This is the first step towards creating an infrastructure for generic background jobs that aren't tied to a block device. For now, Job only stores its ID and JobDriver, the rest stays in BlockJob. The following patches will move over more parts of BlockJob to Job if they are meaningful outside the context of a block job. BlockJob.driver is now redundant, but this patch leaves it around to avoid unnecessary churn. The next patches will get rid of almost all of its uses anyway so that it can be removed later with much less churn. Signed-off-by: Kevin Wolf <kwolf@redhat.com> Reviewed-by: Max Reitz <mreitz@redhat.com> Reviewed-by: John Snow <jsnow@redhat.com>
536 lines
16 KiB
C
536 lines
16 KiB
C
/*
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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 "qemu/osdep.h"
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#include "qemu/cutils.h"
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#include "trace.h"
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#include "block/block_int.h"
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#include "block/blockjob_int.h"
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#include "qapi/error.h"
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#include "qapi/qmp/qerror.h"
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#include "qemu/ratelimit.h"
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#include "sysemu/block-backend.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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typedef struct CommitBlockJob {
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BlockJob common;
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BlockDriverState *commit_top_bs;
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BlockBackend *top;
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BlockBackend *base;
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BlockdevOnError on_error;
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int base_flags;
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char *backing_file_str;
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} CommitBlockJob;
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static int coroutine_fn commit_populate(BlockBackend *bs, BlockBackend *base,
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int64_t offset, uint64_t bytes,
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void *buf)
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{
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int ret = 0;
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QEMUIOVector qiov;
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struct iovec iov = {
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.iov_base = buf,
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.iov_len = bytes,
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};
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assert(bytes < SIZE_MAX);
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qemu_iovec_init_external(&qiov, &iov, 1);
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ret = blk_co_preadv(bs, offset, qiov.size, &qiov, 0);
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if (ret < 0) {
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return ret;
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}
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ret = blk_co_pwritev(base, offset, qiov.size, &qiov, 0);
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if (ret < 0) {
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return ret;
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}
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return 0;
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}
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typedef struct {
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int ret;
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} CommitCompleteData;
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static void commit_complete(BlockJob *job, void *opaque)
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{
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CommitBlockJob *s = container_of(job, CommitBlockJob, common);
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CommitCompleteData *data = opaque;
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BlockDriverState *top = blk_bs(s->top);
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BlockDriverState *base = blk_bs(s->base);
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BlockDriverState *commit_top_bs = s->commit_top_bs;
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int ret = data->ret;
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bool remove_commit_top_bs = false;
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/* Make sure commit_top_bs and top stay around until bdrv_replace_node() */
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bdrv_ref(top);
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bdrv_ref(commit_top_bs);
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/* Remove base node parent that still uses BLK_PERM_WRITE/RESIZE before
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* the normal backing chain can be restored. */
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blk_unref(s->base);
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if (!block_job_is_cancelled(&s->common) && ret == 0) {
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/* success */
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ret = bdrv_drop_intermediate(s->commit_top_bs, base,
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s->backing_file_str);
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} else {
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/* XXX Can (or should) we somehow keep 'consistent read' blocked even
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* after the failed/cancelled commit job is gone? If we already wrote
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* something to base, the intermediate images aren't valid any more. */
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remove_commit_top_bs = true;
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}
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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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g_free(s->backing_file_str);
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blk_unref(s->top);
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/* If there is more than one reference to the job (e.g. if called from
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* block_job_finish_sync()), block_job_completed() won't free it and
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* therefore the blockers on the intermediate nodes remain. This would
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* cause bdrv_set_backing_hd() to fail. */
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block_job_remove_all_bdrv(job);
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block_job_completed(&s->common, ret);
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g_free(data);
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/* If bdrv_drop_intermediate() didn't already do that, remove the commit
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* filter driver from the backing chain. Do this as the final step so that
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* the 'consistent read' permission can be granted. */
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if (remove_commit_top_bs) {
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bdrv_child_try_set_perm(commit_top_bs->backing, 0, BLK_PERM_ALL,
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&error_abort);
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bdrv_replace_node(commit_top_bs, backing_bs(commit_top_bs),
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&error_abort);
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}
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bdrv_unref(commit_top_bs);
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bdrv_unref(top);
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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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CommitCompleteData *data;
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int64_t offset;
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uint64_t delay_ns = 0;
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int ret = 0;
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int64_t n = 0; /* bytes */
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void *buf = NULL;
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int bytes_written = 0;
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int64_t len, base_len;
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ret = len = blk_getlength(s->top);
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if (len < 0) {
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goto out;
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}
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block_job_progress_set_remaining(&s->common, len);
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ret = base_len = blk_getlength(s->base);
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if (base_len < 0) {
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goto out;
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}
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if (base_len < len) {
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ret = blk_truncate(s->base, len, PREALLOC_MODE_OFF, NULL);
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if (ret) {
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goto out;
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}
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}
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buf = blk_blockalign(s->top, COMMIT_BUFFER_SIZE);
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for (offset = 0; offset < len; offset += n) {
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bool copy;
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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, 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_is_allocated_above(blk_bs(s->top), blk_bs(s->base),
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offset, COMMIT_BUFFER_SIZE, &n);
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copy = (ret == 1);
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trace_commit_one_iteration(s, offset, n, ret);
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if (copy) {
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ret = commit_populate(s->top, s->base, offset, n, buf);
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bytes_written += n;
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}
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if (ret < 0) {
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BlockErrorAction action =
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block_job_error_action(&s->common, false, s->on_error, -ret);
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if (action == BLOCK_ERROR_ACTION_REPORT) {
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goto out;
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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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block_job_progress_update(&s->common, n);
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if (copy) {
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delay_ns = block_job_ratelimit_get_delay(&s->common, n);
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} else {
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delay_ns = 0;
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}
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}
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ret = 0;
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out:
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qemu_vfree(buf);
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data = g_malloc(sizeof(*data));
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data->ret = ret;
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block_job_defer_to_main_loop(&s->common, commit_complete, data);
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}
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static const BlockJobDriver commit_job_driver = {
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.job_driver = {
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.instance_size = sizeof(CommitBlockJob),
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},
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.job_type = BLOCK_JOB_TYPE_COMMIT,
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.start = commit_run,
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};
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static int coroutine_fn bdrv_commit_top_preadv(BlockDriverState *bs,
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uint64_t offset, uint64_t bytes, QEMUIOVector *qiov, int flags)
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{
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return bdrv_co_preadv(bs->backing, offset, bytes, qiov, flags);
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}
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static void bdrv_commit_top_refresh_filename(BlockDriverState *bs, QDict *opts)
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{
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bdrv_refresh_filename(bs->backing->bs);
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pstrcpy(bs->exact_filename, sizeof(bs->exact_filename),
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bs->backing->bs->filename);
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}
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static void bdrv_commit_top_close(BlockDriverState *bs)
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{
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}
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static void bdrv_commit_top_child_perm(BlockDriverState *bs, BdrvChild *c,
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const BdrvChildRole *role,
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BlockReopenQueue *reopen_queue,
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uint64_t perm, uint64_t shared,
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uint64_t *nperm, uint64_t *nshared)
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{
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*nperm = 0;
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*nshared = BLK_PERM_ALL;
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}
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/* Dummy node that provides consistent read to its users without requiring it
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* from its backing file and that allows writes on the backing file chain. */
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static BlockDriver bdrv_commit_top = {
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.format_name = "commit_top",
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.bdrv_co_preadv = bdrv_commit_top_preadv,
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.bdrv_co_block_status = bdrv_co_block_status_from_backing,
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.bdrv_refresh_filename = bdrv_commit_top_refresh_filename,
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.bdrv_close = bdrv_commit_top_close,
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.bdrv_child_perm = bdrv_commit_top_child_perm,
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};
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void commit_start(const char *job_id, BlockDriverState *bs,
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BlockDriverState *base, BlockDriverState *top, int64_t speed,
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BlockdevOnError on_error, const char *backing_file_str,
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const char *filter_node_name, Error **errp)
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{
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CommitBlockJob *s;
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int orig_base_flags;
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BlockDriverState *iter;
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BlockDriverState *commit_top_bs = NULL;
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Error *local_err = NULL;
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int ret;
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assert(top != bs);
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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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s = block_job_create(job_id, &commit_job_driver, NULL, bs, 0, BLK_PERM_ALL,
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speed, BLOCK_JOB_DEFAULT, NULL, NULL, errp);
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if (!s) {
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return;
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}
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/* convert base to r/w, if necessary */
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orig_base_flags = bdrv_get_flags(base);
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if (!(orig_base_flags & BDRV_O_RDWR)) {
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bdrv_reopen(base, orig_base_flags | BDRV_O_RDWR, &local_err);
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if (local_err != NULL) {
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error_propagate(errp, local_err);
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goto fail;
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}
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}
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/* Insert commit_top block node above top, so we can block consistent read
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* on the backing chain below it */
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commit_top_bs = bdrv_new_open_driver(&bdrv_commit_top, filter_node_name, 0,
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errp);
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if (commit_top_bs == NULL) {
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goto fail;
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}
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if (!filter_node_name) {
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commit_top_bs->implicit = true;
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}
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commit_top_bs->total_sectors = top->total_sectors;
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bdrv_set_aio_context(commit_top_bs, bdrv_get_aio_context(top));
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bdrv_set_backing_hd(commit_top_bs, top, &local_err);
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if (local_err) {
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bdrv_unref(commit_top_bs);
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commit_top_bs = NULL;
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error_propagate(errp, local_err);
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goto fail;
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}
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bdrv_replace_node(top, commit_top_bs, &local_err);
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if (local_err) {
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bdrv_unref(commit_top_bs);
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commit_top_bs = NULL;
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error_propagate(errp, local_err);
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goto fail;
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}
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s->commit_top_bs = commit_top_bs;
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bdrv_unref(commit_top_bs);
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/* Block all nodes between top and base, because they will
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* disappear from the chain after this operation. */
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assert(bdrv_chain_contains(top, base));
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for (iter = top; iter != base; iter = backing_bs(iter)) {
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/* XXX BLK_PERM_WRITE needs to be allowed so we don't block ourselves
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* at s->base (if writes are blocked for a node, they are also blocked
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* for its backing file). The other options would be a second filter
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* driver above s->base. */
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ret = block_job_add_bdrv(&s->common, "intermediate node", iter, 0,
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BLK_PERM_WRITE_UNCHANGED | BLK_PERM_WRITE,
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errp);
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if (ret < 0) {
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goto fail;
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}
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}
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ret = block_job_add_bdrv(&s->common, "base", base, 0, BLK_PERM_ALL, errp);
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if (ret < 0) {
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goto fail;
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}
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s->base = blk_new(BLK_PERM_CONSISTENT_READ
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| BLK_PERM_WRITE
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| BLK_PERM_RESIZE,
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BLK_PERM_CONSISTENT_READ
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| BLK_PERM_GRAPH_MOD
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| BLK_PERM_WRITE_UNCHANGED);
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ret = blk_insert_bs(s->base, base, errp);
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if (ret < 0) {
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goto fail;
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}
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/* Required permissions are already taken with block_job_add_bdrv() */
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s->top = blk_new(0, BLK_PERM_ALL);
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ret = blk_insert_bs(s->top, top, errp);
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if (ret < 0) {
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goto fail;
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}
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s->base_flags = orig_base_flags;
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s->backing_file_str = g_strdup(backing_file_str);
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s->on_error = on_error;
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trace_commit_start(bs, base, top, s);
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block_job_start(&s->common);
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return;
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fail:
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if (s->base) {
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blk_unref(s->base);
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}
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if (s->top) {
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blk_unref(s->top);
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}
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if (commit_top_bs) {
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bdrv_replace_node(commit_top_bs, top, &error_abort);
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}
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block_job_early_fail(&s->common);
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}
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#define COMMIT_BUF_SIZE (2048 * BDRV_SECTOR_SIZE)
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/* commit COW file into the raw image */
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int bdrv_commit(BlockDriverState *bs)
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{
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BlockBackend *src, *backing;
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BlockDriverState *backing_file_bs = NULL;
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BlockDriverState *commit_top_bs = NULL;
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BlockDriver *drv = bs->drv;
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int64_t offset, length, backing_length;
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int ro, open_flags;
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int64_t n;
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int ret = 0;
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uint8_t *buf = NULL;
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Error *local_err = NULL;
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if (!drv)
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return -ENOMEDIUM;
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if (!bs->backing) {
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return -ENOTSUP;
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}
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if (bdrv_op_is_blocked(bs, BLOCK_OP_TYPE_COMMIT_SOURCE, NULL) ||
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bdrv_op_is_blocked(bs->backing->bs, BLOCK_OP_TYPE_COMMIT_TARGET, NULL)) {
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return -EBUSY;
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}
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ro = bs->backing->bs->read_only;
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open_flags = bs->backing->bs->open_flags;
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if (ro) {
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if (bdrv_reopen(bs->backing->bs, open_flags | BDRV_O_RDWR, NULL)) {
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return -EACCES;
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}
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}
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src = blk_new(BLK_PERM_CONSISTENT_READ, BLK_PERM_ALL);
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backing = blk_new(BLK_PERM_WRITE | BLK_PERM_RESIZE, BLK_PERM_ALL);
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ret = blk_insert_bs(src, bs, &local_err);
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if (ret < 0) {
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error_report_err(local_err);
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goto ro_cleanup;
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}
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/* Insert commit_top block node above backing, so we can write to it */
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backing_file_bs = backing_bs(bs);
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commit_top_bs = bdrv_new_open_driver(&bdrv_commit_top, NULL, BDRV_O_RDWR,
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&local_err);
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if (commit_top_bs == NULL) {
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error_report_err(local_err);
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goto ro_cleanup;
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}
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bdrv_set_aio_context(commit_top_bs, bdrv_get_aio_context(backing_file_bs));
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bdrv_set_backing_hd(commit_top_bs, backing_file_bs, &error_abort);
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bdrv_set_backing_hd(bs, commit_top_bs, &error_abort);
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ret = blk_insert_bs(backing, backing_file_bs, &local_err);
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if (ret < 0) {
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error_report_err(local_err);
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goto ro_cleanup;
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}
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length = blk_getlength(src);
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if (length < 0) {
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ret = length;
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goto ro_cleanup;
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}
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backing_length = blk_getlength(backing);
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if (backing_length < 0) {
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ret = backing_length;
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goto ro_cleanup;
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}
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/* If our top snapshot is larger than the backing file image,
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* grow the backing file image if possible. If not possible,
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* we must return an error */
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if (length > backing_length) {
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ret = blk_truncate(backing, length, PREALLOC_MODE_OFF, &local_err);
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if (ret < 0) {
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error_report_err(local_err);
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goto ro_cleanup;
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}
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}
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/* blk_try_blockalign() for src will choose an alignment that works for
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* backing as well, so no need to compare the alignment manually. */
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buf = blk_try_blockalign(src, COMMIT_BUF_SIZE);
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if (buf == NULL) {
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ret = -ENOMEM;
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goto ro_cleanup;
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}
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for (offset = 0; offset < length; offset += n) {
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ret = bdrv_is_allocated(bs, offset, COMMIT_BUF_SIZE, &n);
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if (ret < 0) {
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goto ro_cleanup;
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}
|
|
if (ret) {
|
|
ret = blk_pread(src, offset, buf, n);
|
|
if (ret < 0) {
|
|
goto ro_cleanup;
|
|
}
|
|
|
|
ret = blk_pwrite(backing, offset, buf, n, 0);
|
|
if (ret < 0) {
|
|
goto ro_cleanup;
|
|
}
|
|
}
|
|
}
|
|
|
|
if (drv->bdrv_make_empty) {
|
|
ret = drv->bdrv_make_empty(bs);
|
|
if (ret < 0) {
|
|
goto ro_cleanup;
|
|
}
|
|
blk_flush(src);
|
|
}
|
|
|
|
/*
|
|
* Make sure all data we wrote to the backing device is actually
|
|
* stable on disk.
|
|
*/
|
|
blk_flush(backing);
|
|
|
|
ret = 0;
|
|
ro_cleanup:
|
|
qemu_vfree(buf);
|
|
|
|
blk_unref(backing);
|
|
if (backing_file_bs) {
|
|
bdrv_set_backing_hd(bs, backing_file_bs, &error_abort);
|
|
}
|
|
bdrv_unref(commit_top_bs);
|
|
blk_unref(src);
|
|
|
|
if (ro) {
|
|
/* ignoring error return here */
|
|
bdrv_reopen(bs->backing->bs, open_flags & ~BDRV_O_RDWR, NULL);
|
|
}
|
|
|
|
return ret;
|
|
}
|