usb-bsd: convert to QOM
[qemu.git] / block / stream.c
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
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
56 typedef struct StreamBlockJob {
57 BlockJob common;
58 RateLimit limit;
59 BlockDriverState *base;
60 char backing_file_id[1024];
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
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
144 static void coroutine_fn stream_run(void *opaque)
145 {
146 StreamBlockJob *s = opaque;
147 BlockDriverState *bs = s->common.bs;
148 BlockDriverState *base = s->base;
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) {
173 retry:
174 if (block_job_is_cancelled(&s->common)) {
175 break;
176 }
177
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 }
187 trace_stream_one_iteration(s, sector_num, n, ret);
188 if (ret == 0) {
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 }
198 ret = stream_populate(bs, sector_num, n, buf);
199 }
200 if (ret < 0) {
201 break;
202 }
203 ret = 0;
204
205 /* Publish progress */
206 s->common.offset += n * BDRV_SECTOR_SIZE;
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);
212 }
213
214 if (!base) {
215 bdrv_disable_copy_on_read(bs);
216 }
217
218 if (sector_num == end && ret == 0) {
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);
224 }
225
226 qemu_vfree(buf);
227 block_job_complete(&s->common, ret);
228 }
229
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
242 static BlockJobType stream_job_type = {
243 .instance_size = sizeof(StreamBlockJob),
244 .job_type = "stream",
245 .set_speed = stream_set_speed,
246 };
247
248 int stream_start(BlockDriverState *bs, BlockDriverState *base,
249 const char *base_id, BlockDriverCompletionFunc *cb,
250 void *opaque)
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;
261 if (base_id) {
262 pstrcpy(s->backing_file_id, sizeof(s->backing_file_id), base_id);
263 }
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 }