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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 | #include <linux/lcm.h> |
12 | #include <linux/jiffies.h> |
13 | #include <linux/gfp.h> |
14 | |
15 | #include "blk.h" |
16 | |
17 | unsigned long blk_max_low_pfn; |
18 | EXPORT_SYMBOL(blk_max_low_pfn); |
19 | |
20 | unsigned long blk_max_pfn; |
21 | |
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 | */ |
33 | void blk_queue_prep_rq(struct request_queue *q, prep_rq_fn *pfn) |
34 | { |
35 | q->prep_rq_fn = pfn; |
36 | } |
37 | EXPORT_SYMBOL(blk_queue_prep_rq); |
38 | |
39 | /** |
40 | * 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 | */ |
50 | void blk_queue_unprep_rq(struct request_queue *q, unprep_rq_fn *ufn) |
51 | { |
52 | q->unprep_rq_fn = ufn; |
53 | } |
54 | EXPORT_SYMBOL(blk_queue_unprep_rq); |
55 | |
56 | /** |
57 | * 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 | */ |
72 | void blk_queue_merge_bvec(struct request_queue *q, merge_bvec_fn *mbfn) |
73 | { |
74 | q->merge_bvec_fn = mbfn; |
75 | } |
76 | EXPORT_SYMBOL(blk_queue_merge_bvec); |
77 | |
78 | void blk_queue_softirq_done(struct request_queue *q, softirq_done_fn *fn) |
79 | { |
80 | q->softirq_done_fn = fn; |
81 | } |
82 | EXPORT_SYMBOL(blk_queue_softirq_done); |
83 | |
84 | void blk_queue_rq_timeout(struct request_queue *q, unsigned int timeout) |
85 | { |
86 | q->rq_timeout = timeout; |
87 | } |
88 | EXPORT_SYMBOL_GPL(blk_queue_rq_timeout); |
89 | |
90 | void blk_queue_rq_timed_out(struct request_queue *q, rq_timed_out_fn *fn) |
91 | { |
92 | q->rq_timed_out_fn = fn; |
93 | } |
94 | EXPORT_SYMBOL_GPL(blk_queue_rq_timed_out); |
95 | |
96 | void blk_queue_lld_busy(struct request_queue *q, lld_busy_fn *fn) |
97 | { |
98 | q->lld_busy_fn = fn; |
99 | } |
100 | EXPORT_SYMBOL_GPL(blk_queue_lld_busy); |
101 | |
102 | /** |
103 | * blk_set_default_limits - reset limits to default values |
104 | * @lim: the queue_limits structure to reset |
105 | * |
106 | * Description: |
107 | * Returns a queue_limit struct to its default state. Can be used by |
108 | * stacking drivers like DM that stage table swaps and reuse an |
109 | * existing device queue. |
110 | */ |
111 | void blk_set_default_limits(struct queue_limits *lim) |
112 | { |
113 | lim->max_segments = BLK_MAX_SEGMENTS; |
114 | lim->max_integrity_segments = 0; |
115 | lim->seg_boundary_mask = BLK_SEG_BOUNDARY_MASK; |
116 | lim->max_segment_size = BLK_MAX_SEGMENT_SIZE; |
117 | lim->max_sectors = BLK_DEF_MAX_SECTORS; |
118 | lim->max_hw_sectors = INT_MAX; |
119 | lim->max_discard_sectors = 0; |
120 | lim->discard_granularity = 0; |
121 | lim->discard_alignment = 0; |
122 | lim->discard_misaligned = 0; |
123 | lim->discard_zeroes_data = -1; |
124 | lim->logical_block_size = lim->physical_block_size = lim->io_min = 512; |
125 | lim->bounce_pfn = (unsigned long)(BLK_BOUNCE_ANY >> PAGE_SHIFT); |
126 | lim->alignment_offset = 0; |
127 | lim->io_opt = 0; |
128 | lim->misaligned = 0; |
129 | lim->cluster = 1; |
130 | } |
131 | EXPORT_SYMBOL(blk_set_default_limits); |
132 | |
133 | /** |
134 | * blk_queue_make_request - define an alternate make_request function for a device |
135 | * @q: the request queue for the device to be affected |
136 | * @mfn: the alternate make_request function |
137 | * |
138 | * Description: |
139 | * The normal way for &struct bios to be passed to a device |
140 | * driver is for them to be collected into requests on a request |
141 | * queue, and then to allow the device driver to select requests |
142 | * off that queue when it is ready. This works well for many block |
143 | * devices. However some block devices (typically virtual devices |
144 | * such as md or lvm) do not benefit from the processing on the |
145 | * request queue, and are served best by having the requests passed |
146 | * directly to them. This can be achieved by providing a function |
147 | * to blk_queue_make_request(). |
148 | * |
149 | * Caveat: |
150 | * The driver that does this *must* be able to deal appropriately |
151 | * with buffers in "highmemory". This can be accomplished by either calling |
152 | * __bio_kmap_atomic() to get a temporary kernel mapping, or by calling |
153 | * blk_queue_bounce() to create a buffer in normal memory. |
154 | **/ |
155 | void blk_queue_make_request(struct request_queue *q, make_request_fn *mfn) |
156 | { |
157 | /* |
158 | * set defaults |
159 | */ |
160 | q->nr_requests = BLKDEV_MAX_RQ; |
161 | |
162 | q->make_request_fn = mfn; |
163 | blk_queue_dma_alignment(q, 511); |
164 | blk_queue_congestion_threshold(q); |
165 | q->nr_batching = BLK_BATCH_REQ; |
166 | |
167 | q->unplug_thresh = 4; /* hmm */ |
168 | q->unplug_delay = msecs_to_jiffies(3); /* 3 milliseconds */ |
169 | if (q->unplug_delay == 0) |
170 | q->unplug_delay = 1; |
171 | |
172 | q->unplug_timer.function = blk_unplug_timeout; |
173 | q->unplug_timer.data = (unsigned long)q; |
174 | |
175 | blk_set_default_limits(&q->limits); |
176 | blk_queue_max_hw_sectors(q, BLK_SAFE_MAX_SECTORS); |
177 | |
178 | /* |
179 | * If the caller didn't supply a lock, fall back to our embedded |
180 | * per-queue locks |
181 | */ |
182 | if (!q->queue_lock) |
183 | q->queue_lock = &q->__queue_lock; |
184 | |
185 | /* |
186 | * by default assume old behaviour and bounce for any highmem page |
187 | */ |
188 | blk_queue_bounce_limit(q, BLK_BOUNCE_HIGH); |
189 | } |
190 | EXPORT_SYMBOL(blk_queue_make_request); |
191 | |
192 | /** |
193 | * blk_queue_bounce_limit - set bounce buffer limit for queue |
194 | * @q: the request queue for the device |
195 | * @dma_mask: the maximum address the device can handle |
196 | * |
197 | * Description: |
198 | * Different hardware can have different requirements as to what pages |
199 | * it can do I/O directly to. A low level driver can call |
200 | * blk_queue_bounce_limit to have lower memory pages allocated as bounce |
201 | * buffers for doing I/O to pages residing above @dma_mask. |
202 | **/ |
203 | void blk_queue_bounce_limit(struct request_queue *q, u64 dma_mask) |
204 | { |
205 | unsigned long b_pfn = dma_mask >> PAGE_SHIFT; |
206 | int dma = 0; |
207 | |
208 | q->bounce_gfp = GFP_NOIO; |
209 | #if BITS_PER_LONG == 64 |
210 | /* |
211 | * Assume anything <= 4GB can be handled by IOMMU. Actually |
212 | * some IOMMUs can handle everything, but I don't know of a |
213 | * way to test this here. |
214 | */ |
215 | if (b_pfn < (min_t(u64, 0xffffffffUL, BLK_BOUNCE_HIGH) >> PAGE_SHIFT)) |
216 | dma = 1; |
217 | q->limits.bounce_pfn = max(max_low_pfn, b_pfn); |
218 | #else |
219 | if (b_pfn < blk_max_low_pfn) |
220 | dma = 1; |
221 | q->limits.bounce_pfn = b_pfn; |
222 | #endif |
223 | if (dma) { |
224 | init_emergency_isa_pool(); |
225 | q->bounce_gfp = GFP_NOIO | GFP_DMA; |
226 | q->limits.bounce_pfn = b_pfn; |
227 | } |
228 | } |
229 | EXPORT_SYMBOL(blk_queue_bounce_limit); |
230 | |
231 | /** |
232 | * blk_limits_max_hw_sectors - set hard and soft limit of max sectors for request |
233 | * @limits: the queue limits |
234 | * @max_hw_sectors: max hardware sectors in the usual 512b unit |
235 | * |
236 | * Description: |
237 | * Enables a low level driver to set a hard upper limit, |
238 | * max_hw_sectors, on the size of requests. max_hw_sectors is set by |
239 | * the device driver based upon the combined capabilities of I/O |
240 | * controller and storage device. |
241 | * |
242 | * max_sectors is a soft limit imposed by the block layer for |
243 | * filesystem type requests. This value can be overridden on a |
244 | * per-device basis in /sys/block/<device>/queue/max_sectors_kb. |
245 | * The soft limit can not exceed max_hw_sectors. |
246 | **/ |
247 | void blk_limits_max_hw_sectors(struct queue_limits *limits, unsigned int max_hw_sectors) |
248 | { |
249 | if ((max_hw_sectors << 9) < PAGE_CACHE_SIZE) { |
250 | max_hw_sectors = 1 << (PAGE_CACHE_SHIFT - 9); |
251 | printk(KERN_INFO "%s: set to minimum %d\n", |
252 | __func__, max_hw_sectors); |
253 | } |
254 | |
255 | limits->max_hw_sectors = max_hw_sectors; |
256 | limits->max_sectors = min_t(unsigned int, max_hw_sectors, |
257 | BLK_DEF_MAX_SECTORS); |
258 | } |
259 | EXPORT_SYMBOL(blk_limits_max_hw_sectors); |
260 | |
261 | /** |
262 | * blk_queue_max_hw_sectors - set max sectors for a request for this queue |
263 | * @q: the request queue for the device |
264 | * @max_hw_sectors: max hardware sectors in the usual 512b unit |
265 | * |
266 | * Description: |
267 | * See description for blk_limits_max_hw_sectors(). |
268 | **/ |
269 | void blk_queue_max_hw_sectors(struct request_queue *q, unsigned int max_hw_sectors) |
270 | { |
271 | blk_limits_max_hw_sectors(&q->limits, max_hw_sectors); |
272 | } |
273 | EXPORT_SYMBOL(blk_queue_max_hw_sectors); |
274 | |
275 | /** |
276 | * blk_queue_max_discard_sectors - set max sectors for a single discard |
277 | * @q: the request queue for the device |
278 | * @max_discard_sectors: maximum number of sectors to discard |
279 | **/ |
280 | void blk_queue_max_discard_sectors(struct request_queue *q, |
281 | unsigned int max_discard_sectors) |
282 | { |
283 | q->limits.max_discard_sectors = max_discard_sectors; |
284 | } |
285 | EXPORT_SYMBOL(blk_queue_max_discard_sectors); |
286 | |
287 | /** |
288 | * blk_queue_max_segments - set max hw segments for a request for this queue |
289 | * @q: the request queue for the device |
290 | * @max_segments: max number of segments |
291 | * |
292 | * Description: |
293 | * Enables a low level driver to set an upper limit on the number of |
294 | * hw data segments in a request. |
295 | **/ |
296 | void blk_queue_max_segments(struct request_queue *q, unsigned short max_segments) |
297 | { |
298 | if (!max_segments) { |
299 | max_segments = 1; |
300 | printk(KERN_INFO "%s: set to minimum %d\n", |
301 | __func__, max_segments); |
302 | } |
303 | |
304 | q->limits.max_segments = max_segments; |
305 | } |
306 | EXPORT_SYMBOL(blk_queue_max_segments); |
307 | |
308 | /** |
309 | * blk_queue_max_segment_size - set max segment size for blk_rq_map_sg |
310 | * @q: the request queue for the device |
311 | * @max_size: max size of segment in bytes |
312 | * |
313 | * Description: |
314 | * Enables a low level driver to set an upper limit on the size of a |
315 | * coalesced segment |
316 | **/ |
317 | void blk_queue_max_segment_size(struct request_queue *q, unsigned int max_size) |
318 | { |
319 | if (max_size < PAGE_CACHE_SIZE) { |
320 | max_size = PAGE_CACHE_SIZE; |
321 | printk(KERN_INFO "%s: set to minimum %d\n", |
322 | __func__, max_size); |
323 | } |
324 | |
325 | q->limits.max_segment_size = max_size; |
326 | } |
327 | EXPORT_SYMBOL(blk_queue_max_segment_size); |
328 | |
329 | /** |
330 | * blk_queue_logical_block_size - set logical block size for the queue |
331 | * @q: the request queue for the device |
332 | * @size: the logical block size, in bytes |
333 | * |
334 | * Description: |
335 | * This should be set to the lowest possible block size that the |
336 | * storage device can address. The default of 512 covers most |
337 | * hardware. |
338 | **/ |
339 | void blk_queue_logical_block_size(struct request_queue *q, unsigned short size) |
340 | { |
341 | q->limits.logical_block_size = size; |
342 | |
343 | if (q->limits.physical_block_size < size) |
344 | q->limits.physical_block_size = size; |
345 | |
346 | if (q->limits.io_min < q->limits.physical_block_size) |
347 | q->limits.io_min = q->limits.physical_block_size; |
348 | } |
349 | EXPORT_SYMBOL(blk_queue_logical_block_size); |
350 | |
351 | /** |
352 | * blk_queue_physical_block_size - set physical block size for the queue |
353 | * @q: the request queue for the device |
354 | * @size: the physical block size, in bytes |
355 | * |
356 | * Description: |
357 | * This should be set to the lowest possible sector size that the |
358 | * hardware can operate on without reverting to read-modify-write |
359 | * operations. |
360 | */ |
361 | void blk_queue_physical_block_size(struct request_queue *q, unsigned int size) |
362 | { |
363 | q->limits.physical_block_size = size; |
364 | |
365 | if (q->limits.physical_block_size < q->limits.logical_block_size) |
366 | q->limits.physical_block_size = q->limits.logical_block_size; |
367 | |
368 | if (q->limits.io_min < q->limits.physical_block_size) |
369 | q->limits.io_min = q->limits.physical_block_size; |
370 | } |
371 | EXPORT_SYMBOL(blk_queue_physical_block_size); |
372 | |
373 | /** |
374 | * blk_queue_alignment_offset - set physical block alignment offset |
375 | * @q: the request queue for the device |
376 | * @offset: alignment offset in bytes |
377 | * |
378 | * Description: |
379 | * Some devices are naturally misaligned to compensate for things like |
380 | * the legacy DOS partition table 63-sector offset. Low-level drivers |
381 | * should call this function for devices whose first sector is not |
382 | * naturally aligned. |
383 | */ |
384 | void blk_queue_alignment_offset(struct request_queue *q, unsigned int offset) |
385 | { |
386 | q->limits.alignment_offset = |
387 | offset & (q->limits.physical_block_size - 1); |
388 | q->limits.misaligned = 0; |
389 | } |
390 | EXPORT_SYMBOL(blk_queue_alignment_offset); |
391 | |
392 | /** |
393 | * blk_limits_io_min - set minimum request size for a device |
394 | * @limits: the queue limits |
395 | * @min: smallest I/O size in bytes |
396 | * |
397 | * Description: |
398 | * Some devices have an internal block size bigger than the reported |
399 | * hardware sector size. This function can be used to signal the |
400 | * smallest I/O the device can perform without incurring a performance |
401 | * penalty. |
402 | */ |
403 | void blk_limits_io_min(struct queue_limits *limits, unsigned int min) |
404 | { |
405 | limits->io_min = min; |
406 | |
407 | if (limits->io_min < limits->logical_block_size) |
408 | limits->io_min = limits->logical_block_size; |
409 | |
410 | if (limits->io_min < limits->physical_block_size) |
411 | limits->io_min = limits->physical_block_size; |
412 | } |
413 | EXPORT_SYMBOL(blk_limits_io_min); |
414 | |
415 | /** |
416 | * blk_queue_io_min - set minimum request size for the queue |
417 | * @q: the request queue for the device |
418 | * @min: smallest I/O size in bytes |
419 | * |
420 | * Description: |
421 | * Storage devices may report a granularity or preferred minimum I/O |
422 | * size which is the smallest request the device can perform without |
423 | * incurring a performance penalty. For disk drives this is often the |
424 | * physical block size. For RAID arrays it is often the stripe chunk |
425 | * size. A properly aligned multiple of minimum_io_size is the |
426 | * preferred request size for workloads where a high number of I/O |
427 | * operations is desired. |
428 | */ |
429 | void blk_queue_io_min(struct request_queue *q, unsigned int min) |
430 | { |
431 | blk_limits_io_min(&q->limits, min); |
432 | } |
433 | EXPORT_SYMBOL(blk_queue_io_min); |
434 | |
435 | /** |
436 | * blk_limits_io_opt - set optimal request size for a device |
437 | * @limits: the queue limits |
438 | * @opt: smallest I/O size in bytes |
439 | * |
440 | * Description: |
441 | * Storage devices may report an optimal I/O size, which is the |
442 | * device's preferred unit for sustained I/O. This is rarely reported |
443 | * for disk drives. For RAID arrays it is usually the stripe width or |
444 | * the internal track size. A properly aligned multiple of |
445 | * optimal_io_size is the preferred request size for workloads where |
446 | * sustained throughput is desired. |
447 | */ |
448 | void blk_limits_io_opt(struct queue_limits *limits, unsigned int opt) |
449 | { |
450 | limits->io_opt = opt; |
451 | } |
452 | EXPORT_SYMBOL(blk_limits_io_opt); |
453 | |
454 | /** |
455 | * blk_queue_io_opt - set optimal request size for the queue |
456 | * @q: the request queue for the device |
457 | * @opt: optimal request size in bytes |
458 | * |
459 | * Description: |
460 | * Storage devices may report an optimal I/O size, which is the |
461 | * device's preferred unit for sustained I/O. This is rarely reported |
462 | * for disk drives. For RAID arrays it is usually the stripe width or |
463 | * the internal track size. A properly aligned multiple of |
464 | * optimal_io_size is the preferred request size for workloads where |
465 | * sustained throughput is desired. |
466 | */ |
467 | void blk_queue_io_opt(struct request_queue *q, unsigned int opt) |
468 | { |
469 | blk_limits_io_opt(&q->limits, opt); |
470 | } |
471 | EXPORT_SYMBOL(blk_queue_io_opt); |
472 | |
473 | /** |
474 | * blk_queue_stack_limits - inherit underlying queue limits for stacked drivers |
475 | * @t: the stacking driver (top) |
476 | * @b: the underlying device (bottom) |
477 | **/ |
478 | void blk_queue_stack_limits(struct request_queue *t, struct request_queue *b) |
479 | { |
480 | blk_stack_limits(&t->limits, &b->limits, 0); |
481 | } |
482 | EXPORT_SYMBOL(blk_queue_stack_limits); |
483 | |
484 | /** |
485 | * blk_stack_limits - adjust queue_limits for stacked devices |
486 | * @t: the stacking driver limits (top device) |
487 | * @b: the underlying queue limits (bottom, component device) |
488 | * @start: first data sector within component device |
489 | * |
490 | * Description: |
491 | * This function is used by stacking drivers like MD and DM to ensure |
492 | * that all component devices have compatible block sizes and |
493 | * alignments. The stacking driver must provide a queue_limits |
494 | * struct (top) and then iteratively call the stacking function for |
495 | * all component (bottom) devices. The stacking function will |
496 | * attempt to combine the values and ensure proper alignment. |
497 | * |
498 | * Returns 0 if the top and bottom queue_limits are compatible. The |
499 | * top device's block sizes and alignment offsets may be adjusted to |
500 | * ensure alignment with the bottom device. If no compatible sizes |
501 | * and alignments exist, -1 is returned and the resulting top |
502 | * queue_limits will have the misaligned flag set to indicate that |
503 | * the alignment_offset is undefined. |
504 | */ |
505 | int blk_stack_limits(struct queue_limits *t, struct queue_limits *b, |
506 | sector_t start) |
507 | { |
508 | unsigned int top, bottom, alignment, ret = 0; |
509 | |
510 | t->max_sectors = min_not_zero(t->max_sectors, b->max_sectors); |
511 | t->max_hw_sectors = min_not_zero(t->max_hw_sectors, b->max_hw_sectors); |
512 | t->bounce_pfn = min_not_zero(t->bounce_pfn, b->bounce_pfn); |
513 | |
514 | t->seg_boundary_mask = min_not_zero(t->seg_boundary_mask, |
515 | b->seg_boundary_mask); |
516 | |
517 | t->max_segments = min_not_zero(t->max_segments, b->max_segments); |
518 | t->max_integrity_segments = min_not_zero(t->max_integrity_segments, |
519 | b->max_integrity_segments); |
520 | |
521 | t->max_segment_size = min_not_zero(t->max_segment_size, |
522 | b->max_segment_size); |
523 | |
524 | t->misaligned |= b->misaligned; |
525 | |
526 | alignment = queue_limit_alignment_offset(b, start); |
527 | |
528 | /* Bottom device has different alignment. Check that it is |
529 | * compatible with the current top alignment. |
530 | */ |
531 | if (t->alignment_offset != alignment) { |
532 | |
533 | top = max(t->physical_block_size, t->io_min) |
534 | + t->alignment_offset; |
535 | bottom = max(b->physical_block_size, b->io_min) + alignment; |
536 | |
537 | /* Verify that top and bottom intervals line up */ |
538 | if (max(top, bottom) & (min(top, bottom) - 1)) { |
539 | t->misaligned = 1; |
540 | ret = -1; |
541 | } |
542 | } |
543 | |
544 | t->logical_block_size = max(t->logical_block_size, |
545 | b->logical_block_size); |
546 | |
547 | t->physical_block_size = max(t->physical_block_size, |
548 | b->physical_block_size); |
549 | |
550 | t->io_min = max(t->io_min, b->io_min); |
551 | t->io_opt = lcm(t->io_opt, b->io_opt); |
552 | |
553 | t->cluster &= b->cluster; |
554 | t->discard_zeroes_data &= b->discard_zeroes_data; |
555 | |
556 | /* Physical block size a multiple of the logical block size? */ |
557 | if (t->physical_block_size & (t->logical_block_size - 1)) { |
558 | t->physical_block_size = t->logical_block_size; |
559 | t->misaligned = 1; |
560 | ret = -1; |
561 | } |
562 | |
563 | /* Minimum I/O a multiple of the physical block size? */ |
564 | if (t->io_min & (t->physical_block_size - 1)) { |
565 | t->io_min = t->physical_block_size; |
566 | t->misaligned = 1; |
567 | ret = -1; |
568 | } |
569 | |
570 | /* Optimal I/O a multiple of the physical block size? */ |
571 | if (t->io_opt & (t->physical_block_size - 1)) { |
572 | t->io_opt = 0; |
573 | t->misaligned = 1; |
574 | ret = -1; |
575 | } |
576 | |
577 | /* Find lowest common alignment_offset */ |
578 | t->alignment_offset = lcm(t->alignment_offset, alignment) |
579 | & (max(t->physical_block_size, t->io_min) - 1); |
580 | |
581 | /* Verify that new alignment_offset is on a logical block boundary */ |
582 | if (t->alignment_offset & (t->logical_block_size - 1)) { |
583 | t->misaligned = 1; |
584 | ret = -1; |
585 | } |
586 | |
587 | /* Discard alignment and granularity */ |
588 | if (b->discard_granularity) { |
589 | alignment = queue_limit_discard_alignment(b, start); |
590 | |
591 | if (t->discard_granularity != 0 && |
592 | t->discard_alignment != alignment) { |
593 | top = t->discard_granularity + t->discard_alignment; |
594 | bottom = b->discard_granularity + alignment; |
595 | |
596 | /* Verify that top and bottom intervals line up */ |
597 | if (max(top, bottom) & (min(top, bottom) - 1)) |
598 | t->discard_misaligned = 1; |
599 | } |
600 | |
601 | t->max_discard_sectors = min_not_zero(t->max_discard_sectors, |
602 | b->max_discard_sectors); |
603 | t->discard_granularity = max(t->discard_granularity, |
604 | b->discard_granularity); |
605 | t->discard_alignment = lcm(t->discard_alignment, alignment) & |
606 | (t->discard_granularity - 1); |
607 | } |
608 | |
609 | return ret; |
610 | } |
611 | EXPORT_SYMBOL(blk_stack_limits); |
612 | |
613 | /** |
614 | * bdev_stack_limits - adjust queue limits for stacked drivers |
615 | * @t: the stacking driver limits (top device) |
616 | * @bdev: the component block_device (bottom) |
617 | * @start: first data sector within component device |
618 | * |
619 | * Description: |
620 | * Merges queue limits for a top device and a block_device. Returns |
621 | * 0 if alignment didn't change. Returns -1 if adding the bottom |
622 | * device caused misalignment. |
623 | */ |
624 | int bdev_stack_limits(struct queue_limits *t, struct block_device *bdev, |
625 | sector_t start) |
626 | { |
627 | struct request_queue *bq = bdev_get_queue(bdev); |
628 | |
629 | start += get_start_sect(bdev); |
630 | |
631 | return blk_stack_limits(t, &bq->limits, start); |
632 | } |
633 | EXPORT_SYMBOL(bdev_stack_limits); |
634 | |
635 | /** |
636 | * disk_stack_limits - adjust queue limits for stacked drivers |
637 | * @disk: MD/DM gendisk (top) |
638 | * @bdev: the underlying block device (bottom) |
639 | * @offset: offset to beginning of data within component device |
640 | * |
641 | * Description: |
642 | * Merges the limits for a top level gendisk and a bottom level |
643 | * block_device. |
644 | */ |
645 | void disk_stack_limits(struct gendisk *disk, struct block_device *bdev, |
646 | sector_t offset) |
647 | { |
648 | struct request_queue *t = disk->queue; |
649 | |
650 | if (bdev_stack_limits(&t->limits, bdev, offset >> 9) < 0) { |
651 | char top[BDEVNAME_SIZE], bottom[BDEVNAME_SIZE]; |
652 | |
653 | disk_name(disk, 0, top); |
654 | bdevname(bdev, bottom); |
655 | |
656 | printk(KERN_NOTICE "%s: Warning: Device %s is misaligned\n", |
657 | top, bottom); |
658 | } |
659 | } |
660 | EXPORT_SYMBOL(disk_stack_limits); |
661 | |
662 | /** |
663 | * blk_queue_dma_pad - set pad mask |
664 | * @q: the request queue for the device |
665 | * @mask: pad mask |
666 | * |
667 | * Set dma pad mask. |
668 | * |
669 | * Appending pad buffer to a request modifies the last entry of a |
670 | * scatter list such that it includes the pad buffer. |
671 | **/ |
672 | void blk_queue_dma_pad(struct request_queue *q, unsigned int mask) |
673 | { |
674 | q->dma_pad_mask = mask; |
675 | } |
676 | EXPORT_SYMBOL(blk_queue_dma_pad); |
677 | |
678 | /** |
679 | * blk_queue_update_dma_pad - update pad mask |
680 | * @q: the request queue for the device |
681 | * @mask: pad mask |
682 | * |
683 | * Update dma pad mask. |
684 | * |
685 | * Appending pad buffer to a request modifies the last entry of a |
686 | * scatter list such that it includes the pad buffer. |
687 | **/ |
688 | void blk_queue_update_dma_pad(struct request_queue *q, unsigned int mask) |
689 | { |
690 | if (mask > q->dma_pad_mask) |
691 | q->dma_pad_mask = mask; |
692 | } |
693 | EXPORT_SYMBOL(blk_queue_update_dma_pad); |
694 | |
695 | /** |
696 | * blk_queue_dma_drain - Set up a drain buffer for excess dma. |
697 | * @q: the request queue for the device |
698 | * @dma_drain_needed: fn which returns non-zero if drain is necessary |
699 | * @buf: physically contiguous buffer |
700 | * @size: size of the buffer in bytes |
701 | * |
702 | * Some devices have excess DMA problems and can't simply discard (or |
703 | * zero fill) the unwanted piece of the transfer. They have to have a |
704 | * real area of memory to transfer it into. The use case for this is |
705 | * ATAPI devices in DMA mode. If the packet command causes a transfer |
706 | * bigger than the transfer size some HBAs will lock up if there |
707 | * aren't DMA elements to contain the excess transfer. What this API |
708 | * does is adjust the queue so that the buf is always appended |
709 | * silently to the scatterlist. |
710 | * |
711 | * Note: This routine adjusts max_hw_segments to make room for appending |
712 | * the drain buffer. If you call blk_queue_max_segments() after calling |
713 | * this routine, you must set the limit to one fewer than your device |
714 | * can support otherwise there won't be room for the drain buffer. |
715 | */ |
716 | int blk_queue_dma_drain(struct request_queue *q, |
717 | dma_drain_needed_fn *dma_drain_needed, |
718 | void *buf, unsigned int size) |
719 | { |
720 | if (queue_max_segments(q) < 2) |
721 | return -EINVAL; |
722 | /* make room for appending the drain */ |
723 | blk_queue_max_segments(q, queue_max_segments(q) - 1); |
724 | q->dma_drain_needed = dma_drain_needed; |
725 | q->dma_drain_buffer = buf; |
726 | q->dma_drain_size = size; |
727 | |
728 | return 0; |
729 | } |
730 | EXPORT_SYMBOL_GPL(blk_queue_dma_drain); |
731 | |
732 | /** |
733 | * blk_queue_segment_boundary - set boundary rules for segment merging |
734 | * @q: the request queue for the device |
735 | * @mask: the memory boundary mask |
736 | **/ |
737 | void blk_queue_segment_boundary(struct request_queue *q, unsigned long mask) |
738 | { |
739 | if (mask < PAGE_CACHE_SIZE - 1) { |
740 | mask = PAGE_CACHE_SIZE - 1; |
741 | printk(KERN_INFO "%s: set to minimum %lx\n", |
742 | __func__, mask); |
743 | } |
744 | |
745 | q->limits.seg_boundary_mask = mask; |
746 | } |
747 | EXPORT_SYMBOL(blk_queue_segment_boundary); |
748 | |
749 | /** |
750 | * blk_queue_dma_alignment - set dma length and memory alignment |
751 | * @q: the request queue for the device |
752 | * @mask: alignment mask |
753 | * |
754 | * description: |
755 | * set required memory and length alignment for direct dma transactions. |
756 | * this is used when building direct io requests for the queue. |
757 | * |
758 | **/ |
759 | void blk_queue_dma_alignment(struct request_queue *q, int mask) |
760 | { |
761 | q->dma_alignment = mask; |
762 | } |
763 | EXPORT_SYMBOL(blk_queue_dma_alignment); |
764 | |
765 | /** |
766 | * blk_queue_update_dma_alignment - update dma length and memory alignment |
767 | * @q: the request queue for the device |
768 | * @mask: alignment mask |
769 | * |
770 | * description: |
771 | * update required memory and length alignment for direct dma transactions. |
772 | * If the requested alignment is larger than the current alignment, then |
773 | * the current queue alignment is updated to the new value, otherwise it |
774 | * is left alone. The design of this is to allow multiple objects |
775 | * (driver, device, transport etc) to set their respective |
776 | * alignments without having them interfere. |
777 | * |
778 | **/ |
779 | void blk_queue_update_dma_alignment(struct request_queue *q, int mask) |
780 | { |
781 | BUG_ON(mask > PAGE_SIZE); |
782 | |
783 | if (mask > q->dma_alignment) |
784 | q->dma_alignment = mask; |
785 | } |
786 | EXPORT_SYMBOL(blk_queue_update_dma_alignment); |
787 | |
788 | /** |
789 | * blk_queue_flush - configure queue's cache flush capability |
790 | * @q: the request queue for the device |
791 | * @flush: 0, REQ_FLUSH or REQ_FLUSH | REQ_FUA |
792 | * |
793 | * Tell block layer cache flush capability of @q. If it supports |
794 | * flushing, REQ_FLUSH should be set. If it supports bypassing |
795 | * write cache for individual writes, REQ_FUA should be set. |
796 | */ |
797 | void blk_queue_flush(struct request_queue *q, unsigned int flush) |
798 | { |
799 | WARN_ON_ONCE(flush & ~(REQ_FLUSH | REQ_FUA)); |
800 | |
801 | if (WARN_ON_ONCE(!(flush & REQ_FLUSH) && (flush & REQ_FUA))) |
802 | flush &= ~REQ_FUA; |
803 | |
804 | q->flush_flags = flush & (REQ_FLUSH | REQ_FUA); |
805 | } |
806 | EXPORT_SYMBOL_GPL(blk_queue_flush); |
807 | |
808 | static int __init blk_settings_init(void) |
809 | { |
810 | blk_max_low_pfn = max_low_pfn - 1; |
811 | blk_max_pfn = max_pfn - 1; |
812 | return 0; |
813 | } |
814 | subsys_initcall(blk_settings_init); |
815 |
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