blob: 1748e27501cdee45da304d4cdfd97f1c0ff37372 [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * scsi_lib.c Copyright (C) 1999 Eric Youngdale
3 *
4 * SCSI queueing library.
5 * Initial versions: Eric Youngdale (eric@andante.org).
6 * Based upon conversations with large numbers
7 * of people at Linux Expo.
8 */
9
10#include <linux/bio.h>
11#include <linux/blkdev.h>
12#include <linux/completion.h>
13#include <linux/kernel.h>
14#include <linux/mempool.h>
15#include <linux/slab.h>
16#include <linux/init.h>
17#include <linux/pci.h>
18#include <linux/delay.h>
James Bottomleyfaead262006-02-14 10:42:07 -060019#include <linux/hardirq.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070020
21#include <scsi/scsi.h>
Christoph Hellwigbeb40482006-06-10 18:01:03 +020022#include <scsi/scsi_cmnd.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070023#include <scsi/scsi_dbg.h>
24#include <scsi/scsi_device.h>
25#include <scsi/scsi_driver.h>
26#include <scsi/scsi_eh.h>
27#include <scsi/scsi_host.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070028
29#include "scsi_priv.h"
30#include "scsi_logging.h"
31
32
Tobias Klauser6391a112006-06-08 22:23:48 -070033#define SG_MEMPOOL_NR ARRAY_SIZE(scsi_sg_pools)
Linus Torvalds1da177e2005-04-16 15:20:36 -070034#define SG_MEMPOOL_SIZE 32
35
36struct scsi_host_sg_pool {
37 size_t size;
38 char *name;
Christoph Lametere18b8902006-12-06 20:33:20 -080039 struct kmem_cache *slab;
Linus Torvalds1da177e2005-04-16 15:20:36 -070040 mempool_t *pool;
41};
42
43#if (SCSI_MAX_PHYS_SEGMENTS < 32)
44#error SCSI_MAX_PHYS_SEGMENTS is too small
45#endif
46
47#define SP(x) { x, "sgpool-" #x }
Adrian Bunk52c1da32005-06-23 22:05:33 -070048static struct scsi_host_sg_pool scsi_sg_pools[] = {
Linus Torvalds1da177e2005-04-16 15:20:36 -070049 SP(8),
50 SP(16),
51 SP(32),
52#if (SCSI_MAX_PHYS_SEGMENTS > 32)
53 SP(64),
54#if (SCSI_MAX_PHYS_SEGMENTS > 64)
55 SP(128),
56#if (SCSI_MAX_PHYS_SEGMENTS > 128)
57 SP(256),
58#if (SCSI_MAX_PHYS_SEGMENTS > 256)
59#error SCSI_MAX_PHYS_SEGMENTS is too large
60#endif
61#endif
62#endif
63#endif
64};
65#undef SP
66
Tejun Heo a1bf9d1d2005-04-24 02:08:52 -050067static void scsi_run_queue(struct request_queue *q);
James Bottomleye91442b2005-09-09 10:44:16 -050068
69/*
70 * Function: scsi_unprep_request()
71 *
72 * Purpose: Remove all preparation done for a request, including its
73 * associated scsi_cmnd, so that it can be requeued.
74 *
75 * Arguments: req - request to unprepare
76 *
77 * Lock status: Assumed that no locks are held upon entry.
78 *
79 * Returns: Nothing.
80 */
81static void scsi_unprep_request(struct request *req)
82{
83 struct scsi_cmnd *cmd = req->special;
84
Jens Axboe4aff5e22006-08-10 08:44:47 +020085 req->cmd_flags &= ~REQ_DONTPREP;
Christoph Hellwigbeb40482006-06-10 18:01:03 +020086 req->special = NULL;
James Bottomleye91442b2005-09-09 10:44:16 -050087
James Bottomleye91442b2005-09-09 10:44:16 -050088 scsi_put_command(cmd);
89}
Tejun Heo a1bf9d1d2005-04-24 02:08:52 -050090
Linus Torvalds1da177e2005-04-16 15:20:36 -070091/*
92 * Function: scsi_queue_insert()
93 *
94 * Purpose: Insert a command in the midlevel queue.
95 *
96 * Arguments: cmd - command that we are adding to queue.
97 * reason - why we are inserting command to queue.
98 *
99 * Lock status: Assumed that lock is not held upon entry.
100 *
101 * Returns: Nothing.
102 *
103 * Notes: We do this for one of two cases. Either the host is busy
104 * and it cannot accept any more commands for the time being,
105 * or the device returned QUEUE_FULL and can accept no more
106 * commands.
107 * Notes: This could be called either from an interrupt context or a
108 * normal process context.
109 */
110int scsi_queue_insert(struct scsi_cmnd *cmd, int reason)
111{
112 struct Scsi_Host *host = cmd->device->host;
113 struct scsi_device *device = cmd->device;
Tejun Heo a1bf9d1d2005-04-24 02:08:52 -0500114 struct request_queue *q = device->request_queue;
115 unsigned long flags;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700116
117 SCSI_LOG_MLQUEUE(1,
118 printk("Inserting command %p into mlqueue\n", cmd));
119
120 /*
Tejun Heo d8c37e72005-05-14 00:46:08 +0900121 * Set the appropriate busy bit for the device/host.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700122 *
123 * If the host/device isn't busy, assume that something actually
124 * completed, and that we should be able to queue a command now.
125 *
126 * Note that the prior mid-layer assumption that any host could
127 * always queue at least one command is now broken. The mid-layer
128 * will implement a user specifiable stall (see
129 * scsi_host.max_host_blocked and scsi_device.max_device_blocked)
130 * if a command is requeued with no other commands outstanding
131 * either for the device or for the host.
132 */
133 if (reason == SCSI_MLQUEUE_HOST_BUSY)
134 host->host_blocked = host->max_host_blocked;
135 else if (reason == SCSI_MLQUEUE_DEVICE_BUSY)
136 device->device_blocked = device->max_device_blocked;
137
138 /*
Linus Torvalds1da177e2005-04-16 15:20:36 -0700139 * Decrement the counters, since these commands are no longer
140 * active on the host/device.
141 */
142 scsi_device_unbusy(device);
143
144 /*
Tejun Heo a1bf9d1d2005-04-24 02:08:52 -0500145 * Requeue this command. It will go before all other commands
146 * that are already in the queue.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700147 *
148 * NOTE: there is magic here about the way the queue is plugged if
149 * we have no outstanding commands.
150 *
Tejun Heo a1bf9d1d2005-04-24 02:08:52 -0500151 * Although we *don't* plug the queue, we call the request
Linus Torvalds1da177e2005-04-16 15:20:36 -0700152 * function. The SCSI request function detects the blocked condition
153 * and plugs the queue appropriately.
Tejun Heo a1bf9d1d2005-04-24 02:08:52 -0500154 */
155 spin_lock_irqsave(q->queue_lock, flags);
James Bottomley59897da2005-09-14 12:57:42 -0400156 blk_requeue_request(q, cmd->request);
Tejun Heo a1bf9d1d2005-04-24 02:08:52 -0500157 spin_unlock_irqrestore(q->queue_lock, flags);
158
159 scsi_run_queue(q);
160
Linus Torvalds1da177e2005-04-16 15:20:36 -0700161 return 0;
162}
163
James Bottomley39216032005-06-15 18:48:29 -0500164/**
James Bottomley33aa6872005-08-28 11:31:14 -0500165 * scsi_execute - insert request and wait for the result
James Bottomley39216032005-06-15 18:48:29 -0500166 * @sdev: scsi device
167 * @cmd: scsi command
168 * @data_direction: data direction
169 * @buffer: data buffer
170 * @bufflen: len of buffer
171 * @sense: optional sense buffer
172 * @timeout: request timeout in seconds
173 * @retries: number of times to retry request
James Bottomley33aa6872005-08-28 11:31:14 -0500174 * @flags: or into request flags;
James Bottomley39216032005-06-15 18:48:29 -0500175 *
James Bottomleyea73a9f2005-08-28 11:33:52 -0500176 * returns the req->errors value which is the the scsi_cmnd result
177 * field.
James Bottomley39216032005-06-15 18:48:29 -0500178 **/
James Bottomley33aa6872005-08-28 11:31:14 -0500179int scsi_execute(struct scsi_device *sdev, const unsigned char *cmd,
180 int data_direction, void *buffer, unsigned bufflen,
181 unsigned char *sense, int timeout, int retries, int flags)
James Bottomley39216032005-06-15 18:48:29 -0500182{
183 struct request *req;
184 int write = (data_direction == DMA_TO_DEVICE);
185 int ret = DRIVER_ERROR << 24;
186
187 req = blk_get_request(sdev->request_queue, write, __GFP_WAIT);
188
189 if (bufflen && blk_rq_map_kern(sdev->request_queue, req,
190 buffer, bufflen, __GFP_WAIT))
191 goto out;
192
193 req->cmd_len = COMMAND_SIZE(cmd[0]);
194 memcpy(req->cmd, cmd, req->cmd_len);
195 req->sense = sense;
196 req->sense_len = 0;
Mike Christie17e01f22005-11-11 05:31:37 -0600197 req->retries = retries;
James Bottomley39216032005-06-15 18:48:29 -0500198 req->timeout = timeout;
Jens Axboe4aff5e22006-08-10 08:44:47 +0200199 req->cmd_type = REQ_TYPE_BLOCK_PC;
200 req->cmd_flags |= flags | REQ_QUIET | REQ_PREEMPT;
James Bottomley39216032005-06-15 18:48:29 -0500201
202 /*
203 * head injection *required* here otherwise quiesce won't work
204 */
205 blk_execute_rq(req->q, NULL, req, 1);
206
207 ret = req->errors;
208 out:
209 blk_put_request(req);
210
211 return ret;
212}
James Bottomley33aa6872005-08-28 11:31:14 -0500213EXPORT_SYMBOL(scsi_execute);
James Bottomley39216032005-06-15 18:48:29 -0500214
James Bottomleyea73a9f2005-08-28 11:33:52 -0500215
216int scsi_execute_req(struct scsi_device *sdev, const unsigned char *cmd,
217 int data_direction, void *buffer, unsigned bufflen,
218 struct scsi_sense_hdr *sshdr, int timeout, int retries)
219{
220 char *sense = NULL;
akpm@osdl.org1ccb48b2005-06-26 00:12:51 -0700221 int result;
222
James Bottomleyea73a9f2005-08-28 11:33:52 -0500223 if (sshdr) {
Jes Sorensen24669f752006-01-16 10:31:18 -0500224 sense = kzalloc(SCSI_SENSE_BUFFERSIZE, GFP_NOIO);
James Bottomleyea73a9f2005-08-28 11:33:52 -0500225 if (!sense)
226 return DRIVER_ERROR << 24;
James Bottomleyea73a9f2005-08-28 11:33:52 -0500227 }
akpm@osdl.org1ccb48b2005-06-26 00:12:51 -0700228 result = scsi_execute(sdev, cmd, data_direction, buffer, bufflen,
Jes Sorensen24669f752006-01-16 10:31:18 -0500229 sense, timeout, retries, 0);
James Bottomleyea73a9f2005-08-28 11:33:52 -0500230 if (sshdr)
James Bottomleye5143852005-08-09 11:55:36 -0500231 scsi_normalize_sense(sense, SCSI_SENSE_BUFFERSIZE, sshdr);
James Bottomleyea73a9f2005-08-28 11:33:52 -0500232
233 kfree(sense);
234 return result;
235}
236EXPORT_SYMBOL(scsi_execute_req);
237
Mike Christie6e68af62005-11-11 05:30:27 -0600238struct scsi_io_context {
239 void *data;
240 void (*done)(void *data, char *sense, int result, int resid);
241 char sense[SCSI_SENSE_BUFFERSIZE];
242};
243
Christoph Lametere18b8902006-12-06 20:33:20 -0800244static struct kmem_cache *scsi_io_context_cache;
Mike Christieaa7b5cd2005-11-11 05:31:41 -0600245
Jens Axboee650c302006-01-06 12:38:30 +0100246static void scsi_end_async(struct request *req, int uptodate)
Mike Christie6e68af62005-11-11 05:30:27 -0600247{
248 struct scsi_io_context *sioc = req->end_io_data;
249
250 if (sioc->done)
251 sioc->done(sioc->data, sioc->sense, req->errors, req->data_len);
252
Mike Christieaa7b5cd2005-11-11 05:31:41 -0600253 kmem_cache_free(scsi_io_context_cache, sioc);
Mike Christie6e68af62005-11-11 05:30:27 -0600254 __blk_put_request(req->q, req);
255}
256
257static int scsi_merge_bio(struct request *rq, struct bio *bio)
258{
259 struct request_queue *q = rq->q;
260
261 bio->bi_flags &= ~(1 << BIO_SEG_VALID);
262 if (rq_data_dir(rq) == WRITE)
263 bio->bi_rw |= (1 << BIO_RW);
264 blk_queue_bounce(q, &bio);
265
266 if (!rq->bio)
267 blk_rq_bio_prep(q, rq, bio);
268 else if (!q->back_merge_fn(q, rq, bio))
269 return -EINVAL;
270 else {
271 rq->biotail->bi_next = bio;
272 rq->biotail = bio;
273 rq->hard_nr_sectors += bio_sectors(bio);
274 rq->nr_sectors = rq->hard_nr_sectors;
275 }
276
277 return 0;
278}
279
280static int scsi_bi_endio(struct bio *bio, unsigned int bytes_done, int error)
281{
282 if (bio->bi_size)
283 return 1;
284
285 bio_put(bio);
286 return 0;
287}
288
289/**
290 * scsi_req_map_sg - map a scatterlist into a request
291 * @rq: request to fill
292 * @sg: scatterlist
293 * @nsegs: number of elements
294 * @bufflen: len of buffer
295 * @gfp: memory allocation flags
296 *
297 * scsi_req_map_sg maps a scatterlist into a request so that the
298 * request can be sent to the block layer. We do not trust the scatterlist
299 * sent to use, as some ULDs use that struct to only organize the pages.
300 */
301static int scsi_req_map_sg(struct request *rq, struct scatterlist *sgl,
302 int nsegs, unsigned bufflen, gfp_t gfp)
303{
304 struct request_queue *q = rq->q;
Bryan Holtyf5235962006-03-22 06:35:39 -0600305 int nr_pages = (bufflen + sgl[0].offset + PAGE_SIZE - 1) >> PAGE_SHIFT;
Mike Christie6e68af62005-11-11 05:30:27 -0600306 unsigned int data_len = 0, len, bytes, off;
307 struct page *page;
308 struct bio *bio = NULL;
309 int i, err, nr_vecs = 0;
310
311 for (i = 0; i < nsegs; i++) {
312 page = sgl[i].page;
313 off = sgl[i].offset;
314 len = sgl[i].length;
315 data_len += len;
316
317 while (len > 0) {
318 bytes = min_t(unsigned int, len, PAGE_SIZE - off);
319
320 if (!bio) {
321 nr_vecs = min_t(int, BIO_MAX_PAGES, nr_pages);
322 nr_pages -= nr_vecs;
323
324 bio = bio_alloc(gfp, nr_vecs);
325 if (!bio) {
326 err = -ENOMEM;
327 goto free_bios;
328 }
329 bio->bi_end_io = scsi_bi_endio;
330 }
331
332 if (bio_add_pc_page(q, bio, page, bytes, off) !=
333 bytes) {
334 bio_put(bio);
335 err = -EINVAL;
336 goto free_bios;
337 }
338
339 if (bio->bi_vcnt >= nr_vecs) {
340 err = scsi_merge_bio(rq, bio);
341 if (err) {
342 bio_endio(bio, bio->bi_size, 0);
343 goto free_bios;
344 }
345 bio = NULL;
346 }
347
348 page++;
349 len -= bytes;
350 off = 0;
351 }
352 }
353
354 rq->buffer = rq->data = NULL;
355 rq->data_len = data_len;
356 return 0;
357
358free_bios:
359 while ((bio = rq->bio) != NULL) {
360 rq->bio = bio->bi_next;
361 /*
362 * call endio instead of bio_put incase it was bounced
363 */
364 bio_endio(bio, bio->bi_size, 0);
365 }
366
367 return err;
368}
369
370/**
371 * scsi_execute_async - insert request
372 * @sdev: scsi device
373 * @cmd: scsi command
brking@us.ibm.combb1d1072006-01-23 15:03:22 -0600374 * @cmd_len: length of scsi cdb
Mike Christie6e68af62005-11-11 05:30:27 -0600375 * @data_direction: data direction
376 * @buffer: data buffer (this can be a kernel buffer or scatterlist)
377 * @bufflen: len of buffer
378 * @use_sg: if buffer is a scatterlist this is the number of elements
379 * @timeout: request timeout in seconds
380 * @retries: number of times to retry request
381 * @flags: or into request flags
382 **/
383int scsi_execute_async(struct scsi_device *sdev, const unsigned char *cmd,
brking@us.ibm.combb1d1072006-01-23 15:03:22 -0600384 int cmd_len, int data_direction, void *buffer, unsigned bufflen,
Mike Christie6e68af62005-11-11 05:30:27 -0600385 int use_sg, int timeout, int retries, void *privdata,
386 void (*done)(void *, char *, int, int), gfp_t gfp)
387{
388 struct request *req;
389 struct scsi_io_context *sioc;
390 int err = 0;
391 int write = (data_direction == DMA_TO_DEVICE);
392
Mike Christieaa7b5cd2005-11-11 05:31:41 -0600393 sioc = kmem_cache_alloc(scsi_io_context_cache, gfp);
Mike Christie6e68af62005-11-11 05:30:27 -0600394 if (!sioc)
395 return DRIVER_ERROR << 24;
Mike Christieaa7b5cd2005-11-11 05:31:41 -0600396 memset(sioc, 0, sizeof(*sioc));
Mike Christie6e68af62005-11-11 05:30:27 -0600397
398 req = blk_get_request(sdev->request_queue, write, gfp);
399 if (!req)
400 goto free_sense;
Jens Axboe4aff5e22006-08-10 08:44:47 +0200401 req->cmd_type = REQ_TYPE_BLOCK_PC;
402 req->cmd_flags |= REQ_QUIET;
Mike Christie6e68af62005-11-11 05:30:27 -0600403
404 if (use_sg)
405 err = scsi_req_map_sg(req, buffer, use_sg, bufflen, gfp);
406 else if (bufflen)
407 err = blk_rq_map_kern(req->q, req, buffer, bufflen, gfp);
408
409 if (err)
410 goto free_req;
411
brking@us.ibm.combb1d1072006-01-23 15:03:22 -0600412 req->cmd_len = cmd_len;
Tejun Heo097b8452006-11-16 01:19:31 -0800413 memset(req->cmd, 0, BLK_MAX_CDB); /* ATAPI hates garbage after CDB */
Mike Christie6e68af62005-11-11 05:30:27 -0600414 memcpy(req->cmd, cmd, req->cmd_len);
415 req->sense = sioc->sense;
416 req->sense_len = 0;
417 req->timeout = timeout;
Mike Christie17e01f22005-11-11 05:31:37 -0600418 req->retries = retries;
Mike Christie6e68af62005-11-11 05:30:27 -0600419 req->end_io_data = sioc;
420
421 sioc->data = privdata;
422 sioc->done = done;
423
424 blk_execute_rq_nowait(req->q, NULL, req, 1, scsi_end_async);
425 return 0;
426
427free_req:
428 blk_put_request(req);
429free_sense:
Arne Redlich6470f2b2006-09-30 15:49:40 +0200430 kmem_cache_free(scsi_io_context_cache, sioc);
Mike Christie6e68af62005-11-11 05:30:27 -0600431 return DRIVER_ERROR << 24;
432}
433EXPORT_SYMBOL_GPL(scsi_execute_async);
434
Linus Torvalds1da177e2005-04-16 15:20:36 -0700435/*
436 * Function: scsi_init_cmd_errh()
437 *
438 * Purpose: Initialize cmd fields related to error handling.
439 *
440 * Arguments: cmd - command that is ready to be queued.
441 *
Linus Torvalds1da177e2005-04-16 15:20:36 -0700442 * Notes: This function has the job of initializing a number of
443 * fields related to error handling. Typically this will
444 * be called once for each command, as required.
445 */
Christoph Hellwig631c2282006-07-08 20:42:15 +0200446static void scsi_init_cmd_errh(struct scsi_cmnd *cmd)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700447{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700448 cmd->serial_number = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700449 memset(cmd->sense_buffer, 0, sizeof cmd->sense_buffer);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700450 if (cmd->cmd_len == 0)
451 cmd->cmd_len = COMMAND_SIZE(cmd->cmnd[0]);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700452}
453
454void scsi_device_unbusy(struct scsi_device *sdev)
455{
456 struct Scsi_Host *shost = sdev->host;
457 unsigned long flags;
458
459 spin_lock_irqsave(shost->host_lock, flags);
460 shost->host_busy--;
James Bottomley939647e2005-09-18 15:05:20 -0500461 if (unlikely(scsi_host_in_recovery(shost) &&
Tejun Heoee7863b2006-05-15 20:57:20 +0900462 (shost->host_failed || shost->host_eh_scheduled)))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700463 scsi_eh_wakeup(shost);
464 spin_unlock(shost->host_lock);
152587d2005-04-12 16:22:06 -0500465 spin_lock(sdev->request_queue->queue_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700466 sdev->device_busy--;
152587d2005-04-12 16:22:06 -0500467 spin_unlock_irqrestore(sdev->request_queue->queue_lock, flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700468}
469
470/*
471 * Called for single_lun devices on IO completion. Clear starget_sdev_user,
472 * and call blk_run_queue for all the scsi_devices on the target -
473 * including current_sdev first.
474 *
475 * Called with *no* scsi locks held.
476 */
477static void scsi_single_lun_run(struct scsi_device *current_sdev)
478{
479 struct Scsi_Host *shost = current_sdev->host;
480 struct scsi_device *sdev, *tmp;
481 struct scsi_target *starget = scsi_target(current_sdev);
482 unsigned long flags;
483
484 spin_lock_irqsave(shost->host_lock, flags);
485 starget->starget_sdev_user = NULL;
486 spin_unlock_irqrestore(shost->host_lock, flags);
487
488 /*
489 * Call blk_run_queue for all LUNs on the target, starting with
490 * current_sdev. We race with others (to set starget_sdev_user),
491 * but in most cases, we will be first. Ideally, each LU on the
492 * target would get some limited time or requests on the target.
493 */
494 blk_run_queue(current_sdev->request_queue);
495
496 spin_lock_irqsave(shost->host_lock, flags);
497 if (starget->starget_sdev_user)
498 goto out;
499 list_for_each_entry_safe(sdev, tmp, &starget->devices,
500 same_target_siblings) {
501 if (sdev == current_sdev)
502 continue;
503 if (scsi_device_get(sdev))
504 continue;
505
506 spin_unlock_irqrestore(shost->host_lock, flags);
507 blk_run_queue(sdev->request_queue);
508 spin_lock_irqsave(shost->host_lock, flags);
509
510 scsi_device_put(sdev);
511 }
512 out:
513 spin_unlock_irqrestore(shost->host_lock, flags);
514}
515
516/*
517 * Function: scsi_run_queue()
518 *
519 * Purpose: Select a proper request queue to serve next
520 *
521 * Arguments: q - last request's queue
522 *
523 * Returns: Nothing
524 *
525 * Notes: The previous command was completely finished, start
526 * a new one if possible.
527 */
528static void scsi_run_queue(struct request_queue *q)
529{
530 struct scsi_device *sdev = q->queuedata;
531 struct Scsi_Host *shost = sdev->host;
532 unsigned long flags;
533
534 if (sdev->single_lun)
535 scsi_single_lun_run(sdev);
536
537 spin_lock_irqsave(shost->host_lock, flags);
538 while (!list_empty(&shost->starved_list) &&
539 !shost->host_blocked && !shost->host_self_blocked &&
540 !((shost->can_queue > 0) &&
541 (shost->host_busy >= shost->can_queue))) {
542 /*
543 * As long as shost is accepting commands and we have
544 * starved queues, call blk_run_queue. scsi_request_fn
545 * drops the queue_lock and can add us back to the
546 * starved_list.
547 *
548 * host_lock protects the starved_list and starved_entry.
549 * scsi_request_fn must get the host_lock before checking
550 * or modifying starved_list or starved_entry.
551 */
552 sdev = list_entry(shost->starved_list.next,
553 struct scsi_device, starved_entry);
554 list_del_init(&sdev->starved_entry);
555 spin_unlock_irqrestore(shost->host_lock, flags);
556
Andreas Herrmann04846f22006-08-09 17:31:16 +0200557
558 if (test_bit(QUEUE_FLAG_REENTER, &q->queue_flags) &&
559 !test_and_set_bit(QUEUE_FLAG_REENTER,
560 &sdev->request_queue->queue_flags)) {
561 blk_run_queue(sdev->request_queue);
562 clear_bit(QUEUE_FLAG_REENTER,
563 &sdev->request_queue->queue_flags);
564 } else
565 blk_run_queue(sdev->request_queue);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700566
567 spin_lock_irqsave(shost->host_lock, flags);
568 if (unlikely(!list_empty(&sdev->starved_entry)))
569 /*
570 * sdev lost a race, and was put back on the
571 * starved list. This is unlikely but without this
572 * in theory we could loop forever.
573 */
574 break;
575 }
576 spin_unlock_irqrestore(shost->host_lock, flags);
577
578 blk_run_queue(q);
579}
580
581/*
582 * Function: scsi_requeue_command()
583 *
584 * Purpose: Handle post-processing of completed commands.
585 *
586 * Arguments: q - queue to operate on
587 * cmd - command that may need to be requeued.
588 *
589 * Returns: Nothing
590 *
591 * Notes: After command completion, there may be blocks left
592 * over which weren't finished by the previous command
593 * this can be for a number of reasons - the main one is
594 * I/O errors in the middle of the request, in which case
595 * we need to request the blocks that come after the bad
596 * sector.
James Bottomleye91442b2005-09-09 10:44:16 -0500597 * Notes: Upon return, cmd is a stale pointer.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700598 */
599static void scsi_requeue_command(struct request_queue *q, struct scsi_cmnd *cmd)
600{
James Bottomleye91442b2005-09-09 10:44:16 -0500601 struct request *req = cmd->request;
Tejun Heo 283369c2005-04-24 02:06:36 -0500602 unsigned long flags;
603
James Bottomleye91442b2005-09-09 10:44:16 -0500604 scsi_unprep_request(req);
Tejun Heo 283369c2005-04-24 02:06:36 -0500605 spin_lock_irqsave(q->queue_lock, flags);
James Bottomleye91442b2005-09-09 10:44:16 -0500606 blk_requeue_request(q, req);
Tejun Heo 283369c2005-04-24 02:06:36 -0500607 spin_unlock_irqrestore(q->queue_lock, flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700608
609 scsi_run_queue(q);
610}
611
612void scsi_next_command(struct scsi_cmnd *cmd)
613{
Linus Torvalds49d7bc62005-12-12 11:25:04 -0800614 struct scsi_device *sdev = cmd->device;
615 struct request_queue *q = sdev->request_queue;
616
617 /* need to hold a reference on the device before we let go of the cmd */
618 get_device(&sdev->sdev_gendev);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700619
620 scsi_put_command(cmd);
621 scsi_run_queue(q);
Linus Torvalds49d7bc62005-12-12 11:25:04 -0800622
623 /* ok to remove device now */
624 put_device(&sdev->sdev_gendev);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700625}
626
627void scsi_run_host_queues(struct Scsi_Host *shost)
628{
629 struct scsi_device *sdev;
630
631 shost_for_each_device(sdev, shost)
632 scsi_run_queue(sdev->request_queue);
633}
634
635/*
636 * Function: scsi_end_request()
637 *
638 * Purpose: Post-processing of completed commands (usually invoked at end
639 * of upper level post-processing and scsi_io_completion).
640 *
641 * Arguments: cmd - command that is complete.
642 * uptodate - 1 if I/O indicates success, <= 0 for I/O error.
643 * bytes - number of bytes of completed I/O
644 * requeue - indicates whether we should requeue leftovers.
645 *
646 * Lock status: Assumed that lock is not held upon entry.
647 *
James Bottomleye91442b2005-09-09 10:44:16 -0500648 * Returns: cmd if requeue required, NULL otherwise.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700649 *
650 * Notes: This is called for block device requests in order to
651 * mark some number of sectors as complete.
652 *
653 * We are guaranteeing that the request queue will be goosed
654 * at some point during this call.
James Bottomleye91442b2005-09-09 10:44:16 -0500655 * Notes: If cmd was requeued, upon return it will be a stale pointer.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700656 */
657static struct scsi_cmnd *scsi_end_request(struct scsi_cmnd *cmd, int uptodate,
658 int bytes, int requeue)
659{
660 request_queue_t *q = cmd->device->request_queue;
661 struct request *req = cmd->request;
662 unsigned long flags;
663
664 /*
665 * If there are blocks left over at the end, set up the command
666 * to queue the remainder of them.
667 */
668 if (end_that_request_chunk(req, uptodate, bytes)) {
669 int leftover = (req->hard_nr_sectors << 9);
670
671 if (blk_pc_request(req))
672 leftover = req->data_len;
673
674 /* kill remainder if no retrys */
675 if (!uptodate && blk_noretry_request(req))
676 end_that_request_chunk(req, 0, leftover);
677 else {
James Bottomleye91442b2005-09-09 10:44:16 -0500678 if (requeue) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700679 /*
680 * Bleah. Leftovers again. Stick the
681 * leftovers in the front of the
682 * queue, and goose the queue again.
683 */
684 scsi_requeue_command(q, cmd);
James Bottomleye91442b2005-09-09 10:44:16 -0500685 cmd = NULL;
686 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700687 return cmd;
688 }
689 }
690
691 add_disk_randomness(req->rq_disk);
692
693 spin_lock_irqsave(q->queue_lock, flags);
694 if (blk_rq_tagged(req))
695 blk_queue_end_tag(q, req);
Tejun Heo8ffdc652006-01-06 09:49:03 +0100696 end_that_request_last(req, uptodate);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700697 spin_unlock_irqrestore(q->queue_lock, flags);
698
699 /*
700 * This will goose the queue request function at the end, so we don't
701 * need to worry about launching another command.
702 */
703 scsi_next_command(cmd);
704 return NULL;
705}
706
FUJITA Tomonorib58d9152006-11-16 19:24:10 +0900707struct scatterlist *scsi_alloc_sgtable(struct scsi_cmnd *cmd, gfp_t gfp_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700708{
709 struct scsi_host_sg_pool *sgp;
710 struct scatterlist *sgl;
711
712 BUG_ON(!cmd->use_sg);
713
714 switch (cmd->use_sg) {
715 case 1 ... 8:
716 cmd->sglist_len = 0;
717 break;
718 case 9 ... 16:
719 cmd->sglist_len = 1;
720 break;
721 case 17 ... 32:
722 cmd->sglist_len = 2;
723 break;
724#if (SCSI_MAX_PHYS_SEGMENTS > 32)
725 case 33 ... 64:
726 cmd->sglist_len = 3;
727 break;
728#if (SCSI_MAX_PHYS_SEGMENTS > 64)
729 case 65 ... 128:
730 cmd->sglist_len = 4;
731 break;
732#if (SCSI_MAX_PHYS_SEGMENTS > 128)
733 case 129 ... 256:
734 cmd->sglist_len = 5;
735 break;
736#endif
737#endif
738#endif
739 default:
740 return NULL;
741 }
742
743 sgp = scsi_sg_pools + cmd->sglist_len;
744 sgl = mempool_alloc(sgp->pool, gfp_mask);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700745 return sgl;
746}
747
FUJITA Tomonorib58d9152006-11-16 19:24:10 +0900748EXPORT_SYMBOL(scsi_alloc_sgtable);
749
750void scsi_free_sgtable(struct scatterlist *sgl, int index)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700751{
752 struct scsi_host_sg_pool *sgp;
753
KAMBAROV, ZAURa77e3362005-06-28 20:45:06 -0700754 BUG_ON(index >= SG_MEMPOOL_NR);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700755
756 sgp = scsi_sg_pools + index;
757 mempool_free(sgl, sgp->pool);
758}
759
FUJITA Tomonorib58d9152006-11-16 19:24:10 +0900760EXPORT_SYMBOL(scsi_free_sgtable);
761
Linus Torvalds1da177e2005-04-16 15:20:36 -0700762/*
763 * Function: scsi_release_buffers()
764 *
765 * Purpose: Completion processing for block device I/O requests.
766 *
767 * Arguments: cmd - command that we are bailing.
768 *
769 * Lock status: Assumed that no lock is held upon entry.
770 *
771 * Returns: Nothing
772 *
773 * Notes: In the event that an upper level driver rejects a
774 * command, we must release resources allocated during
775 * the __init_io() function. Primarily this would involve
776 * the scatter-gather table, and potentially any bounce
777 * buffers.
778 */
779static void scsi_release_buffers(struct scsi_cmnd *cmd)
780{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700781 if (cmd->use_sg)
782 scsi_free_sgtable(cmd->request_buffer, cmd->sglist_len);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700783
784 /*
785 * Zero these out. They now point to freed memory, and it is
786 * dangerous to hang onto the pointers.
787 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700788 cmd->request_buffer = NULL;
789 cmd->request_bufflen = 0;
790}
791
792/*
793 * Function: scsi_io_completion()
794 *
795 * Purpose: Completion processing for block device I/O requests.
796 *
797 * Arguments: cmd - command that is finished.
798 *
799 * Lock status: Assumed that no lock is held upon entry.
800 *
801 * Returns: Nothing
802 *
803 * Notes: This function is matched in terms of capabilities to
804 * the function that created the scatter-gather list.
805 * In other words, if there are no bounce buffers
806 * (the normal case for most drivers), we don't need
807 * the logic to deal with cleaning up afterwards.
808 *
809 * We must do one of several things here:
810 *
811 * a) Call scsi_end_request. This will finish off the
812 * specified number of sectors. If we are done, the
813 * command block will be released, and the queue
814 * function will be goosed. If we are not done, then
815 * scsi_end_request will directly goose the queue.
816 *
817 * b) We can just use scsi_requeue_command() here. This would
818 * be used if we just wanted to retry, for example.
819 */
Luben Tuikov03aba2f2006-06-23 09:39:09 -0700820void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700821{
822 int result = cmd->result;
Christoph Hellwig631c2282006-07-08 20:42:15 +0200823 int this_count = cmd->request_bufflen;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700824 request_queue_t *q = cmd->device->request_queue;
825 struct request *req = cmd->request;
826 int clear_errors = 1;
827 struct scsi_sense_hdr sshdr;
828 int sense_valid = 0;
829 int sense_deferred = 0;
830
Christoph Hellwig631c2282006-07-08 20:42:15 +0200831 scsi_release_buffers(cmd);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700832
833 if (result) {
834 sense_valid = scsi_command_normalize_sense(cmd, &sshdr);
835 if (sense_valid)
836 sense_deferred = scsi_sense_is_deferred(&sshdr);
837 }
Christoph Hellwig631c2282006-07-08 20:42:15 +0200838
Linus Torvalds1da177e2005-04-16 15:20:36 -0700839 if (blk_pc_request(req)) { /* SG_IO ioctl from block level */
840 req->errors = result;
841 if (result) {
842 clear_errors = 0;
843 if (sense_valid && req->sense) {
844 /*
845 * SG_IO wants current and deferred errors
846 */
847 int len = 8 + cmd->sense_buffer[7];
848
849 if (len > SCSI_SENSE_BUFFERSIZE)
850 len = SCSI_SENSE_BUFFERSIZE;
851 memcpy(req->sense, cmd->sense_buffer, len);
852 req->sense_len = len;
853 }
854 } else
855 req->data_len = cmd->resid;
856 }
857
858 /*
Linus Torvalds1da177e2005-04-16 15:20:36 -0700859 * Next deal with any sectors which we were able to correctly
860 * handle.
861 */
James Bottomleyd6b0c532006-07-02 10:06:28 -0500862 SCSI_LOG_HLCOMPLETE(1, printk("%ld sectors total, "
863 "%d bytes done.\n",
864 req->nr_sectors, good_bytes));
865 SCSI_LOG_HLCOMPLETE(1, printk("use_sg is %d\n", cmd->use_sg));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700866
James Bottomleyd6b0c532006-07-02 10:06:28 -0500867 if (clear_errors)
868 req->errors = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700869
James Bottomleyd6b0c532006-07-02 10:06:28 -0500870 /* A number of bytes were successfully read. If there
871 * are leftovers and there is some kind of error
872 * (result != 0), retry the rest.
873 */
874 if (scsi_end_request(cmd, 1, good_bytes, result == 0) == NULL)
875 return;
Luben Tuikov03aba2f2006-06-23 09:39:09 -0700876
877 /* good_bytes = 0, or (inclusive) there were leftovers and
878 * result = 0, so scsi_end_request couldn't retry.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700879 */
880 if (sense_valid && !sense_deferred) {
881 switch (sshdr.sense_key) {
882 case UNIT_ATTENTION:
883 if (cmd->device->removable) {
Luben Tuikov03aba2f2006-06-23 09:39:09 -0700884 /* Detected disc change. Set a bit
Linus Torvalds1da177e2005-04-16 15:20:36 -0700885 * and quietly refuse further access.
886 */
887 cmd->device->changed = 1;
Luben Tuikov03aba2f2006-06-23 09:39:09 -0700888 scsi_end_request(cmd, 0, this_count, 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700889 return;
890 } else {
Luben Tuikov03aba2f2006-06-23 09:39:09 -0700891 /* Must have been a power glitch, or a
892 * bus reset. Could not have been a
893 * media change, so we just retry the
894 * request and see what happens.
895 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700896 scsi_requeue_command(q, cmd);
897 return;
898 }
899 break;
900 case ILLEGAL_REQUEST:
Luben Tuikov03aba2f2006-06-23 09:39:09 -0700901 /* If we had an ILLEGAL REQUEST returned, then
902 * we may have performed an unsupported
903 * command. The only thing this should be
904 * would be a ten byte read where only a six
905 * byte read was supported. Also, on a system
906 * where READ CAPACITY failed, we may have
907 * read past the end of the disk.
908 */
Jens Axboe26a68012005-11-29 21:03:34 +0100909 if ((cmd->device->use_10_for_rw &&
910 sshdr.asc == 0x20 && sshdr.ascq == 0x00) &&
Linus Torvalds1da177e2005-04-16 15:20:36 -0700911 (cmd->cmnd[0] == READ_10 ||
912 cmd->cmnd[0] == WRITE_10)) {
913 cmd->device->use_10_for_rw = 0;
Luben Tuikov03aba2f2006-06-23 09:39:09 -0700914 /* This will cause a retry with a
915 * 6-byte command.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700916 */
917 scsi_requeue_command(q, cmd);
Luben Tuikov03aba2f2006-06-23 09:39:09 -0700918 return;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700919 } else {
James Bottomleye91442b2005-09-09 10:44:16 -0500920 scsi_end_request(cmd, 0, this_count, 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700921 return;
922 }
923 break;
924 case NOT_READY:
Luben Tuikov03aba2f2006-06-23 09:39:09 -0700925 /* If the device is in the process of becoming
James Bottomleyf3e93f72006-04-25 16:48:30 -0500926 * ready, or has a temporary blockage, retry.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700927 */
James Bottomleyf3e93f72006-04-25 16:48:30 -0500928 if (sshdr.asc == 0x04) {
929 switch (sshdr.ascq) {
930 case 0x01: /* becoming ready */
931 case 0x04: /* format in progress */
932 case 0x05: /* rebuild in progress */
933 case 0x06: /* recalculation in progress */
934 case 0x07: /* operation in progress */
935 case 0x08: /* Long write in progress */
936 case 0x09: /* self test in progress */
937 scsi_requeue_command(q, cmd);
938 return;
939 default:
940 break;
941 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700942 }
Jens Axboe4aff5e22006-08-10 08:44:47 +0200943 if (!(req->cmd_flags & REQ_QUIET)) {
Jeff Garzik3bf743e2005-10-24 18:04:06 -0400944 scmd_printk(KERN_INFO, cmd,
Luben Tuikov03aba2f2006-06-23 09:39:09 -0700945 "Device not ready: ");
James Bottomleyf3e93f72006-04-25 16:48:30 -0500946 scsi_print_sense_hdr("", &sshdr);
947 }
James Bottomleye91442b2005-09-09 10:44:16 -0500948 scsi_end_request(cmd, 0, this_count, 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700949 return;
950 case VOLUME_OVERFLOW:
Jens Axboe4aff5e22006-08-10 08:44:47 +0200951 if (!(req->cmd_flags & REQ_QUIET)) {
Jeff Garzik3bf743e2005-10-24 18:04:06 -0400952 scmd_printk(KERN_INFO, cmd,
Luben Tuikov03aba2f2006-06-23 09:39:09 -0700953 "Volume overflow, CDB: ");
Christoph Hellwig631c2282006-07-08 20:42:15 +0200954 __scsi_print_command(cmd->cmnd);
James Bottomley3173d8c2005-09-04 11:32:05 -0500955 scsi_print_sense("", cmd);
956 }
Luben Tuikov03aba2f2006-06-23 09:39:09 -0700957 /* See SSC3rXX or current. */
958 scsi_end_request(cmd, 0, this_count, 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700959 return;
960 default:
961 break;
962 }
Luben Tuikov03aba2f2006-06-23 09:39:09 -0700963 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700964 if (host_byte(result) == DID_RESET) {
Luben Tuikov03aba2f2006-06-23 09:39:09 -0700965 /* Third party bus reset or reset for error recovery
966 * reasons. Just retry the request and see what
967 * happens.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700968 */
969 scsi_requeue_command(q, cmd);
970 return;
971 }
972 if (result) {
Jens Axboe4aff5e22006-08-10 08:44:47 +0200973 if (!(req->cmd_flags & REQ_QUIET)) {
Jeff Garzik3bf743e2005-10-24 18:04:06 -0400974 scmd_printk(KERN_INFO, cmd,
Luben Tuikov03aba2f2006-06-23 09:39:09 -0700975 "SCSI error: return code = 0x%08x\n",
976 result);
James Bottomley3173d8c2005-09-04 11:32:05 -0500977 if (driver_byte(result) & DRIVER_SENSE)
978 scsi_print_sense("", cmd);
979 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700980 }
Luben Tuikov03aba2f2006-06-23 09:39:09 -0700981 scsi_end_request(cmd, 0, this_count, !result);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700982}
983EXPORT_SYMBOL(scsi_io_completion);
984
985/*
986 * Function: scsi_init_io()
987 *
988 * Purpose: SCSI I/O initialize function.
989 *
990 * Arguments: cmd - Command descriptor we wish to initialize
991 *
992 * Returns: 0 on success
993 * BLKPREP_DEFER if the failure is retryable
994 * BLKPREP_KILL if the failure is fatal
995 */
996static int scsi_init_io(struct scsi_cmnd *cmd)
997{
998 struct request *req = cmd->request;
999 struct scatterlist *sgpnt;
1000 int count;
1001
1002 /*
Christoph Hellwig3b003152006-11-04 20:10:55 +01001003 * We used to not use scatter-gather for single segment request,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001004 * but now we do (it makes highmem I/O easier to support without
1005 * kmapping pages)
1006 */
1007 cmd->use_sg = req->nr_phys_segments;
1008
1009 /*
Christoph Hellwig3b003152006-11-04 20:10:55 +01001010 * If sg table allocation fails, requeue request later.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001011 */
1012 sgpnt = scsi_alloc_sgtable(cmd, GFP_ATOMIC);
Alan Stern7c72ce82005-10-14 11:23:27 -04001013 if (unlikely(!sgpnt)) {
1014 scsi_unprep_request(req);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001015 return BLKPREP_DEFER;
Alan Stern7c72ce82005-10-14 11:23:27 -04001016 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001017
Christoph Hellwig3b003152006-11-04 20:10:55 +01001018 req->buffer = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001019 cmd->request_buffer = (char *) sgpnt;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001020 if (blk_pc_request(req))
1021 cmd->request_bufflen = req->data_len;
Christoph Hellwig3b003152006-11-04 20:10:55 +01001022 else
1023 cmd->request_bufflen = req->nr_sectors << 9;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001024
1025 /*
1026 * Next, walk the list, and fill in the addresses and sizes of
1027 * each segment.
1028 */
1029 count = blk_rq_map_sg(req->q, req, cmd->request_buffer);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001030 if (likely(count <= cmd->use_sg)) {
1031 cmd->use_sg = count;
Christoph Hellwig3b003152006-11-04 20:10:55 +01001032 return BLKPREP_OK;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001033 }
1034
1035 printk(KERN_ERR "Incorrect number of segments after building list\n");
1036 printk(KERN_ERR "counted %d, received %d\n", count, cmd->use_sg);
1037 printk(KERN_ERR "req nr_sec %lu, cur_nr_sec %u\n", req->nr_sectors,
1038 req->current_nr_sectors);
1039
1040 /* release the command and kill it */
1041 scsi_release_buffers(cmd);
1042 scsi_put_command(cmd);
1043 return BLKPREP_KILL;
1044}
1045
Linus Torvalds1da177e2005-04-16 15:20:36 -07001046static int scsi_issue_flush_fn(request_queue_t *q, struct gendisk *disk,
1047 sector_t *error_sector)
1048{
1049 struct scsi_device *sdev = q->queuedata;
1050 struct scsi_driver *drv;
1051
1052 if (sdev->sdev_state != SDEV_RUNNING)
1053 return -ENXIO;
1054
1055 drv = *(struct scsi_driver **) disk->private_data;
1056 if (drv->issue_flush)
1057 return drv->issue_flush(&sdev->sdev_gendev, error_sector);
1058
1059 return -EOPNOTSUPP;
1060}
1061
Christoph Hellwig3b003152006-11-04 20:10:55 +01001062static struct scsi_cmnd *scsi_get_cmd_from_req(struct scsi_device *sdev,
1063 struct request *req)
1064{
1065 struct scsi_cmnd *cmd;
1066
1067 if (!req->special) {
1068 cmd = scsi_get_command(sdev, GFP_ATOMIC);
1069 if (unlikely(!cmd))
1070 return NULL;
1071 req->special = cmd;
1072 } else {
1073 cmd = req->special;
1074 }
1075
1076 /* pull a tag out of the request if we have one */
1077 cmd->tag = req->tag;
1078 cmd->request = req;
1079
1080 return cmd;
1081}
1082
Christoph Hellwig776b23a2006-01-06 18:34:07 +01001083static void scsi_blk_pc_done(struct scsi_cmnd *cmd)
James Bottomleye537a362005-06-05 02:07:14 -05001084{
1085 BUG_ON(!blk_pc_request(cmd->request));
Mike Christie0d957162005-11-11 05:31:40 -06001086 /*
1087 * This will complete the whole command with uptodate=1 so
1088 * as far as the block layer is concerned the command completed
1089 * successfully. Since this is a REQ_BLOCK_PC command the
1090 * caller should check the request's errors value
1091 */
Christoph Hellwig631c2282006-07-08 20:42:15 +02001092 scsi_io_completion(cmd, cmd->request_bufflen);
James Bottomleye537a362005-06-05 02:07:14 -05001093}
1094
Christoph Hellwig3b003152006-11-04 20:10:55 +01001095static int scsi_setup_blk_pc_cmnd(struct scsi_device *sdev, struct request *req)
James Bottomley7b163182005-12-15 20:17:02 -06001096{
Christoph Hellwig3b003152006-11-04 20:10:55 +01001097 struct scsi_cmnd *cmd;
1098
1099 cmd = scsi_get_cmd_from_req(sdev, req);
1100 if (unlikely(!cmd))
1101 return BLKPREP_DEFER;
1102
1103 /*
1104 * BLOCK_PC requests may transfer data, in which case they must
1105 * a bio attached to them. Or they might contain a SCSI command
1106 * that does not transfer data, in which case they may optionally
1107 * submit a request without an attached bio.
1108 */
1109 if (req->bio) {
1110 int ret;
1111
1112 BUG_ON(!req->nr_phys_segments);
1113
1114 ret = scsi_init_io(cmd);
1115 if (unlikely(ret))
1116 return ret;
1117 } else {
1118 BUG_ON(req->data_len);
1119 BUG_ON(req->data);
1120
1121 cmd->request_bufflen = 0;
1122 cmd->request_buffer = NULL;
1123 cmd->use_sg = 0;
1124 req->buffer = NULL;
1125 }
James Bottomley7b163182005-12-15 20:17:02 -06001126
Alexey Dobriyan46c43db2006-10-08 15:55:55 +04001127 BUILD_BUG_ON(sizeof(req->cmd) > sizeof(cmd->cmnd));
James Bottomley7b163182005-12-15 20:17:02 -06001128 memcpy(cmd->cmnd, req->cmd, sizeof(cmd->cmnd));
1129 cmd->cmd_len = req->cmd_len;
1130 if (!req->data_len)
1131 cmd->sc_data_direction = DMA_NONE;
1132 else if (rq_data_dir(req) == WRITE)
1133 cmd->sc_data_direction = DMA_TO_DEVICE;
1134 else
1135 cmd->sc_data_direction = DMA_FROM_DEVICE;
1136
1137 cmd->transfersize = req->data_len;
1138 cmd->allowed = req->retries;
1139 cmd->timeout_per_command = req->timeout;
Christoph Hellwig776b23a2006-01-06 18:34:07 +01001140 cmd->done = scsi_blk_pc_done;
Christoph Hellwig3b003152006-11-04 20:10:55 +01001141 return BLKPREP_OK;
1142}
1143
1144/*
1145 * Setup a REQ_TYPE_FS command. These are simple read/write request
1146 * from filesystems that still need to be translated to SCSI CDBs from
1147 * the ULD.
1148 */
1149static int scsi_setup_fs_cmnd(struct scsi_device *sdev, struct request *req)
1150{
1151 struct scsi_cmnd *cmd;
1152 struct scsi_driver *drv;
1153 int ret;
1154
1155 /*
1156 * Filesystem requests must transfer data.
1157 */
1158 BUG_ON(!req->nr_phys_segments);
1159
1160 cmd = scsi_get_cmd_from_req(sdev, req);
1161 if (unlikely(!cmd))
1162 return BLKPREP_DEFER;
1163
1164 ret = scsi_init_io(cmd);
1165 if (unlikely(ret))
1166 return ret;
1167
1168 /*
1169 * Initialize the actual SCSI command for this request.
1170 */
1171 drv = *(struct scsi_driver **)req->rq_disk->private_data;
1172 if (unlikely(!drv->init_command(cmd))) {
1173 scsi_release_buffers(cmd);
1174 scsi_put_command(cmd);
1175 return BLKPREP_KILL;
1176 }
1177
1178 return BLKPREP_OK;
James Bottomley7b163182005-12-15 20:17:02 -06001179}
James Bottomley7b163182005-12-15 20:17:02 -06001180
Linus Torvalds1da177e2005-04-16 15:20:36 -07001181static int scsi_prep_fn(struct request_queue *q, struct request *req)
1182{
1183 struct scsi_device *sdev = q->queuedata;
Christoph Hellwig3b003152006-11-04 20:10:55 +01001184 int ret = BLKPREP_OK;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001185
1186 /*
Christoph Hellwig3b003152006-11-04 20:10:55 +01001187 * If the device is not in running state we will reject some
1188 * or all commands.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001189 */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001190 if (unlikely(sdev->sdev_state != SDEV_RUNNING)) {
Christoph Hellwig3b003152006-11-04 20:10:55 +01001191 switch (sdev->sdev_state) {
1192 case SDEV_OFFLINE:
1193 /*
1194 * If the device is offline we refuse to process any
1195 * commands. The device must be brought online
1196 * before trying any recovery commands.
1197 */
1198 sdev_printk(KERN_ERR, sdev,
1199 "rejecting I/O to offline device\n");
1200 ret = BLKPREP_KILL;
1201 break;
1202 case SDEV_DEL:
1203 /*
1204 * If the device is fully deleted, we refuse to
1205 * process any commands as well.
1206 */
James Bottomley9ccfc752005-10-02 11:45:08 -05001207 sdev_printk(KERN_ERR, sdev,
1208 "rejecting I/O to dead device\n");
Christoph Hellwig3b003152006-11-04 20:10:55 +01001209 ret = BLKPREP_KILL;
1210 break;
1211 case SDEV_QUIESCE:
1212 case SDEV_BLOCK:
1213 /*
1214 * If the devices is blocked we defer normal commands.
1215 */
1216 if (!(req->cmd_flags & REQ_PREEMPT))
1217 ret = BLKPREP_DEFER;
1218 break;
1219 default:
1220 /*
1221 * For any other not fully online state we only allow
1222 * special commands. In particular any user initiated
1223 * command is not allowed.
1224 */
1225 if (!(req->cmd_flags & REQ_PREEMPT))
1226 ret = BLKPREP_KILL;
1227 break;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001228 }
Christoph Hellwig3b003152006-11-04 20:10:55 +01001229
1230 if (ret != BLKPREP_OK)
1231 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001232 }
1233
Christoph Hellwig3b003152006-11-04 20:10:55 +01001234 switch (req->cmd_type) {
1235 case REQ_TYPE_BLOCK_PC:
1236 ret = scsi_setup_blk_pc_cmnd(sdev, req);
1237 break;
1238 case REQ_TYPE_FS:
1239 ret = scsi_setup_fs_cmnd(sdev, req);
1240 break;
1241 default:
Linus Torvalds1da177e2005-04-16 15:20:36 -07001242 /*
Christoph Hellwig3b003152006-11-04 20:10:55 +01001243 * All other command types are not supported.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001244 *
Christoph Hellwig3b003152006-11-04 20:10:55 +01001245 * Note that these days the SCSI subsystem does not use
1246 * REQ_TYPE_SPECIAL requests anymore. These are only used
1247 * (directly or via blk_insert_request) by non-SCSI drivers.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001248 */
Christoph Hellwig3b003152006-11-04 20:10:55 +01001249 blk_dump_rq_flags(req, "SCSI bad req");
1250 ret = BLKPREP_KILL;
1251 break;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001252 }
1253
Christoph Hellwig3b003152006-11-04 20:10:55 +01001254 out:
1255 switch (ret) {
1256 case BLKPREP_KILL:
1257 req->errors = DID_NO_CONNECT << 16;
1258 break;
1259 case BLKPREP_DEFER:
1260 /*
1261 * If we defer, the elv_next_request() returns NULL, but the
1262 * queue must be restarted, so we plug here if no returning
1263 * command will automatically do that.
1264 */
1265 if (sdev->device_busy == 0)
1266 blk_plug_device(q);
1267 break;
1268 default:
1269 req->cmd_flags |= REQ_DONTPREP;
1270 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001271
Christoph Hellwig3b003152006-11-04 20:10:55 +01001272 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001273}
1274
1275/*
1276 * scsi_dev_queue_ready: if we can send requests to sdev, return 1 else
1277 * return 0.
1278 *
1279 * Called with the queue_lock held.
1280 */
1281static inline int scsi_dev_queue_ready(struct request_queue *q,
1282 struct scsi_device *sdev)
1283{
1284 if (sdev->device_busy >= sdev->queue_depth)
1285 return 0;
1286 if (sdev->device_busy == 0 && sdev->device_blocked) {
1287 /*
1288 * unblock after device_blocked iterates to zero
1289 */
1290 if (--sdev->device_blocked == 0) {
1291 SCSI_LOG_MLQUEUE(3,
James Bottomley9ccfc752005-10-02 11:45:08 -05001292 sdev_printk(KERN_INFO, sdev,
1293 "unblocking device at zero depth\n"));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001294 } else {
1295 blk_plug_device(q);
1296 return 0;
1297 }
1298 }
1299 if (sdev->device_blocked)
1300 return 0;
1301
1302 return 1;
1303}
1304
1305/*
1306 * scsi_host_queue_ready: if we can send requests to shost, return 1 else
1307 * return 0. We must end up running the queue again whenever 0 is
1308 * returned, else IO can hang.
1309 *
1310 * Called with host_lock held.
1311 */
1312static inline int scsi_host_queue_ready(struct request_queue *q,
1313 struct Scsi_Host *shost,
1314 struct scsi_device *sdev)
1315{
James Bottomley939647e2005-09-18 15:05:20 -05001316 if (scsi_host_in_recovery(shost))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001317 return 0;
1318 if (shost->host_busy == 0 && shost->host_blocked) {
1319 /*
1320 * unblock after host_blocked iterates to zero
1321 */
1322 if (--shost->host_blocked == 0) {
1323 SCSI_LOG_MLQUEUE(3,
1324 printk("scsi%d unblocking host at zero depth\n",
1325 shost->host_no));
1326 } else {
1327 blk_plug_device(q);
1328 return 0;
1329 }
1330 }
1331 if ((shost->can_queue > 0 && shost->host_busy >= shost->can_queue) ||
1332 shost->host_blocked || shost->host_self_blocked) {
1333 if (list_empty(&sdev->starved_entry))
1334 list_add_tail(&sdev->starved_entry, &shost->starved_list);
1335 return 0;
1336 }
1337
1338 /* We're OK to process the command, so we can't be starved */
1339 if (!list_empty(&sdev->starved_entry))
1340 list_del_init(&sdev->starved_entry);
1341
1342 return 1;
1343}
1344
1345/*
James Bottomleye91442b2005-09-09 10:44:16 -05001346 * Kill a request for a dead device
Linus Torvalds1da177e2005-04-16 15:20:36 -07001347 */
James Bottomleye91442b2005-09-09 10:44:16 -05001348static void scsi_kill_request(struct request *req, request_queue_t *q)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001349{
James Bottomleye91442b2005-09-09 10:44:16 -05001350 struct scsi_cmnd *cmd = req->special;
Tejun Heoe36e0c82006-04-11 17:27:53 +09001351 struct scsi_device *sdev = cmd->device;
1352 struct Scsi_Host *shost = sdev->host;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001353
James Bottomley788ce432005-09-09 13:40:23 -05001354 blkdev_dequeue_request(req);
1355
James Bottomleye91442b2005-09-09 10:44:16 -05001356 if (unlikely(cmd == NULL)) {
1357 printk(KERN_CRIT "impossible request in %s.\n",
1358 __FUNCTION__);
1359 BUG();
Linus Torvalds1da177e2005-04-16 15:20:36 -07001360 }
James Bottomleye91442b2005-09-09 10:44:16 -05001361
1362 scsi_init_cmd_errh(cmd);
1363 cmd->result = DID_NO_CONNECT << 16;
1364 atomic_inc(&cmd->device->iorequest_cnt);
Tejun Heoe36e0c82006-04-11 17:27:53 +09001365
1366 /*
1367 * SCSI request completion path will do scsi_device_unbusy(),
1368 * bump busy counts. To bump the counters, we need to dance
1369 * with the locks as normal issue path does.
1370 */
1371 sdev->device_busy++;
1372 spin_unlock(sdev->request_queue->queue_lock);
1373 spin_lock(shost->host_lock);
1374 shost->host_busy++;
1375 spin_unlock(shost->host_lock);
1376 spin_lock(sdev->request_queue->queue_lock);
1377
James Bottomleye91442b2005-09-09 10:44:16 -05001378 __scsi_done(cmd);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001379}
1380
Jens Axboe1aea6432006-01-09 16:03:03 +01001381static void scsi_softirq_done(struct request *rq)
1382{
1383 struct scsi_cmnd *cmd = rq->completion_data;
Brian King8884efa2006-02-24 17:10:04 -06001384 unsigned long wait_for = (cmd->allowed + 1) * cmd->timeout_per_command;
Jens Axboe1aea6432006-01-09 16:03:03 +01001385 int disposition;
1386
1387 INIT_LIST_HEAD(&cmd->eh_entry);
1388
1389 disposition = scsi_decide_disposition(cmd);
1390 if (disposition != SUCCESS &&
1391 time_before(cmd->jiffies_at_alloc + wait_for, jiffies)) {
1392 sdev_printk(KERN_ERR, cmd->device,
1393 "timing out command, waited %lus\n",
1394 wait_for/HZ);
1395 disposition = SUCCESS;
1396 }
1397
1398 scsi_log_completion(cmd, disposition);
1399
1400 switch (disposition) {
1401 case SUCCESS:
1402 scsi_finish_command(cmd);
1403 break;
1404 case NEEDS_RETRY:
1405 scsi_retry_command(cmd);
1406 break;
1407 case ADD_TO_MLQUEUE:
1408 scsi_queue_insert(cmd, SCSI_MLQUEUE_DEVICE_BUSY);
1409 break;
1410 default:
1411 if (!scsi_eh_scmd_add(cmd, 0))
1412 scsi_finish_command(cmd);
1413 }
1414}
1415
Linus Torvalds1da177e2005-04-16 15:20:36 -07001416/*
1417 * Function: scsi_request_fn()
1418 *
1419 * Purpose: Main strategy routine for SCSI.
1420 *
1421 * Arguments: q - Pointer to actual queue.
1422 *
1423 * Returns: Nothing
1424 *
1425 * Lock status: IO request lock assumed to be held when called.
1426 */
1427static void scsi_request_fn(struct request_queue *q)
1428{
1429 struct scsi_device *sdev = q->queuedata;
1430 struct Scsi_Host *shost;
1431 struct scsi_cmnd *cmd;
1432 struct request *req;
1433
1434 if (!sdev) {
1435 printk("scsi: killing requests for dead queue\n");
James Bottomleye91442b2005-09-09 10:44:16 -05001436 while ((req = elv_next_request(q)) != NULL)
1437 scsi_kill_request(req, q);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001438 return;
1439 }
1440
1441 if(!get_device(&sdev->sdev_gendev))
1442 /* We must be tearing the block queue down already */
1443 return;
1444
1445 /*
1446 * To start with, we keep looping until the queue is empty, or until
1447 * the host is no longer able to accept any more requests.
1448 */
1449 shost = sdev->host;
1450 while (!blk_queue_plugged(q)) {
1451 int rtn;
1452 /*
1453 * get next queueable request. We do this early to make sure
1454 * that the request is fully prepared even if we cannot
1455 * accept it.
1456 */
1457 req = elv_next_request(q);
1458 if (!req || !scsi_dev_queue_ready(q, sdev))
1459 break;
1460
1461 if (unlikely(!scsi_device_online(sdev))) {
James Bottomley9ccfc752005-10-02 11:45:08 -05001462 sdev_printk(KERN_ERR, sdev,
1463 "rejecting I/O to offline device\n");
James Bottomleye91442b2005-09-09 10:44:16 -05001464 scsi_kill_request(req, q);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001465 continue;
1466 }
1467
1468
1469 /*
1470 * Remove the request from the request list.
1471 */
1472 if (!(blk_queue_tagged(q) && !blk_queue_start_tag(q, req)))
1473 blkdev_dequeue_request(req);
1474 sdev->device_busy++;
1475
1476 spin_unlock(q->queue_lock);
James Bottomleye91442b2005-09-09 10:44:16 -05001477 cmd = req->special;
1478 if (unlikely(cmd == NULL)) {
1479 printk(KERN_CRIT "impossible request in %s.\n"
1480 "please mail a stack trace to "
Jens Axboe4aff5e22006-08-10 08:44:47 +02001481 "linux-scsi@vger.kernel.org\n",
James Bottomleye91442b2005-09-09 10:44:16 -05001482 __FUNCTION__);
Jens Axboe4aff5e22006-08-10 08:44:47 +02001483 blk_dump_rq_flags(req, "foo");
James Bottomleye91442b2005-09-09 10:44:16 -05001484 BUG();
1485 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001486 spin_lock(shost->host_lock);
1487
1488 if (!scsi_host_queue_ready(q, shost, sdev))
1489 goto not_ready;
1490 if (sdev->single_lun) {
1491 if (scsi_target(sdev)->starget_sdev_user &&
1492 scsi_target(sdev)->starget_sdev_user != sdev)
1493 goto not_ready;
1494 scsi_target(sdev)->starget_sdev_user = sdev;
1495 }
1496 shost->host_busy++;
1497
1498 /*
1499 * XXX(hch): This is rather suboptimal, scsi_dispatch_cmd will
1500 * take the lock again.
1501 */
1502 spin_unlock_irq(shost->host_lock);
1503
Linus Torvalds1da177e2005-04-16 15:20:36 -07001504 /*
1505 * Finally, initialize any error handling parameters, and set up
1506 * the timers for timeouts.
1507 */
1508 scsi_init_cmd_errh(cmd);
1509
1510 /*
1511 * Dispatch the command to the low-level driver.
1512 */
1513 rtn = scsi_dispatch_cmd(cmd);
1514 spin_lock_irq(q->queue_lock);
1515 if(rtn) {
1516 /* we're refusing the command; because of
1517 * the way locks get dropped, we need to
1518 * check here if plugging is required */
1519 if(sdev->device_busy == 0)
1520 blk_plug_device(q);
1521
1522 break;
1523 }
1524 }
1525
1526 goto out;
1527
1528 not_ready:
1529 spin_unlock_irq(shost->host_lock);
1530
1531 /*
1532 * lock q, handle tag, requeue req, and decrement device_busy. We
1533 * must return with queue_lock held.
1534 *
1535 * Decrementing device_busy without checking it is OK, as all such
1536 * cases (host limits or settings) should run the queue at some
1537 * later time.
1538 */
1539 spin_lock_irq(q->queue_lock);
1540 blk_requeue_request(q, req);
1541 sdev->device_busy--;
1542 if(sdev->device_busy == 0)
1543 blk_plug_device(q);
1544 out:
1545 /* must be careful here...if we trigger the ->remove() function
1546 * we cannot be holding the q lock */
1547 spin_unlock_irq(q->queue_lock);
1548 put_device(&sdev->sdev_gendev);
1549 spin_lock_irq(q->queue_lock);
1550}
1551
1552u64 scsi_calculate_bounce_limit(struct Scsi_Host *shost)
1553{
1554 struct device *host_dev;
1555 u64 bounce_limit = 0xffffffff;
1556
1557 if (shost->unchecked_isa_dma)
1558 return BLK_BOUNCE_ISA;
1559 /*
1560 * Platforms with virtual-DMA translation
1561 * hardware have no practical limit.
1562 */
1563 if (!PCI_DMA_BUS_IS_PHYS)
1564 return BLK_BOUNCE_ANY;
1565
1566 host_dev = scsi_get_device(shost);
1567 if (host_dev && host_dev->dma_mask)
1568 bounce_limit = *host_dev->dma_mask;
1569
1570 return bounce_limit;
1571}
1572EXPORT_SYMBOL(scsi_calculate_bounce_limit);
1573
FUJITA Tomonorib58d9152006-11-16 19:24:10 +09001574struct request_queue *__scsi_alloc_queue(struct Scsi_Host *shost,
1575 request_fn_proc *request_fn)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001576{
Linus Torvalds1da177e2005-04-16 15:20:36 -07001577 struct request_queue *q;
1578
FUJITA Tomonorib58d9152006-11-16 19:24:10 +09001579 q = blk_init_queue(request_fn, NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001580 if (!q)
1581 return NULL;
1582
Linus Torvalds1da177e2005-04-16 15:20:36 -07001583 blk_queue_max_hw_segments(q, shost->sg_tablesize);
1584 blk_queue_max_phys_segments(q, SCSI_MAX_PHYS_SEGMENTS);
1585 blk_queue_max_sectors(q, shost->max_sectors);
1586 blk_queue_bounce_limit(q, scsi_calculate_bounce_limit(shost));
1587 blk_queue_segment_boundary(q, shost->dma_boundary);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001588
Linus Torvalds1da177e2005-04-16 15:20:36 -07001589 if (!shost->use_clustering)
1590 clear_bit(QUEUE_FLAG_CLUSTER, &q->queue_flags);
1591 return q;
1592}
FUJITA Tomonorib58d9152006-11-16 19:24:10 +09001593EXPORT_SYMBOL(__scsi_alloc_queue);
1594
1595struct request_queue *scsi_alloc_queue(struct scsi_device *sdev)
1596{
1597 struct request_queue *q;
1598
1599 q = __scsi_alloc_queue(sdev->host, scsi_request_fn);
1600 if (!q)
1601 return NULL;
1602
1603 blk_queue_prep_rq(q, scsi_prep_fn);
1604 blk_queue_issue_flush_fn(q, scsi_issue_flush_fn);
1605 blk_queue_softirq_done(q, scsi_softirq_done);
1606 return q;
1607}
Linus Torvalds1da177e2005-04-16 15:20:36 -07001608
1609void scsi_free_queue(struct request_queue *q)
1610{
1611 blk_cleanup_queue(q);
1612}
1613
1614/*
1615 * Function: scsi_block_requests()
1616 *
1617 * Purpose: Utility function used by low-level drivers to prevent further
1618 * commands from being queued to the device.
1619 *
1620 * Arguments: shost - Host in question
1621 *
1622 * Returns: Nothing
1623 *
1624 * Lock status: No locks are assumed held.
1625 *
1626 * Notes: There is no timer nor any other means by which the requests
1627 * get unblocked other than the low-level driver calling
1628 * scsi_unblock_requests().
1629 */
1630void scsi_block_requests(struct Scsi_Host *shost)
1631{
1632 shost->host_self_blocked = 1;
1633}
1634EXPORT_SYMBOL(scsi_block_requests);
1635
1636/*
1637 * Function: scsi_unblock_requests()
1638 *
1639 * Purpose: Utility function used by low-level drivers to allow further
1640 * commands from being queued to the device.
1641 *
1642 * Arguments: shost - Host in question
1643 *
1644 * Returns: Nothing
1645 *
1646 * Lock status: No locks are assumed held.
1647 *
1648 * Notes: There is no timer nor any other means by which the requests
1649 * get unblocked other than the low-level driver calling
1650 * scsi_unblock_requests().
1651 *
1652 * This is done as an API function so that changes to the
1653 * internals of the scsi mid-layer won't require wholesale
1654 * changes to drivers that use this feature.
1655 */
1656void scsi_unblock_requests(struct Scsi_Host *shost)
1657{
1658 shost->host_self_blocked = 0;
1659 scsi_run_host_queues(shost);
1660}
1661EXPORT_SYMBOL(scsi_unblock_requests);
1662
1663int __init scsi_init_queue(void)
1664{
1665 int i;
1666
Mike Christieaa7b5cd2005-11-11 05:31:41 -06001667 scsi_io_context_cache = kmem_cache_create("scsi_io_context",
1668 sizeof(struct scsi_io_context),
1669 0, 0, NULL, NULL);
1670 if (!scsi_io_context_cache) {
1671 printk(KERN_ERR "SCSI: can't init scsi io context cache\n");
1672 return -ENOMEM;
1673 }
1674
Linus Torvalds1da177e2005-04-16 15:20:36 -07001675 for (i = 0; i < SG_MEMPOOL_NR; i++) {
1676 struct scsi_host_sg_pool *sgp = scsi_sg_pools + i;
1677 int size = sgp->size * sizeof(struct scatterlist);
1678
1679 sgp->slab = kmem_cache_create(sgp->name, size, 0,
1680 SLAB_HWCACHE_ALIGN, NULL, NULL);
1681 if (!sgp->slab) {
1682 printk(KERN_ERR "SCSI: can't init sg slab %s\n",
1683 sgp->name);
1684 }
1685
Matthew Dobson93d23412006-03-26 01:37:50 -08001686 sgp->pool = mempool_create_slab_pool(SG_MEMPOOL_SIZE,
1687 sgp->slab);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001688 if (!sgp->pool) {
1689 printk(KERN_ERR "SCSI: can't init sg mempool %s\n",
1690 sgp->name);
1691 }
1692 }
1693
1694 return 0;
1695}
1696
1697void scsi_exit_queue(void)
1698{
1699 int i;
1700
Mike Christieaa7b5cd2005-11-11 05:31:41 -06001701 kmem_cache_destroy(scsi_io_context_cache);
1702
Linus Torvalds1da177e2005-04-16 15:20:36 -07001703 for (i = 0; i < SG_MEMPOOL_NR; i++) {
1704 struct scsi_host_sg_pool *sgp = scsi_sg_pools + i;
1705 mempool_destroy(sgp->pool);
1706 kmem_cache_destroy(sgp->slab);
1707 }
1708}
James Bottomley5baba832006-03-18 14:10:35 -06001709
1710/**
1711 * scsi_mode_select - issue a mode select
1712 * @sdev: SCSI device to be queried
1713 * @pf: Page format bit (1 == standard, 0 == vendor specific)
1714 * @sp: Save page bit (0 == don't save, 1 == save)
1715 * @modepage: mode page being requested
1716 * @buffer: request buffer (may not be smaller than eight bytes)
1717 * @len: length of request buffer.
1718 * @timeout: command timeout
1719 * @retries: number of retries before failing
1720 * @data: returns a structure abstracting the mode header data
1721 * @sense: place to put sense data (or NULL if no sense to be collected).
1722 * must be SCSI_SENSE_BUFFERSIZE big.
1723 *
1724 * Returns zero if successful; negative error number or scsi
1725 * status on error
1726 *
1727 */
1728int
1729scsi_mode_select(struct scsi_device *sdev, int pf, int sp, int modepage,
1730 unsigned char *buffer, int len, int timeout, int retries,
1731 struct scsi_mode_data *data, struct scsi_sense_hdr *sshdr)
1732{
1733 unsigned char cmd[10];
1734 unsigned char *real_buffer;
1735 int ret;
1736
1737 memset(cmd, 0, sizeof(cmd));
1738 cmd[1] = (pf ? 0x10 : 0) | (sp ? 0x01 : 0);
1739
1740 if (sdev->use_10_for_ms) {
1741 if (len > 65535)
1742 return -EINVAL;
1743 real_buffer = kmalloc(8 + len, GFP_KERNEL);
1744 if (!real_buffer)
1745 return -ENOMEM;
1746 memcpy(real_buffer + 8, buffer, len);
1747 len += 8;
1748 real_buffer[0] = 0;
1749 real_buffer[1] = 0;
1750 real_buffer[2] = data->medium_type;
1751 real_buffer[3] = data->device_specific;
1752 real_buffer[4] = data->longlba ? 0x01 : 0;
1753 real_buffer[5] = 0;
1754 real_buffer[6] = data->block_descriptor_length >> 8;
1755 real_buffer[7] = data->block_descriptor_length;
1756
1757 cmd[0] = MODE_SELECT_10;
1758 cmd[7] = len >> 8;
1759 cmd[8] = len;
1760 } else {
1761 if (len > 255 || data->block_descriptor_length > 255 ||
1762 data->longlba)
1763 return -EINVAL;
1764
1765 real_buffer = kmalloc(4 + len, GFP_KERNEL);
1766 if (!real_buffer)
1767 return -ENOMEM;
1768 memcpy(real_buffer + 4, buffer, len);
1769 len += 4;
1770 real_buffer[0] = 0;
1771 real_buffer[1] = data->medium_type;
1772 real_buffer[2] = data->device_specific;
1773 real_buffer[3] = data->block_descriptor_length;
1774
1775
1776 cmd[0] = MODE_SELECT;
1777 cmd[4] = len;
1778 }
1779
1780 ret = scsi_execute_req(sdev, cmd, DMA_TO_DEVICE, real_buffer, len,
1781 sshdr, timeout, retries);
1782 kfree(real_buffer);
1783 return ret;
1784}
1785EXPORT_SYMBOL_GPL(scsi_mode_select);
1786
Linus Torvalds1da177e2005-04-16 15:20:36 -07001787/**
James Bottomleyea73a9f2005-08-28 11:33:52 -05001788 * scsi_mode_sense - issue a mode sense, falling back from 10 to
Linus Torvalds1da177e2005-04-16 15:20:36 -07001789 * six bytes if necessary.
James Bottomley1cf72692005-08-28 11:27:01 -05001790 * @sdev: SCSI device to be queried
Linus Torvalds1da177e2005-04-16 15:20:36 -07001791 * @dbd: set if mode sense will allow block descriptors to be returned
1792 * @modepage: mode page being requested
1793 * @buffer: request buffer (may not be smaller than eight bytes)
1794 * @len: length of request buffer.
1795 * @timeout: command timeout
1796 * @retries: number of retries before failing
1797 * @data: returns a structure abstracting the mode header data
James Bottomley1cf72692005-08-28 11:27:01 -05001798 * @sense: place to put sense data (or NULL if no sense to be collected).
1799 * must be SCSI_SENSE_BUFFERSIZE big.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001800 *
1801 * Returns zero if unsuccessful, or the header offset (either 4
1802 * or 8 depending on whether a six or ten byte command was
1803 * issued) if successful.
1804 **/
1805int
James Bottomley1cf72692005-08-28 11:27:01 -05001806scsi_mode_sense(struct scsi_device *sdev, int dbd, int modepage,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001807 unsigned char *buffer, int len, int timeout, int retries,
James Bottomley5baba832006-03-18 14:10:35 -06001808 struct scsi_mode_data *data, struct scsi_sense_hdr *sshdr)
1809{
Linus Torvalds1da177e2005-04-16 15:20:36 -07001810 unsigned char cmd[12];
1811 int use_10_for_ms;
1812 int header_length;
James Bottomley1cf72692005-08-28 11:27:01 -05001813 int result;
James Bottomleyea73a9f2005-08-28 11:33:52 -05001814 struct scsi_sense_hdr my_sshdr;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001815
1816 memset(data, 0, sizeof(*data));
1817 memset(&cmd[0], 0, 12);
1818 cmd[1] = dbd & 0x18; /* allows DBD and LLBA bits */
1819 cmd[2] = modepage;
1820
James Bottomleyea73a9f2005-08-28 11:33:52 -05001821 /* caller might not be interested in sense, but we need it */
1822 if (!sshdr)
1823 sshdr = &my_sshdr;
1824
Linus Torvalds1da177e2005-04-16 15:20:36 -07001825 retry:
James Bottomley1cf72692005-08-28 11:27:01 -05001826 use_10_for_ms = sdev->use_10_for_ms;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001827
1828 if (use_10_for_ms) {
1829 if (len < 8)
1830 len = 8;
1831
1832 cmd[0] = MODE_SENSE_10;
1833 cmd[8] = len;
1834 header_length = 8;
1835 } else {
1836 if (len < 4)
1837 len = 4;
1838
1839 cmd[0] = MODE_SENSE;
1840 cmd[4] = len;
1841 header_length = 4;
1842 }
1843
Linus Torvalds1da177e2005-04-16 15:20:36 -07001844 memset(buffer, 0, len);
1845
James Bottomley1cf72692005-08-28 11:27:01 -05001846 result = scsi_execute_req(sdev, cmd, DMA_FROM_DEVICE, buffer, len,
James Bottomleyea73a9f2005-08-28 11:33:52 -05001847 sshdr, timeout, retries);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001848
1849 /* This code looks awful: what it's doing is making sure an
1850 * ILLEGAL REQUEST sense return identifies the actual command
1851 * byte as the problem. MODE_SENSE commands can return
1852 * ILLEGAL REQUEST if the code page isn't supported */
1853
James Bottomley1cf72692005-08-28 11:27:01 -05001854 if (use_10_for_ms && !scsi_status_is_good(result) &&
1855 (driver_byte(result) & DRIVER_SENSE)) {
James Bottomleyea73a9f2005-08-28 11:33:52 -05001856 if (scsi_sense_valid(sshdr)) {
1857 if ((sshdr->sense_key == ILLEGAL_REQUEST) &&
1858 (sshdr->asc == 0x20) && (sshdr->ascq == 0)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001859 /*
1860 * Invalid command operation code
1861 */
James Bottomley1cf72692005-08-28 11:27:01 -05001862 sdev->use_10_for_ms = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001863 goto retry;
1864 }
1865 }
1866 }
1867
James Bottomley1cf72692005-08-28 11:27:01 -05001868 if(scsi_status_is_good(result)) {
Al Viro6d73c852006-02-23 02:03:16 +01001869 if (unlikely(buffer[0] == 0x86 && buffer[1] == 0x0b &&
1870 (modepage == 6 || modepage == 8))) {
1871 /* Initio breakage? */
1872 header_length = 0;
1873 data->length = 13;
1874 data->medium_type = 0;
1875 data->device_specific = 0;
1876 data->longlba = 0;
1877 data->block_descriptor_length = 0;
1878 } else if(use_10_for_ms) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001879 data->length = buffer[0]*256 + buffer[1] + 2;
1880 data->medium_type = buffer[2];
1881 data->device_specific = buffer[3];
1882 data->longlba = buffer[4] & 0x01;
1883 data->block_descriptor_length = buffer[6]*256
1884 + buffer[7];
1885 } else {
1886 data->length = buffer[0] + 1;
1887 data->medium_type = buffer[1];
1888 data->device_specific = buffer[2];
1889 data->block_descriptor_length = buffer[3];
1890 }
Al Viro6d73c852006-02-23 02:03:16 +01001891 data->header_length = header_length;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001892 }
1893
James Bottomley1cf72692005-08-28 11:27:01 -05001894 return result;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001895}
1896EXPORT_SYMBOL(scsi_mode_sense);
1897
1898int
1899scsi_test_unit_ready(struct scsi_device *sdev, int timeout, int retries)
1900{
Linus Torvalds1da177e2005-04-16 15:20:36 -07001901 char cmd[] = {
1902 TEST_UNIT_READY, 0, 0, 0, 0, 0,
1903 };
James Bottomleyea73a9f2005-08-28 11:33:52 -05001904 struct scsi_sense_hdr sshdr;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001905 int result;
1906
James Bottomleyea73a9f2005-08-28 11:33:52 -05001907 result = scsi_execute_req(sdev, cmd, DMA_NONE, NULL, 0, &sshdr,
James Bottomley1cf72692005-08-28 11:27:01 -05001908 timeout, retries);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001909
James Bottomley1cf72692005-08-28 11:27:01 -05001910 if ((driver_byte(result) & DRIVER_SENSE) && sdev->removable) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001911
James Bottomleyea73a9f2005-08-28 11:33:52 -05001912 if ((scsi_sense_valid(&sshdr)) &&
Linus Torvalds1da177e2005-04-16 15:20:36 -07001913 ((sshdr.sense_key == UNIT_ATTENTION) ||
1914 (sshdr.sense_key == NOT_READY))) {
1915 sdev->changed = 1;
James Bottomley1cf72692005-08-28 11:27:01 -05001916 result = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001917 }
1918 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001919 return result;
1920}
1921EXPORT_SYMBOL(scsi_test_unit_ready);
1922
1923/**
1924 * scsi_device_set_state - Take the given device through the device
1925 * state model.
1926 * @sdev: scsi device to change the state of.
1927 * @state: state to change to.
1928 *
1929 * Returns zero if unsuccessful or an error if the requested
1930 * transition is illegal.
1931 **/
1932int
1933scsi_device_set_state(struct scsi_device *sdev, enum scsi_device_state state)
1934{
1935 enum scsi_device_state oldstate = sdev->sdev_state;
1936
1937 if (state == oldstate)
1938 return 0;
1939
1940 switch (state) {
1941 case SDEV_CREATED:
1942 /* There are no legal states that come back to
1943 * created. This is the manually initialised start
1944 * state */
1945 goto illegal;
1946
1947 case SDEV_RUNNING:
1948 switch (oldstate) {
1949 case SDEV_CREATED:
1950 case SDEV_OFFLINE:
1951 case SDEV_QUIESCE:
1952 case SDEV_BLOCK:
1953 break;
1954 default:
1955 goto illegal;
1956 }
1957 break;
1958
1959 case SDEV_QUIESCE:
1960 switch (oldstate) {
1961 case SDEV_RUNNING:
1962 case SDEV_OFFLINE:
1963 break;
1964 default:
1965 goto illegal;
1966 }
1967 break;
1968
1969 case SDEV_OFFLINE:
1970 switch (oldstate) {
1971 case SDEV_CREATED:
1972 case SDEV_RUNNING:
1973 case SDEV_QUIESCE:
1974 case SDEV_BLOCK:
1975 break;
1976 default:
1977 goto illegal;
1978 }
1979 break;
1980
1981 case SDEV_BLOCK:
1982 switch (oldstate) {
1983 case SDEV_CREATED:
1984 case SDEV_RUNNING:
1985 break;
1986 default:
1987 goto illegal;
1988 }
1989 break;
1990
1991 case SDEV_CANCEL:
1992 switch (oldstate) {
1993 case SDEV_CREATED:
1994 case SDEV_RUNNING:
Alan Stern9ea72902006-06-23 14:25:34 -04001995 case SDEV_QUIESCE:
Linus Torvalds1da177e2005-04-16 15:20:36 -07001996 case SDEV_OFFLINE:
1997 case SDEV_BLOCK:
1998 break;
1999 default:
2000 goto illegal;
2001 }
2002 break;
2003
2004 case SDEV_DEL:
2005 switch (oldstate) {
Brian King309bd272006-06-27 11:10:43 -05002006 case SDEV_CREATED:
2007 case SDEV_RUNNING:
2008 case SDEV_OFFLINE:
Linus Torvalds1da177e2005-04-16 15:20:36 -07002009 case SDEV_CANCEL:
2010 break;
2011 default:
2012 goto illegal;
2013 }
2014 break;
2015
2016 }
2017 sdev->sdev_state = state;
2018 return 0;
2019
2020 illegal:
2021 SCSI_LOG_ERROR_RECOVERY(1,
James Bottomley9ccfc752005-10-02 11:45:08 -05002022 sdev_printk(KERN_ERR, sdev,
2023 "Illegal state transition %s->%s\n",
2024 scsi_device_state_name(oldstate),
2025 scsi_device_state_name(state))
Linus Torvalds1da177e2005-04-16 15:20:36 -07002026 );
2027 return -EINVAL;
2028}
2029EXPORT_SYMBOL(scsi_device_set_state);
2030
2031/**
2032 * scsi_device_quiesce - Block user issued commands.
2033 * @sdev: scsi device to quiesce.
2034 *
2035 * This works by trying to transition to the SDEV_QUIESCE state
2036 * (which must be a legal transition). When the device is in this
2037 * state, only special requests will be accepted, all others will
2038 * be deferred. Since special requests may also be requeued requests,
2039 * a successful return doesn't guarantee the device will be
2040 * totally quiescent.
2041 *
2042 * Must be called with user context, may sleep.
2043 *
2044 * Returns zero if unsuccessful or an error if not.
2045 **/
2046int
2047scsi_device_quiesce(struct scsi_device *sdev)
2048{
2049 int err = scsi_device_set_state(sdev, SDEV_QUIESCE);
2050 if (err)
2051 return err;
2052
2053 scsi_run_queue(sdev->request_queue);
2054 while (sdev->device_busy) {
2055 msleep_interruptible(200);
2056 scsi_run_queue(sdev->request_queue);
2057 }
2058 return 0;
2059}
2060EXPORT_SYMBOL(scsi_device_quiesce);
2061
2062/**
2063 * scsi_device_resume - Restart user issued commands to a quiesced device.
2064 * @sdev: scsi device to resume.
2065 *
2066 * Moves the device from quiesced back to running and restarts the
2067 * queues.
2068 *
2069 * Must be called with user context, may sleep.
2070 **/
2071void
2072scsi_device_resume(struct scsi_device *sdev)
2073{
2074 if(scsi_device_set_state(sdev, SDEV_RUNNING))
2075 return;
2076 scsi_run_queue(sdev->request_queue);
2077}
2078EXPORT_SYMBOL(scsi_device_resume);
2079
2080static void
2081device_quiesce_fn(struct scsi_device *sdev, void *data)
2082{
2083 scsi_device_quiesce(sdev);
2084}
2085
2086void
2087scsi_target_quiesce(struct scsi_target *starget)
2088{
2089 starget_for_each_device(starget, NULL, device_quiesce_fn);
2090}
2091EXPORT_SYMBOL(scsi_target_quiesce);
2092
2093static void
2094device_resume_fn(struct scsi_device *sdev, void *data)
2095{
2096 scsi_device_resume(sdev);
2097}
2098
2099void
2100scsi_target_resume(struct scsi_target *starget)
2101{
2102 starget_for_each_device(starget, NULL, device_resume_fn);
2103}
2104EXPORT_SYMBOL(scsi_target_resume);
2105
2106/**
2107 * scsi_internal_device_block - internal function to put a device
2108 * temporarily into the SDEV_BLOCK state
2109 * @sdev: device to block
2110 *
2111 * Block request made by scsi lld's to temporarily stop all
2112 * scsi commands on the specified device. Called from interrupt
2113 * or normal process context.
2114 *
2115 * Returns zero if successful or error if not
2116 *
2117 * Notes:
2118 * This routine transitions the device to the SDEV_BLOCK state
2119 * (which must be a legal transition). When the device is in this
2120 * state, all commands are deferred until the scsi lld reenables
2121 * the device with scsi_device_unblock or device_block_tmo fires.
2122 * This routine assumes the host_lock is held on entry.
2123 **/
2124int
2125scsi_internal_device_block(struct scsi_device *sdev)
2126{
2127 request_queue_t *q = sdev->request_queue;
2128 unsigned long flags;
2129 int err = 0;
2130
2131 err = scsi_device_set_state(sdev, SDEV_BLOCK);
2132 if (err)
2133 return err;
2134
2135 /*
2136 * The device has transitioned to SDEV_BLOCK. Stop the
2137 * block layer from calling the midlayer with this device's
2138 * request queue.
2139 */
2140 spin_lock_irqsave(q->queue_lock, flags);
2141 blk_stop_queue(q);
2142 spin_unlock_irqrestore(q->queue_lock, flags);
2143
2144 return 0;
2145}
2146EXPORT_SYMBOL_GPL(scsi_internal_device_block);
2147
2148/**
2149 * scsi_internal_device_unblock - resume a device after a block request
2150 * @sdev: device to resume
2151 *
2152 * Called by scsi lld's or the midlayer to restart the device queue
2153 * for the previously suspended scsi device. Called from interrupt or
2154 * normal process context.
2155 *
2156 * Returns zero if successful or error if not.
2157 *
2158 * Notes:
2159 * This routine transitions the device to the SDEV_RUNNING state
2160 * (which must be a legal transition) allowing the midlayer to
2161 * goose the queue for this device. This routine assumes the
2162 * host_lock is held upon entry.
2163 **/
2164int
2165scsi_internal_device_unblock(struct scsi_device *sdev)
2166{
2167 request_queue_t *q = sdev->request_queue;
2168 int err;
2169 unsigned long flags;
2170
2171 /*
2172 * Try to transition the scsi device to SDEV_RUNNING
2173 * and goose the device queue if successful.
2174 */
2175 err = scsi_device_set_state(sdev, SDEV_RUNNING);
2176 if (err)
2177 return err;
2178
2179 spin_lock_irqsave(q->queue_lock, flags);
2180 blk_start_queue(q);
2181 spin_unlock_irqrestore(q->queue_lock, flags);
2182
2183 return 0;
2184}
2185EXPORT_SYMBOL_GPL(scsi_internal_device_unblock);
2186
2187static void
2188device_block(struct scsi_device *sdev, void *data)
2189{
2190 scsi_internal_device_block(sdev);
2191}
2192
2193static int
2194target_block(struct device *dev, void *data)
2195{
2196 if (scsi_is_target_device(dev))
2197 starget_for_each_device(to_scsi_target(dev), NULL,
2198 device_block);
2199 return 0;
2200}
2201
2202void
2203scsi_target_block(struct device *dev)
2204{
2205 if (scsi_is_target_device(dev))
2206 starget_for_each_device(to_scsi_target(dev), NULL,
2207 device_block);
2208 else
2209 device_for_each_child(dev, NULL, target_block);
2210}
2211EXPORT_SYMBOL_GPL(scsi_target_block);
2212
2213static void
2214device_unblock(struct scsi_device *sdev, void *data)
2215{
2216 scsi_internal_device_unblock(sdev);
2217}
2218
2219static int
2220target_unblock(struct device *dev, void *data)
2221{
2222 if (scsi_is_target_device(dev))
2223 starget_for_each_device(to_scsi_target(dev), NULL,
2224 device_unblock);
2225 return 0;
2226}
2227
2228void
2229scsi_target_unblock(struct device *dev)
2230{
2231 if (scsi_is_target_device(dev))
2232 starget_for_each_device(to_scsi_target(dev), NULL,
2233 device_unblock);
2234 else
2235 device_for_each_child(dev, NULL, target_unblock);
2236}
2237EXPORT_SYMBOL_GPL(scsi_target_unblock);
Guennadi Liakhovetskicdb8c2a2006-04-02 21:57:43 +02002238
2239/**
2240 * scsi_kmap_atomic_sg - find and atomically map an sg-elemnt
2241 * @sg: scatter-gather list
2242 * @sg_count: number of segments in sg
2243 * @offset: offset in bytes into sg, on return offset into the mapped area
2244 * @len: bytes to map, on return number of bytes mapped
2245 *
2246 * Returns virtual address of the start of the mapped page
2247 */
2248void *scsi_kmap_atomic_sg(struct scatterlist *sg, int sg_count,
2249 size_t *offset, size_t *len)
2250{
2251 int i;
2252 size_t sg_len = 0, len_complete = 0;
2253 struct page *page;
2254
2255 for (i = 0; i < sg_count; i++) {
2256 len_complete = sg_len; /* Complete sg-entries */
2257 sg_len += sg[i].length;
2258 if (sg_len > *offset)
2259 break;
2260 }
2261
2262 if (unlikely(i == sg_count)) {
Andrew Morton169e1a22006-04-18 21:09:08 -07002263 printk(KERN_ERR "%s: Bytes in sg: %zu, requested offset %zu, "
2264 "elements %d\n",
Guennadi Liakhovetskicdb8c2a2006-04-02 21:57:43 +02002265 __FUNCTION__, sg_len, *offset, sg_count);
2266 WARN_ON(1);
2267 return NULL;
2268 }
2269
2270 /* Offset starting from the beginning of first page in this sg-entry */
2271 *offset = *offset - len_complete + sg[i].offset;
2272
2273 /* Assumption: contiguous pages can be accessed as "page + i" */
2274 page = nth_page(sg[i].page, (*offset >> PAGE_SHIFT));
2275 *offset &= ~PAGE_MASK;
2276
2277 /* Bytes in this sg-entry from *offset to the end of the page */
2278 sg_len = PAGE_SIZE - *offset;
2279 if (*len > sg_len)
2280 *len = sg_len;
2281
2282 return kmap_atomic(page, KM_BIO_SRC_IRQ);
2283}
2284EXPORT_SYMBOL(scsi_kmap_atomic_sg);
2285
2286/**
2287 * scsi_kunmap_atomic_sg - atomically unmap a virtual address, previously
2288 * mapped with scsi_kmap_atomic_sg
2289 * @virt: virtual address to be unmapped
2290 */
2291void scsi_kunmap_atomic_sg(void *virt)
2292{
2293 kunmap_atomic(virt, KM_BIO_SRC_IRQ);
2294}
2295EXPORT_SYMBOL(scsi_kunmap_atomic_sg);