--- /dev/null
+/*
+ * Image streaming
+ *
+ * Copyright IBM, Corp. 2011
+ *
+ * Authors:
+ * Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
+ *
+ * This work is licensed under the terms of the GNU LGPL, version 2 or later.
+ * See the COPYING.LIB file in the top-level directory.
+ *
+ */
+
+#include "trace.h"
+#include "block/block_int.h"
+#include "block/blockjob.h"
+#include "qapi/qmp/qerror.h"
+#include "qemu/ratelimit.h"
+
+enum {
+ /*
+ * Size of data buffer for populating the image file. This should be large
+ * enough to process multiple clusters in a single call, so that populating
+ * contiguous regions of the image is efficient.
+ */
+ STREAM_BUFFER_SIZE = 512 * 1024, /* in bytes */
+};
+
+#define SLICE_TIME 100000000ULL /* ns */
+
+typedef struct StreamBlockJob {
+ BlockJob common;
+ RateLimit limit;
+ BlockDriverState *base;
+ BlockdevOnError on_error;
+ char *backing_file_str;
+} StreamBlockJob;
+
+static int coroutine_fn stream_populate(BlockDriverState *bs,
+ int64_t sector_num, int nb_sectors,
+ void *buf)
+{
+ struct iovec iov = {
+ .iov_base = buf,
+ .iov_len = nb_sectors * BDRV_SECTOR_SIZE,
+ };
+ QEMUIOVector qiov;
+
+ qemu_iovec_init_external(&qiov, &iov, 1);
+
+ /* Copy-on-read the unallocated clusters */
+ return bdrv_co_copy_on_readv(bs, sector_num, nb_sectors, &qiov);
+}
+
+static void close_unused_images(BlockDriverState *top, BlockDriverState *base,
+ const char *base_id)
+{
+ BlockDriverState *intermediate;
+ intermediate = top->backing_hd;
+
+ /* Must assign before bdrv_delete() to prevent traversing dangling pointer
+ * while we delete backing image instances.
+ */
+ bdrv_set_backing_hd(top, base);
+
+ while (intermediate) {
+ BlockDriverState *unused;
+
+ /* reached base */
+ if (intermediate == base) {
+ break;
+ }
+
+ unused = intermediate;
+ intermediate = intermediate->backing_hd;
+ bdrv_set_backing_hd(unused, NULL);
+ bdrv_unref(unused);
+ }
+
+ bdrv_refresh_limits(top, NULL);
+}
+
+typedef struct {
+ int ret;
+ bool reached_end;
+} StreamCompleteData;
+
+static void stream_complete(BlockJob *job, void *opaque)
+{
+ StreamBlockJob *s = container_of(job, StreamBlockJob, common);
+ StreamCompleteData *data = opaque;
+ BlockDriverState *base = s->base;
+
+ if (!block_job_is_cancelled(&s->common) && data->reached_end &&
+ data->ret == 0) {
+ const char *base_id = NULL, *base_fmt = NULL;
+ if (base) {
+ base_id = s->backing_file_str;
+ if (base->drv) {
+ base_fmt = base->drv->format_name;
+ }
+ }
+ data->ret = bdrv_change_backing_file(job->bs, base_id, base_fmt);
+ close_unused_images(job->bs, base, base_id);
+ }
+
+ g_free(s->backing_file_str);
+ block_job_completed(&s->common, data->ret);
+ g_free(data);
+}
+
+static void coroutine_fn stream_run(void *opaque)
+{
+ StreamBlockJob *s = opaque;
+ StreamCompleteData *data;
+ BlockDriverState *bs = s->common.bs;
+ BlockDriverState *base = s->base;
+ int64_t sector_num, end;
+ int error = 0;
+ int ret = 0;
+ int n = 0;
+ void *buf;
+
+ if (!bs->backing_hd) {
+ block_job_completed(&s->common, 0);
+ return;
+ }
+
+ s->common.len = bdrv_getlength(bs);
+ if (s->common.len < 0) {
+ block_job_completed(&s->common, s->common.len);
+ return;
+ }
+
+ end = s->common.len >> BDRV_SECTOR_BITS;
+ buf = qemu_blockalign(bs, STREAM_BUFFER_SIZE);
+
+ /* Turn on copy-on-read for the whole block device so that guest read
+ * requests help us make progress. Only do this when copying the entire
+ * backing chain since the copy-on-read operation does not take base into
+ * account.
+ */
+ if (!base) {
+ bdrv_enable_copy_on_read(bs);
+ }
+
+ for (sector_num = 0; sector_num < end; sector_num += n) {
+ uint64_t delay_ns = 0;
+ bool copy;
+
+wait:
+ /* Note that even when no rate limit is applied we need to yield
+ * with no pending I/O here so that bdrv_drain_all() returns.
+ */
+ block_job_sleep_ns(&s->common, QEMU_CLOCK_REALTIME, delay_ns);
+ if (block_job_is_cancelled(&s->common)) {
+ break;
+ }
+
+ copy = false;
+
+ ret = bdrv_is_allocated(bs, sector_num,
+ STREAM_BUFFER_SIZE / BDRV_SECTOR_SIZE, &n);
+ if (ret == 1) {
+ /* Allocated in the top, no need to copy. */
+ } else if (ret >= 0) {
+ /* Copy if allocated in the intermediate images. Limit to the
+ * known-unallocated area [sector_num, sector_num+n). */
+ ret = bdrv_is_allocated_above(bs->backing_hd, base,
+ sector_num, n, &n);
+
+ /* Finish early if end of backing file has been reached */
+ if (ret == 0 && n == 0) {
+ n = end - sector_num;
+ }
+
+ copy = (ret == 1);
+ }
+ trace_stream_one_iteration(s, sector_num, n, ret);
+ if (copy) {
+ if (s->common.speed) {
+ delay_ns = ratelimit_calculate_delay(&s->limit, n);
+ if (delay_ns > 0) {
+ goto wait;
+ }
+ }
+ ret = stream_populate(bs, sector_num, n, buf);
+ }
+ if (ret < 0) {
+ BlockErrorAction action =
+ block_job_error_action(&s->common, s->common.bs, s->on_error,
+ true, -ret);
+ if (action == BLOCK_ERROR_ACTION_STOP) {
+ n = 0;
+ continue;
+ }
+ if (error == 0) {
+ error = ret;
+ }
+ if (action == BLOCK_ERROR_ACTION_REPORT) {
+ break;
+ }
+ }
+ ret = 0;
+
+ /* Publish progress */
+ s->common.offset += n * BDRV_SECTOR_SIZE;
+ }
+
+ if (!base) {
+ bdrv_disable_copy_on_read(bs);
+ }
+
+ /* Do not remove the backing file if an error was there but ignored. */
+ ret = error;
+
+ qemu_vfree(buf);
+
+ /* Modify backing chain and close BDSes in main loop */
+ data = g_malloc(sizeof(*data));
+ data->ret = ret;
+ data->reached_end = sector_num == end;
+ block_job_defer_to_main_loop(&s->common, stream_complete, data);
+}
+
+static void stream_set_speed(BlockJob *job, int64_t speed, Error **errp)
+{
+ StreamBlockJob *s = container_of(job, StreamBlockJob, common);
+
+ if (speed < 0) {
+ error_setg(errp, QERR_INVALID_PARAMETER, "speed");
+ return;
+ }
+ ratelimit_set_speed(&s->limit, speed / BDRV_SECTOR_SIZE, SLICE_TIME);
+}
+
+static const BlockJobDriver stream_job_driver = {
+ .instance_size = sizeof(StreamBlockJob),
+ .job_type = BLOCK_JOB_TYPE_STREAM,
+ .set_speed = stream_set_speed,
+};
+
+void stream_start(BlockDriverState *bs, BlockDriverState *base,
+ const char *backing_file_str, int64_t speed,
+ BlockdevOnError on_error,
+ BlockCompletionFunc *cb,
+ void *opaque, Error **errp)
+{
+ StreamBlockJob *s;
+
+ if ((on_error == BLOCKDEV_ON_ERROR_STOP ||
+ on_error == BLOCKDEV_ON_ERROR_ENOSPC) &&
+ !bdrv_iostatus_is_enabled(bs)) {
+ error_setg(errp, QERR_INVALID_PARAMETER, "on-error");
+ return;
+ }
+
+ s = block_job_create(&stream_job_driver, bs, speed, cb, opaque, errp);
+ if (!s) {
+ return;
+ }
+
+ s->base = base;
+ s->backing_file_str = g_strdup(backing_file_str);
+
+ s->on_error = on_error;
+ s->common.co = qemu_coroutine_create(stream_run);
+ trace_stream_start(bs, base, s, s->common.co, opaque);
+ qemu_coroutine_enter(s->common.co, s);
+}
Code Review / kvmfornfv.git / blobdiff