size: max size of segment in bytes
294 *
295 * Description:
296 * Enables a low level driver to set an upper limit on the size of a
297 * coalesced segment
298 **/
299void blk_queue_max_segment_size(struct request_queue *q, unsigned int max_size)
300{
301 if (max_size < PAGE_SIZE) {
302 max_size = PAGE_SIZE;
303 printk(KERN_INFO "%s: set to minimum %d\n",
304 __func__, max_size);
305 }
306
307 /* see blk_queue_virt_boundary() for the explanation */
308 WARN_ON_ONCE(q->limits.virt_boundary_mask);
309
310 q->limits.max_segment_size = max_size;
311}
312EXPORT_SYMBOL(blk_queue_max_segment_size);
313
314/**
315 * blk_queue_logical_block_size - set logical block size for the queue
316 * @q: the request queue for the device
317 * @size: the logical block size, in bytes
318 *
319 * Description:
320 * This should be set to the lowest possible block size that the
321 * storage device can address. The default of 512 covers most
322 * hardware.
323 **/
324void blk_queue_logical_block_size(struct request_queue *q, unsigned int size)
325{
326 q->limits.logical_block_size = size;
327
328 if (q->limits.physical_block_size < size)
329 q->limits.physical_block_size = size;
330
331 if (q->limits.io_min < q->limits.physical_block_size)
332 q->limits.io_min = q->limits.physical_block_size;
333}
334EXPORT_SYMBOL(blk_queue_logical_block_size);
335
336/**
337 * blk_queue_physical_block_size - set physical block size for the queue
338 * @q: the request queue for the device
339 * @size: the physical block size, in bytes
340 *
341 * Description:
342 * This should be set to the lowest possible sector size that the
343 * hardware can operate on without reverting to read-modify-write
344 * operations.
345 */
346void blk_queue_physical_block_size(struct request_queue *q, unsigned int size)
347{
348 q->limits.physical_block_size = size;
349
350 if (q->limits.physical_block_size < q->limits.logical_block_size)
351 q->limits.physical_block_size = q->limits.logical_block_size;
352
353 if (q->limits.io_min < q->limits.physical_block_size)
354 q->limits.io_min = q->limits.physical_block_size;
355}
356EXPORT_SYMBOL(blk_queue_physical_block_size);
357
358/**
359 * blk_queue_alignment_offset - set physical block alignment offset
360 * @q: the request queue for the device
361 * @offset: alignment offset in bytes
362 *
363 * Description:
364 * Some devices are naturally misaligned to compensate for things like
365 * the legacy DOS partition table 63-sector offset. Low-level drivers
366 * should call this function for devices whose first sector is not
367 * naturally aligned.
368 */
369void blk_queue_alignment_offset(struct request_queue *q, unsigned int offset)
370{
371 q->limits.alignment_offset =
372 offset & (q->limits.physical_block_size - 1);
373 q->limits.misaligned = 0;
374}
375EXPORT_SYMBOL(blk_queue_alignment_offset);
376
377/**
378 * blk_limits_io_min - set minimum request size for a device
379 * @limits: the queue limits
380 * @min: smallest I/O size in bytes
381 *
382 * Description:
383 * Some devices have an internal block size bigger than the reported
384 * hardware sector size. This function can be used to signal the
385 * smallest I/O the device can perform without incurring a performance
386 * penalty.
387 */
388void blk_limits_io_min(struct queue_limits *limits, unsigned int min)
389{
390 limits->io_min = min;
391
392 if (limits->io_min < limits->logical_block_size)
393 limits->io_min = limits->logical_block_size;
394
395 if (limits->io_min < limits->physical_block_size)
396 limits->io_min = limits->physical_block_size;
397}
398EXPORT_SYMBOL(blk_limits_io_min);
399
400/**
401 * blk_queue_io_min - set minimum request size for the queue
402 * @q: the request queue for the device
403 * @min: smallest I/O size in bytes
404 *
405 * Description:
406 * Storage devices may report a granularity or preferred minimum I/O
407 * size which is the smallest request the device can perform without
408 * incurring a performance penalty. For disk drives this is often the
409 * physical block size. For RAID arrays it is often the stripe chunk
410 * size. A properly aligned multiple of minimum_io_size is the
411 * preferred request size for workloads where a high number of I/O
412 * operations is desired.
413 */
414void blk_queue_io_min(struct request_queue *q, unsigned int min)
415{
416 blk_limits_io_min(&q->limits, min);
417}
418EXPORT_SYMBOL(blk_queue_io_min);
419
420/**
421 * blk_limits_io_opt - set optimal request size for a device
422 * @limits: the queue limits
423 * @opt: smallest I/O size in bytes
424 *
425 * Description:
426 * Storage devices may report an optimal I/O size, which is the
427 * device's preferred unit for sustained I/O. This is rarely reported
428 * for disk drives. For RAID arrays it is usually the stripe width or
429 * the internal track size. A properly aligned multiple of
430 * optimal_io_size is the preferred request size for workloads where
431 * sustained throughput is desired.
432 */
433void blk_limits_io_opt(struct queue_limits *limits, unsigned int opt)
434{
435 limits->io_opt = opt;
436}
437EXPORT_SYMBOL(blk_limits_io_opt);
438
439/**
440 * blk_queue_io_opt - set optimal request size for the queue
441 * @q: the request queue for the device
442 * @opt: optimal request size in bytes
443 *
444 * Description:
445 * Storage devices may report an optimal I/O size, which is the
446 * device's preferred unit for sustained I/O. This is rarely reported
447 * for disk drives. For RAID arrays it is usually the stripe width or
448 * the internal track size. A properly aligned multiple of
449 * optimal_io_size is the preferred request size for workloads where
450 * sustained throughput is desired.
451 */
452void blk_queue_io_opt(struct request_queue *q, unsigned int opt)
453{
454 blk_limits_io_opt(&q->limits, opt);
455}
456EXPORT_SYMBOL(blk_queue_io_opt);
457
458/**
459 * blk_stack_limits - adjust queue_limits for stacked devices
460 * @t: the stacking driver limits (top device)
461 * @b: the underlying queue limits (bottom, component device)
462 * @start: first data sector within component device
463 *
464 * Description:
465 * This function is used by stacking drivers like MD and DM to ensure
466 * that all component devices have compatible block sizes and
467 * alignments. The stacking driver must provide a queue_limits
468 * struct (top) and then iteratively call the stacking function for
469 * all component (bottom) devices. The stacking function will
470 * attempt to combine the values and ensure proper alignment.
471 *
472 * Returns 0 if the top and bottom queue_limits are compatible. The
473 * top device's block sizes and alignment offsets may be adjusted to
474 * ensure alignment with the bottom device. If no compatible sizes
475 * and alignments exist, -1 is returned and the resulting top
476 * queue_limits will have the misaligned flag set to indicate that
477 * the alignment_offset is undefined.
478 */
479int blk_stack_limits(struct queue_limits *t, struct queue_limits *b,
480 sector_t start)
481{
482 unsigned int top, bottom, alignment, ret = 0;
483
484 t->max_sectors = min_not_zero(t->max_sectors, b->max_sectors);
485 t->max_hw_sectors = min_not_zero(t->max_hw_sectors, b->max_hw_sectors);
486 t->max_dev_sectors = min_not_zero(t->max_dev_sectors, b->max_dev_sectors);
487 t->max_write_same_sectors = min(t->max_write_same_sectors,
488 b->max_write_same_sectors);
489 t->max_write_zeroes_sectors = min(t->max_write_zeroes_sectors,
490 b->max_write_zeroes_sectors);
491 t->max_zone_append_sectors = min(t->max_zone_append_sectors,
492 b->max_zone_append_sectors);
493 t->bounce_pfn = min_not_zero(t->bounce_pfn, b->bounce_pfn);
494
495 t->seg_boundary_mask = min_not_zero(t->seg_boundary_mask,
496 b->seg_boundary_mask);
497 t->virt_boundary_mask = min_not_zero(t->virt_boundary_mask,
498 b->virt_boundary_mask);
499
500 t->max_segments = min_not_zero(t->max_segments, b->max_segments);
501 t->max_discard_segments = min_not_zero(t->max_discard_segments,
502 b->max_discard_segments);
503 t->max_integrity_segments = min_not_zero(t->max_integrity_segments,
504 b->max_integrity_segments);
505
506 t->max_segment_size = min_not_zero(t->max_segment_size,
507 b->max_segment_size);
508
509 t->misaligned |= b->misaligned;
510
511 alignment = queue_limit_alignment_offset(b, start);
512
513 /* Bottom device has different alignment. Check that it is
514 * compatible with the current top alignment.
515 */
516 if (t->alignment_offset != alignment) {
517
518 top = max(t->physical_block_size, t->io_min)
519 + t->alignment_offset;
520 bottom = max(b->physical_block_size, b->io_min) + alignment;
521
522 /* Verify that top and bottom intervals line up */
523 if (max(top, bottom) % min(top, bottom)) {
524 t->misaligned = 1;
525 ret = -1;
526 }
527 }
528
529 t->logical_block_size = max(t->logical_block_size,
530 b->logical_block_size);
531
532 t->physical_block_size = max(t->physical_block_size,
533 b->physical_block_size);
534
535 t->io_min = max(t->io_min, b->io_min);
536 t->io_opt = lcm_not_zero(t->io_opt, b->io_opt);
537
538 /* Physical block size a multiple of the logical block size? */
539 if (t->physical_block_size & (t->logical_block_size - 1)) {
540 t->physical_block_size = t->logical_block_size;
541 t->misaligned = 1;
542 ret = -1;
543 }
544
545 /* Minimum I/O a multiple of the physical block size? */
546 if (t->io_min & (t->physical_block_size - 1)) {
547 t->io_min = t->physical_block_size;
548 t->misaligned = 1;
549 ret = -1;
550 }
551
552 /* Optimal I/O a multiple of the physical block size? */
553 if (t->io_opt & (t->physical_block_size - 1)) {
554 t->io_opt = 0;
555 t->misaligned = 1;
556 ret = -1;
557 }
558
559 t->raid_partial_stripes_expensive =
560 max(t->raid_partial_stripes_expensive,
561 b->raid_partial_stripes_expensive);
562
563 /* Find lowest common alignment_offset */
564 t->alignment_offset = lcm_not_zero(t->alignment_offset, alignment)
565 % max(t->physical_block_size, t->io_min);
566
567 /* Verify that new alignment_offset is on a logical block boundary */
568 if (t->alignment_offset & (t->logical_block_size - 1)) {
569 t->misaligned = 1;
570 ret = -1;
571 }
572
573 /* Discard alignment and granularity */
574 if (b->discard_granularity) {
575 alignment = queue_limit_discard_alignment(b, start);
576
577 if (t->discard_granularity != 0 &&
578 t->discard_alignment != alignment) {
579 top = t->discard_granularity + t->discard_alignment;
580 bottom = b->discard_granularity + alignment;
581
582 /* Verify that top and bottom intervals line up */
583 if ((max(top, bottom) % min(top, bottom)) != 0)
584 t->discard_misaligned = 1;
585 }
586
587 t->max_discard_sectors = min_not_zero(t->max_discard_sectors,
588 b->max_discard_sectors);
589 t->max_hw_discard_sectors = min_not_zero(t->max_hw_discard_sectors,
590 b->max_hw_discard_sectors);
591 t->discard_granularity = max(t->discard_granularity,
592 b->discard_granularity);
593 t->discard_alignment = lcm_not_zero(t->discard_alignment, alignment) %
594 t->discard_granularity;
595 }
596
597 if (b->chunk_sectors)
598 t->chunk_sectors = min_not_zero(t->chunk_sectors,
599 b->chunk_sectors);
600
601 t->zoned = max(t->zoned, b->zoned);
602 return ret;
603}
604EXPORT_SYMBOL(blk_stack_limits);
605
606/**
607 * disk_stack_limits - adjust queue limits for stacked drivers
608 * @disk: MD/DM gendisk (top)
609 * @bdev: the underlying block device (bottom)
610 * @offset: offset to beginning of data within component device
611 *
612 * Description:
613 * Merges the limits for a top level gendisk and a bottom level
614 * block_device.
615 */
616void disk_stack_limits(struct gendisk *disk, struct block_device *bdev,
617 sector_t offset)
618{
619 struct request_queue *t = disk->queue;
620
621 if (blk_stack_limits(&t->limits, &bdev_get_queue(bdev)->limits,
622 get_start_sect(bdev) + (offset >> 9)) < 0) {
623 char top[BDEVNAME_SIZE], bottom[BDEVNAME_SIZE];
624
625 disk_name(disk, 0, top);
626 bdevname(bdev, bottom);
627
628 printk(KERN_NOTICE "%s: Warning: Device %s is misaligned\n",
629 top, bottom);
630 }
631
632 t->backing_dev_info->io_pages =
633 t->limits.max_sectors >> (PAGE_SHIFT - 9);
634}
635EXPORT_SYMBOL(disk_stack_limits);
636
637/**
638 * blk_queue_update_dma_pad - update pad mask
639 * @q: the request queue for the device
640 * @mask: pad mask
641 *
642 * Update dma pad mask.
643 *
644 * Appending pad buffer to a request modifies the last entry of a
645 * scatter list such that it includes the pad buffer.
646 **/
647void blk_queue_update_dma_pad(struct request_queue *q, unsigned int mask)
648{
649 if (mask > q->dma_pad_mask)
650 q->dma_pad_mask = mask;
651}
652EXPORT_SYMBOL(blk_queue_update_dma_pad);
653
654/**
655 * blk_queue_segment_boundary - set boundary rules for segment merging
656 * @q: the request queue for the device
657 * @mask: the memory boundary mask
658 **/
659void blk_queue_segment_boundary(struct request_queue *q, unsigned long mask)
660{
661 if (mask < PAGE_SIZE - 1) {
662 mask = PAGE_SIZE - 1;
663 printk(KERN_INFO "%s: set to minimum %lx\n",
664 __func__, mask);
665 }
666
667 q->limits.seg_boundary_mask = mask;
668}
669EXPORT_SYMBOL(blk_queue_segment_boundary);
670
671/**
672 * blk_queue_virt_boundary - set boundary rules for bio merging
673 * @q: the request queue for the device
674 * @mask: the memory boundary mask
675 **/
676void blk_queue_virt_boundary(struct request_queue *q, unsigned long mask)
677{
678 q->limits.virt_boundary_mask = mask;
679
680 /*
681 * Devices that require a virtual boundary do not support scatter/gather
682 * I/O natively, but instead require a descriptor list entry for each
683 * page (which might not be idential to the Linux PAGE_SIZE). Because
684 * of that they are not limited by our notion of "segment size".
685 */
686 if (mask)
687 q->limits.max_segment_size = UINT_MAX;
688}
689EXPORT_SYMBOL(blk_queue_virt_boundary);
690
691/**
692 * blk_queue_dma_alignment - set dma length and memory alignment
693 * @q: the request queue for the device
694 * @mask: alignment mask
695 *
696 * description:
697 * set required memory and length alignment for direct dma transactions.
698 * this is used when building direct io requests for the queue.
699 *
700 **/
701void blk_queue_dma_alignment(struct request_queue *q, int mask)
702{
703 q->dma_alignment = mask;
704}
705EXPORT_SYMBOL(blk_queue_dma_alignment);
706
707/**
708 * blk_queue_update_dma_alignment - update dma length and memory alignment
709 * @q: the request queue for the device
710 * @mask: alignment mask
711 *
712 * description:
713 * update required memory and length alignment for direct dma transactions.
714 * If the requested alignment is larger than the current alignment, then
715 * the current queue alignment is updated to the new value, otherwise it
716 * is left alone. The design of this is to allow multiple objects
717 * (driver, device, transport etc) to set their respective
718 * alignments without having them interfere.
719 *
720 **/
721void blk_queue_update_dma_alignment(struct request_queue *q, int mask)
722{
723 BUG_ON(mask > PAGE_SIZE);
724
725 if (mask > q->dma_alignment)
726 q->dma_alignment = mask;
727}
728EXPORT_SYMBOL(blk_queue_update_dma_alignment);
729
730/**
731 * blk_set_queue_depth - tell the block layer about the device queue depth
732 * @q: the request queue for the device
733 * @depth: queue depth
734 *
735 */
736void blk_set_queue_depth(struct request_queue *q, unsigned int depth)
737{
738 q->queue_depth = depth;
739 rq_qos_queue_depth_changed(q);
740}
741EXPORT_SYMBOL(blk_set_queue_depth);
742
743/**
744 * blk_queue_write_cache - configure queue's write cache
745 * @q: the request queue for the device
746 * @wc: write back cache on or off
747 * @fua: device supports FUA writes, if true
748 *
749 * Tell the block layer about the write cache of @q.
750 */
751void blk_queue_write_cache(struct request_queue *q, bool wc, bool fua)
752{
753 if (wc)
754 blk_queue_flag_set(QUEUE_FLAG_WC, q);
755 else
756 blk_queue_flag_clear(QUEUE_FLAG_WC, q);
757 if (fua)
758 blk_queue_flag_set(QUEUE_FLAG_FUA, q);
759 else
760 blk_queue_flag_clear(QUEUE_FLAG_FUA, q);
761
762 wbt_set_write_cache(q, test_bit(QUEUE_FLAG_WC, &q->queue_flags));
763}
764EXPORT_SYMBOL_GPL(blk_queue_write_cache);
765
766/**
767 * blk_queue_required_elevator_features - Set a queue required elevator features
768 * @q: the request queue for the target device
769 * @features: Required elevator features OR'ed together
770 *
771 * Tell the block layer that for the device controlled through @q, only the
772 * only elevators that can be used are those that implement at least the set of
773 * features specified by @features.
774 */
775void blk_queue_required_elevator_features(struct request_queue *q,
776 unsigned int features)
777{
778 q->required_elevator_features = features;
779}
780EXPORT_SYMBOL_GPL(blk_queue_required_elevator_features);
781
782/**
783 * blk_queue_can_use_dma_map_merging - configure queue for merging segments.
784 * @q: the request queue for the device
785 * @dev: the device pointer for dma
786 *
787 * Tell the block layer about merging the segments by dma map of @q.
788 */
789bool blk_queue_can_use_dma_map_merging(struct request_queue *q,
790 struct device *dev)
791{
792 unsigned long boundary = dma_get_merge_boundary(dev);
793
794 if (!boundary)
795 return false;
796
797 /* No need to update max_segment_size. see blk_queue_virt_boundary() */
798 blk_queue_virt_boundary(q, boundary);
799
800 return true;
801}
802EXPORT_SYMBOL_GPL(blk_queue_can_use_dma_map_merging);
803
804/**
805 * blk_queue_set_zoned - configure a disk queue zoned model.
806 * @disk: the gendisk of the queue to configure
807 * @model: the zoned model to set
808 *
809 * Set the zoned model of the request queue of @disk according to @model.
810 * When @model is BLK_ZONED_HM (host managed), this should be called only
811 * if zoned block device support is enabled (CONFIG_BLK_DEV_ZONED option).
812 * If @model specifies BLK_ZONED_HA (host aware), the effective model used
813 * depends on CONFIG_BLK_DEV_ZONED settings and on the existence of partitions
814 * on the disk.
815 */
816void blk_queue_set_zoned(struct gendisk *disk, enum blk_zoned_model model)
817{
818 switch (model) {
819 case BLK_ZONED_HM:
820 /*
821 * Host managed devices are supported only if
822 * CONFIG_BLK_DEV_ZONED is enabled.
823 */
824 WARN_ON_ONCE(!IS_ENABLED(CONFIG_BLK_DEV_ZONED));
825 break;
826 case BLK_ZONED_HA:
827 /*
828 * Host aware devices can be treated either as regular block
829 * devices (similar to drive managed devices) or as zoned block
830 * devices to take advantage of the zone command set, similarly
831 * to host managed devices. We try the latter if there are no
832 * partitions and zoned block device support is enabled, else
833 * we do nothing special as far as the block layer is concerned.
834 */
835 if (!IS_ENABLED(CONFIG_BLK_DEV_ZONED) ||
836 disk_has_partitions(disk))
837 model = BLK_ZONED_NONE;
838 break;
839 case BLK_ZONED_NONE:
840 default:
841 if (WARN_ON_ONCE(model != BLK_ZONED_NONE))
842 model = BLK_ZONED_NONE;
843 break;
844 }
845
846 disk->queue->limits.zoned = model;
847}
848EXPORT_SYMBOL_GPL(blk_queue_set_zoned);
849
850static int __init blk_settings_init(void)
851{
852 blk_max_low_pfn = max_low_pfn - 1;
853 blk_max_pfn = max_pfn - 1;
854 return 0;
855}
856subsys_initcall(blk_settings_init);