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1 | /* |
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 | #include <linux/gcd.h> |
11 | |
12 | #include "blk.h" |
13 | |
14 | unsigned long blk_max_low_pfn; |
15 | EXPORT_SYMBOL(blk_max_low_pfn); |
16 | |
17 | unsigned long blk_max_pfn; |
18 | |
19 | /** |
20 | * blk_queue_prep_rq - set a prepare_request function for queue |
21 | * @q: queue |
22 | * @pfn: prepare_request function |
23 | * |
24 | * It's possible for a queue to register a prepare_request callback which |
25 | * is invoked before the request is handed to the request_fn. The goal of |
26 | * the function is to prepare a request for I/O, it can be used to build a |
27 | * cdb from the request data for instance. |
28 | * |
29 | */ |
30 | void blk_queue_prep_rq(struct request_queue *q, prep_rq_fn *pfn) |
31 | { |
32 | q->prep_rq_fn = pfn; |
33 | } |
34 | EXPORT_SYMBOL(blk_queue_prep_rq); |
35 | |
36 | /** |
37 | * blk_queue_set_discard - set a discard_sectors function for queue |
38 | * @q: queue |
39 | * @dfn: prepare_discard function |
40 | * |
41 | * It's possible for a queue to register a discard callback which is used |
42 | * to transform a discard request into the appropriate type for the |
43 | * hardware. If none is registered, then discard requests are failed |
44 | * with %EOPNOTSUPP. |
45 | * |
46 | */ |
47 | void blk_queue_set_discard(struct request_queue *q, prepare_discard_fn *dfn) |
48 | { |
49 | q->prepare_discard_fn = dfn; |
50 | } |
51 | EXPORT_SYMBOL(blk_queue_set_discard); |
52 | |
53 | /** |
54 | * blk_queue_merge_bvec - set a merge_bvec function for queue |
55 | * @q: queue |
56 | * @mbfn: merge_bvec_fn |
57 | * |
58 | * Usually queues have static limitations on the max sectors or segments that |
59 | * we can put in a request. Stacking drivers may have some settings that |
60 | * are dynamic, and thus we have to query the queue whether it is ok to |
61 | * add a new bio_vec to a bio at a given offset or not. If the block device |
62 | * has such limitations, it needs to register a merge_bvec_fn to control |
63 | * the size of bio's sent to it. Note that a block device *must* allow a |
64 | * single page to be added to an empty bio. The block device driver may want |
65 | * to use the bio_split() function to deal with these bio's. By default |
66 | * no merge_bvec_fn is defined for a queue, and only the fixed limits are |
67 | * honored. |
68 | */ |
69 | void blk_queue_merge_bvec(struct request_queue *q, merge_bvec_fn *mbfn) |
70 | { |
71 | q->merge_bvec_fn = mbfn; |
72 | } |
73 | EXPORT_SYMBOL(blk_queue_merge_bvec); |
74 | |
75 | void blk_queue_softirq_done(struct request_queue *q, softirq_done_fn *fn) |
76 | { |
77 | q->softirq_done_fn = fn; |
78 | } |
79 | EXPORT_SYMBOL(blk_queue_softirq_done); |
80 | |
81 | void blk_queue_rq_timeout(struct request_queue *q, unsigned int timeout) |
82 | { |
83 | q->rq_timeout = timeout; |
84 | } |
85 | EXPORT_SYMBOL_GPL(blk_queue_rq_timeout); |
86 | |
87 | void blk_queue_rq_timed_out(struct request_queue *q, rq_timed_out_fn *fn) |
88 | { |
89 | q->rq_timed_out_fn = fn; |
90 | } |
91 | EXPORT_SYMBOL_GPL(blk_queue_rq_timed_out); |
92 | |
93 | void blk_queue_lld_busy(struct request_queue *q, lld_busy_fn *fn) |
94 | { |
95 | q->lld_busy_fn = fn; |
96 | } |
97 | EXPORT_SYMBOL_GPL(blk_queue_lld_busy); |
98 | |
99 | /** |
100 | * blk_set_default_limits - reset limits to default values |
101 | * @lim: the queue_limits structure to reset |
102 | * |
103 | * Description: |
104 | * Returns a queue_limit struct to its default state. Can be used by |
105 | * stacking drivers like DM that stage table swaps and reuse an |
106 | * existing device queue. |
107 | */ |
108 | void blk_set_default_limits(struct queue_limits *lim) |
109 | { |
110 | lim->max_phys_segments = MAX_PHYS_SEGMENTS; |
111 | lim->max_hw_segments = MAX_HW_SEGMENTS; |
112 | lim->seg_boundary_mask = BLK_SEG_BOUNDARY_MASK; |
113 | lim->max_segment_size = MAX_SEGMENT_SIZE; |
114 | lim->max_sectors = lim->max_hw_sectors = SAFE_MAX_SECTORS; |
115 | lim->logical_block_size = lim->physical_block_size = lim->io_min = 512; |
116 | lim->bounce_pfn = (unsigned long)(BLK_BOUNCE_ANY >> PAGE_SHIFT); |
117 | lim->alignment_offset = 0; |
118 | lim->io_opt = 0; |
119 | lim->misaligned = 0; |
120 | lim->no_cluster = 0; |
121 | } |
122 | EXPORT_SYMBOL(blk_set_default_limits); |
123 | |
124 | /** |
125 | * blk_queue_make_request - define an alternate make_request function for a device |
126 | * @q: the request queue for the device to be affected |
127 | * @mfn: the alternate make_request function |
128 | * |
129 | * Description: |
130 | * The normal way for &struct bios to be passed to a device |
131 | * driver is for them to be collected into requests on a request |
132 | * queue, and then to allow the device driver to select requests |
133 | * off that queue when it is ready. This works well for many block |
134 | * devices. However some block devices (typically virtual devices |
135 | * such as md or lvm) do not benefit from the processing on the |
136 | * request queue, and are served best by having the requests passed |
137 | * directly to them. This can be achieved by providing a function |
138 | * to blk_queue_make_request(). |
139 | * |
140 | * Caveat: |
141 | * The driver that does this *must* be able to deal appropriately |
142 | * with buffers in "highmemory". This can be accomplished by either calling |
143 | * __bio_kmap_atomic() to get a temporary kernel mapping, or by calling |
144 | * blk_queue_bounce() to create a buffer in normal memory. |
145 | **/ |
146 | void blk_queue_make_request(struct request_queue *q, make_request_fn *mfn) |
147 | { |
148 | /* |
149 | * set defaults |
150 | */ |
151 | q->nr_requests = BLKDEV_MAX_RQ; |
152 | |
153 | q->make_request_fn = mfn; |
154 | blk_queue_dma_alignment(q, 511); |
155 | blk_queue_congestion_threshold(q); |
156 | q->nr_batching = BLK_BATCH_REQ; |
157 | |
158 | q->unplug_thresh = 4; /* hmm */ |
159 | q->unplug_delay = (3 * HZ) / 1000; /* 3 milliseconds */ |
160 | if (q->unplug_delay == 0) |
161 | q->unplug_delay = 1; |
162 | |
163 | q->unplug_timer.function = blk_unplug_timeout; |
164 | q->unplug_timer.data = (unsigned long)q; |
165 | |
166 | blk_set_default_limits(&q->limits); |
167 | |
168 | /* |
169 | * If the caller didn't supply a lock, fall back to our embedded |
170 | * per-queue locks |
171 | */ |
172 | if (!q->queue_lock) |
173 | q->queue_lock = &q->__queue_lock; |
174 | |
175 | /* |
176 | * by default assume old behaviour and bounce for any highmem page |
177 | */ |
178 | blk_queue_bounce_limit(q, BLK_BOUNCE_HIGH); |
179 | } |
180 | EXPORT_SYMBOL(blk_queue_make_request); |
181 | |
182 | /** |
183 | * blk_queue_bounce_limit - set bounce buffer limit for queue |
184 | * @q: the request queue for the device |
185 | * @dma_mask: the maximum address the device can handle |
186 | * |
187 | * Description: |
188 | * Different hardware can have different requirements as to what pages |
189 | * it can do I/O directly to. A low level driver can call |
190 | * blk_queue_bounce_limit to have lower memory pages allocated as bounce |
191 | * buffers for doing I/O to pages residing above @dma_mask. |
192 | **/ |
193 | void blk_queue_bounce_limit(struct request_queue *q, u64 dma_mask) |
194 | { |
195 | unsigned long b_pfn = dma_mask >> PAGE_SHIFT; |
196 | int dma = 0; |
197 | |
198 | q->bounce_gfp = GFP_NOIO; |
199 | #if BITS_PER_LONG == 64 |
200 | /* |
201 | * Assume anything <= 4GB can be handled by IOMMU. Actually |
202 | * some IOMMUs can handle everything, but I don't know of a |
203 | * way to test this here. |
204 | */ |
205 | if (b_pfn < (min_t(u64, 0xffffffffUL, BLK_BOUNCE_HIGH) >> PAGE_SHIFT)) |
206 | dma = 1; |
207 | q->limits.bounce_pfn = max_low_pfn; |
208 | #else |
209 | if (b_pfn < blk_max_low_pfn) |
210 | dma = 1; |
211 | q->limits.bounce_pfn = b_pfn; |
212 | #endif |
213 | if (dma) { |
214 | init_emergency_isa_pool(); |
215 | q->bounce_gfp = GFP_NOIO | GFP_DMA; |
216 | q->limits.bounce_pfn = b_pfn; |
217 | } |
218 | } |
219 | EXPORT_SYMBOL(blk_queue_bounce_limit); |
220 | |
221 | /** |
222 | * blk_queue_max_sectors - set max sectors for a request for this queue |
223 | * @q: the request queue for the device |
224 | * @max_sectors: max sectors in the usual 512b unit |
225 | * |
226 | * Description: |
227 | * Enables a low level driver to set an upper limit on the size of |
228 | * received requests. |
229 | **/ |
230 | void blk_queue_max_sectors(struct request_queue *q, unsigned int max_sectors) |
231 | { |
232 | if ((max_sectors << 9) < PAGE_CACHE_SIZE) { |
233 | max_sectors = 1 << (PAGE_CACHE_SHIFT - 9); |
234 | printk(KERN_INFO "%s: set to minimum %d\n", |
235 | __func__, max_sectors); |
236 | } |
237 | |
238 | if (BLK_DEF_MAX_SECTORS > max_sectors) |
239 | q->limits.max_hw_sectors = q->limits.max_sectors = max_sectors; |
240 | else { |
241 | q->limits.max_sectors = BLK_DEF_MAX_SECTORS; |
242 | q->limits.max_hw_sectors = max_sectors; |
243 | } |
244 | } |
245 | EXPORT_SYMBOL(blk_queue_max_sectors); |
246 | |
247 | void blk_queue_max_hw_sectors(struct request_queue *q, unsigned int max_sectors) |
248 | { |
249 | if (BLK_DEF_MAX_SECTORS > max_sectors) |
250 | q->limits.max_hw_sectors = BLK_DEF_MAX_SECTORS; |
251 | else |
252 | q->limits.max_hw_sectors = max_sectors; |
253 | } |
254 | EXPORT_SYMBOL(blk_queue_max_hw_sectors); |
255 | |
256 | /** |
257 | * blk_queue_max_phys_segments - set max phys segments for a request for this queue |
258 | * @q: the request queue for the device |
259 | * @max_segments: max number of segments |
260 | * |
261 | * Description: |
262 | * Enables a low level driver to set an upper limit on the number of |
263 | * physical data segments in a request. This would be the largest sized |
264 | * scatter list the driver could handle. |
265 | **/ |
266 | void blk_queue_max_phys_segments(struct request_queue *q, |
267 | unsigned short max_segments) |
268 | { |
269 | if (!max_segments) { |
270 | max_segments = 1; |
271 | printk(KERN_INFO "%s: set to minimum %d\n", |
272 | __func__, max_segments); |
273 | } |
274 | |
275 | q->limits.max_phys_segments = max_segments; |
276 | } |
277 | EXPORT_SYMBOL(blk_queue_max_phys_segments); |
278 | |
279 | /** |
280 | * blk_queue_max_hw_segments - set max hw segments for a request for this queue |
281 | * @q: the request queue for the device |
282 | * @max_segments: max number of segments |
283 | * |
284 | * Description: |
285 | * Enables a low level driver to set an upper limit on the number of |
286 | * hw data segments in a request. This would be the largest number of |
287 | * address/length pairs the host adapter can actually give at once |
288 | * to the device. |
289 | **/ |
290 | void blk_queue_max_hw_segments(struct request_queue *q, |
291 | unsigned short max_segments) |
292 | { |
293 | if (!max_segments) { |
294 | max_segments = 1; |
295 | printk(KERN_INFO "%s: set to minimum %d\n", |
296 | __func__, max_segments); |
297 | } |
298 | |
299 | q->limits.max_hw_segments = max_segments; |
300 | } |
301 | EXPORT_SYMBOL(blk_queue_max_hw_segments); |
302 | |
303 | /** |
304 | * blk_queue_max_segment_size - set max segment size for blk_rq_map_sg |
305 | * @q: the request queue for the device |
306 | * @max_size: max size of segment in bytes |
307 | * |
308 | * Description: |
309 | * Enables a low level driver to set an upper limit on the size of a |
310 | * coalesced segment |
311 | **/ |
312 | void blk_queue_max_segment_size(struct request_queue *q, unsigned int max_size) |
313 | { |
314 | if (max_size < PAGE_CACHE_SIZE) { |
315 | max_size = PAGE_CACHE_SIZE; |
316 | printk(KERN_INFO "%s: set to minimum %d\n", |
317 | __func__, max_size); |
318 | } |
319 | |
320 | q->limits.max_segment_size = max_size; |
321 | } |
322 | EXPORT_SYMBOL(blk_queue_max_segment_size); |
323 | |
324 | /** |
325 | * blk_queue_logical_block_size - set logical block size for the queue |
326 | * @q: the request queue for the device |
327 | * @size: the logical block size, in bytes |
328 | * |
329 | * Description: |
330 | * This should be set to the lowest possible block size that the |
331 | * storage device can address. The default of 512 covers most |
332 | * hardware. |
333 | **/ |
334 | void blk_queue_logical_block_size(struct request_queue *q, unsigned short size) |
335 | { |
336 | q->limits.logical_block_size = size; |
337 | |
338 | if (q->limits.physical_block_size < size) |
339 | q->limits.physical_block_size = size; |
340 | |
341 | if (q->limits.io_min < q->limits.physical_block_size) |
342 | q->limits.io_min = q->limits.physical_block_size; |
343 | } |
344 | EXPORT_SYMBOL(blk_queue_logical_block_size); |
345 | |
346 | /** |
347 | * blk_queue_physical_block_size - set physical block size for the queue |
348 | * @q: the request queue for the device |
349 | * @size: the physical block size, in bytes |
350 | * |
351 | * Description: |
352 | * This should be set to the lowest possible sector size that the |
353 | * hardware can operate on without reverting to read-modify-write |
354 | * operations. |
355 | */ |
356 | void blk_queue_physical_block_size(struct request_queue *q, unsigned short size) |
357 | { |
358 | q->limits.physical_block_size = size; |
359 | |
360 | if (q->limits.physical_block_size < q->limits.logical_block_size) |
361 | q->limits.physical_block_size = q->limits.logical_block_size; |
362 | |
363 | if (q->limits.io_min < q->limits.physical_block_size) |
364 | q->limits.io_min = q->limits.physical_block_size; |
365 | } |
366 | EXPORT_SYMBOL(blk_queue_physical_block_size); |
367 | |
368 | /** |
369 | * blk_queue_alignment_offset - set physical block alignment offset |
370 | * @q: the request queue for the device |
371 | * @offset: alignment offset in bytes |
372 | * |
373 | * Description: |
374 | * Some devices are naturally misaligned to compensate for things like |
375 | * the legacy DOS partition table 63-sector offset. Low-level drivers |
376 | * should call this function for devices whose first sector is not |
377 | * naturally aligned. |
378 | */ |
379 | void blk_queue_alignment_offset(struct request_queue *q, unsigned int offset) |
380 | { |
381 | q->limits.alignment_offset = |
382 | offset & (q->limits.physical_block_size - 1); |
383 | q->limits.misaligned = 0; |
384 | } |
385 | EXPORT_SYMBOL(blk_queue_alignment_offset); |
386 | |
387 | /** |
388 | * blk_limits_io_min - set minimum request size for a device |
389 | * @limits: the queue limits |
390 | * @min: smallest I/O size in bytes |
391 | * |
392 | * Description: |
393 | * Some devices have an internal block size bigger than the reported |
394 | * hardware sector size. This function can be used to signal the |
395 | * smallest I/O the device can perform without incurring a performance |
396 | * penalty. |
397 | */ |
398 | void blk_limits_io_min(struct queue_limits *limits, unsigned int min) |
399 | { |
400 | limits->io_min = min; |
401 | |
402 | if (limits->io_min < limits->logical_block_size) |
403 | limits->io_min = limits->logical_block_size; |
404 | |
405 | if (limits->io_min < limits->physical_block_size) |
406 | limits->io_min = limits->physical_block_size; |
407 | } |
408 | EXPORT_SYMBOL(blk_limits_io_min); |
409 | |
410 | /** |
411 | * blk_queue_io_min - set minimum request size for the queue |
412 | * @q: the request queue for the device |
413 | * @min: smallest I/O size in bytes |
414 | * |
415 | * Description: |
416 | * Storage devices may report a granularity or preferred minimum I/O |
417 | * size which is the smallest request the device can perform without |
418 | * incurring a performance penalty. For disk drives this is often the |
419 | * physical block size. For RAID arrays it is often the stripe chunk |
420 | * size. A properly aligned multiple of minimum_io_size is the |
421 | * preferred request size for workloads where a high number of I/O |
422 | * operations is desired. |
423 | */ |
424 | void blk_queue_io_min(struct request_queue *q, unsigned int min) |
425 | { |
426 | blk_limits_io_min(&q->limits, min); |
427 | } |
428 | EXPORT_SYMBOL(blk_queue_io_min); |
429 | |
430 | /** |
431 | * blk_queue_io_opt - set optimal request size for the queue |
432 | * @q: the request queue for the device |
433 | * @opt: optimal request size in bytes |
434 | * |
435 | * Description: |
436 | * Storage devices may report an optimal I/O size, which is the |
437 | * device's preferred unit for sustained I/O. This is rarely reported |
438 | * for disk drives. For RAID arrays it is usually the stripe width or |
439 | * the internal track size. A properly aligned multiple of |
440 | * optimal_io_size is the preferred request size for workloads where |
441 | * sustained throughput is desired. |
442 | */ |
443 | void blk_queue_io_opt(struct request_queue *q, unsigned int opt) |
444 | { |
445 | q->limits.io_opt = opt; |
446 | } |
447 | EXPORT_SYMBOL(blk_queue_io_opt); |
448 | |
449 | /* |
450 | * Returns the minimum that is _not_ zero, unless both are zero. |
451 | */ |
452 | #define min_not_zero(l, r) (l == 0) ? r : ((r == 0) ? l : min(l, r)) |
453 | |
454 | /** |
455 | * blk_queue_stack_limits - inherit underlying queue limits for stacked drivers |
456 | * @t: the stacking driver (top) |
457 | * @b: the underlying device (bottom) |
458 | **/ |
459 | void blk_queue_stack_limits(struct request_queue *t, struct request_queue *b) |
460 | { |
461 | blk_stack_limits(&t->limits, &b->limits, 0); |
462 | |
463 | if (!t->queue_lock) |
464 | WARN_ON_ONCE(1); |
465 | else if (!test_bit(QUEUE_FLAG_CLUSTER, &b->queue_flags)) { |
466 | unsigned long flags; |
467 | spin_lock_irqsave(t->queue_lock, flags); |
468 | queue_flag_clear(QUEUE_FLAG_CLUSTER, t); |
469 | spin_unlock_irqrestore(t->queue_lock, flags); |
470 | } |
471 | } |
472 | EXPORT_SYMBOL(blk_queue_stack_limits); |
473 | |
474 | /** |
475 | * blk_stack_limits - adjust queue_limits for stacked devices |
476 | * @t: the stacking driver limits (top) |
477 | * @b: the underlying queue limits (bottom) |
478 | * @offset: offset to beginning of data within component device |
479 | * |
480 | * Description: |
481 | * Merges two queue_limit structs. Returns 0 if alignment didn't |
482 | * change. Returns -1 if adding the bottom device caused |
483 | * misalignment. |
484 | */ |
485 | int blk_stack_limits(struct queue_limits *t, struct queue_limits *b, |
486 | sector_t offset) |
487 | { |
488 | t->max_sectors = min_not_zero(t->max_sectors, b->max_sectors); |
489 | t->max_hw_sectors = min_not_zero(t->max_hw_sectors, b->max_hw_sectors); |
490 | t->bounce_pfn = min_not_zero(t->bounce_pfn, b->bounce_pfn); |
491 | |
492 | t->seg_boundary_mask = min_not_zero(t->seg_boundary_mask, |
493 | b->seg_boundary_mask); |
494 | |
495 | t->max_phys_segments = min_not_zero(t->max_phys_segments, |
496 | b->max_phys_segments); |
497 | |
498 | t->max_hw_segments = min_not_zero(t->max_hw_segments, |
499 | b->max_hw_segments); |
500 | |
501 | t->max_segment_size = min_not_zero(t->max_segment_size, |
502 | b->max_segment_size); |
503 | |
504 | t->logical_block_size = max(t->logical_block_size, |
505 | b->logical_block_size); |
506 | |
507 | t->physical_block_size = max(t->physical_block_size, |
508 | b->physical_block_size); |
509 | |
510 | t->io_min = max(t->io_min, b->io_min); |
511 | t->no_cluster |= b->no_cluster; |
512 | |
513 | /* Bottom device offset aligned? */ |
514 | if (offset && |
515 | (offset & (b->physical_block_size - 1)) != b->alignment_offset) { |
516 | t->misaligned = 1; |
517 | return -1; |
518 | } |
519 | |
520 | /* If top has no alignment offset, inherit from bottom */ |
521 | if (!t->alignment_offset) |
522 | t->alignment_offset = |
523 | b->alignment_offset & (b->physical_block_size - 1); |
524 | |
525 | /* Top device aligned on logical block boundary? */ |
526 | if (t->alignment_offset & (t->logical_block_size - 1)) { |
527 | t->misaligned = 1; |
528 | return -1; |
529 | } |
530 | |
531 | /* Find lcm() of optimal I/O size */ |
532 | if (t->io_opt && b->io_opt) |
533 | t->io_opt = (t->io_opt * b->io_opt) / gcd(t->io_opt, b->io_opt); |
534 | else if (b->io_opt) |
535 | t->io_opt = b->io_opt; |
536 | |
537 | /* Verify that optimal I/O size is a multiple of io_min */ |
538 | if (t->io_min && t->io_opt % t->io_min) |
539 | return -1; |
540 | |
541 | return 0; |
542 | } |
543 | EXPORT_SYMBOL(blk_stack_limits); |
544 | |
545 | /** |
546 | * disk_stack_limits - adjust queue limits for stacked drivers |
547 | * @disk: MD/DM gendisk (top) |
548 | * @bdev: the underlying block device (bottom) |
549 | * @offset: offset to beginning of data within component device |
550 | * |
551 | * Description: |
552 | * Merges the limits for two queues. Returns 0 if alignment |
553 | * didn't change. Returns -1 if adding the bottom device caused |
554 | * misalignment. |
555 | */ |
556 | void disk_stack_limits(struct gendisk *disk, struct block_device *bdev, |
557 | sector_t offset) |
558 | { |
559 | struct request_queue *t = disk->queue; |
560 | struct request_queue *b = bdev_get_queue(bdev); |
561 | |
562 | offset += get_start_sect(bdev) << 9; |
563 | |
564 | if (blk_stack_limits(&t->limits, &b->limits, offset) < 0) { |
565 | char top[BDEVNAME_SIZE], bottom[BDEVNAME_SIZE]; |
566 | |
567 | disk_name(disk, 0, top); |
568 | bdevname(bdev, bottom); |
569 | |
570 | printk(KERN_NOTICE "%s: Warning: Device %s is misaligned\n", |
571 | top, bottom); |
572 | } |
573 | |
574 | if (!t->queue_lock) |
575 | WARN_ON_ONCE(1); |
576 | else if (!test_bit(QUEUE_FLAG_CLUSTER, &b->queue_flags)) { |
577 | unsigned long flags; |
578 | |
579 | spin_lock_irqsave(t->queue_lock, flags); |
580 | if (!test_bit(QUEUE_FLAG_CLUSTER, &b->queue_flags)) |
581 | queue_flag_clear(QUEUE_FLAG_CLUSTER, t); |
582 | spin_unlock_irqrestore(t->queue_lock, flags); |
583 | } |
584 | } |
585 | EXPORT_SYMBOL(disk_stack_limits); |
586 | |
587 | /** |
588 | * blk_queue_dma_pad - set pad mask |
589 | * @q: the request queue for the device |
590 | * @mask: pad mask |
591 | * |
592 | * Set dma pad mask. |
593 | * |
594 | * Appending pad buffer to a request modifies the last entry of a |
595 | * scatter list such that it includes the pad buffer. |
596 | **/ |
597 | void blk_queue_dma_pad(struct request_queue *q, unsigned int mask) |
598 | { |
599 | q->dma_pad_mask = mask; |
600 | } |
601 | EXPORT_SYMBOL(blk_queue_dma_pad); |
602 | |
603 | /** |
604 | * blk_queue_update_dma_pad - update pad mask |
605 | * @q: the request queue for the device |
606 | * @mask: pad mask |
607 | * |
608 | * Update dma pad mask. |
609 | * |
610 | * Appending pad buffer to a request modifies the last entry of a |
611 | * scatter list such that it includes the pad buffer. |
612 | **/ |
613 | void blk_queue_update_dma_pad(struct request_queue *q, unsigned int mask) |
614 | { |
615 | if (mask > q->dma_pad_mask) |
616 | q->dma_pad_mask = mask; |
617 | } |
618 | EXPORT_SYMBOL(blk_queue_update_dma_pad); |
619 | |
620 | /** |
621 | * blk_queue_dma_drain - Set up a drain buffer for excess dma. |
622 | * @q: the request queue for the device |
623 | * @dma_drain_needed: fn which returns non-zero if drain is necessary |
624 | * @buf: physically contiguous buffer |
625 | * @size: size of the buffer in bytes |
626 | * |
627 | * Some devices have excess DMA problems and can't simply discard (or |
628 | * zero fill) the unwanted piece of the transfer. They have to have a |
629 | * real area of memory to transfer it into. The use case for this is |
630 | * ATAPI devices in DMA mode. If the packet command causes a transfer |
631 | * bigger than the transfer size some HBAs will lock up if there |
632 | * aren't DMA elements to contain the excess transfer. What this API |
633 | * does is adjust the queue so that the buf is always appended |
634 | * silently to the scatterlist. |
635 | * |
636 | * Note: This routine adjusts max_hw_segments to make room for |
637 | * appending the drain buffer. If you call |
638 | * blk_queue_max_hw_segments() or blk_queue_max_phys_segments() after |
639 | * calling this routine, you must set the limit to one fewer than your |
640 | * device can support otherwise there won't be room for the drain |
641 | * buffer. |
642 | */ |
643 | int blk_queue_dma_drain(struct request_queue *q, |
644 | dma_drain_needed_fn *dma_drain_needed, |
645 | void *buf, unsigned int size) |
646 | { |
647 | if (queue_max_hw_segments(q) < 2 || queue_max_phys_segments(q) < 2) |
648 | return -EINVAL; |
649 | /* make room for appending the drain */ |
650 | blk_queue_max_hw_segments(q, queue_max_hw_segments(q) - 1); |
651 | blk_queue_max_phys_segments(q, queue_max_phys_segments(q) - 1); |
652 | q->dma_drain_needed = dma_drain_needed; |
653 | q->dma_drain_buffer = buf; |
654 | q->dma_drain_size = size; |
655 | |
656 | return 0; |
657 | } |
658 | EXPORT_SYMBOL_GPL(blk_queue_dma_drain); |
659 | |
660 | /** |
661 | * blk_queue_segment_boundary - set boundary rules for segment merging |
662 | * @q: the request queue for the device |
663 | * @mask: the memory boundary mask |
664 | **/ |
665 | void blk_queue_segment_boundary(struct request_queue *q, unsigned long mask) |
666 | { |
667 | if (mask < PAGE_CACHE_SIZE - 1) { |
668 | mask = PAGE_CACHE_SIZE - 1; |
669 | printk(KERN_INFO "%s: set to minimum %lx\n", |
670 | __func__, mask); |
671 | } |
672 | |
673 | q->limits.seg_boundary_mask = mask; |
674 | } |
675 | EXPORT_SYMBOL(blk_queue_segment_boundary); |
676 | |
677 | /** |
678 | * blk_queue_dma_alignment - set dma length and memory alignment |
679 | * @q: the request queue for the device |
680 | * @mask: alignment mask |
681 | * |
682 | * description: |
683 | * set required memory and length alignment for direct dma transactions. |
684 | * this is used when building direct io requests for the queue. |
685 | * |
686 | **/ |
687 | void blk_queue_dma_alignment(struct request_queue *q, int mask) |
688 | { |
689 | q->dma_alignment = mask; |
690 | } |
691 | EXPORT_SYMBOL(blk_queue_dma_alignment); |
692 | |
693 | /** |
694 | * blk_queue_update_dma_alignment - update dma length and memory alignment |
695 | * @q: the request queue for the device |
696 | * @mask: alignment mask |
697 | * |
698 | * description: |
699 | * update required memory and length alignment for direct dma transactions. |
700 | * If the requested alignment is larger than the current alignment, then |
701 | * the current queue alignment is updated to the new value, otherwise it |
702 | * is left alone. The design of this is to allow multiple objects |
703 | * (driver, device, transport etc) to set their respective |
704 | * alignments without having them interfere. |
705 | * |
706 | **/ |
707 | void blk_queue_update_dma_alignment(struct request_queue *q, int mask) |
708 | { |
709 | BUG_ON(mask > PAGE_SIZE); |
710 | |
711 | if (mask > q->dma_alignment) |
712 | q->dma_alignment = mask; |
713 | } |
714 | EXPORT_SYMBOL(blk_queue_update_dma_alignment); |
715 | |
716 | static int __init blk_settings_init(void) |
717 | { |
718 | blk_max_low_pfn = max_low_pfn - 1; |
719 | blk_max_pfn = max_pfn - 1; |
720 | return 0; |
721 | } |
722 | subsys_initcall(blk_settings_init); |
723 |
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