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4f1043b4 SH |
1 | /* |
2 | * Image streaming | |
3 | * | |
4 | * Copyright IBM, Corp. 2011 | |
5 | * | |
6 | * Authors: | |
7 | * Stefan Hajnoczi <stefanha@linux.vnet.ibm.com> | |
8 | * | |
9 | * This work is licensed under the terms of the GNU LGPL, version 2 or later. | |
10 | * See the COPYING.LIB file in the top-level directory. | |
11 | * | |
12 | */ | |
13 | ||
14 | #include "trace.h" | |
15 | #include "block_int.h" | |
16 | ||
17 | enum { | |
18 | /* | |
19 | * Size of data buffer for populating the image file. This should be large | |
20 | * enough to process multiple clusters in a single call, so that populating | |
21 | * contiguous regions of the image is efficient. | |
22 | */ | |
23 | STREAM_BUFFER_SIZE = 512 * 1024, /* in bytes */ | |
24 | }; | |
25 | ||
5094a6c0 SH |
26 | #define SLICE_TIME 100000000ULL /* ns */ |
27 | ||
28 | typedef struct { | |
29 | int64_t next_slice_time; | |
30 | uint64_t slice_quota; | |
31 | uint64_t dispatched; | |
32 | } RateLimit; | |
33 | ||
34 | static int64_t ratelimit_calculate_delay(RateLimit *limit, uint64_t n) | |
35 | { | |
36 | int64_t delay_ns = 0; | |
37 | int64_t now = qemu_get_clock_ns(rt_clock); | |
38 | ||
39 | if (limit->next_slice_time < now) { | |
40 | limit->next_slice_time = now + SLICE_TIME; | |
41 | limit->dispatched = 0; | |
42 | } | |
43 | if (limit->dispatched + n > limit->slice_quota) { | |
44 | delay_ns = limit->next_slice_time - now; | |
45 | } else { | |
46 | limit->dispatched += n; | |
47 | } | |
48 | return delay_ns; | |
49 | } | |
50 | ||
51 | static void ratelimit_set_speed(RateLimit *limit, uint64_t speed) | |
52 | { | |
53 | limit->slice_quota = speed / (1000000000ULL / SLICE_TIME); | |
54 | } | |
55 | ||
4f1043b4 SH |
56 | typedef struct StreamBlockJob { |
57 | BlockJob common; | |
5094a6c0 | 58 | RateLimit limit; |
4f1043b4 | 59 | BlockDriverState *base; |
c8c3080f | 60 | char backing_file_id[1024]; |
4f1043b4 SH |
61 | } StreamBlockJob; |
62 | ||
63 | static int coroutine_fn stream_populate(BlockDriverState *bs, | |
64 | int64_t sector_num, int nb_sectors, | |
65 | void *buf) | |
66 | { | |
67 | struct iovec iov = { | |
68 | .iov_base = buf, | |
69 | .iov_len = nb_sectors * BDRV_SECTOR_SIZE, | |
70 | }; | |
71 | QEMUIOVector qiov; | |
72 | ||
73 | qemu_iovec_init_external(&qiov, &iov, 1); | |
74 | ||
75 | /* Copy-on-read the unallocated clusters */ | |
76 | return bdrv_co_copy_on_readv(bs, sector_num, nb_sectors, &qiov); | |
77 | } | |
78 | ||
c8c3080f MT |
79 | /* |
80 | * Given an image chain: [BASE] -> [INTER1] -> [INTER2] -> [TOP] | |
81 | * | |
82 | * Return true if the given sector is allocated in top. | |
83 | * Return false if the given sector is allocated in intermediate images. | |
84 | * Return true otherwise. | |
85 | * | |
86 | * 'pnum' is set to the number of sectors (including and immediately following | |
87 | * the specified sector) that are known to be in the same | |
88 | * allocated/unallocated state. | |
89 | * | |
90 | */ | |
91 | static int coroutine_fn is_allocated_base(BlockDriverState *top, | |
92 | BlockDriverState *base, | |
93 | int64_t sector_num, | |
94 | int nb_sectors, int *pnum) | |
95 | { | |
96 | BlockDriverState *intermediate; | |
97 | int ret, n; | |
98 | ||
99 | ret = bdrv_co_is_allocated(top, sector_num, nb_sectors, &n); | |
100 | if (ret) { | |
101 | *pnum = n; | |
102 | return ret; | |
103 | } | |
104 | ||
105 | /* | |
106 | * Is the unallocated chunk [sector_num, n] also | |
107 | * unallocated between base and top? | |
108 | */ | |
109 | intermediate = top->backing_hd; | |
110 | ||
111 | while (intermediate) { | |
112 | int pnum_inter; | |
113 | ||
114 | /* reached base */ | |
115 | if (intermediate == base) { | |
116 | *pnum = n; | |
117 | return 1; | |
118 | } | |
119 | ret = bdrv_co_is_allocated(intermediate, sector_num, nb_sectors, | |
120 | &pnum_inter); | |
121 | if (ret < 0) { | |
122 | return ret; | |
123 | } else if (ret) { | |
124 | *pnum = pnum_inter; | |
125 | return 0; | |
126 | } | |
127 | ||
128 | /* | |
129 | * [sector_num, nb_sectors] is unallocated on top but intermediate | |
130 | * might have | |
131 | * | |
132 | * [sector_num+x, nr_sectors] allocated. | |
133 | */ | |
134 | if (n > pnum_inter) { | |
135 | n = pnum_inter; | |
136 | } | |
137 | ||
138 | intermediate = intermediate->backing_hd; | |
139 | } | |
140 | ||
141 | return 1; | |
142 | } | |
143 | ||
4f1043b4 SH |
144 | static void coroutine_fn stream_run(void *opaque) |
145 | { | |
146 | StreamBlockJob *s = opaque; | |
147 | BlockDriverState *bs = s->common.bs; | |
c8c3080f | 148 | BlockDriverState *base = s->base; |
4f1043b4 SH |
149 | int64_t sector_num, end; |
150 | int ret = 0; | |
151 | int n; | |
152 | void *buf; | |
153 | ||
154 | s->common.len = bdrv_getlength(bs); | |
155 | if (s->common.len < 0) { | |
156 | block_job_complete(&s->common, s->common.len); | |
157 | return; | |
158 | } | |
159 | ||
160 | end = s->common.len >> BDRV_SECTOR_BITS; | |
161 | buf = qemu_blockalign(bs, STREAM_BUFFER_SIZE); | |
162 | ||
163 | /* Turn on copy-on-read for the whole block device so that guest read | |
164 | * requests help us make progress. Only do this when copying the entire | |
165 | * backing chain since the copy-on-read operation does not take base into | |
166 | * account. | |
167 | */ | |
168 | if (!base) { | |
169 | bdrv_enable_copy_on_read(bs); | |
170 | } | |
171 | ||
172 | for (sector_num = 0; sector_num < end; sector_num += n) { | |
5094a6c0 | 173 | retry: |
4f1043b4 SH |
174 | if (block_job_is_cancelled(&s->common)) { |
175 | break; | |
176 | } | |
177 | ||
c8c3080f MT |
178 | |
179 | if (base) { | |
180 | ret = is_allocated_base(bs, base, sector_num, | |
181 | STREAM_BUFFER_SIZE / BDRV_SECTOR_SIZE, &n); | |
182 | } else { | |
183 | ret = bdrv_co_is_allocated(bs, sector_num, | |
184 | STREAM_BUFFER_SIZE / BDRV_SECTOR_SIZE, | |
185 | &n); | |
186 | } | |
4f1043b4 SH |
187 | trace_stream_one_iteration(s, sector_num, n, ret); |
188 | if (ret == 0) { | |
5094a6c0 SH |
189 | if (s->common.speed) { |
190 | uint64_t delay_ns = ratelimit_calculate_delay(&s->limit, n); | |
191 | if (delay_ns > 0) { | |
192 | co_sleep_ns(rt_clock, delay_ns); | |
193 | ||
194 | /* Recheck cancellation and that sectors are unallocated */ | |
195 | goto retry; | |
196 | } | |
197 | } | |
4f1043b4 SH |
198 | ret = stream_populate(bs, sector_num, n, buf); |
199 | } | |
200 | if (ret < 0) { | |
201 | break; | |
202 | } | |
c8c3080f | 203 | ret = 0; |
4f1043b4 SH |
204 | |
205 | /* Publish progress */ | |
206 | s->common.offset += n * BDRV_SECTOR_SIZE; | |
5094a6c0 SH |
207 | |
208 | /* Note that even when no rate limit is applied we need to yield | |
209 | * with no pending I/O here so that qemu_aio_flush() returns. | |
210 | */ | |
211 | co_sleep_ns(rt_clock, 0); | |
4f1043b4 SH |
212 | } |
213 | ||
214 | if (!base) { | |
215 | bdrv_disable_copy_on_read(bs); | |
216 | } | |
217 | ||
218 | if (sector_num == end && ret == 0) { | |
c8c3080f MT |
219 | const char *base_id = NULL; |
220 | if (base) { | |
221 | base_id = s->backing_file_id; | |
222 | } | |
223 | ret = bdrv_change_backing_file(bs, base_id, NULL); | |
4f1043b4 SH |
224 | } |
225 | ||
226 | qemu_vfree(buf); | |
227 | block_job_complete(&s->common, ret); | |
228 | } | |
229 | ||
5094a6c0 SH |
230 | static int stream_set_speed(BlockJob *job, int64_t value) |
231 | { | |
232 | StreamBlockJob *s = container_of(job, StreamBlockJob, common); | |
233 | ||
234 | if (value < 0) { | |
235 | return -EINVAL; | |
236 | } | |
237 | job->speed = value; | |
238 | ratelimit_set_speed(&s->limit, value / BDRV_SECTOR_SIZE); | |
239 | return 0; | |
240 | } | |
241 | ||
4f1043b4 SH |
242 | static BlockJobType stream_job_type = { |
243 | .instance_size = sizeof(StreamBlockJob), | |
244 | .job_type = "stream", | |
5094a6c0 | 245 | .set_speed = stream_set_speed, |
4f1043b4 SH |
246 | }; |
247 | ||
248 | int stream_start(BlockDriverState *bs, BlockDriverState *base, | |
c8c3080f MT |
249 | const char *base_id, BlockDriverCompletionFunc *cb, |
250 | void *opaque) | |
4f1043b4 SH |
251 | { |
252 | StreamBlockJob *s; | |
253 | Coroutine *co; | |
254 | ||
255 | s = block_job_create(&stream_job_type, bs, cb, opaque); | |
256 | if (!s) { | |
257 | return -EBUSY; /* bs must already be in use */ | |
258 | } | |
259 | ||
260 | s->base = base; | |
c8c3080f MT |
261 | if (base_id) { |
262 | pstrcpy(s->backing_file_id, sizeof(s->backing_file_id), base_id); | |
263 | } | |
4f1043b4 SH |
264 | |
265 | co = qemu_coroutine_create(stream_run); | |
266 | trace_stream_start(bs, base, s, co, opaque); | |
267 | qemu_coroutine_enter(co, s); | |
268 | return 0; | |
269 | } |