static void commit_clean(Job *job)
{
CommitBlockJob *s = container_of(job, CommitBlockJob, common.job);
/* 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_read_only) {
bdrv_reopen_set_read_only(s->base_bs, true, NULL);
}
g_free(s->backing_file_str);
blk_unref(s->top);
}
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_read_only) {
/* Give up write permissions before making it read-only */
blk_set_perm(bjob->blk, 0, BLK_PERM_ALL, &error_abort);
bdrv_reopen_set_read_only(bs, true, NULL);
}
g_free(s->backing_file_str);
}
void stream_start(const char *job_id, BlockDriverState *bs,
BlockDriverState *base, const char *backing_file_str,
int creation_flags, int64_t speed,
BlockdevOnError on_error, Error **errp)
{
StreamBlockJob *s;
BlockDriverState *iter;
bool bs_read_only;
if (bdrv_freeze_backing_chain(bs, base, errp) < 0) {
return;
}
/* Make sure that the image is opened in read-write mode */
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;
}
}
/* Prevent concurrent jobs trying to modify the graph structure here, we
* 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, 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)) {
block_job_add_bdrv(&s->common, "intermediate node", iter, 0,
BLK_PERM_CONSISTENT_READ | BLK_PERM_WRITE_UNCHANGED,
&error_abort);
}
s->base = base;
s->backing_file_str = g_strdup(backing_file_str);
s->bs_read_only = bs_read_only;
s->chain_frozen = true;
s->on_error = on_error;
trace_stream_start(bs, base, s);
job_start(&s->common.job);
return;
fail:
if (bs_read_only) {
bdrv_reopen_set_read_only(bs, true, NULL);
}
bdrv_unfreeze_backing_chain(bs, base);
}
/* commit COW file into the raw image */
int bdrv_commit(BlockDriverState *bs)
{
BlockBackend *src, *backing;
BlockDriverState *backing_file_bs = NULL;
BlockDriverState *commit_top_bs = NULL;
BlockDriver *drv = bs->drv;
int64_t offset, length, backing_length;
int ro;
int64_t n;
int ret = 0;
uint8_t *buf = NULL;
Error *local_err = NULL;
if (!drv)
return -ENOMEDIUM;
if (!bs->backing) {
return -ENOTSUP;
}
if (bdrv_op_is_blocked(bs, BLOCK_OP_TYPE_COMMIT_SOURCE, NULL) ||
bdrv_op_is_blocked(bs->backing->bs, BLOCK_OP_TYPE_COMMIT_TARGET, NULL)) {
return -EBUSY;
}
ro = bs->backing->bs->read_only;
if (ro) {
if (bdrv_reopen_set_read_only(bs->backing->bs, false, NULL)) {
return -EACCES;
}
}
src = blk_new(BLK_PERM_CONSISTENT_READ, BLK_PERM_ALL);
backing = blk_new(BLK_PERM_WRITE | BLK_PERM_RESIZE, BLK_PERM_ALL);
ret = blk_insert_bs(src, bs, &local_err);
if (ret < 0) {
error_report_err(local_err);
goto ro_cleanup;
}
/* Insert commit_top block node above backing, so we can write to it */
backing_file_bs = backing_bs(bs);
commit_top_bs = bdrv_new_open_driver(&bdrv_commit_top, NULL, BDRV_O_RDWR,
&local_err);
if (commit_top_bs == NULL) {
error_report_err(local_err);
goto ro_cleanup;
}
bdrv_set_aio_context(commit_top_bs, bdrv_get_aio_context(backing_file_bs));
bdrv_set_backing_hd(commit_top_bs, backing_file_bs, &error_abort);
bdrv_set_backing_hd(bs, commit_top_bs, &error_abort);
ret = blk_insert_bs(backing, backing_file_bs, &local_err);
if (ret < 0) {
error_report_err(local_err);
goto ro_cleanup;
}
length = blk_getlength(src);
if (length < 0) {
ret = length;
goto ro_cleanup;
}
backing_length = blk_getlength(backing);
if (backing_length < 0) {
ret = backing_length;
goto ro_cleanup;
}
/* If our top snapshot is larger than the backing file image,
* grow the backing file image if possible. If not possible,
* we must return an error */
if (length > backing_length) {
ret = blk_truncate(backing, length, PREALLOC_MODE_OFF, &local_err);
if (ret < 0) {
error_report_err(local_err);
goto ro_cleanup;
}
}
/* blk_try_blockalign() for src will choose an alignment that works for
* backing as well, so no need to compare the alignment manually. */
buf = blk_try_blockalign(src, COMMIT_BUF_SIZE);
if (buf == NULL) {
ret = -ENOMEM;
goto ro_cleanup;
}
for (offset = 0; offset < length; offset += n) {
ret = bdrv_is_allocated(bs, offset, COMMIT_BUF_SIZE, &n);
if (ret < 0) {
goto ro_cleanup;
}
if (ret) {
ret = blk_pread(src, offset, buf, n);
if (ret < 0) {
goto ro_cleanup;
}
ret = blk_pwrite(backing, offset, buf, n, 0);
if (ret < 0) {
goto ro_cleanup;
}
}
}
if (drv->bdrv_make_empty) {
ret = drv->bdrv_make_empty(bs);
if (ret < 0) {
goto ro_cleanup;
}
blk_flush(src);
}
/*
* Make sure all data we wrote to the backing device is actually
* stable on disk.
*/
blk_flush(backing);
ret = 0;
ro_cleanup:
qemu_vfree(buf);
blk_unref(backing);
if (backing_file_bs) {
bdrv_set_backing_hd(bs, backing_file_bs, &error_abort);
}
bdrv_unref(commit_top_bs);
blk_unref(src);
if (ro) {
/* ignoring error return here */
bdrv_reopen_set_read_only(bs->backing->bs, true, NULL);
}
return ret;
}
void commit_start(const char *job_id, BlockDriverState *bs,
BlockDriverState *base, BlockDriverState *top,
int creation_flags, int64_t speed,
BlockdevOnError on_error, const char *backing_file_str,
const char *filter_node_name, Error **errp)
{
CommitBlockJob *s;
BlockDriverState *iter;
BlockDriverState *commit_top_bs = NULL;
Error *local_err = NULL;
int ret;
assert(top != bs);
if (top == base) {
error_setg(errp, "Invalid files for merge: top and base are the same");
return;
}
s = block_job_create(job_id, &commit_job_driver, NULL, bs, 0, BLK_PERM_ALL,
speed, creation_flags, NULL, NULL, errp);
if (!s) {
return;
}
/* convert base to r/w, if necessary */
s->base_read_only = bdrv_is_read_only(base);
if (s->base_read_only) {
if (bdrv_reopen_set_read_only(base, false, errp) != 0) {
goto fail;
}
}
/* Insert commit_top block node above top, so we can block consistent read
* on the backing chain below it */
commit_top_bs = bdrv_new_open_driver(&bdrv_commit_top, filter_node_name, 0,
errp);
if (commit_top_bs == NULL) {
goto fail;
}
if (!filter_node_name) {
commit_top_bs->implicit = true;
}
commit_top_bs->total_sectors = top->total_sectors;
bdrv_set_aio_context(commit_top_bs, bdrv_get_aio_context(top));
bdrv_set_backing_hd(commit_top_bs, top, &local_err);
if (local_err) {
bdrv_unref(commit_top_bs);
commit_top_bs = NULL;
error_propagate(errp, local_err);
goto fail;
}
bdrv_replace_node(top, commit_top_bs, &local_err);
if (local_err) {
bdrv_unref(commit_top_bs);
commit_top_bs = NULL;
error_propagate(errp, local_err);
goto fail;
}
s->commit_top_bs = commit_top_bs;
bdrv_unref(commit_top_bs);
/* Block all nodes between top and base, because they will
* disappear from the chain after this operation. */
assert(bdrv_chain_contains(top, base));
for (iter = top; iter != base; iter = backing_bs(iter)) {
/* XXX BLK_PERM_WRITE needs to be allowed so we don't block ourselves
* at s->base (if writes are blocked for a node, they are also blocked
* for its backing file). The other options would be a second filter
* driver above s->base. */
ret = block_job_add_bdrv(&s->common, "intermediate node", iter, 0,
BLK_PERM_WRITE_UNCHANGED | BLK_PERM_WRITE,
errp);
if (ret < 0) {
goto fail;
}
}
if (bdrv_freeze_backing_chain(commit_top_bs, base, errp) < 0) {
goto fail;
}
s->chain_frozen = true;
ret = block_job_add_bdrv(&s->common, "base", base, 0, BLK_PERM_ALL, errp);
if (ret < 0) {
goto fail;
}
s->base = blk_new(BLK_PERM_CONSISTENT_READ
| BLK_PERM_WRITE
| BLK_PERM_RESIZE,
BLK_PERM_CONSISTENT_READ
| BLK_PERM_GRAPH_MOD
| BLK_PERM_WRITE_UNCHANGED);
ret = blk_insert_bs(s->base, base, errp);
if (ret < 0) {
goto fail;
}
s->base_bs = base;
/* Required permissions are already taken with block_job_add_bdrv() */
s->top = blk_new(0, BLK_PERM_ALL);
ret = blk_insert_bs(s->top, top, errp);
if (ret < 0) {
goto fail;
}
s->backing_file_str = g_strdup(backing_file_str);
s->on_error = on_error;
trace_commit_start(bs, base, top, s);
job_start(&s->common.job);
return;
fail:
if (s->chain_frozen) {
bdrv_unfreeze_backing_chain(commit_top_bs, base);
}
if (s->base) {
blk_unref(s->base);
}
if (s->top) {
blk_unref(s->top);
}
job_early_fail(&s->common.job);
/* commit_top_bs has to be replaced after deleting the block job,
* otherwise this would fail because of lack of permissions. */
if (commit_top_bs) {
bdrv_replace_node(commit_top_bs, top, &error_abort);
}
}