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Jens Axboe86db1e22008-01-29 14:53:40 +01001/*
2 * Functions related to setting various queue properties from drivers
3 */
4#include <linux/kernel.h>
5#include <linux/module.h>
6#include <linux/init.h>
7#include <linux/bio.h>
8#include <linux/blkdev.h>
9#include <linux/bootmem.h> /* for max_pfn/max_low_pfn */
Martin K. Petersen70dd5bf2009-07-31 11:49:12 -040010#include <linux/gcd.h>
Martin K. Petersen2cda2722010-03-15 12:46:51 +010011#include <linux/lcm.h>
Randy Dunlapad5ebd22009-11-11 13:47:45 +010012#include <linux/jiffies.h>
Tejun Heo5a0e3ad2010-03-24 17:04:11 +090013#include <linux/gfp.h>
Jens Axboe86db1e22008-01-29 14:53:40 +010014
15#include "blk.h"
16
Jens Axboe6728cb02008-01-31 13:03:55 +010017unsigned long blk_max_low_pfn;
Jens Axboe86db1e22008-01-29 14:53:40 +010018EXPORT_SYMBOL(blk_max_low_pfn);
Jens Axboe6728cb02008-01-31 13:03:55 +010019
20unsigned long blk_max_pfn;
Jens Axboe86db1e22008-01-29 14:53:40 +010021
22/**
23 * blk_queue_prep_rq - set a prepare_request function for queue
24 * @q: queue
25 * @pfn: prepare_request function
26 *
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.
31 *
32 */
33void blk_queue_prep_rq(struct request_queue *q, prep_rq_fn *pfn)
34{
35 q->prep_rq_fn = pfn;
36}
Jens Axboe86db1e22008-01-29 14:53:40 +010037EXPORT_SYMBOL(blk_queue_prep_rq);
38
39/**
James Bottomley28018c22010-07-01 19:49:17 +090040 * blk_queue_unprep_rq - set an unprepare_request function for queue
41 * @q: queue
42 * @ufn: unprepare_request function
43 *
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.
48 *
49 */
50void blk_queue_unprep_rq(struct request_queue *q, unprep_rq_fn *ufn)
51{
52 q->unprep_rq_fn = ufn;
53}
54EXPORT_SYMBOL(blk_queue_unprep_rq);
55
Jens Axboe86db1e22008-01-29 14:53:40 +010056void blk_queue_softirq_done(struct request_queue *q, softirq_done_fn *fn)
57{
58 q->softirq_done_fn = fn;
59}
Jens Axboe86db1e22008-01-29 14:53:40 +010060EXPORT_SYMBOL(blk_queue_softirq_done);
61
Jens Axboe242f9dc2008-09-14 05:55:09 -070062void blk_queue_rq_timeout(struct request_queue *q, unsigned int timeout)
63{
64 q->rq_timeout = timeout;
65}
66EXPORT_SYMBOL_GPL(blk_queue_rq_timeout);
67
68void blk_queue_rq_timed_out(struct request_queue *q, rq_timed_out_fn *fn)
69{
70 q->rq_timed_out_fn = fn;
71}
72EXPORT_SYMBOL_GPL(blk_queue_rq_timed_out);
73
Kiyoshi Uedaef9e3fa2008-10-01 16:12:15 +020074void blk_queue_lld_busy(struct request_queue *q, lld_busy_fn *fn)
75{
76 q->lld_busy_fn = fn;
77}
78EXPORT_SYMBOL_GPL(blk_queue_lld_busy);
79
Jens Axboe86db1e22008-01-29 14:53:40 +010080/**
Martin K. Petersene475bba2009-06-16 08:23:52 +020081 * blk_set_default_limits - reset limits to default values
Randy Dunlapf740f5ca2009-06-19 09:18:32 +020082 * @lim: the queue_limits structure to reset
Martin K. Petersene475bba2009-06-16 08:23:52 +020083 *
84 * Description:
Martin K. Petersenb1bd0552012-01-11 16:27:11 +010085 * Returns a queue_limit struct to its default state.
Martin K. Petersene475bba2009-06-16 08:23:52 +020086 */
87void blk_set_default_limits(struct queue_limits *lim)
88{
Martin K. Petersen8a783622010-02-26 00:20:39 -050089 lim->max_segments = BLK_MAX_SEGMENTS;
Martin K. Petersen13f05c82010-09-10 20:50:10 +020090 lim->max_integrity_segments = 0;
Martin K. Petersene475bba2009-06-16 08:23:52 +020091 lim->seg_boundary_mask = BLK_SEG_BOUNDARY_MASK;
Keith Busch03100aa2015-08-19 14:24:05 -070092 lim->virt_boundary_mask = 0;
Martin K. Peterseneb28d312010-02-26 00:20:37 -050093 lim->max_segment_size = BLK_MAX_SEGMENT_SIZE;
Martin K. Petersenb1bd0552012-01-11 16:27:11 +010094 lim->max_sectors = lim->max_hw_sectors = BLK_SAFE_MAX_SECTORS;
Jens Axboe762380a2014-06-05 13:38:39 -060095 lim->chunk_sectors = 0;
Martin K. Petersen4363ac72012-09-18 12:19:27 -040096 lim->max_write_same_sectors = 0;
Martin K. Petersen86b37282009-11-10 11:50:21 +010097 lim->max_discard_sectors = 0;
Jens Axboe0034af02015-07-16 09:14:26 -060098 lim->max_hw_discard_sectors = 0;
Martin K. Petersen86b37282009-11-10 11:50:21 +010099 lim->discard_granularity = 0;
100 lim->discard_alignment = 0;
101 lim->discard_misaligned = 0;
Martin K. Petersenb1bd0552012-01-11 16:27:11 +0100102 lim->discard_zeroes_data = 0;
Martin K. Petersene475bba2009-06-16 08:23:52 +0200103 lim->logical_block_size = lim->physical_block_size = lim->io_min = 512;
Martin K. Petersen3a02c8e2009-06-18 09:56:03 +0200104 lim->bounce_pfn = (unsigned long)(BLK_BOUNCE_ANY >> PAGE_SHIFT);
Martin K. Petersene475bba2009-06-16 08:23:52 +0200105 lim->alignment_offset = 0;
106 lim->io_opt = 0;
107 lim->misaligned = 0;
Martin K. Petersene692cb62010-12-01 19:41:49 +0100108 lim->cluster = 1;
Martin K. Petersene475bba2009-06-16 08:23:52 +0200109}
110EXPORT_SYMBOL(blk_set_default_limits);
111
112/**
Martin K. Petersenb1bd0552012-01-11 16:27:11 +0100113 * blk_set_stacking_limits - set default limits for stacking devices
114 * @lim: the queue_limits structure to reset
115 *
116 * Description:
117 * Returns a queue_limit struct to its default state. Should be used
118 * by stacking drivers like DM that have no internal limits.
119 */
120void blk_set_stacking_limits(struct queue_limits *lim)
121{
122 blk_set_default_limits(lim);
123
124 /* Inherit limits from component devices */
125 lim->discard_zeroes_data = 1;
126 lim->max_segments = USHRT_MAX;
127 lim->max_hw_sectors = UINT_MAX;
Mike Snitzerd82ae522013-10-18 09:44:49 -0600128 lim->max_segment_size = UINT_MAX;
Mike Snitzerfe86cdc2012-08-01 10:44:28 +0200129 lim->max_sectors = UINT_MAX;
Martin K. Petersen4363ac72012-09-18 12:19:27 -0400130 lim->max_write_same_sectors = UINT_MAX;
Martin K. Petersenb1bd0552012-01-11 16:27:11 +0100131}
132EXPORT_SYMBOL(blk_set_stacking_limits);
133
134/**
Jens Axboe86db1e22008-01-29 14:53:40 +0100135 * blk_queue_make_request - define an alternate make_request function for a device
136 * @q: the request queue for the device to be affected
137 * @mfn: the alternate make_request function
138 *
139 * Description:
140 * The normal way for &struct bios to be passed to a device
141 * driver is for them to be collected into requests on a request
142 * queue, and then to allow the device driver to select requests
143 * off that queue when it is ready. This works well for many block
144 * devices. However some block devices (typically virtual devices
145 * such as md or lvm) do not benefit from the processing on the
146 * request queue, and are served best by having the requests passed
147 * directly to them. This can be achieved by providing a function
148 * to blk_queue_make_request().
149 *
150 * Caveat:
151 * The driver that does this *must* be able to deal appropriately
152 * with buffers in "highmemory". This can be accomplished by either calling
153 * __bio_kmap_atomic() to get a temporary kernel mapping, or by calling
154 * blk_queue_bounce() to create a buffer in normal memory.
155 **/
Jens Axboe6728cb02008-01-31 13:03:55 +0100156void blk_queue_make_request(struct request_queue *q, make_request_fn *mfn)
Jens Axboe86db1e22008-01-29 14:53:40 +0100157{
158 /*
159 * set defaults
160 */
161 q->nr_requests = BLKDEV_MAX_RQ;
Milan Broz0e435ac2008-12-03 12:55:08 +0100162
Jens Axboe86db1e22008-01-29 14:53:40 +0100163 q->make_request_fn = mfn;
Jens Axboe86db1e22008-01-29 14:53:40 +0100164 blk_queue_dma_alignment(q, 511);
165 blk_queue_congestion_threshold(q);
166 q->nr_batching = BLK_BATCH_REQ;
167
Martin K. Petersene475bba2009-06-16 08:23:52 +0200168 blk_set_default_limits(&q->limits);
169
Jens Axboe86db1e22008-01-29 14:53:40 +0100170 /*
171 * by default assume old behaviour and bounce for any highmem page
172 */
173 blk_queue_bounce_limit(q, BLK_BOUNCE_HIGH);
174}
Jens Axboe86db1e22008-01-29 14:53:40 +0100175EXPORT_SYMBOL(blk_queue_make_request);
176
177/**
178 * blk_queue_bounce_limit - set bounce buffer limit for queue
Tejun Heocd0aca22009-04-15 22:10:25 +0900179 * @q: the request queue for the device
Santosh Shilimkar9f7e45d2013-07-29 14:17:54 +0100180 * @max_addr: the maximum address the device can handle
Jens Axboe86db1e22008-01-29 14:53:40 +0100181 *
182 * Description:
183 * Different hardware can have different requirements as to what pages
184 * it can do I/O directly to. A low level driver can call
185 * blk_queue_bounce_limit to have lower memory pages allocated as bounce
Santosh Shilimkar9f7e45d2013-07-29 14:17:54 +0100186 * buffers for doing I/O to pages residing above @max_addr.
Jens Axboe86db1e22008-01-29 14:53:40 +0100187 **/
Santosh Shilimkar9f7e45d2013-07-29 14:17:54 +0100188void blk_queue_bounce_limit(struct request_queue *q, u64 max_addr)
Jens Axboe86db1e22008-01-29 14:53:40 +0100189{
Santosh Shilimkar9f7e45d2013-07-29 14:17:54 +0100190 unsigned long b_pfn = max_addr >> PAGE_SHIFT;
Jens Axboe86db1e22008-01-29 14:53:40 +0100191 int dma = 0;
192
193 q->bounce_gfp = GFP_NOIO;
194#if BITS_PER_LONG == 64
Tejun Heocd0aca22009-04-15 22:10:25 +0900195 /*
196 * Assume anything <= 4GB can be handled by IOMMU. Actually
197 * some IOMMUs can handle everything, but I don't know of a
198 * way to test this here.
199 */
200 if (b_pfn < (min_t(u64, 0xffffffffUL, BLK_BOUNCE_HIGH) >> PAGE_SHIFT))
Jens Axboe86db1e22008-01-29 14:53:40 +0100201 dma = 1;
Malahal Naineniefb012b2010-10-01 14:45:27 +0200202 q->limits.bounce_pfn = max(max_low_pfn, b_pfn);
Jens Axboe86db1e22008-01-29 14:53:40 +0100203#else
Jens Axboe6728cb02008-01-31 13:03:55 +0100204 if (b_pfn < blk_max_low_pfn)
Jens Axboe86db1e22008-01-29 14:53:40 +0100205 dma = 1;
Malahal Nainenic49825f2010-09-24 20:25:49 +0200206 q->limits.bounce_pfn = b_pfn;
Jens Axboe260a67a2010-10-01 14:42:43 +0200207#endif
Jens Axboe86db1e22008-01-29 14:53:40 +0100208 if (dma) {
209 init_emergency_isa_pool();
210 q->bounce_gfp = GFP_NOIO | GFP_DMA;
Jens Axboe260a67a2010-10-01 14:42:43 +0200211 q->limits.bounce_pfn = b_pfn;
Jens Axboe86db1e22008-01-29 14:53:40 +0100212 }
213}
Jens Axboe86db1e22008-01-29 14:53:40 +0100214EXPORT_SYMBOL(blk_queue_bounce_limit);
215
216/**
Mike Snitzer72d4cd92010-12-17 08:34:20 +0100217 * blk_limits_max_hw_sectors - set hard and soft limit of max sectors for request
218 * @limits: the queue limits
Martin K. Petersen2800aac2010-02-26 00:20:35 -0500219 * @max_hw_sectors: max hardware sectors in the usual 512b unit
Jens Axboe86db1e22008-01-29 14:53:40 +0100220 *
221 * Description:
Martin K. Petersen2800aac2010-02-26 00:20:35 -0500222 * Enables a low level driver to set a hard upper limit,
223 * max_hw_sectors, on the size of requests. max_hw_sectors is set by
Martin K. Petersen4f258a42015-06-23 12:13:59 -0400224 * the device driver based upon the capabilities of the I/O
225 * controller.
Martin K. Petersen2800aac2010-02-26 00:20:35 -0500226 *
227 * max_sectors is a soft limit imposed by the block layer for
228 * filesystem type requests. This value can be overridden on a
229 * per-device basis in /sys/block/<device>/queue/max_sectors_kb.
230 * The soft limit can not exceed max_hw_sectors.
Jens Axboe86db1e22008-01-29 14:53:40 +0100231 **/
Mike Snitzer72d4cd92010-12-17 08:34:20 +0100232void blk_limits_max_hw_sectors(struct queue_limits *limits, unsigned int max_hw_sectors)
Jens Axboe86db1e22008-01-29 14:53:40 +0100233{
Martin K. Petersen2800aac2010-02-26 00:20:35 -0500234 if ((max_hw_sectors << 9) < PAGE_CACHE_SIZE) {
235 max_hw_sectors = 1 << (PAGE_CACHE_SHIFT - 9);
Harvey Harrison24c03d42008-05-01 04:35:17 -0700236 printk(KERN_INFO "%s: set to minimum %d\n",
Martin K. Petersen2800aac2010-02-26 00:20:35 -0500237 __func__, max_hw_sectors);
Jens Axboe86db1e22008-01-29 14:53:40 +0100238 }
239
Jeff Moyer30e2bc02015-08-13 14:57:56 -0400240 limits->max_hw_sectors = max_hw_sectors;
241 limits->max_sectors = min_t(unsigned int, max_hw_sectors,
242 BLK_DEF_MAX_SECTORS);
Mike Snitzer72d4cd92010-12-17 08:34:20 +0100243}
244EXPORT_SYMBOL(blk_limits_max_hw_sectors);
245
246/**
247 * blk_queue_max_hw_sectors - set max sectors for a request for this queue
248 * @q: the request queue for the device
249 * @max_hw_sectors: max hardware sectors in the usual 512b unit
250 *
251 * Description:
252 * See description for blk_limits_max_hw_sectors().
253 **/
254void blk_queue_max_hw_sectors(struct request_queue *q, unsigned int max_hw_sectors)
255{
256 blk_limits_max_hw_sectors(&q->limits, max_hw_sectors);
Jens Axboe86db1e22008-01-29 14:53:40 +0100257}
Martin K. Petersen086fa5f2010-02-26 00:20:38 -0500258EXPORT_SYMBOL(blk_queue_max_hw_sectors);
Jens Axboe86db1e22008-01-29 14:53:40 +0100259
260/**
Jens Axboe762380a2014-06-05 13:38:39 -0600261 * blk_queue_chunk_sectors - set size of the chunk for this queue
262 * @q: the request queue for the device
263 * @chunk_sectors: chunk sectors in the usual 512b unit
264 *
265 * Description:
266 * If a driver doesn't want IOs to cross a given chunk size, it can set
267 * this limit and prevent merging across chunks. Note that the chunk size
Jens Axboe58a49152014-06-10 12:53:56 -0600268 * must currently be a power-of-2 in sectors. Also note that the block
269 * layer must accept a page worth of data at any offset. So if the
270 * crossing of chunks is a hard limitation in the driver, it must still be
271 * prepared to split single page bios.
Jens Axboe762380a2014-06-05 13:38:39 -0600272 **/
273void blk_queue_chunk_sectors(struct request_queue *q, unsigned int chunk_sectors)
274{
275 BUG_ON(!is_power_of_2(chunk_sectors));
276 q->limits.chunk_sectors = chunk_sectors;
277}
278EXPORT_SYMBOL(blk_queue_chunk_sectors);
279
280/**
Christoph Hellwig67efc922009-09-30 13:54:20 +0200281 * blk_queue_max_discard_sectors - set max sectors for a single discard
282 * @q: the request queue for the device
Randy Dunlapc7ebf062009-10-12 08:20:47 +0200283 * @max_discard_sectors: maximum number of sectors to discard
Christoph Hellwig67efc922009-09-30 13:54:20 +0200284 **/
285void blk_queue_max_discard_sectors(struct request_queue *q,
286 unsigned int max_discard_sectors)
287{
Jens Axboe0034af02015-07-16 09:14:26 -0600288 q->limits.max_hw_discard_sectors = max_discard_sectors;
Christoph Hellwig67efc922009-09-30 13:54:20 +0200289 q->limits.max_discard_sectors = max_discard_sectors;
290}
291EXPORT_SYMBOL(blk_queue_max_discard_sectors);
292
293/**
Martin K. Petersen4363ac72012-09-18 12:19:27 -0400294 * blk_queue_max_write_same_sectors - set max sectors for a single write same
295 * @q: the request queue for the device
296 * @max_write_same_sectors: maximum number of sectors to write per command
297 **/
298void blk_queue_max_write_same_sectors(struct request_queue *q,
299 unsigned int max_write_same_sectors)
300{
301 q->limits.max_write_same_sectors = max_write_same_sectors;
302}
303EXPORT_SYMBOL(blk_queue_max_write_same_sectors);
304
305/**
Martin K. Petersen8a783622010-02-26 00:20:39 -0500306 * blk_queue_max_segments - set max hw segments for a request for this queue
Jens Axboe86db1e22008-01-29 14:53:40 +0100307 * @q: the request queue for the device
308 * @max_segments: max number of segments
309 *
310 * Description:
311 * Enables a low level driver to set an upper limit on the number of
Martin K. Petersen8a783622010-02-26 00:20:39 -0500312 * hw data segments in a request.
Jens Axboe86db1e22008-01-29 14:53:40 +0100313 **/
Martin K. Petersen8a783622010-02-26 00:20:39 -0500314void blk_queue_max_segments(struct request_queue *q, unsigned short max_segments)
Jens Axboe86db1e22008-01-29 14:53:40 +0100315{
316 if (!max_segments) {
317 max_segments = 1;
Harvey Harrison24c03d42008-05-01 04:35:17 -0700318 printk(KERN_INFO "%s: set to minimum %d\n",
319 __func__, max_segments);
Jens Axboe86db1e22008-01-29 14:53:40 +0100320 }
321
Martin K. Petersen8a783622010-02-26 00:20:39 -0500322 q->limits.max_segments = max_segments;
Jens Axboe86db1e22008-01-29 14:53:40 +0100323}
Martin K. Petersen8a783622010-02-26 00:20:39 -0500324EXPORT_SYMBOL(blk_queue_max_segments);
Jens Axboe86db1e22008-01-29 14:53:40 +0100325
326/**
327 * blk_queue_max_segment_size - set max segment size for blk_rq_map_sg
328 * @q: the request queue for the device
329 * @max_size: max size of segment in bytes
330 *
331 * Description:
332 * Enables a low level driver to set an upper limit on the size of a
333 * coalesced segment
334 **/
335void blk_queue_max_segment_size(struct request_queue *q, unsigned int max_size)
336{
337 if (max_size < PAGE_CACHE_SIZE) {
338 max_size = PAGE_CACHE_SIZE;
Harvey Harrison24c03d42008-05-01 04:35:17 -0700339 printk(KERN_INFO "%s: set to minimum %d\n",
340 __func__, max_size);
Jens Axboe86db1e22008-01-29 14:53:40 +0100341 }
342
Martin K. Petersen025146e2009-05-22 17:17:51 -0400343 q->limits.max_segment_size = max_size;
Jens Axboe86db1e22008-01-29 14:53:40 +0100344}
Jens Axboe86db1e22008-01-29 14:53:40 +0100345EXPORT_SYMBOL(blk_queue_max_segment_size);
346
347/**
Martin K. Petersene1defc42009-05-22 17:17:49 -0400348 * blk_queue_logical_block_size - set logical block size for the queue
Jens Axboe86db1e22008-01-29 14:53:40 +0100349 * @q: the request queue for the device
Martin K. Petersene1defc42009-05-22 17:17:49 -0400350 * @size: the logical block size, in bytes
Jens Axboe86db1e22008-01-29 14:53:40 +0100351 *
352 * Description:
Martin K. Petersene1defc42009-05-22 17:17:49 -0400353 * This should be set to the lowest possible block size that the
354 * storage device can address. The default of 512 covers most
355 * hardware.
Jens Axboe86db1e22008-01-29 14:53:40 +0100356 **/
Martin K. Petersene1defc42009-05-22 17:17:49 -0400357void blk_queue_logical_block_size(struct request_queue *q, unsigned short size)
Jens Axboe86db1e22008-01-29 14:53:40 +0100358{
Martin K. Petersen025146e2009-05-22 17:17:51 -0400359 q->limits.logical_block_size = size;
Martin K. Petersenc72758f2009-05-22 17:17:53 -0400360
361 if (q->limits.physical_block_size < size)
362 q->limits.physical_block_size = size;
363
364 if (q->limits.io_min < q->limits.physical_block_size)
365 q->limits.io_min = q->limits.physical_block_size;
Jens Axboe86db1e22008-01-29 14:53:40 +0100366}
Martin K. Petersene1defc42009-05-22 17:17:49 -0400367EXPORT_SYMBOL(blk_queue_logical_block_size);
Jens Axboe86db1e22008-01-29 14:53:40 +0100368
Martin K. Petersenc72758f2009-05-22 17:17:53 -0400369/**
370 * blk_queue_physical_block_size - set physical block size for the queue
371 * @q: the request queue for the device
372 * @size: the physical block size, in bytes
373 *
374 * Description:
375 * This should be set to the lowest possible sector size that the
376 * hardware can operate on without reverting to read-modify-write
377 * operations.
378 */
Martin K. Petersen892b6f92010-10-13 21:18:03 +0200379void blk_queue_physical_block_size(struct request_queue *q, unsigned int size)
Martin K. Petersenc72758f2009-05-22 17:17:53 -0400380{
381 q->limits.physical_block_size = size;
382
383 if (q->limits.physical_block_size < q->limits.logical_block_size)
384 q->limits.physical_block_size = q->limits.logical_block_size;
385
386 if (q->limits.io_min < q->limits.physical_block_size)
387 q->limits.io_min = q->limits.physical_block_size;
388}
389EXPORT_SYMBOL(blk_queue_physical_block_size);
390
391/**
392 * blk_queue_alignment_offset - set physical block alignment offset
393 * @q: the request queue for the device
Randy Dunlap8ebf9752009-06-11 20:00:41 -0700394 * @offset: alignment offset in bytes
Martin K. Petersenc72758f2009-05-22 17:17:53 -0400395 *
396 * Description:
397 * Some devices are naturally misaligned to compensate for things like
398 * the legacy DOS partition table 63-sector offset. Low-level drivers
399 * should call this function for devices whose first sector is not
400 * naturally aligned.
401 */
402void blk_queue_alignment_offset(struct request_queue *q, unsigned int offset)
403{
404 q->limits.alignment_offset =
405 offset & (q->limits.physical_block_size - 1);
406 q->limits.misaligned = 0;
407}
408EXPORT_SYMBOL(blk_queue_alignment_offset);
409
410/**
Martin K. Petersen7c958e32009-07-31 11:49:11 -0400411 * blk_limits_io_min - set minimum request size for a device
412 * @limits: the queue limits
413 * @min: smallest I/O size in bytes
414 *
415 * Description:
416 * Some devices have an internal block size bigger than the reported
417 * hardware sector size. This function can be used to signal the
418 * smallest I/O the device can perform without incurring a performance
419 * penalty.
420 */
421void blk_limits_io_min(struct queue_limits *limits, unsigned int min)
422{
423 limits->io_min = min;
424
425 if (limits->io_min < limits->logical_block_size)
426 limits->io_min = limits->logical_block_size;
427
428 if (limits->io_min < limits->physical_block_size)
429 limits->io_min = limits->physical_block_size;
430}
431EXPORT_SYMBOL(blk_limits_io_min);
432
433/**
Martin K. Petersenc72758f2009-05-22 17:17:53 -0400434 * blk_queue_io_min - set minimum request size for the queue
435 * @q: the request queue for the device
Randy Dunlap8ebf9752009-06-11 20:00:41 -0700436 * @min: smallest I/O size in bytes
Martin K. Petersenc72758f2009-05-22 17:17:53 -0400437 *
438 * Description:
Martin K. Petersen7e5f5fb2009-07-31 11:49:13 -0400439 * Storage devices may report a granularity or preferred minimum I/O
440 * size which is the smallest request the device can perform without
441 * incurring a performance penalty. For disk drives this is often the
442 * physical block size. For RAID arrays it is often the stripe chunk
443 * size. A properly aligned multiple of minimum_io_size is the
444 * preferred request size for workloads where a high number of I/O
445 * operations is desired.
Martin K. Petersenc72758f2009-05-22 17:17:53 -0400446 */
447void blk_queue_io_min(struct request_queue *q, unsigned int min)
448{
Martin K. Petersen7c958e32009-07-31 11:49:11 -0400449 blk_limits_io_min(&q->limits, min);
Martin K. Petersenc72758f2009-05-22 17:17:53 -0400450}
451EXPORT_SYMBOL(blk_queue_io_min);
452
453/**
Martin K. Petersen3c5820c2009-09-11 21:54:52 +0200454 * blk_limits_io_opt - set optimal request size for a device
455 * @limits: the queue limits
456 * @opt: smallest I/O size in bytes
457 *
458 * Description:
459 * Storage devices may report an optimal I/O size, which is the
460 * device's preferred unit for sustained I/O. This is rarely reported
461 * for disk drives. For RAID arrays it is usually the stripe width or
462 * the internal track size. A properly aligned multiple of
463 * optimal_io_size is the preferred request size for workloads where
464 * sustained throughput is desired.
465 */
466void blk_limits_io_opt(struct queue_limits *limits, unsigned int opt)
467{
468 limits->io_opt = opt;
469}
470EXPORT_SYMBOL(blk_limits_io_opt);
471
472/**
Martin K. Petersenc72758f2009-05-22 17:17:53 -0400473 * blk_queue_io_opt - set optimal request size for the queue
474 * @q: the request queue for the device
Randy Dunlap8ebf9752009-06-11 20:00:41 -0700475 * @opt: optimal request size in bytes
Martin K. Petersenc72758f2009-05-22 17:17:53 -0400476 *
477 * Description:
Martin K. Petersen7e5f5fb2009-07-31 11:49:13 -0400478 * Storage devices may report an optimal I/O size, which is the
479 * device's preferred unit for sustained I/O. This is rarely reported
480 * for disk drives. For RAID arrays it is usually the stripe width or
481 * the internal track size. A properly aligned multiple of
482 * optimal_io_size is the preferred request size for workloads where
483 * sustained throughput is desired.
Martin K. Petersenc72758f2009-05-22 17:17:53 -0400484 */
485void blk_queue_io_opt(struct request_queue *q, unsigned int opt)
486{
Martin K. Petersen3c5820c2009-09-11 21:54:52 +0200487 blk_limits_io_opt(&q->limits, opt);
Martin K. Petersenc72758f2009-05-22 17:17:53 -0400488}
489EXPORT_SYMBOL(blk_queue_io_opt);
490
Jens Axboe86db1e22008-01-29 14:53:40 +0100491/**
492 * blk_queue_stack_limits - inherit underlying queue limits for stacked drivers
493 * @t: the stacking driver (top)
494 * @b: the underlying device (bottom)
495 **/
496void blk_queue_stack_limits(struct request_queue *t, struct request_queue *b)
497{
Martin K. Petersenfef24662009-07-31 11:49:10 -0400498 blk_stack_limits(&t->limits, &b->limits, 0);
Jens Axboe86db1e22008-01-29 14:53:40 +0100499}
Jens Axboe86db1e22008-01-29 14:53:40 +0100500EXPORT_SYMBOL(blk_queue_stack_limits);
501
502/**
Martin K. Petersenc72758f2009-05-22 17:17:53 -0400503 * blk_stack_limits - adjust queue_limits for stacked devices
Martin K. Petersen81744ee2009-12-29 08:35:35 +0100504 * @t: the stacking driver limits (top device)
505 * @b: the underlying queue limits (bottom, component device)
Martin K. Petersene03a72e2010-01-11 03:21:51 -0500506 * @start: first data sector within component device
Martin K. Petersenc72758f2009-05-22 17:17:53 -0400507 *
508 * Description:
Martin K. Petersen81744ee2009-12-29 08:35:35 +0100509 * This function is used by stacking drivers like MD and DM to ensure
510 * that all component devices have compatible block sizes and
511 * alignments. The stacking driver must provide a queue_limits
512 * struct (top) and then iteratively call the stacking function for
513 * all component (bottom) devices. The stacking function will
514 * attempt to combine the values and ensure proper alignment.
515 *
516 * Returns 0 if the top and bottom queue_limits are compatible. The
517 * top device's block sizes and alignment offsets may be adjusted to
518 * ensure alignment with the bottom device. If no compatible sizes
519 * and alignments exist, -1 is returned and the resulting top
520 * queue_limits will have the misaligned flag set to indicate that
521 * the alignment_offset is undefined.
Martin K. Petersenc72758f2009-05-22 17:17:53 -0400522 */
523int blk_stack_limits(struct queue_limits *t, struct queue_limits *b,
Martin K. Petersene03a72e2010-01-11 03:21:51 -0500524 sector_t start)
Martin K. Petersenc72758f2009-05-22 17:17:53 -0400525{
Martin K. Petersene03a72e2010-01-11 03:21:51 -0500526 unsigned int top, bottom, alignment, ret = 0;
Martin K. Petersen86b37282009-11-10 11:50:21 +0100527
Martin K. Petersenc72758f2009-05-22 17:17:53 -0400528 t->max_sectors = min_not_zero(t->max_sectors, b->max_sectors);
529 t->max_hw_sectors = min_not_zero(t->max_hw_sectors, b->max_hw_sectors);
Martin K. Petersen4363ac72012-09-18 12:19:27 -0400530 t->max_write_same_sectors = min(t->max_write_same_sectors,
531 b->max_write_same_sectors);
Martin K. Petersen77634f32009-06-09 06:23:22 +0200532 t->bounce_pfn = min_not_zero(t->bounce_pfn, b->bounce_pfn);
Martin K. Petersenc72758f2009-05-22 17:17:53 -0400533
534 t->seg_boundary_mask = min_not_zero(t->seg_boundary_mask,
535 b->seg_boundary_mask);
Keith Busch03100aa2015-08-19 14:24:05 -0700536 t->virt_boundary_mask = min_not_zero(t->virt_boundary_mask,
537 b->virt_boundary_mask);
Martin K. Petersenc72758f2009-05-22 17:17:53 -0400538
Martin K. Petersen8a783622010-02-26 00:20:39 -0500539 t->max_segments = min_not_zero(t->max_segments, b->max_segments);
Martin K. Petersen13f05c82010-09-10 20:50:10 +0200540 t->max_integrity_segments = min_not_zero(t->max_integrity_segments,
541 b->max_integrity_segments);
Martin K. Petersenc72758f2009-05-22 17:17:53 -0400542
543 t->max_segment_size = min_not_zero(t->max_segment_size,
544 b->max_segment_size);
545
Martin K. Petersenfe0b3932010-01-11 03:21:47 -0500546 t->misaligned |= b->misaligned;
547
Martin K. Petersene03a72e2010-01-11 03:21:51 -0500548 alignment = queue_limit_alignment_offset(b, start);
Martin K. Petersen9504e082009-12-21 15:55:51 +0100549
Martin K. Petersen81744ee2009-12-29 08:35:35 +0100550 /* Bottom device has different alignment. Check that it is
551 * compatible with the current top alignment.
552 */
Martin K. Petersen9504e082009-12-21 15:55:51 +0100553 if (t->alignment_offset != alignment) {
554
555 top = max(t->physical_block_size, t->io_min)
556 + t->alignment_offset;
Martin K. Petersen81744ee2009-12-29 08:35:35 +0100557 bottom = max(b->physical_block_size, b->io_min) + alignment;
Martin K. Petersen9504e082009-12-21 15:55:51 +0100558
Martin K. Petersen81744ee2009-12-29 08:35:35 +0100559 /* Verify that top and bottom intervals line up */
Mike Snitzerb8839b82014-10-08 18:26:13 -0400560 if (max(top, bottom) % min(top, bottom)) {
Martin K. Petersen9504e082009-12-21 15:55:51 +0100561 t->misaligned = 1;
Martin K. Petersenfe0b3932010-01-11 03:21:47 -0500562 ret = -1;
563 }
Martin K. Petersen9504e082009-12-21 15:55:51 +0100564 }
565
Martin K. Petersenc72758f2009-05-22 17:17:53 -0400566 t->logical_block_size = max(t->logical_block_size,
567 b->logical_block_size);
568
569 t->physical_block_size = max(t->physical_block_size,
570 b->physical_block_size);
571
572 t->io_min = max(t->io_min, b->io_min);
Mike Snitzere9637412015-03-30 13:39:09 -0400573 t->io_opt = lcm_not_zero(t->io_opt, b->io_opt);
Martin K. Petersen9504e082009-12-21 15:55:51 +0100574
Martin K. Petersene692cb62010-12-01 19:41:49 +0100575 t->cluster &= b->cluster;
Martin K. Petersen98262f22009-12-03 09:24:48 +0100576 t->discard_zeroes_data &= b->discard_zeroes_data;
Martin K. Petersenc72758f2009-05-22 17:17:53 -0400577
Martin K. Petersen81744ee2009-12-29 08:35:35 +0100578 /* Physical block size a multiple of the logical block size? */
Martin K. Petersen9504e082009-12-21 15:55:51 +0100579 if (t->physical_block_size & (t->logical_block_size - 1)) {
580 t->physical_block_size = t->logical_block_size;
Martin K. Petersenc72758f2009-05-22 17:17:53 -0400581 t->misaligned = 1;
Martin K. Petersenfe0b3932010-01-11 03:21:47 -0500582 ret = -1;
Martin K. Petersen86b37282009-11-10 11:50:21 +0100583 }
584
Martin K. Petersen81744ee2009-12-29 08:35:35 +0100585 /* Minimum I/O a multiple of the physical block size? */
Martin K. Petersen9504e082009-12-21 15:55:51 +0100586 if (t->io_min & (t->physical_block_size - 1)) {
587 t->io_min = t->physical_block_size;
Martin K. Petersenc72758f2009-05-22 17:17:53 -0400588 t->misaligned = 1;
Martin K. Petersenfe0b3932010-01-11 03:21:47 -0500589 ret = -1;
Martin K. Petersenc72758f2009-05-22 17:17:53 -0400590 }
591
Martin K. Petersen81744ee2009-12-29 08:35:35 +0100592 /* Optimal I/O a multiple of the physical block size? */
Martin K. Petersen9504e082009-12-21 15:55:51 +0100593 if (t->io_opt & (t->physical_block_size - 1)) {
594 t->io_opt = 0;
595 t->misaligned = 1;
Martin K. Petersenfe0b3932010-01-11 03:21:47 -0500596 ret = -1;
Martin K. Petersen9504e082009-12-21 15:55:51 +0100597 }
Martin K. Petersen70dd5bf2009-07-31 11:49:12 -0400598
Kent Overstreetc78afc62013-07-11 22:39:53 -0700599 t->raid_partial_stripes_expensive =
600 max(t->raid_partial_stripes_expensive,
601 b->raid_partial_stripes_expensive);
602
Martin K. Petersen81744ee2009-12-29 08:35:35 +0100603 /* Find lowest common alignment_offset */
Mike Snitzere9637412015-03-30 13:39:09 -0400604 t->alignment_offset = lcm_not_zero(t->alignment_offset, alignment)
Mike Snitzerb8839b82014-10-08 18:26:13 -0400605 % max(t->physical_block_size, t->io_min);
Martin K. Petersen70dd5bf2009-07-31 11:49:12 -0400606
Martin K. Petersen81744ee2009-12-29 08:35:35 +0100607 /* Verify that new alignment_offset is on a logical block boundary */
Martin K. Petersenfe0b3932010-01-11 03:21:47 -0500608 if (t->alignment_offset & (t->logical_block_size - 1)) {
Martin K. Petersen9504e082009-12-21 15:55:51 +0100609 t->misaligned = 1;
Martin K. Petersenfe0b3932010-01-11 03:21:47 -0500610 ret = -1;
611 }
Martin K. Petersen9504e082009-12-21 15:55:51 +0100612
613 /* Discard alignment and granularity */
614 if (b->discard_granularity) {
Martin K. Petersene03a72e2010-01-11 03:21:51 -0500615 alignment = queue_limit_discard_alignment(b, start);
Martin K. Petersen9504e082009-12-21 15:55:51 +0100616
617 if (t->discard_granularity != 0 &&
618 t->discard_alignment != alignment) {
619 top = t->discard_granularity + t->discard_alignment;
620 bottom = b->discard_granularity + alignment;
621
622 /* Verify that top and bottom intervals line up */
Shaohua Li8dd2cb72012-12-14 11:15:36 +0800623 if ((max(top, bottom) % min(top, bottom)) != 0)
Martin K. Petersen9504e082009-12-21 15:55:51 +0100624 t->discard_misaligned = 1;
625 }
626
Martin K. Petersen81744ee2009-12-29 08:35:35 +0100627 t->max_discard_sectors = min_not_zero(t->max_discard_sectors,
628 b->max_discard_sectors);
Jens Axboe0034af02015-07-16 09:14:26 -0600629 t->max_hw_discard_sectors = min_not_zero(t->max_hw_discard_sectors,
630 b->max_hw_discard_sectors);
Martin K. Petersen9504e082009-12-21 15:55:51 +0100631 t->discard_granularity = max(t->discard_granularity,
632 b->discard_granularity);
Mike Snitzere9637412015-03-30 13:39:09 -0400633 t->discard_alignment = lcm_not_zero(t->discard_alignment, alignment) %
Shaohua Li8dd2cb72012-12-14 11:15:36 +0800634 t->discard_granularity;
Martin K. Petersen9504e082009-12-21 15:55:51 +0100635 }
636
Martin K. Petersenfe0b3932010-01-11 03:21:47 -0500637 return ret;
Martin K. Petersenc72758f2009-05-22 17:17:53 -0400638}
Mike Snitzer5d85d322009-05-28 11:04:53 +0200639EXPORT_SYMBOL(blk_stack_limits);
Martin K. Petersenc72758f2009-05-22 17:17:53 -0400640
641/**
Martin K. Petersen17be8c22010-01-11 03:21:49 -0500642 * bdev_stack_limits - adjust queue limits for stacked drivers
643 * @t: the stacking driver limits (top device)
644 * @bdev: the component block_device (bottom)
645 * @start: first data sector within component device
646 *
647 * Description:
648 * Merges queue limits for a top device and a block_device. Returns
649 * 0 if alignment didn't change. Returns -1 if adding the bottom
650 * device caused misalignment.
651 */
652int bdev_stack_limits(struct queue_limits *t, struct block_device *bdev,
653 sector_t start)
654{
655 struct request_queue *bq = bdev_get_queue(bdev);
656
657 start += get_start_sect(bdev);
658
Martin K. Petersene03a72e2010-01-11 03:21:51 -0500659 return blk_stack_limits(t, &bq->limits, start);
Martin K. Petersen17be8c22010-01-11 03:21:49 -0500660}
661EXPORT_SYMBOL(bdev_stack_limits);
662
663/**
Martin K. Petersenc72758f2009-05-22 17:17:53 -0400664 * disk_stack_limits - adjust queue limits for stacked drivers
Martin K. Petersen77634f32009-06-09 06:23:22 +0200665 * @disk: MD/DM gendisk (top)
Martin K. Petersenc72758f2009-05-22 17:17:53 -0400666 * @bdev: the underlying block device (bottom)
667 * @offset: offset to beginning of data within component device
668 *
669 * Description:
Martin K. Petersene03a72e2010-01-11 03:21:51 -0500670 * Merges the limits for a top level gendisk and a bottom level
671 * block_device.
Martin K. Petersenc72758f2009-05-22 17:17:53 -0400672 */
673void disk_stack_limits(struct gendisk *disk, struct block_device *bdev,
674 sector_t offset)
675{
676 struct request_queue *t = disk->queue;
Martin K. Petersenc72758f2009-05-22 17:17:53 -0400677
Martin K. Petersene03a72e2010-01-11 03:21:51 -0500678 if (bdev_stack_limits(&t->limits, bdev, offset >> 9) < 0) {
Martin K. Petersenc72758f2009-05-22 17:17:53 -0400679 char top[BDEVNAME_SIZE], bottom[BDEVNAME_SIZE];
680
681 disk_name(disk, 0, top);
682 bdevname(bdev, bottom);
683
684 printk(KERN_NOTICE "%s: Warning: Device %s is misaligned\n",
685 top, bottom);
686 }
Martin K. Petersenc72758f2009-05-22 17:17:53 -0400687}
688EXPORT_SYMBOL(disk_stack_limits);
689
690/**
Tejun Heoe3790c72008-03-04 11:18:17 +0100691 * blk_queue_dma_pad - set pad mask
692 * @q: the request queue for the device
693 * @mask: pad mask
694 *
FUJITA Tomonori27f82212008-07-04 09:30:03 +0200695 * Set dma pad mask.
Tejun Heoe3790c72008-03-04 11:18:17 +0100696 *
FUJITA Tomonori27f82212008-07-04 09:30:03 +0200697 * Appending pad buffer to a request modifies the last entry of a
698 * scatter list such that it includes the pad buffer.
Tejun Heoe3790c72008-03-04 11:18:17 +0100699 **/
700void blk_queue_dma_pad(struct request_queue *q, unsigned int mask)
701{
702 q->dma_pad_mask = mask;
703}
704EXPORT_SYMBOL(blk_queue_dma_pad);
705
706/**
FUJITA Tomonori27f82212008-07-04 09:30:03 +0200707 * blk_queue_update_dma_pad - update pad mask
708 * @q: the request queue for the device
709 * @mask: pad mask
710 *
711 * Update dma pad mask.
712 *
713 * Appending pad buffer to a request modifies the last entry of a
714 * scatter list such that it includes the pad buffer.
715 **/
716void blk_queue_update_dma_pad(struct request_queue *q, unsigned int mask)
717{
718 if (mask > q->dma_pad_mask)
719 q->dma_pad_mask = mask;
720}
721EXPORT_SYMBOL(blk_queue_update_dma_pad);
722
723/**
Jens Axboe86db1e22008-01-29 14:53:40 +0100724 * blk_queue_dma_drain - Set up a drain buffer for excess dma.
Jens Axboe86db1e22008-01-29 14:53:40 +0100725 * @q: the request queue for the device
Tejun Heo2fb98e82008-02-19 11:36:53 +0100726 * @dma_drain_needed: fn which returns non-zero if drain is necessary
Jens Axboe86db1e22008-01-29 14:53:40 +0100727 * @buf: physically contiguous buffer
728 * @size: size of the buffer in bytes
729 *
730 * Some devices have excess DMA problems and can't simply discard (or
731 * zero fill) the unwanted piece of the transfer. They have to have a
732 * real area of memory to transfer it into. The use case for this is
733 * ATAPI devices in DMA mode. If the packet command causes a transfer
734 * bigger than the transfer size some HBAs will lock up if there
735 * aren't DMA elements to contain the excess transfer. What this API
736 * does is adjust the queue so that the buf is always appended
737 * silently to the scatterlist.
738 *
Martin K. Petersen8a783622010-02-26 00:20:39 -0500739 * Note: This routine adjusts max_hw_segments to make room for appending
740 * the drain buffer. If you call blk_queue_max_segments() after calling
741 * this routine, you must set the limit to one fewer than your device
742 * can support otherwise there won't be room for the drain buffer.
Jens Axboe86db1e22008-01-29 14:53:40 +0100743 */
Harvey Harrison448da4d2008-03-04 11:30:18 +0100744int blk_queue_dma_drain(struct request_queue *q,
Tejun Heo2fb98e82008-02-19 11:36:53 +0100745 dma_drain_needed_fn *dma_drain_needed,
746 void *buf, unsigned int size)
Jens Axboe86db1e22008-01-29 14:53:40 +0100747{
Martin K. Petersen8a783622010-02-26 00:20:39 -0500748 if (queue_max_segments(q) < 2)
Jens Axboe86db1e22008-01-29 14:53:40 +0100749 return -EINVAL;
750 /* make room for appending the drain */
Martin K. Petersen8a783622010-02-26 00:20:39 -0500751 blk_queue_max_segments(q, queue_max_segments(q) - 1);
Tejun Heo2fb98e82008-02-19 11:36:53 +0100752 q->dma_drain_needed = dma_drain_needed;
Jens Axboe86db1e22008-01-29 14:53:40 +0100753 q->dma_drain_buffer = buf;
754 q->dma_drain_size = size;
755
756 return 0;
757}
Jens Axboe86db1e22008-01-29 14:53:40 +0100758EXPORT_SYMBOL_GPL(blk_queue_dma_drain);
759
760/**
761 * blk_queue_segment_boundary - set boundary rules for segment merging
762 * @q: the request queue for the device
763 * @mask: the memory boundary mask
764 **/
765void blk_queue_segment_boundary(struct request_queue *q, unsigned long mask)
766{
767 if (mask < PAGE_CACHE_SIZE - 1) {
768 mask = PAGE_CACHE_SIZE - 1;
Harvey Harrison24c03d42008-05-01 04:35:17 -0700769 printk(KERN_INFO "%s: set to minimum %lx\n",
770 __func__, mask);
Jens Axboe86db1e22008-01-29 14:53:40 +0100771 }
772
Martin K. Petersen025146e2009-05-22 17:17:51 -0400773 q->limits.seg_boundary_mask = mask;
Jens Axboe86db1e22008-01-29 14:53:40 +0100774}
Jens Axboe86db1e22008-01-29 14:53:40 +0100775EXPORT_SYMBOL(blk_queue_segment_boundary);
776
777/**
Keith Busch03100aa2015-08-19 14:24:05 -0700778 * blk_queue_virt_boundary - set boundary rules for bio merging
779 * @q: the request queue for the device
780 * @mask: the memory boundary mask
781 **/
782void blk_queue_virt_boundary(struct request_queue *q, unsigned long mask)
783{
784 q->limits.virt_boundary_mask = mask;
785}
786EXPORT_SYMBOL(blk_queue_virt_boundary);
787
788/**
Jens Axboe86db1e22008-01-29 14:53:40 +0100789 * blk_queue_dma_alignment - set dma length and memory alignment
790 * @q: the request queue for the device
791 * @mask: alignment mask
792 *
793 * description:
Randy Dunlap710027a2008-08-19 20:13:11 +0200794 * set required memory and length alignment for direct dma transactions.
Alan Cox8feb4d22009-04-01 15:01:39 +0100795 * this is used when building direct io requests for the queue.
Jens Axboe86db1e22008-01-29 14:53:40 +0100796 *
797 **/
798void blk_queue_dma_alignment(struct request_queue *q, int mask)
799{
800 q->dma_alignment = mask;
801}
Jens Axboe86db1e22008-01-29 14:53:40 +0100802EXPORT_SYMBOL(blk_queue_dma_alignment);
803
804/**
805 * blk_queue_update_dma_alignment - update dma length and memory alignment
806 * @q: the request queue for the device
807 * @mask: alignment mask
808 *
809 * description:
Randy Dunlap710027a2008-08-19 20:13:11 +0200810 * update required memory and length alignment for direct dma transactions.
Jens Axboe86db1e22008-01-29 14:53:40 +0100811 * If the requested alignment is larger than the current alignment, then
812 * the current queue alignment is updated to the new value, otherwise it
813 * is left alone. The design of this is to allow multiple objects
814 * (driver, device, transport etc) to set their respective
815 * alignments without having them interfere.
816 *
817 **/
818void blk_queue_update_dma_alignment(struct request_queue *q, int mask)
819{
820 BUG_ON(mask > PAGE_SIZE);
821
822 if (mask > q->dma_alignment)
823 q->dma_alignment = mask;
824}
Jens Axboe86db1e22008-01-29 14:53:40 +0100825EXPORT_SYMBOL(blk_queue_update_dma_alignment);
826
Tejun Heo4913efe2010-09-03 11:56:16 +0200827/**
828 * blk_queue_flush - configure queue's cache flush capability
829 * @q: the request queue for the device
830 * @flush: 0, REQ_FLUSH or REQ_FLUSH | REQ_FUA
831 *
832 * Tell block layer cache flush capability of @q. If it supports
833 * flushing, REQ_FLUSH should be set. If it supports bypassing
834 * write cache for individual writes, REQ_FUA should be set.
835 */
836void blk_queue_flush(struct request_queue *q, unsigned int flush)
837{
838 WARN_ON_ONCE(flush & ~(REQ_FLUSH | REQ_FUA));
839
840 if (WARN_ON_ONCE(!(flush & REQ_FLUSH) && (flush & REQ_FUA)))
841 flush &= ~REQ_FUA;
842
843 q->flush_flags = flush & (REQ_FLUSH | REQ_FUA);
844}
845EXPORT_SYMBOL_GPL(blk_queue_flush);
846
shaohua.li@intel.comf3876932011-05-06 11:34:32 -0600847void blk_queue_flush_queueable(struct request_queue *q, bool queueable)
848{
849 q->flush_not_queueable = !queueable;
850}
851EXPORT_SYMBOL_GPL(blk_queue_flush_queueable);
852
Harvey Harrisonaeb3d3a2008-08-28 09:27:42 +0200853static int __init blk_settings_init(void)
Jens Axboe86db1e22008-01-29 14:53:40 +0100854{
855 blk_max_low_pfn = max_low_pfn - 1;
856 blk_max_pfn = max_pfn - 1;
857 return 0;
858}
859subsys_initcall(blk_settings_init);