/* * QEMU backup * * Copyright (C) 2013 Proxmox Server Solutions * * Authors: * Dietmar Maurer (dietmar@proxmox.com) * * This work is licensed under the terms of the GNU GPL, version 2 or later. * See the COPYING file in the top-level directory. * */ #include <stdio.h> #include <errno.h> #include <unistd.h> #include "trace.h" #include "block/block.h" #include "block/block_int.h" #include "block/blockjob.h" #include "qemu/ratelimit.h" #define BACKUP_CLUSTER_BITS 16 #define BACKUP_CLUSTER_SIZE (1 << BACKUP_CLUSTER_BITS) #define BACKUP_SECTORS_PER_CLUSTER (BACKUP_CLUSTER_SIZE / BDRV_SECTOR_SIZE) #define SLICE_TIME 100000000ULL /* ns */ typedef struct CowRequest { int64_t start; int64_t end; QLIST_ENTRY(CowRequest) list; CoQueue wait_queue; /* coroutines blocked on this request */ } CowRequest; typedef struct BackupBlockJob { BlockJob common; BlockDriverState *target; MirrorSyncMode sync_mode; RateLimit limit; BlockdevOnError on_source_error; BlockdevOnError on_target_error; CoRwlock flush_rwlock; uint64_t sectors_read; HBitmap *bitmap; QLIST_HEAD(, CowRequest) inflight_reqs; } BackupBlockJob; /* See if in-flight requests overlap and wait for them to complete */ static void coroutine_fn wait_for_overlapping_requests(BackupBlockJob *job, int64_t start, int64_t end) { CowRequest *req; bool retry; do { retry = false; QLIST_FOREACH(req, &job->inflight_reqs, list) { if (end > req->start && start < req->end) { qemu_co_queue_wait(&req->wait_queue); retry = true; break; } } } while (retry); } /* Keep track of an in-flight request */ static void cow_request_begin(CowRequest *req, BackupBlockJob *job, int64_t start, int64_t end) { req->start = start; req->end = end; qemu_co_queue_init(&req->wait_queue); QLIST_INSERT_HEAD(&job->inflight_reqs, req, list); } /* Forget about a completed request */ static void cow_request_end(CowRequest *req) { QLIST_REMOVE(req, list); qemu_co_queue_restart_all(&req->wait_queue); } static int coroutine_fn backup_do_cow(BlockDriverState *bs, int64_t sector_num, int nb_sectors, bool *error_is_read) { BackupBlockJob *job = (BackupBlockJob *)bs->job; CowRequest cow_request; struct iovec iov; QEMUIOVector bounce_qiov; void *bounce_buffer = NULL; int ret = 0; int64_t start, end; int n; qemu_co_rwlock_rdlock(&job->flush_rwlock); start = sector_num / BACKUP_SECTORS_PER_CLUSTER; end = DIV_ROUND_UP(sector_num + nb_sectors, BACKUP_SECTORS_PER_CLUSTER); trace_backup_do_cow_enter(job, start, sector_num, nb_sectors); wait_for_overlapping_requests(job, start, end); cow_request_begin(&cow_request, job, start, end); for (; start < end; start++) { if (hbitmap_get(job->bitmap, start)) { trace_backup_do_cow_skip(job, start); continue; /* already copied */ } trace_backup_do_cow_process(job, start); n = MIN(BACKUP_SECTORS_PER_CLUSTER, job->common.len / BDRV_SECTOR_SIZE - start * BACKUP_SECTORS_PER_CLUSTER); if (!bounce_buffer) { bounce_buffer = qemu_blockalign(bs, BACKUP_CLUSTER_SIZE); } iov.iov_base = bounce_buffer; iov.iov_len = n * BDRV_SECTOR_SIZE; qemu_iovec_init_external(&bounce_qiov, &iov, 1); ret = bdrv_co_readv(bs, start * BACKUP_SECTORS_PER_CLUSTER, n, &bounce_qiov); if (ret < 0) { trace_backup_do_cow_read_fail(job, start, ret); if (error_is_read) { *error_is_read = true; } goto out; } if (buffer_is_zero(iov.iov_base, iov.iov_len)) { ret = bdrv_co_write_zeroes(job->target, start * BACKUP_SECTORS_PER_CLUSTER, n, BDRV_REQ_MAY_UNMAP); } else { ret = bdrv_co_writev(job->target, start * BACKUP_SECTORS_PER_CLUSTER, n, &bounce_qiov); } if (ret < 0) { trace_backup_do_cow_write_fail(job, start, ret); if (error_is_read) { *error_is_read = false; } goto out; } hbitmap_set(job->bitmap, start, 1); /* Publish progress, guest I/O counts as progress too. Note that the * offset field is an opaque progress value, it is not a disk offset. */ job->sectors_read += n; job->common.offset += n * BDRV_SECTOR_SIZE; } out: if (bounce_buffer) { qemu_vfree(bounce_buffer); } cow_request_end(&cow_request); trace_backup_do_cow_return(job, sector_num, nb_sectors, ret); qemu_co_rwlock_unlock(&job->flush_rwlock); return ret; } static int coroutine_fn backup_before_write_notify( NotifierWithReturn *notifier, void *opaque) { BdrvTrackedRequest *req = opaque; int64_t sector_num = req->offset >> BDRV_SECTOR_BITS; int nb_sectors = req->bytes >> BDRV_SECTOR_BITS; assert((req->offset & (BDRV_SECTOR_SIZE - 1)) == 0); assert((req->bytes & (BDRV_SECTOR_SIZE - 1)) == 0); return backup_do_cow(req->bs, sector_num, nb_sectors, NULL); } static void backup_set_speed(BlockJob *job, int64_t speed, Error **errp) { BackupBlockJob *s = container_of(job, BackupBlockJob, common); if (speed < 0) { error_set(errp, QERR_INVALID_PARAMETER, "speed"); return; } ratelimit_set_speed(&s->limit, speed / BDRV_SECTOR_SIZE, SLICE_TIME); } static void backup_iostatus_reset(BlockJob *job) { BackupBlockJob *s = container_of(job, BackupBlockJob, common); bdrv_iostatus_reset(s->target); } static const BlockJobDriver backup_job_driver = { .instance_size = sizeof(BackupBlockJob), .job_type = BLOCK_JOB_TYPE_BACKUP, .set_speed = backup_set_speed, .iostatus_reset = backup_iostatus_reset, }; static BlockErrorAction backup_error_action(BackupBlockJob *job, bool read, int error) { if (read) { return block_job_error_action(&job->common, job->common.bs, job->on_source_error, true, error); } else { return block_job_error_action(&job->common, job->target, job->on_target_error, false, error); } } typedef struct { int ret; } BackupCompleteData; static void backup_complete(BlockJob *job, void *opaque) { BackupBlockJob *s = container_of(job, BackupBlockJob, common); BackupCompleteData *data = opaque; bdrv_unref(s->target); block_job_completed(job, data->ret); g_free(data); } static void coroutine_fn backup_run(void *opaque) { BackupBlockJob *job = opaque; BackupCompleteData *data; BlockDriverState *bs = job->common.bs; BlockDriverState *target = job->target; BlockdevOnError on_target_error = job->on_target_error; NotifierWithReturn before_write = { .notify = backup_before_write_notify, }; int64_t start, end; int ret = 0; QLIST_INIT(&job->inflight_reqs); qemu_co_rwlock_init(&job->flush_rwlock); start = 0; end = DIV_ROUND_UP(job->common.len / BDRV_SECTOR_SIZE, BACKUP_SECTORS_PER_CLUSTER); job->bitmap = hbitmap_alloc(end, 0); bdrv_set_enable_write_cache(target, true); bdrv_set_on_error(target, on_target_error, on_target_error); bdrv_iostatus_enable(target); bdrv_add_before_write_notifier(bs, &before_write); if (job->sync_mode == MIRROR_SYNC_MODE_NONE) { while (!block_job_is_cancelled(&job->common)) { /* Yield until the job is cancelled. We just let our before_write * notify callback service CoW requests. */ job->common.busy = false; qemu_coroutine_yield(); job->common.busy = true; } } else { /* Both FULL and TOP SYNC_MODE's require copying.. */ for (; start < end; start++) { bool error_is_read; if (block_job_is_cancelled(&job->common)) { break; } /* we need to yield so that qemu_aio_flush() returns. * (without, VM does not reboot) */ if (job->common.speed) { uint64_t delay_ns = ratelimit_calculate_delay( &job->limit, job->sectors_read); job->sectors_read = 0; block_job_sleep_ns(&job->common, QEMU_CLOCK_REALTIME, delay_ns); } else { block_job_sleep_ns(&job->common, QEMU_CLOCK_REALTIME, 0); } if (block_job_is_cancelled(&job->common)) { break; } if (job->sync_mode == MIRROR_SYNC_MODE_TOP) { int i, n; int alloced = 0; /* Check to see if these blocks are already in the * backing file. */ for (i = 0; i < BACKUP_SECTORS_PER_CLUSTER;) { /* bdrv_is_allocated() only returns true/false based * on the first set of sectors it comes across that * are are all in the same state. * For that reason we must verify each sector in the * backup cluster length. We end up copying more than * needed but at some point that is always the case. */ alloced = bdrv_is_allocated(bs, start * BACKUP_SECTORS_PER_CLUSTER + i, BACKUP_SECTORS_PER_CLUSTER - i, &n); i += n; 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(bs, start * BACKUP_SECTORS_PER_CLUSTER, BACKUP_SECTORS_PER_CLUSTER, &error_is_read); 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(&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); hbitmap_free(job->bitmap); bdrv_iostatus_disable(target); data = g_malloc(sizeof(*data)); data->ret = ret; block_job_defer_to_main_loop(&job->common, backup_complete, data); } void backup_start(BlockDriverState *bs, BlockDriverState *target, int64_t speed, MirrorSyncMode sync_mode, BlockdevOnError on_source_error, BlockdevOnError on_target_error, BlockCompletionFunc *cb, void *opaque, Error **errp) { int64_t len; assert(bs); assert(target); assert(cb); if ((on_source_error == BLOCKDEV_ON_ERROR_STOP || on_source_error == BLOCKDEV_ON_ERROR_ENOSPC) && !bdrv_iostatus_is_enabled(bs)) { error_set(errp, QERR_INVALID_PARAMETER, "on-source-error"); return; } len = bdrv_getlength(bs); if (len < 0) { error_setg_errno(errp, -len, "unable to get length for '%s'", bdrv_get_device_name(bs)); return; } BackupBlockJob *job = block_job_create(&backup_job_driver, bs, speed, cb, opaque, errp); if (!job) { return; } job->on_source_error = on_source_error; job->on_target_error = on_target_error; job->target = target; job->sync_mode = sync_mode; job->common.len = len; job->common.co = qemu_coroutine_create(backup_run); qemu_coroutine_enter(job->common.co, job); }