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>
12 #include <linux/jiffies.h>
13 #include <linux/gfp.h>
17 unsigned long blk_max_low_pfn
;
18 EXPORT_SYMBOL(blk_max_low_pfn
);
20 unsigned long blk_max_pfn
;
23 * blk_queue_prep_rq - set a prepare_request function for 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
)
37 EXPORT_SYMBOL(blk_queue_prep_rq
);
40 * blk_queue_unprep_rq - set an unprepare_request function for 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
);
57 * blk_queue_merge_bvec - set a merge_bvec function for 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
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
)
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
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;
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
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().
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
)
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 q
->unplug_thresh
= 4; /* hmm */
168 q
->unplug_delay
= msecs_to_jiffies(3); /* 3 milliseconds */
169 if (q
->unplug_delay
== 0)
172 q
->unplug_timer
.function
= blk_unplug_timeout
;
173 q
->unplug_timer
.data
= (unsigned long)q
;
175 blk_set_default_limits(&q
->limits
);
176 blk_queue_max_hw_sectors(q
, BLK_SAFE_MAX_SECTORS
);
179 * by default assume old behaviour and bounce for any highmem page
181 blk_queue_bounce_limit(q
, BLK_BOUNCE_HIGH
);
183 EXPORT_SYMBOL(blk_queue_make_request
);
186 * blk_queue_bounce_limit - set bounce buffer limit for queue
187 * @q: the request queue for the device
188 * @dma_mask: the maximum address the device can handle
191 * Different hardware can have different requirements as to what pages
192 * it can do I/O directly to. A low level driver can call
193 * blk_queue_bounce_limit to have lower memory pages allocated as bounce
194 * buffers for doing I/O to pages residing above @dma_mask.
196 void blk_queue_bounce_limit(struct request_queue
*q
, u64 dma_mask
)
198 unsigned long b_pfn
= dma_mask
>> PAGE_SHIFT
;
201 q
->bounce_gfp
= GFP_NOIO
;
202 #if BITS_PER_LONG == 64
204 * Assume anything <= 4GB can be handled by IOMMU. Actually
205 * some IOMMUs can handle everything, but I don't know of a
206 * way to test this here.
208 if (b_pfn
< (min_t(u64
, 0xffffffffUL
, BLK_BOUNCE_HIGH
) >> PAGE_SHIFT
))
210 q
->limits
.bounce_pfn
= max(max_low_pfn
, b_pfn
);
212 if (b_pfn
< blk_max_low_pfn
)
214 q
->limits
.bounce_pfn
= b_pfn
;
217 init_emergency_isa_pool();
218 q
->bounce_gfp
= GFP_NOIO
| GFP_DMA
;
219 q
->limits
.bounce_pfn
= b_pfn
;
222 EXPORT_SYMBOL(blk_queue_bounce_limit
);
225 * blk_limits_max_hw_sectors - set hard and soft limit of max sectors for request
226 * @limits: the queue limits
227 * @max_hw_sectors: max hardware sectors in the usual 512b unit
230 * Enables a low level driver to set a hard upper limit,
231 * max_hw_sectors, on the size of requests. max_hw_sectors is set by
232 * the device driver based upon the combined capabilities of I/O
233 * controller and storage device.
235 * max_sectors is a soft limit imposed by the block layer for
236 * filesystem type requests. This value can be overridden on a
237 * per-device basis in /sys/block/<device>/queue/max_sectors_kb.
238 * The soft limit can not exceed max_hw_sectors.
240 void blk_limits_max_hw_sectors(struct queue_limits
*limits
, unsigned int max_hw_sectors
)
242 if ((max_hw_sectors
<< 9) < PAGE_CACHE_SIZE
) {
243 max_hw_sectors
= 1 << (PAGE_CACHE_SHIFT
- 9);
244 printk(KERN_INFO
"%s: set to minimum %d\n",
245 __func__
, max_hw_sectors
);
248 limits
->max_hw_sectors
= max_hw_sectors
;
249 limits
->max_sectors
= min_t(unsigned int, max_hw_sectors
,
250 BLK_DEF_MAX_SECTORS
);
252 EXPORT_SYMBOL(blk_limits_max_hw_sectors
);
255 * blk_queue_max_hw_sectors - set max sectors for a request for this queue
256 * @q: the request queue for the device
257 * @max_hw_sectors: max hardware sectors in the usual 512b unit
260 * See description for blk_limits_max_hw_sectors().
262 void blk_queue_max_hw_sectors(struct request_queue
*q
, unsigned int max_hw_sectors
)
264 blk_limits_max_hw_sectors(&q
->limits
, max_hw_sectors
);
266 EXPORT_SYMBOL(blk_queue_max_hw_sectors
);
269 * blk_queue_max_discard_sectors - set max sectors for a single discard
270 * @q: the request queue for the device
271 * @max_discard_sectors: maximum number of sectors to discard
273 void blk_queue_max_discard_sectors(struct request_queue
*q
,
274 unsigned int max_discard_sectors
)
276 q
->limits
.max_discard_sectors
= max_discard_sectors
;
278 EXPORT_SYMBOL(blk_queue_max_discard_sectors
);
281 * blk_queue_max_segments - set max hw segments for a request for this queue
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 * hw data segments in a request.
289 void blk_queue_max_segments(struct request_queue
*q
, unsigned short max_segments
)
293 printk(KERN_INFO
"%s: set to minimum %d\n",
294 __func__
, max_segments
);
297 q
->limits
.max_segments
= max_segments
;
299 EXPORT_SYMBOL(blk_queue_max_segments
);
302 * blk_queue_max_segment_size - set max segment size for blk_rq_map_sg
303 * @q: the request queue for the device
304 * @max_size: max size of segment in bytes
307 * Enables a low level driver to set an upper limit on the size of a
310 void blk_queue_max_segment_size(struct request_queue
*q
, unsigned int max_size
)
312 if (max_size
< PAGE_CACHE_SIZE
) {
313 max_size
= PAGE_CACHE_SIZE
;
314 printk(KERN_INFO
"%s: set to minimum %d\n",
318 q
->limits
.max_segment_size
= max_size
;
320 EXPORT_SYMBOL(blk_queue_max_segment_size
);
323 * blk_queue_logical_block_size - set logical block size for the queue
324 * @q: the request queue for the device
325 * @size: the logical block size, in bytes
328 * This should be set to the lowest possible block size that the
329 * storage device can address. The default of 512 covers most
332 void blk_queue_logical_block_size(struct request_queue
*q
, unsigned short size
)
334 q
->limits
.logical_block_size
= size
;
336 if (q
->limits
.physical_block_size
< size
)
337 q
->limits
.physical_block_size
= size
;
339 if (q
->limits
.io_min
< q
->limits
.physical_block_size
)
340 q
->limits
.io_min
= q
->limits
.physical_block_size
;
342 EXPORT_SYMBOL(blk_queue_logical_block_size
);
345 * blk_queue_physical_block_size - set physical block size for the queue
346 * @q: the request queue for the device
347 * @size: the physical block size, in bytes
350 * This should be set to the lowest possible sector size that the
351 * hardware can operate on without reverting to read-modify-write
354 void blk_queue_physical_block_size(struct request_queue
*q
, unsigned int size
)
356 q
->limits
.physical_block_size
= size
;
358 if (q
->limits
.physical_block_size
< q
->limits
.logical_block_size
)
359 q
->limits
.physical_block_size
= q
->limits
.logical_block_size
;
361 if (q
->limits
.io_min
< q
->limits
.physical_block_size
)
362 q
->limits
.io_min
= q
->limits
.physical_block_size
;
364 EXPORT_SYMBOL(blk_queue_physical_block_size
);
367 * blk_queue_alignment_offset - set physical block alignment offset
368 * @q: the request queue for the device
369 * @offset: alignment offset in bytes
372 * Some devices are naturally misaligned to compensate for things like
373 * the legacy DOS partition table 63-sector offset. Low-level drivers
374 * should call this function for devices whose first sector is not
377 void blk_queue_alignment_offset(struct request_queue
*q
, unsigned int offset
)
379 q
->limits
.alignment_offset
=
380 offset
& (q
->limits
.physical_block_size
- 1);
381 q
->limits
.misaligned
= 0;
383 EXPORT_SYMBOL(blk_queue_alignment_offset
);
386 * blk_limits_io_min - set minimum request size for a device
387 * @limits: the queue limits
388 * @min: smallest I/O size in bytes
391 * Some devices have an internal block size bigger than the reported
392 * hardware sector size. This function can be used to signal the
393 * smallest I/O the device can perform without incurring a performance
396 void blk_limits_io_min(struct queue_limits
*limits
, unsigned int min
)
398 limits
->io_min
= min
;
400 if (limits
->io_min
< limits
->logical_block_size
)
401 limits
->io_min
= limits
->logical_block_size
;
403 if (limits
->io_min
< limits
->physical_block_size
)
404 limits
->io_min
= limits
->physical_block_size
;
406 EXPORT_SYMBOL(blk_limits_io_min
);
409 * blk_queue_io_min - set minimum request size for the queue
410 * @q: the request queue for the device
411 * @min: smallest I/O size in bytes
414 * Storage devices may report a granularity or preferred minimum I/O
415 * size which is the smallest request the device can perform without
416 * incurring a performance penalty. For disk drives this is often the
417 * physical block size. For RAID arrays it is often the stripe chunk
418 * size. A properly aligned multiple of minimum_io_size is the
419 * preferred request size for workloads where a high number of I/O
420 * operations is desired.
422 void blk_queue_io_min(struct request_queue
*q
, unsigned int min
)
424 blk_limits_io_min(&q
->limits
, min
);
426 EXPORT_SYMBOL(blk_queue_io_min
);
429 * blk_limits_io_opt - set optimal request size for a device
430 * @limits: the queue limits
431 * @opt: smallest I/O size in bytes
434 * Storage devices may report an optimal I/O size, which is the
435 * device's preferred unit for sustained I/O. This is rarely reported
436 * for disk drives. For RAID arrays it is usually the stripe width or
437 * the internal track size. A properly aligned multiple of
438 * optimal_io_size is the preferred request size for workloads where
439 * sustained throughput is desired.
441 void blk_limits_io_opt(struct queue_limits
*limits
, unsigned int opt
)
443 limits
->io_opt
= opt
;
445 EXPORT_SYMBOL(blk_limits_io_opt
);
448 * blk_queue_io_opt - set optimal request size for the queue
449 * @q: the request queue for the device
450 * @opt: optimal request size in bytes
453 * Storage devices may report an optimal I/O size, which is the
454 * device's preferred unit for sustained I/O. This is rarely reported
455 * for disk drives. For RAID arrays it is usually the stripe width or
456 * the internal track size. A properly aligned multiple of
457 * optimal_io_size is the preferred request size for workloads where
458 * sustained throughput is desired.
460 void blk_queue_io_opt(struct request_queue
*q
, unsigned int opt
)
462 blk_limits_io_opt(&q
->limits
, opt
);
464 EXPORT_SYMBOL(blk_queue_io_opt
);
467 * blk_queue_stack_limits - inherit underlying queue limits for stacked drivers
468 * @t: the stacking driver (top)
469 * @b: the underlying device (bottom)
471 void blk_queue_stack_limits(struct request_queue
*t
, struct request_queue
*b
)
473 blk_stack_limits(&t
->limits
, &b
->limits
, 0);
475 EXPORT_SYMBOL(blk_queue_stack_limits
);
478 * blk_stack_limits - adjust queue_limits for stacked devices
479 * @t: the stacking driver limits (top device)
480 * @b: the underlying queue limits (bottom, component device)
481 * @start: first data sector within component device
484 * This function is used by stacking drivers like MD and DM to ensure
485 * that all component devices have compatible block sizes and
486 * alignments. The stacking driver must provide a queue_limits
487 * struct (top) and then iteratively call the stacking function for
488 * all component (bottom) devices. The stacking function will
489 * attempt to combine the values and ensure proper alignment.
491 * Returns 0 if the top and bottom queue_limits are compatible. The
492 * top device's block sizes and alignment offsets may be adjusted to
493 * ensure alignment with the bottom device. If no compatible sizes
494 * and alignments exist, -1 is returned and the resulting top
495 * queue_limits will have the misaligned flag set to indicate that
496 * the alignment_offset is undefined.
498 int blk_stack_limits(struct queue_limits
*t
, struct queue_limits
*b
,
501 unsigned int top
, bottom
, alignment
, ret
= 0;
503 t
->max_sectors
= min_not_zero(t
->max_sectors
, b
->max_sectors
);
504 t
->max_hw_sectors
= min_not_zero(t
->max_hw_sectors
, b
->max_hw_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
);
510 t
->max_segments
= min_not_zero(t
->max_segments
, b
->max_segments
);
511 t
->max_integrity_segments
= min_not_zero(t
->max_integrity_segments
,
512 b
->max_integrity_segments
);
514 t
->max_segment_size
= min_not_zero(t
->max_segment_size
,
515 b
->max_segment_size
);
517 t
->misaligned
|= b
->misaligned
;
519 alignment
= queue_limit_alignment_offset(b
, start
);
521 /* Bottom device has different alignment. Check that it is
522 * compatible with the current top alignment.
524 if (t
->alignment_offset
!= alignment
) {
526 top
= max(t
->physical_block_size
, t
->io_min
)
527 + t
->alignment_offset
;
528 bottom
= max(b
->physical_block_size
, b
->io_min
) + alignment
;
530 /* Verify that top and bottom intervals line up */
531 if (max(top
, bottom
) & (min(top
, bottom
) - 1)) {
537 t
->logical_block_size
= max(t
->logical_block_size
,
538 b
->logical_block_size
);
540 t
->physical_block_size
= max(t
->physical_block_size
,
541 b
->physical_block_size
);
543 t
->io_min
= max(t
->io_min
, b
->io_min
);
544 t
->io_opt
= lcm(t
->io_opt
, b
->io_opt
);
546 t
->cluster
&= b
->cluster
;
547 t
->discard_zeroes_data
&= b
->discard_zeroes_data
;
549 /* Physical block size a multiple of the logical block size? */
550 if (t
->physical_block_size
& (t
->logical_block_size
- 1)) {
551 t
->physical_block_size
= t
->logical_block_size
;
556 /* Minimum I/O a multiple of the physical block size? */
557 if (t
->io_min
& (t
->physical_block_size
- 1)) {
558 t
->io_min
= t
->physical_block_size
;
563 /* Optimal I/O a multiple of the physical block size? */
564 if (t
->io_opt
& (t
->physical_block_size
- 1)) {
570 /* Find lowest common alignment_offset */
571 t
->alignment_offset
= lcm(t
->alignment_offset
, alignment
)
572 & (max(t
->physical_block_size
, t
->io_min
) - 1);
574 /* Verify that new alignment_offset is on a logical block boundary */
575 if (t
->alignment_offset
& (t
->logical_block_size
- 1)) {
580 /* Discard alignment and granularity */
581 if (b
->discard_granularity
) {
582 alignment
= queue_limit_discard_alignment(b
, start
);
584 if (t
->discard_granularity
!= 0 &&
585 t
->discard_alignment
!= alignment
) {
586 top
= t
->discard_granularity
+ t
->discard_alignment
;
587 bottom
= b
->discard_granularity
+ alignment
;
589 /* Verify that top and bottom intervals line up */
590 if (max(top
, bottom
) & (min(top
, bottom
) - 1))
591 t
->discard_misaligned
= 1;
594 t
->max_discard_sectors
= min_not_zero(t
->max_discard_sectors
,
595 b
->max_discard_sectors
);
596 t
->discard_granularity
= max(t
->discard_granularity
,
597 b
->discard_granularity
);
598 t
->discard_alignment
= lcm(t
->discard_alignment
, alignment
) &
599 (t
->discard_granularity
- 1);
604 EXPORT_SYMBOL(blk_stack_limits
);
607 * bdev_stack_limits - adjust queue limits for stacked drivers
608 * @t: the stacking driver limits (top device)
609 * @bdev: the component block_device (bottom)
610 * @start: first data sector within component device
613 * Merges queue limits for a top device and a block_device. Returns
614 * 0 if alignment didn't change. Returns -1 if adding the bottom
615 * device caused misalignment.
617 int bdev_stack_limits(struct queue_limits
*t
, struct block_device
*bdev
,
620 struct request_queue
*bq
= bdev_get_queue(bdev
);
622 start
+= get_start_sect(bdev
);
624 return blk_stack_limits(t
, &bq
->limits
, start
);
626 EXPORT_SYMBOL(bdev_stack_limits
);
629 * disk_stack_limits - adjust queue limits for stacked drivers
630 * @disk: MD/DM gendisk (top)
631 * @bdev: the underlying block device (bottom)
632 * @offset: offset to beginning of data within component device
635 * Merges the limits for a top level gendisk and a bottom level
638 void disk_stack_limits(struct gendisk
*disk
, struct block_device
*bdev
,
641 struct request_queue
*t
= disk
->queue
;
643 if (bdev_stack_limits(&t
->limits
, bdev
, offset
>> 9) < 0) {
644 char top
[BDEVNAME_SIZE
], bottom
[BDEVNAME_SIZE
];
646 disk_name(disk
, 0, top
);
647 bdevname(bdev
, bottom
);
649 printk(KERN_NOTICE
"%s: Warning: Device %s is misaligned\n",
653 EXPORT_SYMBOL(disk_stack_limits
);
656 * blk_queue_dma_pad - set pad mask
657 * @q: the request queue for the device
662 * Appending pad buffer to a request modifies the last entry of a
663 * scatter list such that it includes the pad buffer.
665 void blk_queue_dma_pad(struct request_queue
*q
, unsigned int mask
)
667 q
->dma_pad_mask
= mask
;
669 EXPORT_SYMBOL(blk_queue_dma_pad
);
672 * blk_queue_update_dma_pad - update pad mask
673 * @q: the request queue for the device
676 * Update dma pad mask.
678 * Appending pad buffer to a request modifies the last entry of a
679 * scatter list such that it includes the pad buffer.
681 void blk_queue_update_dma_pad(struct request_queue
*q
, unsigned int mask
)
683 if (mask
> q
->dma_pad_mask
)
684 q
->dma_pad_mask
= mask
;
686 EXPORT_SYMBOL(blk_queue_update_dma_pad
);
689 * blk_queue_dma_drain - Set up a drain buffer for excess dma.
690 * @q: the request queue for the device
691 * @dma_drain_needed: fn which returns non-zero if drain is necessary
692 * @buf: physically contiguous buffer
693 * @size: size of the buffer in bytes
695 * Some devices have excess DMA problems and can't simply discard (or
696 * zero fill) the unwanted piece of the transfer. They have to have a
697 * real area of memory to transfer it into. The use case for this is
698 * ATAPI devices in DMA mode. If the packet command causes a transfer
699 * bigger than the transfer size some HBAs will lock up if there
700 * aren't DMA elements to contain the excess transfer. What this API
701 * does is adjust the queue so that the buf is always appended
702 * silently to the scatterlist.
704 * Note: This routine adjusts max_hw_segments to make room for appending
705 * the drain buffer. If you call blk_queue_max_segments() after calling
706 * this routine, you must set the limit to one fewer than your device
707 * can support otherwise there won't be room for the drain buffer.
709 int blk_queue_dma_drain(struct request_queue
*q
,
710 dma_drain_needed_fn
*dma_drain_needed
,
711 void *buf
, unsigned int size
)
713 if (queue_max_segments(q
) < 2)
715 /* make room for appending the drain */
716 blk_queue_max_segments(q
, queue_max_segments(q
) - 1);
717 q
->dma_drain_needed
= dma_drain_needed
;
718 q
->dma_drain_buffer
= buf
;
719 q
->dma_drain_size
= size
;
723 EXPORT_SYMBOL_GPL(blk_queue_dma_drain
);
726 * blk_queue_segment_boundary - set boundary rules for segment merging
727 * @q: the request queue for the device
728 * @mask: the memory boundary mask
730 void blk_queue_segment_boundary(struct request_queue
*q
, unsigned long mask
)
732 if (mask
< PAGE_CACHE_SIZE
- 1) {
733 mask
= PAGE_CACHE_SIZE
- 1;
734 printk(KERN_INFO
"%s: set to minimum %lx\n",
738 q
->limits
.seg_boundary_mask
= mask
;
740 EXPORT_SYMBOL(blk_queue_segment_boundary
);
743 * blk_queue_dma_alignment - set dma length and memory alignment
744 * @q: the request queue for the device
745 * @mask: alignment mask
748 * set required memory and length alignment for direct dma transactions.
749 * this is used when building direct io requests for the queue.
752 void blk_queue_dma_alignment(struct request_queue
*q
, int mask
)
754 q
->dma_alignment
= mask
;
756 EXPORT_SYMBOL(blk_queue_dma_alignment
);
759 * blk_queue_update_dma_alignment - update dma length and memory alignment
760 * @q: the request queue for the device
761 * @mask: alignment mask
764 * update required memory and length alignment for direct dma transactions.
765 * If the requested alignment is larger than the current alignment, then
766 * the current queue alignment is updated to the new value, otherwise it
767 * is left alone. The design of this is to allow multiple objects
768 * (driver, device, transport etc) to set their respective
769 * alignments without having them interfere.
772 void blk_queue_update_dma_alignment(struct request_queue
*q
, int mask
)
774 BUG_ON(mask
> PAGE_SIZE
);
776 if (mask
> q
->dma_alignment
)
777 q
->dma_alignment
= mask
;
779 EXPORT_SYMBOL(blk_queue_update_dma_alignment
);
782 * blk_queue_flush - configure queue's cache flush capability
783 * @q: the request queue for the device
784 * @flush: 0, REQ_FLUSH or REQ_FLUSH | REQ_FUA
786 * Tell block layer cache flush capability of @q. If it supports
787 * flushing, REQ_FLUSH should be set. If it supports bypassing
788 * write cache for individual writes, REQ_FUA should be set.
790 void blk_queue_flush(struct request_queue
*q
, unsigned int flush
)
792 WARN_ON_ONCE(flush
& ~(REQ_FLUSH
| REQ_FUA
));
794 if (WARN_ON_ONCE(!(flush
& REQ_FLUSH
) && (flush
& REQ_FUA
)))
797 q
->flush_flags
= flush
& (REQ_FLUSH
| REQ_FUA
);
799 EXPORT_SYMBOL_GPL(blk_queue_flush
);
801 static int __init
blk_settings_init(void)
803 blk_max_low_pfn
= max_low_pfn
- 1;
804 blk_max_pfn
= max_pfn
- 1;
807 subsys_initcall(blk_settings_init
);