vhost-user-scsi: use glib allocation
[qemu/ar7.git] / block / stream.c
blobe6f72346e56750112b1a81539dd22d3503011a78
1 /*
2 * Image streaming
4 * Copyright IBM, Corp. 2011
6 * Authors:
7 * Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
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.
14 #include "qemu/osdep.h"
15 #include "trace.h"
16 #include "block/block_int.h"
17 #include "block/blockjob_int.h"
18 #include "qapi/error.h"
19 #include "qapi/qmp/qerror.h"
20 #include "qemu/ratelimit.h"
21 #include "sysemu/block-backend.h"
23 enum {
25 * Size of data buffer for populating the image file. This should be large
26 * enough to process multiple clusters in a single call, so that populating
27 * contiguous regions of the image is efficient.
29 STREAM_BUFFER_SIZE = 512 * 1024, /* in bytes */
32 #define SLICE_TIME 100000000ULL /* ns */
34 typedef struct StreamBlockJob {
35 BlockJob common;
36 RateLimit limit;
37 BlockDriverState *base;
38 BlockdevOnError on_error;
39 char *backing_file_str;
40 int bs_flags;
41 } StreamBlockJob;
43 static int coroutine_fn stream_populate(BlockBackend *blk,
44 int64_t offset, uint64_t bytes,
45 void *buf)
47 struct iovec iov = {
48 .iov_base = buf,
49 .iov_len = bytes,
51 QEMUIOVector qiov;
53 assert(bytes < SIZE_MAX);
54 qemu_iovec_init_external(&qiov, &iov, 1);
56 /* Copy-on-read the unallocated clusters */
57 return blk_co_preadv(blk, offset, qiov.size, &qiov, BDRV_REQ_COPY_ON_READ);
60 typedef struct {
61 int ret;
62 } StreamCompleteData;
64 static void stream_complete(BlockJob *job, void *opaque)
66 StreamBlockJob *s = container_of(job, StreamBlockJob, common);
67 StreamCompleteData *data = opaque;
68 BlockDriverState *bs = blk_bs(job->blk);
69 BlockDriverState *base = s->base;
70 Error *local_err = NULL;
72 if (!block_job_is_cancelled(&s->common) && bs->backing &&
73 data->ret == 0) {
74 const char *base_id = NULL, *base_fmt = NULL;
75 if (base) {
76 base_id = s->backing_file_str;
77 if (base->drv) {
78 base_fmt = base->drv->format_name;
81 data->ret = bdrv_change_backing_file(bs, base_id, base_fmt);
82 bdrv_set_backing_hd(bs, base, &local_err);
83 if (local_err) {
84 error_report_err(local_err);
85 data->ret = -EPERM;
86 goto out;
90 out:
91 /* Reopen the image back in read-only mode if necessary */
92 if (s->bs_flags != bdrv_get_flags(bs)) {
93 /* Give up write permissions before making it read-only */
94 blk_set_perm(job->blk, 0, BLK_PERM_ALL, &error_abort);
95 bdrv_reopen(bs, s->bs_flags, NULL);
98 g_free(s->backing_file_str);
99 block_job_completed(&s->common, data->ret);
100 g_free(data);
103 static void coroutine_fn stream_run(void *opaque)
105 StreamBlockJob *s = opaque;
106 StreamCompleteData *data;
107 BlockBackend *blk = s->common.blk;
108 BlockDriverState *bs = blk_bs(blk);
109 BlockDriverState *base = s->base;
110 int64_t offset = 0;
111 uint64_t delay_ns = 0;
112 int error = 0;
113 int ret = 0;
114 int64_t n = 0; /* bytes */
115 void *buf;
117 if (!bs->backing) {
118 goto out;
121 s->common.len = bdrv_getlength(bs);
122 if (s->common.len < 0) {
123 ret = s->common.len;
124 goto out;
127 buf = qemu_blockalign(bs, STREAM_BUFFER_SIZE);
129 /* Turn on copy-on-read for the whole block device so that guest read
130 * requests help us make progress. Only do this when copying the entire
131 * backing chain since the copy-on-read operation does not take base into
132 * account.
134 if (!base) {
135 bdrv_enable_copy_on_read(bs);
138 for ( ; offset < s->common.len; offset += n) {
139 bool copy;
141 /* Note that even when no rate limit is applied we need to yield
142 * with no pending I/O here so that bdrv_drain_all() returns.
144 block_job_sleep_ns(&s->common, QEMU_CLOCK_REALTIME, delay_ns);
145 if (block_job_is_cancelled(&s->common)) {
146 break;
149 copy = false;
151 ret = bdrv_is_allocated(bs, offset, STREAM_BUFFER_SIZE, &n);
152 if (ret == 1) {
153 /* Allocated in the top, no need to copy. */
154 } else if (ret >= 0) {
155 /* Copy if allocated in the intermediate images. Limit to the
156 * known-unallocated area [offset, offset+n*BDRV_SECTOR_SIZE). */
157 ret = bdrv_is_allocated_above(backing_bs(bs), base,
158 offset, n, &n);
160 /* Finish early if end of backing file has been reached */
161 if (ret == 0 && n == 0) {
162 n = s->common.len - offset;
165 copy = (ret == 1);
167 trace_stream_one_iteration(s, offset, n, ret);
168 if (copy) {
169 ret = stream_populate(blk, offset, n, buf);
171 if (ret < 0) {
172 BlockErrorAction action =
173 block_job_error_action(&s->common, s->on_error, true, -ret);
174 if (action == BLOCK_ERROR_ACTION_STOP) {
175 n = 0;
176 continue;
178 if (error == 0) {
179 error = ret;
181 if (action == BLOCK_ERROR_ACTION_REPORT) {
182 break;
185 ret = 0;
187 /* Publish progress */
188 s->common.offset += n;
189 if (copy && s->common.speed) {
190 delay_ns = ratelimit_calculate_delay(&s->limit, n);
194 if (!base) {
195 bdrv_disable_copy_on_read(bs);
198 /* Do not remove the backing file if an error was there but ignored. */
199 ret = error;
201 qemu_vfree(buf);
203 out:
204 /* Modify backing chain and close BDSes in main loop */
205 data = g_malloc(sizeof(*data));
206 data->ret = ret;
207 block_job_defer_to_main_loop(&s->common, stream_complete, data);
210 static void stream_set_speed(BlockJob *job, int64_t speed, Error **errp)
212 StreamBlockJob *s = container_of(job, StreamBlockJob, common);
214 if (speed < 0) {
215 error_setg(errp, QERR_INVALID_PARAMETER, "speed");
216 return;
218 ratelimit_set_speed(&s->limit, speed, SLICE_TIME);
221 static const BlockJobDriver stream_job_driver = {
222 .instance_size = sizeof(StreamBlockJob),
223 .job_type = BLOCK_JOB_TYPE_STREAM,
224 .set_speed = stream_set_speed,
225 .start = stream_run,
228 void stream_start(const char *job_id, BlockDriverState *bs,
229 BlockDriverState *base, const char *backing_file_str,
230 int64_t speed, BlockdevOnError on_error, Error **errp)
232 StreamBlockJob *s;
233 BlockDriverState *iter;
234 int orig_bs_flags;
236 /* Make sure that the image is opened in read-write mode */
237 orig_bs_flags = bdrv_get_flags(bs);
238 if (!(orig_bs_flags & BDRV_O_RDWR)) {
239 if (bdrv_reopen(bs, orig_bs_flags | BDRV_O_RDWR, errp) != 0) {
240 return;
244 /* Prevent concurrent jobs trying to modify the graph structure here, we
245 * already have our own plans. Also don't allow resize as the image size is
246 * queried only at the job start and then cached. */
247 s = block_job_create(job_id, &stream_job_driver, bs,
248 BLK_PERM_CONSISTENT_READ | BLK_PERM_WRITE_UNCHANGED |
249 BLK_PERM_GRAPH_MOD,
250 BLK_PERM_CONSISTENT_READ | BLK_PERM_WRITE_UNCHANGED |
251 BLK_PERM_WRITE,
252 speed, BLOCK_JOB_DEFAULT, NULL, NULL, errp);
253 if (!s) {
254 goto fail;
257 /* Block all intermediate nodes between bs and base, because they will
258 * disappear from the chain after this operation. The streaming job reads
259 * every block only once, assuming that it doesn't change, so block writes
260 * and resizes. */
261 for (iter = backing_bs(bs); iter && iter != base; iter = backing_bs(iter)) {
262 block_job_add_bdrv(&s->common, "intermediate node", iter, 0,
263 BLK_PERM_CONSISTENT_READ | BLK_PERM_WRITE_UNCHANGED,
264 &error_abort);
267 s->base = base;
268 s->backing_file_str = g_strdup(backing_file_str);
269 s->bs_flags = orig_bs_flags;
271 s->on_error = on_error;
272 trace_stream_start(bs, base, s);
273 block_job_start(&s->common);
274 return;
276 fail:
277 if (orig_bs_flags != bdrv_get_flags(bs)) {
278 bdrv_reopen(bs, orig_bs_flags, NULL);