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authorJens Axboe <jens.axboe@oracle.com>2008-01-29 08:53:40 -0500
committerJens Axboe <jens.axboe@oracle.com>2008-01-29 15:55:08 -0500
commit86db1e29772372155db08ff48a9ceb76e11a2ad1 (patch)
tree312f38eb3245873c476c50f816b85610fef9615a /block/blk-settings.c
parent8324aa91d1e11a1fc25f209687a0b2e6c2ed47d0 (diff)
block: continue ll_rw_blk.c splitup
Adds files for barrier handling, rq execution, io context handling, mapping data to requests, and queue settings. Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
Diffstat (limited to 'block/blk-settings.c')
-rw-r--r--block/blk-settings.c402
1 files changed, 402 insertions, 0 deletions
diff --git a/block/blk-settings.c b/block/blk-settings.c
new file mode 100644
index 000000000000..4df09a1b8f43
--- /dev/null
+++ b/block/blk-settings.c
@@ -0,0 +1,402 @@
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
13unsigned long blk_max_low_pfn, blk_max_pfn;
14EXPORT_SYMBOL(blk_max_low_pfn);
15EXPORT_SYMBOL(blk_max_pfn);
16
17/**
18 * blk_queue_prep_rq - set a prepare_request function for queue
19 * @q: queue
20 * @pfn: prepare_request function
21 *
22 * It's possible for a queue to register a prepare_request callback which
23 * is invoked before the request is handed to the request_fn. The goal of
24 * the function is to prepare a request for I/O, it can be used to build a
25 * cdb from the request data for instance.
26 *
27 */
28void blk_queue_prep_rq(struct request_queue *q, prep_rq_fn *pfn)
29{
30 q->prep_rq_fn = pfn;
31}
32
33EXPORT_SYMBOL(blk_queue_prep_rq);
34
35/**
36 * blk_queue_merge_bvec - set a merge_bvec function for queue
37 * @q: queue
38 * @mbfn: merge_bvec_fn
39 *
40 * Usually queues have static limitations on the max sectors or segments that
41 * we can put in a request. Stacking drivers may have some settings that
42 * are dynamic, and thus we have to query the queue whether it is ok to
43 * add a new bio_vec to a bio at a given offset or not. If the block device
44 * has such limitations, it needs to register a merge_bvec_fn to control
45 * the size of bio's sent to it. Note that a block device *must* allow a
46 * single page to be added to an empty bio. The block device driver may want
47 * to use the bio_split() function to deal with these bio's. By default
48 * no merge_bvec_fn is defined for a queue, and only the fixed limits are
49 * honored.
50 */
51void blk_queue_merge_bvec(struct request_queue *q, merge_bvec_fn *mbfn)
52{
53 q->merge_bvec_fn = mbfn;
54}
55
56EXPORT_SYMBOL(blk_queue_merge_bvec);
57
58void blk_queue_softirq_done(struct request_queue *q, softirq_done_fn *fn)
59{
60 q->softirq_done_fn = fn;
61}
62
63EXPORT_SYMBOL(blk_queue_softirq_done);
64
65/**
66 * blk_queue_make_request - define an alternate make_request function for a device
67 * @q: the request queue for the device to be affected
68 * @mfn: the alternate make_request function
69 *
70 * Description:
71 * The normal way for &struct bios to be passed to a device
72 * driver is for them to be collected into requests on a request
73 * queue, and then to allow the device driver to select requests
74 * off that queue when it is ready. This works well for many block
75 * devices. However some block devices (typically virtual devices
76 * such as md or lvm) do not benefit from the processing on the
77 * request queue, and are served best by having the requests passed
78 * directly to them. This can be achieved by providing a function
79 * to blk_queue_make_request().
80 *
81 * Caveat:
82 * The driver that does this *must* be able to deal appropriately
83 * with buffers in "highmemory". This can be accomplished by either calling
84 * __bio_kmap_atomic() to get a temporary kernel mapping, or by calling
85 * blk_queue_bounce() to create a buffer in normal memory.
86 **/
87void blk_queue_make_request(struct request_queue * q, make_request_fn * mfn)
88{
89 /*
90 * set defaults
91 */
92 q->nr_requests = BLKDEV_MAX_RQ;
93 blk_queue_max_phys_segments(q, MAX_PHYS_SEGMENTS);
94 blk_queue_max_hw_segments(q, MAX_HW_SEGMENTS);
95 q->make_request_fn = mfn;
96 q->backing_dev_info.ra_pages = (VM_MAX_READAHEAD * 1024) / PAGE_CACHE_SIZE;
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}
120
121EXPORT_SYMBOL(blk_queue_make_request);
122
123/**
124 * blk_queue_bounce_limit - set bounce buffer limit for queue
125 * @q: the request queue for the device
126 * @dma_addr: bus address limit
127 *
128 * Description:
129 * Different hardware can have different requirements as to what pages
130 * it can do I/O directly to. A low level driver can call
131 * blk_queue_bounce_limit to have lower memory pages allocated as bounce
132 * buffers for doing I/O to pages residing above @page.
133 **/
134void blk_queue_bounce_limit(struct request_queue *q, u64 dma_addr)
135{
136 unsigned long bounce_pfn = dma_addr >> PAGE_SHIFT;
137 int dma = 0;
138
139 q->bounce_gfp = GFP_NOIO;
140#if BITS_PER_LONG == 64
141 /* Assume anything <= 4GB can be handled by IOMMU.
142 Actually some IOMMUs can handle everything, but I don't
143 know of a way to test this here. */
144 if (bounce_pfn < (min_t(u64,0xffffffff,BLK_BOUNCE_HIGH) >> PAGE_SHIFT))
145 dma = 1;
146 q->bounce_pfn = max_low_pfn;
147#else
148 if (bounce_pfn < blk_max_low_pfn)
149 dma = 1;
150 q->bounce_pfn = bounce_pfn;
151#endif
152 if (dma) {
153 init_emergency_isa_pool();
154 q->bounce_gfp = GFP_NOIO | GFP_DMA;
155 q->bounce_pfn = bounce_pfn;
156 }
157}
158
159EXPORT_SYMBOL(blk_queue_bounce_limit);
160
161/**
162 * blk_queue_max_sectors - set max sectors for a request for this queue
163 * @q: the request queue for the device
164 * @max_sectors: max sectors in the usual 512b unit
165 *
166 * Description:
167 * Enables a low level driver to set an upper limit on the size of
168 * received requests.
169 **/
170void blk_queue_max_sectors(struct request_queue *q, unsigned int max_sectors)
171{
172 if ((max_sectors << 9) < PAGE_CACHE_SIZE) {
173 max_sectors = 1 << (PAGE_CACHE_SHIFT - 9);
174 printk("%s: set to minimum %d\n", __FUNCTION__, max_sectors);
175 }
176
177 if (BLK_DEF_MAX_SECTORS > max_sectors)
178 q->max_hw_sectors = q->max_sectors = max_sectors;
179 else {
180 q->max_sectors = BLK_DEF_MAX_SECTORS;
181 q->max_hw_sectors = max_sectors;
182 }
183}
184
185EXPORT_SYMBOL(blk_queue_max_sectors);
186
187/**
188 * blk_queue_max_phys_segments - set max phys segments for a request for this queue
189 * @q: the request queue for the device
190 * @max_segments: max number of segments
191 *
192 * Description:
193 * Enables a low level driver to set an upper limit on the number of
194 * physical data segments in a request. This would be the largest sized
195 * scatter list the driver could handle.
196 **/
197void blk_queue_max_phys_segments(struct request_queue *q,
198 unsigned short max_segments)
199{
200 if (!max_segments) {
201 max_segments = 1;
202 printk("%s: set to minimum %d\n", __FUNCTION__, max_segments);
203 }
204
205 q->max_phys_segments = max_segments;
206}
207
208EXPORT_SYMBOL(blk_queue_max_phys_segments);
209
210/**
211 * blk_queue_max_hw_segments - set max hw segments for a request for this queue
212 * @q: the request queue for the device
213 * @max_segments: max number of segments
214 *
215 * Description:
216 * Enables a low level driver to set an upper limit on the number of
217 * hw data segments in a request. This would be the largest number of
218 * address/length pairs the host adapter can actually give as once
219 * to the device.
220 **/
221void blk_queue_max_hw_segments(struct request_queue *q,
222 unsigned short max_segments)
223{
224 if (!max_segments) {
225 max_segments = 1;
226 printk("%s: set to minimum %d\n", __FUNCTION__, max_segments);
227 }
228
229 q->max_hw_segments = max_segments;
230}
231
232EXPORT_SYMBOL(blk_queue_max_hw_segments);
233
234/**
235 * blk_queue_max_segment_size - set max segment size for blk_rq_map_sg
236 * @q: the request queue for the device
237 * @max_size: max size of segment in bytes
238 *
239 * Description:
240 * Enables a low level driver to set an upper limit on the size of a
241 * coalesced segment
242 **/
243void blk_queue_max_segment_size(struct request_queue *q, unsigned int max_size)
244{
245 if (max_size < PAGE_CACHE_SIZE) {
246 max_size = PAGE_CACHE_SIZE;
247 printk("%s: set to minimum %d\n", __FUNCTION__, max_size);
248 }
249
250 q->max_segment_size = max_size;
251}
252
253EXPORT_SYMBOL(blk_queue_max_segment_size);
254
255/**
256 * blk_queue_hardsect_size - set hardware sector size for the queue
257 * @q: the request queue for the device
258 * @size: the hardware sector size, in bytes
259 *
260 * Description:
261 * This should typically be set to the lowest possible sector size
262 * that the hardware can operate on (possible without reverting to
263 * even internal read-modify-write operations). Usually the default
264 * of 512 covers most hardware.
265 **/
266void blk_queue_hardsect_size(struct request_queue *q, unsigned short size)
267{
268 q->hardsect_size = size;
269}
270
271EXPORT_SYMBOL(blk_queue_hardsect_size);
272
273/*
274 * Returns the minimum that is _not_ zero, unless both are zero.
275 */
276#define min_not_zero(l, r) (l == 0) ? r : ((r == 0) ? l : min(l, r))
277
278/**
279 * blk_queue_stack_limits - inherit underlying queue limits for stacked drivers
280 * @t: the stacking driver (top)
281 * @b: the underlying device (bottom)
282 **/
283void blk_queue_stack_limits(struct request_queue *t, struct request_queue *b)
284{
285 /* zero is "infinity" */
286 t->max_sectors = min_not_zero(t->max_sectors,b->max_sectors);
287 t->max_hw_sectors = min_not_zero(t->max_hw_sectors,b->max_hw_sectors);
288
289 t->max_phys_segments = min(t->max_phys_segments,b->max_phys_segments);
290 t->max_hw_segments = min(t->max_hw_segments,b->max_hw_segments);
291 t->max_segment_size = min(t->max_segment_size,b->max_segment_size);
292 t->hardsect_size = max(t->hardsect_size,b->hardsect_size);
293 if (!test_bit(QUEUE_FLAG_CLUSTER, &b->queue_flags))
294 clear_bit(QUEUE_FLAG_CLUSTER, &t->queue_flags);
295}
296
297EXPORT_SYMBOL(blk_queue_stack_limits);
298
299/**
300 * blk_queue_dma_drain - Set up a drain buffer for excess dma.
301 *
302 * @q: the request queue for the device
303 * @buf: physically contiguous buffer
304 * @size: size of the buffer in bytes
305 *
306 * Some devices have excess DMA problems and can't simply discard (or
307 * zero fill) the unwanted piece of the transfer. They have to have a
308 * real area of memory to transfer it into. The use case for this is
309 * ATAPI devices in DMA mode. If the packet command causes a transfer
310 * bigger than the transfer size some HBAs will lock up if there
311 * aren't DMA elements to contain the excess transfer. What this API
312 * does is adjust the queue so that the buf is always appended
313 * silently to the scatterlist.
314 *
315 * Note: This routine adjusts max_hw_segments to make room for
316 * appending the drain buffer. If you call
317 * blk_queue_max_hw_segments() or blk_queue_max_phys_segments() after
318 * calling this routine, you must set the limit to one fewer than your
319 * device can support otherwise there won't be room for the drain
320 * buffer.
321 */
322int blk_queue_dma_drain(struct request_queue *q, void *buf,
323 unsigned int size)
324{
325 if (q->max_hw_segments < 2 || q->max_phys_segments < 2)
326 return -EINVAL;
327 /* make room for appending the drain */
328 --q->max_hw_segments;
329 --q->max_phys_segments;
330 q->dma_drain_buffer = buf;
331 q->dma_drain_size = size;
332
333 return 0;
334}
335
336EXPORT_SYMBOL_GPL(blk_queue_dma_drain);
337
338/**
339 * blk_queue_segment_boundary - set boundary rules for segment merging
340 * @q: the request queue for the device
341 * @mask: the memory boundary mask
342 **/
343void blk_queue_segment_boundary(struct request_queue *q, unsigned long mask)
344{
345 if (mask < PAGE_CACHE_SIZE - 1) {
346 mask = PAGE_CACHE_SIZE - 1;
347 printk("%s: set to minimum %lx\n", __FUNCTION__, mask);
348 }
349
350 q->seg_boundary_mask = mask;
351}
352
353EXPORT_SYMBOL(blk_queue_segment_boundary);
354
355/**
356 * blk_queue_dma_alignment - set dma length and memory alignment
357 * @q: the request queue for the device
358 * @mask: alignment mask
359 *
360 * description:
361 * set required memory and length aligment for direct dma transactions.
362 * this is used when buiding direct io requests for the queue.
363 *
364 **/
365void blk_queue_dma_alignment(struct request_queue *q, int mask)
366{
367 q->dma_alignment = mask;
368}
369
370EXPORT_SYMBOL(blk_queue_dma_alignment);
371
372/**
373 * blk_queue_update_dma_alignment - update dma length and memory alignment
374 * @q: the request queue for the device
375 * @mask: alignment mask
376 *
377 * description:
378 * update required memory and length aligment for direct dma transactions.
379 * If the requested alignment is larger than the current alignment, then
380 * the current queue alignment is updated to the new value, otherwise it
381 * is left alone. The design of this is to allow multiple objects
382 * (driver, device, transport etc) to set their respective
383 * alignments without having them interfere.
384 *
385 **/
386void blk_queue_update_dma_alignment(struct request_queue *q, int mask)
387{
388 BUG_ON(mask > PAGE_SIZE);
389
390 if (mask > q->dma_alignment)
391 q->dma_alignment = mask;
392}
393
394EXPORT_SYMBOL(blk_queue_update_dma_alignment);
395
396int __init blk_settings_init(void)
397{
398 blk_max_low_pfn = max_low_pfn - 1;
399 blk_max_pfn = max_pfn - 1;
400 return 0;
401}
402subsys_initcall(blk_settings_init);