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86db1e29 JA |
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 | ||
11 | #include "blk.h" | |
12 | ||
6728cb0e | 13 | unsigned long blk_max_low_pfn; |
86db1e29 | 14 | EXPORT_SYMBOL(blk_max_low_pfn); |
6728cb0e JA |
15 | |
16 | unsigned long blk_max_pfn; | |
86db1e29 JA |
17 | |
18 | /** | |
19 | * blk_queue_prep_rq - set a prepare_request function for queue | |
20 | * @q: queue | |
21 | * @pfn: prepare_request function | |
22 | * | |
23 | * It's possible for a queue to register a prepare_request callback which | |
24 | * is invoked before the request is handed to the request_fn. The goal of | |
25 | * the function is to prepare a request for I/O, it can be used to build a | |
26 | * cdb from the request data for instance. | |
27 | * | |
28 | */ | |
29 | void blk_queue_prep_rq(struct request_queue *q, prep_rq_fn *pfn) | |
30 | { | |
31 | q->prep_rq_fn = pfn; | |
32 | } | |
86db1e29 JA |
33 | EXPORT_SYMBOL(blk_queue_prep_rq); |
34 | ||
fb2dce86 DW |
35 | /** |
36 | * blk_queue_set_discard - set a discard_sectors function for queue | |
37 | * @q: queue | |
38 | * @dfn: prepare_discard function | |
39 | * | |
40 | * It's possible for a queue to register a discard callback which is used | |
41 | * to transform a discard request into the appropriate type for the | |
42 | * hardware. If none is registered, then discard requests are failed | |
43 | * with %EOPNOTSUPP. | |
44 | * | |
45 | */ | |
46 | void blk_queue_set_discard(struct request_queue *q, prepare_discard_fn *dfn) | |
47 | { | |
48 | q->prepare_discard_fn = dfn; | |
49 | } | |
50 | EXPORT_SYMBOL(blk_queue_set_discard); | |
51 | ||
86db1e29 JA |
52 | /** |
53 | * blk_queue_merge_bvec - set a merge_bvec function for queue | |
54 | * @q: queue | |
55 | * @mbfn: merge_bvec_fn | |
56 | * | |
57 | * Usually queues have static limitations on the max sectors or segments that | |
58 | * we can put in a request. Stacking drivers may have some settings that | |
59 | * are dynamic, and thus we have to query the queue whether it is ok to | |
60 | * add a new bio_vec to a bio at a given offset or not. If the block device | |
61 | * has such limitations, it needs to register a merge_bvec_fn to control | |
62 | * the size of bio's sent to it. Note that a block device *must* allow a | |
63 | * single page to be added to an empty bio. The block device driver may want | |
64 | * to use the bio_split() function to deal with these bio's. By default | |
65 | * no merge_bvec_fn is defined for a queue, and only the fixed limits are | |
66 | * honored. | |
67 | */ | |
68 | void blk_queue_merge_bvec(struct request_queue *q, merge_bvec_fn *mbfn) | |
69 | { | |
70 | q->merge_bvec_fn = mbfn; | |
71 | } | |
86db1e29 JA |
72 | EXPORT_SYMBOL(blk_queue_merge_bvec); |
73 | ||
74 | void blk_queue_softirq_done(struct request_queue *q, softirq_done_fn *fn) | |
75 | { | |
76 | q->softirq_done_fn = fn; | |
77 | } | |
86db1e29 JA |
78 | EXPORT_SYMBOL(blk_queue_softirq_done); |
79 | ||
80 | /** | |
81 | * blk_queue_make_request - define an alternate make_request function for a device | |
82 | * @q: the request queue for the device to be affected | |
83 | * @mfn: the alternate make_request function | |
84 | * | |
85 | * Description: | |
86 | * The normal way for &struct bios to be passed to a device | |
87 | * driver is for them to be collected into requests on a request | |
88 | * queue, and then to allow the device driver to select requests | |
89 | * off that queue when it is ready. This works well for many block | |
90 | * devices. However some block devices (typically virtual devices | |
91 | * such as md or lvm) do not benefit from the processing on the | |
92 | * request queue, and are served best by having the requests passed | |
93 | * directly to them. This can be achieved by providing a function | |
94 | * to blk_queue_make_request(). | |
95 | * | |
96 | * Caveat: | |
97 | * The driver that does this *must* be able to deal appropriately | |
98 | * with buffers in "highmemory". This can be accomplished by either calling | |
99 | * __bio_kmap_atomic() to get a temporary kernel mapping, or by calling | |
100 | * blk_queue_bounce() to create a buffer in normal memory. | |
101 | **/ | |
6728cb0e | 102 | void blk_queue_make_request(struct request_queue *q, make_request_fn *mfn) |
86db1e29 JA |
103 | { |
104 | /* | |
105 | * set defaults | |
106 | */ | |
107 | q->nr_requests = BLKDEV_MAX_RQ; | |
108 | blk_queue_max_phys_segments(q, MAX_PHYS_SEGMENTS); | |
109 | blk_queue_max_hw_segments(q, MAX_HW_SEGMENTS); | |
110 | q->make_request_fn = mfn; | |
6728cb0e JA |
111 | q->backing_dev_info.ra_pages = |
112 | (VM_MAX_READAHEAD * 1024) / PAGE_CACHE_SIZE; | |
86db1e29 JA |
113 | q->backing_dev_info.state = 0; |
114 | q->backing_dev_info.capabilities = BDI_CAP_MAP_COPY; | |
115 | blk_queue_max_sectors(q, SAFE_MAX_SECTORS); | |
116 | blk_queue_hardsect_size(q, 512); | |
117 | blk_queue_dma_alignment(q, 511); | |
118 | blk_queue_congestion_threshold(q); | |
119 | q->nr_batching = BLK_BATCH_REQ; | |
120 | ||
121 | q->unplug_thresh = 4; /* hmm */ | |
122 | q->unplug_delay = (3 * HZ) / 1000; /* 3 milliseconds */ | |
123 | if (q->unplug_delay == 0) | |
124 | q->unplug_delay = 1; | |
125 | ||
126 | INIT_WORK(&q->unplug_work, blk_unplug_work); | |
127 | ||
128 | q->unplug_timer.function = blk_unplug_timeout; | |
129 | q->unplug_timer.data = (unsigned long)q; | |
130 | ||
131 | /* | |
132 | * by default assume old behaviour and bounce for any highmem page | |
133 | */ | |
134 | blk_queue_bounce_limit(q, BLK_BOUNCE_HIGH); | |
135 | } | |
86db1e29 JA |
136 | EXPORT_SYMBOL(blk_queue_make_request); |
137 | ||
138 | /** | |
139 | * blk_queue_bounce_limit - set bounce buffer limit for queue | |
140 | * @q: the request queue for the device | |
141 | * @dma_addr: bus address limit | |
142 | * | |
143 | * Description: | |
144 | * Different hardware can have different requirements as to what pages | |
145 | * it can do I/O directly to. A low level driver can call | |
146 | * blk_queue_bounce_limit to have lower memory pages allocated as bounce | |
710027a4 | 147 | * buffers for doing I/O to pages residing above @dma_addr. |
86db1e29 JA |
148 | **/ |
149 | void blk_queue_bounce_limit(struct request_queue *q, u64 dma_addr) | |
150 | { | |
6728cb0e | 151 | unsigned long b_pfn = dma_addr >> PAGE_SHIFT; |
86db1e29 JA |
152 | int dma = 0; |
153 | ||
154 | q->bounce_gfp = GFP_NOIO; | |
155 | #if BITS_PER_LONG == 64 | |
156 | /* Assume anything <= 4GB can be handled by IOMMU. | |
157 | Actually some IOMMUs can handle everything, but I don't | |
158 | know of a way to test this here. */ | |
00d61e3e | 159 | if (b_pfn < (min_t(u64, 0x100000000UL, BLK_BOUNCE_HIGH) >> PAGE_SHIFT)) |
86db1e29 JA |
160 | dma = 1; |
161 | q->bounce_pfn = max_low_pfn; | |
162 | #else | |
6728cb0e | 163 | if (b_pfn < blk_max_low_pfn) |
86db1e29 | 164 | dma = 1; |
6728cb0e | 165 | q->bounce_pfn = b_pfn; |
86db1e29 JA |
166 | #endif |
167 | if (dma) { | |
168 | init_emergency_isa_pool(); | |
169 | q->bounce_gfp = GFP_NOIO | GFP_DMA; | |
6728cb0e | 170 | q->bounce_pfn = b_pfn; |
86db1e29 JA |
171 | } |
172 | } | |
86db1e29 JA |
173 | EXPORT_SYMBOL(blk_queue_bounce_limit); |
174 | ||
175 | /** | |
176 | * blk_queue_max_sectors - set max sectors for a request for this queue | |
177 | * @q: the request queue for the device | |
178 | * @max_sectors: max sectors in the usual 512b unit | |
179 | * | |
180 | * Description: | |
181 | * Enables a low level driver to set an upper limit on the size of | |
182 | * received requests. | |
183 | **/ | |
184 | void blk_queue_max_sectors(struct request_queue *q, unsigned int max_sectors) | |
185 | { | |
186 | if ((max_sectors << 9) < PAGE_CACHE_SIZE) { | |
187 | max_sectors = 1 << (PAGE_CACHE_SHIFT - 9); | |
24c03d47 HH |
188 | printk(KERN_INFO "%s: set to minimum %d\n", |
189 | __func__, max_sectors); | |
86db1e29 JA |
190 | } |
191 | ||
192 | if (BLK_DEF_MAX_SECTORS > max_sectors) | |
193 | q->max_hw_sectors = q->max_sectors = max_sectors; | |
194 | else { | |
195 | q->max_sectors = BLK_DEF_MAX_SECTORS; | |
196 | q->max_hw_sectors = max_sectors; | |
197 | } | |
198 | } | |
86db1e29 JA |
199 | EXPORT_SYMBOL(blk_queue_max_sectors); |
200 | ||
201 | /** | |
202 | * blk_queue_max_phys_segments - set max phys segments for a request for this queue | |
203 | * @q: the request queue for the device | |
204 | * @max_segments: max number of segments | |
205 | * | |
206 | * Description: | |
207 | * Enables a low level driver to set an upper limit on the number of | |
208 | * physical data segments in a request. This would be the largest sized | |
209 | * scatter list the driver could handle. | |
210 | **/ | |
211 | void blk_queue_max_phys_segments(struct request_queue *q, | |
212 | unsigned short max_segments) | |
213 | { | |
214 | if (!max_segments) { | |
215 | max_segments = 1; | |
24c03d47 HH |
216 | printk(KERN_INFO "%s: set to minimum %d\n", |
217 | __func__, max_segments); | |
86db1e29 JA |
218 | } |
219 | ||
220 | q->max_phys_segments = max_segments; | |
221 | } | |
86db1e29 JA |
222 | EXPORT_SYMBOL(blk_queue_max_phys_segments); |
223 | ||
224 | /** | |
225 | * blk_queue_max_hw_segments - set max hw segments for a request for this queue | |
226 | * @q: the request queue for the device | |
227 | * @max_segments: max number of segments | |
228 | * | |
229 | * Description: | |
230 | * Enables a low level driver to set an upper limit on the number of | |
231 | * hw data segments in a request. This would be the largest number of | |
710027a4 | 232 | * address/length pairs the host adapter can actually give at once |
86db1e29 JA |
233 | * to the device. |
234 | **/ | |
235 | void blk_queue_max_hw_segments(struct request_queue *q, | |
236 | unsigned short max_segments) | |
237 | { | |
238 | if (!max_segments) { | |
239 | max_segments = 1; | |
24c03d47 HH |
240 | printk(KERN_INFO "%s: set to minimum %d\n", |
241 | __func__, max_segments); | |
86db1e29 JA |
242 | } |
243 | ||
244 | q->max_hw_segments = max_segments; | |
245 | } | |
86db1e29 JA |
246 | EXPORT_SYMBOL(blk_queue_max_hw_segments); |
247 | ||
248 | /** | |
249 | * blk_queue_max_segment_size - set max segment size for blk_rq_map_sg | |
250 | * @q: the request queue for the device | |
251 | * @max_size: max size of segment in bytes | |
252 | * | |
253 | * Description: | |
254 | * Enables a low level driver to set an upper limit on the size of a | |
255 | * coalesced segment | |
256 | **/ | |
257 | void blk_queue_max_segment_size(struct request_queue *q, unsigned int max_size) | |
258 | { | |
259 | if (max_size < PAGE_CACHE_SIZE) { | |
260 | max_size = PAGE_CACHE_SIZE; | |
24c03d47 HH |
261 | printk(KERN_INFO "%s: set to minimum %d\n", |
262 | __func__, max_size); | |
86db1e29 JA |
263 | } |
264 | ||
265 | q->max_segment_size = max_size; | |
266 | } | |
86db1e29 JA |
267 | EXPORT_SYMBOL(blk_queue_max_segment_size); |
268 | ||
269 | /** | |
270 | * blk_queue_hardsect_size - set hardware sector size for the queue | |
271 | * @q: the request queue for the device | |
272 | * @size: the hardware sector size, in bytes | |
273 | * | |
274 | * Description: | |
275 | * This should typically be set to the lowest possible sector size | |
276 | * that the hardware can operate on (possible without reverting to | |
277 | * even internal read-modify-write operations). Usually the default | |
278 | * of 512 covers most hardware. | |
279 | **/ | |
280 | void blk_queue_hardsect_size(struct request_queue *q, unsigned short size) | |
281 | { | |
282 | q->hardsect_size = size; | |
283 | } | |
86db1e29 JA |
284 | EXPORT_SYMBOL(blk_queue_hardsect_size); |
285 | ||
286 | /* | |
287 | * Returns the minimum that is _not_ zero, unless both are zero. | |
288 | */ | |
289 | #define min_not_zero(l, r) (l == 0) ? r : ((r == 0) ? l : min(l, r)) | |
290 | ||
291 | /** | |
292 | * blk_queue_stack_limits - inherit underlying queue limits for stacked drivers | |
293 | * @t: the stacking driver (top) | |
294 | * @b: the underlying device (bottom) | |
295 | **/ | |
296 | void blk_queue_stack_limits(struct request_queue *t, struct request_queue *b) | |
297 | { | |
298 | /* zero is "infinity" */ | |
6728cb0e JA |
299 | t->max_sectors = min_not_zero(t->max_sectors, b->max_sectors); |
300 | t->max_hw_sectors = min_not_zero(t->max_hw_sectors, b->max_hw_sectors); | |
86db1e29 | 301 | |
6728cb0e JA |
302 | t->max_phys_segments = min(t->max_phys_segments, b->max_phys_segments); |
303 | t->max_hw_segments = min(t->max_hw_segments, b->max_hw_segments); | |
304 | t->max_segment_size = min(t->max_segment_size, b->max_segment_size); | |
305 | t->hardsect_size = max(t->hardsect_size, b->hardsect_size); | |
e7e72bf6 NB |
306 | if (!t->queue_lock) |
307 | WARN_ON_ONCE(1); | |
308 | else if (!test_bit(QUEUE_FLAG_CLUSTER, &b->queue_flags)) { | |
309 | unsigned long flags; | |
310 | spin_lock_irqsave(t->queue_lock, flags); | |
75ad23bc | 311 | queue_flag_clear(QUEUE_FLAG_CLUSTER, t); |
e7e72bf6 NB |
312 | spin_unlock_irqrestore(t->queue_lock, flags); |
313 | } | |
86db1e29 | 314 | } |
86db1e29 JA |
315 | EXPORT_SYMBOL(blk_queue_stack_limits); |
316 | ||
e3790c7d TH |
317 | /** |
318 | * blk_queue_dma_pad - set pad mask | |
319 | * @q: the request queue for the device | |
320 | * @mask: pad mask | |
321 | * | |
27f8221a | 322 | * Set dma pad mask. |
e3790c7d | 323 | * |
27f8221a FT |
324 | * Appending pad buffer to a request modifies the last entry of a |
325 | * scatter list such that it includes the pad buffer. | |
e3790c7d TH |
326 | **/ |
327 | void blk_queue_dma_pad(struct request_queue *q, unsigned int mask) | |
328 | { | |
329 | q->dma_pad_mask = mask; | |
330 | } | |
331 | EXPORT_SYMBOL(blk_queue_dma_pad); | |
332 | ||
27f8221a FT |
333 | /** |
334 | * blk_queue_update_dma_pad - update pad mask | |
335 | * @q: the request queue for the device | |
336 | * @mask: pad mask | |
337 | * | |
338 | * Update dma pad mask. | |
339 | * | |
340 | * Appending pad buffer to a request modifies the last entry of a | |
341 | * scatter list such that it includes the pad buffer. | |
342 | **/ | |
343 | void blk_queue_update_dma_pad(struct request_queue *q, unsigned int mask) | |
344 | { | |
345 | if (mask > q->dma_pad_mask) | |
346 | q->dma_pad_mask = mask; | |
347 | } | |
348 | EXPORT_SYMBOL(blk_queue_update_dma_pad); | |
349 | ||
86db1e29 JA |
350 | /** |
351 | * blk_queue_dma_drain - Set up a drain buffer for excess dma. | |
86db1e29 | 352 | * @q: the request queue for the device |
2fb98e84 | 353 | * @dma_drain_needed: fn which returns non-zero if drain is necessary |
86db1e29 JA |
354 | * @buf: physically contiguous buffer |
355 | * @size: size of the buffer in bytes | |
356 | * | |
357 | * Some devices have excess DMA problems and can't simply discard (or | |
358 | * zero fill) the unwanted piece of the transfer. They have to have a | |
359 | * real area of memory to transfer it into. The use case for this is | |
360 | * ATAPI devices in DMA mode. If the packet command causes a transfer | |
361 | * bigger than the transfer size some HBAs will lock up if there | |
362 | * aren't DMA elements to contain the excess transfer. What this API | |
363 | * does is adjust the queue so that the buf is always appended | |
364 | * silently to the scatterlist. | |
365 | * | |
366 | * Note: This routine adjusts max_hw_segments to make room for | |
367 | * appending the drain buffer. If you call | |
368 | * blk_queue_max_hw_segments() or blk_queue_max_phys_segments() after | |
369 | * calling this routine, you must set the limit to one fewer than your | |
370 | * device can support otherwise there won't be room for the drain | |
371 | * buffer. | |
372 | */ | |
448da4d2 | 373 | int blk_queue_dma_drain(struct request_queue *q, |
2fb98e84 TH |
374 | dma_drain_needed_fn *dma_drain_needed, |
375 | void *buf, unsigned int size) | |
86db1e29 JA |
376 | { |
377 | if (q->max_hw_segments < 2 || q->max_phys_segments < 2) | |
378 | return -EINVAL; | |
379 | /* make room for appending the drain */ | |
380 | --q->max_hw_segments; | |
381 | --q->max_phys_segments; | |
2fb98e84 | 382 | q->dma_drain_needed = dma_drain_needed; |
86db1e29 JA |
383 | q->dma_drain_buffer = buf; |
384 | q->dma_drain_size = size; | |
385 | ||
386 | return 0; | |
387 | } | |
86db1e29 JA |
388 | EXPORT_SYMBOL_GPL(blk_queue_dma_drain); |
389 | ||
390 | /** | |
391 | * blk_queue_segment_boundary - set boundary rules for segment merging | |
392 | * @q: the request queue for the device | |
393 | * @mask: the memory boundary mask | |
394 | **/ | |
395 | void blk_queue_segment_boundary(struct request_queue *q, unsigned long mask) | |
396 | { | |
397 | if (mask < PAGE_CACHE_SIZE - 1) { | |
398 | mask = PAGE_CACHE_SIZE - 1; | |
24c03d47 HH |
399 | printk(KERN_INFO "%s: set to minimum %lx\n", |
400 | __func__, mask); | |
86db1e29 JA |
401 | } |
402 | ||
403 | q->seg_boundary_mask = mask; | |
404 | } | |
86db1e29 JA |
405 | EXPORT_SYMBOL(blk_queue_segment_boundary); |
406 | ||
407 | /** | |
408 | * blk_queue_dma_alignment - set dma length and memory alignment | |
409 | * @q: the request queue for the device | |
410 | * @mask: alignment mask | |
411 | * | |
412 | * description: | |
710027a4 | 413 | * set required memory and length alignment for direct dma transactions. |
86db1e29 JA |
414 | * this is used when buiding direct io requests for the queue. |
415 | * | |
416 | **/ | |
417 | void blk_queue_dma_alignment(struct request_queue *q, int mask) | |
418 | { | |
419 | q->dma_alignment = mask; | |
420 | } | |
86db1e29 JA |
421 | EXPORT_SYMBOL(blk_queue_dma_alignment); |
422 | ||
423 | /** | |
424 | * blk_queue_update_dma_alignment - update dma length and memory alignment | |
425 | * @q: the request queue for the device | |
426 | * @mask: alignment mask | |
427 | * | |
428 | * description: | |
710027a4 | 429 | * update required memory and length alignment for direct dma transactions. |
86db1e29 JA |
430 | * If the requested alignment is larger than the current alignment, then |
431 | * the current queue alignment is updated to the new value, otherwise it | |
432 | * is left alone. The design of this is to allow multiple objects | |
433 | * (driver, device, transport etc) to set their respective | |
434 | * alignments without having them interfere. | |
435 | * | |
436 | **/ | |
437 | void blk_queue_update_dma_alignment(struct request_queue *q, int mask) | |
438 | { | |
439 | BUG_ON(mask > PAGE_SIZE); | |
440 | ||
441 | if (mask > q->dma_alignment) | |
442 | q->dma_alignment = mask; | |
443 | } | |
86db1e29 JA |
444 | EXPORT_SYMBOL(blk_queue_update_dma_alignment); |
445 | ||
c7c22e4d | 446 | int __init blk_settings_init(void) |
86db1e29 JA |
447 | { |
448 | blk_max_low_pfn = max_low_pfn - 1; | |
449 | blk_max_pfn = max_pfn - 1; | |
450 | return 0; | |
451 | } | |
452 | subsys_initcall(blk_settings_init); |