/*
* 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;
char *backing_file_str;
} 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, s->backing_file_str);
}
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);
}
g_free(s->backing_file_str);
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, BlockCompletionFunc *cb,
void *opaque, const char *backing_file_str, 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_setg(errp, "Invalid parameter combination");
return;
}
assert(top != bs);
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->backing_file_str = g_strdup(backing_file_str);
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);
}
