Commit | Line | Data |
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86db1e29 | 1 | /* |
4fed947c | 2 | * Functions to sequence FLUSH and FUA writes. |
86db1e29 JA |
3 | */ |
4 | #include <linux/kernel.h> | |
5 | #include <linux/module.h> | |
6 | #include <linux/bio.h> | |
7 | #include <linux/blkdev.h> | |
5a0e3ad6 | 8 | #include <linux/gfp.h> |
86db1e29 JA |
9 | |
10 | #include "blk.h" | |
11 | ||
4fed947c TH |
12 | /* FLUSH/FUA sequences */ |
13 | enum { | |
14 | QUEUE_FSEQ_STARTED = (1 << 0), /* flushing in progress */ | |
15 | QUEUE_FSEQ_PREFLUSH = (1 << 1), /* pre-flushing in progress */ | |
16 | QUEUE_FSEQ_DATA = (1 << 2), /* data write in progress */ | |
17 | QUEUE_FSEQ_POSTFLUSH = (1 << 3), /* post-flushing in progress */ | |
18 | QUEUE_FSEQ_DONE = (1 << 4), | |
19 | }; | |
20 | ||
dd4c133f | 21 | static struct request *queue_next_fseq(struct request_queue *q); |
28e7d184 | 22 | |
dd4c133f | 23 | unsigned blk_flush_cur_seq(struct request_queue *q) |
86db1e29 | 24 | { |
dd4c133f | 25 | if (!q->flush_seq) |
86db1e29 | 26 | return 0; |
dd4c133f | 27 | return 1 << ffz(q->flush_seq); |
86db1e29 JA |
28 | } |
29 | ||
dd4c133f TH |
30 | static struct request *blk_flush_complete_seq(struct request_queue *q, |
31 | unsigned seq, int error) | |
86db1e29 | 32 | { |
28e7d184 | 33 | struct request *next_rq = NULL; |
86db1e29 | 34 | |
dd4c133f TH |
35 | if (error && !q->flush_err) |
36 | q->flush_err = error; | |
86db1e29 | 37 | |
dd4c133f TH |
38 | BUG_ON(q->flush_seq & seq); |
39 | q->flush_seq |= seq; | |
86db1e29 | 40 | |
dd4c133f TH |
41 | if (blk_flush_cur_seq(q) != QUEUE_FSEQ_DONE) { |
42 | /* not complete yet, queue the next flush sequence */ | |
43 | next_rq = queue_next_fseq(q); | |
28e7d184 | 44 | } else { |
dd4c133f TH |
45 | /* complete this flush request */ |
46 | __blk_end_request_all(q->orig_flush_rq, q->flush_err); | |
47 | q->orig_flush_rq = NULL; | |
48 | q->flush_seq = 0; | |
49 | ||
50 | /* dispatch the next flush if there's one */ | |
51 | if (!list_empty(&q->pending_flushes)) { | |
52 | next_rq = list_entry_rq(q->pending_flushes.next); | |
28e7d184 TH |
53 | list_move(&next_rq->queuelist, &q->queue_head); |
54 | } | |
55 | } | |
56 | return next_rq; | |
86db1e29 JA |
57 | } |
58 | ||
47f70d5a TH |
59 | static void blk_flush_complete_seq_end_io(struct request_queue *q, |
60 | unsigned seq, int error) | |
61 | { | |
62 | bool was_empty = elv_queue_empty(q); | |
63 | struct request *next_rq; | |
64 | ||
65 | next_rq = blk_flush_complete_seq(q, seq, error); | |
66 | ||
67 | /* | |
68 | * Moving a request silently to empty queue_head may stall the | |
255bb490 TH |
69 | * queue. Kick the queue in those cases. This function is called |
70 | * from request completion path and calling directly into | |
71 | * request_fn may confuse the driver. Always use kblockd. | |
47f70d5a TH |
72 | */ |
73 | if (was_empty && next_rq) | |
255bb490 | 74 | __blk_run_queue(q, true); |
47f70d5a TH |
75 | } |
76 | ||
86db1e29 JA |
77 | static void pre_flush_end_io(struct request *rq, int error) |
78 | { | |
79 | elv_completed_request(rq->q, rq); | |
47f70d5a | 80 | blk_flush_complete_seq_end_io(rq->q, QUEUE_FSEQ_PREFLUSH, error); |
86db1e29 JA |
81 | } |
82 | ||
dd4c133f | 83 | static void flush_data_end_io(struct request *rq, int error) |
86db1e29 JA |
84 | { |
85 | elv_completed_request(rq->q, rq); | |
47f70d5a | 86 | blk_flush_complete_seq_end_io(rq->q, QUEUE_FSEQ_DATA, error); |
86db1e29 JA |
87 | } |
88 | ||
89 | static void post_flush_end_io(struct request *rq, int error) | |
90 | { | |
91 | elv_completed_request(rq->q, rq); | |
47f70d5a | 92 | blk_flush_complete_seq_end_io(rq->q, QUEUE_FSEQ_POSTFLUSH, error); |
86db1e29 JA |
93 | } |
94 | ||
cde4c406 | 95 | static void init_flush_request(struct request *rq, struct gendisk *disk) |
86db1e29 | 96 | { |
28e18d01 | 97 | rq->cmd_type = REQ_TYPE_FS; |
337238be | 98 | rq->cmd_flags = WRITE_FLUSH; |
cde4c406 | 99 | rq->rq_disk = disk; |
86db1e29 JA |
100 | } |
101 | ||
dd4c133f | 102 | static struct request *queue_next_fseq(struct request_queue *q) |
86db1e29 | 103 | { |
4fed947c | 104 | struct request *orig_rq = q->orig_flush_rq; |
dd4c133f | 105 | struct request *rq = &q->flush_rq; |
86db1e29 | 106 | |
cde4c406 CH |
107 | blk_rq_init(q, rq); |
108 | ||
dd4c133f TH |
109 | switch (blk_flush_cur_seq(q)) { |
110 | case QUEUE_FSEQ_PREFLUSH: | |
cde4c406 CH |
111 | init_flush_request(rq, orig_rq->rq_disk); |
112 | rq->end_io = pre_flush_end_io; | |
28e7d184 | 113 | break; |
dd4c133f | 114 | case QUEUE_FSEQ_DATA: |
4fed947c | 115 | init_request_from_bio(rq, orig_rq->bio); |
09d60c70 TH |
116 | /* |
117 | * orig_rq->rq_disk may be different from | |
118 | * bio->bi_bdev->bd_disk if orig_rq got here through | |
119 | * remapping drivers. Make sure rq->rq_disk points | |
120 | * to the same one as orig_rq. | |
121 | */ | |
122 | rq->rq_disk = orig_rq->rq_disk; | |
4fed947c TH |
123 | rq->cmd_flags &= ~(REQ_FLUSH | REQ_FUA); |
124 | rq->cmd_flags |= orig_rq->cmd_flags & (REQ_FLUSH | REQ_FUA); | |
dd4c133f | 125 | rq->end_io = flush_data_end_io; |
28e7d184 | 126 | break; |
dd4c133f | 127 | case QUEUE_FSEQ_POSTFLUSH: |
cde4c406 CH |
128 | init_flush_request(rq, orig_rq->rq_disk); |
129 | rq->end_io = post_flush_end_io; | |
28e7d184 | 130 | break; |
28e7d184 TH |
131 | default: |
132 | BUG(); | |
133 | } | |
cde4c406 | 134 | |
255bb490 | 135 | elv_insert(q, rq, ELEVATOR_INSERT_REQUEUE); |
dd831006 | 136 | return rq; |
86db1e29 JA |
137 | } |
138 | ||
dd4c133f | 139 | struct request *blk_do_flush(struct request_queue *q, struct request *rq) |
86db1e29 | 140 | { |
4fed947c TH |
141 | unsigned int fflags = q->flush_flags; /* may change, cache it */ |
142 | bool has_flush = fflags & REQ_FLUSH, has_fua = fflags & REQ_FUA; | |
143 | bool do_preflush = has_flush && (rq->cmd_flags & REQ_FLUSH); | |
144 | bool do_postflush = has_flush && !has_fua && (rq->cmd_flags & REQ_FUA); | |
28e7d184 TH |
145 | unsigned skip = 0; |
146 | ||
4fed947c TH |
147 | /* |
148 | * Special case. If there's data but flush is not necessary, | |
149 | * the request can be issued directly. | |
150 | * | |
151 | * Flush w/o data should be able to be issued directly too but | |
152 | * currently some drivers assume that rq->bio contains | |
153 | * non-zero data if it isn't NULL and empty FLUSH requests | |
154 | * getting here usually have bio's without data. | |
155 | */ | |
156 | if (blk_rq_sectors(rq) && !do_preflush && !do_postflush) { | |
157 | rq->cmd_flags &= ~REQ_FLUSH; | |
158 | if (!has_fua) | |
159 | rq->cmd_flags &= ~REQ_FUA; | |
28e7d184 | 160 | return rq; |
4fed947c | 161 | } |
28e7d184 | 162 | |
4fed947c TH |
163 | /* |
164 | * Sequenced flushes can't be processed in parallel. If | |
165 | * another one is already in progress, queue for later | |
166 | * processing. | |
167 | */ | |
dd4c133f | 168 | if (q->flush_seq) { |
dd4c133f | 169 | list_move_tail(&rq->queuelist, &q->pending_flushes); |
28e7d184 TH |
170 | return NULL; |
171 | } | |
172 | ||
86db1e29 | 173 | /* |
dd4c133f | 174 | * Start a new flush sequence |
86db1e29 | 175 | */ |
dd4c133f | 176 | q->flush_err = 0; |
dd4c133f | 177 | q->flush_seq |= QUEUE_FSEQ_STARTED; |
86db1e29 | 178 | |
4fed947c TH |
179 | /* adjust FLUSH/FUA of the original request and stash it away */ |
180 | rq->cmd_flags &= ~REQ_FLUSH; | |
181 | if (!has_fua) | |
182 | rq->cmd_flags &= ~REQ_FUA; | |
28e7d184 | 183 | blk_dequeue_request(rq); |
dd4c133f | 184 | q->orig_flush_rq = rq; |
86db1e29 | 185 | |
4fed947c TH |
186 | /* skip unneded sequences and return the first one */ |
187 | if (!do_preflush) | |
dd4c133f | 188 | skip |= QUEUE_FSEQ_PREFLUSH; |
4fed947c | 189 | if (!blk_rq_sectors(rq)) |
dd4c133f | 190 | skip |= QUEUE_FSEQ_DATA; |
4fed947c | 191 | if (!do_postflush) |
dd4c133f | 192 | skip |= QUEUE_FSEQ_POSTFLUSH; |
dd4c133f | 193 | return blk_flush_complete_seq(q, skip, 0); |
86db1e29 JA |
194 | } |
195 | ||
d391a2dd | 196 | static void bio_end_flush(struct bio *bio, int err) |
86db1e29 | 197 | { |
d391a2dd | 198 | if (err) |
86db1e29 | 199 | clear_bit(BIO_UPTODATE, &bio->bi_flags); |
f17e232e DM |
200 | if (bio->bi_private) |
201 | complete(bio->bi_private); | |
202 | bio_put(bio); | |
86db1e29 JA |
203 | } |
204 | ||
205 | /** | |
206 | * blkdev_issue_flush - queue a flush | |
207 | * @bdev: blockdev to issue flush for | |
fbd9b09a | 208 | * @gfp_mask: memory allocation flags (for bio_alloc) |
86db1e29 JA |
209 | * @error_sector: error sector |
210 | * | |
211 | * Description: | |
212 | * Issue a flush for the block device in question. Caller can supply | |
213 | * room for storing the error offset in case of a flush error, if they | |
f17e232e DM |
214 | * wish to. If WAIT flag is not passed then caller may check only what |
215 | * request was pushed in some internal queue for later handling. | |
86db1e29 | 216 | */ |
fbd9b09a | 217 | int blkdev_issue_flush(struct block_device *bdev, gfp_t gfp_mask, |
dd3932ed | 218 | sector_t *error_sector) |
86db1e29 JA |
219 | { |
220 | DECLARE_COMPLETION_ONSTACK(wait); | |
221 | struct request_queue *q; | |
222 | struct bio *bio; | |
fbd9b09a | 223 | int ret = 0; |
86db1e29 JA |
224 | |
225 | if (bdev->bd_disk == NULL) | |
226 | return -ENXIO; | |
227 | ||
228 | q = bdev_get_queue(bdev); | |
229 | if (!q) | |
230 | return -ENXIO; | |
231 | ||
f10d9f61 DC |
232 | /* |
233 | * some block devices may not have their queue correctly set up here | |
234 | * (e.g. loop device without a backing file) and so issuing a flush | |
235 | * here will panic. Ensure there is a request function before issuing | |
d391a2dd | 236 | * the flush. |
f10d9f61 DC |
237 | */ |
238 | if (!q->make_request_fn) | |
239 | return -ENXIO; | |
240 | ||
fbd9b09a | 241 | bio = bio_alloc(gfp_mask, 0); |
d391a2dd | 242 | bio->bi_end_io = bio_end_flush; |
86db1e29 | 243 | bio->bi_bdev = bdev; |
dd3932ed | 244 | bio->bi_private = &wait; |
86db1e29 | 245 | |
f17e232e | 246 | bio_get(bio); |
d391a2dd | 247 | submit_bio(WRITE_FLUSH, bio); |
dd3932ed CH |
248 | wait_for_completion(&wait); |
249 | ||
250 | /* | |
251 | * The driver must store the error location in ->bi_sector, if | |
252 | * it supports it. For non-stacked drivers, this should be | |
253 | * copied from blk_rq_pos(rq). | |
254 | */ | |
255 | if (error_sector) | |
256 | *error_sector = bio->bi_sector; | |
86db1e29 | 257 | |
d391a2dd | 258 | if (!bio_flagged(bio, BIO_UPTODATE)) |
86db1e29 JA |
259 | ret = -EIO; |
260 | ||
261 | bio_put(bio); | |
262 | return ret; | |
263 | } | |
86db1e29 | 264 | EXPORT_SYMBOL(blkdev_issue_flush); |