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 | ||
59 | static void pre_flush_end_io(struct request *rq, int error) | |
60 | { | |
61 | elv_completed_request(rq->q, rq); | |
dd4c133f | 62 | blk_flush_complete_seq(rq->q, QUEUE_FSEQ_PREFLUSH, error); |
86db1e29 JA |
63 | } |
64 | ||
dd4c133f | 65 | static void flush_data_end_io(struct request *rq, int error) |
86db1e29 JA |
66 | { |
67 | elv_completed_request(rq->q, rq); | |
dd4c133f | 68 | blk_flush_complete_seq(rq->q, QUEUE_FSEQ_DATA, error); |
86db1e29 JA |
69 | } |
70 | ||
71 | static void post_flush_end_io(struct request *rq, int error) | |
72 | { | |
73 | elv_completed_request(rq->q, rq); | |
dd4c133f | 74 | blk_flush_complete_seq(rq->q, QUEUE_FSEQ_POSTFLUSH, error); |
86db1e29 JA |
75 | } |
76 | ||
28e7d184 TH |
77 | static void queue_flush(struct request_queue *q, struct request *rq, |
78 | rq_end_io_fn *end_io) | |
86db1e29 | 79 | { |
2a4aa30c | 80 | blk_rq_init(q, rq); |
28e18d01 | 81 | rq->cmd_type = REQ_TYPE_FS; |
28e7d184 | 82 | rq->cmd_flags = REQ_FLUSH; |
dd4c133f | 83 | rq->rq_disk = q->orig_flush_rq->rq_disk; |
86db1e29 | 84 | rq->end_io = end_io; |
86db1e29 JA |
85 | |
86 | elv_insert(q, rq, ELEVATOR_INSERT_FRONT); | |
87 | } | |
88 | ||
dd4c133f | 89 | static struct request *queue_next_fseq(struct request_queue *q) |
86db1e29 | 90 | { |
4fed947c | 91 | struct request *orig_rq = q->orig_flush_rq; |
dd4c133f | 92 | struct request *rq = &q->flush_rq; |
86db1e29 | 93 | |
dd4c133f TH |
94 | switch (blk_flush_cur_seq(q)) { |
95 | case QUEUE_FSEQ_PREFLUSH: | |
28e7d184 TH |
96 | queue_flush(q, rq, pre_flush_end_io); |
97 | break; | |
f671620e | 98 | |
dd4c133f | 99 | case QUEUE_FSEQ_DATA: |
4fed947c | 100 | /* initialize proxy request, inherit FLUSH/FUA and queue it */ |
f671620e | 101 | blk_rq_init(q, rq); |
4fed947c TH |
102 | init_request_from_bio(rq, orig_rq->bio); |
103 | rq->cmd_flags &= ~(REQ_FLUSH | REQ_FUA); | |
104 | rq->cmd_flags |= orig_rq->cmd_flags & (REQ_FLUSH | REQ_FUA); | |
dd4c133f | 105 | rq->end_io = flush_data_end_io; |
f671620e TH |
106 | |
107 | elv_insert(q, rq, ELEVATOR_INSERT_FRONT); | |
28e7d184 | 108 | break; |
86db1e29 | 109 | |
dd4c133f | 110 | case QUEUE_FSEQ_POSTFLUSH: |
28e7d184 TH |
111 | queue_flush(q, rq, post_flush_end_io); |
112 | break; | |
86db1e29 | 113 | |
28e7d184 TH |
114 | default: |
115 | BUG(); | |
116 | } | |
dd831006 | 117 | return rq; |
86db1e29 JA |
118 | } |
119 | ||
dd4c133f | 120 | struct request *blk_do_flush(struct request_queue *q, struct request *rq) |
86db1e29 | 121 | { |
4fed947c TH |
122 | unsigned int fflags = q->flush_flags; /* may change, cache it */ |
123 | bool has_flush = fflags & REQ_FLUSH, has_fua = fflags & REQ_FUA; | |
124 | bool do_preflush = has_flush && (rq->cmd_flags & REQ_FLUSH); | |
125 | bool do_postflush = has_flush && !has_fua && (rq->cmd_flags & REQ_FUA); | |
28e7d184 TH |
126 | unsigned skip = 0; |
127 | ||
4fed947c TH |
128 | /* |
129 | * Special case. If there's data but flush is not necessary, | |
130 | * the request can be issued directly. | |
131 | * | |
132 | * Flush w/o data should be able to be issued directly too but | |
133 | * currently some drivers assume that rq->bio contains | |
134 | * non-zero data if it isn't NULL and empty FLUSH requests | |
135 | * getting here usually have bio's without data. | |
136 | */ | |
137 | if (blk_rq_sectors(rq) && !do_preflush && !do_postflush) { | |
138 | rq->cmd_flags &= ~REQ_FLUSH; | |
139 | if (!has_fua) | |
140 | rq->cmd_flags &= ~REQ_FUA; | |
28e7d184 | 141 | return rq; |
4fed947c | 142 | } |
28e7d184 | 143 | |
4fed947c TH |
144 | /* |
145 | * Sequenced flushes can't be processed in parallel. If | |
146 | * another one is already in progress, queue for later | |
147 | * processing. | |
148 | */ | |
dd4c133f | 149 | if (q->flush_seq) { |
dd4c133f | 150 | list_move_tail(&rq->queuelist, &q->pending_flushes); |
28e7d184 TH |
151 | return NULL; |
152 | } | |
153 | ||
86db1e29 | 154 | /* |
dd4c133f | 155 | * Start a new flush sequence |
86db1e29 | 156 | */ |
dd4c133f | 157 | q->flush_err = 0; |
dd4c133f | 158 | q->flush_seq |= QUEUE_FSEQ_STARTED; |
86db1e29 | 159 | |
4fed947c TH |
160 | /* adjust FLUSH/FUA of the original request and stash it away */ |
161 | rq->cmd_flags &= ~REQ_FLUSH; | |
162 | if (!has_fua) | |
163 | rq->cmd_flags &= ~REQ_FUA; | |
28e7d184 | 164 | blk_dequeue_request(rq); |
dd4c133f | 165 | q->orig_flush_rq = rq; |
86db1e29 | 166 | |
4fed947c TH |
167 | /* skip unneded sequences and return the first one */ |
168 | if (!do_preflush) | |
dd4c133f | 169 | skip |= QUEUE_FSEQ_PREFLUSH; |
4fed947c | 170 | if (!blk_rq_sectors(rq)) |
dd4c133f | 171 | skip |= QUEUE_FSEQ_DATA; |
4fed947c | 172 | if (!do_postflush) |
dd4c133f | 173 | skip |= QUEUE_FSEQ_POSTFLUSH; |
dd4c133f | 174 | return blk_flush_complete_seq(q, skip, 0); |
86db1e29 JA |
175 | } |
176 | ||
177 | static void bio_end_empty_barrier(struct bio *bio, int err) | |
178 | { | |
cc66b451 JA |
179 | if (err) { |
180 | if (err == -EOPNOTSUPP) | |
181 | set_bit(BIO_EOPNOTSUPP, &bio->bi_flags); | |
86db1e29 | 182 | clear_bit(BIO_UPTODATE, &bio->bi_flags); |
cc66b451 | 183 | } |
f17e232e DM |
184 | if (bio->bi_private) |
185 | complete(bio->bi_private); | |
186 | bio_put(bio); | |
86db1e29 JA |
187 | } |
188 | ||
189 | /** | |
190 | * blkdev_issue_flush - queue a flush | |
191 | * @bdev: blockdev to issue flush for | |
fbd9b09a | 192 | * @gfp_mask: memory allocation flags (for bio_alloc) |
86db1e29 | 193 | * @error_sector: error sector |
fbd9b09a | 194 | * @flags: BLKDEV_IFL_* flags to control behaviour |
86db1e29 JA |
195 | * |
196 | * Description: | |
197 | * Issue a flush for the block device in question. Caller can supply | |
198 | * room for storing the error offset in case of a flush error, if they | |
f17e232e DM |
199 | * wish to. If WAIT flag is not passed then caller may check only what |
200 | * request was pushed in some internal queue for later handling. | |
86db1e29 | 201 | */ |
fbd9b09a DM |
202 | int blkdev_issue_flush(struct block_device *bdev, gfp_t gfp_mask, |
203 | sector_t *error_sector, unsigned long flags) | |
86db1e29 JA |
204 | { |
205 | DECLARE_COMPLETION_ONSTACK(wait); | |
206 | struct request_queue *q; | |
207 | struct bio *bio; | |
fbd9b09a | 208 | int ret = 0; |
86db1e29 JA |
209 | |
210 | if (bdev->bd_disk == NULL) | |
211 | return -ENXIO; | |
212 | ||
213 | q = bdev_get_queue(bdev); | |
214 | if (!q) | |
215 | return -ENXIO; | |
216 | ||
f10d9f61 DC |
217 | /* |
218 | * some block devices may not have their queue correctly set up here | |
219 | * (e.g. loop device without a backing file) and so issuing a flush | |
220 | * here will panic. Ensure there is a request function before issuing | |
221 | * the barrier. | |
222 | */ | |
223 | if (!q->make_request_fn) | |
224 | return -ENXIO; | |
225 | ||
fbd9b09a | 226 | bio = bio_alloc(gfp_mask, 0); |
86db1e29 | 227 | bio->bi_end_io = bio_end_empty_barrier; |
86db1e29 | 228 | bio->bi_bdev = bdev; |
f17e232e DM |
229 | if (test_bit(BLKDEV_WAIT, &flags)) |
230 | bio->bi_private = &wait; | |
86db1e29 | 231 | |
f17e232e DM |
232 | bio_get(bio); |
233 | submit_bio(WRITE_BARRIER, bio); | |
234 | if (test_bit(BLKDEV_WAIT, &flags)) { | |
235 | wait_for_completion(&wait); | |
236 | /* | |
237 | * The driver must store the error location in ->bi_sector, if | |
238 | * it supports it. For non-stacked drivers, this should be | |
239 | * copied from blk_rq_pos(rq). | |
240 | */ | |
241 | if (error_sector) | |
242 | *error_sector = bio->bi_sector; | |
243 | } | |
86db1e29 | 244 | |
cc66b451 JA |
245 | if (bio_flagged(bio, BIO_EOPNOTSUPP)) |
246 | ret = -EOPNOTSUPP; | |
247 | else if (!bio_flagged(bio, BIO_UPTODATE)) | |
86db1e29 JA |
248 | ret = -EIO; |
249 | ||
250 | bio_put(bio); | |
251 | return ret; | |
252 | } | |
86db1e29 | 253 | EXPORT_SYMBOL(blkdev_issue_flush); |