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86db1e29 | 1 | /* |
4fed947c | 2 | * Functions to sequence FLUSH and FUA writes. |
ae1b1539 TH |
3 | * |
4 | * Copyright (C) 2011 Max Planck Institute for Gravitational Physics | |
5 | * Copyright (C) 2011 Tejun Heo <tj@kernel.org> | |
6 | * | |
7 | * This file is released under the GPLv2. | |
8 | * | |
9 | * REQ_{FLUSH|FUA} requests are decomposed to sequences consisted of three | |
10 | * optional steps - PREFLUSH, DATA and POSTFLUSH - according to the request | |
11 | * properties and hardware capability. | |
12 | * | |
13 | * If a request doesn't have data, only REQ_FLUSH makes sense, which | |
14 | * indicates a simple flush request. If there is data, REQ_FLUSH indicates | |
15 | * that the device cache should be flushed before the data is executed, and | |
16 | * REQ_FUA means that the data must be on non-volatile media on request | |
17 | * completion. | |
18 | * | |
19 | * If the device doesn't have writeback cache, FLUSH and FUA don't make any | |
20 | * difference. The requests are either completed immediately if there's no | |
21 | * data or executed as normal requests otherwise. | |
22 | * | |
23 | * If the device has writeback cache and supports FUA, REQ_FLUSH is | |
24 | * translated to PREFLUSH but REQ_FUA is passed down directly with DATA. | |
25 | * | |
26 | * If the device has writeback cache and doesn't support FUA, REQ_FLUSH is | |
27 | * translated to PREFLUSH and REQ_FUA to POSTFLUSH. | |
28 | * | |
29 | * The actual execution of flush is double buffered. Whenever a request | |
30 | * needs to execute PRE or POSTFLUSH, it queues at | |
31 | * q->flush_queue[q->flush_pending_idx]. Once certain criteria are met, a | |
32 | * flush is issued and the pending_idx is toggled. When the flush | |
33 | * completes, all the requests which were pending are proceeded to the next | |
34 | * step. This allows arbitrary merging of different types of FLUSH/FUA | |
35 | * requests. | |
36 | * | |
37 | * Currently, the following conditions are used to determine when to issue | |
38 | * flush. | |
39 | * | |
40 | * C1. At any given time, only one flush shall be in progress. This makes | |
41 | * double buffering sufficient. | |
42 | * | |
43 | * C2. Flush is deferred if any request is executing DATA of its sequence. | |
44 | * This avoids issuing separate POSTFLUSHes for requests which shared | |
45 | * PREFLUSH. | |
46 | * | |
47 | * C3. The second condition is ignored if there is a request which has | |
48 | * waited longer than FLUSH_PENDING_TIMEOUT. This is to avoid | |
49 | * starvation in the unlikely case where there are continuous stream of | |
50 | * FUA (without FLUSH) requests. | |
51 | * | |
52 | * For devices which support FUA, it isn't clear whether C2 (and thus C3) | |
53 | * is beneficial. | |
54 | * | |
55 | * Note that a sequenced FLUSH/FUA request with DATA is completed twice. | |
56 | * Once while executing DATA and again after the whole sequence is | |
57 | * complete. The first completion updates the contained bio but doesn't | |
58 | * finish it so that the bio submitter is notified only after the whole | |
59 | * sequence is complete. This is implemented by testing REQ_FLUSH_SEQ in | |
60 | * req_bio_endio(). | |
61 | * | |
62 | * The above peculiarity requires that each FLUSH/FUA request has only one | |
63 | * bio attached to it, which is guaranteed as they aren't allowed to be | |
64 | * merged in the usual way. | |
86db1e29 | 65 | */ |
ae1b1539 | 66 | |
86db1e29 JA |
67 | #include <linux/kernel.h> |
68 | #include <linux/module.h> | |
69 | #include <linux/bio.h> | |
70 | #include <linux/blkdev.h> | |
5a0e3ad6 | 71 | #include <linux/gfp.h> |
320ae51f | 72 | #include <linux/blk-mq.h> |
86db1e29 JA |
73 | |
74 | #include "blk.h" | |
320ae51f | 75 | #include "blk-mq.h" |
86db1e29 | 76 | |
4fed947c TH |
77 | /* FLUSH/FUA sequences */ |
78 | enum { | |
ae1b1539 TH |
79 | REQ_FSEQ_PREFLUSH = (1 << 0), /* pre-flushing in progress */ |
80 | REQ_FSEQ_DATA = (1 << 1), /* data write in progress */ | |
81 | REQ_FSEQ_POSTFLUSH = (1 << 2), /* post-flushing in progress */ | |
82 | REQ_FSEQ_DONE = (1 << 3), | |
83 | ||
84 | REQ_FSEQ_ACTIONS = REQ_FSEQ_PREFLUSH | REQ_FSEQ_DATA | | |
85 | REQ_FSEQ_POSTFLUSH, | |
86 | ||
87 | /* | |
88 | * If flush has been pending longer than the following timeout, | |
89 | * it's issued even if flush_data requests are still in flight. | |
90 | */ | |
91 | FLUSH_PENDING_TIMEOUT = 5 * HZ, | |
4fed947c TH |
92 | }; |
93 | ||
ae1b1539 | 94 | static bool blk_kick_flush(struct request_queue *q); |
28e7d184 | 95 | |
ae1b1539 | 96 | static unsigned int blk_flush_policy(unsigned int fflags, struct request *rq) |
86db1e29 | 97 | { |
ae1b1539 | 98 | unsigned int policy = 0; |
86db1e29 | 99 | |
fa1bf42f JM |
100 | if (blk_rq_sectors(rq)) |
101 | policy |= REQ_FSEQ_DATA; | |
102 | ||
ae1b1539 TH |
103 | if (fflags & REQ_FLUSH) { |
104 | if (rq->cmd_flags & REQ_FLUSH) | |
105 | policy |= REQ_FSEQ_PREFLUSH; | |
ae1b1539 TH |
106 | if (!(fflags & REQ_FUA) && (rq->cmd_flags & REQ_FUA)) |
107 | policy |= REQ_FSEQ_POSTFLUSH; | |
28e7d184 | 108 | } |
ae1b1539 | 109 | return policy; |
86db1e29 JA |
110 | } |
111 | ||
ae1b1539 | 112 | static unsigned int blk_flush_cur_seq(struct request *rq) |
47f70d5a | 113 | { |
ae1b1539 TH |
114 | return 1 << ffz(rq->flush.seq); |
115 | } | |
47f70d5a | 116 | |
ae1b1539 TH |
117 | static void blk_flush_restore_request(struct request *rq) |
118 | { | |
47f70d5a | 119 | /* |
ae1b1539 TH |
120 | * After flush data completion, @rq->bio is %NULL but we need to |
121 | * complete the bio again. @rq->biotail is guaranteed to equal the | |
122 | * original @rq->bio. Restore it. | |
47f70d5a | 123 | */ |
ae1b1539 TH |
124 | rq->bio = rq->biotail; |
125 | ||
126 | /* make @rq a normal request */ | |
127 | rq->cmd_flags &= ~REQ_FLUSH_SEQ; | |
4853abaa | 128 | rq->end_io = rq->flush.saved_end_io; |
320ae51f JA |
129 | |
130 | blk_clear_rq_complete(rq); | |
131 | } | |
132 | ||
18741986 | 133 | static void mq_flush_run(struct work_struct *work) |
320ae51f JA |
134 | { |
135 | struct request *rq; | |
136 | ||
18741986 | 137 | rq = container_of(work, struct request, mq_flush_work); |
320ae51f JA |
138 | |
139 | memset(&rq->csd, 0, sizeof(rq->csd)); | |
feb71dae | 140 | blk_mq_insert_request(rq, false, true, false); |
320ae51f JA |
141 | } |
142 | ||
10beafc1 | 143 | static bool blk_flush_queue_rq(struct request *rq, bool add_front) |
320ae51f | 144 | { |
18741986 CH |
145 | if (rq->q->mq_ops) { |
146 | INIT_WORK(&rq->mq_flush_work, mq_flush_run); | |
147 | kblockd_schedule_work(rq->q, &rq->mq_flush_work); | |
148 | return false; | |
149 | } else { | |
10beafc1 MS |
150 | if (add_front) |
151 | list_add(&rq->queuelist, &rq->q->queue_head); | |
152 | else | |
153 | list_add_tail(&rq->queuelist, &rq->q->queue_head); | |
18741986 CH |
154 | return true; |
155 | } | |
47f70d5a TH |
156 | } |
157 | ||
ae1b1539 TH |
158 | /** |
159 | * blk_flush_complete_seq - complete flush sequence | |
160 | * @rq: FLUSH/FUA request being sequenced | |
161 | * @seq: sequences to complete (mask of %REQ_FSEQ_*, can be zero) | |
162 | * @error: whether an error occurred | |
163 | * | |
164 | * @rq just completed @seq part of its flush sequence, record the | |
165 | * completion and trigger the next step. | |
166 | * | |
167 | * CONTEXT: | |
320ae51f | 168 | * spin_lock_irq(q->queue_lock or q->mq_flush_lock) |
ae1b1539 TH |
169 | * |
170 | * RETURNS: | |
171 | * %true if requests were added to the dispatch queue, %false otherwise. | |
172 | */ | |
173 | static bool blk_flush_complete_seq(struct request *rq, unsigned int seq, | |
174 | int error) | |
86db1e29 | 175 | { |
ae1b1539 TH |
176 | struct request_queue *q = rq->q; |
177 | struct list_head *pending = &q->flush_queue[q->flush_pending_idx]; | |
320ae51f | 178 | bool queued = false, kicked; |
ae1b1539 TH |
179 | |
180 | BUG_ON(rq->flush.seq & seq); | |
181 | rq->flush.seq |= seq; | |
182 | ||
183 | if (likely(!error)) | |
184 | seq = blk_flush_cur_seq(rq); | |
185 | else | |
186 | seq = REQ_FSEQ_DONE; | |
187 | ||
188 | switch (seq) { | |
189 | case REQ_FSEQ_PREFLUSH: | |
190 | case REQ_FSEQ_POSTFLUSH: | |
191 | /* queue for flush */ | |
192 | if (list_empty(pending)) | |
193 | q->flush_pending_since = jiffies; | |
194 | list_move_tail(&rq->flush.list, pending); | |
195 | break; | |
196 | ||
197 | case REQ_FSEQ_DATA: | |
198 | list_move_tail(&rq->flush.list, &q->flush_data_in_flight); | |
10beafc1 | 199 | queued = blk_flush_queue_rq(rq, true); |
ae1b1539 TH |
200 | break; |
201 | ||
202 | case REQ_FSEQ_DONE: | |
203 | /* | |
204 | * @rq was previously adjusted by blk_flush_issue() for | |
205 | * flush sequencing and may already have gone through the | |
206 | * flush data request completion path. Restore @rq for | |
207 | * normal completion and end it. | |
208 | */ | |
209 | BUG_ON(!list_empty(&rq->queuelist)); | |
210 | list_del_init(&rq->flush.list); | |
211 | blk_flush_restore_request(rq); | |
320ae51f JA |
212 | if (q->mq_ops) |
213 | blk_mq_end_io(rq, error); | |
214 | else | |
215 | __blk_end_request_all(rq, error); | |
ae1b1539 TH |
216 | break; |
217 | ||
218 | default: | |
219 | BUG(); | |
220 | } | |
221 | ||
320ae51f | 222 | kicked = blk_kick_flush(q); |
320ae51f | 223 | return kicked | queued; |
86db1e29 JA |
224 | } |
225 | ||
ae1b1539 | 226 | static void flush_end_io(struct request *flush_rq, int error) |
86db1e29 | 227 | { |
ae1b1539 | 228 | struct request_queue *q = flush_rq->q; |
320ae51f | 229 | struct list_head *running; |
ae1b1539 TH |
230 | bool queued = false; |
231 | struct request *rq, *n; | |
320ae51f | 232 | unsigned long flags = 0; |
ae1b1539 | 233 | |
18741986 | 234 | if (q->mq_ops) |
320ae51f | 235 | spin_lock_irqsave(&q->mq_flush_lock, flags); |
18741986 | 236 | |
320ae51f | 237 | running = &q->flush_queue[q->flush_running_idx]; |
ae1b1539 TH |
238 | BUG_ON(q->flush_pending_idx == q->flush_running_idx); |
239 | ||
240 | /* account completion of the flush request */ | |
241 | q->flush_running_idx ^= 1; | |
320ae51f JA |
242 | |
243 | if (!q->mq_ops) | |
244 | elv_completed_request(q, flush_rq); | |
ae1b1539 TH |
245 | |
246 | /* and push the waiting requests to the next stage */ | |
247 | list_for_each_entry_safe(rq, n, running, flush.list) { | |
248 | unsigned int seq = blk_flush_cur_seq(rq); | |
249 | ||
250 | BUG_ON(seq != REQ_FSEQ_PREFLUSH && seq != REQ_FSEQ_POSTFLUSH); | |
251 | queued |= blk_flush_complete_seq(rq, seq, error); | |
252 | } | |
253 | ||
47f70d5a | 254 | /* |
3ac0cc45 | 255 | * Kick the queue to avoid stall for two cases: |
256 | * 1. Moving a request silently to empty queue_head may stall the | |
257 | * queue. | |
258 | * 2. When flush request is running in non-queueable queue, the | |
259 | * queue is hold. Restart the queue after flush request is finished | |
260 | * to avoid stall. | |
261 | * This function is called from request completion path and calling | |
262 | * directly into request_fn may confuse the driver. Always use | |
263 | * kblockd. | |
47f70d5a | 264 | */ |
320ae51f | 265 | if (queued || q->flush_queue_delayed) { |
18741986 CH |
266 | WARN_ON(q->mq_ops); |
267 | blk_run_queue_async(q); | |
320ae51f | 268 | } |
3ac0cc45 | 269 | q->flush_queue_delayed = 0; |
320ae51f JA |
270 | if (q->mq_ops) |
271 | spin_unlock_irqrestore(&q->mq_flush_lock, flags); | |
272 | } | |
273 | ||
ae1b1539 TH |
274 | /** |
275 | * blk_kick_flush - consider issuing flush request | |
276 | * @q: request_queue being kicked | |
277 | * | |
278 | * Flush related states of @q have changed, consider issuing flush request. | |
279 | * Please read the comment at the top of this file for more info. | |
280 | * | |
281 | * CONTEXT: | |
320ae51f | 282 | * spin_lock_irq(q->queue_lock or q->mq_flush_lock) |
ae1b1539 TH |
283 | * |
284 | * RETURNS: | |
285 | * %true if flush was issued, %false otherwise. | |
286 | */ | |
287 | static bool blk_kick_flush(struct request_queue *q) | |
86db1e29 | 288 | { |
ae1b1539 TH |
289 | struct list_head *pending = &q->flush_queue[q->flush_pending_idx]; |
290 | struct request *first_rq = | |
291 | list_first_entry(pending, struct request, flush.list); | |
292 | ||
293 | /* C1 described at the top of this file */ | |
294 | if (q->flush_pending_idx != q->flush_running_idx || list_empty(pending)) | |
295 | return false; | |
296 | ||
297 | /* C2 and C3 */ | |
298 | if (!list_empty(&q->flush_data_in_flight) && | |
299 | time_before(jiffies, | |
300 | q->flush_pending_since + FLUSH_PENDING_TIMEOUT)) | |
301 | return false; | |
302 | ||
303 | /* | |
304 | * Issue flush and toggle pending_idx. This makes pending_idx | |
305 | * different from running_idx, which means flush is in flight. | |
306 | */ | |
320ae51f | 307 | q->flush_pending_idx ^= 1; |
18741986 | 308 | |
320ae51f | 309 | if (q->mq_ops) { |
18741986 CH |
310 | struct blk_mq_ctx *ctx = first_rq->mq_ctx; |
311 | struct blk_mq_hw_ctx *hctx = q->mq_ops->map_queue(q, ctx->cpu); | |
312 | ||
313 | blk_mq_rq_init(hctx, q->flush_rq); | |
314 | q->flush_rq->mq_ctx = ctx; | |
315 | ||
316 | /* | |
317 | * Reuse the tag value from the fist waiting request, | |
318 | * with blk-mq the tag is generated during request | |
319 | * allocation and drivers can rely on it being inside | |
320 | * the range they asked for. | |
321 | */ | |
322 | q->flush_rq->tag = first_rq->tag; | |
323 | } else { | |
324 | blk_rq_init(q, q->flush_rq); | |
320ae51f JA |
325 | } |
326 | ||
18741986 CH |
327 | q->flush_rq->cmd_type = REQ_TYPE_FS; |
328 | q->flush_rq->cmd_flags = WRITE_FLUSH | REQ_FLUSH_SEQ; | |
329 | q->flush_rq->rq_disk = first_rq->rq_disk; | |
330 | q->flush_rq->end_io = flush_end_io; | |
ae1b1539 | 331 | |
10beafc1 | 332 | return blk_flush_queue_rq(q->flush_rq, false); |
86db1e29 JA |
333 | } |
334 | ||
ae1b1539 | 335 | static void flush_data_end_io(struct request *rq, int error) |
86db1e29 | 336 | { |
ae1b1539 | 337 | struct request_queue *q = rq->q; |
ae1b1539 | 338 | |
e83a46bb TH |
339 | /* |
340 | * After populating an empty queue, kick it to avoid stall. Read | |
341 | * the comment in flush_end_io(). | |
342 | */ | |
73c10101 | 343 | if (blk_flush_complete_seq(rq, REQ_FSEQ_DATA, error)) |
24ecfbe2 | 344 | blk_run_queue_async(q); |
86db1e29 JA |
345 | } |
346 | ||
320ae51f JA |
347 | static void mq_flush_data_end_io(struct request *rq, int error) |
348 | { | |
349 | struct request_queue *q = rq->q; | |
350 | struct blk_mq_hw_ctx *hctx; | |
351 | struct blk_mq_ctx *ctx; | |
352 | unsigned long flags; | |
353 | ||
354 | ctx = rq->mq_ctx; | |
355 | hctx = q->mq_ops->map_queue(q, ctx->cpu); | |
356 | ||
357 | /* | |
358 | * After populating an empty queue, kick it to avoid stall. Read | |
359 | * the comment in flush_end_io(). | |
360 | */ | |
361 | spin_lock_irqsave(&q->mq_flush_lock, flags); | |
362 | if (blk_flush_complete_seq(rq, REQ_FSEQ_DATA, error)) | |
363 | blk_mq_run_hw_queue(hctx, true); | |
364 | spin_unlock_irqrestore(&q->mq_flush_lock, flags); | |
365 | } | |
366 | ||
ae1b1539 TH |
367 | /** |
368 | * blk_insert_flush - insert a new FLUSH/FUA request | |
369 | * @rq: request to insert | |
370 | * | |
b710a480 | 371 | * To be called from __elv_add_request() for %ELEVATOR_INSERT_FLUSH insertions. |
320ae51f | 372 | * or __blk_mq_run_hw_queue() to dispatch request. |
ae1b1539 TH |
373 | * @rq is being submitted. Analyze what needs to be done and put it on the |
374 | * right queue. | |
375 | * | |
376 | * CONTEXT: | |
320ae51f | 377 | * spin_lock_irq(q->queue_lock) in !mq case |
ae1b1539 TH |
378 | */ |
379 | void blk_insert_flush(struct request *rq) | |
86db1e29 | 380 | { |
ae1b1539 TH |
381 | struct request_queue *q = rq->q; |
382 | unsigned int fflags = q->flush_flags; /* may change, cache */ | |
383 | unsigned int policy = blk_flush_policy(fflags, rq); | |
86db1e29 | 384 | |
ae1b1539 TH |
385 | /* |
386 | * @policy now records what operations need to be done. Adjust | |
387 | * REQ_FLUSH and FUA for the driver. | |
388 | */ | |
18741986 | 389 | rq->cmd_flags &= ~REQ_FLUSH; |
ae1b1539 TH |
390 | if (!(fflags & REQ_FUA)) |
391 | rq->cmd_flags &= ~REQ_FUA; | |
392 | ||
4853abaa JM |
393 | /* |
394 | * An empty flush handed down from a stacking driver may | |
395 | * translate into nothing if the underlying device does not | |
396 | * advertise a write-back cache. In this case, simply | |
397 | * complete the request. | |
398 | */ | |
399 | if (!policy) { | |
320ae51f JA |
400 | if (q->mq_ops) |
401 | blk_mq_end_io(rq, 0); | |
402 | else | |
403 | __blk_end_bidi_request(rq, 0, 0, 0); | |
4853abaa JM |
404 | return; |
405 | } | |
406 | ||
834f9f61 | 407 | BUG_ON(rq->bio != rq->biotail); /*assumes zero or single bio rq */ |
4853abaa | 408 | |
ae1b1539 TH |
409 | /* |
410 | * If there's data but flush is not necessary, the request can be | |
411 | * processed directly without going through flush machinery. Queue | |
412 | * for normal execution. | |
413 | */ | |
414 | if ((policy & REQ_FSEQ_DATA) && | |
415 | !(policy & (REQ_FSEQ_PREFLUSH | REQ_FSEQ_POSTFLUSH))) { | |
320ae51f | 416 | if (q->mq_ops) { |
feb71dae | 417 | blk_mq_insert_request(rq, false, false, true); |
320ae51f JA |
418 | } else |
419 | list_add_tail(&rq->queuelist, &q->queue_head); | |
ae1b1539 | 420 | return; |
28e7d184 | 421 | } |
cde4c406 | 422 | |
ae1b1539 TH |
423 | /* |
424 | * @rq should go through flush machinery. Mark it part of flush | |
425 | * sequence and submit for further processing. | |
426 | */ | |
427 | memset(&rq->flush, 0, sizeof(rq->flush)); | |
428 | INIT_LIST_HEAD(&rq->flush.list); | |
414b4ff5 | 429 | rq->cmd_flags |= REQ_FLUSH_SEQ; |
4853abaa | 430 | rq->flush.saved_end_io = rq->end_io; /* Usually NULL */ |
320ae51f JA |
431 | if (q->mq_ops) { |
432 | rq->end_io = mq_flush_data_end_io; | |
433 | ||
434 | spin_lock_irq(&q->mq_flush_lock); | |
435 | blk_flush_complete_seq(rq, REQ_FSEQ_ACTIONS & ~policy, 0); | |
436 | spin_unlock_irq(&q->mq_flush_lock); | |
437 | return; | |
438 | } | |
ae1b1539 TH |
439 | rq->end_io = flush_data_end_io; |
440 | ||
441 | blk_flush_complete_seq(rq, REQ_FSEQ_ACTIONS & ~policy, 0); | |
86db1e29 JA |
442 | } |
443 | ||
ae1b1539 TH |
444 | /** |
445 | * blk_abort_flushes - @q is being aborted, abort flush requests | |
446 | * @q: request_queue being aborted | |
447 | * | |
448 | * To be called from elv_abort_queue(). @q is being aborted. Prepare all | |
449 | * FLUSH/FUA requests for abortion. | |
450 | * | |
451 | * CONTEXT: | |
452 | * spin_lock_irq(q->queue_lock) | |
453 | */ | |
454 | void blk_abort_flushes(struct request_queue *q) | |
86db1e29 | 455 | { |
ae1b1539 TH |
456 | struct request *rq, *n; |
457 | int i; | |
28e7d184 | 458 | |
4fed947c | 459 | /* |
ae1b1539 TH |
460 | * Requests in flight for data are already owned by the dispatch |
461 | * queue or the device driver. Just restore for normal completion. | |
4fed947c | 462 | */ |
ae1b1539 TH |
463 | list_for_each_entry_safe(rq, n, &q->flush_data_in_flight, flush.list) { |
464 | list_del_init(&rq->flush.list); | |
465 | blk_flush_restore_request(rq); | |
4fed947c | 466 | } |
28e7d184 | 467 | |
4fed947c | 468 | /* |
ae1b1539 TH |
469 | * We need to give away requests on flush queues. Restore for |
470 | * normal completion and put them on the dispatch queue. | |
4fed947c | 471 | */ |
ae1b1539 TH |
472 | for (i = 0; i < ARRAY_SIZE(q->flush_queue); i++) { |
473 | list_for_each_entry_safe(rq, n, &q->flush_queue[i], | |
474 | flush.list) { | |
475 | list_del_init(&rq->flush.list); | |
476 | blk_flush_restore_request(rq); | |
477 | list_add_tail(&rq->queuelist, &q->queue_head); | |
478 | } | |
28e7d184 | 479 | } |
86db1e29 JA |
480 | } |
481 | ||
86db1e29 JA |
482 | /** |
483 | * blkdev_issue_flush - queue a flush | |
484 | * @bdev: blockdev to issue flush for | |
fbd9b09a | 485 | * @gfp_mask: memory allocation flags (for bio_alloc) |
86db1e29 JA |
486 | * @error_sector: error sector |
487 | * | |
488 | * Description: | |
489 | * Issue a flush for the block device in question. Caller can supply | |
490 | * room for storing the error offset in case of a flush error, if they | |
f17e232e DM |
491 | * wish to. If WAIT flag is not passed then caller may check only what |
492 | * request was pushed in some internal queue for later handling. | |
86db1e29 | 493 | */ |
fbd9b09a | 494 | int blkdev_issue_flush(struct block_device *bdev, gfp_t gfp_mask, |
dd3932ed | 495 | sector_t *error_sector) |
86db1e29 | 496 | { |
86db1e29 JA |
497 | struct request_queue *q; |
498 | struct bio *bio; | |
fbd9b09a | 499 | int ret = 0; |
86db1e29 JA |
500 | |
501 | if (bdev->bd_disk == NULL) | |
502 | return -ENXIO; | |
503 | ||
504 | q = bdev_get_queue(bdev); | |
505 | if (!q) | |
506 | return -ENXIO; | |
507 | ||
f10d9f61 DC |
508 | /* |
509 | * some block devices may not have their queue correctly set up here | |
510 | * (e.g. loop device without a backing file) and so issuing a flush | |
511 | * here will panic. Ensure there is a request function before issuing | |
d391a2dd | 512 | * the flush. |
f10d9f61 DC |
513 | */ |
514 | if (!q->make_request_fn) | |
515 | return -ENXIO; | |
516 | ||
fbd9b09a | 517 | bio = bio_alloc(gfp_mask, 0); |
86db1e29 | 518 | bio->bi_bdev = bdev; |
86db1e29 | 519 | |
33879d45 | 520 | ret = submit_bio_wait(WRITE_FLUSH, bio); |
dd3932ed CH |
521 | |
522 | /* | |
523 | * The driver must store the error location in ->bi_sector, if | |
524 | * it supports it. For non-stacked drivers, this should be | |
525 | * copied from blk_rq_pos(rq). | |
526 | */ | |
527 | if (error_sector) | |
4f024f37 | 528 | *error_sector = bio->bi_iter.bi_sector; |
86db1e29 | 529 | |
86db1e29 JA |
530 | bio_put(bio); |
531 | return ret; | |
532 | } | |
86db1e29 | 533 | EXPORT_SYMBOL(blkdev_issue_flush); |
320ae51f JA |
534 | |
535 | void blk_mq_init_flush(struct request_queue *q) | |
536 | { | |
537 | spin_lock_init(&q->mq_flush_lock); | |
320ae51f | 538 | } |