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 | ||
cde4c406 | 77 | static void init_flush_request(struct request *rq, struct gendisk *disk) |
86db1e29 | 78 | { |
28e18d01 | 79 | rq->cmd_type = REQ_TYPE_FS; |
337238be | 80 | rq->cmd_flags = WRITE_FLUSH; |
cde4c406 | 81 | rq->rq_disk = disk; |
86db1e29 JA |
82 | } |
83 | ||
dd4c133f | 84 | static struct request *queue_next_fseq(struct request_queue *q) |
86db1e29 | 85 | { |
4fed947c | 86 | struct request *orig_rq = q->orig_flush_rq; |
dd4c133f | 87 | struct request *rq = &q->flush_rq; |
86db1e29 | 88 | |
cde4c406 CH |
89 | blk_rq_init(q, rq); |
90 | ||
dd4c133f TH |
91 | switch (blk_flush_cur_seq(q)) { |
92 | case QUEUE_FSEQ_PREFLUSH: | |
cde4c406 CH |
93 | init_flush_request(rq, orig_rq->rq_disk); |
94 | rq->end_io = pre_flush_end_io; | |
28e7d184 | 95 | break; |
dd4c133f | 96 | case QUEUE_FSEQ_DATA: |
4fed947c TH |
97 | init_request_from_bio(rq, orig_rq->bio); |
98 | rq->cmd_flags &= ~(REQ_FLUSH | REQ_FUA); | |
99 | rq->cmd_flags |= orig_rq->cmd_flags & (REQ_FLUSH | REQ_FUA); | |
dd4c133f | 100 | rq->end_io = flush_data_end_io; |
28e7d184 | 101 | break; |
dd4c133f | 102 | case QUEUE_FSEQ_POSTFLUSH: |
cde4c406 CH |
103 | init_flush_request(rq, orig_rq->rq_disk); |
104 | rq->end_io = post_flush_end_io; | |
28e7d184 | 105 | break; |
28e7d184 TH |
106 | default: |
107 | BUG(); | |
108 | } | |
cde4c406 CH |
109 | |
110 | elv_insert(q, rq, ELEVATOR_INSERT_FRONT); | |
dd831006 | 111 | return rq; |
86db1e29 JA |
112 | } |
113 | ||
dd4c133f | 114 | struct request *blk_do_flush(struct request_queue *q, struct request *rq) |
86db1e29 | 115 | { |
4fed947c TH |
116 | unsigned int fflags = q->flush_flags; /* may change, cache it */ |
117 | bool has_flush = fflags & REQ_FLUSH, has_fua = fflags & REQ_FUA; | |
118 | bool do_preflush = has_flush && (rq->cmd_flags & REQ_FLUSH); | |
119 | bool do_postflush = has_flush && !has_fua && (rq->cmd_flags & REQ_FUA); | |
28e7d184 TH |
120 | unsigned skip = 0; |
121 | ||
4fed947c TH |
122 | /* |
123 | * Special case. If there's data but flush is not necessary, | |
124 | * the request can be issued directly. | |
125 | * | |
126 | * Flush w/o data should be able to be issued directly too but | |
127 | * currently some drivers assume that rq->bio contains | |
128 | * non-zero data if it isn't NULL and empty FLUSH requests | |
129 | * getting here usually have bio's without data. | |
130 | */ | |
131 | if (blk_rq_sectors(rq) && !do_preflush && !do_postflush) { | |
132 | rq->cmd_flags &= ~REQ_FLUSH; | |
133 | if (!has_fua) | |
134 | rq->cmd_flags &= ~REQ_FUA; | |
28e7d184 | 135 | return rq; |
4fed947c | 136 | } |
28e7d184 | 137 | |
4fed947c TH |
138 | /* |
139 | * Sequenced flushes can't be processed in parallel. If | |
140 | * another one is already in progress, queue for later | |
141 | * processing. | |
142 | */ | |
dd4c133f | 143 | if (q->flush_seq) { |
dd4c133f | 144 | list_move_tail(&rq->queuelist, &q->pending_flushes); |
28e7d184 TH |
145 | return NULL; |
146 | } | |
147 | ||
86db1e29 | 148 | /* |
dd4c133f | 149 | * Start a new flush sequence |
86db1e29 | 150 | */ |
dd4c133f | 151 | q->flush_err = 0; |
dd4c133f | 152 | q->flush_seq |= QUEUE_FSEQ_STARTED; |
86db1e29 | 153 | |
4fed947c TH |
154 | /* adjust FLUSH/FUA of the original request and stash it away */ |
155 | rq->cmd_flags &= ~REQ_FLUSH; | |
156 | if (!has_fua) | |
157 | rq->cmd_flags &= ~REQ_FUA; | |
28e7d184 | 158 | blk_dequeue_request(rq); |
dd4c133f | 159 | q->orig_flush_rq = rq; |
86db1e29 | 160 | |
4fed947c TH |
161 | /* skip unneded sequences and return the first one */ |
162 | if (!do_preflush) | |
dd4c133f | 163 | skip |= QUEUE_FSEQ_PREFLUSH; |
4fed947c | 164 | if (!blk_rq_sectors(rq)) |
dd4c133f | 165 | skip |= QUEUE_FSEQ_DATA; |
4fed947c | 166 | if (!do_postflush) |
dd4c133f | 167 | skip |= QUEUE_FSEQ_POSTFLUSH; |
dd4c133f | 168 | return blk_flush_complete_seq(q, skip, 0); |
86db1e29 JA |
169 | } |
170 | ||
171 | static void bio_end_empty_barrier(struct bio *bio, int err) | |
172 | { | |
cc66b451 JA |
173 | if (err) { |
174 | if (err == -EOPNOTSUPP) | |
175 | set_bit(BIO_EOPNOTSUPP, &bio->bi_flags); | |
86db1e29 | 176 | clear_bit(BIO_UPTODATE, &bio->bi_flags); |
cc66b451 | 177 | } |
f17e232e DM |
178 | if (bio->bi_private) |
179 | complete(bio->bi_private); | |
180 | bio_put(bio); | |
86db1e29 JA |
181 | } |
182 | ||
183 | /** | |
184 | * blkdev_issue_flush - queue a flush | |
185 | * @bdev: blockdev to issue flush for | |
fbd9b09a | 186 | * @gfp_mask: memory allocation flags (for bio_alloc) |
86db1e29 | 187 | * @error_sector: error sector |
fbd9b09a | 188 | * @flags: BLKDEV_IFL_* flags to control behaviour |
86db1e29 JA |
189 | * |
190 | * Description: | |
191 | * Issue a flush for the block device in question. Caller can supply | |
192 | * room for storing the error offset in case of a flush error, if they | |
f17e232e DM |
193 | * wish to. If WAIT flag is not passed then caller may check only what |
194 | * request was pushed in some internal queue for later handling. | |
86db1e29 | 195 | */ |
fbd9b09a DM |
196 | int blkdev_issue_flush(struct block_device *bdev, gfp_t gfp_mask, |
197 | sector_t *error_sector, unsigned long flags) | |
86db1e29 JA |
198 | { |
199 | DECLARE_COMPLETION_ONSTACK(wait); | |
200 | struct request_queue *q; | |
201 | struct bio *bio; | |
fbd9b09a | 202 | int ret = 0; |
86db1e29 JA |
203 | |
204 | if (bdev->bd_disk == NULL) | |
205 | return -ENXIO; | |
206 | ||
207 | q = bdev_get_queue(bdev); | |
208 | if (!q) | |
209 | return -ENXIO; | |
210 | ||
f10d9f61 DC |
211 | /* |
212 | * some block devices may not have their queue correctly set up here | |
213 | * (e.g. loop device without a backing file) and so issuing a flush | |
214 | * here will panic. Ensure there is a request function before issuing | |
215 | * the barrier. | |
216 | */ | |
217 | if (!q->make_request_fn) | |
218 | return -ENXIO; | |
219 | ||
fbd9b09a | 220 | bio = bio_alloc(gfp_mask, 0); |
86db1e29 | 221 | bio->bi_end_io = bio_end_empty_barrier; |
86db1e29 | 222 | bio->bi_bdev = bdev; |
f17e232e DM |
223 | if (test_bit(BLKDEV_WAIT, &flags)) |
224 | bio->bi_private = &wait; | |
86db1e29 | 225 | |
f17e232e DM |
226 | bio_get(bio); |
227 | submit_bio(WRITE_BARRIER, bio); | |
228 | if (test_bit(BLKDEV_WAIT, &flags)) { | |
229 | wait_for_completion(&wait); | |
230 | /* | |
231 | * The driver must store the error location in ->bi_sector, if | |
232 | * it supports it. For non-stacked drivers, this should be | |
233 | * copied from blk_rq_pos(rq). | |
234 | */ | |
235 | if (error_sector) | |
236 | *error_sector = bio->bi_sector; | |
237 | } | |
86db1e29 | 238 | |
cc66b451 JA |
239 | if (bio_flagged(bio, BIO_EOPNOTSUPP)) |
240 | ret = -EOPNOTSUPP; | |
241 | else if (!bio_flagged(bio, BIO_UPTODATE)) | |
86db1e29 JA |
242 | ret = -EIO; |
243 | ||
244 | bio_put(bio); | |
245 | return ret; | |
246 | } | |
86db1e29 | 247 | EXPORT_SYMBOL(blkdev_issue_flush); |