485 lines
15 KiB
C
485 lines
15 KiB
C
/*
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* QEMU backup
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*
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* Copyright (C) 2013 Proxmox Server Solutions
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* Copyright (c) 2019 Virtuozzo International GmbH.
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*
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* Authors:
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* Dietmar Maurer (dietmar@proxmox.com)
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*
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* This work is licensed under the terms of the GNU GPL, version 2 or later.
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* See the COPYING 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 "trace.h"
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#include "block/block.h"
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#include "block/block_int.h"
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#include "block/blockjob_int.h"
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#include "block/block_backup.h"
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#include "block/block-copy.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 "qemu/cutils.h"
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#include "sysemu/block-backend.h"
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#include "qemu/bitmap.h"
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#include "qemu/error-report.h"
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#include "block/backup-top.h"
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#define BACKUP_CLUSTER_SIZE_DEFAULT (1 << 16)
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typedef struct BackupBlockJob {
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BlockJob common;
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BlockDriverState *backup_top;
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BlockDriverState *source_bs;
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BdrvDirtyBitmap *sync_bitmap;
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MirrorSyncMode sync_mode;
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BitmapSyncMode bitmap_mode;
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BlockdevOnError on_source_error;
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BlockdevOnError on_target_error;
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uint64_t len;
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uint64_t bytes_read;
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int64_t cluster_size;
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BlockCopyState *bcs;
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} BackupBlockJob;
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static const BlockJobDriver backup_job_driver;
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static void backup_progress_bytes_callback(int64_t bytes, void *opaque)
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{
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BackupBlockJob *s = opaque;
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s->bytes_read += bytes;
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}
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static int coroutine_fn backup_do_cow(BackupBlockJob *job,
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int64_t offset, uint64_t bytes,
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bool *error_is_read)
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{
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int ret = 0;
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int64_t start, end; /* bytes */
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start = QEMU_ALIGN_DOWN(offset, job->cluster_size);
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end = QEMU_ALIGN_UP(bytes + offset, job->cluster_size);
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trace_backup_do_cow_enter(job, start, offset, bytes);
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ret = block_copy(job->bcs, start, end - start, error_is_read);
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trace_backup_do_cow_return(job, offset, bytes, ret);
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return ret;
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}
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static void backup_cleanup_sync_bitmap(BackupBlockJob *job, int ret)
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{
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BdrvDirtyBitmap *bm;
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bool sync = (((ret == 0) || (job->bitmap_mode == BITMAP_SYNC_MODE_ALWAYS)) \
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&& (job->bitmap_mode != BITMAP_SYNC_MODE_NEVER));
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if (sync) {
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/*
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* We succeeded, or we always intended to sync the bitmap.
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* Delete this bitmap and install the child.
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*/
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bm = bdrv_dirty_bitmap_abdicate(job->sync_bitmap, NULL);
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} else {
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/*
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* We failed, or we never intended to sync the bitmap anyway.
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* Merge the successor back into the parent, keeping all data.
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*/
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bm = bdrv_reclaim_dirty_bitmap(job->sync_bitmap, NULL);
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}
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assert(bm);
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if (ret < 0 && job->bitmap_mode == BITMAP_SYNC_MODE_ALWAYS) {
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/* If we failed and synced, merge in the bits we didn't copy: */
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bdrv_dirty_bitmap_merge_internal(bm, block_copy_dirty_bitmap(job->bcs),
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NULL, true);
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}
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}
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static void backup_commit(Job *job)
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{
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BackupBlockJob *s = container_of(job, BackupBlockJob, common.job);
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if (s->sync_bitmap) {
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backup_cleanup_sync_bitmap(s, 0);
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}
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}
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static void backup_abort(Job *job)
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{
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BackupBlockJob *s = container_of(job, BackupBlockJob, common.job);
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if (s->sync_bitmap) {
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backup_cleanup_sync_bitmap(s, -1);
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}
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}
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static void backup_clean(Job *job)
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{
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BackupBlockJob *s = container_of(job, BackupBlockJob, common.job);
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bdrv_backup_top_drop(s->backup_top);
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}
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void backup_do_checkpoint(BlockJob *job, Error **errp)
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{
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BackupBlockJob *backup_job = container_of(job, BackupBlockJob, common);
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assert(block_job_driver(job) == &backup_job_driver);
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if (backup_job->sync_mode != MIRROR_SYNC_MODE_NONE) {
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error_setg(errp, "The backup job only supports block checkpoint in"
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" sync=none mode");
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return;
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}
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bdrv_set_dirty_bitmap(block_copy_dirty_bitmap(backup_job->bcs), 0,
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backup_job->len);
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}
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static BlockErrorAction backup_error_action(BackupBlockJob *job,
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bool read, int error)
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{
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if (read) {
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return block_job_error_action(&job->common, job->on_source_error,
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true, error);
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} else {
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return block_job_error_action(&job->common, job->on_target_error,
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false, error);
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}
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}
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static bool coroutine_fn yield_and_check(BackupBlockJob *job)
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{
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uint64_t delay_ns;
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if (job_is_cancelled(&job->common.job)) {
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return true;
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}
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/*
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* We need to yield even for delay_ns = 0 so that bdrv_drain_all() can
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* return. Without a yield, the VM would not reboot.
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*/
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delay_ns = block_job_ratelimit_get_delay(&job->common, job->bytes_read);
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job->bytes_read = 0;
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job_sleep_ns(&job->common.job, delay_ns);
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if (job_is_cancelled(&job->common.job)) {
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return true;
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}
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return false;
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}
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static int coroutine_fn backup_loop(BackupBlockJob *job)
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{
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bool error_is_read;
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int64_t offset;
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BdrvDirtyBitmapIter *bdbi;
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int ret = 0;
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bdbi = bdrv_dirty_iter_new(block_copy_dirty_bitmap(job->bcs));
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while ((offset = bdrv_dirty_iter_next(bdbi)) != -1) {
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do {
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if (yield_and_check(job)) {
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goto out;
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}
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ret = backup_do_cow(job, offset, job->cluster_size, &error_is_read);
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if (ret < 0 && backup_error_action(job, error_is_read, -ret) ==
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BLOCK_ERROR_ACTION_REPORT)
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{
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goto out;
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}
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} while (ret < 0);
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}
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out:
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bdrv_dirty_iter_free(bdbi);
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return ret;
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}
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static void backup_init_bcs_bitmap(BackupBlockJob *job)
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{
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bool ret;
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uint64_t estimate;
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BdrvDirtyBitmap *bcs_bitmap = block_copy_dirty_bitmap(job->bcs);
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if (job->sync_mode == MIRROR_SYNC_MODE_BITMAP) {
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ret = bdrv_dirty_bitmap_merge_internal(bcs_bitmap, job->sync_bitmap,
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NULL, true);
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assert(ret);
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} else {
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if (job->sync_mode == MIRROR_SYNC_MODE_TOP) {
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/*
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* We can't hog the coroutine to initialize this thoroughly.
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* Set a flag and resume work when we are able to yield safely.
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*/
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block_copy_set_skip_unallocated(job->bcs, true);
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}
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bdrv_set_dirty_bitmap(bcs_bitmap, 0, job->len);
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}
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estimate = bdrv_get_dirty_count(bcs_bitmap);
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job_progress_set_remaining(&job->common.job, estimate);
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}
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static int coroutine_fn backup_run(Job *job, Error **errp)
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{
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BackupBlockJob *s = container_of(job, BackupBlockJob, common.job);
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int ret = 0;
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backup_init_bcs_bitmap(s);
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if (s->sync_mode == MIRROR_SYNC_MODE_TOP) {
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int64_t offset = 0;
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int64_t count;
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for (offset = 0; offset < s->len; ) {
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if (yield_and_check(s)) {
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ret = -ECANCELED;
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goto out;
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}
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ret = block_copy_reset_unallocated(s->bcs, offset, &count);
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if (ret < 0) {
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goto out;
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}
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offset += count;
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}
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block_copy_set_skip_unallocated(s->bcs, false);
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}
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if (s->sync_mode == MIRROR_SYNC_MODE_NONE) {
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/*
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* All bits are set in bcs bitmap to allow any cluster to be copied.
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* This does not actually require them to be copied.
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*/
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while (!job_is_cancelled(job)) {
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/*
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* Yield until the job is cancelled. We just let our before_write
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* notify callback service CoW requests.
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*/
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job_yield(job);
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}
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} else {
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ret = backup_loop(s);
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}
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out:
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return ret;
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}
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static const BlockJobDriver backup_job_driver = {
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.job_driver = {
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.instance_size = sizeof(BackupBlockJob),
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.job_type = JOB_TYPE_BACKUP,
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.free = block_job_free,
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.user_resume = block_job_user_resume,
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.run = backup_run,
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.commit = backup_commit,
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.abort = backup_abort,
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.clean = backup_clean,
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}
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};
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static int64_t backup_calculate_cluster_size(BlockDriverState *target,
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Error **errp)
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{
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int ret;
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BlockDriverInfo bdi;
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/*
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* If there is no backing file on the target, we cannot rely on COW if our
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* backup cluster size is smaller than the target cluster size. Even for
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* targets with a backing file, try to avoid COW if possible.
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*/
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ret = bdrv_get_info(target, &bdi);
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if (ret == -ENOTSUP && !target->backing) {
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/* Cluster size is not defined */
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warn_report("The target block device doesn't provide "
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"information about the block size and it doesn't have a "
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"backing file. The default block size of %u bytes is "
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"used. If the actual block size of the target exceeds "
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"this default, the backup may be unusable",
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BACKUP_CLUSTER_SIZE_DEFAULT);
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return BACKUP_CLUSTER_SIZE_DEFAULT;
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} else if (ret < 0 && !target->backing) {
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error_setg_errno(errp, -ret,
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"Couldn't determine the cluster size of the target image, "
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"which has no backing file");
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error_append_hint(errp,
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"Aborting, since this may create an unusable destination image\n");
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return ret;
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} else if (ret < 0 && target->backing) {
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/* Not fatal; just trudge on ahead. */
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return BACKUP_CLUSTER_SIZE_DEFAULT;
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}
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return MAX(BACKUP_CLUSTER_SIZE_DEFAULT, bdi.cluster_size);
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}
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BlockJob *backup_job_create(const char *job_id, BlockDriverState *bs,
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BlockDriverState *target, int64_t speed,
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MirrorSyncMode sync_mode, BdrvDirtyBitmap *sync_bitmap,
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BitmapSyncMode bitmap_mode,
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bool compress,
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const char *filter_node_name,
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BlockdevOnError on_source_error,
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BlockdevOnError on_target_error,
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int creation_flags,
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BlockCompletionFunc *cb, void *opaque,
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JobTxn *txn, Error **errp)
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{
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int64_t len, target_len;
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BackupBlockJob *job = NULL;
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int64_t cluster_size;
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BdrvRequestFlags write_flags;
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BlockDriverState *backup_top = NULL;
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BlockCopyState *bcs = NULL;
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assert(bs);
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assert(target);
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/* QMP interface protects us from these cases */
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assert(sync_mode != MIRROR_SYNC_MODE_INCREMENTAL);
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assert(sync_bitmap || sync_mode != MIRROR_SYNC_MODE_BITMAP);
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if (bs == target) {
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error_setg(errp, "Source and target cannot be the same");
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return NULL;
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}
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if (!bdrv_is_inserted(bs)) {
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error_setg(errp, "Device is not inserted: %s",
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bdrv_get_device_name(bs));
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return NULL;
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}
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if (!bdrv_is_inserted(target)) {
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error_setg(errp, "Device is not inserted: %s",
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bdrv_get_device_name(target));
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return NULL;
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}
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if (compress && !block_driver_can_compress(target->drv)) {
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error_setg(errp, "Compression is not supported for this drive %s",
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bdrv_get_device_name(target));
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return NULL;
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}
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if (bdrv_op_is_blocked(bs, BLOCK_OP_TYPE_BACKUP_SOURCE, errp)) {
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return NULL;
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}
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if (bdrv_op_is_blocked(target, BLOCK_OP_TYPE_BACKUP_TARGET, errp)) {
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return NULL;
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}
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if (sync_bitmap) {
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/* If we need to write to this bitmap, check that we can: */
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if (bitmap_mode != BITMAP_SYNC_MODE_NEVER &&
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bdrv_dirty_bitmap_check(sync_bitmap, BDRV_BITMAP_DEFAULT, errp)) {
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return NULL;
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}
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/* Create a new bitmap, and freeze/disable this one. */
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if (bdrv_dirty_bitmap_create_successor(sync_bitmap, errp) < 0) {
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return NULL;
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}
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}
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len = bdrv_getlength(bs);
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if (len < 0) {
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error_setg_errno(errp, -len, "Unable to get length for '%s'",
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bdrv_get_device_or_node_name(bs));
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goto error;
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}
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target_len = bdrv_getlength(target);
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if (target_len < 0) {
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error_setg_errno(errp, -target_len, "Unable to get length for '%s'",
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bdrv_get_device_or_node_name(bs));
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goto error;
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}
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if (target_len != len) {
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error_setg(errp, "Source and target image have different sizes");
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goto error;
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}
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cluster_size = backup_calculate_cluster_size(target, errp);
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if (cluster_size < 0) {
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goto error;
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}
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/*
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* If source is in backing chain of target assume that target is going to be
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* used for "image fleecing", i.e. it should represent a kind of snapshot of
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* source at backup-start point in time. And target is going to be read by
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* somebody (for example, used as NBD export) during backup job.
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*
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* In this case, we need to add BDRV_REQ_SERIALISING write flag to avoid
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* intersection of backup writes and third party reads from target,
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* otherwise reading from target we may occasionally read already updated by
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* guest data.
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*
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* For more information see commit f8d59dfb40bb and test
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* tests/qemu-iotests/222
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*/
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write_flags = (bdrv_chain_contains(target, bs) ? BDRV_REQ_SERIALISING : 0) |
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(compress ? BDRV_REQ_WRITE_COMPRESSED : 0),
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backup_top = bdrv_backup_top_append(bs, target, filter_node_name,
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cluster_size, write_flags, &bcs, errp);
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if (!backup_top) {
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goto error;
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}
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/* job->len is fixed, so we can't allow resize */
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job = block_job_create(job_id, &backup_job_driver, txn, backup_top,
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0, BLK_PERM_ALL,
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speed, creation_flags, cb, opaque, errp);
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if (!job) {
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goto error;
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}
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job->backup_top = backup_top;
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job->source_bs = bs;
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job->on_source_error = on_source_error;
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job->on_target_error = on_target_error;
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job->sync_mode = sync_mode;
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job->sync_bitmap = sync_bitmap;
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job->bitmap_mode = bitmap_mode;
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job->bcs = bcs;
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job->cluster_size = cluster_size;
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job->len = len;
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block_copy_set_progress_callback(bcs, backup_progress_bytes_callback, job);
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block_copy_set_progress_meter(bcs, &job->common.job.progress);
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/* Required permissions are already taken by backup-top target */
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block_job_add_bdrv(&job->common, "target", target, 0, BLK_PERM_ALL,
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&error_abort);
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return &job->common;
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error:
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if (sync_bitmap) {
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bdrv_reclaim_dirty_bitmap(sync_bitmap, NULL);
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}
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if (backup_top) {
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bdrv_backup_top_drop(backup_top);
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}
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return NULL;
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}
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