Initial import of abandoned HQEMU version 2.5.2HEADmaster

1 files changed, 586 insertions, 0 deletions

diff --git a/src/block/backup.c b/src/block/backup.c
new file mode 100644
index 0000000..705bb77
--- /dev/null
+++ b/src/block/backup.c
@@ -0,0 +1,586 @@
+/*
+ * 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"
+#include "sysemu/block-backend.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,
+                                      bool is_write_notifier)
+{
+    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);
+
+        if (is_write_notifier) {
+            ret = bdrv_co_readv_no_serialising(bs,
+                                           start * BACKUP_SECTORS_PER_CLUSTER,
+                                           n, &bounce_qiov);
+        } else {
+            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, true);
+}
+
+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);
+
+    if (s->target->blk) {
+        blk_iostatus_reset(s->target->blk);
+    }
+}
+
+static void backup_cleanup_sync_bitmap(BackupBlockJob *job, int ret)
+{
+    BdrvDirtyBitmap *bm;
+    BlockDriverState *bs = job->common.bs;
+
+    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);
+    }
+}
+
+static void backup_commit(BlockJob *job)
+{
+    BackupBlockJob *s = container_of(job, BackupBlockJob, common);
+    if (s->sync_bitmap) {
+        backup_cleanup_sync_bitmap(s, 0);
+    }
+}
+
+static void backup_abort(BlockJob *job)
+{
+    BackupBlockJob *s = container_of(job, BackupBlockJob, common);
+    if (s->sync_bitmap) {
+        backup_cleanup_sync_bitmap(s, -1);
+    }
+}
+
+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,
+    .commit         = backup_commit,
+    .abort          = backup_abort,
+};
+
+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,
+                                    false);
+                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);
+    if (target->blk) {
+        blk_set_on_error(target->blk, on_target_error, on_target_error);
+        blk_iostatus_enable(target->blk);
+    }
+
+    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, 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(&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);
+
+    if (target->blk) {
+        blk_iostatus_disable(target->blk);
+    }
+    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,
+                  BlockJobTxn *txn, 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) &&
+        (!bs->blk || !blk_iostatus_is_enabled(bs->blk))) {
+        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);
+    block_job_txn_add_job(txn, &job->common);
+    qemu_coroutine_enter(job->common.co, job);
+    return;
+
+ error:
+    if (sync_bitmap) {
+        bdrv_reclaim_dirty_bitmap(bs, sync_bitmap, NULL);
+    }
+}