| /* |
| * 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); |
| } 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; |
| |
| return backup_do_cow(req->bs, req->sector_num, req->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 BlockJobType backup_job_type = { |
| .instance_size = sizeof(BackupBlockJob), |
| .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); |
| } |
| } |
| |
| static void coroutine_fn backup_run(void *opaque) |
| { |
| BackupBlockJob *job = opaque; |
| 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) { |
| 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 == BDRV_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); |
| bdrv_unref(target); |
| |
| block_job_completed(&job->common, ret); |
| } |
| |
| void backup_start(BlockDriverState *bs, BlockDriverState *target, |
| int64_t speed, MirrorSyncMode sync_mode, |
| BlockdevOnError on_source_error, |
| BlockdevOnError on_target_error, |
| BlockDriverCompletionFunc *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_type, 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); |
| } |
