2 * Functions related to setting various queue properties from drivers
4 #include <linux/kernel.h>
5 #include <linux/module.h>
6 #include <linux/init.h>
8 #include <linux/blkdev.h>
9 #include <linux/memblock.h> /* for max_pfn/max_low_pfn */
10 #include <linux/gcd.h>
11 #include <linux/lcm.h>
12 #include <linux/jiffies.h>
13 #include <linux/gfp.h>
18 unsigned long blk_max_low_pfn;
19 EXPORT_SYMBOL(blk_max_low_pfn);
21 unsigned long blk_max_pfn;
23 void blk_queue_rq_timeout(struct request_queue *q, unsigned int timeout)
25 q->rq_timeout = timeout;
27 EXPORT_SYMBOL_GPL(blk_queue_rq_timeout);
30 * blk_set_default_limits - reset limits to default values
31 * @lim: the queue_limits structure to reset
34 * Returns a queue_limit struct to its default state.
36 void blk_set_default_limits(struct queue_limits *lim)
38 lim->max_segments = BLK_MAX_SEGMENTS;
39 lim->max_discard_segments = 1;
40 lim->max_integrity_segments = 0;
41 lim->seg_boundary_mask = BLK_SEG_BOUNDARY_MASK;
42 lim->virt_boundary_mask = 0;
43 lim->max_segment_size = BLK_MAX_SEGMENT_SIZE;
44 lim->max_sectors = lim->max_hw_sectors = BLK_SAFE_MAX_SECTORS;
45 lim->max_dev_sectors = 0;
46 lim->chunk_sectors = 0;
47 lim->max_write_same_sectors = 0;
48 lim->max_write_zeroes_sectors = 0;
49 lim->max_discard_sectors = 0;
50 lim->max_hw_discard_sectors = 0;
51 lim->discard_granularity = 0;
52 lim->discard_alignment = 0;
53 lim->discard_misaligned = 0;
54 lim->logical_block_size = lim->physical_block_size = lim->io_min = 512;
55 lim->bounce_pfn = (unsigned long)(BLK_BOUNCE_ANY >> PAGE_SHIFT);
56 lim->alignment_offset = 0;
60 lim->zoned = BLK_ZONED_NONE;
62 EXPORT_SYMBOL(blk_set_default_limits);
65 * blk_set_stacking_limits - set default limits for stacking devices
66 * @lim: the queue_limits structure to reset
69 * Returns a queue_limit struct to its default state. Should be used
70 * by stacking drivers like DM that have no internal limits.
72 void blk_set_stacking_limits(struct queue_limits *lim)
74 blk_set_default_limits(lim);
76 /* Inherit limits from component devices */
77 lim->max_segments = USHRT_MAX;
78 lim->max_discard_segments = USHRT_MAX;
79 lim->max_hw_sectors = UINT_MAX;
80 lim->max_segment_size = UINT_MAX;
81 lim->max_sectors = UINT_MAX;
82 lim->max_dev_sectors = UINT_MAX;
83 lim->max_write_same_sectors = UINT_MAX;
84 lim->max_write_zeroes_sectors = UINT_MAX;
86 EXPORT_SYMBOL(blk_set_stacking_limits);
89 * blk_queue_make_request - define an alternate make_request function for a device
90 * @q: the request queue for the device to be affected
91 * @mfn: the alternate make_request function
94 * The normal way for &struct bios to be passed to a device
95 * driver is for them to be collected into requests on a request
96 * queue, and then to allow the device driver to select requests
97 * off that queue when it is ready. This works well for many block
98 * devices. However some block devices (typically virtual devices
99 * such as md or lvm) do not benefit from the processing on the
100 * request queue, and are served best by having the requests passed
101 * directly to them. This can be achieved by providing a function
102 * to blk_queue_make_request().
105 * The driver that does this *must* be able to deal appropriately
106 * with buffers in "highmemory". This can be accomplished by either calling
107 * kmap_atomic() to get a temporary kernel mapping, or by calling
108 * blk_queue_bounce() to create a buffer in normal memory.
110 void blk_queue_make_request(struct request_queue *q, make_request_fn *mfn)
115 q->nr_requests = BLKDEV_MAX_RQ;
117 q->make_request_fn = mfn;
118 blk_queue_dma_alignment(q, 511);
120 blk_set_default_limits(&q->limits);
122 EXPORT_SYMBOL(blk_queue_make_request);
125 * blk_queue_bounce_limit - set bounce buffer limit for queue
126 * @q: the request queue for the device
127 * @max_addr: the maximum address the device can handle
130 * Different hardware can have different requirements as to what pages
131 * it can do I/O directly to. A low level driver can call
132 * blk_queue_bounce_limit to have lower memory pages allocated as bounce
133 * buffers for doing I/O to pages residing above @max_addr.
135 void blk_queue_bounce_limit(struct request_queue *q, u64 max_addr)
137 unsigned long b_pfn = max_addr >> PAGE_SHIFT;
140 q->bounce_gfp = GFP_NOIO;
141 #if BITS_PER_LONG == 64
143 * Assume anything <= 4GB can be handled by IOMMU. Actually
144 * some IOMMUs can handle everything, but I don't know of a
145 * way to test this here.
147 if (b_pfn < (min_t(u64, 0xffffffffUL, BLK_BOUNCE_HIGH) >> PAGE_SHIFT))
149 q->limits.bounce_pfn = max(max_low_pfn, b_pfn);
151 if (b_pfn < blk_max_low_pfn)
153 q->limits.bounce_pfn = b_pfn;
156 init_emergency_isa_pool();
157 q->bounce_gfp = GFP_NOIO | GFP_DMA;
158 q->limits.bounce_pfn = b_pfn;
161 EXPORT_SYMBOL(blk_queue_bounce_limit);
164 * blk_queue_max_hw_sectors - set max sectors for a request for this queue
165 * @q: the request queue for the device
166 * @max_hw_sectors: max hardware sectors in the usual 512b unit
169 * Enables a low level driver to set a hard upper limit,
170 * max_hw_sectors, on the size of requests. max_hw_sectors is set by
171 * the device driver based upon the capabilities of the I/O
174 * max_dev_sectors is a hard limit imposed by the storage device for
175 * READ/WRITE requests. It is set by the disk driver.
177 * max_sectors is a soft limit imposed by the block layer for
178 * filesystem type requests. This value can be overridden on a
179 * per-device basis in /sys/block/<device>/queue/max_sectors_kb.
180 * The soft limit can not exceed max_hw_sectors.
182 void blk_queue_max_hw_sectors(struct request_queue *q, unsigned int max_hw_sectors)
184 struct queue_limits *limits = &q->limits;
185 unsigned int max_sectors;
187 if ((max_hw_sectors << 9) < PAGE_SIZE) {
188 max_hw_sectors = 1 << (PAGE_SHIFT - 9);
189 printk(KERN_INFO "%s: set to minimum %d\n",
190 __func__, max_hw_sectors);
193 limits->max_hw_sectors = max_hw_sectors;
194 max_sectors = min_not_zero(max_hw_sectors, limits->max_dev_sectors);
195 max_sectors = min_t(unsigned int, max_sectors, BLK_DEF_MAX_SECTORS);
196 limits->max_sectors = max_sectors;
197 q->backing_dev_info->io_pages = max_sectors >> (PAGE_SHIFT - 9);
199 EXPORT_SYMBOL(blk_queue_max_hw_sectors);
202 * blk_queue_chunk_sectors - set size of the chunk for this queue
203 * @q: the request queue for the device
204 * @chunk_sectors: chunk sectors in the usual 512b unit
207 * If a driver doesn't want IOs to cross a given chunk size, it can set
208 * this limit and prevent merging across chunks. Note that the chunk size
209 * must currently be a power-of-2 in sectors. Also note that the block
210 * layer must accept a page worth of data at any offset. So if the
211 * crossing of chunks is a hard limitation in the driver, it must still be
212 * prepared to split single page bios.
214 void blk_queue_chunk_sectors(struct request_queue *q, unsigned int chunk_sectors)
216 BUG_ON(!is_power_of_2(chunk_sectors));
217 q->limits.chunk_sectors = chunk_sectors;
219 EXPORT_SYMBOL(blk_queue_chunk_sectors);
222 * blk_queue_max_discard_sectors - set max sectors for a single discard
223 * @q: the request queue for the device
224 * @max_discard_sectors: maximum number of sectors to discard
226 void blk_queue_max_discard_sectors(struct request_queue *q,
227 unsigned int max_discard_sectors)
229 q->limits.max_hw_discard_sectors = max_discard_sectors;
230 q->limits.max_discard_sectors = max_discard_sectors;
232 EXPORT_SYMBOL(blk_queue_max_discard_sectors);
235 * blk_queue_max_write_same_sectors - set max sectors for a single write same
236 * @q: the request queue for the device
237 * @max_write_same_sectors: maximum number of sectors to write per command
239 void blk_queue_max_write_same_sectors(struct request_queue *q,
240 unsigned int max_write_same_sectors)
242 q->limits.max_write_same_sectors = max_write_same_sectors;
244 EXPORT_SYMBOL(blk_queue_max_write_same_sectors);
247 * blk_queue_max_write_zeroes_sectors - set max sectors for a single
249 * @q: the request queue for the device
250 * @max_write_zeroes_sectors: maximum number of sectors to write per command
252 void blk_queue_max_write_zeroes_sectors(struct request_queue *q,
253 unsigned int max_write_zeroes_sectors)
255 q->limits.max_write_zeroes_sectors = max_write_zeroes_sectors;
257 EXPORT_SYMBOL(blk_queue_max_write_zeroes_sectors);
260 * blk_queue_max_segments - set max hw segments for a request for this queue
261 * @q: the request queue for the device
262 * @max_segments: max number of segments
265 * Enables a low level driver to set an upper limit on the number of
266 * hw data segments in a request.
268 void blk_queue_max_segments(struct request_queue *q, unsigned short max_segments)
272 printk(KERN_INFO "%s: set to minimum %d\n",
273 __func__, max_segments);
276 q->limits.max_segments = max_segments;
278 EXPORT_SYMBOL(blk_queue_max_segments);
281 * blk_queue_max_discard_segments - set max segments for discard requests
282 * @q: the request queue for the device
283 * @max_segments: max number of segments
286 * Enables a low level driver to set an upper limit on the number of
287 * segments in a discard request.
289 void blk_queue_max_discard_segments(struct request_queue *q,
290 unsigned short max_segments)
292 q->limits.max_discard_segments = max_segments;
294 EXPORT_SYMBOL_GPL(blk_queue_max_discard_segments);
297 * blk_queue_max_segment_size - set max segment size for blk_rq_map_sg
298 * @q: the request queue for the device
299 * @max_size: max size of segment in bytes
302 * Enables a low level driver to set an upper limit on the size of a
305 void blk_queue_max_segment_size(struct request_queue *q, unsigned int max_size)
307 if (max_size < PAGE_SIZE) {
308 max_size = PAGE_SIZE;
309 printk(KERN_INFO "%s: set to minimum %d\n",
313 q->limits.max_segment_size = max_size;
315 EXPORT_SYMBOL(blk_queue_max_segment_size);
318 * blk_queue_logical_block_size - set logical block size for the queue
319 * @q: the request queue for the device
320 * @size: the logical block size, in bytes
323 * This should be set to the lowest possible block size that the
324 * storage device can address. The default of 512 covers most
327 void blk_queue_logical_block_size(struct request_queue *q, unsigned short size)
329 q->limits.logical_block_size = size;
331 if (q->limits.physical_block_size < size)
332 q->limits.physical_block_size = size;
334 if (q->limits.io_min < q->limits.physical_block_size)
335 q->limits.io_min = q->limits.physical_block_size;
337 EXPORT_SYMBOL(blk_queue_logical_block_size);
340 * blk_queue_physical_block_size - set physical block size for the queue
341 * @q: the request queue for the device
342 * @size: the physical block size, in bytes
345 * This should be set to the lowest possible sector size that the
346 * hardware can operate on without reverting to read-modify-write
349 void blk_queue_physical_block_size(struct request_queue *q, unsigned int size)
351 q->limits.physical_block_size = size;
353 if (q->limits.physical_block_size < q->limits.logical_block_size)
354 q->limits.physical_block_size = q->limits.logical_block_size;
356 if (q->limits.io_min < q->limits.physical_block_size)
357 q->limits.io_min = q->limits.physical_block_size;
359 EXPORT_SYMBOL(blk_queue_physical_block_size);
362 * blk_queue_alignment_offset - set physical block alignment offset
363 * @q: the request queue for the device
364 * @offset: alignment offset in bytes
367 * Some devices are naturally misaligned to compensate for things like
368 * the legacy DOS partition table 63-sector offset. Low-level drivers
369 * should call this function for devices whose first sector is not
372 void blk_queue_alignment_offset(struct request_queue *q, unsigned int offset)
374 q->limits.alignment_offset =
375 offset & (q->limits.physical_block_size - 1);
376 q->limits.misaligned = 0;
378 EXPORT_SYMBOL(blk_queue_alignment_offset);
381 * blk_limits_io_min - set minimum request size for a device
382 * @limits: the queue limits
383 * @min: smallest I/O size in bytes
386 * Some devices have an internal block size bigger than the reported
387 * hardware sector size. This function can be used to signal the
388 * smallest I/O the device can perform without incurring a performance
391 void blk_limits_io_min(struct queue_limits *limits, unsigned int min)
393 limits->io_min = min;
395 if (limits->io_min < limits->logical_block_size)
396 limits->io_min = limits->logical_block_size;
398 if (limits->io_min < limits->physical_block_size)
399 limits->io_min = limits->physical_block_size;
401 EXPORT_SYMBOL(blk_limits_io_min);
404 * blk_queue_io_min - set minimum request size for the queue
405 * @q: the request queue for the device
406 * @min: smallest I/O size in bytes
409 * Storage devices may report a granularity or preferred minimum I/O
410 * size which is the smallest request the device can perform without
411 * incurring a performance penalty. For disk drives this is often the
412 * physical block size. For RAID arrays it is often the stripe chunk
413 * size. A properly aligned multiple of minimum_io_size is the
414 * preferred request size for workloads where a high number of I/O
415 * operations is desired.
417 void blk_queue_io_min(struct request_queue *q, unsigned int min)
419 blk_limits_io_min(&q->limits, min);
421 EXPORT_SYMBOL(blk_queue_io_min);
424 * blk_limits_io_opt - set optimal request size for a device
425 * @limits: the queue limits
426 * @opt: smallest I/O size in bytes
429 * Storage devices may report an optimal I/O size, which is the
430 * device's preferred unit for sustained I/O. This is rarely reported
431 * for disk drives. For RAID arrays it is usually the stripe width or
432 * the internal track size. A properly aligned multiple of
433 * optimal_io_size is the preferred request size for workloads where
434 * sustained throughput is desired.
436 void blk_limits_io_opt(struct queue_limits *limits, unsigned int opt)
438 limits->io_opt = opt;
440 EXPORT_SYMBOL(blk_limits_io_opt);
443 * blk_queue_io_opt - set optimal request size for the queue
444 * @q: the request queue for the device
445 * @opt: optimal request size in bytes
448 * Storage devices may report an optimal I/O size, which is the
449 * device's preferred unit for sustained I/O. This is rarely reported
450 * for disk drives. For RAID arrays it is usually the stripe width or
451 * the internal track size. A properly aligned multiple of
452 * optimal_io_size is the preferred request size for workloads where
453 * sustained throughput is desired.
455 void blk_queue_io_opt(struct request_queue *q, unsigned int opt)
457 blk_limits_io_opt(&q->limits, opt);
459 EXPORT_SYMBOL(blk_queue_io_opt);
462 * blk_queue_stack_limits - inherit underlying queue limits for stacked drivers
463 * @t: the stacking driver (top)
464 * @b: the underlying device (bottom)
466 void blk_queue_stack_limits(struct request_queue *t, struct request_queue *b)
468 blk_stack_limits(&t->limits, &b->limits, 0);
470 EXPORT_SYMBOL(blk_queue_stack_limits);
473 * blk_stack_limits - adjust queue_limits for stacked devices
474 * @t: the stacking driver limits (top device)
475 * @b: the underlying queue limits (bottom, component device)
476 * @start: first data sector within component device
479 * This function is used by stacking drivers like MD and DM to ensure
480 * that all component devices have compatible block sizes and
481 * alignments. The stacking driver must provide a queue_limits
482 * struct (top) and then iteratively call the stacking function for
483 * all component (bottom) devices. The stacking function will
484 * attempt to combine the values and ensure proper alignment.
486 * Returns 0 if the top and bottom queue_limits are compatible. The
487 * top device's block sizes and alignment offsets may be adjusted to
488 * ensure alignment with the bottom device. If no compatible sizes
489 * and alignments exist, -1 is returned and the resulting top
490 * queue_limits will have the misaligned flag set to indicate that
491 * the alignment_offset is undefined.
493 int blk_stack_limits(struct queue_limits *t, struct queue_limits *b,
496 unsigned int top, bottom, alignment, ret = 0;
498 t->max_sectors = min_not_zero(t->max_sectors, b->max_sectors);
499 t->max_hw_sectors = min_not_zero(t->max_hw_sectors, b->max_hw_sectors);
500 t->max_dev_sectors = min_not_zero(t->max_dev_sectors, b->max_dev_sectors);
501 t->max_write_same_sectors = min(t->max_write_same_sectors,
502 b->max_write_same_sectors);
503 t->max_write_zeroes_sectors = min(t->max_write_zeroes_sectors,
504 b->max_write_zeroes_sectors);
505 t->bounce_pfn = min_not_zero(t->bounce_pfn, b->bounce_pfn);
507 t->seg_boundary_mask = min_not_zero(t->seg_boundary_mask,
508 b->seg_boundary_mask);
509 t->virt_boundary_mask = min_not_zero(t->virt_boundary_mask,
510 b->virt_boundary_mask);
512 t->max_segments = min_not_zero(t->max_segments, b->max_segments);
513 t->max_discard_segments = min_not_zero(t->max_discard_segments,
514 b->max_discard_segments);
515 t->max_integrity_segments = min_not_zero(t->max_integrity_segments,
516 b->max_integrity_segments);
518 t->max_segment_size = min_not_zero(t->max_segment_size,
519 b->max_segment_size);
521 t->misaligned |= b->misaligned;
523 alignment = queue_limit_alignment_offset(b, start);
525 /* Bottom device has different alignment. Check that it is
526 * compatible with the current top alignment.
528 if (t->alignment_offset != alignment) {
530 top = max(t->physical_block_size, t->io_min)
531 + t->alignment_offset;
532 bottom = max(b->physical_block_size, b->io_min) + alignment;
534 /* Verify that top and bottom intervals line up */
535 if (max(top, bottom) % min(top, bottom)) {
541 t->logical_block_size = max(t->logical_block_size,
542 b->logical_block_size);
544 t->physical_block_size = max(t->physical_block_size,
545 b->physical_block_size);
547 t->io_min = max(t->io_min, b->io_min);
548 t->io_opt = lcm_not_zero(t->io_opt, b->io_opt);
550 t->cluster &= b->cluster;
552 /* Physical block size a multiple of the logical block size? */
553 if (t->physical_block_size & (t->logical_block_size - 1)) {
554 t->physical_block_size = t->logical_block_size;
559 /* Minimum I/O a multiple of the physical block size? */
560 if (t->io_min & (t->physical_block_size - 1)) {
561 t->io_min = t->physical_block_size;
566 /* Optimal I/O a multiple of the physical block size? */
567 if (t->io_opt & (t->physical_block_size - 1)) {
573 t->raid_partial_stripes_expensive =
574 max(t->raid_partial_stripes_expensive,
575 b->raid_partial_stripes_expensive);
577 /* Find lowest common alignment_offset */
578 t->alignment_offset = lcm_not_zero(t->alignment_offset, alignment)
579 % max(t->physical_block_size, t->io_min);
581 /* Verify that new alignment_offset is on a logical block boundary */
582 if (t->alignment_offset & (t->logical_block_size - 1)) {
587 /* Discard alignment and granularity */
588 if (b->discard_granularity) {
589 alignment = queue_limit_discard_alignment(b, start);
591 if (t->discard_granularity != 0 &&
592 t->discard_alignment != alignment) {
593 top = t->discard_granularity + t->discard_alignment;
594 bottom = b->discard_granularity + alignment;
596 /* Verify that top and bottom intervals line up */
597 if ((max(top, bottom) % min(top, bottom)) != 0)
598 t->discard_misaligned = 1;
601 t->max_discard_sectors = min_not_zero(t->max_discard_sectors,
602 b->max_discard_sectors);
603 t->max_hw_discard_sectors = min_not_zero(t->max_hw_discard_sectors,
604 b->max_hw_discard_sectors);
605 t->discard_granularity = max(t->discard_granularity,
606 b->discard_granularity);
607 t->discard_alignment = lcm_not_zero(t->discard_alignment, alignment) %
608 t->discard_granularity;
611 if (b->chunk_sectors)
612 t->chunk_sectors = min_not_zero(t->chunk_sectors,
617 EXPORT_SYMBOL(blk_stack_limits);
620 * bdev_stack_limits - adjust queue limits for stacked drivers
621 * @t: the stacking driver limits (top device)
622 * @bdev: the component block_device (bottom)
623 * @start: first data sector within component device
626 * Merges queue limits for a top device and a block_device. Returns
627 * 0 if alignment didn't change. Returns -1 if adding the bottom
628 * device caused misalignment.
630 int bdev_stack_limits(struct queue_limits *t, struct block_device *bdev,
633 struct request_queue *bq = bdev_get_queue(bdev);
635 start += get_start_sect(bdev);
637 return blk_stack_limits(t, &bq->limits, start);
639 EXPORT_SYMBOL(bdev_stack_limits);
642 * disk_stack_limits - adjust queue limits for stacked drivers
643 * @disk: MD/DM gendisk (top)
644 * @bdev: the underlying block device (bottom)
645 * @offset: offset to beginning of data within component device
648 * Merges the limits for a top level gendisk and a bottom level
651 void disk_stack_limits(struct gendisk *disk, struct block_device *bdev,
654 struct request_queue *t = disk->queue;
656 if (bdev_stack_limits(&t->limits, bdev, offset >> 9) < 0) {
657 char top[BDEVNAME_SIZE], bottom[BDEVNAME_SIZE];
659 disk_name(disk, 0, top);
660 bdevname(bdev, bottom);
662 printk(KERN_NOTICE "%s: Warning: Device %s is misaligned\n",
666 EXPORT_SYMBOL(disk_stack_limits);
669 * blk_queue_dma_pad - set pad mask
670 * @q: the request queue for the device
675 * Appending pad buffer to a request modifies the last entry of a
676 * scatter list such that it includes the pad buffer.
678 void blk_queue_dma_pad(struct request_queue *q, unsigned int mask)
680 q->dma_pad_mask = mask;
682 EXPORT_SYMBOL(blk_queue_dma_pad);
685 * blk_queue_update_dma_pad - update pad mask
686 * @q: the request queue for the device
689 * Update dma pad mask.
691 * Appending pad buffer to a request modifies the last entry of a
692 * scatter list such that it includes the pad buffer.
694 void blk_queue_update_dma_pad(struct request_queue *q, unsigned int mask)
696 if (mask > q->dma_pad_mask)
697 q->dma_pad_mask = mask;
699 EXPORT_SYMBOL(blk_queue_update_dma_pad);
702 * blk_queue_dma_drain - Set up a drain buffer for excess dma.
703 * @q: the request queue for the device
704 * @dma_drain_needed: fn which returns non-zero if drain is necessary
705 * @buf: physically contiguous buffer
706 * @size: size of the buffer in bytes
708 * Some devices have excess DMA problems and can't simply discard (or
709 * zero fill) the unwanted piece of the transfer. They have to have a
710 * real area of memory to transfer it into. The use case for this is
711 * ATAPI devices in DMA mode. If the packet command causes a transfer
712 * bigger than the transfer size some HBAs will lock up if there
713 * aren't DMA elements to contain the excess transfer. What this API
714 * does is adjust the queue so that the buf is always appended
715 * silently to the scatterlist.
717 * Note: This routine adjusts max_hw_segments to make room for appending
718 * the drain buffer. If you call blk_queue_max_segments() after calling
719 * this routine, you must set the limit to one fewer than your device
720 * can support otherwise there won't be room for the drain buffer.
722 int blk_queue_dma_drain(struct request_queue *q,
723 dma_drain_needed_fn *dma_drain_needed,
724 void *buf, unsigned int size)
726 if (queue_max_segments(q) < 2)
728 /* make room for appending the drain */
729 blk_queue_max_segments(q, queue_max_segments(q) - 1);
730 q->dma_drain_needed = dma_drain_needed;
731 q->dma_drain_buffer = buf;
732 q->dma_drain_size = size;
736 EXPORT_SYMBOL_GPL(blk_queue_dma_drain);
739 * blk_queue_segment_boundary - set boundary rules for segment merging
740 * @q: the request queue for the device
741 * @mask: the memory boundary mask
743 void blk_queue_segment_boundary(struct request_queue *q, unsigned long mask)
745 if (mask < PAGE_SIZE - 1) {
746 mask = PAGE_SIZE - 1;
747 printk(KERN_INFO "%s: set to minimum %lx\n",
751 q->limits.seg_boundary_mask = mask;
753 EXPORT_SYMBOL(blk_queue_segment_boundary);
756 * blk_queue_virt_boundary - set boundary rules for bio merging
757 * @q: the request queue for the device
758 * @mask: the memory boundary mask
760 void blk_queue_virt_boundary(struct request_queue *q, unsigned long mask)
762 q->limits.virt_boundary_mask = mask;
764 EXPORT_SYMBOL(blk_queue_virt_boundary);
767 * blk_queue_dma_alignment - set dma length and memory alignment
768 * @q: the request queue for the device
769 * @mask: alignment mask
772 * set required memory and length alignment for direct dma transactions.
773 * this is used when building direct io requests for the queue.
776 void blk_queue_dma_alignment(struct request_queue *q, int mask)
778 q->dma_alignment = mask;
780 EXPORT_SYMBOL(blk_queue_dma_alignment);
783 * blk_queue_update_dma_alignment - update dma length and memory alignment
784 * @q: the request queue for the device
785 * @mask: alignment mask
788 * update required memory and length alignment for direct dma transactions.
789 * If the requested alignment is larger than the current alignment, then
790 * the current queue alignment is updated to the new value, otherwise it
791 * is left alone. The design of this is to allow multiple objects
792 * (driver, device, transport etc) to set their respective
793 * alignments without having them interfere.
796 void blk_queue_update_dma_alignment(struct request_queue *q, int mask)
798 BUG_ON(mask > PAGE_SIZE);
800 if (mask > q->dma_alignment)
801 q->dma_alignment = mask;
803 EXPORT_SYMBOL(blk_queue_update_dma_alignment);
805 void blk_queue_flush_queueable(struct request_queue *q, bool queueable)
808 blk_queue_flag_clear(QUEUE_FLAG_FLUSH_NQ, q);
810 blk_queue_flag_set(QUEUE_FLAG_FLUSH_NQ, q);
812 EXPORT_SYMBOL_GPL(blk_queue_flush_queueable);
815 * blk_set_queue_depth - tell the block layer about the device queue depth
816 * @q: the request queue for the device
817 * @depth: queue depth
820 void blk_set_queue_depth(struct request_queue *q, unsigned int depth)
822 q->queue_depth = depth;
823 wbt_set_queue_depth(q, depth);
825 EXPORT_SYMBOL(blk_set_queue_depth);
828 * blk_queue_write_cache - configure queue's write cache
829 * @q: the request queue for the device
830 * @wc: write back cache on or off
831 * @fua: device supports FUA writes, if true
833 * Tell the block layer about the write cache of @q.
835 void blk_queue_write_cache(struct request_queue *q, bool wc, bool fua)
838 blk_queue_flag_set(QUEUE_FLAG_WC, q);
840 blk_queue_flag_clear(QUEUE_FLAG_WC, q);
842 blk_queue_flag_set(QUEUE_FLAG_FUA, q);
844 blk_queue_flag_clear(QUEUE_FLAG_FUA, q);
846 wbt_set_write_cache(q, test_bit(QUEUE_FLAG_WC, &q->queue_flags));
848 EXPORT_SYMBOL_GPL(blk_queue_write_cache);
850 static int __init blk_settings_init(void)
852 blk_max_low_pfn = max_low_pfn - 1;
853 blk_max_pfn = max_pfn - 1;
856 subsys_initcall(blk_settings_init);