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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. |
108 | */ |
109 | void blk_set_default_limits(struct queue_limits *lim) |
110 | { |
111 | lim->max_segments = BLK_MAX_SEGMENTS; |
112 | lim->max_integrity_segments = 0; |
113 | lim->seg_boundary_mask = BLK_SEG_BOUNDARY_MASK; |
114 | lim->max_segment_size = BLK_MAX_SEGMENT_SIZE; |
115 | lim->max_sectors = lim->max_hw_sectors = BLK_SAFE_MAX_SECTORS; |
116 | lim->chunk_sectors = 0; |
117 | lim->max_write_same_sectors = 0; |
118 | lim->max_discard_sectors = 0; |
119 | lim->discard_granularity = 0; |
120 | lim->discard_alignment = 0; |
121 | lim->discard_misaligned = 0; |
122 | lim->discard_zeroes_data = 0; |
123 | lim->logical_block_size = lim->physical_block_size = lim->io_min = 512; |
124 | lim->bounce_pfn = (unsigned long)(BLK_BOUNCE_ANY >> PAGE_SHIFT); |
125 | lim->alignment_offset = 0; |
126 | lim->io_opt = 0; |
127 | lim->misaligned = 0; |
128 | lim->cluster = 1; |
129 | } |
130 | EXPORT_SYMBOL(blk_set_default_limits); |
131 | |
132 | /** |
133 | * 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 | */ |
140 | void 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; |
148 | lim->max_segment_size = UINT_MAX; |
149 | lim->max_sectors = UINT_MAX; |
150 | lim->max_write_same_sectors = UINT_MAX; |
151 | } |
152 | EXPORT_SYMBOL(blk_set_stacking_limits); |
153 | |
154 | /** |
155 | * 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 | **/ |
176 | void blk_queue_make_request(struct request_queue *q, make_request_fn *mfn) |
177 | { |
178 | /* |
179 | * set defaults |
180 | */ |
181 | q->nr_requests = BLKDEV_MAX_RQ; |
182 | |
183 | q->make_request_fn = mfn; |
184 | blk_queue_dma_alignment(q, 511); |
185 | blk_queue_congestion_threshold(q); |
186 | q->nr_batching = BLK_BATCH_REQ; |
187 | |
188 | blk_set_default_limits(&q->limits); |
189 | |
190 | /* |
191 | * by default assume old behaviour and bounce for any highmem page |
192 | */ |
193 | blk_queue_bounce_limit(q, BLK_BOUNCE_HIGH); |
194 | } |
195 | EXPORT_SYMBOL(blk_queue_make_request); |
196 | |
197 | /** |
198 | * blk_queue_bounce_limit - set bounce buffer limit for queue |
199 | * @q: the request queue for the device |
200 | * @max_addr: the maximum address the device can handle |
201 | * |
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 |
206 | * buffers for doing I/O to pages residing above @max_addr. |
207 | **/ |
208 | void blk_queue_bounce_limit(struct request_queue *q, u64 max_addr) |
209 | { |
210 | unsigned long b_pfn = max_addr >> PAGE_SHIFT; |
211 | int dma = 0; |
212 | |
213 | q->bounce_gfp = GFP_NOIO; |
214 | #if BITS_PER_LONG == 64 |
215 | /* |
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)) |
221 | dma = 1; |
222 | q->limits.bounce_pfn = max(max_low_pfn, b_pfn); |
223 | #else |
224 | if (b_pfn < blk_max_low_pfn) |
225 | dma = 1; |
226 | q->limits.bounce_pfn = b_pfn; |
227 | #endif |
228 | if (dma) { |
229 | init_emergency_isa_pool(); |
230 | q->bounce_gfp = GFP_NOIO | GFP_DMA; |
231 | q->limits.bounce_pfn = b_pfn; |
232 | } |
233 | } |
234 | EXPORT_SYMBOL(blk_queue_bounce_limit); |
235 | |
236 | /** |
237 | * blk_limits_max_hw_sectors - set hard and soft limit of max sectors for request |
238 | * @limits: the queue limits |
239 | * @max_hw_sectors: max hardware sectors in the usual 512b unit |
240 | * |
241 | * Description: |
242 | * 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 |
244 | * the device driver based upon the combined capabilities of I/O |
245 | * controller and storage device. |
246 | * |
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. |
251 | **/ |
252 | void blk_limits_max_hw_sectors(struct queue_limits *limits, unsigned int max_hw_sectors) |
253 | { |
254 | if ((max_hw_sectors << 9) < PAGE_CACHE_SIZE) { |
255 | max_hw_sectors = 1 << (PAGE_CACHE_SHIFT - 9); |
256 | printk(KERN_INFO "%s: set to minimum %d\n", |
257 | __func__, max_hw_sectors); |
258 | } |
259 | |
260 | limits->max_hw_sectors = max_hw_sectors; |
261 | limits->max_sectors = min_t(unsigned int, max_hw_sectors, |
262 | BLK_DEF_MAX_SECTORS); |
263 | } |
264 | EXPORT_SYMBOL(blk_limits_max_hw_sectors); |
265 | |
266 | /** |
267 | * blk_queue_max_hw_sectors - set max sectors for a request for this queue |
268 | * @q: the request queue for the device |
269 | * @max_hw_sectors: max hardware sectors in the usual 512b unit |
270 | * |
271 | * Description: |
272 | * See description for blk_limits_max_hw_sectors(). |
273 | **/ |
274 | void blk_queue_max_hw_sectors(struct request_queue *q, unsigned int max_hw_sectors) |
275 | { |
276 | blk_limits_max_hw_sectors(&q->limits, max_hw_sectors); |
277 | } |
278 | EXPORT_SYMBOL(blk_queue_max_hw_sectors); |
279 | |
280 | /** |
281 | * blk_queue_chunk_sectors - set size of the chunk for this queue |
282 | * @q: the request queue for the device |
283 | * @chunk_sectors: chunk sectors in the usual 512b unit |
284 | * |
285 | * Description: |
286 | * If a driver doesn't want IOs to cross a given chunk size, it can set |
287 | * this limit and prevent merging across chunks. Note that the chunk size |
288 | * must currently be a power-of-2 in sectors. Also note that the block |
289 | * layer must accept a page worth of data at any offset. So if the |
290 | * crossing of chunks is a hard limitation in the driver, it must still be |
291 | * prepared to split single page bios. |
292 | **/ |
293 | void blk_queue_chunk_sectors(struct request_queue *q, unsigned int chunk_sectors) |
294 | { |
295 | BUG_ON(!is_power_of_2(chunk_sectors)); |
296 | q->limits.chunk_sectors = chunk_sectors; |
297 | } |
298 | EXPORT_SYMBOL(blk_queue_chunk_sectors); |
299 | |
300 | /** |
301 | * blk_queue_max_discard_sectors - set max sectors for a single discard |
302 | * @q: the request queue for the device |
303 | * @max_discard_sectors: maximum number of sectors to discard |
304 | **/ |
305 | void blk_queue_max_discard_sectors(struct request_queue *q, |
306 | unsigned int max_discard_sectors) |
307 | { |
308 | q->limits.max_discard_sectors = max_discard_sectors; |
309 | } |
310 | EXPORT_SYMBOL(blk_queue_max_discard_sectors); |
311 | |
312 | /** |
313 | * blk_queue_max_write_same_sectors - set max sectors for a single write same |
314 | * @q: the request queue for the device |
315 | * @max_write_same_sectors: maximum number of sectors to write per command |
316 | **/ |
317 | void blk_queue_max_write_same_sectors(struct request_queue *q, |
318 | unsigned int max_write_same_sectors) |
319 | { |
320 | q->limits.max_write_same_sectors = max_write_same_sectors; |
321 | } |
322 | EXPORT_SYMBOL(blk_queue_max_write_same_sectors); |
323 | |
324 | /** |
325 | * blk_queue_max_segments - set max hw segments for a request for this queue |
326 | * @q: the request queue for the device |
327 | * @max_segments: max number of segments |
328 | * |
329 | * Description: |
330 | * Enables a low level driver to set an upper limit on the number of |
331 | * hw data segments in a request. |
332 | **/ |
333 | void blk_queue_max_segments(struct request_queue *q, unsigned short max_segments) |
334 | { |
335 | if (!max_segments) { |
336 | max_segments = 1; |
337 | printk(KERN_INFO "%s: set to minimum %d\n", |
338 | __func__, max_segments); |
339 | } |
340 | |
341 | q->limits.max_segments = max_segments; |
342 | } |
343 | EXPORT_SYMBOL(blk_queue_max_segments); |
344 | |
345 | /** |
346 | * blk_queue_max_segment_size - set max segment size for blk_rq_map_sg |
347 | * @q: the request queue for the device |
348 | * @max_size: max size of segment in bytes |
349 | * |
350 | * Description: |
351 | * Enables a low level driver to set an upper limit on the size of a |
352 | * coalesced segment |
353 | **/ |
354 | void blk_queue_max_segment_size(struct request_queue *q, unsigned int max_size) |
355 | { |
356 | if (max_size < PAGE_CACHE_SIZE) { |
357 | max_size = PAGE_CACHE_SIZE; |
358 | printk(KERN_INFO "%s: set to minimum %d\n", |
359 | __func__, max_size); |
360 | } |
361 | |
362 | q->limits.max_segment_size = max_size; |
363 | } |
364 | EXPORT_SYMBOL(blk_queue_max_segment_size); |
365 | |
366 | /** |
367 | * blk_queue_logical_block_size - set logical block size for the queue |
368 | * @q: the request queue for the device |
369 | * @size: the logical block size, in bytes |
370 | * |
371 | * Description: |
372 | * This should be set to the lowest possible block size that the |
373 | * storage device can address. The default of 512 covers most |
374 | * hardware. |
375 | **/ |
376 | void blk_queue_logical_block_size(struct request_queue *q, unsigned short size) |
377 | { |
378 | q->limits.logical_block_size = size; |
379 | |
380 | if (q->limits.physical_block_size < size) |
381 | q->limits.physical_block_size = size; |
382 | |
383 | if (q->limits.io_min < q->limits.physical_block_size) |
384 | q->limits.io_min = q->limits.physical_block_size; |
385 | } |
386 | EXPORT_SYMBOL(blk_queue_logical_block_size); |
387 | |
388 | /** |
389 | * blk_queue_physical_block_size - set physical block size for the queue |
390 | * @q: the request queue for the device |
391 | * @size: the physical block size, in bytes |
392 | * |
393 | * Description: |
394 | * This should be set to the lowest possible sector size that the |
395 | * hardware can operate on without reverting to read-modify-write |
396 | * operations. |
397 | */ |
398 | void blk_queue_physical_block_size(struct request_queue *q, unsigned int size) |
399 | { |
400 | q->limits.physical_block_size = size; |
401 | |
402 | if (q->limits.physical_block_size < q->limits.logical_block_size) |
403 | q->limits.physical_block_size = q->limits.logical_block_size; |
404 | |
405 | if (q->limits.io_min < q->limits.physical_block_size) |
406 | q->limits.io_min = q->limits.physical_block_size; |
407 | } |
408 | EXPORT_SYMBOL(blk_queue_physical_block_size); |
409 | |
410 | /** |
411 | * blk_queue_alignment_offset - set physical block alignment offset |
412 | * @q: the request queue for the device |
413 | * @offset: alignment offset in bytes |
414 | * |
415 | * Description: |
416 | * Some devices are naturally misaligned to compensate for things like |
417 | * the legacy DOS partition table 63-sector offset. Low-level drivers |
418 | * should call this function for devices whose first sector is not |
419 | * naturally aligned. |
420 | */ |
421 | void blk_queue_alignment_offset(struct request_queue *q, unsigned int offset) |
422 | { |
423 | q->limits.alignment_offset = |
424 | offset & (q->limits.physical_block_size - 1); |
425 | q->limits.misaligned = 0; |
426 | } |
427 | EXPORT_SYMBOL(blk_queue_alignment_offset); |
428 | |
429 | /** |
430 | * blk_limits_io_min - set minimum request size for a device |
431 | * @limits: the queue limits |
432 | * @min: smallest I/O size in bytes |
433 | * |
434 | * Description: |
435 | * Some devices have an internal block size bigger than the reported |
436 | * hardware sector size. This function can be used to signal the |
437 | * smallest I/O the device can perform without incurring a performance |
438 | * penalty. |
439 | */ |
440 | void blk_limits_io_min(struct queue_limits *limits, unsigned int min) |
441 | { |
442 | limits->io_min = min; |
443 | |
444 | if (limits->io_min < limits->logical_block_size) |
445 | limits->io_min = limits->logical_block_size; |
446 | |
447 | if (limits->io_min < limits->physical_block_size) |
448 | limits->io_min = limits->physical_block_size; |
449 | } |
450 | EXPORT_SYMBOL(blk_limits_io_min); |
451 | |
452 | /** |
453 | * blk_queue_io_min - set minimum request size for the queue |
454 | * @q: the request queue for the device |
455 | * @min: smallest I/O size in bytes |
456 | * |
457 | * Description: |
458 | * Storage devices may report a granularity or preferred minimum I/O |
459 | * size which is the smallest request the device can perform without |
460 | * incurring a performance penalty. For disk drives this is often the |
461 | * physical block size. For RAID arrays it is often the stripe chunk |
462 | * size. A properly aligned multiple of minimum_io_size is the |
463 | * preferred request size for workloads where a high number of I/O |
464 | * operations is desired. |
465 | */ |
466 | void blk_queue_io_min(struct request_queue *q, unsigned int min) |
467 | { |
468 | blk_limits_io_min(&q->limits, min); |
469 | } |
470 | EXPORT_SYMBOL(blk_queue_io_min); |
471 | |
472 | /** |
473 | * blk_limits_io_opt - set optimal request size for a device |
474 | * @limits: the queue limits |
475 | * @opt: smallest I/O size in bytes |
476 | * |
477 | * Description: |
478 | * Storage devices may report an optimal I/O size, which is the |
479 | * device's preferred unit for sustained I/O. This is rarely reported |
480 | * for disk drives. For RAID arrays it is usually the stripe width or |
481 | * the internal track size. A properly aligned multiple of |
482 | * optimal_io_size is the preferred request size for workloads where |
483 | * sustained throughput is desired. |
484 | */ |
485 | void blk_limits_io_opt(struct queue_limits *limits, unsigned int opt) |
486 | { |
487 | limits->io_opt = opt; |
488 | } |
489 | EXPORT_SYMBOL(blk_limits_io_opt); |
490 | |
491 | /** |
492 | * blk_queue_io_opt - set optimal request size for the queue |
493 | * @q: the request queue for the device |
494 | * @opt: optimal request size in bytes |
495 | * |
496 | * Description: |
497 | * Storage devices may report an optimal I/O size, which is the |
498 | * device's preferred unit for sustained I/O. This is rarely reported |
499 | * for disk drives. For RAID arrays it is usually the stripe width or |
500 | * the internal track size. A properly aligned multiple of |
501 | * optimal_io_size is the preferred request size for workloads where |
502 | * sustained throughput is desired. |
503 | */ |
504 | void blk_queue_io_opt(struct request_queue *q, unsigned int opt) |
505 | { |
506 | blk_limits_io_opt(&q->limits, opt); |
507 | } |
508 | EXPORT_SYMBOL(blk_queue_io_opt); |
509 | |
510 | /** |
511 | * blk_queue_stack_limits - inherit underlying queue limits for stacked drivers |
512 | * @t: the stacking driver (top) |
513 | * @b: the underlying device (bottom) |
514 | **/ |
515 | void blk_queue_stack_limits(struct request_queue *t, struct request_queue *b) |
516 | { |
517 | blk_stack_limits(&t->limits, &b->limits, 0); |
518 | } |
519 | EXPORT_SYMBOL(blk_queue_stack_limits); |
520 | |
521 | /** |
522 | * blk_stack_limits - adjust queue_limits for stacked devices |
523 | * @t: the stacking driver limits (top device) |
524 | * @b: the underlying queue limits (bottom, component device) |
525 | * @start: first data sector within component device |
526 | * |
527 | * Description: |
528 | * This function is used by stacking drivers like MD and DM to ensure |
529 | * that all component devices have compatible block sizes and |
530 | * alignments. The stacking driver must provide a queue_limits |
531 | * struct (top) and then iteratively call the stacking function for |
532 | * all component (bottom) devices. The stacking function will |
533 | * attempt to combine the values and ensure proper alignment. |
534 | * |
535 | * Returns 0 if the top and bottom queue_limits are compatible. The |
536 | * top device's block sizes and alignment offsets may be adjusted to |
537 | * ensure alignment with the bottom device. If no compatible sizes |
538 | * and alignments exist, -1 is returned and the resulting top |
539 | * queue_limits will have the misaligned flag set to indicate that |
540 | * the alignment_offset is undefined. |
541 | */ |
542 | int blk_stack_limits(struct queue_limits *t, struct queue_limits *b, |
543 | sector_t start) |
544 | { |
545 | unsigned int top, bottom, alignment, ret = 0; |
546 | |
547 | t->max_sectors = min_not_zero(t->max_sectors, b->max_sectors); |
548 | t->max_hw_sectors = min_not_zero(t->max_hw_sectors, b->max_hw_sectors); |
549 | t->max_write_same_sectors = min(t->max_write_same_sectors, |
550 | b->max_write_same_sectors); |
551 | t->bounce_pfn = min_not_zero(t->bounce_pfn, b->bounce_pfn); |
552 | |
553 | t->seg_boundary_mask = min_not_zero(t->seg_boundary_mask, |
554 | b->seg_boundary_mask); |
555 | |
556 | t->max_segments = min_not_zero(t->max_segments, b->max_segments); |
557 | t->max_integrity_segments = min_not_zero(t->max_integrity_segments, |
558 | b->max_integrity_segments); |
559 | |
560 | t->max_segment_size = min_not_zero(t->max_segment_size, |
561 | b->max_segment_size); |
562 | |
563 | t->misaligned |= b->misaligned; |
564 | |
565 | alignment = queue_limit_alignment_offset(b, start); |
566 | |
567 | /* Bottom device has different alignment. Check that it is |
568 | * compatible with the current top alignment. |
569 | */ |
570 | if (t->alignment_offset != alignment) { |
571 | |
572 | top = max(t->physical_block_size, t->io_min) |
573 | + t->alignment_offset; |
574 | bottom = max(b->physical_block_size, b->io_min) + alignment; |
575 | |
576 | /* Verify that top and bottom intervals line up */ |
577 | if (max(top, bottom) % min(top, bottom)) { |
578 | t->misaligned = 1; |
579 | ret = -1; |
580 | } |
581 | } |
582 | |
583 | t->logical_block_size = max(t->logical_block_size, |
584 | b->logical_block_size); |
585 | |
586 | t->physical_block_size = max(t->physical_block_size, |
587 | b->physical_block_size); |
588 | |
589 | t->io_min = max(t->io_min, b->io_min); |
590 | t->io_opt = lcm(t->io_opt, b->io_opt); |
591 | |
592 | t->cluster &= b->cluster; |
593 | t->discard_zeroes_data &= b->discard_zeroes_data; |
594 | |
595 | /* Physical block size a multiple of the logical block size? */ |
596 | if (t->physical_block_size & (t->logical_block_size - 1)) { |
597 | t->physical_block_size = t->logical_block_size; |
598 | t->misaligned = 1; |
599 | ret = -1; |
600 | } |
601 | |
602 | /* Minimum I/O a multiple of the physical block size? */ |
603 | if (t->io_min & (t->physical_block_size - 1)) { |
604 | t->io_min = t->physical_block_size; |
605 | t->misaligned = 1; |
606 | ret = -1; |
607 | } |
608 | |
609 | /* Optimal I/O a multiple of the physical block size? */ |
610 | if (t->io_opt & (t->physical_block_size - 1)) { |
611 | t->io_opt = 0; |
612 | t->misaligned = 1; |
613 | ret = -1; |
614 | } |
615 | |
616 | t->raid_partial_stripes_expensive = |
617 | max(t->raid_partial_stripes_expensive, |
618 | b->raid_partial_stripes_expensive); |
619 | |
620 | /* Find lowest common alignment_offset */ |
621 | t->alignment_offset = lcm(t->alignment_offset, alignment) |
622 | % max(t->physical_block_size, t->io_min); |
623 | |
624 | /* Verify that new alignment_offset is on a logical block boundary */ |
625 | if (t->alignment_offset & (t->logical_block_size - 1)) { |
626 | t->misaligned = 1; |
627 | ret = -1; |
628 | } |
629 | |
630 | /* Discard alignment and granularity */ |
631 | if (b->discard_granularity) { |
632 | alignment = queue_limit_discard_alignment(b, start); |
633 | |
634 | if (t->discard_granularity != 0 && |
635 | t->discard_alignment != alignment) { |
636 | top = t->discard_granularity + t->discard_alignment; |
637 | bottom = b->discard_granularity + alignment; |
638 | |
639 | /* Verify that top and bottom intervals line up */ |
640 | if ((max(top, bottom) % min(top, bottom)) != 0) |
641 | t->discard_misaligned = 1; |
642 | } |
643 | |
644 | t->max_discard_sectors = min_not_zero(t->max_discard_sectors, |
645 | b->max_discard_sectors); |
646 | t->discard_granularity = max(t->discard_granularity, |
647 | b->discard_granularity); |
648 | t->discard_alignment = lcm(t->discard_alignment, alignment) % |
649 | t->discard_granularity; |
650 | } |
651 | |
652 | return ret; |
653 | } |
654 | EXPORT_SYMBOL(blk_stack_limits); |
655 | |
656 | /** |
657 | * bdev_stack_limits - adjust queue limits for stacked drivers |
658 | * @t: the stacking driver limits (top device) |
659 | * @bdev: the component block_device (bottom) |
660 | * @start: first data sector within component device |
661 | * |
662 | * Description: |
663 | * Merges queue limits for a top device and a block_device. Returns |
664 | * 0 if alignment didn't change. Returns -1 if adding the bottom |
665 | * device caused misalignment. |
666 | */ |
667 | int bdev_stack_limits(struct queue_limits *t, struct block_device *bdev, |
668 | sector_t start) |
669 | { |
670 | struct request_queue *bq = bdev_get_queue(bdev); |
671 | |
672 | start += get_start_sect(bdev); |
673 | |
674 | return blk_stack_limits(t, &bq->limits, start); |
675 | } |
676 | EXPORT_SYMBOL(bdev_stack_limits); |
677 | |
678 | /** |
679 | * disk_stack_limits - adjust queue limits for stacked drivers |
680 | * @disk: MD/DM gendisk (top) |
681 | * @bdev: the underlying block device (bottom) |
682 | * @offset: offset to beginning of data within component device |
683 | * |
684 | * Description: |
685 | * Merges the limits for a top level gendisk and a bottom level |
686 | * block_device. |
687 | */ |
688 | void disk_stack_limits(struct gendisk *disk, struct block_device *bdev, |
689 | sector_t offset) |
690 | { |
691 | struct request_queue *t = disk->queue; |
692 | |
693 | if (bdev_stack_limits(&t->limits, bdev, offset >> 9) < 0) { |
694 | char top[BDEVNAME_SIZE], bottom[BDEVNAME_SIZE]; |
695 | |
696 | disk_name(disk, 0, top); |
697 | bdevname(bdev, bottom); |
698 | |
699 | printk(KERN_NOTICE "%s: Warning: Device %s is misaligned\n", |
700 | top, bottom); |
701 | } |
702 | } |
703 | EXPORT_SYMBOL(disk_stack_limits); |
704 | |
705 | /** |
706 | * blk_queue_dma_pad - set pad mask |
707 | * @q: the request queue for the device |
708 | * @mask: pad mask |
709 | * |
710 | * Set dma pad mask. |
711 | * |
712 | * Appending pad buffer to a request modifies the last entry of a |
713 | * scatter list such that it includes the pad buffer. |
714 | **/ |
715 | void blk_queue_dma_pad(struct request_queue *q, unsigned int mask) |
716 | { |
717 | q->dma_pad_mask = mask; |
718 | } |
719 | EXPORT_SYMBOL(blk_queue_dma_pad); |
720 | |
721 | /** |
722 | * blk_queue_update_dma_pad - update pad mask |
723 | * @q: the request queue for the device |
724 | * @mask: pad mask |
725 | * |
726 | * Update dma pad mask. |
727 | * |
728 | * Appending pad buffer to a request modifies the last entry of a |
729 | * scatter list such that it includes the pad buffer. |
730 | **/ |
731 | void blk_queue_update_dma_pad(struct request_queue *q, unsigned int mask) |
732 | { |
733 | if (mask > q->dma_pad_mask) |
734 | q->dma_pad_mask = mask; |
735 | } |
736 | EXPORT_SYMBOL(blk_queue_update_dma_pad); |
737 | |
738 | /** |
739 | * blk_queue_dma_drain - Set up a drain buffer for excess dma. |
740 | * @q: the request queue for the device |
741 | * @dma_drain_needed: fn which returns non-zero if drain is necessary |
742 | * @buf: physically contiguous buffer |
743 | * @size: size of the buffer in bytes |
744 | * |
745 | * Some devices have excess DMA problems and can't simply discard (or |
746 | * zero fill) the unwanted piece of the transfer. They have to have a |
747 | * real area of memory to transfer it into. The use case for this is |
748 | * ATAPI devices in DMA mode. If the packet command causes a transfer |
749 | * bigger than the transfer size some HBAs will lock up if there |
750 | * aren't DMA elements to contain the excess transfer. What this API |
751 | * does is adjust the queue so that the buf is always appended |
752 | * silently to the scatterlist. |
753 | * |
754 | * Note: This routine adjusts max_hw_segments to make room for appending |
755 | * the drain buffer. If you call blk_queue_max_segments() after calling |
756 | * this routine, you must set the limit to one fewer than your device |
757 | * can support otherwise there won't be room for the drain buffer. |
758 | */ |
759 | int blk_queue_dma_drain(struct request_queue *q, |
760 | dma_drain_needed_fn *dma_drain_needed, |
761 | void *buf, unsigned int size) |
762 | { |
763 | if (queue_max_segments(q) < 2) |
764 | return -EINVAL; |
765 | /* make room for appending the drain */ |
766 | blk_queue_max_segments(q, queue_max_segments(q) - 1); |
767 | q->dma_drain_needed = dma_drain_needed; |
768 | q->dma_drain_buffer = buf; |
769 | q->dma_drain_size = size; |
770 | |
771 | return 0; |
772 | } |
773 | EXPORT_SYMBOL_GPL(blk_queue_dma_drain); |
774 | |
775 | /** |
776 | * blk_queue_segment_boundary - set boundary rules for segment merging |
777 | * @q: the request queue for the device |
778 | * @mask: the memory boundary mask |
779 | **/ |
780 | void blk_queue_segment_boundary(struct request_queue *q, unsigned long mask) |
781 | { |
782 | if (mask < PAGE_CACHE_SIZE - 1) { |
783 | mask = PAGE_CACHE_SIZE - 1; |
784 | printk(KERN_INFO "%s: set to minimum %lx\n", |
785 | __func__, mask); |
786 | } |
787 | |
788 | q->limits.seg_boundary_mask = mask; |
789 | } |
790 | EXPORT_SYMBOL(blk_queue_segment_boundary); |
791 | |
792 | /** |
793 | * blk_queue_dma_alignment - set dma length and memory alignment |
794 | * @q: the request queue for the device |
795 | * @mask: alignment mask |
796 | * |
797 | * description: |
798 | * set required memory and length alignment for direct dma transactions. |
799 | * this is used when building direct io requests for the queue. |
800 | * |
801 | **/ |
802 | void blk_queue_dma_alignment(struct request_queue *q, int mask) |
803 | { |
804 | q->dma_alignment = mask; |
805 | } |
806 | EXPORT_SYMBOL(blk_queue_dma_alignment); |
807 | |
808 | /** |
809 | * blk_queue_update_dma_alignment - update dma length and memory alignment |
810 | * @q: the request queue for the device |
811 | * @mask: alignment mask |
812 | * |
813 | * description: |
814 | * update required memory and length alignment for direct dma transactions. |
815 | * If the requested alignment is larger than the current alignment, then |
816 | * the current queue alignment is updated to the new value, otherwise it |
817 | * is left alone. The design of this is to allow multiple objects |
818 | * (driver, device, transport etc) to set their respective |
819 | * alignments without having them interfere. |
820 | * |
821 | **/ |
822 | void blk_queue_update_dma_alignment(struct request_queue *q, int mask) |
823 | { |
824 | BUG_ON(mask > PAGE_SIZE); |
825 | |
826 | if (mask > q->dma_alignment) |
827 | q->dma_alignment = mask; |
828 | } |
829 | EXPORT_SYMBOL(blk_queue_update_dma_alignment); |
830 | |
831 | /** |
832 | * blk_queue_flush - configure queue's cache flush capability |
833 | * @q: the request queue for the device |
834 | * @flush: 0, REQ_FLUSH or REQ_FLUSH | REQ_FUA |
835 | * |
836 | * Tell block layer cache flush capability of @q. If it supports |
837 | * flushing, REQ_FLUSH should be set. If it supports bypassing |
838 | * write cache for individual writes, REQ_FUA should be set. |
839 | */ |
840 | void blk_queue_flush(struct request_queue *q, unsigned int flush) |
841 | { |
842 | WARN_ON_ONCE(flush & ~(REQ_FLUSH | REQ_FUA)); |
843 | |
844 | if (WARN_ON_ONCE(!(flush & REQ_FLUSH) && (flush & REQ_FUA))) |
845 | flush &= ~REQ_FUA; |
846 | |
847 | q->flush_flags = flush & (REQ_FLUSH | REQ_FUA); |
848 | } |
849 | EXPORT_SYMBOL_GPL(blk_queue_flush); |
850 | |
851 | void blk_queue_flush_queueable(struct request_queue *q, bool queueable) |
852 | { |
853 | q->flush_not_queueable = !queueable; |
854 | } |
855 | EXPORT_SYMBOL_GPL(blk_queue_flush_queueable); |
856 | |
857 | static int __init blk_settings_init(void) |
858 | { |
859 | blk_max_low_pfn = max_low_pfn - 1; |
860 | blk_max_pfn = max_pfn - 1; |
861 | return 0; |
862 | } |
863 | subsys_initcall(blk_settings_init); |
864 |
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