667 lines
21 KiB
C
667 lines
21 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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*
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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.h"
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#include "block/block_backup.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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#define BACKUP_CLUSTER_SIZE_DEFAULT (1 << 16)
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#define SLICE_TIME 100000000ULL /* ns */
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typedef struct BackupBlockJob {
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BlockJob common;
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BlockBackend *target;
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/* bitmap for sync=incremental */
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BdrvDirtyBitmap *sync_bitmap;
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MirrorSyncMode sync_mode;
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RateLimit limit;
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BlockdevOnError on_source_error;
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BlockdevOnError on_target_error;
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CoRwlock flush_rwlock;
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uint64_t sectors_read;
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unsigned long *done_bitmap;
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int64_t cluster_size;
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bool compress;
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NotifierWithReturn before_write;
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QLIST_HEAD(, CowRequest) inflight_reqs;
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} BackupBlockJob;
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/* Size of a cluster in sectors, instead of bytes. */
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static inline int64_t cluster_size_sectors(BackupBlockJob *job)
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{
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return job->cluster_size / BDRV_SECTOR_SIZE;
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}
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/* See if in-flight requests overlap and wait for them to complete */
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static void coroutine_fn wait_for_overlapping_requests(BackupBlockJob *job,
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int64_t start,
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int64_t end)
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{
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CowRequest *req;
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bool retry;
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do {
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retry = false;
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QLIST_FOREACH(req, &job->inflight_reqs, list) {
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if (end > req->start && start < req->end) {
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qemu_co_queue_wait(&req->wait_queue);
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retry = true;
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break;
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}
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}
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} while (retry);
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}
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/* Keep track of an in-flight request */
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static void cow_request_begin(CowRequest *req, BackupBlockJob *job,
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int64_t start, int64_t end)
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{
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req->start = start;
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req->end = end;
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qemu_co_queue_init(&req->wait_queue);
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QLIST_INSERT_HEAD(&job->inflight_reqs, req, list);
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}
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/* Forget about a completed request */
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static void cow_request_end(CowRequest *req)
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{
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QLIST_REMOVE(req, list);
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qemu_co_queue_restart_all(&req->wait_queue);
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}
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static int coroutine_fn backup_do_cow(BackupBlockJob *job,
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int64_t sector_num, int nb_sectors,
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bool *error_is_read,
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bool is_write_notifier)
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{
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BlockBackend *blk = job->common.blk;
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CowRequest cow_request;
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struct iovec iov;
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QEMUIOVector bounce_qiov;
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void *bounce_buffer = NULL;
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int ret = 0;
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int64_t sectors_per_cluster = cluster_size_sectors(job);
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int64_t start, end;
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int n;
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qemu_co_rwlock_rdlock(&job->flush_rwlock);
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start = sector_num / sectors_per_cluster;
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end = DIV_ROUND_UP(sector_num + nb_sectors, sectors_per_cluster);
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trace_backup_do_cow_enter(job, start, sector_num, nb_sectors);
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wait_for_overlapping_requests(job, start, end);
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cow_request_begin(&cow_request, job, start, end);
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for (; start < end; start++) {
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if (test_bit(start, job->done_bitmap)) {
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trace_backup_do_cow_skip(job, start);
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continue; /* already copied */
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}
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trace_backup_do_cow_process(job, start);
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n = MIN(sectors_per_cluster,
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job->common.len / BDRV_SECTOR_SIZE -
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start * sectors_per_cluster);
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if (!bounce_buffer) {
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bounce_buffer = blk_blockalign(blk, job->cluster_size);
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}
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iov.iov_base = bounce_buffer;
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iov.iov_len = n * BDRV_SECTOR_SIZE;
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qemu_iovec_init_external(&bounce_qiov, &iov, 1);
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ret = blk_co_preadv(blk, start * job->cluster_size,
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bounce_qiov.size, &bounce_qiov,
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is_write_notifier ? BDRV_REQ_NO_SERIALISING : 0);
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if (ret < 0) {
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trace_backup_do_cow_read_fail(job, start, ret);
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if (error_is_read) {
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*error_is_read = true;
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}
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goto out;
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}
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if (buffer_is_zero(iov.iov_base, iov.iov_len)) {
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ret = blk_co_pwrite_zeroes(job->target, start * job->cluster_size,
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bounce_qiov.size, BDRV_REQ_MAY_UNMAP);
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} else {
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ret = blk_co_pwritev(job->target, start * job->cluster_size,
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bounce_qiov.size, &bounce_qiov,
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job->compress ? BDRV_REQ_WRITE_COMPRESSED : 0);
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}
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if (ret < 0) {
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trace_backup_do_cow_write_fail(job, start, ret);
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if (error_is_read) {
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*error_is_read = false;
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}
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goto out;
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}
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set_bit(start, job->done_bitmap);
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/* Publish progress, guest I/O counts as progress too. Note that the
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* offset field is an opaque progress value, it is not a disk offset.
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*/
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job->sectors_read += n;
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job->common.offset += n * BDRV_SECTOR_SIZE;
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}
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out:
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if (bounce_buffer) {
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qemu_vfree(bounce_buffer);
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}
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cow_request_end(&cow_request);
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trace_backup_do_cow_return(job, sector_num, nb_sectors, ret);
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qemu_co_rwlock_unlock(&job->flush_rwlock);
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return ret;
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}
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static int coroutine_fn backup_before_write_notify(
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NotifierWithReturn *notifier,
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void *opaque)
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{
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BackupBlockJob *job = container_of(notifier, BackupBlockJob, before_write);
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BdrvTrackedRequest *req = opaque;
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int64_t sector_num = req->offset >> BDRV_SECTOR_BITS;
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int nb_sectors = req->bytes >> BDRV_SECTOR_BITS;
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assert(req->bs == blk_bs(job->common.blk));
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assert((req->offset & (BDRV_SECTOR_SIZE - 1)) == 0);
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assert((req->bytes & (BDRV_SECTOR_SIZE - 1)) == 0);
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return backup_do_cow(job, sector_num, nb_sectors, NULL, true);
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}
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static void backup_set_speed(BlockJob *job, int64_t speed, Error **errp)
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{
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BackupBlockJob *s = container_of(job, BackupBlockJob, common);
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if (speed < 0) {
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error_setg(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 void backup_cleanup_sync_bitmap(BackupBlockJob *job, int ret)
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{
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BdrvDirtyBitmap *bm;
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BlockDriverState *bs = blk_bs(job->common.blk);
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if (ret < 0 || block_job_is_cancelled(&job->common)) {
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/* Merge the successor back into the parent, delete nothing. */
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bm = bdrv_reclaim_dirty_bitmap(bs, job->sync_bitmap, NULL);
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assert(bm);
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} else {
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/* Everything is fine, delete this bitmap and install the backup. */
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bm = bdrv_dirty_bitmap_abdicate(bs, job->sync_bitmap, NULL);
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assert(bm);
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}
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}
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static void backup_commit(BlockJob *job)
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{
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BackupBlockJob *s = container_of(job, BackupBlockJob, common);
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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(BlockJob *job)
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{
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BackupBlockJob *s = container_of(job, BackupBlockJob, common);
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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_attached_aio_context(BlockJob *job, AioContext *aio_context)
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{
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BackupBlockJob *s = container_of(job, BackupBlockJob, common);
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blk_set_aio_context(s->target, aio_context);
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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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int64_t len;
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assert(job->driver->job_type == BLOCK_JOB_TYPE_BACKUP);
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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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len = DIV_ROUND_UP(backup_job->common.len, backup_job->cluster_size);
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bitmap_zero(backup_job->done_bitmap, len);
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}
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void backup_wait_for_overlapping_requests(BlockJob *job, int64_t sector_num,
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int nb_sectors)
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{
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BackupBlockJob *backup_job = container_of(job, BackupBlockJob, common);
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int64_t sectors_per_cluster = cluster_size_sectors(backup_job);
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int64_t start, end;
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assert(job->driver->job_type == BLOCK_JOB_TYPE_BACKUP);
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start = sector_num / sectors_per_cluster;
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end = DIV_ROUND_UP(sector_num + nb_sectors, sectors_per_cluster);
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wait_for_overlapping_requests(backup_job, start, end);
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}
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void backup_cow_request_begin(CowRequest *req, BlockJob *job,
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int64_t sector_num,
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int nb_sectors)
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{
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BackupBlockJob *backup_job = container_of(job, BackupBlockJob, common);
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int64_t sectors_per_cluster = cluster_size_sectors(backup_job);
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int64_t start, end;
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assert(job->driver->job_type == BLOCK_JOB_TYPE_BACKUP);
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start = sector_num / sectors_per_cluster;
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end = DIV_ROUND_UP(sector_num + nb_sectors, sectors_per_cluster);
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cow_request_begin(req, backup_job, start, end);
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}
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void backup_cow_request_end(CowRequest *req)
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{
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cow_request_end(req);
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}
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static void backup_drain(BlockJob *job)
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{
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BackupBlockJob *s = container_of(job, BackupBlockJob, common);
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/* Need to keep a reference in case blk_drain triggers execution
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* of backup_complete...
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*/
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if (s->target) {
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BlockBackend *target = s->target;
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blk_ref(target);
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blk_drain(target);
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blk_unref(target);
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}
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}
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static const BlockJobDriver backup_job_driver = {
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.instance_size = sizeof(BackupBlockJob),
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.job_type = BLOCK_JOB_TYPE_BACKUP,
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.set_speed = backup_set_speed,
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.commit = backup_commit,
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.abort = backup_abort,
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.attached_aio_context = backup_attached_aio_context,
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.drain = backup_drain,
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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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typedef struct {
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int ret;
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} BackupCompleteData;
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static void backup_complete(BlockJob *job, void *opaque)
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{
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BackupBlockJob *s = container_of(job, BackupBlockJob, common);
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BackupCompleteData *data = opaque;
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blk_unref(s->target);
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s->target = NULL;
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block_job_completed(job, data->ret);
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g_free(data);
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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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if (block_job_is_cancelled(&job->common)) {
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return true;
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}
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/* we need to yield so that bdrv_drain_all() returns.
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* (without, VM does not reboot)
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*/
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if (job->common.speed) {
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uint64_t delay_ns = ratelimit_calculate_delay(&job->limit,
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job->sectors_read);
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job->sectors_read = 0;
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block_job_sleep_ns(&job->common, QEMU_CLOCK_REALTIME, delay_ns);
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} else {
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block_job_sleep_ns(&job->common, QEMU_CLOCK_REALTIME, 0);
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}
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if (block_job_is_cancelled(&job->common)) {
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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_run_incremental(BackupBlockJob *job)
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{
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bool error_is_read;
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int ret = 0;
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int clusters_per_iter;
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uint32_t granularity;
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int64_t sector;
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int64_t cluster;
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int64_t end;
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int64_t last_cluster = -1;
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int64_t sectors_per_cluster = cluster_size_sectors(job);
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BdrvDirtyBitmapIter *dbi;
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granularity = bdrv_dirty_bitmap_granularity(job->sync_bitmap);
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clusters_per_iter = MAX((granularity / job->cluster_size), 1);
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dbi = bdrv_dirty_iter_new(job->sync_bitmap, 0);
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/* Find the next dirty sector(s) */
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while ((sector = bdrv_dirty_iter_next(dbi)) != -1) {
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cluster = sector / sectors_per_cluster;
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/* Fake progress updates for any clusters we skipped */
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if (cluster != last_cluster + 1) {
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job->common.offset += ((cluster - last_cluster - 1) *
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job->cluster_size);
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}
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for (end = cluster + clusters_per_iter; cluster < end; cluster++) {
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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, cluster * sectors_per_cluster,
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sectors_per_cluster, &error_is_read,
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false);
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if ((ret < 0) &&
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backup_error_action(job, error_is_read, -ret) ==
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BLOCK_ERROR_ACTION_REPORT) {
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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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/* If the bitmap granularity is smaller than the backup granularity,
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* we need to advance the iterator pointer to the next cluster. */
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if (granularity < job->cluster_size) {
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bdrv_set_dirty_iter(dbi, cluster * sectors_per_cluster);
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}
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last_cluster = cluster - 1;
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}
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/* Play some final catchup with the progress meter */
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end = DIV_ROUND_UP(job->common.len, job->cluster_size);
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if (last_cluster + 1 < end) {
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job->common.offset += ((end - last_cluster - 1) * job->cluster_size);
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}
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out:
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bdrv_dirty_iter_free(dbi);
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return ret;
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}
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static void coroutine_fn backup_run(void *opaque)
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{
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BackupBlockJob *job = opaque;
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BackupCompleteData *data;
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BlockDriverState *bs = blk_bs(job->common.blk);
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BlockBackend *target = job->target;
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int64_t start, end;
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int64_t sectors_per_cluster = cluster_size_sectors(job);
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int ret = 0;
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QLIST_INIT(&job->inflight_reqs);
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qemu_co_rwlock_init(&job->flush_rwlock);
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start = 0;
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end = DIV_ROUND_UP(job->common.len, job->cluster_size);
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job->done_bitmap = bitmap_new(end);
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job->before_write.notify = backup_before_write_notify;
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bdrv_add_before_write_notifier(bs, &job->before_write);
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if (job->sync_mode == MIRROR_SYNC_MODE_NONE) {
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while (!block_job_is_cancelled(&job->common)) {
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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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block_job_yield(&job->common);
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}
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} else if (job->sync_mode == MIRROR_SYNC_MODE_INCREMENTAL) {
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ret = backup_run_incremental(job);
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} else {
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/* Both FULL and TOP SYNC_MODE's require copying.. */
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for (; start < end; start++) {
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bool error_is_read;
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if (yield_and_check(job)) {
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break;
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}
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if (job->sync_mode == MIRROR_SYNC_MODE_TOP) {
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int i, n;
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int alloced = 0;
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/* Check to see if these blocks are already in the
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* backing file. */
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for (i = 0; i < sectors_per_cluster;) {
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/* bdrv_is_allocated() only returns true/false based
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* on the first set of sectors it comes across that
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* are are all in the same state.
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* For that reason we must verify each sector in the
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* backup cluster length. We end up copying more than
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* needed but at some point that is always the case. */
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alloced =
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bdrv_is_allocated(bs,
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start * sectors_per_cluster + i,
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sectors_per_cluster - i, &n);
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i += n;
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if (alloced == 1 || n == 0) {
|
|
break;
|
|
}
|
|
}
|
|
|
|
/* If the above loop never found any sectors that are in
|
|
* the topmost image, skip this backup. */
|
|
if (alloced == 0) {
|
|
continue;
|
|
}
|
|
}
|
|
/* FULL sync mode we copy the whole drive. */
|
|
ret = backup_do_cow(job, start * sectors_per_cluster,
|
|
sectors_per_cluster, &error_is_read, false);
|
|
if (ret < 0) {
|
|
/* Depending on error action, fail now or retry cluster */
|
|
BlockErrorAction action =
|
|
backup_error_action(job, error_is_read, -ret);
|
|
if (action == BLOCK_ERROR_ACTION_REPORT) {
|
|
break;
|
|
} else {
|
|
start--;
|
|
continue;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
notifier_with_return_remove(&job->before_write);
|
|
|
|
/* wait until pending backup_do_cow() calls have completed */
|
|
qemu_co_rwlock_wrlock(&job->flush_rwlock);
|
|
qemu_co_rwlock_unlock(&job->flush_rwlock);
|
|
g_free(job->done_bitmap);
|
|
|
|
bdrv_op_unblock_all(blk_bs(target), job->common.blocker);
|
|
|
|
data = g_malloc(sizeof(*data));
|
|
data->ret = ret;
|
|
block_job_defer_to_main_loop(&job->common, backup_complete, data);
|
|
}
|
|
|
|
void backup_start(const char *job_id, BlockDriverState *bs,
|
|
BlockDriverState *target, int64_t speed,
|
|
MirrorSyncMode sync_mode, BdrvDirtyBitmap *sync_bitmap,
|
|
bool compress,
|
|
BlockdevOnError on_source_error,
|
|
BlockdevOnError on_target_error,
|
|
BlockCompletionFunc *cb, void *opaque,
|
|
BlockJobTxn *txn, Error **errp)
|
|
{
|
|
int64_t len;
|
|
BlockDriverInfo bdi;
|
|
BackupBlockJob *job = NULL;
|
|
int ret;
|
|
|
|
assert(bs);
|
|
assert(target);
|
|
|
|
if (bs == target) {
|
|
error_setg(errp, "Source and target cannot be the same");
|
|
return;
|
|
}
|
|
|
|
if (!bdrv_is_inserted(bs)) {
|
|
error_setg(errp, "Device is not inserted: %s",
|
|
bdrv_get_device_name(bs));
|
|
return;
|
|
}
|
|
|
|
if (!bdrv_is_inserted(target)) {
|
|
error_setg(errp, "Device is not inserted: %s",
|
|
bdrv_get_device_name(target));
|
|
return;
|
|
}
|
|
|
|
if (compress && target->drv->bdrv_co_pwritev_compressed == NULL) {
|
|
error_setg(errp, "Compression is not supported for this drive %s",
|
|
bdrv_get_device_name(target));
|
|
return;
|
|
}
|
|
|
|
if (bdrv_op_is_blocked(bs, BLOCK_OP_TYPE_BACKUP_SOURCE, errp)) {
|
|
return;
|
|
}
|
|
|
|
if (bdrv_op_is_blocked(target, BLOCK_OP_TYPE_BACKUP_TARGET, errp)) {
|
|
return;
|
|
}
|
|
|
|
if (sync_mode == MIRROR_SYNC_MODE_INCREMENTAL) {
|
|
if (!sync_bitmap) {
|
|
error_setg(errp, "must provide a valid bitmap name for "
|
|
"\"incremental\" sync mode");
|
|
return;
|
|
}
|
|
|
|
/* Create a new bitmap, and freeze/disable this one. */
|
|
if (bdrv_dirty_bitmap_create_successor(bs, sync_bitmap, errp) < 0) {
|
|
return;
|
|
}
|
|
} else if (sync_bitmap) {
|
|
error_setg(errp,
|
|
"a sync_bitmap was provided to backup_run, "
|
|
"but received an incompatible sync_mode (%s)",
|
|
MirrorSyncMode_lookup[sync_mode]);
|
|
return;
|
|
}
|
|
|
|
len = bdrv_getlength(bs);
|
|
if (len < 0) {
|
|
error_setg_errno(errp, -len, "unable to get length for '%s'",
|
|
bdrv_get_device_name(bs));
|
|
goto error;
|
|
}
|
|
|
|
job = block_job_create(job_id, &backup_job_driver, bs, speed,
|
|
cb, opaque, errp);
|
|
if (!job) {
|
|
goto error;
|
|
}
|
|
|
|
job->target = blk_new();
|
|
blk_insert_bs(job->target, target);
|
|
|
|
job->on_source_error = on_source_error;
|
|
job->on_target_error = on_target_error;
|
|
job->sync_mode = sync_mode;
|
|
job->sync_bitmap = sync_mode == MIRROR_SYNC_MODE_INCREMENTAL ?
|
|
sync_bitmap : NULL;
|
|
job->compress = compress;
|
|
|
|
/* If there is no backing file on the target, we cannot rely on COW if our
|
|
* backup cluster size is smaller than the target cluster size. Even for
|
|
* targets with a backing file, try to avoid COW if possible. */
|
|
ret = bdrv_get_info(target, &bdi);
|
|
if (ret < 0 && !target->backing) {
|
|
error_setg_errno(errp, -ret,
|
|
"Couldn't determine the cluster size of the target image, "
|
|
"which has no backing file");
|
|
error_append_hint(errp,
|
|
"Aborting, since this may create an unusable destination image\n");
|
|
goto error;
|
|
} else if (ret < 0 && target->backing) {
|
|
/* Not fatal; just trudge on ahead. */
|
|
job->cluster_size = BACKUP_CLUSTER_SIZE_DEFAULT;
|
|
} else {
|
|
job->cluster_size = MAX(BACKUP_CLUSTER_SIZE_DEFAULT, bdi.cluster_size);
|
|
}
|
|
|
|
bdrv_op_block_all(target, job->common.blocker);
|
|
job->common.len = len;
|
|
job->common.co = qemu_coroutine_create(backup_run, job);
|
|
block_job_txn_add_job(txn, &job->common);
|
|
qemu_coroutine_enter(job->common.co);
|
|
return;
|
|
|
|
error:
|
|
if (sync_bitmap) {
|
|
bdrv_reclaim_dirty_bitmap(bs, sync_bitmap, NULL);
|
|
}
|
|
if (job) {
|
|
blk_unref(job->target);
|
|
block_job_unref(&job->common);
|
|
}
|
|
}
|