Commit | Line | Data |
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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 | EXPORT_SYMBOL(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 | } | |
86db1e29 JA |
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 | } | |
86db1e29 JA |
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 | } | |
86db1e29 JA |
62 | EXPORT_SYMBOL(blk_queue_softirq_done); |
63 | ||
64 | /** | |
65 | * blk_queue_make_request - define an alternate make_request function for a device | |
66 | * @q: the request queue for the device to be affected | |
67 | * @mfn: the alternate make_request function | |
68 | * | |
69 | * Description: | |
70 | * The normal way for &struct bios to be passed to a device | |
71 | * driver is for them to be collected into requests on a request | |
72 | * queue, and then to allow the device driver to select requests | |
73 | * off that queue when it is ready. This works well for many block | |
74 | * devices. However some block devices (typically virtual devices | |
75 | * such as md or lvm) do not benefit from the processing on the | |
76 | * request queue, and are served best by having the requests passed | |
77 | * directly to them. This can be achieved by providing a function | |
78 | * to blk_queue_make_request(). | |
79 | * | |
80 | * Caveat: | |
81 | * The driver that does this *must* be able to deal appropriately | |
82 | * with buffers in "highmemory". This can be accomplished by either calling | |
83 | * __bio_kmap_atomic() to get a temporary kernel mapping, or by calling | |
84 | * blk_queue_bounce() to create a buffer in normal memory. | |
85 | **/ | |
6728cb0e | 86 | void blk_queue_make_request(struct request_queue *q, make_request_fn *mfn) |
86db1e29 JA |
87 | { |
88 | /* | |
89 | * set defaults | |
90 | */ | |
91 | q->nr_requests = BLKDEV_MAX_RQ; | |
92 | blk_queue_max_phys_segments(q, MAX_PHYS_SEGMENTS); | |
93 | blk_queue_max_hw_segments(q, MAX_HW_SEGMENTS); | |
94 | q->make_request_fn = mfn; | |
6728cb0e JA |
95 | q->backing_dev_info.ra_pages = |
96 | (VM_MAX_READAHEAD * 1024) / PAGE_CACHE_SIZE; | |
86db1e29 JA |
97 | q->backing_dev_info.state = 0; |
98 | q->backing_dev_info.capabilities = BDI_CAP_MAP_COPY; | |
99 | blk_queue_max_sectors(q, SAFE_MAX_SECTORS); | |
100 | blk_queue_hardsect_size(q, 512); | |
101 | blk_queue_dma_alignment(q, 511); | |
102 | blk_queue_congestion_threshold(q); | |
103 | q->nr_batching = BLK_BATCH_REQ; | |
104 | ||
105 | q->unplug_thresh = 4; /* hmm */ | |
106 | q->unplug_delay = (3 * HZ) / 1000; /* 3 milliseconds */ | |
107 | if (q->unplug_delay == 0) | |
108 | q->unplug_delay = 1; | |
109 | ||
110 | INIT_WORK(&q->unplug_work, blk_unplug_work); | |
111 | ||
112 | q->unplug_timer.function = blk_unplug_timeout; | |
113 | q->unplug_timer.data = (unsigned long)q; | |
114 | ||
115 | /* | |
116 | * by default assume old behaviour and bounce for any highmem page | |
117 | */ | |
118 | blk_queue_bounce_limit(q, BLK_BOUNCE_HIGH); | |
119 | } | |
86db1e29 JA |
120 | EXPORT_SYMBOL(blk_queue_make_request); |
121 | ||
122 | /** | |
123 | * blk_queue_bounce_limit - set bounce buffer limit for queue | |
124 | * @q: the request queue for the device | |
125 | * @dma_addr: bus address limit | |
126 | * | |
127 | * Description: | |
128 | * Different hardware can have different requirements as to what pages | |
129 | * it can do I/O directly to. A low level driver can call | |
130 | * blk_queue_bounce_limit to have lower memory pages allocated as bounce | |
131 | * buffers for doing I/O to pages residing above @page. | |
132 | **/ | |
133 | void blk_queue_bounce_limit(struct request_queue *q, u64 dma_addr) | |
134 | { | |
6728cb0e | 135 | unsigned long b_pfn = dma_addr >> PAGE_SHIFT; |
86db1e29 JA |
136 | int dma = 0; |
137 | ||
138 | q->bounce_gfp = GFP_NOIO; | |
139 | #if BITS_PER_LONG == 64 | |
140 | /* Assume anything <= 4GB can be handled by IOMMU. | |
141 | Actually some IOMMUs can handle everything, but I don't | |
142 | know of a way to test this here. */ | |
419c434c | 143 | if (b_pfn <= (min_t(u64, 0xffffffff, BLK_BOUNCE_HIGH) >> PAGE_SHIFT)) |
86db1e29 JA |
144 | dma = 1; |
145 | q->bounce_pfn = max_low_pfn; | |
146 | #else | |
6728cb0e | 147 | if (b_pfn < blk_max_low_pfn) |
86db1e29 | 148 | dma = 1; |
6728cb0e | 149 | q->bounce_pfn = b_pfn; |
86db1e29 JA |
150 | #endif |
151 | if (dma) { | |
152 | init_emergency_isa_pool(); | |
153 | q->bounce_gfp = GFP_NOIO | GFP_DMA; | |
6728cb0e | 154 | q->bounce_pfn = b_pfn; |
86db1e29 JA |
155 | } |
156 | } | |
86db1e29 JA |
157 | EXPORT_SYMBOL(blk_queue_bounce_limit); |
158 | ||
159 | /** | |
160 | * blk_queue_max_sectors - set max sectors for a request for this queue | |
161 | * @q: the request queue for the device | |
162 | * @max_sectors: max sectors in the usual 512b unit | |
163 | * | |
164 | * Description: | |
165 | * Enables a low level driver to set an upper limit on the size of | |
166 | * received requests. | |
167 | **/ | |
168 | void blk_queue_max_sectors(struct request_queue *q, unsigned int max_sectors) | |
169 | { | |
170 | if ((max_sectors << 9) < PAGE_CACHE_SIZE) { | |
171 | max_sectors = 1 << (PAGE_CACHE_SHIFT - 9); | |
6728cb0e JA |
172 | printk(KERN_INFO "%s: set to minimum %d\n", __FUNCTION__, |
173 | max_sectors); | |
86db1e29 JA |
174 | } |
175 | ||
176 | if (BLK_DEF_MAX_SECTORS > max_sectors) | |
177 | q->max_hw_sectors = q->max_sectors = max_sectors; | |
178 | else { | |
179 | q->max_sectors = BLK_DEF_MAX_SECTORS; | |
180 | q->max_hw_sectors = max_sectors; | |
181 | } | |
182 | } | |
86db1e29 JA |
183 | EXPORT_SYMBOL(blk_queue_max_sectors); |
184 | ||
185 | /** | |
186 | * blk_queue_max_phys_segments - set max phys segments for a request for this queue | |
187 | * @q: the request queue for the device | |
188 | * @max_segments: max number of segments | |
189 | * | |
190 | * Description: | |
191 | * Enables a low level driver to set an upper limit on the number of | |
192 | * physical data segments in a request. This would be the largest sized | |
193 | * scatter list the driver could handle. | |
194 | **/ | |
195 | void blk_queue_max_phys_segments(struct request_queue *q, | |
196 | unsigned short max_segments) | |
197 | { | |
198 | if (!max_segments) { | |
199 | max_segments = 1; | |
6728cb0e JA |
200 | printk(KERN_INFO "%s: set to minimum %d\n", __FUNCTION__, |
201 | max_segments); | |
86db1e29 JA |
202 | } |
203 | ||
204 | q->max_phys_segments = max_segments; | |
205 | } | |
86db1e29 JA |
206 | EXPORT_SYMBOL(blk_queue_max_phys_segments); |
207 | ||
208 | /** | |
209 | * blk_queue_max_hw_segments - set max hw segments for a request for this queue | |
210 | * @q: the request queue for the device | |
211 | * @max_segments: max number of segments | |
212 | * | |
213 | * Description: | |
214 | * Enables a low level driver to set an upper limit on the number of | |
215 | * hw data segments in a request. This would be the largest number of | |
216 | * address/length pairs the host adapter can actually give as once | |
217 | * to the device. | |
218 | **/ | |
219 | void blk_queue_max_hw_segments(struct request_queue *q, | |
220 | unsigned short max_segments) | |
221 | { | |
222 | if (!max_segments) { | |
223 | max_segments = 1; | |
6728cb0e JA |
224 | printk(KERN_INFO "%s: set to minimum %d\n", __FUNCTION__, |
225 | max_segments); | |
86db1e29 JA |
226 | } |
227 | ||
228 | q->max_hw_segments = max_segments; | |
229 | } | |
86db1e29 JA |
230 | EXPORT_SYMBOL(blk_queue_max_hw_segments); |
231 | ||
232 | /** | |
233 | * blk_queue_max_segment_size - set max segment size for blk_rq_map_sg | |
234 | * @q: the request queue for the device | |
235 | * @max_size: max size of segment in bytes | |
236 | * | |
237 | * Description: | |
238 | * Enables a low level driver to set an upper limit on the size of a | |
239 | * coalesced segment | |
240 | **/ | |
241 | void blk_queue_max_segment_size(struct request_queue *q, unsigned int max_size) | |
242 | { | |
243 | if (max_size < PAGE_CACHE_SIZE) { | |
244 | max_size = PAGE_CACHE_SIZE; | |
6728cb0e JA |
245 | printk(KERN_INFO "%s: set to minimum %d\n", __FUNCTION__, |
246 | max_size); | |
86db1e29 JA |
247 | } |
248 | ||
249 | q->max_segment_size = max_size; | |
250 | } | |
86db1e29 JA |
251 | EXPORT_SYMBOL(blk_queue_max_segment_size); |
252 | ||
253 | /** | |
254 | * blk_queue_hardsect_size - set hardware sector size for the queue | |
255 | * @q: the request queue for the device | |
256 | * @size: the hardware sector size, in bytes | |
257 | * | |
258 | * Description: | |
259 | * This should typically be set to the lowest possible sector size | |
260 | * that the hardware can operate on (possible without reverting to | |
261 | * even internal read-modify-write operations). Usually the default | |
262 | * of 512 covers most hardware. | |
263 | **/ | |
264 | void blk_queue_hardsect_size(struct request_queue *q, unsigned short size) | |
265 | { | |
266 | q->hardsect_size = size; | |
267 | } | |
86db1e29 JA |
268 | EXPORT_SYMBOL(blk_queue_hardsect_size); |
269 | ||
270 | /* | |
271 | * Returns the minimum that is _not_ zero, unless both are zero. | |
272 | */ | |
273 | #define min_not_zero(l, r) (l == 0) ? r : ((r == 0) ? l : min(l, r)) | |
274 | ||
275 | /** | |
276 | * blk_queue_stack_limits - inherit underlying queue limits for stacked drivers | |
277 | * @t: the stacking driver (top) | |
278 | * @b: the underlying device (bottom) | |
279 | **/ | |
280 | void blk_queue_stack_limits(struct request_queue *t, struct request_queue *b) | |
281 | { | |
282 | /* zero is "infinity" */ | |
6728cb0e JA |
283 | t->max_sectors = min_not_zero(t->max_sectors, b->max_sectors); |
284 | t->max_hw_sectors = min_not_zero(t->max_hw_sectors, b->max_hw_sectors); | |
86db1e29 | 285 | |
6728cb0e JA |
286 | t->max_phys_segments = min(t->max_phys_segments, b->max_phys_segments); |
287 | t->max_hw_segments = min(t->max_hw_segments, b->max_hw_segments); | |
288 | t->max_segment_size = min(t->max_segment_size, b->max_segment_size); | |
289 | t->hardsect_size = max(t->hardsect_size, b->hardsect_size); | |
86db1e29 JA |
290 | if (!test_bit(QUEUE_FLAG_CLUSTER, &b->queue_flags)) |
291 | clear_bit(QUEUE_FLAG_CLUSTER, &t->queue_flags); | |
292 | } | |
86db1e29 JA |
293 | EXPORT_SYMBOL(blk_queue_stack_limits); |
294 | ||
e3790c7d TH |
295 | /** |
296 | * blk_queue_dma_pad - set pad mask | |
297 | * @q: the request queue for the device | |
298 | * @mask: pad mask | |
299 | * | |
300 | * Set pad mask. Direct IO requests are padded to the mask specified. | |
301 | * | |
302 | * Appending pad buffer to a request modifies ->data_len such that it | |
303 | * includes the pad buffer. The original requested data length can be | |
304 | * obtained using blk_rq_raw_data_len(). | |
305 | **/ | |
306 | void blk_queue_dma_pad(struct request_queue *q, unsigned int mask) | |
307 | { | |
308 | q->dma_pad_mask = mask; | |
309 | } | |
310 | EXPORT_SYMBOL(blk_queue_dma_pad); | |
311 | ||
86db1e29 JA |
312 | /** |
313 | * blk_queue_dma_drain - Set up a drain buffer for excess dma. | |
86db1e29 | 314 | * @q: the request queue for the device |
2fb98e84 | 315 | * @dma_drain_needed: fn which returns non-zero if drain is necessary |
86db1e29 JA |
316 | * @buf: physically contiguous buffer |
317 | * @size: size of the buffer in bytes | |
318 | * | |
319 | * Some devices have excess DMA problems and can't simply discard (or | |
320 | * zero fill) the unwanted piece of the transfer. They have to have a | |
321 | * real area of memory to transfer it into. The use case for this is | |
322 | * ATAPI devices in DMA mode. If the packet command causes a transfer | |
323 | * bigger than the transfer size some HBAs will lock up if there | |
324 | * aren't DMA elements to contain the excess transfer. What this API | |
325 | * does is adjust the queue so that the buf is always appended | |
326 | * silently to the scatterlist. | |
327 | * | |
328 | * Note: This routine adjusts max_hw_segments to make room for | |
329 | * appending the drain buffer. If you call | |
330 | * blk_queue_max_hw_segments() or blk_queue_max_phys_segments() after | |
331 | * calling this routine, you must set the limit to one fewer than your | |
332 | * device can support otherwise there won't be room for the drain | |
333 | * buffer. | |
334 | */ | |
448da4d2 | 335 | int blk_queue_dma_drain(struct request_queue *q, |
2fb98e84 TH |
336 | dma_drain_needed_fn *dma_drain_needed, |
337 | void *buf, unsigned int size) | |
86db1e29 JA |
338 | { |
339 | if (q->max_hw_segments < 2 || q->max_phys_segments < 2) | |
340 | return -EINVAL; | |
341 | /* make room for appending the drain */ | |
342 | --q->max_hw_segments; | |
343 | --q->max_phys_segments; | |
2fb98e84 | 344 | q->dma_drain_needed = dma_drain_needed; |
86db1e29 JA |
345 | q->dma_drain_buffer = buf; |
346 | q->dma_drain_size = size; | |
347 | ||
348 | return 0; | |
349 | } | |
86db1e29 JA |
350 | EXPORT_SYMBOL_GPL(blk_queue_dma_drain); |
351 | ||
352 | /** | |
353 | * blk_queue_segment_boundary - set boundary rules for segment merging | |
354 | * @q: the request queue for the device | |
355 | * @mask: the memory boundary mask | |
356 | **/ | |
357 | void blk_queue_segment_boundary(struct request_queue *q, unsigned long mask) | |
358 | { | |
359 | if (mask < PAGE_CACHE_SIZE - 1) { | |
360 | mask = PAGE_CACHE_SIZE - 1; | |
6728cb0e JA |
361 | printk(KERN_INFO "%s: set to minimum %lx\n", __FUNCTION__, |
362 | mask); | |
86db1e29 JA |
363 | } |
364 | ||
365 | q->seg_boundary_mask = mask; | |
366 | } | |
86db1e29 JA |
367 | EXPORT_SYMBOL(blk_queue_segment_boundary); |
368 | ||
369 | /** | |
370 | * blk_queue_dma_alignment - set dma length and memory alignment | |
371 | * @q: the request queue for the device | |
372 | * @mask: alignment mask | |
373 | * | |
374 | * description: | |
375 | * set required memory and length aligment for direct dma transactions. | |
376 | * this is used when buiding direct io requests for the queue. | |
377 | * | |
378 | **/ | |
379 | void blk_queue_dma_alignment(struct request_queue *q, int mask) | |
380 | { | |
381 | q->dma_alignment = mask; | |
382 | } | |
86db1e29 JA |
383 | EXPORT_SYMBOL(blk_queue_dma_alignment); |
384 | ||
385 | /** | |
386 | * blk_queue_update_dma_alignment - update dma length and memory alignment | |
387 | * @q: the request queue for the device | |
388 | * @mask: alignment mask | |
389 | * | |
390 | * description: | |
391 | * update required memory and length aligment for direct dma transactions. | |
392 | * If the requested alignment is larger than the current alignment, then | |
393 | * the current queue alignment is updated to the new value, otherwise it | |
394 | * is left alone. The design of this is to allow multiple objects | |
395 | * (driver, device, transport etc) to set their respective | |
396 | * alignments without having them interfere. | |
397 | * | |
398 | **/ | |
399 | void blk_queue_update_dma_alignment(struct request_queue *q, int mask) | |
400 | { | |
401 | BUG_ON(mask > PAGE_SIZE); | |
402 | ||
403 | if (mask > q->dma_alignment) | |
404 | q->dma_alignment = mask; | |
405 | } | |
86db1e29 JA |
406 | EXPORT_SYMBOL(blk_queue_update_dma_alignment); |
407 | ||
52ff4cae | 408 | static int __init blk_settings_init(void) |
86db1e29 JA |
409 | { |
410 | blk_max_low_pfn = max_low_pfn - 1; | |
411 | blk_max_pfn = max_pfn - 1; | |
412 | return 0; | |
413 | } | |
414 | subsys_initcall(blk_settings_init); |