blob: e0057d035200c4dd5e42d191f0395a7769489905 [file] [log] [blame]
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
56/**
Jens Axboe86db1e22008-01-29 14:53:40 +010057 * blk_queue_merge_bvec - set a merge_bvec function for queue
58 * @q: queue
59 * @mbfn: merge_bvec_fn
60 *
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
70 * honored.
71 */
72void blk_queue_merge_bvec(struct request_queue *q, merge_bvec_fn *mbfn)
73{
74 q->merge_bvec_fn = mbfn;
75}
Jens Axboe86db1e22008-01-29 14:53:40 +010076EXPORT_SYMBOL(blk_queue_merge_bvec);
77
78void blk_queue_softirq_done(struct request_queue *q, softirq_done_fn *fn)
79{
80 q->softirq_done_fn = fn;
81}
Jens Axboe86db1e22008-01-29 14:53:40 +010082EXPORT_SYMBOL(blk_queue_softirq_done);
83
Jens Axboe242f9dc2008-09-14 05:55:09 -070084void blk_queue_rq_timeout(struct request_queue *q, unsigned int timeout)
85{
86 q->rq_timeout = timeout;
87}
88EXPORT_SYMBOL_GPL(blk_queue_rq_timeout);
89
90void blk_queue_rq_timed_out(struct request_queue *q, rq_timed_out_fn *fn)
91{
92 q->rq_timed_out_fn = fn;
93}
94EXPORT_SYMBOL_GPL(blk_queue_rq_timed_out);
95
Kiyoshi Uedaef9e3fa2008-10-01 16:12:15 +020096void blk_queue_lld_busy(struct request_queue *q, lld_busy_fn *fn)
97{
98 q->lld_busy_fn = fn;
99}
100EXPORT_SYMBOL_GPL(blk_queue_lld_busy);
101
Jens Axboe86db1e22008-01-29 14:53:40 +0100102/**
Martin K. Petersene475bba2009-06-16 08:23:52 +0200103 * blk_set_default_limits - reset limits to default values
Randy Dunlapf740f5ca2009-06-19 09:18:32 +0200104 * @lim: the queue_limits structure to reset
Martin K. Petersene475bba2009-06-16 08:23:52 +0200105 *
106 * Description:
Martin K. Petersenb1bd0552012-01-11 16:27:11 +0100107 * Returns a queue_limit struct to its default state.
Martin K. Petersene475bba2009-06-16 08:23:52 +0200108 */
109void blk_set_default_limits(struct queue_limits *lim)
110{
Martin K. Petersen8a783622010-02-26 00:20:39 -0500111 lim->max_segments = BLK_MAX_SEGMENTS;
Martin K. Petersen13f05c82010-09-10 20:50:10 +0200112 lim->max_integrity_segments = 0;
Martin K. Petersene475bba2009-06-16 08:23:52 +0200113 lim->seg_boundary_mask = BLK_SEG_BOUNDARY_MASK;
Martin K. Peterseneb28d312010-02-26 00:20:37 -0500114 lim->max_segment_size = BLK_MAX_SEGMENT_SIZE;
Martin K. Petersenb1bd0552012-01-11 16:27:11 +0100115 lim->max_sectors = lim->max_hw_sectors = BLK_SAFE_MAX_SECTORS;
Jens Axboe762380a2014-06-05 13:38:39 -0600116 lim->chunk_sectors = 0;
Martin K. Petersen4363ac72012-09-18 12:19:27 -0400117 lim->max_write_same_sectors = 0;
Martin K. Petersen86b37282009-11-10 11:50:21 +0100118 lim->max_discard_sectors = 0;
119 lim->discard_granularity = 0;
120 lim->discard_alignment = 0;
121 lim->discard_misaligned = 0;
Martin K. Petersenb1bd0552012-01-11 16:27:11 +0100122 lim->discard_zeroes_data = 0;
Martin K. Petersene475bba2009-06-16 08:23:52 +0200123 lim->logical_block_size = lim->physical_block_size = lim->io_min = 512;
Martin K. Petersen3a02c8e2009-06-18 09:56:03 +0200124 lim->bounce_pfn = (unsigned long)(BLK_BOUNCE_ANY >> PAGE_SHIFT);
Martin K. Petersene475bba2009-06-16 08:23:52 +0200125 lim->alignment_offset = 0;
126 lim->io_opt = 0;
127 lim->misaligned = 0;
Martin K. Petersene692cb62010-12-01 19:41:49 +0100128 lim->cluster = 1;
Martin K. Petersene475bba2009-06-16 08:23:52 +0200129}
130EXPORT_SYMBOL(blk_set_default_limits);
131
132/**
Martin K. Petersenb1bd0552012-01-11 16:27:11 +0100133 * blk_set_stacking_limits - set default limits for stacking devices
134 * @lim: the queue_limits structure to reset
135 *
136 * Description:
137 * Returns a queue_limit struct to its default state. Should be used
138 * by stacking drivers like DM that have no internal limits.
139 */
140void blk_set_stacking_limits(struct queue_limits *lim)
141{
142 blk_set_default_limits(lim);
143
144 /* Inherit limits from component devices */
145 lim->discard_zeroes_data = 1;
146 lim->max_segments = USHRT_MAX;
147 lim->max_hw_sectors = UINT_MAX;
Mike Snitzerd82ae522013-10-18 09:44:49 -0600148 lim->max_segment_size = UINT_MAX;
Mike Snitzerfe86cdc2012-08-01 10:44:28 +0200149 lim->max_sectors = UINT_MAX;
Martin K. Petersen4363ac72012-09-18 12:19:27 -0400150 lim->max_write_same_sectors = UINT_MAX;
Martin K. Petersenb1bd0552012-01-11 16:27:11 +0100151}
152EXPORT_SYMBOL(blk_set_stacking_limits);
153
154/**
Jens Axboe86db1e22008-01-29 14:53:40 +0100155 * blk_queue_make_request - define an alternate make_request function for a device
156 * @q: the request queue for the device to be affected
157 * @mfn: the alternate make_request function
158 *
159 * Description:
160 * The normal way for &struct bios to be passed to a device
161 * driver is for them to be collected into requests on a request
162 * queue, and then to allow the device driver to select requests
163 * off that queue when it is ready. This works well for many block
164 * devices. However some block devices (typically virtual devices
165 * such as md or lvm) do not benefit from the processing on the
166 * request queue, and are served best by having the requests passed
167 * directly to them. This can be achieved by providing a function
168 * to blk_queue_make_request().
169 *
170 * Caveat:
171 * The driver that does this *must* be able to deal appropriately
172 * with buffers in "highmemory". This can be accomplished by either calling
173 * __bio_kmap_atomic() to get a temporary kernel mapping, or by calling
174 * blk_queue_bounce() to create a buffer in normal memory.
175 **/
Jens Axboe6728cb02008-01-31 13:03:55 +0100176void blk_queue_make_request(struct request_queue *q, make_request_fn *mfn)
Jens Axboe86db1e22008-01-29 14:53:40 +0100177{
178 /*
179 * set defaults
180 */
181 q->nr_requests = BLKDEV_MAX_RQ;
Milan Broz0e435ac2008-12-03 12:55:08 +0100182
Jens Axboe86db1e22008-01-29 14:53:40 +0100183 q->make_request_fn = mfn;
Jens Axboe86db1e22008-01-29 14:53:40 +0100184 blk_queue_dma_alignment(q, 511);
185 blk_queue_congestion_threshold(q);
186 q->nr_batching = BLK_BATCH_REQ;
187
Martin K. Petersene475bba2009-06-16 08:23:52 +0200188 blk_set_default_limits(&q->limits);
189
Jens Axboe86db1e22008-01-29 14:53:40 +0100190 /*
191 * by default assume old behaviour and bounce for any highmem page
192 */
193 blk_queue_bounce_limit(q, BLK_BOUNCE_HIGH);
194}
Jens Axboe86db1e22008-01-29 14:53:40 +0100195EXPORT_SYMBOL(blk_queue_make_request);
196
197/**
198 * blk_queue_bounce_limit - set bounce buffer limit for queue
Tejun Heocd0aca22009-04-15 22:10:25 +0900199 * @q: the request queue for the device
Santosh Shilimkar9f7e45d2013-07-29 14:17:54 +0100200 * @max_addr: the maximum address the device can handle
Jens Axboe86db1e22008-01-29 14:53:40 +0100201 *
202 * Description:
203 * Different hardware can have different requirements as to what pages
204 * it can do I/O directly to. A low level driver can call
205 * blk_queue_bounce_limit to have lower memory pages allocated as bounce
Santosh Shilimkar9f7e45d2013-07-29 14:17:54 +0100206 * buffers for doing I/O to pages residing above @max_addr.
Jens Axboe86db1e22008-01-29 14:53:40 +0100207 **/
Santosh Shilimkar9f7e45d2013-07-29 14:17:54 +0100208void blk_queue_bounce_limit(struct request_queue *q, u64 max_addr)
Jens Axboe86db1e22008-01-29 14:53:40 +0100209{
Santosh Shilimkar9f7e45d2013-07-29 14:17:54 +0100210 unsigned long b_pfn = max_addr >> PAGE_SHIFT;
Jens Axboe86db1e22008-01-29 14:53:40 +0100211 int dma = 0;
212
213 q->bounce_gfp = GFP_NOIO;
214#if BITS_PER_LONG == 64
Tejun Heocd0aca22009-04-15 22:10:25 +0900215 /*
216 * Assume anything <= 4GB can be handled by IOMMU. Actually
217 * some IOMMUs can handle everything, but I don't know of a
218 * way to test this here.
219 */
220 if (b_pfn < (min_t(u64, 0xffffffffUL, BLK_BOUNCE_HIGH) >> PAGE_SHIFT))
Jens Axboe86db1e22008-01-29 14:53:40 +0100221 dma = 1;
Malahal Naineniefb012b32010-10-01 14:45:27 +0200222 q->limits.bounce_pfn = max(max_low_pfn, b_pfn);
Jens Axboe86db1e22008-01-29 14:53:40 +0100223#else
Jens Axboe6728cb02008-01-31 13:03:55 +0100224 if (b_pfn < blk_max_low_pfn)
Jens Axboe86db1e22008-01-29 14:53:40 +0100225 dma = 1;
Malahal Nainenic49825f2010-09-24 20:25:49 +0200226 q->limits.bounce_pfn = b_pfn;
Jens Axboe260a67a2010-10-01 14:42:43 +0200227#endif
Jens Axboe86db1e22008-01-29 14:53:40 +0100228 if (dma) {
229 init_emergency_isa_pool();
230 q->bounce_gfp = GFP_NOIO | GFP_DMA;
Jens Axboe260a67a2010-10-01 14:42:43 +0200231 q->limits.bounce_pfn = b_pfn;
Jens Axboe86db1e22008-01-29 14:53:40 +0100232 }
233}
Jens Axboe86db1e22008-01-29 14:53:40 +0100234EXPORT_SYMBOL(blk_queue_bounce_limit);
235
236/**
Mike Snitzer72d4cd92010-12-17 08:34:20 +0100237 * blk_limits_max_hw_sectors - set hard and soft limit of max sectors for request
238 * @limits: the queue limits
Martin K. Petersen2800aac2010-02-26 00:20:35 -0500239 * @max_hw_sectors: max hardware sectors in the usual 512b unit
Jens Axboe86db1e22008-01-29 14:53:40 +0100240 *
241 * Description:
Martin K. Petersen2800aac2010-02-26 00:20:35 -0500242 * Enables a low level driver to set a hard upper limit,
243 * max_hw_sectors, on the size of requests. max_hw_sectors is set by
Martin K. Petersen4f258a42015-06-23 12:13:59 -0400244 * the device driver based upon the capabilities of the I/O
245 * controller.
Martin K. Petersen2800aac2010-02-26 00:20:35 -0500246 *
247 * max_sectors is a soft limit imposed by the block layer for
248 * filesystem type requests. This value can be overridden on a
249 * per-device basis in /sys/block/<device>/queue/max_sectors_kb.
250 * The soft limit can not exceed max_hw_sectors.
Jens Axboe86db1e22008-01-29 14:53:40 +0100251 **/
Mike Snitzer72d4cd92010-12-17 08:34:20 +0100252void blk_limits_max_hw_sectors(struct queue_limits *limits, unsigned int max_hw_sectors)
Jens Axboe86db1e22008-01-29 14:53:40 +0100253{
Martin K. Petersen2800aac2010-02-26 00:20:35 -0500254 if ((max_hw_sectors << 9) < PAGE_CACHE_SIZE) {
255 max_hw_sectors = 1 << (PAGE_CACHE_SHIFT - 9);
Harvey Harrison24c03d42008-05-01 04:35:17 -0700256 printk(KERN_INFO "%s: set to minimum %d\n",
Martin K. Petersen2800aac2010-02-26 00:20:35 -0500257 __func__, max_hw_sectors);
Jens Axboe86db1e22008-01-29 14:53:40 +0100258 }
259
Christoph Hellwig34b48db2014-09-06 16:08:05 -0700260 limits->max_sectors = limits->max_hw_sectors = max_hw_sectors;
Mike Snitzer72d4cd92010-12-17 08:34:20 +0100261}
262EXPORT_SYMBOL(blk_limits_max_hw_sectors);
263
264/**
265 * blk_queue_max_hw_sectors - set max sectors for a request for this queue
266 * @q: the request queue for the device
267 * @max_hw_sectors: max hardware sectors in the usual 512b unit
268 *
269 * Description:
270 * See description for blk_limits_max_hw_sectors().
271 **/
272void blk_queue_max_hw_sectors(struct request_queue *q, unsigned int max_hw_sectors)
273{
274 blk_limits_max_hw_sectors(&q->limits, max_hw_sectors);
Jens Axboe86db1e22008-01-29 14:53:40 +0100275}
Martin K. Petersen086fa5f2010-02-26 00:20:38 -0500276EXPORT_SYMBOL(blk_queue_max_hw_sectors);
Jens Axboe86db1e22008-01-29 14:53:40 +0100277
278/**
Jens Axboe762380a2014-06-05 13:38:39 -0600279 * blk_queue_chunk_sectors - set size of the chunk for this queue
280 * @q: the request queue for the device
281 * @chunk_sectors: chunk sectors in the usual 512b unit
282 *
283 * Description:
284 * If a driver doesn't want IOs to cross a given chunk size, it can set
285 * this limit and prevent merging across chunks. Note that the chunk size
Jens Axboe58a49152014-06-10 12:53:56 -0600286 * must currently be a power-of-2 in sectors. Also note that the block
287 * layer must accept a page worth of data at any offset. So if the
288 * crossing of chunks is a hard limitation in the driver, it must still be
289 * prepared to split single page bios.
Jens Axboe762380a2014-06-05 13:38:39 -0600290 **/
291void blk_queue_chunk_sectors(struct request_queue *q, unsigned int chunk_sectors)
292{
293 BUG_ON(!is_power_of_2(chunk_sectors));
294 q->limits.chunk_sectors = chunk_sectors;
295}
296EXPORT_SYMBOL(blk_queue_chunk_sectors);
297
298/**
Christoph Hellwig67efc922009-09-30 13:54:20 +0200299 * blk_queue_max_discard_sectors - set max sectors for a single discard
300 * @q: the request queue for the device
Randy Dunlapc7ebf062009-10-12 08:20:47 +0200301 * @max_discard_sectors: maximum number of sectors to discard
Christoph Hellwig67efc922009-09-30 13:54:20 +0200302 **/
303void blk_queue_max_discard_sectors(struct request_queue *q,
304 unsigned int max_discard_sectors)
305{
306 q->limits.max_discard_sectors = max_discard_sectors;
307}
308EXPORT_SYMBOL(blk_queue_max_discard_sectors);
309
310/**
Martin K. Petersen4363ac72012-09-18 12:19:27 -0400311 * blk_queue_max_write_same_sectors - set max sectors for a single write same
312 * @q: the request queue for the device
313 * @max_write_same_sectors: maximum number of sectors to write per command
314 **/
315void blk_queue_max_write_same_sectors(struct request_queue *q,
316 unsigned int max_write_same_sectors)
317{
318 q->limits.max_write_same_sectors = max_write_same_sectors;
319}
320EXPORT_SYMBOL(blk_queue_max_write_same_sectors);
321
322/**
Martin K. Petersen8a783622010-02-26 00:20:39 -0500323 * blk_queue_max_segments - set max hw segments for a request for this queue
Jens Axboe86db1e22008-01-29 14:53:40 +0100324 * @q: the request queue for the device
325 * @max_segments: max number of segments
326 *
327 * Description:
328 * Enables a low level driver to set an upper limit on the number of
Martin K. Petersen8a783622010-02-26 00:20:39 -0500329 * hw data segments in a request.
Jens Axboe86db1e22008-01-29 14:53:40 +0100330 **/
Martin K. Petersen8a783622010-02-26 00:20:39 -0500331void blk_queue_max_segments(struct request_queue *q, unsigned short max_segments)
Jens Axboe86db1e22008-01-29 14:53:40 +0100332{
333 if (!max_segments) {
334 max_segments = 1;
Harvey Harrison24c03d42008-05-01 04:35:17 -0700335 printk(KERN_INFO "%s: set to minimum %d\n",
336 __func__, max_segments);
Jens Axboe86db1e22008-01-29 14:53:40 +0100337 }
338
Martin K. Petersen8a783622010-02-26 00:20:39 -0500339 q->limits.max_segments = max_segments;
Jens Axboe86db1e22008-01-29 14:53:40 +0100340}
Martin K. Petersen8a783622010-02-26 00:20:39 -0500341EXPORT_SYMBOL(blk_queue_max_segments);
Jens Axboe86db1e22008-01-29 14:53:40 +0100342
343/**
344 * blk_queue_max_segment_size - set max segment size for blk_rq_map_sg
345 * @q: the request queue for the device
346 * @max_size: max size of segment in bytes
347 *
348 * Description:
349 * Enables a low level driver to set an upper limit on the size of a
350 * coalesced segment
351 **/
352void blk_queue_max_segment_size(struct request_queue *q, unsigned int max_size)
353{
354 if (max_size < PAGE_CACHE_SIZE) {
355 max_size = PAGE_CACHE_SIZE;
Harvey Harrison24c03d42008-05-01 04:35:17 -0700356 printk(KERN_INFO "%s: set to minimum %d\n",
357 __func__, max_size);
Jens Axboe86db1e22008-01-29 14:53:40 +0100358 }
359
Martin K. Petersen025146e2009-05-22 17:17:51 -0400360 q->limits.max_segment_size = max_size;
Jens Axboe86db1e22008-01-29 14:53:40 +0100361}
Jens Axboe86db1e22008-01-29 14:53:40 +0100362EXPORT_SYMBOL(blk_queue_max_segment_size);
363
364/**
Martin K. Petersene1defc42009-05-22 17:17:49 -0400365 * blk_queue_logical_block_size - set logical block size for the queue
Jens Axboe86db1e22008-01-29 14:53:40 +0100366 * @q: the request queue for the device
Martin K. Petersene1defc42009-05-22 17:17:49 -0400367 * @size: the logical block size, in bytes
Jens Axboe86db1e22008-01-29 14:53:40 +0100368 *
369 * Description:
Martin K. Petersene1defc42009-05-22 17:17:49 -0400370 * This should be set to the lowest possible block size that the
371 * storage device can address. The default of 512 covers most
372 * hardware.
Jens Axboe86db1e22008-01-29 14:53:40 +0100373 **/
Martin K. Petersene1defc42009-05-22 17:17:49 -0400374void blk_queue_logical_block_size(struct request_queue *q, unsigned short size)
Jens Axboe86db1e22008-01-29 14:53:40 +0100375{
Martin K. Petersen025146e2009-05-22 17:17:51 -0400376 q->limits.logical_block_size = size;
Martin K. Petersenc72758f2009-05-22 17:17:53 -0400377
378 if (q->limits.physical_block_size < size)
379 q->limits.physical_block_size = size;
380
381 if (q->limits.io_min < q->limits.physical_block_size)
382 q->limits.io_min = q->limits.physical_block_size;
Jens Axboe86db1e22008-01-29 14:53:40 +0100383}
Martin K. Petersene1defc42009-05-22 17:17:49 -0400384EXPORT_SYMBOL(blk_queue_logical_block_size);
Jens Axboe86db1e22008-01-29 14:53:40 +0100385
Martin K. Petersenc72758f2009-05-22 17:17:53 -0400386/**
387 * blk_queue_physical_block_size - set physical block size for the queue
388 * @q: the request queue for the device
389 * @size: the physical block size, in bytes
390 *
391 * Description:
392 * This should be set to the lowest possible sector size that the
393 * hardware can operate on without reverting to read-modify-write
394 * operations.
395 */
Martin K. Petersen892b6f92010-10-13 21:18:03 +0200396void blk_queue_physical_block_size(struct request_queue *q, unsigned int size)
Martin K. Petersenc72758f2009-05-22 17:17:53 -0400397{
398 q->limits.physical_block_size = size;
399
400 if (q->limits.physical_block_size < q->limits.logical_block_size)
401 q->limits.physical_block_size = q->limits.logical_block_size;
402
403 if (q->limits.io_min < q->limits.physical_block_size)
404 q->limits.io_min = q->limits.physical_block_size;
405}
406EXPORT_SYMBOL(blk_queue_physical_block_size);
407
408/**
409 * blk_queue_alignment_offset - set physical block alignment offset
410 * @q: the request queue for the device
Randy Dunlap8ebf9752009-06-11 20:00:41 -0700411 * @offset: alignment offset in bytes
Martin K. Petersenc72758f2009-05-22 17:17:53 -0400412 *
413 * Description:
414 * Some devices are naturally misaligned to compensate for things like
415 * the legacy DOS partition table 63-sector offset. Low-level drivers
416 * should call this function for devices whose first sector is not
417 * naturally aligned.
418 */
419void blk_queue_alignment_offset(struct request_queue *q, unsigned int offset)
420{
421 q->limits.alignment_offset =
422 offset & (q->limits.physical_block_size - 1);
423 q->limits.misaligned = 0;
424}
425EXPORT_SYMBOL(blk_queue_alignment_offset);
426
427/**
Martin K. Petersen7c958e32009-07-31 11:49:11 -0400428 * blk_limits_io_min - set minimum request size for a device
429 * @limits: the queue limits
430 * @min: smallest I/O size in bytes
431 *
432 * Description:
433 * Some devices have an internal block size bigger than the reported
434 * hardware sector size. This function can be used to signal the
435 * smallest I/O the device can perform without incurring a performance
436 * penalty.
437 */
438void blk_limits_io_min(struct queue_limits *limits, unsigned int min)
439{
440 limits->io_min = min;
441
442 if (limits->io_min < limits->logical_block_size)
443 limits->io_min = limits->logical_block_size;
444
445 if (limits->io_min < limits->physical_block_size)
446 limits->io_min = limits->physical_block_size;
447}
448EXPORT_SYMBOL(blk_limits_io_min);
449
450/**
Martin K. Petersenc72758f2009-05-22 17:17:53 -0400451 * blk_queue_io_min - set minimum request size for the queue
452 * @q: the request queue for the device
Randy Dunlap8ebf9752009-06-11 20:00:41 -0700453 * @min: smallest I/O size in bytes
Martin K. Petersenc72758f2009-05-22 17:17:53 -0400454 *
455 * Description:
Martin K. Petersen7e5f5fb2009-07-31 11:49:13 -0400456 * Storage devices may report a granularity or preferred minimum I/O
457 * size which is the smallest request the device can perform without
458 * incurring a performance penalty. For disk drives this is often the
459 * physical block size. For RAID arrays it is often the stripe chunk
460 * size. A properly aligned multiple of minimum_io_size is the
461 * preferred request size for workloads where a high number of I/O
462 * operations is desired.
Martin K. Petersenc72758f2009-05-22 17:17:53 -0400463 */
464void blk_queue_io_min(struct request_queue *q, unsigned int min)
465{
Martin K. Petersen7c958e32009-07-31 11:49:11 -0400466 blk_limits_io_min(&q->limits, min);
Martin K. Petersenc72758f2009-05-22 17:17:53 -0400467}
468EXPORT_SYMBOL(blk_queue_io_min);
469
470/**
Martin K. Petersen3c5820c2009-09-11 21:54:52 +0200471 * blk_limits_io_opt - set optimal request size for a device
472 * @limits: the queue limits
473 * @opt: smallest I/O size in bytes
474 *
475 * Description:
476 * Storage devices may report an optimal I/O size, which is the
477 * device's preferred unit for sustained I/O. This is rarely reported
478 * for disk drives. For RAID arrays it is usually the stripe width or
479 * the internal track size. A properly aligned multiple of
480 * optimal_io_size is the preferred request size for workloads where
481 * sustained throughput is desired.
482 */
483void blk_limits_io_opt(struct queue_limits *limits, unsigned int opt)
484{
485 limits->io_opt = opt;
486}
487EXPORT_SYMBOL(blk_limits_io_opt);
488
489/**
Martin K. Petersenc72758f2009-05-22 17:17:53 -0400490 * blk_queue_io_opt - set optimal request size for the queue
491 * @q: the request queue for the device
Randy Dunlap8ebf9752009-06-11 20:00:41 -0700492 * @opt: optimal request size in bytes
Martin K. Petersenc72758f2009-05-22 17:17:53 -0400493 *
494 * Description:
Martin K. Petersen7e5f5fb2009-07-31 11:49:13 -0400495 * Storage devices may report an optimal I/O size, which is the
496 * device's preferred unit for sustained I/O. This is rarely reported
497 * for disk drives. For RAID arrays it is usually the stripe width or
498 * the internal track size. A properly aligned multiple of
499 * optimal_io_size is the preferred request size for workloads where
500 * sustained throughput is desired.
Martin K. Petersenc72758f2009-05-22 17:17:53 -0400501 */
502void blk_queue_io_opt(struct request_queue *q, unsigned int opt)
503{
Martin K. Petersen3c5820c2009-09-11 21:54:52 +0200504 blk_limits_io_opt(&q->limits, opt);
Martin K. Petersenc72758f2009-05-22 17:17:53 -0400505}
506EXPORT_SYMBOL(blk_queue_io_opt);
507
Jens Axboe86db1e22008-01-29 14:53:40 +0100508/**
509 * blk_queue_stack_limits - inherit underlying queue limits for stacked drivers
510 * @t: the stacking driver (top)
511 * @b: the underlying device (bottom)
512 **/
513void blk_queue_stack_limits(struct request_queue *t, struct request_queue *b)
514{
Martin K. Petersenfef24662009-07-31 11:49:10 -0400515 blk_stack_limits(&t->limits, &b->limits, 0);
Jens Axboe86db1e22008-01-29 14:53:40 +0100516}
Jens Axboe86db1e22008-01-29 14:53:40 +0100517EXPORT_SYMBOL(blk_queue_stack_limits);
518
519/**
Martin K. Petersenc72758f2009-05-22 17:17:53 -0400520 * blk_stack_limits - adjust queue_limits for stacked devices
Martin K. Petersen81744ee2009-12-29 08:35:35 +0100521 * @t: the stacking driver limits (top device)
522 * @b: the underlying queue limits (bottom, component device)
Martin K. Petersene03a72e2010-01-11 03:21:51 -0500523 * @start: first data sector within component device
Martin K. Petersenc72758f2009-05-22 17:17:53 -0400524 *
525 * Description:
Martin K. Petersen81744ee2009-12-29 08:35:35 +0100526 * This function is used by stacking drivers like MD and DM to ensure
527 * that all component devices have compatible block sizes and
528 * alignments. The stacking driver must provide a queue_limits
529 * struct (top) and then iteratively call the stacking function for
530 * all component (bottom) devices. The stacking function will
531 * attempt to combine the values and ensure proper alignment.
532 *
533 * Returns 0 if the top and bottom queue_limits are compatible. The
534 * top device's block sizes and alignment offsets may be adjusted to
535 * ensure alignment with the bottom device. If no compatible sizes
536 * and alignments exist, -1 is returned and the resulting top
537 * queue_limits will have the misaligned flag set to indicate that
538 * the alignment_offset is undefined.
Martin K. Petersenc72758f2009-05-22 17:17:53 -0400539 */
540int blk_stack_limits(struct queue_limits *t, struct queue_limits *b,
Martin K. Petersene03a72e2010-01-11 03:21:51 -0500541 sector_t start)
Martin K. Petersenc72758f2009-05-22 17:17:53 -0400542{
Martin K. Petersene03a72e2010-01-11 03:21:51 -0500543 unsigned int top, bottom, alignment, ret = 0;
Martin K. Petersen86b37282009-11-10 11:50:21 +0100544
Martin K. Petersenc72758f2009-05-22 17:17:53 -0400545 t->max_sectors = min_not_zero(t->max_sectors, b->max_sectors);
546 t->max_hw_sectors = min_not_zero(t->max_hw_sectors, b->max_hw_sectors);
Martin K. Petersen4363ac72012-09-18 12:19:27 -0400547 t->max_write_same_sectors = min(t->max_write_same_sectors,
548 b->max_write_same_sectors);
Martin K. Petersen77634f32009-06-09 06:23:22 +0200549 t->bounce_pfn = min_not_zero(t->bounce_pfn, b->bounce_pfn);
Martin K. Petersenc72758f2009-05-22 17:17:53 -0400550
551 t->seg_boundary_mask = min_not_zero(t->seg_boundary_mask,
552 b->seg_boundary_mask);
553
Martin K. Petersen8a783622010-02-26 00:20:39 -0500554 t->max_segments = min_not_zero(t->max_segments, b->max_segments);
Martin K. Petersen13f05c82010-09-10 20:50:10 +0200555 t->max_integrity_segments = min_not_zero(t->max_integrity_segments,
556 b->max_integrity_segments);
Martin K. Petersenc72758f2009-05-22 17:17:53 -0400557
558 t->max_segment_size = min_not_zero(t->max_segment_size,
559 b->max_segment_size);
560
Martin K. Petersenfe0b3932010-01-11 03:21:47 -0500561 t->misaligned |= b->misaligned;
562
Martin K. Petersene03a72e2010-01-11 03:21:51 -0500563 alignment = queue_limit_alignment_offset(b, start);
Martin K. Petersen9504e082009-12-21 15:55:51 +0100564
Martin K. Petersen81744ee2009-12-29 08:35:35 +0100565 /* Bottom device has different alignment. Check that it is
566 * compatible with the current top alignment.
567 */
Martin K. Petersen9504e082009-12-21 15:55:51 +0100568 if (t->alignment_offset != alignment) {
569
570 top = max(t->physical_block_size, t->io_min)
571 + t->alignment_offset;
Martin K. Petersen81744ee2009-12-29 08:35:35 +0100572 bottom = max(b->physical_block_size, b->io_min) + alignment;
Martin K. Petersen9504e082009-12-21 15:55:51 +0100573
Martin K. Petersen81744ee2009-12-29 08:35:35 +0100574 /* Verify that top and bottom intervals line up */
Mike Snitzerb8839b82014-10-08 18:26:13 -0400575 if (max(top, bottom) % min(top, bottom)) {
Martin K. Petersen9504e082009-12-21 15:55:51 +0100576 t->misaligned = 1;
Martin K. Petersenfe0b3932010-01-11 03:21:47 -0500577 ret = -1;
578 }
Martin K. Petersen9504e082009-12-21 15:55:51 +0100579 }
580
Martin K. Petersenc72758f2009-05-22 17:17:53 -0400581 t->logical_block_size = max(t->logical_block_size,
582 b->logical_block_size);
583
584 t->physical_block_size = max(t->physical_block_size,
585 b->physical_block_size);
586
587 t->io_min = max(t->io_min, b->io_min);
Mike Snitzere9637412015-03-30 13:39:09 -0400588 t->io_opt = lcm_not_zero(t->io_opt, b->io_opt);
Martin K. Petersen9504e082009-12-21 15:55:51 +0100589
Martin K. Petersene692cb62010-12-01 19:41:49 +0100590 t->cluster &= b->cluster;
Martin K. Petersen98262f22009-12-03 09:24:48 +0100591 t->discard_zeroes_data &= b->discard_zeroes_data;
Martin K. Petersenc72758f2009-05-22 17:17:53 -0400592
Martin K. Petersen81744ee2009-12-29 08:35:35 +0100593 /* Physical block size a multiple of the logical block size? */
Martin K. Petersen9504e082009-12-21 15:55:51 +0100594 if (t->physical_block_size & (t->logical_block_size - 1)) {
595 t->physical_block_size = t->logical_block_size;
Martin K. Petersenc72758f2009-05-22 17:17:53 -0400596 t->misaligned = 1;
Martin K. Petersenfe0b3932010-01-11 03:21:47 -0500597 ret = -1;
Martin K. Petersen86b37282009-11-10 11:50:21 +0100598 }
599
Martin K. Petersen81744ee2009-12-29 08:35:35 +0100600 /* Minimum I/O a multiple of the physical block size? */
Martin K. Petersen9504e082009-12-21 15:55:51 +0100601 if (t->io_min & (t->physical_block_size - 1)) {
602 t->io_min = t->physical_block_size;
Martin K. Petersenc72758f2009-05-22 17:17:53 -0400603 t->misaligned = 1;
Martin K. Petersenfe0b3932010-01-11 03:21:47 -0500604 ret = -1;
Martin K. Petersenc72758f2009-05-22 17:17:53 -0400605 }
606
Martin K. Petersen81744ee2009-12-29 08:35:35 +0100607 /* Optimal I/O a multiple of the physical block size? */
Martin K. Petersen9504e082009-12-21 15:55:51 +0100608 if (t->io_opt & (t->physical_block_size - 1)) {
609 t->io_opt = 0;
610 t->misaligned = 1;
Martin K. Petersenfe0b3932010-01-11 03:21:47 -0500611 ret = -1;
Martin K. Petersen9504e082009-12-21 15:55:51 +0100612 }
Martin K. Petersen70dd5bf2009-07-31 11:49:12 -0400613
Kent Overstreetc78afc62013-07-11 22:39:53 -0700614 t->raid_partial_stripes_expensive =
615 max(t->raid_partial_stripes_expensive,
616 b->raid_partial_stripes_expensive);
617
Martin K. Petersen81744ee2009-12-29 08:35:35 +0100618 /* Find lowest common alignment_offset */
Mike Snitzere9637412015-03-30 13:39:09 -0400619 t->alignment_offset = lcm_not_zero(t->alignment_offset, alignment)
Mike Snitzerb8839b82014-10-08 18:26:13 -0400620 % max(t->physical_block_size, t->io_min);
Martin K. Petersen70dd5bf2009-07-31 11:49:12 -0400621
Martin K. Petersen81744ee2009-12-29 08:35:35 +0100622 /* Verify that new alignment_offset is on a logical block boundary */
Martin K. Petersenfe0b3932010-01-11 03:21:47 -0500623 if (t->alignment_offset & (t->logical_block_size - 1)) {
Martin K. Petersen9504e082009-12-21 15:55:51 +0100624 t->misaligned = 1;
Martin K. Petersenfe0b3932010-01-11 03:21:47 -0500625 ret = -1;
626 }
Martin K. Petersen9504e082009-12-21 15:55:51 +0100627
628 /* Discard alignment and granularity */
629 if (b->discard_granularity) {
Martin K. Petersene03a72e2010-01-11 03:21:51 -0500630 alignment = queue_limit_discard_alignment(b, start);
Martin K. Petersen9504e082009-12-21 15:55:51 +0100631
632 if (t->discard_granularity != 0 &&
633 t->discard_alignment != alignment) {
634 top = t->discard_granularity + t->discard_alignment;
635 bottom = b->discard_granularity + alignment;
636
637 /* Verify that top and bottom intervals line up */
Shaohua Li8dd2cb72012-12-14 11:15:36 +0800638 if ((max(top, bottom) % min(top, bottom)) != 0)
Martin K. Petersen9504e082009-12-21 15:55:51 +0100639 t->discard_misaligned = 1;
640 }
641
Martin K. Petersen81744ee2009-12-29 08:35:35 +0100642 t->max_discard_sectors = min_not_zero(t->max_discard_sectors,
643 b->max_discard_sectors);
Martin K. Petersen9504e082009-12-21 15:55:51 +0100644 t->discard_granularity = max(t->discard_granularity,
645 b->discard_granularity);
Mike Snitzere9637412015-03-30 13:39:09 -0400646 t->discard_alignment = lcm_not_zero(t->discard_alignment, alignment) %
Shaohua Li8dd2cb72012-12-14 11:15:36 +0800647 t->discard_granularity;
Martin K. Petersen9504e082009-12-21 15:55:51 +0100648 }
649
Martin K. Petersenfe0b3932010-01-11 03:21:47 -0500650 return ret;
Martin K. Petersenc72758f2009-05-22 17:17:53 -0400651}
Mike Snitzer5d85d322009-05-28 11:04:53 +0200652EXPORT_SYMBOL(blk_stack_limits);
Martin K. Petersenc72758f2009-05-22 17:17:53 -0400653
654/**
Martin K. Petersen17be8c22010-01-11 03:21:49 -0500655 * bdev_stack_limits - adjust queue limits for stacked drivers
656 * @t: the stacking driver limits (top device)
657 * @bdev: the component block_device (bottom)
658 * @start: first data sector within component device
659 *
660 * Description:
661 * Merges queue limits for a top device and a block_device. Returns
662 * 0 if alignment didn't change. Returns -1 if adding the bottom
663 * device caused misalignment.
664 */
665int bdev_stack_limits(struct queue_limits *t, struct block_device *bdev,
666 sector_t start)
667{
668 struct request_queue *bq = bdev_get_queue(bdev);
669
670 start += get_start_sect(bdev);
671
Martin K. Petersene03a72e2010-01-11 03:21:51 -0500672 return blk_stack_limits(t, &bq->limits, start);
Martin K. Petersen17be8c22010-01-11 03:21:49 -0500673}
674EXPORT_SYMBOL(bdev_stack_limits);
675
676/**
Martin K. Petersenc72758f2009-05-22 17:17:53 -0400677 * disk_stack_limits - adjust queue limits for stacked drivers
Martin K. Petersen77634f32009-06-09 06:23:22 +0200678 * @disk: MD/DM gendisk (top)
Martin K. Petersenc72758f2009-05-22 17:17:53 -0400679 * @bdev: the underlying block device (bottom)
680 * @offset: offset to beginning of data within component device
681 *
682 * Description:
Martin K. Petersene03a72e2010-01-11 03:21:51 -0500683 * Merges the limits for a top level gendisk and a bottom level
684 * block_device.
Martin K. Petersenc72758f2009-05-22 17:17:53 -0400685 */
686void disk_stack_limits(struct gendisk *disk, struct block_device *bdev,
687 sector_t offset)
688{
689 struct request_queue *t = disk->queue;
Martin K. Petersenc72758f2009-05-22 17:17:53 -0400690
Martin K. Petersene03a72e2010-01-11 03:21:51 -0500691 if (bdev_stack_limits(&t->limits, bdev, offset >> 9) < 0) {
Martin K. Petersenc72758f2009-05-22 17:17:53 -0400692 char top[BDEVNAME_SIZE], bottom[BDEVNAME_SIZE];
693
694 disk_name(disk, 0, top);
695 bdevname(bdev, bottom);
696
697 printk(KERN_NOTICE "%s: Warning: Device %s is misaligned\n",
698 top, bottom);
699 }
Martin K. Petersenc72758f2009-05-22 17:17:53 -0400700}
701EXPORT_SYMBOL(disk_stack_limits);
702
703/**
Tejun Heoe3790c72008-03-04 11:18:17 +0100704 * blk_queue_dma_pad - set pad mask
705 * @q: the request queue for the device
706 * @mask: pad mask
707 *
FUJITA Tomonori27f82212008-07-04 09:30:03 +0200708 * Set dma pad mask.
Tejun Heoe3790c72008-03-04 11:18:17 +0100709 *
FUJITA Tomonori27f82212008-07-04 09:30:03 +0200710 * Appending pad buffer to a request modifies the last entry of a
711 * scatter list such that it includes the pad buffer.
Tejun Heoe3790c72008-03-04 11:18:17 +0100712 **/
713void blk_queue_dma_pad(struct request_queue *q, unsigned int mask)
714{
715 q->dma_pad_mask = mask;
716}
717EXPORT_SYMBOL(blk_queue_dma_pad);
718
719/**
FUJITA Tomonori27f82212008-07-04 09:30:03 +0200720 * blk_queue_update_dma_pad - update pad mask
721 * @q: the request queue for the device
722 * @mask: pad mask
723 *
724 * Update dma pad mask.
725 *
726 * Appending pad buffer to a request modifies the last entry of a
727 * scatter list such that it includes the pad buffer.
728 **/
729void blk_queue_update_dma_pad(struct request_queue *q, unsigned int mask)
730{
731 if (mask > q->dma_pad_mask)
732 q->dma_pad_mask = mask;
733}
734EXPORT_SYMBOL(blk_queue_update_dma_pad);
735
736/**
Jens Axboe86db1e22008-01-29 14:53:40 +0100737 * blk_queue_dma_drain - Set up a drain buffer for excess dma.
Jens Axboe86db1e22008-01-29 14:53:40 +0100738 * @q: the request queue for the device
Tejun Heo2fb98e82008-02-19 11:36:53 +0100739 * @dma_drain_needed: fn which returns non-zero if drain is necessary
Jens Axboe86db1e22008-01-29 14:53:40 +0100740 * @buf: physically contiguous buffer
741 * @size: size of the buffer in bytes
742 *
743 * Some devices have excess DMA problems and can't simply discard (or
744 * zero fill) the unwanted piece of the transfer. They have to have a
745 * real area of memory to transfer it into. The use case for this is
746 * ATAPI devices in DMA mode. If the packet command causes a transfer
747 * bigger than the transfer size some HBAs will lock up if there
748 * aren't DMA elements to contain the excess transfer. What this API
749 * does is adjust the queue so that the buf is always appended
750 * silently to the scatterlist.
751 *
Martin K. Petersen8a783622010-02-26 00:20:39 -0500752 * Note: This routine adjusts max_hw_segments to make room for appending
753 * the drain buffer. If you call blk_queue_max_segments() after calling
754 * this routine, you must set the limit to one fewer than your device
755 * can support otherwise there won't be room for the drain buffer.
Jens Axboe86db1e22008-01-29 14:53:40 +0100756 */
Harvey Harrison448da4d2008-03-04 11:30:18 +0100757int blk_queue_dma_drain(struct request_queue *q,
Tejun Heo2fb98e82008-02-19 11:36:53 +0100758 dma_drain_needed_fn *dma_drain_needed,
759 void *buf, unsigned int size)
Jens Axboe86db1e22008-01-29 14:53:40 +0100760{
Martin K. Petersen8a783622010-02-26 00:20:39 -0500761 if (queue_max_segments(q) < 2)
Jens Axboe86db1e22008-01-29 14:53:40 +0100762 return -EINVAL;
763 /* make room for appending the drain */
Martin K. Petersen8a783622010-02-26 00:20:39 -0500764 blk_queue_max_segments(q, queue_max_segments(q) - 1);
Tejun Heo2fb98e82008-02-19 11:36:53 +0100765 q->dma_drain_needed = dma_drain_needed;
Jens Axboe86db1e22008-01-29 14:53:40 +0100766 q->dma_drain_buffer = buf;
767 q->dma_drain_size = size;
768
769 return 0;
770}
Jens Axboe86db1e22008-01-29 14:53:40 +0100771EXPORT_SYMBOL_GPL(blk_queue_dma_drain);
772
773/**
774 * blk_queue_segment_boundary - set boundary rules for segment merging
775 * @q: the request queue for the device
776 * @mask: the memory boundary mask
777 **/
778void blk_queue_segment_boundary(struct request_queue *q, unsigned long mask)
779{
780 if (mask < PAGE_CACHE_SIZE - 1) {
781 mask = PAGE_CACHE_SIZE - 1;
Harvey Harrison24c03d42008-05-01 04:35:17 -0700782 printk(KERN_INFO "%s: set to minimum %lx\n",
783 __func__, mask);
Jens Axboe86db1e22008-01-29 14:53:40 +0100784 }
785
Martin K. Petersen025146e2009-05-22 17:17:51 -0400786 q->limits.seg_boundary_mask = mask;
Jens Axboe86db1e22008-01-29 14:53:40 +0100787}
Jens Axboe86db1e22008-01-29 14:53:40 +0100788EXPORT_SYMBOL(blk_queue_segment_boundary);
789
790/**
791 * blk_queue_dma_alignment - set dma length and memory alignment
792 * @q: the request queue for the device
793 * @mask: alignment mask
794 *
795 * description:
Randy Dunlap710027a2008-08-19 20:13:11 +0200796 * set required memory and length alignment for direct dma transactions.
Alan Cox8feb4d22009-04-01 15:01:39 +0100797 * this is used when building direct io requests for the queue.
Jens Axboe86db1e22008-01-29 14:53:40 +0100798 *
799 **/
800void blk_queue_dma_alignment(struct request_queue *q, int mask)
801{
802 q->dma_alignment = mask;
803}
Jens Axboe86db1e22008-01-29 14:53:40 +0100804EXPORT_SYMBOL(blk_queue_dma_alignment);
805
806/**
807 * blk_queue_update_dma_alignment - update dma length and memory alignment
808 * @q: the request queue for the device
809 * @mask: alignment mask
810 *
811 * description:
Randy Dunlap710027a2008-08-19 20:13:11 +0200812 * update required memory and length alignment for direct dma transactions.
Jens Axboe86db1e22008-01-29 14:53:40 +0100813 * If the requested alignment is larger than the current alignment, then
814 * the current queue alignment is updated to the new value, otherwise it
815 * is left alone. The design of this is to allow multiple objects
816 * (driver, device, transport etc) to set their respective
817 * alignments without having them interfere.
818 *
819 **/
820void blk_queue_update_dma_alignment(struct request_queue *q, int mask)
821{
822 BUG_ON(mask > PAGE_SIZE);
823
824 if (mask > q->dma_alignment)
825 q->dma_alignment = mask;
826}
Jens Axboe86db1e22008-01-29 14:53:40 +0100827EXPORT_SYMBOL(blk_queue_update_dma_alignment);
828
Tejun Heo4913efe2010-09-03 11:56:16 +0200829/**
830 * blk_queue_flush - configure queue's cache flush capability
831 * @q: the request queue for the device
832 * @flush: 0, REQ_FLUSH or REQ_FLUSH | REQ_FUA
833 *
834 * Tell block layer cache flush capability of @q. If it supports
835 * flushing, REQ_FLUSH should be set. If it supports bypassing
836 * write cache for individual writes, REQ_FUA should be set.
837 */
838void blk_queue_flush(struct request_queue *q, unsigned int flush)
839{
840 WARN_ON_ONCE(flush & ~(REQ_FLUSH | REQ_FUA));
841
842 if (WARN_ON_ONCE(!(flush & REQ_FLUSH) && (flush & REQ_FUA)))
843 flush &= ~REQ_FUA;
844
845 q->flush_flags = flush & (REQ_FLUSH | REQ_FUA);
846}
847EXPORT_SYMBOL_GPL(blk_queue_flush);
848
shaohua.li@intel.comf3876932011-05-06 11:34:32 -0600849void blk_queue_flush_queueable(struct request_queue *q, bool queueable)
850{
851 q->flush_not_queueable = !queueable;
852}
853EXPORT_SYMBOL_GPL(blk_queue_flush_queueable);
854
Harvey Harrisonaeb3d3a2008-08-28 09:27:42 +0200855static int __init blk_settings_init(void)
Jens Axboe86db1e22008-01-29 14:53:40 +0100856{
857 blk_max_low_pfn = max_low_pfn - 1;
858 blk_max_pfn = max_pfn - 1;
859 return 0;
860}
861subsys_initcall(blk_settings_init);