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.
+ * Maximum chunk size to feed to copy-on-read. 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 */
+ STREAM_CHUNK = 512 * 1024, /* in bytes */
};
typedef struct StreamBlockJob {
BlockJob common;
- BlockDriverState *base;
+ BlockDriverState *base_overlay; /* COW overlay (stream from this) */
+ BlockDriverState *above_base; /* Node directly above the base */
BlockdevOnError on_error;
char *backing_file_str;
- int bs_flags;
+ bool bs_read_only;
+ bool chain_frozen;
} StreamBlockJob;
static int coroutine_fn stream_populate(BlockBackend *blk,
- int64_t offset, uint64_t bytes,
- void *buf)
+ int64_t offset, uint64_t bytes)
{
- struct iovec iov = {
- .iov_base = buf,
- .iov_len = bytes,
- };
- QEMUIOVector qiov;
-
assert(bytes < SIZE_MAX);
- qemu_iovec_init_external(&qiov, &iov, 1);
- /* Copy-on-read the unallocated clusters */
- return blk_co_preadv(blk, offset, qiov.size, &qiov, BDRV_REQ_COPY_ON_READ);
+ return blk_co_preadv(blk, offset, bytes, NULL,
+ BDRV_REQ_COPY_ON_READ | BDRV_REQ_PREFETCH);
+}
+
+static void stream_abort(Job *job)
+{
+ StreamBlockJob *s = container_of(job, StreamBlockJob, common.job);
+
+ if (s->chain_frozen) {
+ BlockJob *bjob = &s->common;
+ bdrv_unfreeze_backing_chain(blk_bs(bjob->blk), s->above_base);
+ }
}
-static void stream_exit(Job *job)
+static int stream_prepare(Job *job)
{
StreamBlockJob *s = container_of(job, StreamBlockJob, common.job);
BlockJob *bjob = &s->common;
BlockDriverState *bs = blk_bs(bjob->blk);
- BlockDriverState *base = s->base;
+ BlockDriverState *unfiltered_bs = bdrv_skip_filters(bs);
+ BlockDriverState *base = bdrv_filter_or_cow_bs(s->above_base);
Error *local_err = NULL;
- int ret = job->ret;
+ int ret = 0;
- if (!job_is_cancelled(job) && bs->backing && ret == 0) {
+ bdrv_unfreeze_backing_chain(bs, s->above_base);
+ s->chain_frozen = false;
+
+ if (bdrv_cow_child(unfiltered_bs)) {
const char *base_id = NULL, *base_fmt = NULL;
if (base) {
base_id = s->backing_file_str;
base_fmt = base->drv->format_name;
}
}
- ret = bdrv_change_backing_file(bs, base_id, base_fmt);
- bdrv_set_backing_hd(bs, base, &local_err);
+ bdrv_set_backing_hd(unfiltered_bs, base, &local_err);
+ ret = bdrv_change_backing_file(unfiltered_bs, base_id, base_fmt, false);
if (local_err) {
error_report_err(local_err);
- ret = -EPERM;
- goto out;
+ return -EPERM;
}
}
-out:
+ return ret;
+}
+
+static void stream_clean(Job *job)
+{
+ StreamBlockJob *s = container_of(job, StreamBlockJob, common.job);
+ BlockJob *bjob = &s->common;
+ BlockDriverState *bs = blk_bs(bjob->blk);
+
/* Reopen the image back in read-only mode if necessary */
- if (s->bs_flags != bdrv_get_flags(bs)) {
+ if (s->bs_read_only) {
/* Give up write permissions before making it read-only */
blk_set_perm(bjob->blk, 0, BLK_PERM_ALL, &error_abort);
- bdrv_reopen(bs, s->bs_flags, NULL);
+ bdrv_reopen_set_read_only(bs, true, NULL);
}
g_free(s->backing_file_str);
- job->ret = ret;
}
static int coroutine_fn stream_run(Job *job, Error **errp)
StreamBlockJob *s = container_of(job, StreamBlockJob, common.job);
BlockBackend *blk = s->common.blk;
BlockDriverState *bs = blk_bs(blk);
- BlockDriverState *base = s->base;
+ BlockDriverState *unfiltered_bs = bdrv_skip_filters(bs);
+ bool enable_cor = !bdrv_cow_child(s->base_overlay);
int64_t len;
int64_t offset = 0;
uint64_t delay_ns = 0;
int error = 0;
- int ret = 0;
int64_t n = 0; /* bytes */
- void *buf;
- if (!bs->backing) {
- goto out;
+ if (unfiltered_bs == s->base_overlay) {
+ /* Nothing to stream */
+ return 0;
}
len = bdrv_getlength(bs);
if (len < 0) {
- ret = len;
- goto out;
+ return len;
}
job_progress_set_remaining(&s->common.job, len);
- 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) {
+ if (enable_cor) {
bdrv_enable_copy_on_read(bs);
}
for ( ; offset < len; offset += n) {
bool copy;
+ int ret;
/* 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.
copy = false;
- ret = bdrv_is_allocated(bs, offset, STREAM_BUFFER_SIZE, &n);
+ ret = bdrv_is_allocated(unfiltered_bs, offset, STREAM_CHUNK, &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 [offset, offset+n*BDRV_SECTOR_SIZE). */
- ret = bdrv_is_allocated_above(backing_bs(bs), base,
+ ret = bdrv_is_allocated_above(bdrv_cow_bs(unfiltered_bs),
+ s->base_overlay, true,
offset, n, &n);
-
/* Finish early if end of backing file has been reached */
if (ret == 0 && n == 0) {
n = len - offset;
}
trace_stream_one_iteration(s, offset, n, ret);
if (copy) {
- ret = stream_populate(blk, offset, n, buf);
+ ret = stream_populate(blk, offset, n);
}
if (ret < 0) {
BlockErrorAction action =
break;
}
}
- ret = 0;
/* Publish progress */
job_progress_update(&s->common.job, n);
}
}
- if (!base) {
+ if (enable_cor) {
bdrv_disable_copy_on_read(bs);
}
- /* Do not remove the backing file if an error was there but ignored. */
- ret = error;
-
- qemu_vfree(buf);
-
-out:
- /* Modify backing chain and close BDSes in main loop */
- return ret;
+ /* Do not remove the backing file if an error was there but ignored. */
+ return error;
}
static const BlockJobDriver stream_job_driver = {
.job_type = JOB_TYPE_STREAM,
.free = block_job_free,
.run = stream_run,
- .exit = stream_exit,
+ .prepare = stream_prepare,
+ .abort = stream_abort,
+ .clean = stream_clean,
.user_resume = block_job_user_resume,
- .drain = block_job_drain,
},
};
void stream_start(const char *job_id, BlockDriverState *bs,
BlockDriverState *base, const char *backing_file_str,
- int64_t speed, BlockdevOnError on_error, Error **errp)
+ int creation_flags, int64_t speed,
+ BlockdevOnError on_error, Error **errp)
{
StreamBlockJob *s;
BlockDriverState *iter;
- int orig_bs_flags;
+ bool bs_read_only;
+ int basic_flags = BLK_PERM_CONSISTENT_READ | BLK_PERM_WRITE_UNCHANGED;
+ BlockDriverState *base_overlay = bdrv_find_overlay(bs, base);
+ BlockDriverState *above_base;
+
+ if (!base_overlay) {
+ error_setg(errp, "'%s' is not in the backing chain of '%s'",
+ base->node_name, bs->node_name);
+ return;
+ }
+
+ /*
+ * Find the node directly above @base. @base_overlay is a COW overlay, so
+ * it must have a bdrv_cow_child(), but it is the immediate overlay of
+ * @base, so between the two there can only be filters.
+ */
+ above_base = base_overlay;
+ if (bdrv_cow_bs(above_base) != base) {
+ above_base = bdrv_cow_bs(above_base);
+ while (bdrv_filter_bs(above_base) != base) {
+ above_base = bdrv_filter_bs(above_base);
+ }
+ }
+
+ if (bdrv_freeze_backing_chain(bs, above_base, errp) < 0) {
+ return;
+ }
/* Make sure that the image is opened in read-write mode */
- orig_bs_flags = bdrv_get_flags(bs);
- if (!(orig_bs_flags & BDRV_O_RDWR)) {
- if (bdrv_reopen(bs, orig_bs_flags | BDRV_O_RDWR, errp) != 0) {
- return;
+ bs_read_only = bdrv_is_read_only(bs);
+ if (bs_read_only) {
+ if (bdrv_reopen_set_read_only(bs, false, errp) != 0) {
+ bs_read_only = false;
+ goto fail;
}
}
* already have our own plans. Also don't allow resize as the image size is
* queried only at the job start and then cached. */
s = block_job_create(job_id, &stream_job_driver, NULL, bs,
- BLK_PERM_CONSISTENT_READ | BLK_PERM_WRITE_UNCHANGED |
- BLK_PERM_GRAPH_MOD,
- BLK_PERM_CONSISTENT_READ | BLK_PERM_WRITE_UNCHANGED |
- BLK_PERM_WRITE,
- speed, JOB_DEFAULT, NULL, NULL, errp);
+ basic_flags | BLK_PERM_GRAPH_MOD,
+ basic_flags | BLK_PERM_WRITE,
+ speed, creation_flags, NULL, NULL, errp);
if (!s) {
goto fail;
}
/* Block all intermediate nodes between bs and base, because they will
* disappear from the chain after this operation. The streaming job reads
- * every block only once, assuming that it doesn't change, so block writes
- * and resizes. */
- for (iter = backing_bs(bs); iter && iter != base; iter = backing_bs(iter)) {
+ * every block only once, assuming that it doesn't change, so forbid writes
+ * and resizes. Reassign the base node pointer because the backing BS of the
+ * bottom node might change after the call to bdrv_reopen_set_read_only()
+ * due to parallel block jobs running.
+ * above_base node might change after the call to
+ * bdrv_reopen_set_read_only() due to parallel block jobs running.
+ */
+ base = bdrv_filter_or_cow_bs(above_base);
+ for (iter = bdrv_filter_or_cow_bs(bs); iter != base;
+ iter = bdrv_filter_or_cow_bs(iter))
+ {
block_job_add_bdrv(&s->common, "intermediate node", iter, 0,
- BLK_PERM_CONSISTENT_READ | BLK_PERM_WRITE_UNCHANGED,
- &error_abort);
+ basic_flags, &error_abort);
}
- s->base = base;
+ s->base_overlay = base_overlay;
+ s->above_base = above_base;
s->backing_file_str = g_strdup(backing_file_str);
- s->bs_flags = orig_bs_flags;
+ s->bs_read_only = bs_read_only;
+ s->chain_frozen = true;
s->on_error = on_error;
trace_stream_start(bs, base, s);
return;
fail:
- if (orig_bs_flags != bdrv_get_flags(bs)) {
- bdrv_reopen(bs, orig_bs_flags, NULL);
+ if (bs_read_only) {
+ bdrv_reopen_set_read_only(bs, true, NULL);
}
+ bdrv_unfreeze_backing_chain(bs, above_base);
}
projects / mirror_qemu.git / blobdiff