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path: root/block/blk-settings.c (plain)
blob: 65f16cf4f8509b094585e119e7bcc47a5ae45b64
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 q->backing_dev_info.io_pages = max_sectors >> (PAGE_SHIFT - 9);
253}
254EXPORT_SYMBOL(blk_queue_max_hw_sectors);
255
256/**
257 * blk_queue_chunk_sectors - set size of the chunk for this queue
258 * @q: the request queue for the device
259 * @chunk_sectors: chunk sectors in the usual 512b unit
260 *
261 * Description:
262 * If a driver doesn't want IOs to cross a given chunk size, it can set
263 * this limit and prevent merging across chunks. Note that the chunk size
264 * must currently be a power-of-2 in sectors. Also note that the block
265 * layer must accept a page worth of data at any offset. So if the
266 * crossing of chunks is a hard limitation in the driver, it must still be
267 * prepared to split single page bios.
268 **/
269void blk_queue_chunk_sectors(struct request_queue *q, unsigned int chunk_sectors)
270{
271 BUG_ON(!is_power_of_2(chunk_sectors));
272 q->limits.chunk_sectors = chunk_sectors;
273}
274EXPORT_SYMBOL(blk_queue_chunk_sectors);
275
276/**
277 * blk_queue_max_discard_sectors - set max sectors for a single discard
278 * @q: the request queue for the device
279 * @max_discard_sectors: maximum number of sectors to discard
280 **/
281void blk_queue_max_discard_sectors(struct request_queue *q,
282 unsigned int max_discard_sectors)
283{
284 q->limits.max_hw_discard_sectors = max_discard_sectors;
285 q->limits.max_discard_sectors = max_discard_sectors;
286}
287EXPORT_SYMBOL(blk_queue_max_discard_sectors);
288
289/**
290 * blk_queue_max_write_same_sectors - set max sectors for a single write same
291 * @q: the request queue for the device
292 * @max_write_same_sectors: maximum number of sectors to write per command
293 **/
294void blk_queue_max_write_same_sectors(struct request_queue *q,
295 unsigned int max_write_same_sectors)
296{
297 q->limits.max_write_same_sectors = max_write_same_sectors;
298}
299EXPORT_SYMBOL(blk_queue_max_write_same_sectors);
300
301/**
302 * blk_queue_max_segments - set max hw segments for a request for this queue
303 * @q: the request queue for the device
304 * @max_segments: max number of segments
305 *
306 * Description:
307 * Enables a low level driver to set an upper limit on the number of
308 * hw data segments in a request.
309 **/
310void blk_queue_max_segments(struct request_queue *q, unsigned short max_segments)
311{
312 if (!max_segments) {
313 max_segments = 1;
314 printk(KERN_INFO "%s: set to minimum %d\n",
315 __func__, max_segments);
316 }
317
318 q->limits.max_segments = max_segments;
319}
320EXPORT_SYMBOL(blk_queue_max_segments);
321
322/**
323 * blk_queue_max_segment_size - set max segment size for blk_rq_map_sg
324 * @q: the request queue for the device
325 * @max_size: max size of segment in bytes
326 *
327 * Description:
328 * Enables a low level driver to set an upper limit on the size of a
329 * coalesced segment
330 **/
331void blk_queue_max_segment_size(struct request_queue *q, unsigned int max_size)
332{
333 if (max_size < PAGE_SIZE) {
334 max_size = PAGE_SIZE;
335 printk(KERN_INFO "%s: set to minimum %d\n",
336 __func__, max_size);
337 }
338
339 q->limits.max_segment_size = max_size;
340}
341EXPORT_SYMBOL(blk_queue_max_segment_size);
342
343/**
344 * blk_queue_logical_block_size - set logical block size for the queue
345 * @q: the request queue for the device
346 * @size: the logical block size, in bytes
347 *
348 * Description:
349 * This should be set to the lowest possible block size that the
350 * storage device can address. The default of 512 covers most
351 * hardware.
352 **/
353void blk_queue_logical_block_size(struct request_queue *q, unsigned short size)
354{
355 q->limits.logical_block_size = size;
356
357 if (q->limits.physical_block_size < size)
358 q->limits.physical_block_size = size;
359
360 if (q->limits.io_min < q->limits.physical_block_size)
361 q->limits.io_min = q->limits.physical_block_size;
362}
363EXPORT_SYMBOL(blk_queue_logical_block_size);
364
365/**
366 * blk_queue_physical_block_size - set physical block size for the queue
367 * @q: the request queue for the device
368 * @size: the physical block size, in bytes
369 *
370 * Description:
371 * This should be set to the lowest possible sector size that the
372 * hardware can operate on without reverting to read-modify-write
373 * operations.
374 */
375void blk_queue_physical_block_size(struct request_queue *q, unsigned int size)
376{
377 q->limits.physical_block_size = size;
378
379 if (q->limits.physical_block_size < q->limits.logical_block_size)
380 q->limits.physical_block_size = q->limits.logical_block_size;
381
382 if (q->limits.io_min < q->limits.physical_block_size)
383 q->limits.io_min = q->limits.physical_block_size;
384}
385EXPORT_SYMBOL(blk_queue_physical_block_size);
386
387/**
388 * blk_queue_alignment_offset - set physical block alignment offset
389 * @q: the request queue for the device
390 * @offset: alignment offset in bytes
391 *
392 * Description:
393 * Some devices are naturally misaligned to compensate for things like
394 * the legacy DOS partition table 63-sector offset. Low-level drivers
395 * should call this function for devices whose first sector is not
396 * naturally aligned.
397 */
398void blk_queue_alignment_offset(struct request_queue *q, unsigned int offset)
399{
400 q->limits.alignment_offset =
401 offset & (q->limits.physical_block_size - 1);
402 q->limits.misaligned = 0;
403}
404EXPORT_SYMBOL(blk_queue_alignment_offset);
405
406/**
407 * blk_limits_io_min - set minimum request size for a device
408 * @limits: the queue limits
409 * @min: smallest I/O size in bytes
410 *
411 * Description:
412 * Some devices have an internal block size bigger than the reported
413 * hardware sector size. This function can be used to signal the
414 * smallest I/O the device can perform without incurring a performance
415 * penalty.
416 */
417void blk_limits_io_min(struct queue_limits *limits, unsigned int min)
418{
419 limits->io_min = min;
420
421 if (limits->io_min < limits->logical_block_size)
422 limits->io_min = limits->logical_block_size;
423
424 if (limits->io_min < limits->physical_block_size)
425 limits->io_min = limits->physical_block_size;
426}
427EXPORT_SYMBOL(blk_limits_io_min);
428
429/**
430 * blk_queue_io_min - set minimum request size for the queue
431 * @q: the request queue for the device
432 * @min: smallest I/O size in bytes
433 *
434 * Description:
435 * Storage devices may report a granularity or preferred minimum I/O
436 * size which is the smallest request the device can perform without
437 * incurring a performance penalty. For disk drives this is often the
438 * physical block size. For RAID arrays it is often the stripe chunk
439 * size. A properly aligned multiple of minimum_io_size is the
440 * preferred request size for workloads where a high number of I/O
441 * operations is desired.
442 */
443void blk_queue_io_min(struct request_queue *q, unsigned int min)
444{
445 blk_limits_io_min(&q->limits, min);
446}
447EXPORT_SYMBOL(blk_queue_io_min);
448
449/**
450 * blk_limits_io_opt - set optimal request size for a device
451 * @limits: the queue limits
452 * @opt: smallest I/O size in bytes
453 *
454 * Description:
455 * Storage devices may report an optimal I/O size, which is the
456 * device's preferred unit for sustained I/O. This is rarely reported
457 * for disk drives. For RAID arrays it is usually the stripe width or
458 * the internal track size. A properly aligned multiple of
459 * optimal_io_size is the preferred request size for workloads where
460 * sustained throughput is desired.
461 */
462void blk_limits_io_opt(struct queue_limits *limits, unsigned int opt)
463{
464 limits->io_opt = opt;
465}
466EXPORT_SYMBOL(blk_limits_io_opt);
467
468/**
469 * blk_queue_io_opt - set optimal request size for the queue
470 * @q: the request queue for the device
471 * @opt: optimal request size in bytes
472 *
473 * Description:
474 * Storage devices may report an optimal I/O size, which is the
475 * device's preferred unit for sustained I/O. This is rarely reported
476 * for disk drives. For RAID arrays it is usually the stripe width or
477 * the internal track size. A properly aligned multiple of
478 * optimal_io_size is the preferred request size for workloads where
479 * sustained throughput is desired.
480 */
481void blk_queue_io_opt(struct request_queue *q, unsigned int opt)
482{
483 blk_limits_io_opt(&q->limits, opt);
484}
485EXPORT_SYMBOL(blk_queue_io_opt);
486
487/**
488 * blk_queue_stack_limits - inherit underlying queue limits for stacked drivers
489 * @t: the stacking driver (top)
490 * @b: the underlying device (bottom)
491 **/
492void blk_queue_stack_limits(struct request_queue *t, struct request_queue *b)
493{
494 blk_stack_limits(&t->limits, &b->limits, 0);
495}
496EXPORT_SYMBOL(blk_queue_stack_limits);
497
498/**
499 * blk_stack_limits - adjust queue_limits for stacked devices
500 * @t: the stacking driver limits (top device)
501 * @b: the underlying queue limits (bottom, component device)
502 * @start: first data sector within component device
503 *
504 * Description:
505 * This function is used by stacking drivers like MD and DM to ensure
506 * that all component devices have compatible block sizes and
507 * alignments. The stacking driver must provide a queue_limits
508 * struct (top) and then iteratively call the stacking function for
509 * all component (bottom) devices. The stacking function will
510 * attempt to combine the values and ensure proper alignment.
511 *
512 * Returns 0 if the top and bottom queue_limits are compatible. The
513 * top device's block sizes and alignment offsets may be adjusted to
514 * ensure alignment with the bottom device. If no compatible sizes
515 * and alignments exist, -1 is returned and the resulting top
516 * queue_limits will have the misaligned flag set to indicate that
517 * the alignment_offset is undefined.
518 */
519int blk_stack_limits(struct queue_limits *t, struct queue_limits *b,
520 sector_t start)
521{
522 unsigned int top, bottom, alignment, ret = 0;
523
524 t->max_sectors = min_not_zero(t->max_sectors, b->max_sectors);
525 t->max_hw_sectors = min_not_zero(t->max_hw_sectors, b->max_hw_sectors);
526 t->max_dev_sectors = min_not_zero(t->max_dev_sectors, b->max_dev_sectors);
527 t->max_write_same_sectors = min(t->max_write_same_sectors,
528 b->max_write_same_sectors);
529 t->bounce_pfn = min_not_zero(t->bounce_pfn, b->bounce_pfn);
530
531 t->seg_boundary_mask = min_not_zero(t->seg_boundary_mask,
532 b->seg_boundary_mask);
533 t->virt_boundary_mask = min_not_zero(t->virt_boundary_mask,
534 b->virt_boundary_mask);
535
536 t->max_segments = min_not_zero(t->max_segments, b->max_segments);
537 t->max_integrity_segments = min_not_zero(t->max_integrity_segments,
538 b->max_integrity_segments);
539
540 t->max_segment_size = min_not_zero(t->max_segment_size,
541 b->max_segment_size);
542
543 t->misaligned |= b->misaligned;
544
545 alignment = queue_limit_alignment_offset(b, start);
546
547 /* Bottom device has different alignment. Check that it is
548 * compatible with the current top alignment.
549 */
550 if (t->alignment_offset != alignment) {
551
552 top = max(t->physical_block_size, t->io_min)
553 + t->alignment_offset;
554 bottom = max(b->physical_block_size, b->io_min) + alignment;
555
556 /* Verify that top and bottom intervals line up */
557 if (max(top, bottom) % min(top, bottom)) {
558 t->misaligned = 1;
559 ret = -1;
560 }
561 }
562
563 t->logical_block_size = max(t->logical_block_size,
564 b->logical_block_size);
565
566 t->physical_block_size = max(t->physical_block_size,
567 b->physical_block_size);
568
569 t->io_min = max(t->io_min, b->io_min);
570 t->io_opt = lcm_not_zero(t->io_opt, b->io_opt);
571
572 t->cluster &= b->cluster;
573 t->discard_zeroes_data &= b->discard_zeroes_data;
574
575 /* Physical block size a multiple of the logical block size? */
576 if (t->physical_block_size & (t->logical_block_size - 1)) {
577 t->physical_block_size = t->logical_block_size;
578 t->misaligned = 1;
579 ret = -1;
580 }
581
582 /* Minimum I/O a multiple of the physical block size? */
583 if (t->io_min & (t->physical_block_size - 1)) {
584 t->io_min = t->physical_block_size;
585 t->misaligned = 1;
586 ret = -1;
587 }
588
589 /* Optimal I/O a multiple of the physical block size? */
590 if (t->io_opt & (t->physical_block_size - 1)) {
591 t->io_opt = 0;
592 t->misaligned = 1;
593 ret = -1;
594 }
595
596 t->raid_partial_stripes_expensive =
597 max(t->raid_partial_stripes_expensive,
598 b->raid_partial_stripes_expensive);
599
600 /* Find lowest common alignment_offset */
601 t->alignment_offset = lcm_not_zero(t->alignment_offset, alignment)
602 % max(t->physical_block_size, t->io_min);
603
604 /* Verify that new alignment_offset is on a logical block boundary */
605 if (t->alignment_offset & (t->logical_block_size - 1)) {
606 t->misaligned = 1;
607 ret = -1;
608 }
609
610 /* Discard alignment and granularity */
611 if (b->discard_granularity) {
612 alignment = queue_limit_discard_alignment(b, start);
613
614 if (t->discard_granularity != 0 &&
615 t->discard_alignment != alignment) {
616 top = t->discard_granularity + t->discard_alignment;
617 bottom = b->discard_granularity + alignment;
618
619 /* Verify that top and bottom intervals line up */
620 if ((max(top, bottom) % min(top, bottom)) != 0)
621 t->discard_misaligned = 1;
622 }
623
624 t->max_discard_sectors = min_not_zero(t->max_discard_sectors,
625 b->max_discard_sectors);
626 t->max_hw_discard_sectors = min_not_zero(t->max_hw_discard_sectors,
627 b->max_hw_discard_sectors);
628 t->discard_granularity = max(t->discard_granularity,
629 b->discard_granularity);
630 t->discard_alignment = lcm_not_zero(t->discard_alignment, alignment) %
631 t->discard_granularity;
632 }
633
634 return ret;
635}
636EXPORT_SYMBOL(blk_stack_limits);
637
638/**
639 * bdev_stack_limits - adjust queue limits for stacked drivers
640 * @t: the stacking driver limits (top device)
641 * @bdev: the component block_device (bottom)
642 * @start: first data sector within component device
643 *
644 * Description:
645 * Merges queue limits for a top device and a block_device. Returns
646 * 0 if alignment didn't change. Returns -1 if adding the bottom
647 * device caused misalignment.
648 */
649int bdev_stack_limits(struct queue_limits *t, struct block_device *bdev,
650 sector_t start)
651{
652 struct request_queue *bq = bdev_get_queue(bdev);
653
654 start += get_start_sect(bdev);
655
656 return blk_stack_limits(t, &bq->limits, start);
657}
658EXPORT_SYMBOL(bdev_stack_limits);
659
660/**
661 * disk_stack_limits - adjust queue limits for stacked drivers
662 * @disk: MD/DM gendisk (top)
663 * @bdev: the underlying block device (bottom)
664 * @offset: offset to beginning of data within component device
665 *
666 * Description:
667 * Merges the limits for a top level gendisk and a bottom level
668 * block_device.
669 */
670void disk_stack_limits(struct gendisk *disk, struct block_device *bdev,
671 sector_t offset)
672{
673 struct request_queue *t = disk->queue;
674
675 if (bdev_stack_limits(&t->limits, bdev, offset >> 9) < 0) {
676 char top[BDEVNAME_SIZE], bottom[BDEVNAME_SIZE];
677
678 disk_name(disk, 0, top);
679 bdevname(bdev, bottom);
680
681 printk(KERN_NOTICE "%s: Warning: Device %s is misaligned\n",
682 top, bottom);
683 }
684}
685EXPORT_SYMBOL(disk_stack_limits);
686
687/**
688 * blk_queue_dma_pad - set pad mask
689 * @q: the request queue for the device
690 * @mask: pad mask
691 *
692 * Set dma pad mask.
693 *
694 * Appending pad buffer to a request modifies the last entry of a
695 * scatter list such that it includes the pad buffer.
696 **/
697void blk_queue_dma_pad(struct request_queue *q, unsigned int mask)
698{
699 q->dma_pad_mask = mask;
700}
701EXPORT_SYMBOL(blk_queue_dma_pad);
702
703/**
704 * blk_queue_update_dma_pad - update pad mask
705 * @q: the request queue for the device
706 * @mask: pad mask
707 *
708 * Update dma pad mask.
709 *
710 * Appending pad buffer to a request modifies the last entry of a
711 * scatter list such that it includes the pad buffer.
712 **/
713void blk_queue_update_dma_pad(struct request_queue *q, unsigned int mask)
714{
715 if (mask > q->dma_pad_mask)
716 q->dma_pad_mask = mask;
717}
718EXPORT_SYMBOL(blk_queue_update_dma_pad);
719
720/**
721 * blk_queue_dma_drain - Set up a drain buffer for excess dma.
722 * @q: the request queue for the device
723 * @dma_drain_needed: fn which returns non-zero if drain is necessary
724 * @buf: physically contiguous buffer
725 * @size: size of the buffer in bytes
726 *
727 * Some devices have excess DMA problems and can't simply discard (or
728 * zero fill) the unwanted piece of the transfer. They have to have a
729 * real area of memory to transfer it into. The use case for this is
730 * ATAPI devices in DMA mode. If the packet command causes a transfer
731 * bigger than the transfer size some HBAs will lock up if there
732 * aren't DMA elements to contain the excess transfer. What this API
733 * does is adjust the queue so that the buf is always appended
734 * silently to the scatterlist.
735 *
736 * Note: This routine adjusts max_hw_segments to make room for appending
737 * the drain buffer. If you call blk_queue_max_segments() after calling
738 * this routine, you must set the limit to one fewer than your device
739 * can support otherwise there won't be room for the drain buffer.
740 */
741int blk_queue_dma_drain(struct request_queue *q,
742 dma_drain_needed_fn *dma_drain_needed,
743 void *buf, unsigned int size)
744{
745 if (queue_max_segments(q) < 2)
746 return -EINVAL;
747 /* make room for appending the drain */
748 blk_queue_max_segments(q, queue_max_segments(q) - 1);
749 q->dma_drain_needed = dma_drain_needed;
750 q->dma_drain_buffer = buf;
751 q->dma_drain_size = size;
752
753 return 0;
754}
755EXPORT_SYMBOL_GPL(blk_queue_dma_drain);
756
757/**
758 * blk_queue_segment_boundary - set boundary rules for segment merging
759 * @q: the request queue for the device
760 * @mask: the memory boundary mask
761 **/
762void blk_queue_segment_boundary(struct request_queue *q, unsigned long mask)
763{
764 if (mask < PAGE_SIZE - 1) {
765 mask = PAGE_SIZE - 1;
766 printk(KERN_INFO "%s: set to minimum %lx\n",
767 __func__, mask);
768 }
769
770 q->limits.seg_boundary_mask = mask;
771}
772EXPORT_SYMBOL(blk_queue_segment_boundary);
773
774/**
775 * blk_queue_virt_boundary - set boundary rules for bio merging
776 * @q: the request queue for the device
777 * @mask: the memory boundary mask
778 **/
779void blk_queue_virt_boundary(struct request_queue *q, unsigned long mask)
780{
781 q->limits.virt_boundary_mask = mask;
782}
783EXPORT_SYMBOL(blk_queue_virt_boundary);
784
785/**
786 * blk_queue_dma_alignment - set dma length and memory alignment
787 * @q: the request queue for the device
788 * @mask: alignment mask
789 *
790 * description:
791 * set required memory and length alignment for direct dma transactions.
792 * this is used when building direct io requests for the queue.
793 *
794 **/
795void blk_queue_dma_alignment(struct request_queue *q, int mask)
796{
797 q->dma_alignment = mask;
798}
799EXPORT_SYMBOL(blk_queue_dma_alignment);
800
801/**
802 * blk_queue_update_dma_alignment - update dma length and memory alignment
803 * @q: the request queue for the device
804 * @mask: alignment mask
805 *
806 * description:
807 * update required memory and length alignment for direct dma transactions.
808 * If the requested alignment is larger than the current alignment, then
809 * the current queue alignment is updated to the new value, otherwise it
810 * is left alone. The design of this is to allow multiple objects
811 * (driver, device, transport etc) to set their respective
812 * alignments without having them interfere.
813 *
814 **/
815void blk_queue_update_dma_alignment(struct request_queue *q, int mask)
816{
817 BUG_ON(mask > PAGE_SIZE);
818
819 if (mask > q->dma_alignment)
820 q->dma_alignment = mask;
821}
822EXPORT_SYMBOL(blk_queue_update_dma_alignment);
823
824void blk_queue_flush_queueable(struct request_queue *q, bool queueable)
825{
826 spin_lock_irq(q->queue_lock);
827 if (queueable)
828 clear_bit(QUEUE_FLAG_FLUSH_NQ, &q->queue_flags);
829 else
830 set_bit(QUEUE_FLAG_FLUSH_NQ, &q->queue_flags);
831 spin_unlock_irq(q->queue_lock);
832}
833EXPORT_SYMBOL_GPL(blk_queue_flush_queueable);
834
835/**
836 * blk_queue_write_cache - configure queue's write cache
837 * @q: the request queue for the device
838 * @wc: write back cache on or off
839 * @fua: device supports FUA writes, if true
840 *
841 * Tell the block layer about the write cache of @q.
842 */
843void blk_queue_write_cache(struct request_queue *q, bool wc, bool fua)
844{
845 spin_lock_irq(q->queue_lock);
846 if (wc)
847 queue_flag_set(QUEUE_FLAG_WC, q);
848 else
849 queue_flag_clear(QUEUE_FLAG_WC, q);
850 if (fua)
851 queue_flag_set(QUEUE_FLAG_FUA, q);
852 else
853 queue_flag_clear(QUEUE_FLAG_FUA, q);
854 spin_unlock_irq(q->queue_lock);
855}
856EXPORT_SYMBOL_GPL(blk_queue_write_cache);
857
858static int __init blk_settings_init(void)
859{
860 blk_max_low_pfn = max_low_pfn - 1;
861 blk_max_pfn = max_pfn - 1;
862 return 0;
863}
864subsys_initcall(blk_settings_init);
865
generated by cgit at 2024-05-18 15:48:31 (GMT)