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-rw-r--r--block/backup.c105
1 files changed, 75 insertions, 30 deletions
diff --git a/block/backup.c b/block/backup.c
index 16105d40b1..6ae8a05a3e 100644
--- a/block/backup.c
+++ b/block/backup.c
@@ -37,6 +37,7 @@ typedef struct CowRequest {
typedef struct BackupBlockJob {
BlockJob common;
BlockDriverState *target;
+ MirrorSyncMode sync_mode;
RateLimit limit;
BlockdevOnError on_source_error;
BlockdevOnError on_target_error;
@@ -247,40 +248,83 @@ static void coroutine_fn backup_run(void *opaque)
bdrv_add_before_write_notifier(bs, &before_write);
- for (; start < end; start++) {
- bool error_is_read;
-
- if (block_job_is_cancelled(&job->common)) {
- break;
+ 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;
- /* 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, rt_clock, delay_ns);
- } else {
- block_job_sleep_ns(&job->common, rt_clock, 0);
- }
+ if (block_job_is_cancelled(&job->common)) {
+ break;
+ }
- 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, rt_clock, delay_ns);
+ } else {
+ block_job_sleep_ns(&job->common, rt_clock, 0);
+ }
- 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) {
+ if (block_job_is_cancelled(&job->common)) {
break;
- } else {
- start--;
- continue;
+ }
+
+ 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_co_is_allocated() only returns true/false based
+ * on the first set of sectors it comes accross 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_co_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;
+ }
}
}
}
@@ -300,7 +344,7 @@ static void coroutine_fn backup_run(void *opaque)
}
void backup_start(BlockDriverState *bs, BlockDriverState *target,
- int64_t speed,
+ int64_t speed, MirrorSyncMode sync_mode,
BlockdevOnError on_source_error,
BlockdevOnError on_target_error,
BlockDriverCompletionFunc *cb, void *opaque,
@@ -335,6 +379,7 @@ void backup_start(BlockDriverState *bs, BlockDriverState *target,
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);