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
);
56 void blk_queue_softirq_done(struct request_queue
*q
, softirq_done_fn
*fn
)
58 q
->softirq_done_fn
= fn
;
60 EXPORT_SYMBOL(blk_queue_softirq_done
);
62 void blk_queue_rq_timeout(struct request_queue
*q
, unsigned int timeout
)
64 q
->rq_timeout
= timeout
;
66 EXPORT_SYMBOL_GPL(blk_queue_rq_timeout
);
68 void blk_queue_rq_timed_out(struct request_queue
*q
, rq_timed_out_fn
*fn
)
70 q
->rq_timed_out_fn
= fn
;
72 EXPORT_SYMBOL_GPL(blk_queue_rq_timed_out
);
74 void blk_queue_lld_busy(struct request_queue
*q
, lld_busy_fn
*fn
)
78 EXPORT_SYMBOL_GPL(blk_queue_lld_busy
);
81 * blk_set_default_limits - reset limits to default values
82 * @lim: the queue_limits structure to reset
85 * Returns a queue_limit struct to its default state.
87 void blk_set_default_limits(struct queue_limits
*lim
)
89 lim
->max_segments
= BLK_MAX_SEGMENTS
;
90 lim
->max_integrity_segments
= 0;
91 lim
->seg_boundary_mask
= BLK_SEG_BOUNDARY_MASK
;
92 lim
->virt_boundary_mask
= 0;
93 lim
->max_segment_size
= BLK_MAX_SEGMENT_SIZE
;
94 lim
->max_sectors
= lim
->max_hw_sectors
= BLK_SAFE_MAX_SECTORS
;
95 lim
->max_dev_sectors
= 0;
96 lim
->chunk_sectors
= 0;
97 lim
->max_write_same_sectors
= 0;
98 lim
->max_discard_sectors
= 0;
99 lim
->max_hw_discard_sectors
= 0;
100 lim
->discard_granularity
= 0;
101 lim
->discard_alignment
= 0;
102 lim
->discard_misaligned
= 0;
103 lim
->discard_zeroes_data
= 0;
104 lim
->logical_block_size
= lim
->physical_block_size
= lim
->io_min
= 512;
105 lim
->bounce_pfn
= (unsigned long)(BLK_BOUNCE_ANY
>> PAGE_SHIFT
);
106 lim
->alignment_offset
= 0;
111 EXPORT_SYMBOL(blk_set_default_limits
);
114 * blk_set_stacking_limits - set default limits for stacking devices
115 * @lim: the queue_limits structure to reset
118 * Returns a queue_limit struct to its default state. Should be used
119 * by stacking drivers like DM that have no internal limits.
121 void blk_set_stacking_limits(struct queue_limits
*lim
)
123 blk_set_default_limits(lim
);
125 /* Inherit limits from component devices */
126 lim
->discard_zeroes_data
= 1;
127 lim
->max_segments
= USHRT_MAX
;
128 lim
->max_hw_sectors
= UINT_MAX
;
129 lim
->max_segment_size
= UINT_MAX
;
130 lim
->max_sectors
= UINT_MAX
;
131 lim
->max_dev_sectors
= UINT_MAX
;
132 lim
->max_write_same_sectors
= UINT_MAX
;
134 EXPORT_SYMBOL(blk_set_stacking_limits
);
137 * blk_queue_make_request - define an alternate make_request function for a device
138 * @q: the request queue for the device to be affected
139 * @mfn: the alternate make_request function
142 * The normal way for &struct bios to be passed to a device
143 * driver is for them to be collected into requests on a request
144 * queue, and then to allow the device driver to select requests
145 * off that queue when it is ready. This works well for many block
146 * devices. However some block devices (typically virtual devices
147 * such as md or lvm) do not benefit from the processing on the
148 * request queue, and are served best by having the requests passed
149 * directly to them. This can be achieved by providing a function
150 * to blk_queue_make_request().
153 * The driver that does this *must* be able to deal appropriately
154 * with buffers in "highmemory". This can be accomplished by either calling
155 * __bio_kmap_atomic() to get a temporary kernel mapping, or by calling
156 * blk_queue_bounce() to create a buffer in normal memory.
158 void blk_queue_make_request(struct request_queue
*q
, make_request_fn
*mfn
)
163 q
->nr_requests
= BLKDEV_MAX_RQ
;
165 q
->make_request_fn
= mfn
;
166 blk_queue_dma_alignment(q
, 511);
167 blk_queue_congestion_threshold(q
);
168 q
->nr_batching
= BLK_BATCH_REQ
;
170 blk_set_default_limits(&q
->limits
);
173 * by default assume old behaviour and bounce for any highmem page
175 blk_queue_bounce_limit(q
, BLK_BOUNCE_HIGH
);
177 EXPORT_SYMBOL(blk_queue_make_request
);
180 * blk_queue_bounce_limit - set bounce buffer limit for queue
181 * @q: the request queue for the device
182 * @max_addr: the maximum address the device can handle
185 * Different hardware can have different requirements as to what pages
186 * it can do I/O directly to. A low level driver can call
187 * blk_queue_bounce_limit to have lower memory pages allocated as bounce
188 * buffers for doing I/O to pages residing above @max_addr.
190 void blk_queue_bounce_limit(struct request_queue
*q
, u64 max_addr
)
192 unsigned long b_pfn
= max_addr
>> PAGE_SHIFT
;
195 q
->bounce_gfp
= GFP_NOIO
;
196 #if BITS_PER_LONG == 64
198 * Assume anything <= 4GB can be handled by IOMMU. Actually
199 * some IOMMUs can handle everything, but I don't know of a
200 * way to test this here.
202 if (b_pfn
< (min_t(u64
, 0xffffffffUL
, BLK_BOUNCE_HIGH
) >> PAGE_SHIFT
))
204 q
->limits
.bounce_pfn
= max(max_low_pfn
, b_pfn
);
206 if (b_pfn
< blk_max_low_pfn
)
208 q
->limits
.bounce_pfn
= b_pfn
;
211 init_emergency_isa_pool();
212 q
->bounce_gfp
= GFP_NOIO
| GFP_DMA
;
213 q
->limits
.bounce_pfn
= b_pfn
;
216 EXPORT_SYMBOL(blk_queue_bounce_limit
);
219 * blk_queue_max_hw_sectors - set max sectors for a request for this queue
220 * @q: the request queue for the device
221 * @max_hw_sectors: max hardware sectors in the usual 512b unit
224 * Enables a low level driver to set a hard upper limit,
225 * max_hw_sectors, on the size of requests. max_hw_sectors is set by
226 * the device driver based upon the capabilities of the I/O
229 * max_dev_sectors is a hard limit imposed by the storage device for
230 * READ/WRITE requests. It is set by the disk driver.
232 * max_sectors is a soft limit imposed by the block layer for
233 * filesystem type requests. This value can be overridden on a
234 * per-device basis in /sys/block/<device>/queue/max_sectors_kb.
235 * The soft limit can not exceed max_hw_sectors.
237 void blk_queue_max_hw_sectors(struct request_queue
*q
, unsigned int max_hw_sectors
)
239 struct queue_limits
*limits
= &q
->limits
;
240 unsigned int max_sectors
;
242 if ((max_hw_sectors
<< 9) < PAGE_SIZE
) {
243 max_hw_sectors
= 1 << (PAGE_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 max_sectors
= min_not_zero(max_hw_sectors
, limits
->max_dev_sectors
);
250 max_sectors
= min_t(unsigned int, max_sectors
, BLK_DEF_MAX_SECTORS
);
251 limits
->max_sectors
= max_sectors
;
252 q
->backing_dev_info
.io_pages
= max_sectors
>> (PAGE_SHIFT
- 9);
254 EXPORT_SYMBOL(blk_queue_max_hw_sectors
);
257 * blk_queue_chunk_sectors - set size of the chunk for this queue
258 * @q: the request queue for the device
259 * @chunk_sectors: chunk sectors in the usual 512b unit
262 * If a driver doesn't want IOs to cross a given chunk size, it can set
263 * this limit and prevent merging across chunks. Note that the chunk size
264 * must currently be a power-of-2 in sectors. Also note that the block
265 * layer must accept a page worth of data at any offset. So if the
266 * crossing of chunks is a hard limitation in the driver, it must still be
267 * prepared to split single page bios.
269 void blk_queue_chunk_sectors(struct request_queue
*q
, unsigned int chunk_sectors
)
271 BUG_ON(!is_power_of_2(chunk_sectors
));
272 q
->limits
.chunk_sectors
= chunk_sectors
;
274 EXPORT_SYMBOL(blk_queue_chunk_sectors
);
277 * blk_queue_max_discard_sectors - set max sectors for a single discard
278 * @q: the request queue for the device
279 * @max_discard_sectors: maximum number of sectors to discard
281 void blk_queue_max_discard_sectors(struct request_queue
*q
,
282 unsigned int max_discard_sectors
)
284 q
->limits
.max_hw_discard_sectors
= max_discard_sectors
;
285 q
->limits
.max_discard_sectors
= max_discard_sectors
;
287 EXPORT_SYMBOL(blk_queue_max_discard_sectors
);
290 * blk_queue_max_write_same_sectors - set max sectors for a single write same
291 * @q: the request queue for the device
292 * @max_write_same_sectors: maximum number of sectors to write per command
294 void blk_queue_max_write_same_sectors(struct request_queue
*q
,
295 unsigned int max_write_same_sectors
)
297 q
->limits
.max_write_same_sectors
= max_write_same_sectors
;
299 EXPORT_SYMBOL(blk_queue_max_write_same_sectors
);
302 * blk_queue_max_segments - set max hw segments for a request for this queue
303 * @q: the request queue for the device
304 * @max_segments: max number of segments
307 * Enables a low level driver to set an upper limit on the number of
308 * hw data segments in a request.
310 void blk_queue_max_segments(struct request_queue
*q
, unsigned short max_segments
)
314 printk(KERN_INFO
"%s: set to minimum %d\n",
315 __func__
, max_segments
);
318 q
->limits
.max_segments
= max_segments
;
320 EXPORT_SYMBOL(blk_queue_max_segments
);
323 * blk_queue_max_segment_size - set max segment size for blk_rq_map_sg
324 * @q: the request queue for the device
325 * @max_size: max size of segment in bytes
328 * Enables a low level driver to set an upper limit on the size of a
331 void blk_queue_max_segment_size(struct request_queue
*q
, unsigned int max_size
)
333 if (max_size
< PAGE_SIZE
) {
334 max_size
= PAGE_SIZE
;
335 printk(KERN_INFO
"%s: set to minimum %d\n",
339 q
->limits
.max_segment_size
= max_size
;
341 EXPORT_SYMBOL(blk_queue_max_segment_size
);
344 * blk_queue_logical_block_size - set logical block size for the queue
345 * @q: the request queue for the device
346 * @size: the logical block size, in bytes
349 * This should be set to the lowest possible block size that the
350 * storage device can address. The default of 512 covers most
353 void blk_queue_logical_block_size(struct request_queue
*q
, unsigned short size
)
355 q
->limits
.logical_block_size
= size
;
357 if (q
->limits
.physical_block_size
< size
)
358 q
->limits
.physical_block_size
= size
;
360 if (q
->limits
.io_min
< q
->limits
.physical_block_size
)
361 q
->limits
.io_min
= q
->limits
.physical_block_size
;
363 EXPORT_SYMBOL(blk_queue_logical_block_size
);
366 * blk_queue_physical_block_size - set physical block size for the queue
367 * @q: the request queue for the device
368 * @size: the physical block size, in bytes
371 * This should be set to the lowest possible sector size that the
372 * hardware can operate on without reverting to read-modify-write
375 void blk_queue_physical_block_size(struct request_queue
*q
, unsigned int size
)
377 q
->limits
.physical_block_size
= size
;
379 if (q
->limits
.physical_block_size
< q
->limits
.logical_block_size
)
380 q
->limits
.physical_block_size
= q
->limits
.logical_block_size
;
382 if (q
->limits
.io_min
< q
->limits
.physical_block_size
)
383 q
->limits
.io_min
= q
->limits
.physical_block_size
;
385 EXPORT_SYMBOL(blk_queue_physical_block_size
);
388 * blk_queue_alignment_offset - set physical block alignment offset
389 * @q: the request queue for the device
390 * @offset: alignment offset in bytes
393 * Some devices are naturally misaligned to compensate for things like
394 * the legacy DOS partition table 63-sector offset. Low-level drivers
395 * should call this function for devices whose first sector is not
398 void blk_queue_alignment_offset(struct request_queue
*q
, unsigned int offset
)
400 q
->limits
.alignment_offset
=
401 offset
& (q
->limits
.physical_block_size
- 1);
402 q
->limits
.misaligned
= 0;
404 EXPORT_SYMBOL(blk_queue_alignment_offset
);
407 * blk_limits_io_min - set minimum request size for a device
408 * @limits: the queue limits
409 * @min: smallest I/O size in bytes
412 * Some devices have an internal block size bigger than the reported
413 * hardware sector size. This function can be used to signal the
414 * smallest I/O the device can perform without incurring a performance
417 void blk_limits_io_min(struct queue_limits
*limits
, unsigned int min
)
419 limits
->io_min
= min
;
421 if (limits
->io_min
< limits
->logical_block_size
)
422 limits
->io_min
= limits
->logical_block_size
;
424 if (limits
->io_min
< limits
->physical_block_size
)
425 limits
->io_min
= limits
->physical_block_size
;
427 EXPORT_SYMBOL(blk_limits_io_min
);
430 * blk_queue_io_min - set minimum request size for the queue
431 * @q: the request queue for the device
432 * @min: smallest I/O size in bytes
435 * Storage devices may report a granularity or preferred minimum I/O
436 * size which is the smallest request the device can perform without
437 * incurring a performance penalty. For disk drives this is often the
438 * physical block size. For RAID arrays it is often the stripe chunk
439 * size. A properly aligned multiple of minimum_io_size is the
440 * preferred request size for workloads where a high number of I/O
441 * operations is desired.
443 void blk_queue_io_min(struct request_queue
*q
, unsigned int min
)
445 blk_limits_io_min(&q
->limits
, min
);
447 EXPORT_SYMBOL(blk_queue_io_min
);
450 * blk_limits_io_opt - set optimal request size for a device
451 * @limits: the queue limits
452 * @opt: smallest I/O size in bytes
455 * Storage devices may report an optimal I/O size, which is the
456 * device's preferred unit for sustained I/O. This is rarely reported
457 * for disk drives. For RAID arrays it is usually the stripe width or
458 * the internal track size. A properly aligned multiple of
459 * optimal_io_size is the preferred request size for workloads where
460 * sustained throughput is desired.
462 void blk_limits_io_opt(struct queue_limits
*limits
, unsigned int opt
)
464 limits
->io_opt
= opt
;
466 EXPORT_SYMBOL(blk_limits_io_opt
);
469 * blk_queue_io_opt - set optimal request size for the queue
470 * @q: the request queue for the device
471 * @opt: optimal request size in bytes
474 * Storage devices may report an optimal I/O size, which is the
475 * device's preferred unit for sustained I/O. This is rarely reported
476 * for disk drives. For RAID arrays it is usually the stripe width or
477 * the internal track size. A properly aligned multiple of
478 * optimal_io_size is the preferred request size for workloads where
479 * sustained throughput is desired.
481 void blk_queue_io_opt(struct request_queue
*q
, unsigned int opt
)
483 blk_limits_io_opt(&q
->limits
, opt
);
485 EXPORT_SYMBOL(blk_queue_io_opt
);
488 * blk_queue_stack_limits - inherit underlying queue limits for stacked drivers
489 * @t: the stacking driver (top)
490 * @b: the underlying device (bottom)
492 void blk_queue_stack_limits(struct request_queue
*t
, struct request_queue
*b
)
494 blk_stack_limits(&t
->limits
, &b
->limits
, 0);
496 EXPORT_SYMBOL(blk_queue_stack_limits
);
499 * blk_stack_limits - adjust queue_limits for stacked devices
500 * @t: the stacking driver limits (top device)
501 * @b: the underlying queue limits (bottom, component device)
502 * @start: first data sector within component device
505 * This function is used by stacking drivers like MD and DM to ensure
506 * that all component devices have compatible block sizes and
507 * alignments. The stacking driver must provide a queue_limits
508 * struct (top) and then iteratively call the stacking function for
509 * all component (bottom) devices. The stacking function will
510 * attempt to combine the values and ensure proper alignment.
512 * Returns 0 if the top and bottom queue_limits are compatible. The
513 * top device's block sizes and alignment offsets may be adjusted to
514 * ensure alignment with the bottom device. If no compatible sizes
515 * and alignments exist, -1 is returned and the resulting top
516 * queue_limits will have the misaligned flag set to indicate that
517 * the alignment_offset is undefined.
519 int blk_stack_limits(struct queue_limits
*t
, struct queue_limits
*b
,
522 unsigned int top
, bottom
, alignment
, ret
= 0;
524 t
->max_sectors
= min_not_zero(t
->max_sectors
, b
->max_sectors
);
525 t
->max_hw_sectors
= min_not_zero(t
->max_hw_sectors
, b
->max_hw_sectors
);
526 t
->max_dev_sectors
= min_not_zero(t
->max_dev_sectors
, b
->max_dev_sectors
);
527 t
->max_write_same_sectors
= min(t
->max_write_same_sectors
,
528 b
->max_write_same_sectors
);
529 t
->bounce_pfn
= min_not_zero(t
->bounce_pfn
, b
->bounce_pfn
);
531 t
->seg_boundary_mask
= min_not_zero(t
->seg_boundary_mask
,
532 b
->seg_boundary_mask
);
533 t
->virt_boundary_mask
= min_not_zero(t
->virt_boundary_mask
,
534 b
->virt_boundary_mask
);
536 t
->max_segments
= min_not_zero(t
->max_segments
, b
->max_segments
);
537 t
->max_integrity_segments
= min_not_zero(t
->max_integrity_segments
,
538 b
->max_integrity_segments
);
540 t
->max_segment_size
= min_not_zero(t
->max_segment_size
,
541 b
->max_segment_size
);
543 t
->misaligned
|= b
->misaligned
;
545 alignment
= queue_limit_alignment_offset(b
, start
);
547 /* Bottom device has different alignment. Check that it is
548 * compatible with the current top alignment.
550 if (t
->alignment_offset
!= alignment
) {
552 top
= max(t
->physical_block_size
, t
->io_min
)
553 + t
->alignment_offset
;
554 bottom
= max(b
->physical_block_size
, b
->io_min
) + alignment
;
556 /* Verify that top and bottom intervals line up */
557 if (max(top
, bottom
) % min(top
, bottom
)) {
563 t
->logical_block_size
= max(t
->logical_block_size
,
564 b
->logical_block_size
);
566 t
->physical_block_size
= max(t
->physical_block_size
,
567 b
->physical_block_size
);
569 t
->io_min
= max(t
->io_min
, b
->io_min
);
570 t
->io_opt
= lcm_not_zero(t
->io_opt
, b
->io_opt
);
572 t
->cluster
&= b
->cluster
;
573 t
->discard_zeroes_data
&= b
->discard_zeroes_data
;
575 /* Physical block size a multiple of the logical block size? */
576 if (t
->physical_block_size
& (t
->logical_block_size
- 1)) {
577 t
->physical_block_size
= t
->logical_block_size
;
582 /* Minimum I/O a multiple of the physical block size? */
583 if (t
->io_min
& (t
->physical_block_size
- 1)) {
584 t
->io_min
= t
->physical_block_size
;
589 /* Optimal I/O a multiple of the physical block size? */
590 if (t
->io_opt
& (t
->physical_block_size
- 1)) {
596 t
->raid_partial_stripes_expensive
=
597 max(t
->raid_partial_stripes_expensive
,
598 b
->raid_partial_stripes_expensive
);
600 /* Find lowest common alignment_offset */
601 t
->alignment_offset
= lcm_not_zero(t
->alignment_offset
, alignment
)
602 % max(t
->physical_block_size
, t
->io_min
);
604 /* Verify that new alignment_offset is on a logical block boundary */
605 if (t
->alignment_offset
& (t
->logical_block_size
- 1)) {
610 /* Discard alignment and granularity */
611 if (b
->discard_granularity
) {
612 alignment
= queue_limit_discard_alignment(b
, start
);
614 if (t
->discard_granularity
!= 0 &&
615 t
->discard_alignment
!= alignment
) {
616 top
= t
->discard_granularity
+ t
->discard_alignment
;
617 bottom
= b
->discard_granularity
+ alignment
;
619 /* Verify that top and bottom intervals line up */
620 if ((max(top
, bottom
) % min(top
, bottom
)) != 0)
621 t
->discard_misaligned
= 1;
624 t
->max_discard_sectors
= min_not_zero(t
->max_discard_sectors
,
625 b
->max_discard_sectors
);
626 t
->max_hw_discard_sectors
= min_not_zero(t
->max_hw_discard_sectors
,
627 b
->max_hw_discard_sectors
);
628 t
->discard_granularity
= max(t
->discard_granularity
,
629 b
->discard_granularity
);
630 t
->discard_alignment
= lcm_not_zero(t
->discard_alignment
, alignment
) %
631 t
->discard_granularity
;
636 EXPORT_SYMBOL(blk_stack_limits
);
639 * bdev_stack_limits - adjust queue limits for stacked drivers
640 * @t: the stacking driver limits (top device)
641 * @bdev: the component block_device (bottom)
642 * @start: first data sector within component device
645 * Merges queue limits for a top device and a block_device. Returns
646 * 0 if alignment didn't change. Returns -1 if adding the bottom
647 * device caused misalignment.
649 int bdev_stack_limits(struct queue_limits
*t
, struct block_device
*bdev
,
652 struct request_queue
*bq
= bdev_get_queue(bdev
);
654 start
+= get_start_sect(bdev
);
656 return blk_stack_limits(t
, &bq
->limits
, start
);
658 EXPORT_SYMBOL(bdev_stack_limits
);
661 * disk_stack_limits - adjust queue limits for stacked drivers
662 * @disk: MD/DM gendisk (top)
663 * @bdev: the underlying block device (bottom)
664 * @offset: offset to beginning of data within component device
667 * Merges the limits for a top level gendisk and a bottom level
670 void disk_stack_limits(struct gendisk
*disk
, struct block_device
*bdev
,
673 struct request_queue
*t
= disk
->queue
;
675 if (bdev_stack_limits(&t
->limits
, bdev
, offset
>> 9) < 0) {
676 char top
[BDEVNAME_SIZE
], bottom
[BDEVNAME_SIZE
];
678 disk_name(disk
, 0, top
);
679 bdevname(bdev
, bottom
);
681 printk(KERN_NOTICE
"%s: Warning: Device %s is misaligned\n",
685 EXPORT_SYMBOL(disk_stack_limits
);
688 * blk_queue_dma_pad - set pad mask
689 * @q: the request queue for the device
694 * Appending pad buffer to a request modifies the last entry of a
695 * scatter list such that it includes the pad buffer.
697 void blk_queue_dma_pad(struct request_queue
*q
, unsigned int mask
)
699 q
->dma_pad_mask
= mask
;
701 EXPORT_SYMBOL(blk_queue_dma_pad
);
704 * blk_queue_update_dma_pad - update pad mask
705 * @q: the request queue for the device
708 * Update dma pad mask.
710 * Appending pad buffer to a request modifies the last entry of a
711 * scatter list such that it includes the pad buffer.
713 void blk_queue_update_dma_pad(struct request_queue
*q
, unsigned int mask
)
715 if (mask
> q
->dma_pad_mask
)
716 q
->dma_pad_mask
= mask
;
718 EXPORT_SYMBOL(blk_queue_update_dma_pad
);
721 * blk_queue_dma_drain - Set up a drain buffer for excess dma.
722 * @q: the request queue for the device
723 * @dma_drain_needed: fn which returns non-zero if drain is necessary
724 * @buf: physically contiguous buffer
725 * @size: size of the buffer in bytes
727 * Some devices have excess DMA problems and can't simply discard (or
728 * zero fill) the unwanted piece of the transfer. They have to have a
729 * real area of memory to transfer it into. The use case for this is
730 * ATAPI devices in DMA mode. If the packet command causes a transfer
731 * bigger than the transfer size some HBAs will lock up if there
732 * aren't DMA elements to contain the excess transfer. What this API
733 * does is adjust the queue so that the buf is always appended
734 * silently to the scatterlist.
736 * Note: This routine adjusts max_hw_segments to make room for appending
737 * the drain buffer. If you call blk_queue_max_segments() after calling
738 * this routine, you must set the limit to one fewer than your device
739 * can support otherwise there won't be room for the drain buffer.
741 int blk_queue_dma_drain(struct request_queue
*q
,
742 dma_drain_needed_fn
*dma_drain_needed
,
743 void *buf
, unsigned int size
)
745 if (queue_max_segments(q
) < 2)
747 /* make room for appending the drain */
748 blk_queue_max_segments(q
, queue_max_segments(q
) - 1);
749 q
->dma_drain_needed
= dma_drain_needed
;
750 q
->dma_drain_buffer
= buf
;
751 q
->dma_drain_size
= size
;
755 EXPORT_SYMBOL_GPL(blk_queue_dma_drain
);
758 * blk_queue_segment_boundary - set boundary rules for segment merging
759 * @q: the request queue for the device
760 * @mask: the memory boundary mask
762 void blk_queue_segment_boundary(struct request_queue
*q
, unsigned long mask
)
764 if (mask
< PAGE_SIZE
- 1) {
765 mask
= PAGE_SIZE
- 1;
766 printk(KERN_INFO
"%s: set to minimum %lx\n",
770 q
->limits
.seg_boundary_mask
= mask
;
772 EXPORT_SYMBOL(blk_queue_segment_boundary
);
775 * blk_queue_virt_boundary - set boundary rules for bio merging
776 * @q: the request queue for the device
777 * @mask: the memory boundary mask
779 void blk_queue_virt_boundary(struct request_queue
*q
, unsigned long mask
)
781 q
->limits
.virt_boundary_mask
= mask
;
783 EXPORT_SYMBOL(blk_queue_virt_boundary
);
786 * blk_queue_dma_alignment - set dma length and memory alignment
787 * @q: the request queue for the device
788 * @mask: alignment mask
791 * set required memory and length alignment for direct dma transactions.
792 * this is used when building direct io requests for the queue.
795 void blk_queue_dma_alignment(struct request_queue
*q
, int mask
)
797 q
->dma_alignment
= mask
;
799 EXPORT_SYMBOL(blk_queue_dma_alignment
);
802 * blk_queue_update_dma_alignment - update dma length and memory alignment
803 * @q: the request queue for the device
804 * @mask: alignment mask
807 * update required memory and length alignment for direct dma transactions.
808 * If the requested alignment is larger than the current alignment, then
809 * the current queue alignment is updated to the new value, otherwise it
810 * is left alone. The design of this is to allow multiple objects
811 * (driver, device, transport etc) to set their respective
812 * alignments without having them interfere.
815 void blk_queue_update_dma_alignment(struct request_queue
*q
, int mask
)
817 BUG_ON(mask
> PAGE_SIZE
);
819 if (mask
> q
->dma_alignment
)
820 q
->dma_alignment
= mask
;
822 EXPORT_SYMBOL(blk_queue_update_dma_alignment
);
824 void blk_queue_flush_queueable(struct request_queue
*q
, bool queueable
)
826 spin_lock_irq(q
->queue_lock
);
828 clear_bit(QUEUE_FLAG_FLUSH_NQ
, &q
->queue_flags
);
830 set_bit(QUEUE_FLAG_FLUSH_NQ
, &q
->queue_flags
);
831 spin_unlock_irq(q
->queue_lock
);
833 EXPORT_SYMBOL_GPL(blk_queue_flush_queueable
);
836 * blk_queue_write_cache - configure queue's write cache
837 * @q: the request queue for the device
838 * @wc: write back cache on or off
839 * @fua: device supports FUA writes, if true
841 * Tell the block layer about the write cache of @q.
843 void blk_queue_write_cache(struct request_queue
*q
, bool wc
, bool fua
)
845 spin_lock_irq(q
->queue_lock
);
847 queue_flag_set(QUEUE_FLAG_WC
, q
);
849 queue_flag_clear(QUEUE_FLAG_WC
, q
);
851 queue_flag_set(QUEUE_FLAG_FUA
, q
);
853 queue_flag_clear(QUEUE_FLAG_FUA
, q
);
854 spin_unlock_irq(q
->queue_lock
);
856 EXPORT_SYMBOL_GPL(blk_queue_write_cache
);
858 static int __init
blk_settings_init(void)
860 blk_max_low_pfn
= max_low_pfn
- 1;
861 blk_max_pfn
= max_pfn
- 1;
864 subsys_initcall(blk_settings_init
);