--- /dev/null
+/*
+ * Live block commit
+ *
+ * Copyright Red Hat, Inc. 2012
+ *
+ * Authors:
+ * Based on stream.c by Stefan Hajnoczi
+ *
+ * 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_int.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.
+ */
+ COMMIT_BUFFER_SIZE = 512 * 1024, /* in bytes */
+};
+
+#define SLICE_TIME 100000000ULL /* ns */
+
+typedef struct CommitBlockJob {
+ BlockJob common;
+ RateLimit limit;
+ BlockDriverState *active;
+ BlockDriverState *top;
+ BlockDriverState *base;
+ BlockErrorAction on_error;
+ int base_flags;
+ int orig_overlay_flags;
+} CommitBlockJob;
+
+static int coroutine_fn commit_populate(BlockDriverState *bs,
+ BlockDriverState *base,
+ int64_t sector_num, int nb_sectors,
+ void *buf)
+{
+ int ret = 0;
+
+ ret = bdrv_read(bs, sector_num, buf, nb_sectors);
+ if (ret) {
+ return ret;
+ }
+
+ ret = bdrv_write(base, sector_num, buf, nb_sectors);
+ if (ret) {
+ return ret;
+ }
+
+ return 0;
+}
+
+static void coroutine_fn commit_run(void *opaque)
+{
+ CommitBlockJob *s = opaque;
+ BlockDriverState *active = s->active;
+ BlockDriverState *top = s->top;
+ BlockDriverState *base = s->base;
+ BlockDriverState *overlay_bs = NULL;
+ int64_t sector_num, end;
+ int ret = 0;
+ int n = 0;
+ void *buf;
+ int bytes_written = 0;
+ int64_t base_len;
+
+ ret = s->common.len = bdrv_getlength(top);
+
+
+ if (s->common.len < 0) {
+ goto exit_restore_reopen;
+ }
+
+ ret = base_len = bdrv_getlength(base);
+ if (base_len < 0) {
+ goto exit_restore_reopen;
+ }
+
+ if (base_len < s->common.len) {
+ ret = bdrv_truncate(base, s->common.len);
+ if (ret) {
+ goto exit_restore_reopen;
+ }
+ }
+
+ overlay_bs = bdrv_find_overlay(active, top);
+
+ end = s->common.len >> BDRV_SECTOR_BITS;
+ buf = qemu_blockalign(top, COMMIT_BUFFER_SIZE);
+
+ 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 qemu_aio_flush() returns.
+ */
+ block_job_sleep_ns(&s->common, rt_clock, delay_ns);
+ if (block_job_is_cancelled(&s->common)) {
+ break;
+ }
+ /* Copy if allocated above the base */
+ ret = bdrv_co_is_allocated_above(top, base, sector_num,
+ COMMIT_BUFFER_SIZE / BDRV_SECTOR_SIZE,
+ &n);
+ copy = (ret == 1);
+ trace_commit_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 = commit_populate(top, base, sector_num, n, buf);
+ bytes_written += n * BDRV_SECTOR_SIZE;
+ }
+ if (ret < 0) {
+ if (s->on_error == BLOCK_ERR_STOP_ANY ||
+ s->on_error == BLOCK_ERR_REPORT ||
+ (s->on_error == BLOCK_ERR_STOP_ENOSPC && ret == -ENOSPC)) {
+ goto exit_free_buf;
+ } else {
+ n = 0;
+ continue;
+ }
+ }
+ /* Publish progress */
+ s->common.offset += n * BDRV_SECTOR_SIZE;
+ }
+
+ ret = 0;
+
+ if (!block_job_is_cancelled(&s->common) && sector_num == end) {
+ /* success */
+ ret = bdrv_drop_intermediate(active, top, base);
+ }
+
+exit_free_buf:
+ qemu_vfree(buf);
+
+exit_restore_reopen:
+ /* restore base open flags here if appropriate (e.g., change the base back
+ * to r/o). These reopens do not need to be atomic, since we won't abort
+ * even on failure here */
+ if (s->base_flags != bdrv_get_flags(base)) {
+ bdrv_reopen(base, s->base_flags, NULL);
+ }
+ if (s->orig_overlay_flags != bdrv_get_flags(overlay_bs)) {
+ bdrv_reopen(overlay_bs, s->orig_overlay_flags, NULL);
+ }
+
+ block_job_complete(&s->common, ret);
+}
+
+static void commit_set_speed(BlockJob *job, int64_t speed, Error **errp)
+{
+ CommitBlockJob *s = container_of(job, CommitBlockJob, common);
+
+ if (speed < 0) {
+ error_set(errp, QERR_INVALID_PARAMETER, "speed");
+ return;
+ }
+ ratelimit_set_speed(&s->limit, speed / BDRV_SECTOR_SIZE, SLICE_TIME);
+}
+
+static BlockJobType commit_job_type = {
+ .instance_size = sizeof(CommitBlockJob),
+ .job_type = "commit",
+ .set_speed = commit_set_speed,
+};
+
+void commit_start(BlockDriverState *bs, BlockDriverState *base,
+ BlockDriverState *top, int64_t speed,
+ BlockErrorAction on_error, BlockDriverCompletionFunc *cb,
+ void *opaque, Error **errp)
+{
+ CommitBlockJob *s;
+ BlockReopenQueue *reopen_queue = NULL;
+ int orig_overlay_flags;
+ int orig_base_flags;
+ BlockDriverState *overlay_bs;
+ Error *local_err = NULL;
+
+ if ((on_error == BLOCK_ERR_STOP_ANY ||
+ on_error == BLOCK_ERR_STOP_ENOSPC) &&
+ !bdrv_iostatus_is_enabled(bs)) {
+ error_set(errp, QERR_INVALID_PARAMETER_COMBINATION);
+ return;
+ }
+
+ /* Once we support top == active layer, remove this check */
+ if (top == bs) {
+ error_setg(errp,
+ "Top image as the active layer is currently unsupported");
+ return;
+ }
+
+ if (top == base) {
+ error_setg(errp, "Invalid files for merge: top and base are the same");
+ return;
+ }
+
+ /* top and base may be valid, but let's make sure that base is reachable
+ * from top */
+ if (bdrv_find_backing_image(top, base->filename) != base) {
+ error_setg(errp,
+ "Base (%s) is not reachable from top (%s)",
+ base->filename, top->filename);
+ return;
+ }
+
+ overlay_bs = bdrv_find_overlay(bs, top);
+
+ if (overlay_bs == NULL) {
+ error_setg(errp, "Could not find overlay image for %s:", top->filename);
+ return;
+ }
+
+ orig_base_flags = bdrv_get_flags(base);
+ orig_overlay_flags = bdrv_get_flags(overlay_bs);
+
+ /* convert base & overlay_bs to r/w, if necessary */
+ if (!(orig_base_flags & BDRV_O_RDWR)) {
+ reopen_queue = bdrv_reopen_queue(reopen_queue, base,
+ orig_base_flags | BDRV_O_RDWR);
+ }
+ if (!(orig_overlay_flags & BDRV_O_RDWR)) {
+ reopen_queue = bdrv_reopen_queue(reopen_queue, overlay_bs,
+ orig_overlay_flags | BDRV_O_RDWR);
+ }
+ if (reopen_queue) {
+ bdrv_reopen_multiple(reopen_queue, &local_err);
+ if (local_err != NULL) {
+ error_propagate(errp, local_err);
+ return;
+ }
+ }
+
+
+ s = block_job_create(&commit_job_type, bs, speed, cb, opaque, errp);
+ if (!s) {
+ return;
+ }
+
+ s->base = base;
+ s->top = top;
+ s->active = bs;
+
+ s->base_flags = orig_base_flags;
+ s->orig_overlay_flags = orig_overlay_flags;
+
+ s->on_error = on_error;
+ s->common.co = qemu_coroutine_create(commit_run);
+
+ trace_commit_start(bs, base, top, s, s->common.co, opaque);
+ qemu_coroutine_enter(s->common.co, s);
+}
projects / qemu.git / commitdiff