blob: 8a3ea3bba10d6c06a7276a3146864b3c674271b3 [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 */
10
11#include "blk.h"
12
Jens Axboe6728cb02008-01-31 13:03:55 +010013unsigned long blk_max_low_pfn;
Jens Axboe86db1e22008-01-29 14:53:40 +010014EXPORT_SYMBOL(blk_max_low_pfn);
Jens Axboe6728cb02008-01-31 13:03:55 +010015
16unsigned long blk_max_pfn;
Jens Axboe86db1e22008-01-29 14:53:40 +010017
18/**
19 * blk_queue_prep_rq - set a prepare_request function for queue
20 * @q: queue
21 * @pfn: prepare_request function
22 *
23 * It's possible for a queue to register a prepare_request callback which
24 * is invoked before the request is handed to the request_fn. The goal of
25 * the function is to prepare a request for I/O, it can be used to build a
26 * cdb from the request data for instance.
27 *
28 */
29void blk_queue_prep_rq(struct request_queue *q, prep_rq_fn *pfn)
30{
31 q->prep_rq_fn = pfn;
32}
Jens Axboe86db1e22008-01-29 14:53:40 +010033EXPORT_SYMBOL(blk_queue_prep_rq);
34
35/**
David Woodhousefb2dce82008-08-05 18:01:53 +010036 * blk_queue_set_discard - set a discard_sectors function for queue
37 * @q: queue
38 * @dfn: prepare_discard function
39 *
40 * It's possible for a queue to register a discard callback which is used
41 * to transform a discard request into the appropriate type for the
42 * hardware. If none is registered, then discard requests are failed
43 * with %EOPNOTSUPP.
44 *
45 */
46void blk_queue_set_discard(struct request_queue *q, prepare_discard_fn *dfn)
47{
48 q->prepare_discard_fn = dfn;
49}
50EXPORT_SYMBOL(blk_queue_set_discard);
51
52/**
Jens Axboe86db1e22008-01-29 14:53:40 +010053 * blk_queue_merge_bvec - set a merge_bvec function for queue
54 * @q: queue
55 * @mbfn: merge_bvec_fn
56 *
57 * Usually queues have static limitations on the max sectors or segments that
58 * we can put in a request. Stacking drivers may have some settings that
59 * are dynamic, and thus we have to query the queue whether it is ok to
60 * add a new bio_vec to a bio at a given offset or not. If the block device
61 * has such limitations, it needs to register a merge_bvec_fn to control
62 * the size of bio's sent to it. Note that a block device *must* allow a
63 * single page to be added to an empty bio. The block device driver may want
64 * to use the bio_split() function to deal with these bio's. By default
65 * no merge_bvec_fn is defined for a queue, and only the fixed limits are
66 * honored.
67 */
68void blk_queue_merge_bvec(struct request_queue *q, merge_bvec_fn *mbfn)
69{
70 q->merge_bvec_fn = mbfn;
71}
Jens Axboe86db1e22008-01-29 14:53:40 +010072EXPORT_SYMBOL(blk_queue_merge_bvec);
73
74void blk_queue_softirq_done(struct request_queue *q, softirq_done_fn *fn)
75{
76 q->softirq_done_fn = fn;
77}
Jens Axboe86db1e22008-01-29 14:53:40 +010078EXPORT_SYMBOL(blk_queue_softirq_done);
79
Jens Axboe242f9dc2008-09-14 05:55:09 -070080void blk_queue_rq_timeout(struct request_queue *q, unsigned int timeout)
81{
82 q->rq_timeout = timeout;
83}
84EXPORT_SYMBOL_GPL(blk_queue_rq_timeout);
85
86void blk_queue_rq_timed_out(struct request_queue *q, rq_timed_out_fn *fn)
87{
88 q->rq_timed_out_fn = fn;
89}
90EXPORT_SYMBOL_GPL(blk_queue_rq_timed_out);
91
Kiyoshi Uedaef9e3fa2008-10-01 16:12:15 +020092void blk_queue_lld_busy(struct request_queue *q, lld_busy_fn *fn)
93{
94 q->lld_busy_fn = fn;
95}
96EXPORT_SYMBOL_GPL(blk_queue_lld_busy);
97
Jens Axboe86db1e22008-01-29 14:53:40 +010098/**
Martin K. Petersene475bba2009-06-16 08:23:52 +020099 * blk_set_default_limits - reset limits to default values
Randy Dunlapf740f5ca2009-06-19 09:18:32 +0200100 * @lim: the queue_limits structure to reset
Martin K. Petersene475bba2009-06-16 08:23:52 +0200101 *
102 * Description:
103 * Returns a queue_limit struct to its default state. Can be used by
104 * stacking drivers like DM that stage table swaps and reuse an
105 * existing device queue.
106 */
107void blk_set_default_limits(struct queue_limits *lim)
108{
109 lim->max_phys_segments = MAX_PHYS_SEGMENTS;
110 lim->max_hw_segments = MAX_HW_SEGMENTS;
111 lim->seg_boundary_mask = BLK_SEG_BOUNDARY_MASK;
112 lim->max_segment_size = MAX_SEGMENT_SIZE;
113 lim->max_sectors = lim->max_hw_sectors = SAFE_MAX_SECTORS;
114 lim->logical_block_size = lim->physical_block_size = lim->io_min = 512;
Martin K. Petersen3a02c8e2009-06-18 09:56:03 +0200115 lim->bounce_pfn = (unsigned long)(BLK_BOUNCE_ANY >> PAGE_SHIFT);
Martin K. Petersene475bba2009-06-16 08:23:52 +0200116 lim->alignment_offset = 0;
117 lim->io_opt = 0;
118 lim->misaligned = 0;
119 lim->no_cluster = 0;
120}
121EXPORT_SYMBOL(blk_set_default_limits);
122
123/**
Jens Axboe86db1e22008-01-29 14:53:40 +0100124 * blk_queue_make_request - define an alternate make_request function for a device
125 * @q: the request queue for the device to be affected
126 * @mfn: the alternate make_request function
127 *
128 * Description:
129 * The normal way for &struct bios to be passed to a device
130 * driver is for them to be collected into requests on a request
131 * queue, and then to allow the device driver to select requests
132 * off that queue when it is ready. This works well for many block
133 * devices. However some block devices (typically virtual devices
134 * such as md or lvm) do not benefit from the processing on the
135 * request queue, and are served best by having the requests passed
136 * directly to them. This can be achieved by providing a function
137 * to blk_queue_make_request().
138 *
139 * Caveat:
140 * The driver that does this *must* be able to deal appropriately
141 * with buffers in "highmemory". This can be accomplished by either calling
142 * __bio_kmap_atomic() to get a temporary kernel mapping, or by calling
143 * blk_queue_bounce() to create a buffer in normal memory.
144 **/
Jens Axboe6728cb02008-01-31 13:03:55 +0100145void blk_queue_make_request(struct request_queue *q, make_request_fn *mfn)
Jens Axboe86db1e22008-01-29 14:53:40 +0100146{
147 /*
148 * set defaults
149 */
150 q->nr_requests = BLKDEV_MAX_RQ;
Milan Broz0e435ac2008-12-03 12:55:08 +0100151
Jens Axboe86db1e22008-01-29 14:53:40 +0100152 q->make_request_fn = mfn;
Jens Axboe86db1e22008-01-29 14:53:40 +0100153 blk_queue_dma_alignment(q, 511);
154 blk_queue_congestion_threshold(q);
155 q->nr_batching = BLK_BATCH_REQ;
156
157 q->unplug_thresh = 4; /* hmm */
158 q->unplug_delay = (3 * HZ) / 1000; /* 3 milliseconds */
159 if (q->unplug_delay == 0)
160 q->unplug_delay = 1;
161
Jens Axboe86db1e22008-01-29 14:53:40 +0100162 q->unplug_timer.function = blk_unplug_timeout;
163 q->unplug_timer.data = (unsigned long)q;
164
Martin K. Petersene475bba2009-06-16 08:23:52 +0200165 blk_set_default_limits(&q->limits);
166
Jens Axboe86db1e22008-01-29 14:53:40 +0100167 /*
Jens Axboea4e7d462009-07-28 09:07:29 +0200168 * If the caller didn't supply a lock, fall back to our embedded
169 * per-queue locks
170 */
171 if (!q->queue_lock)
172 q->queue_lock = &q->__queue_lock;
173
174 /*
Jens Axboe86db1e22008-01-29 14:53:40 +0100175 * by default assume old behaviour and bounce for any highmem page
176 */
177 blk_queue_bounce_limit(q, BLK_BOUNCE_HIGH);
178}
Jens Axboe86db1e22008-01-29 14:53:40 +0100179EXPORT_SYMBOL(blk_queue_make_request);
180
181/**
182 * blk_queue_bounce_limit - set bounce buffer limit for queue
Tejun Heocd0aca22009-04-15 22:10:25 +0900183 * @q: the request queue for the device
184 * @dma_mask: the maximum address the device can handle
Jens Axboe86db1e22008-01-29 14:53:40 +0100185 *
186 * Description:
187 * Different hardware can have different requirements as to what pages
188 * it can do I/O directly to. A low level driver can call
189 * blk_queue_bounce_limit to have lower memory pages allocated as bounce
Tejun Heocd0aca22009-04-15 22:10:25 +0900190 * buffers for doing I/O to pages residing above @dma_mask.
Jens Axboe86db1e22008-01-29 14:53:40 +0100191 **/
Tejun Heocd0aca22009-04-15 22:10:25 +0900192void blk_queue_bounce_limit(struct request_queue *q, u64 dma_mask)
Jens Axboe86db1e22008-01-29 14:53:40 +0100193{
Tejun Heocd0aca22009-04-15 22:10:25 +0900194 unsigned long b_pfn = dma_mask >> PAGE_SHIFT;
Jens Axboe86db1e22008-01-29 14:53:40 +0100195 int dma = 0;
196
197 q->bounce_gfp = GFP_NOIO;
198#if BITS_PER_LONG == 64
Tejun Heocd0aca22009-04-15 22:10:25 +0900199 /*
200 * Assume anything <= 4GB can be handled by IOMMU. Actually
201 * some IOMMUs can handle everything, but I don't know of a
202 * way to test this here.
203 */
204 if (b_pfn < (min_t(u64, 0xffffffffUL, BLK_BOUNCE_HIGH) >> PAGE_SHIFT))
Jens Axboe86db1e22008-01-29 14:53:40 +0100205 dma = 1;
Martin K. Petersen025146e2009-05-22 17:17:51 -0400206 q->limits.bounce_pfn = max_low_pfn;
Jens Axboe86db1e22008-01-29 14:53:40 +0100207#else
Jens Axboe6728cb02008-01-31 13:03:55 +0100208 if (b_pfn < blk_max_low_pfn)
Jens Axboe86db1e22008-01-29 14:53:40 +0100209 dma = 1;
Martin K. Petersen025146e2009-05-22 17:17:51 -0400210 q->limits.bounce_pfn = b_pfn;
Jens Axboe86db1e22008-01-29 14:53:40 +0100211#endif
212 if (dma) {
213 init_emergency_isa_pool();
214 q->bounce_gfp = GFP_NOIO | GFP_DMA;
Martin K. Petersen025146e2009-05-22 17:17:51 -0400215 q->limits.bounce_pfn = b_pfn;
Jens Axboe86db1e22008-01-29 14:53:40 +0100216 }
217}
Jens Axboe86db1e22008-01-29 14:53:40 +0100218EXPORT_SYMBOL(blk_queue_bounce_limit);
219
220/**
221 * blk_queue_max_sectors - set max sectors for a request for this queue
222 * @q: the request queue for the device
223 * @max_sectors: max sectors in the usual 512b unit
224 *
225 * Description:
226 * Enables a low level driver to set an upper limit on the size of
227 * received requests.
228 **/
229void blk_queue_max_sectors(struct request_queue *q, unsigned int max_sectors)
230{
231 if ((max_sectors << 9) < PAGE_CACHE_SIZE) {
232 max_sectors = 1 << (PAGE_CACHE_SHIFT - 9);
Harvey Harrison24c03d42008-05-01 04:35:17 -0700233 printk(KERN_INFO "%s: set to minimum %d\n",
234 __func__, max_sectors);
Jens Axboe86db1e22008-01-29 14:53:40 +0100235 }
236
237 if (BLK_DEF_MAX_SECTORS > max_sectors)
Martin K. Petersen025146e2009-05-22 17:17:51 -0400238 q->limits.max_hw_sectors = q->limits.max_sectors = max_sectors;
Jens Axboe86db1e22008-01-29 14:53:40 +0100239 else {
Martin K. Petersen025146e2009-05-22 17:17:51 -0400240 q->limits.max_sectors = BLK_DEF_MAX_SECTORS;
241 q->limits.max_hw_sectors = max_sectors;
Jens Axboe86db1e22008-01-29 14:53:40 +0100242 }
243}
Jens Axboe86db1e22008-01-29 14:53:40 +0100244EXPORT_SYMBOL(blk_queue_max_sectors);
245
Martin K. Petersenae03bf62009-05-22 17:17:50 -0400246void blk_queue_max_hw_sectors(struct request_queue *q, unsigned int max_sectors)
247{
248 if (BLK_DEF_MAX_SECTORS > max_sectors)
Martin K. Petersen025146e2009-05-22 17:17:51 -0400249 q->limits.max_hw_sectors = BLK_DEF_MAX_SECTORS;
Martin K. Petersenae03bf62009-05-22 17:17:50 -0400250 else
Martin K. Petersen025146e2009-05-22 17:17:51 -0400251 q->limits.max_hw_sectors = max_sectors;
Martin K. Petersenae03bf62009-05-22 17:17:50 -0400252}
253EXPORT_SYMBOL(blk_queue_max_hw_sectors);
254
Jens Axboe86db1e22008-01-29 14:53:40 +0100255/**
256 * blk_queue_max_phys_segments - set max phys segments for a request for this queue
257 * @q: the request queue for the device
258 * @max_segments: max number of segments
259 *
260 * Description:
261 * Enables a low level driver to set an upper limit on the number of
262 * physical data segments in a request. This would be the largest sized
263 * scatter list the driver could handle.
264 **/
265void blk_queue_max_phys_segments(struct request_queue *q,
266 unsigned short max_segments)
267{
268 if (!max_segments) {
269 max_segments = 1;
Harvey Harrison24c03d42008-05-01 04:35:17 -0700270 printk(KERN_INFO "%s: set to minimum %d\n",
271 __func__, max_segments);
Jens Axboe86db1e22008-01-29 14:53:40 +0100272 }
273
Martin K. Petersen025146e2009-05-22 17:17:51 -0400274 q->limits.max_phys_segments = max_segments;
Jens Axboe86db1e22008-01-29 14:53:40 +0100275}
Jens Axboe86db1e22008-01-29 14:53:40 +0100276EXPORT_SYMBOL(blk_queue_max_phys_segments);
277
278/**
279 * blk_queue_max_hw_segments - set max hw segments for a request for this queue
280 * @q: the request queue for the device
281 * @max_segments: max number of segments
282 *
283 * Description:
284 * Enables a low level driver to set an upper limit on the number of
285 * hw data segments in a request. This would be the largest number of
Randy Dunlap710027a2008-08-19 20:13:11 +0200286 * address/length pairs the host adapter can actually give at once
Jens Axboe86db1e22008-01-29 14:53:40 +0100287 * to the device.
288 **/
289void blk_queue_max_hw_segments(struct request_queue *q,
290 unsigned short max_segments)
291{
292 if (!max_segments) {
293 max_segments = 1;
Harvey Harrison24c03d42008-05-01 04:35:17 -0700294 printk(KERN_INFO "%s: set to minimum %d\n",
295 __func__, max_segments);
Jens Axboe86db1e22008-01-29 14:53:40 +0100296 }
297
Martin K. Petersen025146e2009-05-22 17:17:51 -0400298 q->limits.max_hw_segments = max_segments;
Jens Axboe86db1e22008-01-29 14:53:40 +0100299}
Jens Axboe86db1e22008-01-29 14:53:40 +0100300EXPORT_SYMBOL(blk_queue_max_hw_segments);
301
302/**
303 * blk_queue_max_segment_size - set max segment size for blk_rq_map_sg
304 * @q: the request queue for the device
305 * @max_size: max size of segment in bytes
306 *
307 * Description:
308 * Enables a low level driver to set an upper limit on the size of a
309 * coalesced segment
310 **/
311void blk_queue_max_segment_size(struct request_queue *q, unsigned int max_size)
312{
313 if (max_size < PAGE_CACHE_SIZE) {
314 max_size = PAGE_CACHE_SIZE;
Harvey Harrison24c03d42008-05-01 04:35:17 -0700315 printk(KERN_INFO "%s: set to minimum %d\n",
316 __func__, max_size);
Jens Axboe86db1e22008-01-29 14:53:40 +0100317 }
318
Martin K. Petersen025146e2009-05-22 17:17:51 -0400319 q->limits.max_segment_size = max_size;
Jens Axboe86db1e22008-01-29 14:53:40 +0100320}
Jens Axboe86db1e22008-01-29 14:53:40 +0100321EXPORT_SYMBOL(blk_queue_max_segment_size);
322
323/**
Martin K. Petersene1defc42009-05-22 17:17:49 -0400324 * blk_queue_logical_block_size - set logical block size for the queue
Jens Axboe86db1e22008-01-29 14:53:40 +0100325 * @q: the request queue for the device
Martin K. Petersene1defc42009-05-22 17:17:49 -0400326 * @size: the logical block size, in bytes
Jens Axboe86db1e22008-01-29 14:53:40 +0100327 *
328 * Description:
Martin K. Petersene1defc42009-05-22 17:17:49 -0400329 * This should be set to the lowest possible block size that the
330 * storage device can address. The default of 512 covers most
331 * hardware.
Jens Axboe86db1e22008-01-29 14:53:40 +0100332 **/
Martin K. Petersene1defc42009-05-22 17:17:49 -0400333void blk_queue_logical_block_size(struct request_queue *q, unsigned short size)
Jens Axboe86db1e22008-01-29 14:53:40 +0100334{
Martin K. Petersen025146e2009-05-22 17:17:51 -0400335 q->limits.logical_block_size = size;
Martin K. Petersenc72758f2009-05-22 17:17:53 -0400336
337 if (q->limits.physical_block_size < size)
338 q->limits.physical_block_size = size;
339
340 if (q->limits.io_min < q->limits.physical_block_size)
341 q->limits.io_min = q->limits.physical_block_size;
Jens Axboe86db1e22008-01-29 14:53:40 +0100342}
Martin K. Petersene1defc42009-05-22 17:17:49 -0400343EXPORT_SYMBOL(blk_queue_logical_block_size);
Jens Axboe86db1e22008-01-29 14:53:40 +0100344
Martin K. Petersenc72758f2009-05-22 17:17:53 -0400345/**
346 * blk_queue_physical_block_size - set physical block size for the queue
347 * @q: the request queue for the device
348 * @size: the physical block size, in bytes
349 *
350 * Description:
351 * This should be set to the lowest possible sector size that the
352 * hardware can operate on without reverting to read-modify-write
353 * operations.
354 */
355void blk_queue_physical_block_size(struct request_queue *q, unsigned short size)
356{
357 q->limits.physical_block_size = size;
358
359 if (q->limits.physical_block_size < q->limits.logical_block_size)
360 q->limits.physical_block_size = q->limits.logical_block_size;
361
362 if (q->limits.io_min < q->limits.physical_block_size)
363 q->limits.io_min = q->limits.physical_block_size;
364}
365EXPORT_SYMBOL(blk_queue_physical_block_size);
366
367/**
368 * blk_queue_alignment_offset - set physical block alignment offset
369 * @q: the request queue for the device
Randy Dunlap8ebf9752009-06-11 20:00:41 -0700370 * @offset: alignment offset in bytes
Martin K. Petersenc72758f2009-05-22 17:17:53 -0400371 *
372 * Description:
373 * Some devices are naturally misaligned to compensate for things like
374 * the legacy DOS partition table 63-sector offset. Low-level drivers
375 * should call this function for devices whose first sector is not
376 * naturally aligned.
377 */
378void blk_queue_alignment_offset(struct request_queue *q, unsigned int offset)
379{
380 q->limits.alignment_offset =
381 offset & (q->limits.physical_block_size - 1);
382 q->limits.misaligned = 0;
383}
384EXPORT_SYMBOL(blk_queue_alignment_offset);
385
386/**
387 * blk_queue_io_min - set minimum request size for the queue
388 * @q: the request queue for the device
Randy Dunlap8ebf9752009-06-11 20:00:41 -0700389 * @min: smallest I/O size in bytes
Martin K. Petersenc72758f2009-05-22 17:17:53 -0400390 *
391 * Description:
392 * Some devices have an internal block size bigger than the reported
393 * hardware sector size. This function can be used to signal the
394 * smallest I/O the device can perform without incurring a performance
395 * penalty.
396 */
397void blk_queue_io_min(struct request_queue *q, unsigned int min)
398{
399 q->limits.io_min = min;
400
401 if (q->limits.io_min < q->limits.logical_block_size)
402 q->limits.io_min = q->limits.logical_block_size;
403
404 if (q->limits.io_min < q->limits.physical_block_size)
405 q->limits.io_min = q->limits.physical_block_size;
406}
407EXPORT_SYMBOL(blk_queue_io_min);
408
409/**
410 * blk_queue_io_opt - set optimal request size for the queue
411 * @q: the request queue for the device
Randy Dunlap8ebf9752009-06-11 20:00:41 -0700412 * @opt: optimal request size in bytes
Martin K. Petersenc72758f2009-05-22 17:17:53 -0400413 *
414 * Description:
415 * Drivers can call this function to set the preferred I/O request
416 * size for devices that report such a value.
417 */
418void blk_queue_io_opt(struct request_queue *q, unsigned int opt)
419{
420 q->limits.io_opt = opt;
421}
422EXPORT_SYMBOL(blk_queue_io_opt);
423
Jens Axboe86db1e22008-01-29 14:53:40 +0100424/*
425 * Returns the minimum that is _not_ zero, unless both are zero.
426 */
427#define min_not_zero(l, r) (l == 0) ? r : ((r == 0) ? l : min(l, r))
428
429/**
430 * blk_queue_stack_limits - inherit underlying queue limits for stacked drivers
431 * @t: the stacking driver (top)
432 * @b: the underlying device (bottom)
433 **/
434void blk_queue_stack_limits(struct request_queue *t, struct request_queue *b)
435{
436 /* zero is "infinity" */
Martin K. Petersen025146e2009-05-22 17:17:51 -0400437 t->limits.max_sectors = min_not_zero(queue_max_sectors(t),
438 queue_max_sectors(b));
Jens Axboe86db1e22008-01-29 14:53:40 +0100439
Martin K. Petersen025146e2009-05-22 17:17:51 -0400440 t->limits.max_hw_sectors = min_not_zero(queue_max_hw_sectors(t),
441 queue_max_hw_sectors(b));
442
443 t->limits.seg_boundary_mask = min_not_zero(queue_segment_boundary(t),
444 queue_segment_boundary(b));
445
446 t->limits.max_phys_segments = min_not_zero(queue_max_phys_segments(t),
447 queue_max_phys_segments(b));
448
449 t->limits.max_hw_segments = min_not_zero(queue_max_hw_segments(t),
450 queue_max_hw_segments(b));
451
452 t->limits.max_segment_size = min_not_zero(queue_max_segment_size(t),
453 queue_max_segment_size(b));
454
455 t->limits.logical_block_size = max(queue_logical_block_size(t),
456 queue_logical_block_size(b));
457
Neil Browne7e72bf2008-05-14 16:05:54 -0700458 if (!t->queue_lock)
459 WARN_ON_ONCE(1);
460 else if (!test_bit(QUEUE_FLAG_CLUSTER, &b->queue_flags)) {
461 unsigned long flags;
462 spin_lock_irqsave(t->queue_lock, flags);
Nick Piggin75ad23b2008-04-29 14:48:33 +0200463 queue_flag_clear(QUEUE_FLAG_CLUSTER, t);
Neil Browne7e72bf2008-05-14 16:05:54 -0700464 spin_unlock_irqrestore(t->queue_lock, flags);
465 }
Jens Axboe86db1e22008-01-29 14:53:40 +0100466}
Jens Axboe86db1e22008-01-29 14:53:40 +0100467EXPORT_SYMBOL(blk_queue_stack_limits);
468
469/**
Martin K. Petersenc72758f2009-05-22 17:17:53 -0400470 * blk_stack_limits - adjust queue_limits for stacked devices
471 * @t: the stacking driver limits (top)
Martin K. Petersen77634f32009-06-09 06:23:22 +0200472 * @b: the underlying queue limits (bottom)
Martin K. Petersenc72758f2009-05-22 17:17:53 -0400473 * @offset: offset to beginning of data within component device
474 *
475 * Description:
476 * Merges two queue_limit structs. Returns 0 if alignment didn't
477 * change. Returns -1 if adding the bottom device caused
478 * misalignment.
479 */
480int blk_stack_limits(struct queue_limits *t, struct queue_limits *b,
481 sector_t offset)
482{
483 t->max_sectors = min_not_zero(t->max_sectors, b->max_sectors);
484 t->max_hw_sectors = min_not_zero(t->max_hw_sectors, b->max_hw_sectors);
Martin K. Petersen77634f32009-06-09 06:23:22 +0200485 t->bounce_pfn = min_not_zero(t->bounce_pfn, b->bounce_pfn);
Martin K. Petersenc72758f2009-05-22 17:17:53 -0400486
487 t->seg_boundary_mask = min_not_zero(t->seg_boundary_mask,
488 b->seg_boundary_mask);
489
490 t->max_phys_segments = min_not_zero(t->max_phys_segments,
491 b->max_phys_segments);
492
493 t->max_hw_segments = min_not_zero(t->max_hw_segments,
494 b->max_hw_segments);
495
496 t->max_segment_size = min_not_zero(t->max_segment_size,
497 b->max_segment_size);
498
499 t->logical_block_size = max(t->logical_block_size,
500 b->logical_block_size);
501
502 t->physical_block_size = max(t->physical_block_size,
503 b->physical_block_size);
504
505 t->io_min = max(t->io_min, b->io_min);
506 t->no_cluster |= b->no_cluster;
507
508 /* Bottom device offset aligned? */
509 if (offset &&
510 (offset & (b->physical_block_size - 1)) != b->alignment_offset) {
511 t->misaligned = 1;
512 return -1;
513 }
514
515 /* If top has no alignment offset, inherit from bottom */
516 if (!t->alignment_offset)
517 t->alignment_offset =
518 b->alignment_offset & (b->physical_block_size - 1);
519
520 /* Top device aligned on logical block boundary? */
521 if (t->alignment_offset & (t->logical_block_size - 1)) {
522 t->misaligned = 1;
523 return -1;
524 }
525
526 return 0;
527}
Mike Snitzer5d85d322009-05-28 11:04:53 +0200528EXPORT_SYMBOL(blk_stack_limits);
Martin K. Petersenc72758f2009-05-22 17:17:53 -0400529
530/**
531 * disk_stack_limits - adjust queue limits for stacked drivers
Martin K. Petersen77634f32009-06-09 06:23:22 +0200532 * @disk: MD/DM gendisk (top)
Martin K. Petersenc72758f2009-05-22 17:17:53 -0400533 * @bdev: the underlying block device (bottom)
534 * @offset: offset to beginning of data within component device
535 *
536 * Description:
537 * Merges the limits for two queues. Returns 0 if alignment
538 * didn't change. Returns -1 if adding the bottom device caused
539 * misalignment.
540 */
541void disk_stack_limits(struct gendisk *disk, struct block_device *bdev,
542 sector_t offset)
543{
544 struct request_queue *t = disk->queue;
545 struct request_queue *b = bdev_get_queue(bdev);
546
547 offset += get_start_sect(bdev) << 9;
548
549 if (blk_stack_limits(&t->limits, &b->limits, offset) < 0) {
550 char top[BDEVNAME_SIZE], bottom[BDEVNAME_SIZE];
551
552 disk_name(disk, 0, top);
553 bdevname(bdev, bottom);
554
555 printk(KERN_NOTICE "%s: Warning: Device %s is misaligned\n",
556 top, bottom);
557 }
558
559 if (!t->queue_lock)
560 WARN_ON_ONCE(1);
561 else if (!test_bit(QUEUE_FLAG_CLUSTER, &b->queue_flags)) {
562 unsigned long flags;
563
564 spin_lock_irqsave(t->queue_lock, flags);
565 if (!test_bit(QUEUE_FLAG_CLUSTER, &b->queue_flags))
566 queue_flag_clear(QUEUE_FLAG_CLUSTER, t);
567 spin_unlock_irqrestore(t->queue_lock, flags);
568 }
569}
570EXPORT_SYMBOL(disk_stack_limits);
571
572/**
Tejun Heoe3790c72008-03-04 11:18:17 +0100573 * blk_queue_dma_pad - set pad mask
574 * @q: the request queue for the device
575 * @mask: pad mask
576 *
FUJITA Tomonori27f82212008-07-04 09:30:03 +0200577 * Set dma pad mask.
Tejun Heoe3790c72008-03-04 11:18:17 +0100578 *
FUJITA Tomonori27f82212008-07-04 09:30:03 +0200579 * Appending pad buffer to a request modifies the last entry of a
580 * scatter list such that it includes the pad buffer.
Tejun Heoe3790c72008-03-04 11:18:17 +0100581 **/
582void blk_queue_dma_pad(struct request_queue *q, unsigned int mask)
583{
584 q->dma_pad_mask = mask;
585}
586EXPORT_SYMBOL(blk_queue_dma_pad);
587
588/**
FUJITA Tomonori27f82212008-07-04 09:30:03 +0200589 * blk_queue_update_dma_pad - update pad mask
590 * @q: the request queue for the device
591 * @mask: pad mask
592 *
593 * Update dma pad mask.
594 *
595 * Appending pad buffer to a request modifies the last entry of a
596 * scatter list such that it includes the pad buffer.
597 **/
598void blk_queue_update_dma_pad(struct request_queue *q, unsigned int mask)
599{
600 if (mask > q->dma_pad_mask)
601 q->dma_pad_mask = mask;
602}
603EXPORT_SYMBOL(blk_queue_update_dma_pad);
604
605/**
Jens Axboe86db1e22008-01-29 14:53:40 +0100606 * blk_queue_dma_drain - Set up a drain buffer for excess dma.
Jens Axboe86db1e22008-01-29 14:53:40 +0100607 * @q: the request queue for the device
Tejun Heo2fb98e82008-02-19 11:36:53 +0100608 * @dma_drain_needed: fn which returns non-zero if drain is necessary
Jens Axboe86db1e22008-01-29 14:53:40 +0100609 * @buf: physically contiguous buffer
610 * @size: size of the buffer in bytes
611 *
612 * Some devices have excess DMA problems and can't simply discard (or
613 * zero fill) the unwanted piece of the transfer. They have to have a
614 * real area of memory to transfer it into. The use case for this is
615 * ATAPI devices in DMA mode. If the packet command causes a transfer
616 * bigger than the transfer size some HBAs will lock up if there
617 * aren't DMA elements to contain the excess transfer. What this API
618 * does is adjust the queue so that the buf is always appended
619 * silently to the scatterlist.
620 *
621 * Note: This routine adjusts max_hw_segments to make room for
622 * appending the drain buffer. If you call
623 * blk_queue_max_hw_segments() or blk_queue_max_phys_segments() after
624 * calling this routine, you must set the limit to one fewer than your
625 * device can support otherwise there won't be room for the drain
626 * buffer.
627 */
Harvey Harrison448da4d2008-03-04 11:30:18 +0100628int blk_queue_dma_drain(struct request_queue *q,
Tejun Heo2fb98e82008-02-19 11:36:53 +0100629 dma_drain_needed_fn *dma_drain_needed,
630 void *buf, unsigned int size)
Jens Axboe86db1e22008-01-29 14:53:40 +0100631{
Martin K. Petersenae03bf62009-05-22 17:17:50 -0400632 if (queue_max_hw_segments(q) < 2 || queue_max_phys_segments(q) < 2)
Jens Axboe86db1e22008-01-29 14:53:40 +0100633 return -EINVAL;
634 /* make room for appending the drain */
Martin K. Petersenae03bf62009-05-22 17:17:50 -0400635 blk_queue_max_hw_segments(q, queue_max_hw_segments(q) - 1);
636 blk_queue_max_phys_segments(q, queue_max_phys_segments(q) - 1);
Tejun Heo2fb98e82008-02-19 11:36:53 +0100637 q->dma_drain_needed = dma_drain_needed;
Jens Axboe86db1e22008-01-29 14:53:40 +0100638 q->dma_drain_buffer = buf;
639 q->dma_drain_size = size;
640
641 return 0;
642}
Jens Axboe86db1e22008-01-29 14:53:40 +0100643EXPORT_SYMBOL_GPL(blk_queue_dma_drain);
644
645/**
646 * blk_queue_segment_boundary - set boundary rules for segment merging
647 * @q: the request queue for the device
648 * @mask: the memory boundary mask
649 **/
650void blk_queue_segment_boundary(struct request_queue *q, unsigned long mask)
651{
652 if (mask < PAGE_CACHE_SIZE - 1) {
653 mask = PAGE_CACHE_SIZE - 1;
Harvey Harrison24c03d42008-05-01 04:35:17 -0700654 printk(KERN_INFO "%s: set to minimum %lx\n",
655 __func__, mask);
Jens Axboe86db1e22008-01-29 14:53:40 +0100656 }
657
Martin K. Petersen025146e2009-05-22 17:17:51 -0400658 q->limits.seg_boundary_mask = mask;
Jens Axboe86db1e22008-01-29 14:53:40 +0100659}
Jens Axboe86db1e22008-01-29 14:53:40 +0100660EXPORT_SYMBOL(blk_queue_segment_boundary);
661
662/**
663 * blk_queue_dma_alignment - set dma length and memory alignment
664 * @q: the request queue for the device
665 * @mask: alignment mask
666 *
667 * description:
Randy Dunlap710027a2008-08-19 20:13:11 +0200668 * set required memory and length alignment for direct dma transactions.
Alan Cox8feb4d22009-04-01 15:01:39 +0100669 * this is used when building direct io requests for the queue.
Jens Axboe86db1e22008-01-29 14:53:40 +0100670 *
671 **/
672void blk_queue_dma_alignment(struct request_queue *q, int mask)
673{
674 q->dma_alignment = mask;
675}
Jens Axboe86db1e22008-01-29 14:53:40 +0100676EXPORT_SYMBOL(blk_queue_dma_alignment);
677
678/**
679 * blk_queue_update_dma_alignment - update dma length and memory alignment
680 * @q: the request queue for the device
681 * @mask: alignment mask
682 *
683 * description:
Randy Dunlap710027a2008-08-19 20:13:11 +0200684 * update required memory and length alignment for direct dma transactions.
Jens Axboe86db1e22008-01-29 14:53:40 +0100685 * If the requested alignment is larger than the current alignment, then
686 * the current queue alignment is updated to the new value, otherwise it
687 * is left alone. The design of this is to allow multiple objects
688 * (driver, device, transport etc) to set their respective
689 * alignments without having them interfere.
690 *
691 **/
692void blk_queue_update_dma_alignment(struct request_queue *q, int mask)
693{
694 BUG_ON(mask > PAGE_SIZE);
695
696 if (mask > q->dma_alignment)
697 q->dma_alignment = mask;
698}
Jens Axboe86db1e22008-01-29 14:53:40 +0100699EXPORT_SYMBOL(blk_queue_update_dma_alignment);
700
Harvey Harrisonaeb3d3a2008-08-28 09:27:42 +0200701static int __init blk_settings_init(void)
Jens Axboe86db1e22008-01-29 14:53:40 +0100702{
703 blk_max_low_pfn = max_low_pfn - 1;
704 blk_max_pfn = max_pfn - 1;
705 return 0;
706}
707subsys_initcall(blk_settings_init);