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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_merge_bvec - set a merge_bvec function for queue | |
38 | * @q: queue | |
39 | * @mbfn: merge_bvec_fn | |
40 | * | |
41 | * Usually queues have static limitations on the max sectors or segments that | |
42 | * we can put in a request. Stacking drivers may have some settings that | |
43 | * are dynamic, and thus we have to query the queue whether it is ok to | |
44 | * add a new bio_vec to a bio at a given offset or not. If the block device | |
45 | * has such limitations, it needs to register a merge_bvec_fn to control | |
46 | * the size of bio's sent to it. Note that a block device *must* allow a | |
47 | * single page to be added to an empty bio. The block device driver may want | |
48 | * to use the bio_split() function to deal with these bio's. By default | |
49 | * no merge_bvec_fn is defined for a queue, and only the fixed limits are | |
50 | * honored. | |
51 | */ | |
52 | void blk_queue_merge_bvec(struct request_queue *q, merge_bvec_fn *mbfn) | |
53 | { | |
54 | q->merge_bvec_fn = mbfn; | |
55 | } | |
56 | EXPORT_SYMBOL(blk_queue_merge_bvec); | |
57 | ||
58 | void blk_queue_softirq_done(struct request_queue *q, softirq_done_fn *fn) | |
59 | { | |
60 | q->softirq_done_fn = fn; | |
61 | } | |
62 | EXPORT_SYMBOL(blk_queue_softirq_done); | |
63 | ||
64 | void blk_queue_rq_timeout(struct request_queue *q, unsigned int timeout) | |
65 | { | |
66 | q->rq_timeout = timeout; | |
67 | } | |
68 | EXPORT_SYMBOL_GPL(blk_queue_rq_timeout); | |
69 | ||
70 | void blk_queue_rq_timed_out(struct request_queue *q, rq_timed_out_fn *fn) | |
71 | { | |
72 | q->rq_timed_out_fn = fn; | |
73 | } | |
74 | EXPORT_SYMBOL_GPL(blk_queue_rq_timed_out); | |
75 | ||
76 | void blk_queue_lld_busy(struct request_queue *q, lld_busy_fn *fn) | |
77 | { | |
78 | q->lld_busy_fn = fn; | |
79 | } | |
80 | EXPORT_SYMBOL_GPL(blk_queue_lld_busy); | |
81 | ||
82 | /** | |
83 | * blk_set_default_limits - reset limits to default values | |
84 | * @lim: the queue_limits structure to reset | |
85 | * | |
86 | * Description: | |
87 | * Returns a queue_limit struct to its default state. Can be used by | |
88 | * stacking drivers like DM that stage table swaps and reuse an | |
89 | * existing device queue. | |
90 | */ | |
91 | void blk_set_default_limits(struct queue_limits *lim) | |
92 | { | |
93 | lim->max_phys_segments = MAX_PHYS_SEGMENTS; | |
94 | lim->max_hw_segments = MAX_HW_SEGMENTS; | |
95 | lim->seg_boundary_mask = BLK_SEG_BOUNDARY_MASK; | |
96 | lim->max_segment_size = MAX_SEGMENT_SIZE; | |
97 | lim->max_sectors = BLK_DEF_MAX_SECTORS; | |
98 | lim->max_hw_sectors = INT_MAX; | |
99 | lim->logical_block_size = lim->physical_block_size = lim->io_min = 512; | |
100 | lim->bounce_pfn = (unsigned long)(BLK_BOUNCE_ANY >> PAGE_SHIFT); | |
101 | lim->alignment_offset = 0; | |
102 | lim->io_opt = 0; | |
103 | lim->misaligned = 0; | |
104 | lim->no_cluster = 0; | |
105 | } | |
106 | EXPORT_SYMBOL(blk_set_default_limits); | |
107 | ||
108 | /** | |
109 | * blk_queue_make_request - define an alternate make_request function for a device | |
110 | * @q: the request queue for the device to be affected | |
111 | * @mfn: the alternate make_request function | |
112 | * | |
113 | * Description: | |
114 | * The normal way for &struct bios to be passed to a device | |
115 | * driver is for them to be collected into requests on a request | |
116 | * queue, and then to allow the device driver to select requests | |
117 | * off that queue when it is ready. This works well for many block | |
118 | * devices. However some block devices (typically virtual devices | |
119 | * such as md or lvm) do not benefit from the processing on the | |
120 | * request queue, and are served best by having the requests passed | |
121 | * directly to them. This can be achieved by providing a function | |
122 | * to blk_queue_make_request(). | |
123 | * | |
124 | * Caveat: | |
125 | * The driver that does this *must* be able to deal appropriately | |
126 | * with buffers in "highmemory". This can be accomplished by either calling | |
127 | * __bio_kmap_atomic() to get a temporary kernel mapping, or by calling | |
128 | * blk_queue_bounce() to create a buffer in normal memory. | |
129 | **/ | |
130 | void blk_queue_make_request(struct request_queue *q, make_request_fn *mfn) | |
131 | { | |
132 | /* | |
133 | * set defaults | |
134 | */ | |
135 | q->nr_requests = BLKDEV_MAX_RQ; | |
136 | ||
137 | q->make_request_fn = mfn; | |
138 | blk_queue_dma_alignment(q, 511); | |
139 | blk_queue_congestion_threshold(q); | |
140 | q->nr_batching = BLK_BATCH_REQ; | |
141 | ||
142 | q->unplug_thresh = 4; /* hmm */ | |
143 | q->unplug_delay = (3 * HZ) / 1000; /* 3 milliseconds */ | |
144 | if (q->unplug_delay == 0) | |
145 | q->unplug_delay = 1; | |
146 | ||
147 | q->unplug_timer.function = blk_unplug_timeout; | |
148 | q->unplug_timer.data = (unsigned long)q; | |
149 | ||
150 | blk_set_default_limits(&q->limits); | |
151 | blk_queue_max_sectors(q, SAFE_MAX_SECTORS); | |
152 | ||
153 | /* | |
154 | * If the caller didn't supply a lock, fall back to our embedded | |
155 | * per-queue locks | |
156 | */ | |
157 | if (!q->queue_lock) | |
158 | q->queue_lock = &q->__queue_lock; | |
159 | ||
160 | /* | |
161 | * by default assume old behaviour and bounce for any highmem page | |
162 | */ | |
163 | blk_queue_bounce_limit(q, BLK_BOUNCE_HIGH); | |
164 | } | |
165 | EXPORT_SYMBOL(blk_queue_make_request); | |
166 | ||
167 | /** | |
168 | * blk_queue_bounce_limit - set bounce buffer limit for queue | |
169 | * @q: the request queue for the device | |
170 | * @dma_mask: the maximum address the device can handle | |
171 | * | |
172 | * Description: | |
173 | * Different hardware can have different requirements as to what pages | |
174 | * it can do I/O directly to. A low level driver can call | |
175 | * blk_queue_bounce_limit to have lower memory pages allocated as bounce | |
176 | * buffers for doing I/O to pages residing above @dma_mask. | |
177 | **/ | |
178 | void blk_queue_bounce_limit(struct request_queue *q, u64 dma_mask) | |
179 | { | |
180 | unsigned long b_pfn = dma_mask >> PAGE_SHIFT; | |
181 | int dma = 0; | |
182 | ||
183 | q->bounce_gfp = GFP_NOIO; | |
184 | #if BITS_PER_LONG == 64 | |
185 | /* | |
186 | * Assume anything <= 4GB can be handled by IOMMU. Actually | |
187 | * some IOMMUs can handle everything, but I don't know of a | |
188 | * way to test this here. | |
189 | */ | |
190 | if (b_pfn < (min_t(u64, 0xffffffffUL, BLK_BOUNCE_HIGH) >> PAGE_SHIFT)) | |
191 | dma = 1; | |
192 | q->limits.bounce_pfn = max_low_pfn; | |
193 | #else | |
194 | if (b_pfn < blk_max_low_pfn) | |
195 | dma = 1; | |
196 | q->limits.bounce_pfn = b_pfn; | |
197 | #endif | |
198 | if (dma) { | |
199 | init_emergency_isa_pool(); | |
200 | q->bounce_gfp = GFP_NOIO | GFP_DMA; | |
201 | q->limits.bounce_pfn = b_pfn; | |
202 | } | |
203 | } | |
204 | EXPORT_SYMBOL(blk_queue_bounce_limit); | |
205 | ||
206 | /** | |
207 | * blk_queue_max_sectors - set max sectors for a request for this queue | |
208 | * @q: the request queue for the device | |
209 | * @max_sectors: max sectors in the usual 512b unit | |
210 | * | |
211 | * Description: | |
212 | * Enables a low level driver to set an upper limit on the size of | |
213 | * received requests. | |
214 | **/ | |
215 | void blk_queue_max_sectors(struct request_queue *q, unsigned int max_sectors) | |
216 | { | |
217 | if ((max_sectors << 9) < PAGE_CACHE_SIZE) { | |
218 | max_sectors = 1 << (PAGE_CACHE_SHIFT - 9); | |
219 | printk(KERN_INFO "%s: set to minimum %d\n", | |
220 | __func__, max_sectors); | |
221 | } | |
222 | ||
223 | if (BLK_DEF_MAX_SECTORS > max_sectors) | |
224 | q->limits.max_hw_sectors = q->limits.max_sectors = max_sectors; | |
225 | else { | |
226 | q->limits.max_sectors = BLK_DEF_MAX_SECTORS; | |
227 | q->limits.max_hw_sectors = max_sectors; | |
228 | } | |
229 | } | |
230 | EXPORT_SYMBOL(blk_queue_max_sectors); | |
231 | ||
232 | void blk_queue_max_hw_sectors(struct request_queue *q, unsigned int max_sectors) | |
233 | { | |
234 | if (BLK_DEF_MAX_SECTORS > max_sectors) | |
235 | q->limits.max_hw_sectors = BLK_DEF_MAX_SECTORS; | |
236 | else | |
237 | q->limits.max_hw_sectors = max_sectors; | |
238 | } | |
239 | EXPORT_SYMBOL(blk_queue_max_hw_sectors); | |
240 | ||
241 | /** | |
242 | * blk_queue_max_phys_segments - set max phys segments for a request for this queue | |
243 | * @q: the request queue for the device | |
244 | * @max_segments: max number of segments | |
245 | * | |
246 | * Description: | |
247 | * Enables a low level driver to set an upper limit on the number of | |
248 | * physical data segments in a request. This would be the largest sized | |
249 | * scatter list the driver could handle. | |
250 | **/ | |
251 | void blk_queue_max_phys_segments(struct request_queue *q, | |
252 | unsigned short max_segments) | |
253 | { | |
254 | if (!max_segments) { | |
255 | max_segments = 1; | |
256 | printk(KERN_INFO "%s: set to minimum %d\n", | |
257 | __func__, max_segments); | |
258 | } | |
259 | ||
260 | q->limits.max_phys_segments = max_segments; | |
261 | } | |
262 | EXPORT_SYMBOL(blk_queue_max_phys_segments); | |
263 | ||
264 | /** | |
265 | * blk_queue_max_hw_segments - set max hw segments for a request for this queue | |
266 | * @q: the request queue for the device | |
267 | * @max_segments: max number of segments | |
268 | * | |
269 | * Description: | |
270 | * Enables a low level driver to set an upper limit on the number of | |
271 | * hw data segments in a request. This would be the largest number of | |
272 | * address/length pairs the host adapter can actually give at once | |
273 | * to the device. | |
274 | **/ | |
275 | void blk_queue_max_hw_segments(struct request_queue *q, | |
276 | unsigned short max_segments) | |
277 | { | |
278 | if (!max_segments) { | |
279 | max_segments = 1; | |
280 | printk(KERN_INFO "%s: set to minimum %d\n", | |
281 | __func__, max_segments); | |
282 | } | |
283 | ||
284 | q->limits.max_hw_segments = max_segments; | |
285 | } | |
286 | EXPORT_SYMBOL(blk_queue_max_hw_segments); | |
287 | ||
288 | /** | |
289 | * blk_queue_max_segment_size - set max segment size for blk_rq_map_sg | |
290 | * @q: the request queue for the device | |
291 | * @max_size: max size of segment in bytes | |
292 | * | |
293 | * Description: | |
294 | * Enables a low level driver to set an upper limit on the size of a | |
295 | * coalesced segment | |
296 | **/ | |
297 | void blk_queue_max_segment_size(struct request_queue *q, unsigned int max_size) | |
298 | { | |
299 | if (max_size < PAGE_CACHE_SIZE) { | |
300 | max_size = PAGE_CACHE_SIZE; | |
301 | printk(KERN_INFO "%s: set to minimum %d\n", | |
302 | __func__, max_size); | |
303 | } | |
304 | ||
305 | q->limits.max_segment_size = max_size; | |
306 | } | |
307 | EXPORT_SYMBOL(blk_queue_max_segment_size); | |
308 | ||
309 | /** | |
310 | * blk_queue_logical_block_size - set logical block size for the queue | |
311 | * @q: the request queue for the device | |
312 | * @size: the logical block size, in bytes | |
313 | * | |
314 | * Description: | |
315 | * This should be set to the lowest possible block size that the | |
316 | * storage device can address. The default of 512 covers most | |
317 | * hardware. | |
318 | **/ | |
319 | void blk_queue_logical_block_size(struct request_queue *q, unsigned short size) | |
320 | { | |
321 | q->limits.logical_block_size = size; | |
322 | ||
323 | if (q->limits.physical_block_size < size) | |
324 | q->limits.physical_block_size = size; | |
325 | ||
326 | if (q->limits.io_min < q->limits.physical_block_size) | |
327 | q->limits.io_min = q->limits.physical_block_size; | |
328 | } | |
329 | EXPORT_SYMBOL(blk_queue_logical_block_size); | |
330 | ||
331 | /** | |
332 | * blk_queue_physical_block_size - set physical block size for the queue | |
333 | * @q: the request queue for the device | |
334 | * @size: the physical block size, in bytes | |
335 | * | |
336 | * Description: | |
337 | * This should be set to the lowest possible sector size that the | |
338 | * hardware can operate on without reverting to read-modify-write | |
339 | * operations. | |
340 | */ | |
341 | void blk_queue_physical_block_size(struct request_queue *q, unsigned short size) | |
342 | { | |
343 | q->limits.physical_block_size = size; | |
344 | ||
345 | if (q->limits.physical_block_size < q->limits.logical_block_size) | |
346 | q->limits.physical_block_size = q->limits.logical_block_size; | |
347 | ||
348 | if (q->limits.io_min < q->limits.physical_block_size) | |
349 | q->limits.io_min = q->limits.physical_block_size; | |
350 | } | |
351 | EXPORT_SYMBOL(blk_queue_physical_block_size); | |
352 | ||
353 | /** | |
354 | * blk_queue_alignment_offset - set physical block alignment offset | |
355 | * @q: the request queue for the device | |
356 | * @offset: alignment offset in bytes | |
357 | * | |
358 | * Description: | |
359 | * Some devices are naturally misaligned to compensate for things like | |
360 | * the legacy DOS partition table 63-sector offset. Low-level drivers | |
361 | * should call this function for devices whose first sector is not | |
362 | * naturally aligned. | |
363 | */ | |
364 | void blk_queue_alignment_offset(struct request_queue *q, unsigned int offset) | |
365 | { | |
366 | q->limits.alignment_offset = | |
367 | offset & (q->limits.physical_block_size - 1); | |
368 | q->limits.misaligned = 0; | |
369 | } | |
370 | EXPORT_SYMBOL(blk_queue_alignment_offset); | |
371 | ||
372 | /** | |
373 | * blk_limits_io_min - set minimum request size for a device | |
374 | * @limits: the queue limits | |
375 | * @min: smallest I/O size in bytes | |
376 | * | |
377 | * Description: | |
378 | * Some devices have an internal block size bigger than the reported | |
379 | * hardware sector size. This function can be used to signal the | |
380 | * smallest I/O the device can perform without incurring a performance | |
381 | * penalty. | |
382 | */ | |
383 | void blk_limits_io_min(struct queue_limits *limits, unsigned int min) | |
384 | { | |
385 | limits->io_min = min; | |
386 | ||
387 | if (limits->io_min < limits->logical_block_size) | |
388 | limits->io_min = limits->logical_block_size; | |
389 | ||
390 | if (limits->io_min < limits->physical_block_size) | |
391 | limits->io_min = limits->physical_block_size; | |
392 | } | |
393 | EXPORT_SYMBOL(blk_limits_io_min); | |
394 | ||
395 | /** | |
396 | * blk_queue_io_min - set minimum request size for the queue | |
397 | * @q: the request queue for the device | |
398 | * @min: smallest I/O size in bytes | |
399 | * | |
400 | * Description: | |
401 | * Storage devices may report a granularity or preferred minimum I/O | |
402 | * size which is the smallest request the device can perform without | |
403 | * incurring a performance penalty. For disk drives this is often the | |
404 | * physical block size. For RAID arrays it is often the stripe chunk | |
405 | * size. A properly aligned multiple of minimum_io_size is the | |
406 | * preferred request size for workloads where a high number of I/O | |
407 | * operations is desired. | |
408 | */ | |
409 | void blk_queue_io_min(struct request_queue *q, unsigned int min) | |
410 | { | |
411 | blk_limits_io_min(&q->limits, min); | |
412 | } | |
413 | EXPORT_SYMBOL(blk_queue_io_min); | |
414 | ||
415 | /** | |
416 | * blk_limits_io_opt - set optimal request size for a device | |
417 | * @limits: the queue limits | |
418 | * @opt: smallest I/O size in bytes | |
419 | * | |
420 | * Description: | |
421 | * Storage devices may report an optimal I/O size, which is the | |
422 | * device's preferred unit for sustained I/O. This is rarely reported | |
423 | * for disk drives. For RAID arrays it is usually the stripe width or | |
424 | * the internal track size. A properly aligned multiple of | |
425 | * optimal_io_size is the preferred request size for workloads where | |
426 | * sustained throughput is desired. | |
427 | */ | |
428 | void blk_limits_io_opt(struct queue_limits *limits, unsigned int opt) | |
429 | { | |
430 | limits->io_opt = opt; | |
431 | } | |
432 | EXPORT_SYMBOL(blk_limits_io_opt); | |
433 | ||
434 | /** | |
435 | * blk_queue_io_opt - set optimal request size for the queue | |
436 | * @q: the request queue for the device | |
437 | * @opt: optimal request size in bytes | |
438 | * | |
439 | * Description: | |
440 | * Storage devices may report an optimal I/O size, which is the | |
441 | * device's preferred unit for sustained I/O. This is rarely reported | |
442 | * for disk drives. For RAID arrays it is usually the stripe width or | |
443 | * the internal track size. A properly aligned multiple of | |
444 | * optimal_io_size is the preferred request size for workloads where | |
445 | * sustained throughput is desired. | |
446 | */ | |
447 | void blk_queue_io_opt(struct request_queue *q, unsigned int opt) | |
448 | { | |
449 | blk_limits_io_opt(&q->limits, opt); | |
450 | } | |
451 | EXPORT_SYMBOL(blk_queue_io_opt); | |
452 | ||
453 | /* | |
454 | * Returns the minimum that is _not_ zero, unless both are zero. | |
455 | */ | |
456 | #define min_not_zero(l, r) (l == 0) ? r : ((r == 0) ? l : min(l, r)) | |
457 | ||
458 | /** | |
459 | * blk_queue_stack_limits - inherit underlying queue limits for stacked drivers | |
460 | * @t: the stacking driver (top) | |
461 | * @b: the underlying device (bottom) | |
462 | **/ | |
463 | void blk_queue_stack_limits(struct request_queue *t, struct request_queue *b) | |
464 | { | |
465 | blk_stack_limits(&t->limits, &b->limits, 0); | |
466 | ||
467 | if (!t->queue_lock) | |
468 | WARN_ON_ONCE(1); | |
469 | else if (!test_bit(QUEUE_FLAG_CLUSTER, &b->queue_flags)) { | |
470 | unsigned long flags; | |
471 | spin_lock_irqsave(t->queue_lock, flags); | |
472 | queue_flag_clear(QUEUE_FLAG_CLUSTER, t); | |
473 | spin_unlock_irqrestore(t->queue_lock, flags); | |
474 | } | |
475 | } | |
476 | EXPORT_SYMBOL(blk_queue_stack_limits); | |
477 | ||
478 | /** | |
479 | * blk_stack_limits - adjust queue_limits for stacked devices | |
480 | * @t: the stacking driver limits (top) | |
481 | * @b: the underlying queue limits (bottom) | |
482 | * @offset: offset to beginning of data within component device | |
483 | * | |
484 | * Description: | |
485 | * Merges two queue_limit structs. Returns 0 if alignment didn't | |
486 | * change. Returns -1 if adding the bottom device caused | |
487 | * misalignment. | |
488 | */ | |
489 | int blk_stack_limits(struct queue_limits *t, struct queue_limits *b, | |
490 | sector_t offset) | |
491 | { | |
492 | t->max_sectors = min_not_zero(t->max_sectors, b->max_sectors); | |
493 | t->max_hw_sectors = min_not_zero(t->max_hw_sectors, b->max_hw_sectors); | |
494 | t->bounce_pfn = min_not_zero(t->bounce_pfn, b->bounce_pfn); | |
495 | ||
496 | t->seg_boundary_mask = min_not_zero(t->seg_boundary_mask, | |
497 | b->seg_boundary_mask); | |
498 | ||
499 | t->max_phys_segments = min_not_zero(t->max_phys_segments, | |
500 | b->max_phys_segments); | |
501 | ||
502 | t->max_hw_segments = min_not_zero(t->max_hw_segments, | |
503 | b->max_hw_segments); | |
504 | ||
505 | t->max_segment_size = min_not_zero(t->max_segment_size, | |
506 | b->max_segment_size); | |
507 | ||
508 | t->logical_block_size = max(t->logical_block_size, | |
509 | b->logical_block_size); | |
510 | ||
511 | t->physical_block_size = max(t->physical_block_size, | |
512 | b->physical_block_size); | |
513 | ||
514 | t->io_min = max(t->io_min, b->io_min); | |
515 | t->no_cluster |= b->no_cluster; | |
516 | ||
517 | /* Bottom device offset aligned? */ | |
518 | if (offset && | |
519 | (offset & (b->physical_block_size - 1)) != b->alignment_offset) { | |
520 | t->misaligned = 1; | |
521 | return -1; | |
522 | } | |
523 | ||
524 | /* If top has no alignment offset, inherit from bottom */ | |
525 | if (!t->alignment_offset) | |
526 | t->alignment_offset = | |
527 | b->alignment_offset & (b->physical_block_size - 1); | |
528 | ||
529 | /* Top device aligned on logical block boundary? */ | |
530 | if (t->alignment_offset & (t->logical_block_size - 1)) { | |
531 | t->misaligned = 1; | |
532 | return -1; | |
533 | } | |
534 | ||
535 | /* Find lcm() of optimal I/O size */ | |
536 | if (t->io_opt && b->io_opt) | |
537 | t->io_opt = (t->io_opt * b->io_opt) / gcd(t->io_opt, b->io_opt); | |
538 | else if (b->io_opt) | |
539 | t->io_opt = b->io_opt; | |
540 | ||
541 | /* Verify that optimal I/O size is a multiple of io_min */ | |
542 | if (t->io_min && t->io_opt % t->io_min) | |
543 | return -1; | |
544 | ||
545 | return 0; | |
546 | } | |
547 | EXPORT_SYMBOL(blk_stack_limits); | |
548 | ||
549 | /** | |
550 | * disk_stack_limits - adjust queue limits for stacked drivers | |
551 | * @disk: MD/DM gendisk (top) | |
552 | * @bdev: the underlying block device (bottom) | |
553 | * @offset: offset to beginning of data within component device | |
554 | * | |
555 | * Description: | |
556 | * Merges the limits for two queues. Returns 0 if alignment | |
557 | * didn't change. Returns -1 if adding the bottom device caused | |
558 | * misalignment. | |
559 | */ | |
560 | void disk_stack_limits(struct gendisk *disk, struct block_device *bdev, | |
561 | sector_t offset) | |
562 | { | |
563 | struct request_queue *t = disk->queue; | |
564 | struct request_queue *b = bdev_get_queue(bdev); | |
565 | ||
566 | offset += get_start_sect(bdev) << 9; | |
567 | ||
568 | if (blk_stack_limits(&t->limits, &b->limits, offset) < 0) { | |
569 | char top[BDEVNAME_SIZE], bottom[BDEVNAME_SIZE]; | |
570 | ||
571 | disk_name(disk, 0, top); | |
572 | bdevname(bdev, bottom); | |
573 | ||
574 | printk(KERN_NOTICE "%s: Warning: Device %s is misaligned\n", | |
575 | top, bottom); | |
576 | } | |
577 | ||
578 | if (!t->queue_lock) | |
579 | WARN_ON_ONCE(1); | |
580 | else if (!test_bit(QUEUE_FLAG_CLUSTER, &b->queue_flags)) { | |
581 | unsigned long flags; | |
582 | ||
583 | spin_lock_irqsave(t->queue_lock, flags); | |
584 | if (!test_bit(QUEUE_FLAG_CLUSTER, &b->queue_flags)) | |
585 | queue_flag_clear(QUEUE_FLAG_CLUSTER, t); | |
586 | spin_unlock_irqrestore(t->queue_lock, flags); | |
587 | } | |
588 | } | |
589 | EXPORT_SYMBOL(disk_stack_limits); | |
590 | ||
591 | /** | |
592 | * blk_queue_dma_pad - set pad mask | |
593 | * @q: the request queue for the device | |
594 | * @mask: pad mask | |
595 | * | |
596 | * Set dma pad mask. | |
597 | * | |
598 | * Appending pad buffer to a request modifies the last entry of a | |
599 | * scatter list such that it includes the pad buffer. | |
600 | **/ | |
601 | void blk_queue_dma_pad(struct request_queue *q, unsigned int mask) | |
602 | { | |
603 | q->dma_pad_mask = mask; | |
604 | } | |
605 | EXPORT_SYMBOL(blk_queue_dma_pad); | |
606 | ||
607 | /** | |
608 | * blk_queue_update_dma_pad - update pad mask | |
609 | * @q: the request queue for the device | |
610 | * @mask: pad mask | |
611 | * | |
612 | * Update dma pad mask. | |
613 | * | |
614 | * Appending pad buffer to a request modifies the last entry of a | |
615 | * scatter list such that it includes the pad buffer. | |
616 | **/ | |
617 | void blk_queue_update_dma_pad(struct request_queue *q, unsigned int mask) | |
618 | { | |
619 | if (mask > q->dma_pad_mask) | |
620 | q->dma_pad_mask = mask; | |
621 | } | |
622 | EXPORT_SYMBOL(blk_queue_update_dma_pad); | |
623 | ||
624 | /** | |
625 | * blk_queue_dma_drain - Set up a drain buffer for excess dma. | |
626 | * @q: the request queue for the device | |
627 | * @dma_drain_needed: fn which returns non-zero if drain is necessary | |
628 | * @buf: physically contiguous buffer | |
629 | * @size: size of the buffer in bytes | |
630 | * | |
631 | * Some devices have excess DMA problems and can't simply discard (or | |
632 | * zero fill) the unwanted piece of the transfer. They have to have a | |
633 | * real area of memory to transfer it into. The use case for this is | |
634 | * ATAPI devices in DMA mode. If the packet command causes a transfer | |
635 | * bigger than the transfer size some HBAs will lock up if there | |
636 | * aren't DMA elements to contain the excess transfer. What this API | |
637 | * does is adjust the queue so that the buf is always appended | |
638 | * silently to the scatterlist. | |
639 | * | |
640 | * Note: This routine adjusts max_hw_segments to make room for | |
641 | * appending the drain buffer. If you call | |
642 | * blk_queue_max_hw_segments() or blk_queue_max_phys_segments() after | |
643 | * calling this routine, you must set the limit to one fewer than your | |
644 | * device can support otherwise there won't be room for the drain | |
645 | * buffer. | |
646 | */ | |
647 | int blk_queue_dma_drain(struct request_queue *q, | |
648 | dma_drain_needed_fn *dma_drain_needed, | |
649 | void *buf, unsigned int size) | |
650 | { | |
651 | if (queue_max_hw_segments(q) < 2 || queue_max_phys_segments(q) < 2) | |
652 | return -EINVAL; | |
653 | /* make room for appending the drain */ | |
654 | blk_queue_max_hw_segments(q, queue_max_hw_segments(q) - 1); | |
655 | blk_queue_max_phys_segments(q, queue_max_phys_segments(q) - 1); | |
656 | q->dma_drain_needed = dma_drain_needed; | |
657 | q->dma_drain_buffer = buf; | |
658 | q->dma_drain_size = size; | |
659 | ||
660 | return 0; | |
661 | } | |
662 | EXPORT_SYMBOL_GPL(blk_queue_dma_drain); | |
663 | ||
664 | /** | |
665 | * blk_queue_segment_boundary - set boundary rules for segment merging | |
666 | * @q: the request queue for the device | |
667 | * @mask: the memory boundary mask | |
668 | **/ | |
669 | void blk_queue_segment_boundary(struct request_queue *q, unsigned long mask) | |
670 | { | |
671 | if (mask < PAGE_CACHE_SIZE - 1) { | |
672 | mask = PAGE_CACHE_SIZE - 1; | |
673 | printk(KERN_INFO "%s: set to minimum %lx\n", | |
674 | __func__, mask); | |
675 | } | |
676 | ||
677 | q->limits.seg_boundary_mask = mask; | |
678 | } | |
679 | EXPORT_SYMBOL(blk_queue_segment_boundary); | |
680 | ||
681 | /** | |
682 | * blk_queue_dma_alignment - set dma length and memory alignment | |
683 | * @q: the request queue for the device | |
684 | * @mask: alignment mask | |
685 | * | |
686 | * description: | |
687 | * set required memory and length alignment for direct dma transactions. | |
688 | * this is used when building direct io requests for the queue. | |
689 | * | |
690 | **/ | |
691 | void blk_queue_dma_alignment(struct request_queue *q, int mask) | |
692 | { | |
693 | q->dma_alignment = mask; | |
694 | } | |
695 | EXPORT_SYMBOL(blk_queue_dma_alignment); | |
696 | ||
697 | /** | |
698 | * blk_queue_update_dma_alignment - update dma length and memory alignment | |
699 | * @q: the request queue for the device | |
700 | * @mask: alignment mask | |
701 | * | |
702 | * description: | |
703 | * update required memory and length alignment for direct dma transactions. | |
704 | * If the requested alignment is larger than the current alignment, then | |
705 | * the current queue alignment is updated to the new value, otherwise it | |
706 | * is left alone. The design of this is to allow multiple objects | |
707 | * (driver, device, transport etc) to set their respective | |
708 | * alignments without having them interfere. | |
709 | * | |
710 | **/ | |
711 | void blk_queue_update_dma_alignment(struct request_queue *q, int mask) | |
712 | { | |
713 | BUG_ON(mask > PAGE_SIZE); | |
714 | ||
715 | if (mask > q->dma_alignment) | |
716 | q->dma_alignment = mask; | |
717 | } | |
718 | EXPORT_SYMBOL(blk_queue_update_dma_alignment); | |
719 | ||
720 | static int __init blk_settings_init(void) | |
721 | { | |
722 | blk_max_low_pfn = max_low_pfn - 1; | |
723 | blk_max_pfn = max_pfn - 1; | |
724 | return 0; | |
725 | } | |
726 | subsys_initcall(blk_settings_init); |