blob: 57af728d94bb08732e9d217a94dafe9bae9ef992 [file] [log] [blame]
Jens Axboe86db1e22008-01-29 14:53:40 +01001/*
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
Jens Axboe6728cb02008-01-31 13:03:55 +010013unsigned long blk_max_low_pfn;
Jens Axboe86db1e22008-01-29 14:53:40 +010014EXPORT_SYMBOL(blk_max_low_pfn);
Jens Axboe6728cb02008-01-31 13:03:55 +010015
16unsigned long blk_max_pfn;
Jens Axboe86db1e22008-01-29 14:53:40 +010017
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 */
29void blk_queue_prep_rq(struct request_queue *q, prep_rq_fn *pfn)
30{
31 q->prep_rq_fn = pfn;
32}
Jens Axboe86db1e22008-01-29 14:53:40 +010033EXPORT_SYMBOL(blk_queue_prep_rq);
34
35/**
David Woodhousefb2dce82008-08-05 18:01:53 +010036 * 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 */
46void blk_queue_set_discard(struct request_queue *q, prepare_discard_fn *dfn)
47{
48 q->prepare_discard_fn = dfn;
49}
50EXPORT_SYMBOL(blk_queue_set_discard);
51
52/**
Jens Axboe86db1e22008-01-29 14:53:40 +010053 * 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 */
68void blk_queue_merge_bvec(struct request_queue *q, merge_bvec_fn *mbfn)
69{
70 q->merge_bvec_fn = mbfn;
71}
Jens Axboe86db1e22008-01-29 14:53:40 +010072EXPORT_SYMBOL(blk_queue_merge_bvec);
73
74void blk_queue_softirq_done(struct request_queue *q, softirq_done_fn *fn)
75{
76 q->softirq_done_fn = fn;
77}
Jens Axboe86db1e22008-01-29 14:53:40 +010078EXPORT_SYMBOL(blk_queue_softirq_done);
79
Jens Axboe242f9dc2008-09-14 05:55:09 -070080void blk_queue_rq_timeout(struct request_queue *q, unsigned int timeout)
81{
82 q->rq_timeout = timeout;
83}
84EXPORT_SYMBOL_GPL(blk_queue_rq_timeout);
85
86void blk_queue_rq_timed_out(struct request_queue *q, rq_timed_out_fn *fn)
87{
88 q->rq_timed_out_fn = fn;
89}
90EXPORT_SYMBOL_GPL(blk_queue_rq_timed_out);
91
Kiyoshi Uedaef9e3fa2008-10-01 16:12:15 +020092void blk_queue_lld_busy(struct request_queue *q, lld_busy_fn *fn)
93{
94 q->lld_busy_fn = fn;
95}
96EXPORT_SYMBOL_GPL(blk_queue_lld_busy);
97
Jens Axboe86db1e22008-01-29 14:53:40 +010098/**
99 * blk_queue_make_request - define an alternate make_request function for a device
100 * @q: the request queue for the device to be affected
101 * @mfn: the alternate make_request function
102 *
103 * Description:
104 * The normal way for &struct bios to be passed to a device
105 * driver is for them to be collected into requests on a request
106 * queue, and then to allow the device driver to select requests
107 * off that queue when it is ready. This works well for many block
108 * devices. However some block devices (typically virtual devices
109 * such as md or lvm) do not benefit from the processing on the
110 * request queue, and are served best by having the requests passed
111 * directly to them. This can be achieved by providing a function
112 * to blk_queue_make_request().
113 *
114 * Caveat:
115 * The driver that does this *must* be able to deal appropriately
116 * with buffers in "highmemory". This can be accomplished by either calling
117 * __bio_kmap_atomic() to get a temporary kernel mapping, or by calling
118 * blk_queue_bounce() to create a buffer in normal memory.
119 **/
Jens Axboe6728cb02008-01-31 13:03:55 +0100120void blk_queue_make_request(struct request_queue *q, make_request_fn *mfn)
Jens Axboe86db1e22008-01-29 14:53:40 +0100121{
122 /*
123 * set defaults
124 */
125 q->nr_requests = BLKDEV_MAX_RQ;
126 blk_queue_max_phys_segments(q, MAX_PHYS_SEGMENTS);
127 blk_queue_max_hw_segments(q, MAX_HW_SEGMENTS);
Milan Broz0e435ac2008-12-03 12:55:08 +0100128 blk_queue_segment_boundary(q, BLK_SEG_BOUNDARY_MASK);
129 blk_queue_max_segment_size(q, MAX_SEGMENT_SIZE);
130
Jens Axboe86db1e22008-01-29 14:53:40 +0100131 q->make_request_fn = mfn;
Jens Axboe6728cb02008-01-31 13:03:55 +0100132 q->backing_dev_info.ra_pages =
133 (VM_MAX_READAHEAD * 1024) / PAGE_CACHE_SIZE;
Jens Axboe86db1e22008-01-29 14:53:40 +0100134 q->backing_dev_info.state = 0;
135 q->backing_dev_info.capabilities = BDI_CAP_MAP_COPY;
136 blk_queue_max_sectors(q, SAFE_MAX_SECTORS);
137 blk_queue_hardsect_size(q, 512);
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
Jens Axboe86db1e22008-01-29 14:53:40 +0100147 q->unplug_timer.function = blk_unplug_timeout;
148 q->unplug_timer.data = (unsigned long)q;
149
150 /*
151 * by default assume old behaviour and bounce for any highmem page
152 */
153 blk_queue_bounce_limit(q, BLK_BOUNCE_HIGH);
154}
Jens Axboe86db1e22008-01-29 14:53:40 +0100155EXPORT_SYMBOL(blk_queue_make_request);
156
157/**
158 * blk_queue_bounce_limit - set bounce buffer limit for queue
Tejun Heocd0aca2d2009-04-15 22:10:25 +0900159 * @q: the request queue for the device
160 * @dma_mask: the maximum address the device can handle
Jens Axboe86db1e22008-01-29 14:53:40 +0100161 *
162 * Description:
163 * Different hardware can have different requirements as to what pages
164 * it can do I/O directly to. A low level driver can call
165 * blk_queue_bounce_limit to have lower memory pages allocated as bounce
Tejun Heocd0aca2d2009-04-15 22:10:25 +0900166 * buffers for doing I/O to pages residing above @dma_mask.
Jens Axboe86db1e22008-01-29 14:53:40 +0100167 **/
Tejun Heocd0aca2d2009-04-15 22:10:25 +0900168void blk_queue_bounce_limit(struct request_queue *q, u64 dma_mask)
Jens Axboe86db1e22008-01-29 14:53:40 +0100169{
Tejun Heocd0aca2d2009-04-15 22:10:25 +0900170 unsigned long b_pfn = dma_mask >> PAGE_SHIFT;
Jens Axboe86db1e22008-01-29 14:53:40 +0100171 int dma = 0;
172
173 q->bounce_gfp = GFP_NOIO;
174#if BITS_PER_LONG == 64
Tejun Heocd0aca2d2009-04-15 22:10:25 +0900175 /*
176 * Assume anything <= 4GB can be handled by IOMMU. Actually
177 * some IOMMUs can handle everything, but I don't know of a
178 * way to test this here.
179 */
180 if (b_pfn < (min_t(u64, 0xffffffffUL, BLK_BOUNCE_HIGH) >> PAGE_SHIFT))
Jens Axboe86db1e22008-01-29 14:53:40 +0100181 dma = 1;
182 q->bounce_pfn = max_low_pfn;
183#else
Jens Axboe6728cb02008-01-31 13:03:55 +0100184 if (b_pfn < blk_max_low_pfn)
Jens Axboe86db1e22008-01-29 14:53:40 +0100185 dma = 1;
Jens Axboe6728cb02008-01-31 13:03:55 +0100186 q->bounce_pfn = b_pfn;
Jens Axboe86db1e22008-01-29 14:53:40 +0100187#endif
188 if (dma) {
189 init_emergency_isa_pool();
190 q->bounce_gfp = GFP_NOIO | GFP_DMA;
Jens Axboe6728cb02008-01-31 13:03:55 +0100191 q->bounce_pfn = b_pfn;
Jens Axboe86db1e22008-01-29 14:53:40 +0100192 }
193}
Jens Axboe86db1e22008-01-29 14:53:40 +0100194EXPORT_SYMBOL(blk_queue_bounce_limit);
195
196/**
197 * blk_queue_max_sectors - set max sectors for a request for this queue
198 * @q: the request queue for the device
199 * @max_sectors: max sectors in the usual 512b unit
200 *
201 * Description:
202 * Enables a low level driver to set an upper limit on the size of
203 * received requests.
204 **/
205void blk_queue_max_sectors(struct request_queue *q, unsigned int max_sectors)
206{
207 if ((max_sectors << 9) < PAGE_CACHE_SIZE) {
208 max_sectors = 1 << (PAGE_CACHE_SHIFT - 9);
Harvey Harrison24c03d42008-05-01 04:35:17 -0700209 printk(KERN_INFO "%s: set to minimum %d\n",
210 __func__, max_sectors);
Jens Axboe86db1e22008-01-29 14:53:40 +0100211 }
212
213 if (BLK_DEF_MAX_SECTORS > max_sectors)
214 q->max_hw_sectors = q->max_sectors = max_sectors;
215 else {
216 q->max_sectors = BLK_DEF_MAX_SECTORS;
217 q->max_hw_sectors = max_sectors;
218 }
219}
Jens Axboe86db1e22008-01-29 14:53:40 +0100220EXPORT_SYMBOL(blk_queue_max_sectors);
221
222/**
223 * blk_queue_max_phys_segments - set max phys segments for a request for this queue
224 * @q: the request queue for the device
225 * @max_segments: max number of segments
226 *
227 * Description:
228 * Enables a low level driver to set an upper limit on the number of
229 * physical data segments in a request. This would be the largest sized
230 * scatter list the driver could handle.
231 **/
232void blk_queue_max_phys_segments(struct request_queue *q,
233 unsigned short max_segments)
234{
235 if (!max_segments) {
236 max_segments = 1;
Harvey Harrison24c03d42008-05-01 04:35:17 -0700237 printk(KERN_INFO "%s: set to minimum %d\n",
238 __func__, max_segments);
Jens Axboe86db1e22008-01-29 14:53:40 +0100239 }
240
241 q->max_phys_segments = max_segments;
242}
Jens Axboe86db1e22008-01-29 14:53:40 +0100243EXPORT_SYMBOL(blk_queue_max_phys_segments);
244
245/**
246 * blk_queue_max_hw_segments - set max hw segments for a request for this queue
247 * @q: the request queue for the device
248 * @max_segments: max number of segments
249 *
250 * Description:
251 * Enables a low level driver to set an upper limit on the number of
252 * hw data segments in a request. This would be the largest number of
Randy Dunlap710027a2008-08-19 20:13:11 +0200253 * address/length pairs the host adapter can actually give at once
Jens Axboe86db1e22008-01-29 14:53:40 +0100254 * to the device.
255 **/
256void blk_queue_max_hw_segments(struct request_queue *q,
257 unsigned short max_segments)
258{
259 if (!max_segments) {
260 max_segments = 1;
Harvey Harrison24c03d42008-05-01 04:35:17 -0700261 printk(KERN_INFO "%s: set to minimum %d\n",
262 __func__, max_segments);
Jens Axboe86db1e22008-01-29 14:53:40 +0100263 }
264
265 q->max_hw_segments = max_segments;
266}
Jens Axboe86db1e22008-01-29 14:53:40 +0100267EXPORT_SYMBOL(blk_queue_max_hw_segments);
268
269/**
270 * blk_queue_max_segment_size - set max segment size for blk_rq_map_sg
271 * @q: the request queue for the device
272 * @max_size: max size of segment in bytes
273 *
274 * Description:
275 * Enables a low level driver to set an upper limit on the size of a
276 * coalesced segment
277 **/
278void blk_queue_max_segment_size(struct request_queue *q, unsigned int max_size)
279{
280 if (max_size < PAGE_CACHE_SIZE) {
281 max_size = PAGE_CACHE_SIZE;
Harvey Harrison24c03d42008-05-01 04:35:17 -0700282 printk(KERN_INFO "%s: set to minimum %d\n",
283 __func__, max_size);
Jens Axboe86db1e22008-01-29 14:53:40 +0100284 }
285
286 q->max_segment_size = max_size;
287}
Jens Axboe86db1e22008-01-29 14:53:40 +0100288EXPORT_SYMBOL(blk_queue_max_segment_size);
289
290/**
291 * blk_queue_hardsect_size - set hardware sector size for the queue
292 * @q: the request queue for the device
293 * @size: the hardware sector size, in bytes
294 *
295 * Description:
296 * This should typically be set to the lowest possible sector size
297 * that the hardware can operate on (possible without reverting to
298 * even internal read-modify-write operations). Usually the default
299 * of 512 covers most hardware.
300 **/
301void blk_queue_hardsect_size(struct request_queue *q, unsigned short size)
302{
303 q->hardsect_size = size;
304}
Jens Axboe86db1e22008-01-29 14:53:40 +0100305EXPORT_SYMBOL(blk_queue_hardsect_size);
306
307/*
308 * Returns the minimum that is _not_ zero, unless both are zero.
309 */
310#define min_not_zero(l, r) (l == 0) ? r : ((r == 0) ? l : min(l, r))
311
312/**
313 * blk_queue_stack_limits - inherit underlying queue limits for stacked drivers
314 * @t: the stacking driver (top)
315 * @b: the underlying device (bottom)
316 **/
317void blk_queue_stack_limits(struct request_queue *t, struct request_queue *b)
318{
319 /* zero is "infinity" */
Jens Axboe6728cb02008-01-31 13:03:55 +0100320 t->max_sectors = min_not_zero(t->max_sectors, b->max_sectors);
321 t->max_hw_sectors = min_not_zero(t->max_hw_sectors, b->max_hw_sectors);
Milan Broz0e435ac2008-12-03 12:55:08 +0100322 t->seg_boundary_mask = min_not_zero(t->seg_boundary_mask, b->seg_boundary_mask);
Jens Axboe86db1e22008-01-29 14:53:40 +0100323
FUJITA Tomonori18af8b22008-12-04 08:56:35 +0100324 t->max_phys_segments = min_not_zero(t->max_phys_segments, b->max_phys_segments);
325 t->max_hw_segments = min_not_zero(t->max_hw_segments, b->max_hw_segments);
326 t->max_segment_size = min_not_zero(t->max_segment_size, b->max_segment_size);
Jens Axboe6728cb02008-01-31 13:03:55 +0100327 t->hardsect_size = max(t->hardsect_size, b->hardsect_size);
Neil Browne7e72bf2008-05-14 16:05:54 -0700328 if (!t->queue_lock)
329 WARN_ON_ONCE(1);
330 else if (!test_bit(QUEUE_FLAG_CLUSTER, &b->queue_flags)) {
331 unsigned long flags;
332 spin_lock_irqsave(t->queue_lock, flags);
Nick Piggin75ad23b2008-04-29 14:48:33 +0200333 queue_flag_clear(QUEUE_FLAG_CLUSTER, t);
Neil Browne7e72bf2008-05-14 16:05:54 -0700334 spin_unlock_irqrestore(t->queue_lock, flags);
335 }
Jens Axboe86db1e22008-01-29 14:53:40 +0100336}
Jens Axboe86db1e22008-01-29 14:53:40 +0100337EXPORT_SYMBOL(blk_queue_stack_limits);
338
339/**
Tejun Heoe3790c72008-03-04 11:18:17 +0100340 * blk_queue_dma_pad - set pad mask
341 * @q: the request queue for the device
342 * @mask: pad mask
343 *
FUJITA Tomonori27f82212008-07-04 09:30:03 +0200344 * Set dma pad mask.
Tejun Heoe3790c72008-03-04 11:18:17 +0100345 *
FUJITA Tomonori27f82212008-07-04 09:30:03 +0200346 * Appending pad buffer to a request modifies the last entry of a
347 * scatter list such that it includes the pad buffer.
Tejun Heoe3790c72008-03-04 11:18:17 +0100348 **/
349void blk_queue_dma_pad(struct request_queue *q, unsigned int mask)
350{
351 q->dma_pad_mask = mask;
352}
353EXPORT_SYMBOL(blk_queue_dma_pad);
354
355/**
FUJITA Tomonori27f82212008-07-04 09:30:03 +0200356 * blk_queue_update_dma_pad - update pad mask
357 * @q: the request queue for the device
358 * @mask: pad mask
359 *
360 * Update dma pad mask.
361 *
362 * Appending pad buffer to a request modifies the last entry of a
363 * scatter list such that it includes the pad buffer.
364 **/
365void blk_queue_update_dma_pad(struct request_queue *q, unsigned int mask)
366{
367 if (mask > q->dma_pad_mask)
368 q->dma_pad_mask = mask;
369}
370EXPORT_SYMBOL(blk_queue_update_dma_pad);
371
372/**
Jens Axboe86db1e22008-01-29 14:53:40 +0100373 * blk_queue_dma_drain - Set up a drain buffer for excess dma.
Jens Axboe86db1e22008-01-29 14:53:40 +0100374 * @q: the request queue for the device
Tejun Heo2fb98e82008-02-19 11:36:53 +0100375 * @dma_drain_needed: fn which returns non-zero if drain is necessary
Jens Axboe86db1e22008-01-29 14:53:40 +0100376 * @buf: physically contiguous buffer
377 * @size: size of the buffer in bytes
378 *
379 * Some devices have excess DMA problems and can't simply discard (or
380 * zero fill) the unwanted piece of the transfer. They have to have a
381 * real area of memory to transfer it into. The use case for this is
382 * ATAPI devices in DMA mode. If the packet command causes a transfer
383 * bigger than the transfer size some HBAs will lock up if there
384 * aren't DMA elements to contain the excess transfer. What this API
385 * does is adjust the queue so that the buf is always appended
386 * silently to the scatterlist.
387 *
388 * Note: This routine adjusts max_hw_segments to make room for
389 * appending the drain buffer. If you call
390 * blk_queue_max_hw_segments() or blk_queue_max_phys_segments() after
391 * calling this routine, you must set the limit to one fewer than your
392 * device can support otherwise there won't be room for the drain
393 * buffer.
394 */
Harvey Harrison448da4d2008-03-04 11:30:18 +0100395int blk_queue_dma_drain(struct request_queue *q,
Tejun Heo2fb98e82008-02-19 11:36:53 +0100396 dma_drain_needed_fn *dma_drain_needed,
397 void *buf, unsigned int size)
Jens Axboe86db1e22008-01-29 14:53:40 +0100398{
399 if (q->max_hw_segments < 2 || q->max_phys_segments < 2)
400 return -EINVAL;
401 /* make room for appending the drain */
402 --q->max_hw_segments;
403 --q->max_phys_segments;
Tejun Heo2fb98e82008-02-19 11:36:53 +0100404 q->dma_drain_needed = dma_drain_needed;
Jens Axboe86db1e22008-01-29 14:53:40 +0100405 q->dma_drain_buffer = buf;
406 q->dma_drain_size = size;
407
408 return 0;
409}
Jens Axboe86db1e22008-01-29 14:53:40 +0100410EXPORT_SYMBOL_GPL(blk_queue_dma_drain);
411
412/**
413 * blk_queue_segment_boundary - set boundary rules for segment merging
414 * @q: the request queue for the device
415 * @mask: the memory boundary mask
416 **/
417void blk_queue_segment_boundary(struct request_queue *q, unsigned long mask)
418{
419 if (mask < PAGE_CACHE_SIZE - 1) {
420 mask = PAGE_CACHE_SIZE - 1;
Harvey Harrison24c03d42008-05-01 04:35:17 -0700421 printk(KERN_INFO "%s: set to minimum %lx\n",
422 __func__, mask);
Jens Axboe86db1e22008-01-29 14:53:40 +0100423 }
424
425 q->seg_boundary_mask = mask;
426}
Jens Axboe86db1e22008-01-29 14:53:40 +0100427EXPORT_SYMBOL(blk_queue_segment_boundary);
428
429/**
430 * blk_queue_dma_alignment - set dma length and memory alignment
431 * @q: the request queue for the device
432 * @mask: alignment mask
433 *
434 * description:
Randy Dunlap710027a2008-08-19 20:13:11 +0200435 * set required memory and length alignment for direct dma transactions.
Alan Cox8feb4d22009-04-01 15:01:39 +0100436 * this is used when building direct io requests for the queue.
Jens Axboe86db1e22008-01-29 14:53:40 +0100437 *
438 **/
439void blk_queue_dma_alignment(struct request_queue *q, int mask)
440{
441 q->dma_alignment = mask;
442}
Jens Axboe86db1e22008-01-29 14:53:40 +0100443EXPORT_SYMBOL(blk_queue_dma_alignment);
444
445/**
446 * blk_queue_update_dma_alignment - update dma length and memory alignment
447 * @q: the request queue for the device
448 * @mask: alignment mask
449 *
450 * description:
Randy Dunlap710027a2008-08-19 20:13:11 +0200451 * update required memory and length alignment for direct dma transactions.
Jens Axboe86db1e22008-01-29 14:53:40 +0100452 * If the requested alignment is larger than the current alignment, then
453 * the current queue alignment is updated to the new value, otherwise it
454 * is left alone. The design of this is to allow multiple objects
455 * (driver, device, transport etc) to set their respective
456 * alignments without having them interfere.
457 *
458 **/
459void blk_queue_update_dma_alignment(struct request_queue *q, int mask)
460{
461 BUG_ON(mask > PAGE_SIZE);
462
463 if (mask > q->dma_alignment)
464 q->dma_alignment = mask;
465}
Jens Axboe86db1e22008-01-29 14:53:40 +0100466EXPORT_SYMBOL(blk_queue_update_dma_alignment);
467
Harvey Harrisonaeb3d3a2008-08-28 09:27:42 +0200468static int __init blk_settings_init(void)
Jens Axboe86db1e22008-01-29 14:53:40 +0100469{
470 blk_max_low_pfn = max_low_pfn - 1;
471 blk_max_pfn = max_pfn - 1;
472 return 0;
473}
474subsys_initcall(blk_settings_init);