aboutsummaryrefslogtreecommitdiff
path: root/block/commit.c
blob: d4090cbf7de11ba9e6c8de3302ebaefeea55f901 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
/*
 * Live block commit
 *
 * Copyright Red Hat, Inc. 2012
 *
 * Authors:
 *  Jeff Cody   <jcody@redhat.com>
 *  Based on stream.c by Stefan Hajnoczi
 *
 * This work is licensed under the terms of the GNU LGPL, version 2 or later.
 * See the COPYING.LIB file in the top-level directory.
 *
 */

#include "trace.h"
#include "block/block_int.h"
#include "block/blockjob.h"
#include "qemu/ratelimit.h"

enum {
    /*
     * Size of data buffer for populating the image file.  This should be large
     * enough to process multiple clusters in a single call, so that populating
     * contiguous regions of the image is efficient.
     */
    COMMIT_BUFFER_SIZE = 512 * 1024, /* in bytes */
};

#define SLICE_TIME 100000000ULL /* ns */

typedef struct CommitBlockJob {
    BlockJob common;
    RateLimit limit;
    BlockDriverState *active;
    BlockDriverState *top;
    BlockDriverState *base;
    BlockdevOnError on_error;
    int base_flags;
    int orig_overlay_flags;
} CommitBlockJob;

static int coroutine_fn commit_populate(BlockDriverState *bs,
                                        BlockDriverState *base,
                                        int64_t sector_num, int nb_sectors,
                                        void *buf)
{
    int ret = 0;

    ret = bdrv_read(bs, sector_num, buf, nb_sectors);
    if (ret) {
        return ret;
    }

    ret = bdrv_write(base, sector_num, buf, nb_sectors);
    if (ret) {
        return ret;
    }

    return 0;
}

static void coroutine_fn commit_run(void *opaque)
{
    CommitBlockJob *s = opaque;
    BlockDriverState *active = s->active;
    BlockDriverState *top = s->top;
    BlockDriverState *base = s->base;
    BlockDriverState *overlay_bs;
    int64_t sector_num, end;
    int ret = 0;
    int n = 0;
    void *buf;
    int bytes_written = 0;
    int64_t base_len;

    ret = s->common.len = bdrv_getlength(top);


    if (s->common.len < 0) {
        goto exit_restore_reopen;
    }

    ret = base_len = bdrv_getlength(base);
    if (base_len < 0) {
        goto exit_restore_reopen;
    }

    if (base_len < s->common.len) {
        ret = bdrv_truncate(base, s->common.len);
        if (ret) {
            goto exit_restore_reopen;
        }
    }

    end = s->common.len >> BDRV_SECTOR_BITS;
    buf = qemu_blockalign(top, COMMIT_BUFFER_SIZE);

    for (sector_num = 0; sector_num < end; sector_num += n) {
        uint64_t delay_ns = 0;
        bool copy;

wait:
        /* Note that even when no rate limit is applied we need to yield
         * with no pending I/O here so that bdrv_drain_all() returns.
         */
        block_job_sleep_ns(&s->common, QEMU_CLOCK_REALTIME, delay_ns);
        if (block_job_is_cancelled(&s->common)) {
            break;
        }
        /* Copy if allocated above the base */
        ret = bdrv_is_allocated_above(top, base, sector_num,
                                      COMMIT_BUFFER_SIZE / BDRV_SECTOR_SIZE,
                                      &n);
        copy = (ret == 1);
        trace_commit_one_iteration(s, sector_num, n, ret);
        if (copy) {
            if (s->common.speed) {
                delay_ns = ratelimit_calculate_delay(&s->limit, n);
                if (delay_ns > 0) {
                    goto wait;
                }
            }
            ret = commit_populate(top, base, sector_num, n, buf);
            bytes_written += n * BDRV_SECTOR_SIZE;
        }
        if (ret < 0) {
            if (s->on_error == BLOCKDEV_ON_ERROR_STOP ||
                s->on_error == BLOCKDEV_ON_ERROR_REPORT||
                (s->on_error == BLOCKDEV_ON_ERROR_ENOSPC && ret == -ENOSPC)) {
                goto exit_free_buf;
            } else {
                n = 0;
                continue;
            }
        }
        /* Publish progress */
        s->common.offset += n * BDRV_SECTOR_SIZE;
    }

    ret = 0;

    if (!block_job_is_cancelled(&s->common) && sector_num == end) {
        /* success */
        ret = bdrv_drop_intermediate(active, top, base);
    }

exit_free_buf:
    qemu_vfree(buf);

exit_restore_reopen:
    /* restore base open flags here if appropriate (e.g., change the base back
     * to r/o). These reopens do not need to be atomic, since we won't abort
     * even on failure here */
    if (s->base_flags != bdrv_get_flags(base)) {
        bdrv_reopen(base, s->base_flags, NULL);
    }
    overlay_bs = bdrv_find_overlay(active, top);
    if (overlay_bs && s->orig_overlay_flags != bdrv_get_flags(overlay_bs)) {
        bdrv_reopen(overlay_bs, s->orig_overlay_flags, NULL);
    }

    block_job_completed(&s->common, ret);
}

static void commit_set_speed(BlockJob *job, int64_t speed, Error **errp)
{
    CommitBlockJob *s = container_of(job, CommitBlockJob, common);

    if (speed < 0) {
        error_set(errp, QERR_INVALID_PARAMETER, "speed");
        return;
    }
    ratelimit_set_speed(&s->limit, speed / BDRV_SECTOR_SIZE, SLICE_TIME);
}

static const BlockJobDriver commit_job_driver = {
    .instance_size = sizeof(CommitBlockJob),
    .job_type      = BLOCK_JOB_TYPE_COMMIT,
    .set_speed     = commit_set_speed,
};

void commit_start(BlockDriverState *bs, BlockDriverState *base,
                  BlockDriverState *top, int64_t speed,
                  BlockdevOnError on_error, BlockDriverCompletionFunc *cb,
                  void *opaque, Error **errp)
{
    CommitBlockJob *s;
    BlockReopenQueue *reopen_queue = NULL;
    int orig_overlay_flags;
    int orig_base_flags;
    BlockDriverState *overlay_bs;
    Error *local_err = NULL;

    if ((on_error == BLOCKDEV_ON_ERROR_STOP ||
         on_error == BLOCKDEV_ON_ERROR_ENOSPC) &&
        !bdrv_iostatus_is_enabled(bs)) {
        error_set(errp, QERR_INVALID_PARAMETER_COMBINATION);
        return;
    }

    /* Once we support top == active layer, remove this check */
    if (top == bs) {
        error_setg(errp,
                   "Top image as the active layer is currently unsupported");
        return;
    }

    if (top == base) {
        error_setg(errp, "Invalid files for merge: top and base are the same");
        return;
    }

    overlay_bs = bdrv_find_overlay(bs, top);

    if (overlay_bs == NULL) {
        error_setg(errp, "Could not find overlay image for %s:", top->filename);
        return;
    }

    orig_base_flags    = bdrv_get_flags(base);
    orig_overlay_flags = bdrv_get_flags(overlay_bs);

    /* convert base & overlay_bs to r/w, if necessary */
    if (!(orig_base_flags & BDRV_O_RDWR)) {
        reopen_queue = bdrv_reopen_queue(reopen_queue, base,
                                         orig_base_flags | BDRV_O_RDWR);
    }
    if (!(orig_overlay_flags & BDRV_O_RDWR)) {
        reopen_queue = bdrv_reopen_queue(reopen_queue, overlay_bs,
                                         orig_overlay_flags | BDRV_O_RDWR);
    }
    if (reopen_queue) {
        bdrv_reopen_multiple(reopen_queue, &local_err);
        if (local_err != NULL) {
            error_propagate(errp, local_err);
            return;
        }
    }


    s = block_job_create(&commit_job_driver, bs, speed, cb, opaque, errp);
    if (!s) {
        return;
    }

    s->base   = base;
    s->top    = top;
    s->active = bs;

    s->base_flags          = orig_base_flags;
    s->orig_overlay_flags  = orig_overlay_flags;

    s->on_error = on_error;
    s->common.co = qemu_coroutine_create(commit_run);

    trace_commit_start(bs, base, top, s, s->common.co, opaque);
    qemu_coroutine_enter(s->common.co, s);
}