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/bootmem.h> /* for max_pfn/max_low_pfn */
10 #include <linux/gcd.h>
11 #include <linux/lcm.h>
15 unsigned long blk_max_low_pfn
;
16 EXPORT_SYMBOL(blk_max_low_pfn
);
18 unsigned long blk_max_pfn
;
21 * blk_queue_prep_rq - set a prepare_request function for queue
23 * @pfn: prepare_request function
25 * It's possible for a queue to register a prepare_request callback which
26 * is invoked before the request is handed to the request_fn. The goal of
27 * the function is to prepare a request for I/O, it can be used to build a
28 * cdb from the request data for instance.
31 void blk_queue_prep_rq(struct request_queue
*q
, prep_rq_fn
*pfn
)
35 EXPORT_SYMBOL(blk_queue_prep_rq
);
38 * blk_queue_merge_bvec - set a merge_bvec function for queue
40 * @mbfn: merge_bvec_fn
42 * Usually queues have static limitations on the max sectors or segments that
43 * we can put in a request. Stacking drivers may have some settings that
44 * are dynamic, and thus we have to query the queue whether it is ok to
45 * add a new bio_vec to a bio at a given offset or not. If the block device
46 * has such limitations, it needs to register a merge_bvec_fn to control
47 * the size of bio's sent to it. Note that a block device *must* allow a
48 * single page to be added to an empty bio. The block device driver may want
49 * to use the bio_split() function to deal with these bio's. By default
50 * no merge_bvec_fn is defined for a queue, and only the fixed limits are
53 void blk_queue_merge_bvec(struct request_queue
*q
, merge_bvec_fn
*mbfn
)
55 q
->merge_bvec_fn
= mbfn
;
57 EXPORT_SYMBOL(blk_queue_merge_bvec
);
59 void blk_queue_softirq_done(struct request_queue
*q
, softirq_done_fn
*fn
)
61 q
->softirq_done_fn
= fn
;
63 EXPORT_SYMBOL(blk_queue_softirq_done
);
65 void blk_queue_rq_timeout(struct request_queue
*q
, unsigned int timeout
)
67 q
->rq_timeout
= timeout
;
69 EXPORT_SYMBOL_GPL(blk_queue_rq_timeout
);
71 void blk_queue_rq_timed_out(struct request_queue
*q
, rq_timed_out_fn
*fn
)
73 q
->rq_timed_out_fn
= fn
;
75 EXPORT_SYMBOL_GPL(blk_queue_rq_timed_out
);
77 void blk_queue_lld_busy(struct request_queue
*q
, lld_busy_fn
*fn
)
81 EXPORT_SYMBOL_GPL(blk_queue_lld_busy
);
84 * blk_set_default_limits - reset limits to default values
85 * @lim: the queue_limits structure to reset
88 * Returns a queue_limit struct to its default state. Can be used by
89 * stacking drivers like DM that stage table swaps and reuse an
90 * existing device queue.
92 void blk_set_default_limits(struct queue_limits
*lim
)
94 lim
->max_phys_segments
= MAX_PHYS_SEGMENTS
;
95 lim
->max_hw_segments
= MAX_HW_SEGMENTS
;
96 lim
->seg_boundary_mask
= BLK_SEG_BOUNDARY_MASK
;
97 lim
->max_segment_size
= MAX_SEGMENT_SIZE
;
98 lim
->max_sectors
= BLK_DEF_MAX_SECTORS
;
99 lim
->max_hw_sectors
= INT_MAX
;
100 lim
->max_discard_sectors
= SAFE_MAX_SECTORS
;
101 lim
->logical_block_size
= lim
->physical_block_size
= lim
->io_min
= 512;
102 lim
->bounce_pfn
= (unsigned long)(BLK_BOUNCE_ANY
>> PAGE_SHIFT
);
103 lim
->alignment_offset
= 0;
108 EXPORT_SYMBOL(blk_set_default_limits
);
111 * blk_queue_make_request - define an alternate make_request function for a device
112 * @q: the request queue for the device to be affected
113 * @mfn: the alternate make_request function
116 * The normal way for &struct bios to be passed to a device
117 * driver is for them to be collected into requests on a request
118 * queue, and then to allow the device driver to select requests
119 * off that queue when it is ready. This works well for many block
120 * devices. However some block devices (typically virtual devices
121 * such as md or lvm) do not benefit from the processing on the
122 * request queue, and are served best by having the requests passed
123 * directly to them. This can be achieved by providing a function
124 * to blk_queue_make_request().
127 * The driver that does this *must* be able to deal appropriately
128 * with buffers in "highmemory". This can be accomplished by either calling
129 * __bio_kmap_atomic() to get a temporary kernel mapping, or by calling
130 * blk_queue_bounce() to create a buffer in normal memory.
132 void blk_queue_make_request(struct request_queue
*q
, make_request_fn
*mfn
)
137 q
->nr_requests
= BLKDEV_MAX_RQ
;
139 q
->make_request_fn
= mfn
;
140 blk_queue_dma_alignment(q
, 511);
141 blk_queue_congestion_threshold(q
);
142 q
->nr_batching
= BLK_BATCH_REQ
;
144 q
->unplug_thresh
= 4; /* hmm */
145 q
->unplug_delay
= (3 * HZ
) / 1000; /* 3 milliseconds */
146 if (q
->unplug_delay
== 0)
149 q
->unplug_timer
.function
= blk_unplug_timeout
;
150 q
->unplug_timer
.data
= (unsigned long)q
;
152 blk_set_default_limits(&q
->limits
);
153 blk_queue_max_sectors(q
, SAFE_MAX_SECTORS
);
156 * If the caller didn't supply a lock, fall back to our embedded
160 q
->queue_lock
= &q
->__queue_lock
;
163 * by default assume old behaviour and bounce for any highmem page
165 blk_queue_bounce_limit(q
, BLK_BOUNCE_HIGH
);
167 EXPORT_SYMBOL(blk_queue_make_request
);
170 * blk_queue_bounce_limit - set bounce buffer limit for queue
171 * @q: the request queue for the device
172 * @dma_mask: the maximum address the device can handle
175 * Different hardware can have different requirements as to what pages
176 * it can do I/O directly to. A low level driver can call
177 * blk_queue_bounce_limit to have lower memory pages allocated as bounce
178 * buffers for doing I/O to pages residing above @dma_mask.
180 void blk_queue_bounce_limit(struct request_queue
*q
, u64 dma_mask
)
182 unsigned long b_pfn
= dma_mask
>> PAGE_SHIFT
;
185 q
->bounce_gfp
= GFP_NOIO
;
186 #if BITS_PER_LONG == 64
188 * Assume anything <= 4GB can be handled by IOMMU. Actually
189 * some IOMMUs can handle everything, but I don't know of a
190 * way to test this here.
192 if (b_pfn
< (min_t(u64
, 0xffffffffUL
, BLK_BOUNCE_HIGH
) >> PAGE_SHIFT
))
194 q
->limits
.bounce_pfn
= max_low_pfn
;
196 if (b_pfn
< blk_max_low_pfn
)
198 q
->limits
.bounce_pfn
= b_pfn
;
201 init_emergency_isa_pool();
202 q
->bounce_gfp
= GFP_NOIO
| GFP_DMA
;
203 q
->limits
.bounce_pfn
= b_pfn
;
206 EXPORT_SYMBOL(blk_queue_bounce_limit
);
209 * blk_queue_max_sectors - set max sectors for a request for this queue
210 * @q: the request queue for the device
211 * @max_sectors: max sectors in the usual 512b unit
214 * Enables a low level driver to set an upper limit on the size of
217 void blk_queue_max_sectors(struct request_queue
*q
, unsigned int max_sectors
)
219 if ((max_sectors
<< 9) < PAGE_CACHE_SIZE
) {
220 max_sectors
= 1 << (PAGE_CACHE_SHIFT
- 9);
221 printk(KERN_INFO
"%s: set to minimum %d\n",
222 __func__
, max_sectors
);
225 if (BLK_DEF_MAX_SECTORS
> max_sectors
)
226 q
->limits
.max_hw_sectors
= q
->limits
.max_sectors
= max_sectors
;
228 q
->limits
.max_sectors
= BLK_DEF_MAX_SECTORS
;
229 q
->limits
.max_hw_sectors
= max_sectors
;
232 EXPORT_SYMBOL(blk_queue_max_sectors
);
234 void blk_queue_max_hw_sectors(struct request_queue
*q
, unsigned int max_sectors
)
236 if (BLK_DEF_MAX_SECTORS
> max_sectors
)
237 q
->limits
.max_hw_sectors
= BLK_DEF_MAX_SECTORS
;
239 q
->limits
.max_hw_sectors
= max_sectors
;
241 EXPORT_SYMBOL(blk_queue_max_hw_sectors
);
244 * blk_queue_max_discard_sectors - set max sectors for a single discard
245 * @q: the request queue for the device
246 * @max_discard_sectors: maximum number of sectors to discard
248 void blk_queue_max_discard_sectors(struct request_queue
*q
,
249 unsigned int max_discard_sectors
)
251 q
->limits
.max_discard_sectors
= max_discard_sectors
;
253 EXPORT_SYMBOL(blk_queue_max_discard_sectors
);
256 * blk_queue_max_phys_segments - set max phys segments for a request for this queue
257 * @q: the request queue for the device
258 * @max_segments: max number of segments
261 * Enables a low level driver to set an upper limit on the number of
262 * physical data segments in a request. This would be the largest sized
263 * scatter list the driver could handle.
265 void blk_queue_max_phys_segments(struct request_queue
*q
,
266 unsigned short max_segments
)
270 printk(KERN_INFO
"%s: set to minimum %d\n",
271 __func__
, max_segments
);
274 q
->limits
.max_phys_segments
= max_segments
;
276 EXPORT_SYMBOL(blk_queue_max_phys_segments
);
279 * blk_queue_max_hw_segments - set max hw segments for a request for this queue
280 * @q: the request queue for the device
281 * @max_segments: max number of segments
284 * Enables a low level driver to set an upper limit on the number of
285 * hw data segments in a request. This would be the largest number of
286 * address/length pairs the host adapter can actually give at once
289 void blk_queue_max_hw_segments(struct request_queue
*q
,
290 unsigned short max_segments
)
294 printk(KERN_INFO
"%s: set to minimum %d\n",
295 __func__
, max_segments
);
298 q
->limits
.max_hw_segments
= max_segments
;
300 EXPORT_SYMBOL(blk_queue_max_hw_segments
);
303 * blk_queue_max_segment_size - set max segment size for blk_rq_map_sg
304 * @q: the request queue for the device
305 * @max_size: max size of segment in bytes
308 * Enables a low level driver to set an upper limit on the size of a
311 void blk_queue_max_segment_size(struct request_queue
*q
, unsigned int max_size
)
313 if (max_size
< PAGE_CACHE_SIZE
) {
314 max_size
= PAGE_CACHE_SIZE
;
315 printk(KERN_INFO
"%s: set to minimum %d\n",
319 q
->limits
.max_segment_size
= max_size
;
321 EXPORT_SYMBOL(blk_queue_max_segment_size
);
324 * blk_queue_logical_block_size - set logical block size for the queue
325 * @q: the request queue for the device
326 * @size: the logical block size, in bytes
329 * This should be set to the lowest possible block size that the
330 * storage device can address. The default of 512 covers most
333 void blk_queue_logical_block_size(struct request_queue
*q
, unsigned short size
)
335 q
->limits
.logical_block_size
= size
;
337 if (q
->limits
.physical_block_size
< size
)
338 q
->limits
.physical_block_size
= size
;
340 if (q
->limits
.io_min
< q
->limits
.physical_block_size
)
341 q
->limits
.io_min
= q
->limits
.physical_block_size
;
343 EXPORT_SYMBOL(blk_queue_logical_block_size
);
346 * blk_queue_physical_block_size - set physical block size for the queue
347 * @q: the request queue for the device
348 * @size: the physical block size, in bytes
351 * This should be set to the lowest possible sector size that the
352 * hardware can operate on without reverting to read-modify-write
355 void blk_queue_physical_block_size(struct request_queue
*q
, unsigned int size
)
357 q
->limits
.physical_block_size
= size
;
359 if (q
->limits
.physical_block_size
< q
->limits
.logical_block_size
)
360 q
->limits
.physical_block_size
= q
->limits
.logical_block_size
;
362 if (q
->limits
.io_min
< q
->limits
.physical_block_size
)
363 q
->limits
.io_min
= q
->limits
.physical_block_size
;
365 EXPORT_SYMBOL(blk_queue_physical_block_size
);
368 * blk_queue_alignment_offset - set physical block alignment offset
369 * @q: the request queue for the device
370 * @offset: alignment offset in bytes
373 * Some devices are naturally misaligned to compensate for things like
374 * the legacy DOS partition table 63-sector offset. Low-level drivers
375 * should call this function for devices whose first sector is not
378 void blk_queue_alignment_offset(struct request_queue
*q
, unsigned int offset
)
380 q
->limits
.alignment_offset
=
381 offset
& (q
->limits
.physical_block_size
- 1);
382 q
->limits
.misaligned
= 0;
384 EXPORT_SYMBOL(blk_queue_alignment_offset
);
387 * blk_limits_io_min - set minimum request size for a device
388 * @limits: the queue limits
389 * @min: smallest I/O size in bytes
392 * Some devices have an internal block size bigger than the reported
393 * hardware sector size. This function can be used to signal the
394 * smallest I/O the device can perform without incurring a performance
397 void blk_limits_io_min(struct queue_limits
*limits
, unsigned int min
)
399 limits
->io_min
= min
;
401 if (limits
->io_min
< limits
->logical_block_size
)
402 limits
->io_min
= limits
->logical_block_size
;
404 if (limits
->io_min
< limits
->physical_block_size
)
405 limits
->io_min
= limits
->physical_block_size
;
407 EXPORT_SYMBOL(blk_limits_io_min
);
410 * blk_queue_io_min - set minimum request size for the queue
411 * @q: the request queue for the device
412 * @min: smallest I/O size in bytes
415 * Storage devices may report a granularity or preferred minimum I/O
416 * size which is the smallest request the device can perform without
417 * incurring a performance penalty. For disk drives this is often the
418 * physical block size. For RAID arrays it is often the stripe chunk
419 * size. A properly aligned multiple of minimum_io_size is the
420 * preferred request size for workloads where a high number of I/O
421 * operations is desired.
423 void blk_queue_io_min(struct request_queue
*q
, unsigned int min
)
425 blk_limits_io_min(&q
->limits
, min
);
427 EXPORT_SYMBOL(blk_queue_io_min
);
430 * blk_limits_io_opt - set optimal request size for a device
431 * @limits: the queue limits
432 * @opt: smallest I/O size in bytes
435 * Storage devices may report an optimal I/O size, which is the
436 * device's preferred unit for sustained I/O. This is rarely reported
437 * for disk drives. For RAID arrays it is usually the stripe width or
438 * the internal track size. A properly aligned multiple of
439 * optimal_io_size is the preferred request size for workloads where
440 * sustained throughput is desired.
442 void blk_limits_io_opt(struct queue_limits
*limits
, unsigned int opt
)
444 limits
->io_opt
= opt
;
446 EXPORT_SYMBOL(blk_limits_io_opt
);
449 * blk_queue_io_opt - set optimal request size for the queue
450 * @q: the request queue for the device
451 * @opt: optimal request size in bytes
454 * Storage devices may report an optimal I/O size, which is the
455 * device's preferred unit for sustained I/O. This is rarely reported
456 * for disk drives. For RAID arrays it is usually the stripe width or
457 * the internal track size. A properly aligned multiple of
458 * optimal_io_size is the preferred request size for workloads where
459 * sustained throughput is desired.
461 void blk_queue_io_opt(struct request_queue
*q
, unsigned int opt
)
463 blk_limits_io_opt(&q
->limits
, opt
);
465 EXPORT_SYMBOL(blk_queue_io_opt
);
468 * Returns the minimum that is _not_ zero, unless both are zero.
470 #define min_not_zero(l, r) (l == 0) ? r : ((r == 0) ? l : min(l, r))
473 * blk_queue_stack_limits - inherit underlying queue limits for stacked drivers
474 * @t: the stacking driver (top)
475 * @b: the underlying device (bottom)
477 void blk_queue_stack_limits(struct request_queue
*t
, struct request_queue
*b
)
479 blk_stack_limits(&t
->limits
, &b
->limits
, 0);
483 else if (!test_bit(QUEUE_FLAG_CLUSTER
, &b
->queue_flags
)) {
485 spin_lock_irqsave(t
->queue_lock
, flags
);
486 queue_flag_clear(QUEUE_FLAG_CLUSTER
, t
);
487 spin_unlock_irqrestore(t
->queue_lock
, flags
);
490 EXPORT_SYMBOL(blk_queue_stack_limits
);
493 * blk_stack_limits - adjust queue_limits for stacked devices
494 * @t: the stacking driver limits (top device)
495 * @b: the underlying queue limits (bottom, component device)
496 * @offset: offset to beginning of data within component device
499 * This function is used by stacking drivers like MD and DM to ensure
500 * that all component devices have compatible block sizes and
501 * alignments. The stacking driver must provide a queue_limits
502 * struct (top) and then iteratively call the stacking function for
503 * all component (bottom) devices. The stacking function will
504 * attempt to combine the values and ensure proper alignment.
506 * Returns 0 if the top and bottom queue_limits are compatible. The
507 * top device's block sizes and alignment offsets may be adjusted to
508 * ensure alignment with the bottom device. If no compatible sizes
509 * and alignments exist, -1 is returned and the resulting top
510 * queue_limits will have the misaligned flag set to indicate that
511 * the alignment_offset is undefined.
513 int blk_stack_limits(struct queue_limits
*t
, struct queue_limits
*b
,
517 unsigned int top
, bottom
, ret
= 0;
519 t
->max_sectors
= min_not_zero(t
->max_sectors
, b
->max_sectors
);
520 t
->max_hw_sectors
= min_not_zero(t
->max_hw_sectors
, b
->max_hw_sectors
);
521 t
->bounce_pfn
= min_not_zero(t
->bounce_pfn
, b
->bounce_pfn
);
523 t
->seg_boundary_mask
= min_not_zero(t
->seg_boundary_mask
,
524 b
->seg_boundary_mask
);
526 t
->max_phys_segments
= min_not_zero(t
->max_phys_segments
,
527 b
->max_phys_segments
);
529 t
->max_hw_segments
= min_not_zero(t
->max_hw_segments
,
532 t
->max_segment_size
= min_not_zero(t
->max_segment_size
,
533 b
->max_segment_size
);
535 t
->misaligned
|= b
->misaligned
;
537 alignment
= queue_limit_alignment_offset(b
, offset
);
539 /* Bottom device has different alignment. Check that it is
540 * compatible with the current top alignment.
542 if (t
->alignment_offset
!= alignment
) {
544 top
= max(t
->physical_block_size
, t
->io_min
)
545 + t
->alignment_offset
;
546 bottom
= max(b
->physical_block_size
, b
->io_min
) + alignment
;
548 /* Verify that top and bottom intervals line up */
549 if (max(top
, bottom
) & (min(top
, bottom
) - 1)) {
555 t
->logical_block_size
= max(t
->logical_block_size
,
556 b
->logical_block_size
);
558 t
->physical_block_size
= max(t
->physical_block_size
,
559 b
->physical_block_size
);
561 t
->io_min
= max(t
->io_min
, b
->io_min
);
562 t
->io_opt
= lcm(t
->io_opt
, b
->io_opt
);
564 t
->no_cluster
|= b
->no_cluster
;
566 /* Physical block size a multiple of the logical block size? */
567 if (t
->physical_block_size
& (t
->logical_block_size
- 1)) {
568 t
->physical_block_size
= t
->logical_block_size
;
573 /* Minimum I/O a multiple of the physical block size? */
574 if (t
->io_min
& (t
->physical_block_size
- 1)) {
575 t
->io_min
= t
->physical_block_size
;
580 /* Optimal I/O a multiple of the physical block size? */
581 if (t
->io_opt
& (t
->physical_block_size
- 1)) {
587 /* Find lowest common alignment_offset */
588 t
->alignment_offset
= lcm(t
->alignment_offset
, alignment
)
589 & (max(t
->physical_block_size
, t
->io_min
) - 1);
591 /* Verify that new alignment_offset is on a logical block boundary */
592 if (t
->alignment_offset
& (t
->logical_block_size
- 1)) {
598 t
->max_discard_sectors
= min_not_zero(t
->max_discard_sectors
,
599 b
->max_discard_sectors
);
603 EXPORT_SYMBOL(blk_stack_limits
);
606 * bdev_stack_limits - adjust queue limits for stacked drivers
607 * @t: the stacking driver limits (top device)
608 * @bdev: the component block_device (bottom)
609 * @start: first data sector within component device
612 * Merges queue limits for a top device and a block_device. Returns
613 * 0 if alignment didn't change. Returns -1 if adding the bottom
614 * device caused misalignment.
616 int bdev_stack_limits(struct queue_limits
*t
, struct block_device
*bdev
,
619 struct request_queue
*bq
= bdev_get_queue(bdev
);
621 start
+= get_start_sect(bdev
);
623 return blk_stack_limits(t
, &bq
->limits
, start
<< 9);
625 EXPORT_SYMBOL(bdev_stack_limits
);
628 * disk_stack_limits - adjust queue limits for stacked drivers
629 * @disk: MD/DM gendisk (top)
630 * @bdev: the underlying block device (bottom)
631 * @offset: offset to beginning of data within component device
634 * Merges the limits for two queues. Returns 0 if alignment
635 * didn't change. Returns -1 if adding the bottom device caused
638 void disk_stack_limits(struct gendisk
*disk
, struct block_device
*bdev
,
641 struct request_queue
*t
= disk
->queue
;
642 struct request_queue
*b
= bdev_get_queue(bdev
);
644 offset
+= get_start_sect(bdev
) << 9;
646 if (blk_stack_limits(&t
->limits
, &b
->limits
, offset
) < 0) {
647 char top
[BDEVNAME_SIZE
], bottom
[BDEVNAME_SIZE
];
649 disk_name(disk
, 0, top
);
650 bdevname(bdev
, bottom
);
652 printk(KERN_NOTICE
"%s: Warning: Device %s is misaligned\n",
658 else if (!test_bit(QUEUE_FLAG_CLUSTER
, &b
->queue_flags
)) {
661 spin_lock_irqsave(t
->queue_lock
, flags
);
662 if (!test_bit(QUEUE_FLAG_CLUSTER
, &b
->queue_flags
))
663 queue_flag_clear(QUEUE_FLAG_CLUSTER
, t
);
664 spin_unlock_irqrestore(t
->queue_lock
, flags
);
667 EXPORT_SYMBOL(disk_stack_limits
);
670 * blk_queue_dma_pad - set pad mask
671 * @q: the request queue for the device
676 * Appending pad buffer to a request modifies the last entry of a
677 * scatter list such that it includes the pad buffer.
679 void blk_queue_dma_pad(struct request_queue
*q
, unsigned int mask
)
681 q
->dma_pad_mask
= mask
;
683 EXPORT_SYMBOL(blk_queue_dma_pad
);
686 * blk_queue_update_dma_pad - update pad mask
687 * @q: the request queue for the device
690 * Update dma pad mask.
692 * Appending pad buffer to a request modifies the last entry of a
693 * scatter list such that it includes the pad buffer.
695 void blk_queue_update_dma_pad(struct request_queue
*q
, unsigned int mask
)
697 if (mask
> q
->dma_pad_mask
)
698 q
->dma_pad_mask
= mask
;
700 EXPORT_SYMBOL(blk_queue_update_dma_pad
);
703 * blk_queue_dma_drain - Set up a drain buffer for excess dma.
704 * @q: the request queue for the device
705 * @dma_drain_needed: fn which returns non-zero if drain is necessary
706 * @buf: physically contiguous buffer
707 * @size: size of the buffer in bytes
709 * Some devices have excess DMA problems and can't simply discard (or
710 * zero fill) the unwanted piece of the transfer. They have to have a
711 * real area of memory to transfer it into. The use case for this is
712 * ATAPI devices in DMA mode. If the packet command causes a transfer
713 * bigger than the transfer size some HBAs will lock up if there
714 * aren't DMA elements to contain the excess transfer. What this API
715 * does is adjust the queue so that the buf is always appended
716 * silently to the scatterlist.
718 * Note: This routine adjusts max_hw_segments to make room for
719 * appending the drain buffer. If you call
720 * blk_queue_max_hw_segments() or blk_queue_max_phys_segments() after
721 * calling this routine, you must set the limit to one fewer than your
722 * device can support otherwise there won't be room for the drain
725 int blk_queue_dma_drain(struct request_queue
*q
,
726 dma_drain_needed_fn
*dma_drain_needed
,
727 void *buf
, unsigned int size
)
729 if (queue_max_hw_segments(q
) < 2 || queue_max_phys_segments(q
) < 2)
731 /* make room for appending the drain */
732 blk_queue_max_hw_segments(q
, queue_max_hw_segments(q
) - 1);
733 blk_queue_max_phys_segments(q
, queue_max_phys_segments(q
) - 1);
734 q
->dma_drain_needed
= dma_drain_needed
;
735 q
->dma_drain_buffer
= buf
;
736 q
->dma_drain_size
= size
;
740 EXPORT_SYMBOL_GPL(blk_queue_dma_drain
);
743 * blk_queue_segment_boundary - set boundary rules for segment merging
744 * @q: the request queue for the device
745 * @mask: the memory boundary mask
747 void blk_queue_segment_boundary(struct request_queue
*q
, unsigned long mask
)
749 if (mask
< PAGE_CACHE_SIZE
- 1) {
750 mask
= PAGE_CACHE_SIZE
- 1;
751 printk(KERN_INFO
"%s: set to minimum %lx\n",
755 q
->limits
.seg_boundary_mask
= mask
;
757 EXPORT_SYMBOL(blk_queue_segment_boundary
);
760 * blk_queue_dma_alignment - set dma length and memory alignment
761 * @q: the request queue for the device
762 * @mask: alignment mask
765 * set required memory and length alignment for direct dma transactions.
766 * this is used when building direct io requests for the queue.
769 void blk_queue_dma_alignment(struct request_queue
*q
, int mask
)
771 q
->dma_alignment
= mask
;
773 EXPORT_SYMBOL(blk_queue_dma_alignment
);
776 * blk_queue_update_dma_alignment - update dma length and memory alignment
777 * @q: the request queue for the device
778 * @mask: alignment mask
781 * update required memory and length alignment for direct dma transactions.
782 * If the requested alignment is larger than the current alignment, then
783 * the current queue alignment is updated to the new value, otherwise it
784 * is left alone. The design of this is to allow multiple objects
785 * (driver, device, transport etc) to set their respective
786 * alignments without having them interfere.
789 void blk_queue_update_dma_alignment(struct request_queue
*q
, int mask
)
791 BUG_ON(mask
> PAGE_SIZE
);
793 if (mask
> q
->dma_alignment
)
794 q
->dma_alignment
= mask
;
796 EXPORT_SYMBOL(blk_queue_update_dma_alignment
);
798 static int __init
blk_settings_init(void)
800 blk_max_low_pfn
= max_low_pfn
- 1;
801 blk_max_pfn
= max_pfn
- 1;
804 subsys_initcall(blk_settings_init
);