ALSA: hda - Remove ALC268 Dell, Toshiba and Zapto model quirks
[linux-2.6/linux-acpi-2.6/ibm-acpi-2.6.git] / block / blk-settings.c
blobfa1eb0449a05f0db45de3ab8e6a01a2fc2a95238
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>
15 #include "blk.h"
17 unsigned long blk_max_low_pfn;
18 EXPORT_SYMBOL(blk_max_low_pfn);
20 unsigned long blk_max_pfn;
22 /**
23 * blk_queue_prep_rq - set a prepare_request function for queue
24 * @q: queue
25 * @pfn: prepare_request function
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.
33 void blk_queue_prep_rq(struct request_queue *q, prep_rq_fn *pfn)
35 q->prep_rq_fn = pfn;
37 EXPORT_SYMBOL(blk_queue_prep_rq);
39 /**
40 * blk_queue_unprep_rq - set an unprepare_request function for queue
41 * @q: queue
42 * @ufn: unprepare_request function
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.
50 void blk_queue_unprep_rq(struct request_queue *q, unprep_rq_fn *ufn)
52 q->unprep_rq_fn = ufn;
54 EXPORT_SYMBOL(blk_queue_unprep_rq);
56 /**
57 * blk_queue_merge_bvec - set a merge_bvec function for queue
58 * @q: queue
59 * @mbfn: merge_bvec_fn
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.
72 void blk_queue_merge_bvec(struct request_queue *q, merge_bvec_fn *mbfn)
74 q->merge_bvec_fn = mbfn;
76 EXPORT_SYMBOL(blk_queue_merge_bvec);
78 void blk_queue_softirq_done(struct request_queue *q, softirq_done_fn *fn)
80 q->softirq_done_fn = fn;
82 EXPORT_SYMBOL(blk_queue_softirq_done);
84 void blk_queue_rq_timeout(struct request_queue *q, unsigned int timeout)
86 q->rq_timeout = timeout;
88 EXPORT_SYMBOL_GPL(blk_queue_rq_timeout);
90 void blk_queue_rq_timed_out(struct request_queue *q, rq_timed_out_fn *fn)
92 q->rq_timed_out_fn = fn;
94 EXPORT_SYMBOL_GPL(blk_queue_rq_timed_out);
96 void blk_queue_lld_busy(struct request_queue *q, lld_busy_fn *fn)
98 q->lld_busy_fn = fn;
100 EXPORT_SYMBOL_GPL(blk_queue_lld_busy);
103 * blk_set_default_limits - reset limits to default values
104 * @lim: the queue_limits structure to reset
106 * Description:
107 * Returns a queue_limit struct to its default state. Can be used by
108 * stacking drivers like DM that stage table swaps and reuse an
109 * existing device queue.
111 void blk_set_default_limits(struct queue_limits *lim)
113 lim->max_segments = BLK_MAX_SEGMENTS;
114 lim->max_integrity_segments = 0;
115 lim->seg_boundary_mask = BLK_SEG_BOUNDARY_MASK;
116 lim->max_segment_size = BLK_MAX_SEGMENT_SIZE;
117 lim->max_sectors = BLK_DEF_MAX_SECTORS;
118 lim->max_hw_sectors = INT_MAX;
119 lim->max_discard_sectors = 0;
120 lim->discard_granularity = 0;
121 lim->discard_alignment = 0;
122 lim->discard_misaligned = 0;
123 lim->discard_zeroes_data = 1;
124 lim->logical_block_size = lim->physical_block_size = lim->io_min = 512;
125 lim->bounce_pfn = (unsigned long)(BLK_BOUNCE_ANY >> PAGE_SHIFT);
126 lim->alignment_offset = 0;
127 lim->io_opt = 0;
128 lim->misaligned = 0;
129 lim->cluster = 1;
131 EXPORT_SYMBOL(blk_set_default_limits);
134 * blk_queue_make_request - define an alternate make_request function for a device
135 * @q: the request queue for the device to be affected
136 * @mfn: the alternate make_request function
138 * Description:
139 * The normal way for &struct bios to be passed to a device
140 * driver is for them to be collected into requests on a request
141 * queue, and then to allow the device driver to select requests
142 * off that queue when it is ready. This works well for many block
143 * devices. However some block devices (typically virtual devices
144 * such as md or lvm) do not benefit from the processing on the
145 * request queue, and are served best by having the requests passed
146 * directly to them. This can be achieved by providing a function
147 * to blk_queue_make_request().
149 * Caveat:
150 * The driver that does this *must* be able to deal appropriately
151 * with buffers in "highmemory". This can be accomplished by either calling
152 * __bio_kmap_atomic() to get a temporary kernel mapping, or by calling
153 * blk_queue_bounce() to create a buffer in normal memory.
155 void blk_queue_make_request(struct request_queue *q, make_request_fn *mfn)
158 * set defaults
160 q->nr_requests = BLKDEV_MAX_RQ;
162 q->make_request_fn = mfn;
163 blk_queue_dma_alignment(q, 511);
164 blk_queue_congestion_threshold(q);
165 q->nr_batching = BLK_BATCH_REQ;
167 blk_set_default_limits(&q->limits);
168 blk_queue_max_hw_sectors(q, BLK_SAFE_MAX_SECTORS);
169 q->limits.discard_zeroes_data = 0;
172 * by default assume old behaviour and bounce for any highmem page
174 blk_queue_bounce_limit(q, BLK_BOUNCE_HIGH);
176 EXPORT_SYMBOL(blk_queue_make_request);
179 * blk_queue_bounce_limit - set bounce buffer limit for queue
180 * @q: the request queue for the device
181 * @dma_mask: the maximum address the device can handle
183 * Description:
184 * Different hardware can have different requirements as to what pages
185 * it can do I/O directly to. A low level driver can call
186 * blk_queue_bounce_limit to have lower memory pages allocated as bounce
187 * buffers for doing I/O to pages residing above @dma_mask.
189 void blk_queue_bounce_limit(struct request_queue *q, u64 dma_mask)
191 unsigned long b_pfn = dma_mask >> PAGE_SHIFT;
192 int dma = 0;
194 q->bounce_gfp = GFP_NOIO;
195 #if BITS_PER_LONG == 64
197 * Assume anything <= 4GB can be handled by IOMMU. Actually
198 * some IOMMUs can handle everything, but I don't know of a
199 * way to test this here.
201 if (b_pfn < (min_t(u64, 0xffffffffUL, BLK_BOUNCE_HIGH) >> PAGE_SHIFT))
202 dma = 1;
203 q->limits.bounce_pfn = max(max_low_pfn, b_pfn);
204 #else
205 if (b_pfn < blk_max_low_pfn)
206 dma = 1;
207 q->limits.bounce_pfn = b_pfn;
208 #endif
209 if (dma) {
210 init_emergency_isa_pool();
211 q->bounce_gfp = GFP_NOIO | GFP_DMA;
212 q->limits.bounce_pfn = b_pfn;
215 EXPORT_SYMBOL(blk_queue_bounce_limit);
218 * blk_limits_max_hw_sectors - set hard and soft limit of max sectors for request
219 * @limits: the queue limits
220 * @max_hw_sectors: max hardware sectors in the usual 512b unit
222 * Description:
223 * Enables a low level driver to set a hard upper limit,
224 * max_hw_sectors, on the size of requests. max_hw_sectors is set by
225 * the device driver based upon the combined capabilities of I/O
226 * controller and storage device.
228 * max_sectors is a soft limit imposed by the block layer for
229 * filesystem type requests. This value can be overridden on a
230 * per-device basis in /sys/block/<device>/queue/max_sectors_kb.
231 * The soft limit can not exceed max_hw_sectors.
233 void blk_limits_max_hw_sectors(struct queue_limits *limits, unsigned int max_hw_sectors)
235 if ((max_hw_sectors << 9) < PAGE_CACHE_SIZE) {
236 max_hw_sectors = 1 << (PAGE_CACHE_SHIFT - 9);
237 printk(KERN_INFO "%s: set to minimum %d\n",
238 __func__, max_hw_sectors);
241 limits->max_hw_sectors = max_hw_sectors;
242 limits->max_sectors = min_t(unsigned int, max_hw_sectors,
243 BLK_DEF_MAX_SECTORS);
245 EXPORT_SYMBOL(blk_limits_max_hw_sectors);
248 * blk_queue_max_hw_sectors - set max sectors for a request for this queue
249 * @q: the request queue for the device
250 * @max_hw_sectors: max hardware sectors in the usual 512b unit
252 * Description:
253 * See description for blk_limits_max_hw_sectors().
255 void blk_queue_max_hw_sectors(struct request_queue *q, unsigned int max_hw_sectors)
257 blk_limits_max_hw_sectors(&q->limits, max_hw_sectors);
259 EXPORT_SYMBOL(blk_queue_max_hw_sectors);
262 * blk_queue_max_discard_sectors - set max sectors for a single discard
263 * @q: the request queue for the device
264 * @max_discard_sectors: maximum number of sectors to discard
266 void blk_queue_max_discard_sectors(struct request_queue *q,
267 unsigned int max_discard_sectors)
269 q->limits.max_discard_sectors = max_discard_sectors;
271 EXPORT_SYMBOL(blk_queue_max_discard_sectors);
274 * blk_queue_max_segments - set max hw segments for a request for this queue
275 * @q: the request queue for the device
276 * @max_segments: max number of segments
278 * Description:
279 * Enables a low level driver to set an upper limit on the number of
280 * hw data segments in a request.
282 void blk_queue_max_segments(struct request_queue *q, unsigned short max_segments)
284 if (!max_segments) {
285 max_segments = 1;
286 printk(KERN_INFO "%s: set to minimum %d\n",
287 __func__, max_segments);
290 q->limits.max_segments = max_segments;
292 EXPORT_SYMBOL(blk_queue_max_segments);
295 * blk_queue_max_segment_size - set max segment size for blk_rq_map_sg
296 * @q: the request queue for the device
297 * @max_size: max size of segment in bytes
299 * Description:
300 * Enables a low level driver to set an upper limit on the size of a
301 * coalesced segment
303 void blk_queue_max_segment_size(struct request_queue *q, unsigned int max_size)
305 if (max_size < PAGE_CACHE_SIZE) {
306 max_size = PAGE_CACHE_SIZE;
307 printk(KERN_INFO "%s: set to minimum %d\n",
308 __func__, max_size);
311 q->limits.max_segment_size = max_size;
313 EXPORT_SYMBOL(blk_queue_max_segment_size);
316 * blk_queue_logical_block_size - set logical block size for the queue
317 * @q: the request queue for the device
318 * @size: the logical block size, in bytes
320 * Description:
321 * This should be set to the lowest possible block size that the
322 * storage device can address. The default of 512 covers most
323 * hardware.
325 void blk_queue_logical_block_size(struct request_queue *q, unsigned short size)
327 q->limits.logical_block_size = size;
329 if (q->limits.physical_block_size < size)
330 q->limits.physical_block_size = size;
332 if (q->limits.io_min < q->limits.physical_block_size)
333 q->limits.io_min = q->limits.physical_block_size;
335 EXPORT_SYMBOL(blk_queue_logical_block_size);
338 * blk_queue_physical_block_size - set physical block size for the queue
339 * @q: the request queue for the device
340 * @size: the physical block size, in bytes
342 * Description:
343 * This should be set to the lowest possible sector size that the
344 * hardware can operate on without reverting to read-modify-write
345 * operations.
347 void blk_queue_physical_block_size(struct request_queue *q, unsigned int size)
349 q->limits.physical_block_size = size;
351 if (q->limits.physical_block_size < q->limits.logical_block_size)
352 q->limits.physical_block_size = q->limits.logical_block_size;
354 if (q->limits.io_min < q->limits.physical_block_size)
355 q->limits.io_min = q->limits.physical_block_size;
357 EXPORT_SYMBOL(blk_queue_physical_block_size);
360 * blk_queue_alignment_offset - set physical block alignment offset
361 * @q: the request queue for the device
362 * @offset: alignment offset in bytes
364 * Description:
365 * Some devices are naturally misaligned to compensate for things like
366 * the legacy DOS partition table 63-sector offset. Low-level drivers
367 * should call this function for devices whose first sector is not
368 * naturally aligned.
370 void blk_queue_alignment_offset(struct request_queue *q, unsigned int offset)
372 q->limits.alignment_offset =
373 offset & (q->limits.physical_block_size - 1);
374 q->limits.misaligned = 0;
376 EXPORT_SYMBOL(blk_queue_alignment_offset);
379 * blk_limits_io_min - set minimum request size for a device
380 * @limits: the queue limits
381 * @min: smallest I/O size in bytes
383 * Description:
384 * Some devices have an internal block size bigger than the reported
385 * hardware sector size. This function can be used to signal the
386 * smallest I/O the device can perform without incurring a performance
387 * penalty.
389 void blk_limits_io_min(struct queue_limits *limits, unsigned int min)
391 limits->io_min = min;
393 if (limits->io_min < limits->logical_block_size)
394 limits->io_min = limits->logical_block_size;
396 if (limits->io_min < limits->physical_block_size)
397 limits->io_min = limits->physical_block_size;
399 EXPORT_SYMBOL(blk_limits_io_min);
402 * blk_queue_io_min - set minimum request size for the queue
403 * @q: the request queue for the device
404 * @min: smallest I/O size in bytes
406 * Description:
407 * Storage devices may report a granularity or preferred minimum I/O
408 * size which is the smallest request the device can perform without
409 * incurring a performance penalty. For disk drives this is often the
410 * physical block size. For RAID arrays it is often the stripe chunk
411 * size. A properly aligned multiple of minimum_io_size is the
412 * preferred request size for workloads where a high number of I/O
413 * operations is desired.
415 void blk_queue_io_min(struct request_queue *q, unsigned int min)
417 blk_limits_io_min(&q->limits, min);
419 EXPORT_SYMBOL(blk_queue_io_min);
422 * blk_limits_io_opt - set optimal request size for a device
423 * @limits: the queue limits
424 * @opt: smallest I/O size in bytes
426 * Description:
427 * Storage devices may report an optimal I/O size, which is the
428 * device's preferred unit for sustained I/O. This is rarely reported
429 * for disk drives. For RAID arrays it is usually the stripe width or
430 * the internal track size. A properly aligned multiple of
431 * optimal_io_size is the preferred request size for workloads where
432 * sustained throughput is desired.
434 void blk_limits_io_opt(struct queue_limits *limits, unsigned int opt)
436 limits->io_opt = opt;
438 EXPORT_SYMBOL(blk_limits_io_opt);
441 * blk_queue_io_opt - set optimal request size for the queue
442 * @q: the request queue for the device
443 * @opt: optimal request size in bytes
445 * Description:
446 * Storage devices may report an optimal I/O size, which is the
447 * device's preferred unit for sustained I/O. This is rarely reported
448 * for disk drives. For RAID arrays it is usually the stripe width or
449 * the internal track size. A properly aligned multiple of
450 * optimal_io_size is the preferred request size for workloads where
451 * sustained throughput is desired.
453 void blk_queue_io_opt(struct request_queue *q, unsigned int opt)
455 blk_limits_io_opt(&q->limits, opt);
457 EXPORT_SYMBOL(blk_queue_io_opt);
460 * blk_queue_stack_limits - inherit underlying queue limits for stacked drivers
461 * @t: the stacking driver (top)
462 * @b: the underlying device (bottom)
464 void blk_queue_stack_limits(struct request_queue *t, struct request_queue *b)
466 blk_stack_limits(&t->limits, &b->limits, 0);
468 EXPORT_SYMBOL(blk_queue_stack_limits);
471 * blk_stack_limits - adjust queue_limits for stacked devices
472 * @t: the stacking driver limits (top device)
473 * @b: the underlying queue limits (bottom, component device)
474 * @start: first data sector within component device
476 * Description:
477 * This function is used by stacking drivers like MD and DM to ensure
478 * that all component devices have compatible block sizes and
479 * alignments. The stacking driver must provide a queue_limits
480 * struct (top) and then iteratively call the stacking function for
481 * all component (bottom) devices. The stacking function will
482 * attempt to combine the values and ensure proper alignment.
484 * Returns 0 if the top and bottom queue_limits are compatible. The
485 * top device's block sizes and alignment offsets may be adjusted to
486 * ensure alignment with the bottom device. If no compatible sizes
487 * and alignments exist, -1 is returned and the resulting top
488 * queue_limits will have the misaligned flag set to indicate that
489 * the alignment_offset is undefined.
491 int blk_stack_limits(struct queue_limits *t, struct queue_limits *b,
492 sector_t start)
494 unsigned int top, bottom, alignment, ret = 0;
496 t->max_sectors = min_not_zero(t->max_sectors, b->max_sectors);
497 t->max_hw_sectors = min_not_zero(t->max_hw_sectors, b->max_hw_sectors);
498 t->bounce_pfn = min_not_zero(t->bounce_pfn, b->bounce_pfn);
500 t->seg_boundary_mask = min_not_zero(t->seg_boundary_mask,
501 b->seg_boundary_mask);
503 t->max_segments = min_not_zero(t->max_segments, b->max_segments);
504 t->max_integrity_segments = min_not_zero(t->max_integrity_segments,
505 b->max_integrity_segments);
507 t->max_segment_size = min_not_zero(t->max_segment_size,
508 b->max_segment_size);
510 t->misaligned |= b->misaligned;
512 alignment = queue_limit_alignment_offset(b, start);
514 /* Bottom device has different alignment. Check that it is
515 * compatible with the current top alignment.
517 if (t->alignment_offset != alignment) {
519 top = max(t->physical_block_size, t->io_min)
520 + t->alignment_offset;
521 bottom = max(b->physical_block_size, b->io_min) + alignment;
523 /* Verify that top and bottom intervals line up */
524 if (max(top, bottom) & (min(top, bottom) - 1)) {
525 t->misaligned = 1;
526 ret = -1;
530 t->logical_block_size = max(t->logical_block_size,
531 b->logical_block_size);
533 t->physical_block_size = max(t->physical_block_size,
534 b->physical_block_size);
536 t->io_min = max(t->io_min, b->io_min);
537 t->io_opt = lcm(t->io_opt, b->io_opt);
539 t->cluster &= b->cluster;
540 t->discard_zeroes_data &= b->discard_zeroes_data;
542 /* Physical block size a multiple of the logical block size? */
543 if (t->physical_block_size & (t->logical_block_size - 1)) {
544 t->physical_block_size = t->logical_block_size;
545 t->misaligned = 1;
546 ret = -1;
549 /* Minimum I/O a multiple of the physical block size? */
550 if (t->io_min & (t->physical_block_size - 1)) {
551 t->io_min = t->physical_block_size;
552 t->misaligned = 1;
553 ret = -1;
556 /* Optimal I/O a multiple of the physical block size? */
557 if (t->io_opt & (t->physical_block_size - 1)) {
558 t->io_opt = 0;
559 t->misaligned = 1;
560 ret = -1;
563 /* Find lowest common alignment_offset */
564 t->alignment_offset = lcm(t->alignment_offset, alignment)
565 & (max(t->physical_block_size, t->io_min) - 1);
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;
573 /* Discard alignment and granularity */
574 if (b->discard_granularity) {
575 alignment = queue_limit_discard_alignment(b, start);
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;
582 /* Verify that top and bottom intervals line up */
583 if (max(top, bottom) & (min(top, bottom) - 1))
584 t->discard_misaligned = 1;
587 t->max_discard_sectors = min_not_zero(t->max_discard_sectors,
588 b->max_discard_sectors);
589 t->discard_granularity = max(t->discard_granularity,
590 b->discard_granularity);
591 t->discard_alignment = lcm(t->discard_alignment, alignment) &
592 (t->discard_granularity - 1);
595 return ret;
597 EXPORT_SYMBOL(blk_stack_limits);
600 * bdev_stack_limits - adjust queue limits for stacked drivers
601 * @t: the stacking driver limits (top device)
602 * @bdev: the component block_device (bottom)
603 * @start: first data sector within component device
605 * Description:
606 * Merges queue limits for a top device and a block_device. Returns
607 * 0 if alignment didn't change. Returns -1 if adding the bottom
608 * device caused misalignment.
610 int bdev_stack_limits(struct queue_limits *t, struct block_device *bdev,
611 sector_t start)
613 struct request_queue *bq = bdev_get_queue(bdev);
615 start += get_start_sect(bdev);
617 return blk_stack_limits(t, &bq->limits, start);
619 EXPORT_SYMBOL(bdev_stack_limits);
622 * disk_stack_limits - adjust queue limits for stacked drivers
623 * @disk: MD/DM gendisk (top)
624 * @bdev: the underlying block device (bottom)
625 * @offset: offset to beginning of data within component device
627 * Description:
628 * Merges the limits for a top level gendisk and a bottom level
629 * block_device.
631 void disk_stack_limits(struct gendisk *disk, struct block_device *bdev,
632 sector_t offset)
634 struct request_queue *t = disk->queue;
636 if (bdev_stack_limits(&t->limits, bdev, offset >> 9) < 0) {
637 char top[BDEVNAME_SIZE], bottom[BDEVNAME_SIZE];
639 disk_name(disk, 0, top);
640 bdevname(bdev, bottom);
642 printk(KERN_NOTICE "%s: Warning: Device %s is misaligned\n",
643 top, bottom);
646 EXPORT_SYMBOL(disk_stack_limits);
649 * blk_queue_dma_pad - set pad mask
650 * @q: the request queue for the device
651 * @mask: pad mask
653 * Set dma pad mask.
655 * Appending pad buffer to a request modifies the last entry of a
656 * scatter list such that it includes the pad buffer.
658 void blk_queue_dma_pad(struct request_queue *q, unsigned int mask)
660 q->dma_pad_mask = mask;
662 EXPORT_SYMBOL(blk_queue_dma_pad);
665 * blk_queue_update_dma_pad - update pad mask
666 * @q: the request queue for the device
667 * @mask: pad mask
669 * Update dma pad mask.
671 * Appending pad buffer to a request modifies the last entry of a
672 * scatter list such that it includes the pad buffer.
674 void blk_queue_update_dma_pad(struct request_queue *q, unsigned int mask)
676 if (mask > q->dma_pad_mask)
677 q->dma_pad_mask = mask;
679 EXPORT_SYMBOL(blk_queue_update_dma_pad);
682 * blk_queue_dma_drain - Set up a drain buffer for excess dma.
683 * @q: the request queue for the device
684 * @dma_drain_needed: fn which returns non-zero if drain is necessary
685 * @buf: physically contiguous buffer
686 * @size: size of the buffer in bytes
688 * Some devices have excess DMA problems and can't simply discard (or
689 * zero fill) the unwanted piece of the transfer. They have to have a
690 * real area of memory to transfer it into. The use case for this is
691 * ATAPI devices in DMA mode. If the packet command causes a transfer
692 * bigger than the transfer size some HBAs will lock up if there
693 * aren't DMA elements to contain the excess transfer. What this API
694 * does is adjust the queue so that the buf is always appended
695 * silently to the scatterlist.
697 * Note: This routine adjusts max_hw_segments to make room for appending
698 * the drain buffer. If you call blk_queue_max_segments() after calling
699 * this routine, you must set the limit to one fewer than your device
700 * can support otherwise there won't be room for the drain buffer.
702 int blk_queue_dma_drain(struct request_queue *q,
703 dma_drain_needed_fn *dma_drain_needed,
704 void *buf, unsigned int size)
706 if (queue_max_segments(q) < 2)
707 return -EINVAL;
708 /* make room for appending the drain */
709 blk_queue_max_segments(q, queue_max_segments(q) - 1);
710 q->dma_drain_needed = dma_drain_needed;
711 q->dma_drain_buffer = buf;
712 q->dma_drain_size = size;
714 return 0;
716 EXPORT_SYMBOL_GPL(blk_queue_dma_drain);
719 * blk_queue_segment_boundary - set boundary rules for segment merging
720 * @q: the request queue for the device
721 * @mask: the memory boundary mask
723 void blk_queue_segment_boundary(struct request_queue *q, unsigned long mask)
725 if (mask < PAGE_CACHE_SIZE - 1) {
726 mask = PAGE_CACHE_SIZE - 1;
727 printk(KERN_INFO "%s: set to minimum %lx\n",
728 __func__, mask);
731 q->limits.seg_boundary_mask = mask;
733 EXPORT_SYMBOL(blk_queue_segment_boundary);
736 * blk_queue_dma_alignment - set dma length and memory alignment
737 * @q: the request queue for the device
738 * @mask: alignment mask
740 * description:
741 * set required memory and length alignment for direct dma transactions.
742 * this is used when building direct io requests for the queue.
745 void blk_queue_dma_alignment(struct request_queue *q, int mask)
747 q->dma_alignment = mask;
749 EXPORT_SYMBOL(blk_queue_dma_alignment);
752 * blk_queue_update_dma_alignment - update dma length and memory alignment
753 * @q: the request queue for the device
754 * @mask: alignment mask
756 * description:
757 * update required memory and length alignment for direct dma transactions.
758 * If the requested alignment is larger than the current alignment, then
759 * the current queue alignment is updated to the new value, otherwise it
760 * is left alone. The design of this is to allow multiple objects
761 * (driver, device, transport etc) to set their respective
762 * alignments without having them interfere.
765 void blk_queue_update_dma_alignment(struct request_queue *q, int mask)
767 BUG_ON(mask > PAGE_SIZE);
769 if (mask > q->dma_alignment)
770 q->dma_alignment = mask;
772 EXPORT_SYMBOL(blk_queue_update_dma_alignment);
775 * blk_queue_flush - configure queue's cache flush capability
776 * @q: the request queue for the device
777 * @flush: 0, REQ_FLUSH or REQ_FLUSH | REQ_FUA
779 * Tell block layer cache flush capability of @q. If it supports
780 * flushing, REQ_FLUSH should be set. If it supports bypassing
781 * write cache for individual writes, REQ_FUA should be set.
783 void blk_queue_flush(struct request_queue *q, unsigned int flush)
785 WARN_ON_ONCE(flush & ~(REQ_FLUSH | REQ_FUA));
787 if (WARN_ON_ONCE(!(flush & REQ_FLUSH) && (flush & REQ_FUA)))
788 flush &= ~REQ_FUA;
790 q->flush_flags = flush & (REQ_FLUSH | REQ_FUA);
792 EXPORT_SYMBOL_GPL(blk_queue_flush);
794 void blk_queue_flush_queueable(struct request_queue *q, bool queueable)
796 q->flush_not_queueable = !queueable;
798 EXPORT_SYMBOL_GPL(blk_queue_flush_queueable);
800 static int __init blk_settings_init(void)
802 blk_max_low_pfn = max_low_pfn - 1;
803 blk_max_pfn = max_pfn - 1;
804 return 0;
806 subsys_initcall(blk_settings_init);