root / block / commit.c @ 737e150e
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/*
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* Live block commit
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*
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* Copyright Red Hat, Inc. 2012
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*
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* Authors:
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* Jeff Cody <jcody@redhat.com>
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* Based on stream.c by Stefan Hajnoczi
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*
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* This work is licensed under the terms of the GNU LGPL, version 2 or later.
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* See the COPYING.LIB file in the top-level directory.
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*
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*/
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#include "trace.h" |
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#include "block/block_int.h" |
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#include "block/blockjob.h" |
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#include "qemu/ratelimit.h" |
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enum {
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/*
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* Size of data buffer for populating the image file. This should be large
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* enough to process multiple clusters in a single call, so that populating
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* contiguous regions of the image is efficient.
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*/
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COMMIT_BUFFER_SIZE = 512 * 1024, /* in bytes */ |
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}; |
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#define SLICE_TIME 100000000ULL /* ns */ |
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typedef struct CommitBlockJob { |
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BlockJob common; |
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RateLimit limit; |
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BlockDriverState *active; |
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BlockDriverState *top; |
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BlockDriverState *base; |
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BlockdevOnError on_error; |
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int base_flags;
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int orig_overlay_flags;
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} CommitBlockJob; |
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static int coroutine_fn commit_populate(BlockDriverState *bs, |
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BlockDriverState *base, |
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int64_t sector_num, int nb_sectors,
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void *buf)
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{ |
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int ret = 0; |
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ret = bdrv_read(bs, sector_num, buf, nb_sectors); |
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if (ret) {
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return ret;
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} |
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ret = bdrv_write(base, sector_num, buf, nb_sectors); |
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if (ret) {
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return ret;
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} |
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return 0; |
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} |
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static void coroutine_fn commit_run(void *opaque) |
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{ |
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CommitBlockJob *s = opaque; |
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BlockDriverState *active = s->active; |
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BlockDriverState *top = s->top; |
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BlockDriverState *base = s->base; |
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BlockDriverState *overlay_bs = NULL;
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int64_t sector_num, end; |
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int ret = 0; |
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int n = 0; |
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void *buf;
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int bytes_written = 0; |
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int64_t base_len; |
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ret = s->common.len = bdrv_getlength(top); |
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if (s->common.len < 0) { |
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goto exit_restore_reopen;
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} |
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ret = base_len = bdrv_getlength(base); |
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if (base_len < 0) { |
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goto exit_restore_reopen;
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} |
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if (base_len < s->common.len) {
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ret = bdrv_truncate(base, s->common.len); |
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if (ret) {
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goto exit_restore_reopen;
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} |
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} |
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overlay_bs = bdrv_find_overlay(active, top); |
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end = s->common.len >> BDRV_SECTOR_BITS; |
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buf = qemu_blockalign(top, COMMIT_BUFFER_SIZE); |
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for (sector_num = 0; sector_num < end; sector_num += n) { |
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uint64_t delay_ns = 0;
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bool copy;
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wait:
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/* Note that even when no rate limit is applied we need to yield
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* with no pending I/O here so that bdrv_drain_all() returns.
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*/
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block_job_sleep_ns(&s->common, rt_clock, delay_ns); |
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if (block_job_is_cancelled(&s->common)) {
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break;
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} |
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/* Copy if allocated above the base */
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ret = bdrv_co_is_allocated_above(top, base, sector_num, |
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COMMIT_BUFFER_SIZE / BDRV_SECTOR_SIZE, |
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&n); |
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copy = (ret == 1);
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trace_commit_one_iteration(s, sector_num, n, ret); |
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if (copy) {
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if (s->common.speed) {
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delay_ns = ratelimit_calculate_delay(&s->limit, n); |
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if (delay_ns > 0) { |
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goto wait;
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} |
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} |
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ret = commit_populate(top, base, sector_num, n, buf); |
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bytes_written += n * BDRV_SECTOR_SIZE; |
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} |
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if (ret < 0) { |
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if (s->on_error == BLOCKDEV_ON_ERROR_STOP ||
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s->on_error == BLOCKDEV_ON_ERROR_REPORT|| |
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(s->on_error == BLOCKDEV_ON_ERROR_ENOSPC && ret == -ENOSPC)) { |
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goto exit_free_buf;
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} else {
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n = 0;
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continue;
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} |
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} |
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/* Publish progress */
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s->common.offset += n * BDRV_SECTOR_SIZE; |
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} |
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ret = 0;
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if (!block_job_is_cancelled(&s->common) && sector_num == end) {
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/* success */
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ret = bdrv_drop_intermediate(active, top, base); |
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} |
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exit_free_buf:
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qemu_vfree(buf); |
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exit_restore_reopen:
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/* restore base open flags here if appropriate (e.g., change the base back
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* to r/o). These reopens do not need to be atomic, since we won't abort
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* even on failure here */
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if (s->base_flags != bdrv_get_flags(base)) {
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bdrv_reopen(base, s->base_flags, NULL);
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} |
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if (s->orig_overlay_flags != bdrv_get_flags(overlay_bs)) {
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bdrv_reopen(overlay_bs, s->orig_overlay_flags, NULL);
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} |
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block_job_completed(&s->common, ret); |
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} |
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static void commit_set_speed(BlockJob *job, int64_t speed, Error **errp) |
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{ |
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CommitBlockJob *s = container_of(job, CommitBlockJob, common); |
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if (speed < 0) { |
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error_set(errp, QERR_INVALID_PARAMETER, "speed");
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return;
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} |
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ratelimit_set_speed(&s->limit, speed / BDRV_SECTOR_SIZE, SLICE_TIME); |
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} |
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static BlockJobType commit_job_type = {
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.instance_size = sizeof(CommitBlockJob),
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.job_type = "commit",
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.set_speed = commit_set_speed, |
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}; |
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void commit_start(BlockDriverState *bs, BlockDriverState *base,
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BlockDriverState *top, int64_t speed, |
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BlockdevOnError on_error, BlockDriverCompletionFunc *cb, |
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void *opaque, Error **errp)
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{ |
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CommitBlockJob *s; |
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BlockReopenQueue *reopen_queue = NULL;
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int orig_overlay_flags;
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int orig_base_flags;
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BlockDriverState *overlay_bs; |
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Error *local_err = NULL;
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if ((on_error == BLOCKDEV_ON_ERROR_STOP ||
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on_error == BLOCKDEV_ON_ERROR_ENOSPC) && |
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!bdrv_iostatus_is_enabled(bs)) { |
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error_set(errp, QERR_INVALID_PARAMETER_COMBINATION); |
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return;
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} |
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/* Once we support top == active layer, remove this check */
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if (top == bs) {
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error_setg(errp, |
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"Top image as the active layer is currently unsupported");
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return;
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} |
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if (top == base) {
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error_setg(errp, "Invalid files for merge: top and base are the same");
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return;
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} |
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overlay_bs = bdrv_find_overlay(bs, top); |
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if (overlay_bs == NULL) { |
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error_setg(errp, "Could not find overlay image for %s:", top->filename);
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return;
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} |
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orig_base_flags = bdrv_get_flags(base); |
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orig_overlay_flags = bdrv_get_flags(overlay_bs); |
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/* convert base & overlay_bs to r/w, if necessary */
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if (!(orig_base_flags & BDRV_O_RDWR)) {
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reopen_queue = bdrv_reopen_queue(reopen_queue, base, |
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orig_base_flags | BDRV_O_RDWR); |
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} |
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if (!(orig_overlay_flags & BDRV_O_RDWR)) {
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reopen_queue = bdrv_reopen_queue(reopen_queue, overlay_bs, |
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orig_overlay_flags | BDRV_O_RDWR); |
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} |
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if (reopen_queue) {
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bdrv_reopen_multiple(reopen_queue, &local_err); |
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if (local_err != NULL) { |
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error_propagate(errp, local_err); |
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return;
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} |
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} |
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s = block_job_create(&commit_job_type, bs, speed, cb, opaque, errp); |
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if (!s) {
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return;
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} |
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s->base = base; |
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s->top = top; |
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s->active = bs; |
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s->base_flags = orig_base_flags; |
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s->orig_overlay_flags = orig_overlay_flags; |
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s->on_error = on_error; |
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s->common.co = qemu_coroutine_create(commit_run); |
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trace_commit_start(bs, base, top, s, s->common.co, opaque); |
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qemu_coroutine_enter(s->common.co, s); |
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} |