--- /dev/null
+/*
+ * 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 "qapi/qmp/qerror.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;
+ /* bitmap for sync=incremental */
+ BdrvDirtyBitmap *sync_bitmap;
+ 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_setg(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 bool coroutine_fn yield_and_check(BackupBlockJob *job)
+{
+ if (block_job_is_cancelled(&job->common)) {
+ return true;
+ }
+
+ /* we need to yield so that bdrv_drain_all() 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)) {
+ return true;
+ }
+
+ return false;
+}
+
+static int coroutine_fn backup_run_incremental(BackupBlockJob *job)
+{
+ bool error_is_read;
+ int ret = 0;
+ int clusters_per_iter;
+ uint32_t granularity;
+ int64_t sector;
+ int64_t cluster;
+ int64_t end;
+ int64_t last_cluster = -1;
+ BlockDriverState *bs = job->common.bs;
+ HBitmapIter hbi;
+
+ granularity = bdrv_dirty_bitmap_granularity(job->sync_bitmap);
+ clusters_per_iter = MAX((granularity / BACKUP_CLUSTER_SIZE), 1);
+ bdrv_dirty_iter_init(job->sync_bitmap, &hbi);
+
+ /* Find the next dirty sector(s) */
+ while ((sector = hbitmap_iter_next(&hbi)) != -1) {
+ cluster = sector / BACKUP_SECTORS_PER_CLUSTER;
+
+ /* Fake progress updates for any clusters we skipped */
+ if (cluster != last_cluster + 1) {
+ job->common.offset += ((cluster - last_cluster - 1) *
+ BACKUP_CLUSTER_SIZE);
+ }
+
+ for (end = cluster + clusters_per_iter; cluster < end; cluster++) {
+ do {
+ if (yield_and_check(job)) {
+ return ret;
+ }
+ ret = backup_do_cow(bs, cluster * BACKUP_SECTORS_PER_CLUSTER,
+ BACKUP_SECTORS_PER_CLUSTER, &error_is_read);
+ if ((ret < 0) &&
+ backup_error_action(job, error_is_read, -ret) ==
+ BLOCK_ERROR_ACTION_REPORT) {
+ return ret;
+ }
+ } while (ret < 0);
+ }
+
+ /* If the bitmap granularity is smaller than the backup granularity,
+ * we need to advance the iterator pointer to the next cluster. */
+ if (granularity < BACKUP_CLUSTER_SIZE) {
+ bdrv_set_dirty_iter(&hbi, cluster * BACKUP_SECTORS_PER_CLUSTER);
+ }
+
+ last_cluster = cluster - 1;
+ }
+
+ /* Play some final catchup with the progress meter */
+ end = DIV_ROUND_UP(job->common.len, BACKUP_CLUSTER_SIZE);
+ if (last_cluster + 1 < end) {
+ job->common.offset += ((end - last_cluster - 1) * BACKUP_CLUSTER_SIZE);
+ }
+
+ return ret;
+}
+
+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, BACKUP_CLUSTER_SIZE);
+
+ 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 if (job->sync_mode == MIRROR_SYNC_MODE_INCREMENTAL) {
+ ret = backup_run_incremental(job);
+ } else {
+ /* Both FULL and TOP SYNC_MODE's require copying.. */
+ for (; start < end; start++) {
+ bool error_is_read;
+ if (yield_and_check(job)) {
+ 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);
+
+ if (job->sync_bitmap) {
+ BdrvDirtyBitmap *bm;
+ if (ret < 0 || block_job_is_cancelled(&job->common)) {
+ /* Merge the successor back into the parent, delete nothing. */
+ bm = bdrv_reclaim_dirty_bitmap(bs, job->sync_bitmap, NULL);
+ assert(bm);
+ } else {
+ /* Everything is fine, delete this bitmap and install the backup. */
+ bm = bdrv_dirty_bitmap_abdicate(bs, job->sync_bitmap, NULL);
+ assert(bm);
+ }
+ }
+ hbitmap_free(job->bitmap);
+
+ bdrv_iostatus_disable(target);
+ bdrv_op_unblock_all(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(BlockDriverState *bs, BlockDriverState *target,
+ int64_t speed, MirrorSyncMode sync_mode,
+ BdrvDirtyBitmap *sync_bitmap,
+ BlockdevOnError on_source_error,
+ BlockdevOnError on_target_error,
+ BlockCompletionFunc *cb, void *opaque,
+ Error **errp)
+{
+ int64_t len;
+
+ assert(bs);
+ assert(target);
+ assert(cb);
+
+ if (bs == target) {
+ error_setg(errp, "Source and target cannot be the same");
+ return;
+ }
+
+ if ((on_source_error == BLOCKDEV_ON_ERROR_STOP ||
+ on_source_error == BLOCKDEV_ON_ERROR_ENOSPC) &&
+ !bdrv_iostatus_is_enabled(bs)) {
+ error_setg(errp, QERR_INVALID_PARAMETER, "on-source-error");
+ 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 (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;
+ }
+
+ BackupBlockJob *job = block_job_create(&backup_job_driver, bs, speed,
+ cb, opaque, errp);
+ if (!job) {
+ goto error;
+ }
+
+ bdrv_op_block_all(target, job->common.blocker);
+
+ job->on_source_error = on_source_error;
+ job->on_target_error = on_target_error;
+ job->target = target;
+ job->sync_mode = sync_mode;
+ job->sync_bitmap = sync_mode == MIRROR_SYNC_MODE_INCREMENTAL ?
+ sync_bitmap : NULL;
+ job->common.len = len;
+ job->common.co = qemu_coroutine_create(backup_run);
+ qemu_coroutine_enter(job->common.co, job);
+ return;
+
+ error:
+ if (sync_bitmap) {
+ bdrv_reclaim_dirty_bitmap(bs, sync_bitmap, NULL);
+ }
+}
Code Review / kvmfornfv.git / blobdiff