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_softirq_done(struct request_queue *q, softirq_done_fn *fn)
25 q->softirq_done_fn = fn;
27 EXPORT_SYMBOL(blk_queue_softirq_done);
29 void blk_queue_rq_timeout(struct request_queue *q, unsigned int timeout)
31 q->rq_timeout = timeout;
33 EXPORT_SYMBOL_GPL(blk_queue_rq_timeout);
35 void blk_queue_rq_timed_out(struct request_queue *q, rq_timed_out_fn *fn)
37 WARN_ON_ONCE(q->mq_ops);
38 q->rq_timed_out_fn = fn;
40 EXPORT_SYMBOL_GPL(blk_queue_rq_timed_out);
43 * blk_set_default_limits - reset limits to default values
44 * @lim: the queue_limits structure to reset
47 * Returns a queue_limit struct to its default state.
49 void blk_set_default_limits(struct queue_limits *lim)
51 lim->max_segments = BLK_MAX_SEGMENTS;
52 lim->max_discard_segments = 1;
53 lim->max_integrity_segments = 0;
54 lim->seg_boundary_mask = BLK_SEG_BOUNDARY_MASK;
55 lim->virt_boundary_mask = 0;
56 lim->max_segment_size = BLK_MAX_SEGMENT_SIZE;
57 lim->max_sectors = lim->max_hw_sectors = BLK_SAFE_MAX_SECTORS;
58 lim->max_dev_sectors = 0;
59 lim->chunk_sectors = 0;
60 lim->max_write_same_sectors = 0;
61 lim->max_write_zeroes_sectors = 0;
62 lim->max_discard_sectors = 0;
63 lim->max_hw_discard_sectors = 0;
64 lim->discard_granularity = 0;
65 lim->discard_alignment = 0;
66 lim->discard_misaligned = 0;
67 lim->logical_block_size = lim->physical_block_size = lim->io_min = 512;
68 lim->bounce_pfn = (unsigned long)(BLK_BOUNCE_ANY >> PAGE_SHIFT);
69 lim->alignment_offset = 0;
73 lim->zoned = BLK_ZONED_NONE;
75 EXPORT_SYMBOL(blk_set_default_limits);
78 * blk_set_stacking_limits - set default limits for stacking devices
79 * @lim: the queue_limits structure to reset
82 * Returns a queue_limit struct to its default state. Should be used
83 * by stacking drivers like DM that have no internal limits.
85 void blk_set_stacking_limits(struct queue_limits *lim)
87 blk_set_default_limits(lim);
89 /* Inherit limits from component devices */
90 lim->max_segments = USHRT_MAX;
91 lim->max_discard_segments = USHRT_MAX;
92 lim->max_hw_sectors = UINT_MAX;
93 lim->max_segment_size = UINT_MAX;
94 lim->max_sectors = UINT_MAX;
95 lim->max_dev_sectors = UINT_MAX;
96 lim->max_write_same_sectors = UINT_MAX;
97 lim->max_write_zeroes_sectors = UINT_MAX;
99 EXPORT_SYMBOL(blk_set_stacking_limits);
102 * blk_queue_make_request - define an alternate make_request function for a device
103 * @q: the request queue for the device to be affected
104 * @mfn: the alternate make_request function
107 * The normal way for &struct bios to be passed to a device
108 * driver is for them to be collected into requests on a request
109 * queue, and then to allow the device driver to select requests
110 * off that queue when it is ready. This works well for many block
111 * devices. However some block devices (typically virtual devices
112 * such as md or lvm) do not benefit from the processing on the
113 * request queue, and are served best by having the requests passed
114 * directly to them. This can be achieved by providing a function
115 * to blk_queue_make_request().
118 * The driver that does this *must* be able to deal appropriately
119 * with buffers in "highmemory". This can be accomplished by either calling
120 * kmap_atomic() to get a temporary kernel mapping, or by calling
121 * blk_queue_bounce() to create a buffer in normal memory.
123 void blk_queue_make_request(struct request_queue *q, make_request_fn *mfn)
128 q->nr_requests = BLKDEV_MAX_RQ;
130 q->make_request_fn = mfn;
131 blk_queue_dma_alignment(q, 511);
133 blk_set_default_limits(&q->limits);
135 EXPORT_SYMBOL(blk_queue_make_request);
138 * blk_queue_bounce_limit - set bounce buffer limit for queue
139 * @q: the request queue for the device
140 * @max_addr: the maximum address the device can handle
143 * Different hardware can have different requirements as to what pages
144 * it can do I/O directly to. A low level driver can call
145 * blk_queue_bounce_limit to have lower memory pages allocated as bounce
146 * buffers for doing I/O to pages residing above @max_addr.
148 void blk_queue_bounce_limit(struct request_queue *q, u64 max_addr)
150 unsigned long b_pfn = max_addr >> PAGE_SHIFT;
153 q->bounce_gfp = GFP_NOIO;
154 #if BITS_PER_LONG == 64
156 * Assume anything <= 4GB can be handled by IOMMU. Actually
157 * some IOMMUs can handle everything, but I don't know of a
158 * way to test this here.
160 if (b_pfn < (min_t(u64, 0xffffffffUL, BLK_BOUNCE_HIGH) >> PAGE_SHIFT))
162 q->limits.bounce_pfn = max(max_low_pfn, b_pfn);
164 if (b_pfn < blk_max_low_pfn)
166 q->limits.bounce_pfn = b_pfn;
169 init_emergency_isa_pool();
170 q->bounce_gfp = GFP_NOIO | GFP_DMA;
171 q->limits.bounce_pfn = b_pfn;
174 EXPORT_SYMBOL(blk_queue_bounce_limit);
177 * blk_queue_max_hw_sectors - set max sectors for a request for this queue
178 * @q: the request queue for the device
179 * @max_hw_sectors: max hardware sectors in the usual 512b unit
182 * Enables a low level driver to set a hard upper limit,
183 * max_hw_sectors, on the size of requests. max_hw_sectors is set by
184 * the device driver based upon the capabilities of the I/O
187 * max_dev_sectors is a hard limit imposed by the storage device for
188 * READ/WRITE requests. It is set by the disk driver.
190 * max_sectors is a soft limit imposed by the block layer for
191 * filesystem type requests. This value can be overridden on a
192 * per-device basis in /sys/block/<device>/queue/max_sectors_kb.
193 * The soft limit can not exceed max_hw_sectors.
195 void blk_queue_max_hw_sectors(struct request_queue *q, unsigned int max_hw_sectors)
197 struct queue_limits *limits = &q->limits;
198 unsigned int max_sectors;
200 if ((max_hw_sectors << 9) < PAGE_SIZE) {
201 max_hw_sectors = 1 << (PAGE_SHIFT - 9);
202 printk(KERN_INFO "%s: set to minimum %d\n",
203 __func__, max_hw_sectors);
206 limits->max_hw_sectors = max_hw_sectors;
207 max_sectors = min_not_zero(max_hw_sectors, limits->max_dev_sectors);
208 max_sectors = min_t(unsigned int, max_sectors, BLK_DEF_MAX_SECTORS);
209 limits->max_sectors = max_sectors;
210 q->backing_dev_info->io_pages = max_sectors >> (PAGE_SHIFT - 9);
212 EXPORT_SYMBOL(blk_queue_max_hw_sectors);
215 * blk_queue_chunk_sectors - set size of the chunk for this queue
216 * @q: the request queue for the device
217 * @chunk_sectors: chunk sectors in the usual 512b unit
220 * If a driver doesn't want IOs to cross a given chunk size, it can set
221 * this limit and prevent merging across chunks. Note that the chunk size
222 * must currently be a power-of-2 in sectors. Also note that the block
223 * layer must accept a page worth of data at any offset. So if the
224 * crossing of chunks is a hard limitation in the driver, it must still be
225 * prepared to split single page bios.
227 void blk_queue_chunk_sectors(struct request_queue *q, unsigned int chunk_sectors)
229 BUG_ON(!is_power_of_2(chunk_sectors));
230 q->limits.chunk_sectors = chunk_sectors;
232 EXPORT_SYMBOL(blk_queue_chunk_sectors);
235 * blk_queue_max_discard_sectors - set max sectors for a single discard
236 * @q: the request queue for the device
237 * @max_discard_sectors: maximum number of sectors to discard
239 void blk_queue_max_discard_sectors(struct request_queue *q,
240 unsigned int max_discard_sectors)
242 q->limits.max_hw_discard_sectors = max_discard_sectors;
243 q->limits.max_discard_sectors = max_discard_sectors;
245 EXPORT_SYMBOL(blk_queue_max_discard_sectors);
248 * blk_queue_max_write_same_sectors - set max sectors for a single write same
249 * @q: the request queue for the device
250 * @max_write_same_sectors: maximum number of sectors to write per command
252 void blk_queue_max_write_same_sectors(struct request_queue *q,
253 unsigned int max_write_same_sectors)
255 q->limits.max_write_same_sectors = max_write_same_sectors;
257 EXPORT_SYMBOL(blk_queue_max_write_same_sectors);
260 * blk_queue_max_write_zeroes_sectors - set max sectors for a single
262 * @q: the request queue for the device
263 * @max_write_zeroes_sectors: maximum number of sectors to write per command
265 void blk_queue_max_write_zeroes_sectors(struct request_queue *q,
266 unsigned int max_write_zeroes_sectors)
268 q->limits.max_write_zeroes_sectors = max_write_zeroes_sectors;
270 EXPORT_SYMBOL(blk_queue_max_write_zeroes_sectors);
273 * blk_queue_max_segments - set max hw segments for a request for this queue
274 * @q: the request queue for the device
275 * @max_segments: max number of segments
278 * Enables a low level driver to set an upper limit on the number of
279 * hw data segments in a request.
281 void blk_queue_max_segments(struct request_queue *q, unsigned short max_segments)
285 printk(KERN_INFO "%s: set to minimum %d\n",
286 __func__, max_segments);
289 q->limits.max_segments = max_segments;
291 EXPORT_SYMBOL(blk_queue_max_segments);
294 * blk_queue_max_discard_segments - set max segments for discard requests
295 * @q: the request queue for the device
296 * @max_segments: max number of segments
299 * Enables a low level driver to set an upper limit on the number of
300 * segments in a discard request.
302 void blk_queue_max_discard_segments(struct request_queue *q,
303 unsigned short max_segments)
305 q->limits.max_discard_segments = max_segments;
307 EXPORT_SYMBOL_GPL(blk_queue_max_discard_segments);
310 * blk_queue_max_segment_size - set max segment size for blk_rq_map_sg
311 * @q: the request queue for the device
312 * @max_size: max size of segment in bytes
315 * Enables a low level driver to set an upper limit on the size of a
318 void blk_queue_max_segment_size(struct request_queue *q, unsigned int max_size)
320 if (max_size < PAGE_SIZE) {
321 max_size = PAGE_SIZE;
322 printk(KERN_INFO "%s: set to minimum %d\n",
326 q->limits.max_segment_size = max_size;
328 EXPORT_SYMBOL(blk_queue_max_segment_size);
331 * blk_queue_logical_block_size - set logical block size for the queue
332 * @q: the request queue for the device
333 * @size: the logical block size, in bytes
336 * This should be set to the lowest possible block size that the
337 * storage device can address. The default of 512 covers most
340 void blk_queue_logical_block_size(struct request_queue *q, unsigned short size)
342 q->limits.logical_block_size = size;
344 if (q->limits.physical_block_size < size)
345 q->limits.physical_block_size = size;
347 if (q->limits.io_min < q->limits.physical_block_size)
348 q->limits.io_min = q->limits.physical_block_size;
350 EXPORT_SYMBOL(blk_queue_logical_block_size);
353 * blk_queue_physical_block_size - set physical block size for the queue
354 * @q: the request queue for the device
355 * @size: the physical block size, in bytes
358 * This should be set to the lowest possible sector size that the
359 * hardware can operate on without reverting to read-modify-write
362 void blk_queue_physical_block_size(struct request_queue *q, unsigned int size)
364 q->limits.physical_block_size = size;
366 if (q->limits.physical_block_size < q->limits.logical_block_size)
367 q->limits.physical_block_size = q->limits.logical_block_size;
369 if (q->limits.io_min < q->limits.physical_block_size)
370 q->limits.io_min = q->limits.physical_block_size;
372 EXPORT_SYMBOL(blk_queue_physical_block_size);
375 * blk_queue_alignment_offset - set physical block alignment offset
376 * @q: the request queue for the device
377 * @offset: alignment offset in bytes
380 * Some devices are naturally misaligned to compensate for things like
381 * the legacy DOS partition table 63-sector offset. Low-level drivers
382 * should call this function for devices whose first sector is not
385 void blk_queue_alignment_offset(struct request_queue *q, unsigned int offset)
387 q->limits.alignment_offset =
388 offset & (q->limits.physical_block_size - 1);
389 q->limits.misaligned = 0;
391 EXPORT_SYMBOL(blk_queue_alignment_offset);
394 * blk_limits_io_min - set minimum request size for a device
395 * @limits: the queue limits
396 * @min: smallest I/O size in bytes
399 * Some devices have an internal block size bigger than the reported
400 * hardware sector size. This function can be used to signal the
401 * smallest I/O the device can perform without incurring a performance
404 void blk_limits_io_min(struct queue_limits *limits, unsigned int min)
406 limits->io_min = min;
408 if (limits->io_min < limits->logical_block_size)
409 limits->io_min = limits->logical_block_size;
411 if (limits->io_min < limits->physical_block_size)
412 limits->io_min = limits->physical_block_size;
414 EXPORT_SYMBOL(blk_limits_io_min);
417 * blk_queue_io_min - set minimum request size for the queue
418 * @q: the request queue for the device
419 * @min: smallest I/O size in bytes
422 * Storage devices may report a granularity or preferred minimum I/O
423 * size which is the smallest request the device can perform without
424 * incurring a performance penalty. For disk drives this is often the
425 * physical block size. For RAID arrays it is often the stripe chunk
426 * size. A properly aligned multiple of minimum_io_size is the
427 * preferred request size for workloads where a high number of I/O
428 * operations is desired.
430 void blk_queue_io_min(struct request_queue *q, unsigned int min)
432 blk_limits_io_min(&q->limits, min);
434 EXPORT_SYMBOL(blk_queue_io_min);
437 * blk_limits_io_opt - set optimal request size for a device
438 * @limits: the queue limits
439 * @opt: smallest I/O size in bytes
442 * Storage devices may report an optimal I/O size, which is the
443 * device's preferred unit for sustained I/O. This is rarely reported
444 * for disk drives. For RAID arrays it is usually the stripe width or
445 * the internal track size. A properly aligned multiple of
446 * optimal_io_size is the preferred request size for workloads where
447 * sustained throughput is desired.
449 void blk_limits_io_opt(struct queue_limits *limits, unsigned int opt)
451 limits->io_opt = opt;
453 EXPORT_SYMBOL(blk_limits_io_opt);
456 * blk_queue_io_opt - set optimal request size for the queue
457 * @q: the request queue for the device
458 * @opt: optimal request size in bytes
461 * Storage devices may report an optimal I/O size, which is the
462 * device's preferred unit for sustained I/O. This is rarely reported
463 * for disk drives. For RAID arrays it is usually the stripe width or
464 * the internal track size. A properly aligned multiple of
465 * optimal_io_size is the preferred request size for workloads where
466 * sustained throughput is desired.
468 void blk_queue_io_opt(struct request_queue *q, unsigned int opt)
470 blk_limits_io_opt(&q->limits, opt);
472 EXPORT_SYMBOL(blk_queue_io_opt);
475 * blk_queue_stack_limits - inherit underlying queue limits for stacked drivers
476 * @t: the stacking driver (top)
477 * @b: the underlying device (bottom)
479 void blk_queue_stack_limits(struct request_queue *t, struct request_queue *b)
481 blk_stack_limits(&t->limits, &b->limits, 0);
483 EXPORT_SYMBOL(blk_queue_stack_limits);
486 * blk_stack_limits - adjust queue_limits for stacked devices
487 * @t: the stacking driver limits (top device)
488 * @b: the underlying queue limits (bottom, component device)
489 * @start: first data sector within component device
492 * This function is used by stacking drivers like MD and DM to ensure
493 * that all component devices have compatible block sizes and
494 * alignments. The stacking driver must provide a queue_limits
495 * struct (top) and then iteratively call the stacking function for
496 * all component (bottom) devices. The stacking function will
497 * attempt to combine the values and ensure proper alignment.
499 * Returns 0 if the top and bottom queue_limits are compatible. The
500 * top device's block sizes and alignment offsets may be adjusted to
501 * ensure alignment with the bottom device. If no compatible sizes
502 * and alignments exist, -1 is returned and the resulting top
503 * queue_limits will have the misaligned flag set to indicate that
504 * the alignment_offset is undefined.
506 int blk_stack_limits(struct queue_limits *t, struct queue_limits *b,
509 unsigned int top, bottom, alignment, ret = 0;
511 t->max_sectors = min_not_zero(t->max_sectors, b->max_sectors);
512 t->max_hw_sectors = min_not_zero(t->max_hw_sectors, b->max_hw_sectors);
513 t->max_dev_sectors = min_not_zero(t->max_dev_sectors, b->max_dev_sectors);
514 t->max_write_same_sectors = min(t->max_write_same_sectors,
515 b->max_write_same_sectors);
516 t->max_write_zeroes_sectors = min(t->max_write_zeroes_sectors,
517 b->max_write_zeroes_sectors);
518 t->bounce_pfn = min_not_zero(t->bounce_pfn, b->bounce_pfn);
520 t->seg_boundary_mask = min_not_zero(t->seg_boundary_mask,
521 b->seg_boundary_mask);
522 t->virt_boundary_mask = min_not_zero(t->virt_boundary_mask,
523 b->virt_boundary_mask);
525 t->max_segments = min_not_zero(t->max_segments, b->max_segments);
526 t->max_discard_segments = min_not_zero(t->max_discard_segments,
527 b->max_discard_segments);
528 t->max_integrity_segments = min_not_zero(t->max_integrity_segments,
529 b->max_integrity_segments);
531 t->max_segment_size = min_not_zero(t->max_segment_size,
532 b->max_segment_size);
534 t->misaligned |= b->misaligned;
536 alignment = queue_limit_alignment_offset(b, start);
538 /* Bottom device has different alignment. Check that it is
539 * compatible with the current top alignment.
541 if (t->alignment_offset != alignment) {
543 top = max(t->physical_block_size, t->io_min)
544 + t->alignment_offset;
545 bottom = max(b->physical_block_size, b->io_min) + alignment;
547 /* Verify that top and bottom intervals line up */
548 if (max(top, bottom) % min(top, bottom)) {
554 t->logical_block_size = max(t->logical_block_size,
555 b->logical_block_size);
557 t->physical_block_size = max(t->physical_block_size,
558 b->physical_block_size);
560 t->io_min = max(t->io_min, b->io_min);
561 t->io_opt = lcm_not_zero(t->io_opt, b->io_opt);
563 t->cluster &= b->cluster;
565 /* Physical block size a multiple of the logical block size? */
566 if (t->physical_block_size & (t->logical_block_size - 1)) {
567 t->physical_block_size = t->logical_block_size;
572 /* Minimum I/O a multiple of the physical block size? */
573 if (t->io_min & (t->physical_block_size - 1)) {
574 t->io_min = t->physical_block_size;
579 /* Optimal I/O a multiple of the physical block size? */
580 if (t->io_opt & (t->physical_block_size - 1)) {
586 t->raid_partial_stripes_expensive =
587 max(t->raid_partial_stripes_expensive,
588 b->raid_partial_stripes_expensive);
590 /* Find lowest common alignment_offset */
591 t->alignment_offset = lcm_not_zero(t->alignment_offset, alignment)
592 % max(t->physical_block_size, t->io_min);
594 /* Verify that new alignment_offset is on a logical block boundary */
595 if (t->alignment_offset & (t->logical_block_size - 1)) {
600 /* Discard alignment and granularity */
601 if (b->discard_granularity) {
602 alignment = queue_limit_discard_alignment(b, start);
604 if (t->discard_granularity != 0 &&
605 t->discard_alignment != alignment) {
606 top = t->discard_granularity + t->discard_alignment;
607 bottom = b->discard_granularity + alignment;
609 /* Verify that top and bottom intervals line up */
610 if ((max(top, bottom) % min(top, bottom)) != 0)
611 t->discard_misaligned = 1;
614 t->max_discard_sectors = min_not_zero(t->max_discard_sectors,
615 b->max_discard_sectors);
616 t->max_hw_discard_sectors = min_not_zero(t->max_hw_discard_sectors,
617 b->max_hw_discard_sectors);
618 t->discard_granularity = max(t->discard_granularity,
619 b->discard_granularity);
620 t->discard_alignment = lcm_not_zero(t->discard_alignment, alignment) %
621 t->discard_granularity;
624 if (b->chunk_sectors)
625 t->chunk_sectors = min_not_zero(t->chunk_sectors,
630 EXPORT_SYMBOL(blk_stack_limits);
633 * bdev_stack_limits - adjust queue limits for stacked drivers
634 * @t: the stacking driver limits (top device)
635 * @bdev: the component block_device (bottom)
636 * @start: first data sector within component device
639 * Merges queue limits for a top device and a block_device. Returns
640 * 0 if alignment didn't change. Returns -1 if adding the bottom
641 * device caused misalignment.
643 int bdev_stack_limits(struct queue_limits *t, struct block_device *bdev,
646 struct request_queue *bq = bdev_get_queue(bdev);
648 start += get_start_sect(bdev);
650 return blk_stack_limits(t, &bq->limits, start);
652 EXPORT_SYMBOL(bdev_stack_limits);
655 * disk_stack_limits - adjust queue limits for stacked drivers
656 * @disk: MD/DM gendisk (top)
657 * @bdev: the underlying block device (bottom)
658 * @offset: offset to beginning of data within component device
661 * Merges the limits for a top level gendisk and a bottom level
664 void disk_stack_limits(struct gendisk *disk, struct block_device *bdev,
667 struct request_queue *t = disk->queue;
669 if (bdev_stack_limits(&t->limits, bdev, offset >> 9) < 0) {
670 char top[BDEVNAME_SIZE], bottom[BDEVNAME_SIZE];
672 disk_name(disk, 0, top);
673 bdevname(bdev, bottom);
675 printk(KERN_NOTICE "%s: Warning: Device %s is misaligned\n",
679 EXPORT_SYMBOL(disk_stack_limits);
682 * blk_queue_dma_pad - set pad mask
683 * @q: the request queue for the device
688 * Appending pad buffer to a request modifies the last entry of a
689 * scatter list such that it includes the pad buffer.
691 void blk_queue_dma_pad(struct request_queue *q, unsigned int mask)
693 q->dma_pad_mask = mask;
695 EXPORT_SYMBOL(blk_queue_dma_pad);
698 * blk_queue_update_dma_pad - update pad mask
699 * @q: the request queue for the device
702 * Update dma pad mask.
704 * Appending pad buffer to a request modifies the last entry of a
705 * scatter list such that it includes the pad buffer.
707 void blk_queue_update_dma_pad(struct request_queue *q, unsigned int mask)
709 if (mask > q->dma_pad_mask)
710 q->dma_pad_mask = mask;
712 EXPORT_SYMBOL(blk_queue_update_dma_pad);
715 * blk_queue_dma_drain - Set up a drain buffer for excess dma.
716 * @q: the request queue for the device
717 * @dma_drain_needed: fn which returns non-zero if drain is necessary
718 * @buf: physically contiguous buffer
719 * @size: size of the buffer in bytes
721 * Some devices have excess DMA problems and can't simply discard (or
722 * zero fill) the unwanted piece of the transfer. They have to have a
723 * real area of memory to transfer it into. The use case for this is
724 * ATAPI devices in DMA mode. If the packet command causes a transfer
725 * bigger than the transfer size some HBAs will lock up if there
726 * aren't DMA elements to contain the excess transfer. What this API
727 * does is adjust the queue so that the buf is always appended
728 * silently to the scatterlist.
730 * Note: This routine adjusts max_hw_segments to make room for appending
731 * the drain buffer. If you call blk_queue_max_segments() after calling
732 * this routine, you must set the limit to one fewer than your device
733 * can support otherwise there won't be room for the drain buffer.
735 int blk_queue_dma_drain(struct request_queue *q,
736 dma_drain_needed_fn *dma_drain_needed,
737 void *buf, unsigned int size)
739 if (queue_max_segments(q) < 2)
741 /* make room for appending the drain */
742 blk_queue_max_segments(q, queue_max_segments(q) - 1);
743 q->dma_drain_needed = dma_drain_needed;
744 q->dma_drain_buffer = buf;
745 q->dma_drain_size = size;
749 EXPORT_SYMBOL_GPL(blk_queue_dma_drain);
752 * blk_queue_segment_boundary - set boundary rules for segment merging
753 * @q: the request queue for the device
754 * @mask: the memory boundary mask
756 void blk_queue_segment_boundary(struct request_queue *q, unsigned long mask)
758 if (mask < PAGE_SIZE - 1) {
759 mask = PAGE_SIZE - 1;
760 printk(KERN_INFO "%s: set to minimum %lx\n",
764 q->limits.seg_boundary_mask = mask;
766 EXPORT_SYMBOL(blk_queue_segment_boundary);
769 * blk_queue_virt_boundary - set boundary rules for bio merging
770 * @q: the request queue for the device
771 * @mask: the memory boundary mask
773 void blk_queue_virt_boundary(struct request_queue *q, unsigned long mask)
775 q->limits.virt_boundary_mask = mask;
777 EXPORT_SYMBOL(blk_queue_virt_boundary);
780 * blk_queue_dma_alignment - set dma length and memory alignment
781 * @q: the request queue for the device
782 * @mask: alignment mask
785 * set required memory and length alignment for direct dma transactions.
786 * this is used when building direct io requests for the queue.
789 void blk_queue_dma_alignment(struct request_queue *q, int mask)
791 q->dma_alignment = mask;
793 EXPORT_SYMBOL(blk_queue_dma_alignment);
796 * blk_queue_update_dma_alignment - update dma length and memory alignment
797 * @q: the request queue for the device
798 * @mask: alignment mask
801 * update required memory and length alignment for direct dma transactions.
802 * If the requested alignment is larger than the current alignment, then
803 * the current queue alignment is updated to the new value, otherwise it
804 * is left alone. The design of this is to allow multiple objects
805 * (driver, device, transport etc) to set their respective
806 * alignments without having them interfere.
809 void blk_queue_update_dma_alignment(struct request_queue *q, int mask)
811 BUG_ON(mask > PAGE_SIZE);
813 if (mask > q->dma_alignment)
814 q->dma_alignment = mask;
816 EXPORT_SYMBOL(blk_queue_update_dma_alignment);
818 void blk_queue_flush_queueable(struct request_queue *q, bool queueable)
821 blk_queue_flag_clear(QUEUE_FLAG_FLUSH_NQ, q);
823 blk_queue_flag_set(QUEUE_FLAG_FLUSH_NQ, q);
825 EXPORT_SYMBOL_GPL(blk_queue_flush_queueable);
828 * blk_set_queue_depth - tell the block layer about the device queue depth
829 * @q: the request queue for the device
830 * @depth: queue depth
833 void blk_set_queue_depth(struct request_queue *q, unsigned int depth)
835 q->queue_depth = depth;
836 wbt_set_queue_depth(q, depth);
838 EXPORT_SYMBOL(blk_set_queue_depth);
841 * blk_queue_write_cache - configure queue's write cache
842 * @q: the request queue for the device
843 * @wc: write back cache on or off
844 * @fua: device supports FUA writes, if true
846 * Tell the block layer about the write cache of @q.
848 void blk_queue_write_cache(struct request_queue *q, bool wc, bool fua)
850 spin_lock_irq(q->queue_lock);
852 queue_flag_set(QUEUE_FLAG_WC, q);
854 queue_flag_clear(QUEUE_FLAG_WC, q);
856 queue_flag_set(QUEUE_FLAG_FUA, q);
858 queue_flag_clear(QUEUE_FLAG_FUA, q);
859 spin_unlock_irq(q->queue_lock);
861 wbt_set_write_cache(q, test_bit(QUEUE_FLAG_WC, &q->queue_flags));
863 EXPORT_SYMBOL_GPL(blk_queue_write_cache);
865 static int __init blk_settings_init(void)
867 blk_max_low_pfn = max_low_pfn - 1;
868 blk_max_pfn = max_pfn - 1;
871 subsys_initcall(blk_settings_init);