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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 | { | |
5094a6c0 SH |
36 | int64_t now = qemu_get_clock_ns(rt_clock); |
37 | ||
38 | if (limit->next_slice_time < now) { | |
39 | limit->next_slice_time = now + SLICE_TIME; | |
40 | limit->dispatched = 0; | |
41 | } | |
b21d677e | 42 | if (limit->dispatched == 0 || limit->dispatched + n <= limit->slice_quota) { |
5094a6c0 | 43 | limit->dispatched += n; |
b21d677e PB |
44 | return 0; |
45 | } else { | |
46 | limit->dispatched = n; | |
47 | return limit->next_slice_time - now; | |
5094a6c0 | 48 | } |
5094a6c0 SH |
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 | ||
5a67a104 MT |
79 | static void close_unused_images(BlockDriverState *top, BlockDriverState *base, |
80 | const char *base_id) | |
81 | { | |
82 | BlockDriverState *intermediate; | |
83 | intermediate = top->backing_hd; | |
84 | ||
85 | while (intermediate) { | |
86 | BlockDriverState *unused; | |
87 | ||
88 | /* reached base */ | |
89 | if (intermediate == base) { | |
90 | break; | |
91 | } | |
92 | ||
93 | unused = intermediate; | |
94 | intermediate = intermediate->backing_hd; | |
95 | unused->backing_hd = NULL; | |
96 | bdrv_delete(unused); | |
97 | } | |
98 | top->backing_hd = base; | |
5a67a104 MT |
99 | } |
100 | ||
c8c3080f MT |
101 | /* |
102 | * Given an image chain: [BASE] -> [INTER1] -> [INTER2] -> [TOP] | |
103 | * | |
104 | * Return true if the given sector is allocated in top. | |
105 | * Return false if the given sector is allocated in intermediate images. | |
106 | * Return true otherwise. | |
107 | * | |
108 | * 'pnum' is set to the number of sectors (including and immediately following | |
109 | * the specified sector) that are known to be in the same | |
110 | * allocated/unallocated state. | |
111 | * | |
112 | */ | |
113 | static int coroutine_fn is_allocated_base(BlockDriverState *top, | |
114 | BlockDriverState *base, | |
115 | int64_t sector_num, | |
116 | int nb_sectors, int *pnum) | |
117 | { | |
118 | BlockDriverState *intermediate; | |
119 | int ret, n; | |
120 | ||
121 | ret = bdrv_co_is_allocated(top, sector_num, nb_sectors, &n); | |
122 | if (ret) { | |
123 | *pnum = n; | |
124 | return ret; | |
125 | } | |
126 | ||
127 | /* | |
128 | * Is the unallocated chunk [sector_num, n] also | |
129 | * unallocated between base and top? | |
130 | */ | |
131 | intermediate = top->backing_hd; | |
132 | ||
efcc7a23 | 133 | while (intermediate != base) { |
c8c3080f MT |
134 | int pnum_inter; |
135 | ||
c8c3080f MT |
136 | ret = bdrv_co_is_allocated(intermediate, sector_num, nb_sectors, |
137 | &pnum_inter); | |
138 | if (ret < 0) { | |
139 | return ret; | |
140 | } else if (ret) { | |
141 | *pnum = pnum_inter; | |
142 | return 0; | |
143 | } | |
144 | ||
145 | /* | |
146 | * [sector_num, nb_sectors] is unallocated on top but intermediate | |
147 | * might have | |
148 | * | |
149 | * [sector_num+x, nr_sectors] allocated. | |
150 | */ | |
151 | if (n > pnum_inter) { | |
152 | n = pnum_inter; | |
153 | } | |
154 | ||
155 | intermediate = intermediate->backing_hd; | |
156 | } | |
157 | ||
efcc7a23 | 158 | *pnum = n; |
c8c3080f MT |
159 | return 1; |
160 | } | |
161 | ||
4f1043b4 SH |
162 | static void coroutine_fn stream_run(void *opaque) |
163 | { | |
164 | StreamBlockJob *s = opaque; | |
165 | BlockDriverState *bs = s->common.bs; | |
c8c3080f | 166 | BlockDriverState *base = s->base; |
4f1043b4 SH |
167 | int64_t sector_num, end; |
168 | int ret = 0; | |
04120e3b | 169 | int n = 0; |
4f1043b4 SH |
170 | void *buf; |
171 | ||
172 | s->common.len = bdrv_getlength(bs); | |
173 | if (s->common.len < 0) { | |
174 | block_job_complete(&s->common, s->common.len); | |
175 | return; | |
176 | } | |
177 | ||
178 | end = s->common.len >> BDRV_SECTOR_BITS; | |
179 | buf = qemu_blockalign(bs, STREAM_BUFFER_SIZE); | |
180 | ||
181 | /* Turn on copy-on-read for the whole block device so that guest read | |
182 | * requests help us make progress. Only do this when copying the entire | |
183 | * backing chain since the copy-on-read operation does not take base into | |
184 | * account. | |
185 | */ | |
186 | if (!base) { | |
187 | bdrv_enable_copy_on_read(bs); | |
188 | } | |
189 | ||
190 | for (sector_num = 0; sector_num < end; sector_num += n) { | |
4513eafe PB |
191 | uint64_t delay_ns = 0; |
192 | ||
193 | wait: | |
194 | /* Note that even when no rate limit is applied we need to yield | |
195 | * with no pending I/O here so that qemu_aio_flush() returns. | |
196 | */ | |
197 | block_job_sleep_ns(&s->common, rt_clock, delay_ns); | |
4f1043b4 SH |
198 | if (block_job_is_cancelled(&s->common)) { |
199 | break; | |
200 | } | |
201 | ||
efcc7a23 PB |
202 | ret = is_allocated_base(bs, base, sector_num, |
203 | STREAM_BUFFER_SIZE / BDRV_SECTOR_SIZE, &n); | |
4f1043b4 SH |
204 | trace_stream_one_iteration(s, sector_num, n, ret); |
205 | if (ret == 0) { | |
5094a6c0 | 206 | if (s->common.speed) { |
4513eafe | 207 | delay_ns = ratelimit_calculate_delay(&s->limit, n); |
5094a6c0 | 208 | if (delay_ns > 0) { |
4513eafe | 209 | goto wait; |
5094a6c0 SH |
210 | } |
211 | } | |
4f1043b4 SH |
212 | ret = stream_populate(bs, sector_num, n, buf); |
213 | } | |
214 | if (ret < 0) { | |
215 | break; | |
216 | } | |
c8c3080f | 217 | ret = 0; |
4f1043b4 SH |
218 | |
219 | /* Publish progress */ | |
220 | s->common.offset += n * BDRV_SECTOR_SIZE; | |
221 | } | |
222 | ||
223 | if (!base) { | |
224 | bdrv_disable_copy_on_read(bs); | |
225 | } | |
226 | ||
3e914655 | 227 | if (!block_job_is_cancelled(&s->common) && sector_num == end && ret == 0) { |
f6133def | 228 | const char *base_id = NULL, *base_fmt = NULL; |
c8c3080f MT |
229 | if (base) { |
230 | base_id = s->backing_file_id; | |
f6133def PB |
231 | if (base->drv) { |
232 | base_fmt = base->drv->format_name; | |
233 | } | |
c8c3080f | 234 | } |
f6133def | 235 | ret = bdrv_change_backing_file(bs, base_id, base_fmt); |
5a67a104 | 236 | close_unused_images(bs, base, base_id); |
4f1043b4 SH |
237 | } |
238 | ||
239 | qemu_vfree(buf); | |
240 | block_job_complete(&s->common, ret); | |
241 | } | |
242 | ||
882ec7ce | 243 | static void stream_set_speed(BlockJob *job, int64_t speed, Error **errp) |
5094a6c0 SH |
244 | { |
245 | StreamBlockJob *s = container_of(job, StreamBlockJob, common); | |
246 | ||
882ec7ce SH |
247 | if (speed < 0) { |
248 | error_set(errp, QERR_INVALID_PARAMETER, "speed"); | |
9e6636c7 | 249 | return; |
5094a6c0 | 250 | } |
882ec7ce | 251 | ratelimit_set_speed(&s->limit, speed / BDRV_SECTOR_SIZE); |
5094a6c0 SH |
252 | } |
253 | ||
4f1043b4 SH |
254 | static BlockJobType stream_job_type = { |
255 | .instance_size = sizeof(StreamBlockJob), | |
256 | .job_type = "stream", | |
5094a6c0 | 257 | .set_speed = stream_set_speed, |
4f1043b4 SH |
258 | }; |
259 | ||
fd7f8c65 | 260 | void stream_start(BlockDriverState *bs, BlockDriverState *base, |
c83c66c3 SH |
261 | const char *base_id, int64_t speed, |
262 | BlockDriverCompletionFunc *cb, | |
fd7f8c65 | 263 | void *opaque, Error **errp) |
4f1043b4 SH |
264 | { |
265 | StreamBlockJob *s; | |
4f1043b4 | 266 | |
c83c66c3 | 267 | s = block_job_create(&stream_job_type, bs, speed, cb, opaque, errp); |
4f1043b4 | 268 | if (!s) { |
fd7f8c65 | 269 | return; |
4f1043b4 SH |
270 | } |
271 | ||
272 | s->base = base; | |
c8c3080f MT |
273 | if (base_id) { |
274 | pstrcpy(s->backing_file_id, sizeof(s->backing_file_id), base_id); | |
275 | } | |
4f1043b4 | 276 | |
fa4478d5 PB |
277 | s->common.co = qemu_coroutine_create(stream_run); |
278 | trace_stream_start(bs, base, s, s->common.co, opaque); | |
279 | qemu_coroutine_enter(s->common.co, s); | |
4f1043b4 | 280 | } |