Use the component callbacks; prepare, abort, and clean.
NB: prepare is only called when the job has not yet failed;
and abort can be called after prepare.
complete -> prepare -> abort -> clean
complete -> abort -> clean
During refactor, a potential problem with bdrv_drop_intermediate
was identified, The patched behavior is no worse than the pre-patch
behavior, so leave a FIXME for now to be fixed in a future patch.
Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
---
block/commit.c | 92 ++++++++++++++++++++++++++++++++--------------------------
1 file changed, 51 insertions(+), 41 deletions(-)
diff --git a/block/commit.c b/block/commit.c
index b6e8969877..a2da5740b0 100644
--- a/block/commit.c
+++ b/block/commit.c
@@ -36,6 +36,7 @@ typedef struct CommitBlockJob {
BlockDriverState *commit_top_bs;
BlockBackend *top;
BlockBackend *base;
+ BlockDriverState *base_bs;
BlockdevOnError on_error;
int base_flags;
char *backing_file_str;
@@ -68,61 +69,67 @@ static int coroutine_fn commit_populate(BlockBackend *bs, BlockBackend *base,
return 0;
}
-static void commit_exit(Job *job)
+static int commit_prepare(Job *job)
{
CommitBlockJob *s = container_of(job, CommitBlockJob, common.job);
- BlockJob *bjob = &s->common;
- BlockDriverState *top = blk_bs(s->top);
- BlockDriverState *base = blk_bs(s->base);
- BlockDriverState *commit_top_bs = s->commit_top_bs;
- bool remove_commit_top_bs = false;
-
- /* Make sure commit_top_bs and top stay around until bdrv_replace_node() */
- bdrv_ref(top);
- bdrv_ref(commit_top_bs);
/* Remove base node parent that still uses BLK_PERM_WRITE/RESIZE before
* the normal backing chain can be restored. */
blk_unref(s->base);
+ s->base = NULL;
- if (!job_is_cancelled(job) && job->ret == 0) {
- /* success */
- job->ret = bdrv_drop_intermediate(s->commit_top_bs, base,
- s->backing_file_str);
- } else {
- /* XXX Can (or should) we somehow keep 'consistent read' blocked even
- * after the failed/cancelled commit job is gone? If we already wrote
- * something to base, the intermediate images aren't valid any more. */
- remove_commit_top_bs = true;
+ /* FIXME: bdrv_drop_intermediate treats total failures and partial failures
+ * identically. Further work is needed to disambiguate these cases. */
+ return bdrv_drop_intermediate(s->commit_top_bs, s->base_bs,
+ s->backing_file_str);
+}
+
+static void commit_abort(Job *job)
+{
+ CommitBlockJob *s = container_of(job, CommitBlockJob, common.job);
+ BlockDriverState *top_bs = blk_bs(s->top);
+
+ /* Make sure commit_top_bs and top stay around until bdrv_replace_node() */
+ bdrv_ref(top_bs);
+ bdrv_ref(s->commit_top_bs);
+
+ if (s->base) {
+ blk_unref(s->base);
}
+ /* free the blockers on the intermediate nodes so that bdrv_replace_nodes
+ * can succeed */
+ block_job_remove_all_bdrv(&s->common);
+
+ /* If bdrv_drop_intermediate() failed (or was not invoked), remove the
+ * commit filter driver from the backing chain now. Do this as the final
+ * step so that the 'consistent read' permission can be granted.
+ *
+ * XXX Can (or should) we somehow keep 'consistent read' blocked even
+ * after the failed/cancelled commit job is gone? If we already wrote
+ * something to base, the intermediate images aren't valid any more. */
+ bdrv_child_try_set_perm(s->commit_top_bs->backing, 0, BLK_PERM_ALL,
+ &error_abort);
+ bdrv_replace_node(s->commit_top_bs, backing_bs(s->commit_top_bs),
+ &error_abort);
+
+ bdrv_unref(s->commit_top_bs);
+ bdrv_unref(top_bs);
+}
+
+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_flags != bdrv_get_flags(base)) {
- bdrv_reopen(base, s->base_flags, NULL);
+ if (s->base_flags != bdrv_get_flags(s->base_bs)) {
+ bdrv_reopen(s->base_bs, s->base_flags, NULL);
}
+
g_free(s->backing_file_str);
blk_unref(s->top);
-
- /* If there is more than one reference to the job (e.g. if called from
- * job_finish_sync()), job_completed() won't free it and therefore the
- * blockers on the intermediate nodes remain. This would cause
- * bdrv_set_backing_hd() to fail. */
- block_job_remove_all_bdrv(bjob);
-
- /* If bdrv_drop_intermediate() didn't already do that, remove the commit
- * filter driver from the backing chain. Do this as the final step so that
- * the 'consistent read' permission can be granted. */
- if (remove_commit_top_bs) {
- bdrv_child_try_set_perm(commit_top_bs->backing, 0, BLK_PERM_ALL,
- &error_abort);
- bdrv_replace_node(commit_top_bs, backing_bs(commit_top_bs),
- &error_abort);
- }
-
- bdrv_unref(commit_top_bs);
- bdrv_unref(top);
}
static int coroutine_fn commit_run(Job *job, Error **errp)
@@ -211,7 +218,9 @@ static const BlockJobDriver commit_job_driver = {
.user_resume = block_job_user_resume,
.drain = block_job_drain,
.run = commit_run,
- .exit = commit_exit,
+ .prepare = commit_prepare,
+ .abort = commit_abort,
+ .clean = commit_clean
},
};
@@ -345,6 +354,7 @@ void commit_start(const char *job_id, BlockDriverState *bs,
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);
--
2.14.4
On Thu, Sep 06, 2018 at 09:02:13AM -0400, John Snow wrote:
> Use the component callbacks; prepare, abort, and clean.
>
> NB: prepare is only called when the job has not yet failed;
> and abort can be called after prepare.
>
> complete -> prepare -> abort -> clean
> complete -> abort -> clean
>
> During refactor, a potential problem with bdrv_drop_intermediate
> was identified, The patched behavior is no worse than the pre-patch
> behavior, so leave a FIXME for now to be fixed in a future patch.
>
> Signed-off-by: John Snow <jsnow@redhat.com>
> Reviewed-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Jeff Cody <jcody@redhat.com>
> ---
> block/commit.c | 92 ++++++++++++++++++++++++++++++++--------------------------
> 1 file changed, 51 insertions(+), 41 deletions(-)
>
> diff --git a/block/commit.c b/block/commit.c
> index b6e8969877..a2da5740b0 100644
> --- a/block/commit.c
> +++ b/block/commit.c
> @@ -36,6 +36,7 @@ typedef struct CommitBlockJob {
> BlockDriverState *commit_top_bs;
> BlockBackend *top;
> BlockBackend *base;
> + BlockDriverState *base_bs;
> BlockdevOnError on_error;
> int base_flags;
> char *backing_file_str;
> @@ -68,61 +69,67 @@ static int coroutine_fn commit_populate(BlockBackend *bs, BlockBackend *base,
> return 0;
> }
>
> -static void commit_exit(Job *job)
> +static int commit_prepare(Job *job)
> {
> CommitBlockJob *s = container_of(job, CommitBlockJob, common.job);
> - BlockJob *bjob = &s->common;
> - BlockDriverState *top = blk_bs(s->top);
> - BlockDriverState *base = blk_bs(s->base);
> - BlockDriverState *commit_top_bs = s->commit_top_bs;
> - bool remove_commit_top_bs = false;
> -
> - /* Make sure commit_top_bs and top stay around until bdrv_replace_node() */
> - bdrv_ref(top);
> - bdrv_ref(commit_top_bs);
>
> /* Remove base node parent that still uses BLK_PERM_WRITE/RESIZE before
> * the normal backing chain can be restored. */
> blk_unref(s->base);
> + s->base = NULL;
>
> - if (!job_is_cancelled(job) && job->ret == 0) {
> - /* success */
> - job->ret = bdrv_drop_intermediate(s->commit_top_bs, base,
> - s->backing_file_str);
> - } else {
> - /* XXX Can (or should) we somehow keep 'consistent read' blocked even
> - * after the failed/cancelled commit job is gone? If we already wrote
> - * something to base, the intermediate images aren't valid any more. */
> - remove_commit_top_bs = true;
> + /* FIXME: bdrv_drop_intermediate treats total failures and partial failures
> + * identically. Further work is needed to disambiguate these cases. */
> + return bdrv_drop_intermediate(s->commit_top_bs, s->base_bs,
> + s->backing_file_str);
> +}
> +
> +static void commit_abort(Job *job)
> +{
> + CommitBlockJob *s = container_of(job, CommitBlockJob, common.job);
> + BlockDriverState *top_bs = blk_bs(s->top);
> +
> + /* Make sure commit_top_bs and top stay around until bdrv_replace_node() */
> + bdrv_ref(top_bs);
> + bdrv_ref(s->commit_top_bs);
> +
> + if (s->base) {
> + blk_unref(s->base);
> }
>
> + /* free the blockers on the intermediate nodes so that bdrv_replace_nodes
> + * can succeed */
> + block_job_remove_all_bdrv(&s->common);
> +
> + /* If bdrv_drop_intermediate() failed (or was not invoked), remove the
> + * commit filter driver from the backing chain now. Do this as the final
> + * step so that the 'consistent read' permission can be granted.
> + *
> + * XXX Can (or should) we somehow keep 'consistent read' blocked even
> + * after the failed/cancelled commit job is gone? If we already wrote
> + * something to base, the intermediate images aren't valid any more. */
> + bdrv_child_try_set_perm(s->commit_top_bs->backing, 0, BLK_PERM_ALL,
> + &error_abort);
> + bdrv_replace_node(s->commit_top_bs, backing_bs(s->commit_top_bs),
> + &error_abort);
> +
> + bdrv_unref(s->commit_top_bs);
> + bdrv_unref(top_bs);
> +}
> +
> +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_flags != bdrv_get_flags(base)) {
> - bdrv_reopen(base, s->base_flags, NULL);
> + if (s->base_flags != bdrv_get_flags(s->base_bs)) {
> + bdrv_reopen(s->base_bs, s->base_flags, NULL);
> }
> +
> g_free(s->backing_file_str);
> blk_unref(s->top);
> -
> - /* If there is more than one reference to the job (e.g. if called from
> - * job_finish_sync()), job_completed() won't free it and therefore the
> - * blockers on the intermediate nodes remain. This would cause
> - * bdrv_set_backing_hd() to fail. */
> - block_job_remove_all_bdrv(bjob);
> -
> - /* If bdrv_drop_intermediate() didn't already do that, remove the commit
> - * filter driver from the backing chain. Do this as the final step so that
> - * the 'consistent read' permission can be granted. */
> - if (remove_commit_top_bs) {
> - bdrv_child_try_set_perm(commit_top_bs->backing, 0, BLK_PERM_ALL,
> - &error_abort);
> - bdrv_replace_node(commit_top_bs, backing_bs(commit_top_bs),
> - &error_abort);
> - }
> -
> - bdrv_unref(commit_top_bs);
> - bdrv_unref(top);
> }
>
> static int coroutine_fn commit_run(Job *job, Error **errp)
> @@ -211,7 +218,9 @@ static const BlockJobDriver commit_job_driver = {
> .user_resume = block_job_user_resume,
> .drain = block_job_drain,
> .run = commit_run,
> - .exit = commit_exit,
> + .prepare = commit_prepare,
> + .abort = commit_abort,
> + .clean = commit_clean
> },
> };
>
> @@ -345,6 +354,7 @@ void commit_start(const char *job_id, BlockDriverState *bs,
> 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);
> --
> 2.14.4
>
On 2018-09-06 15:02, John Snow wrote: > Use the component callbacks; prepare, abort, and clean. > > NB: prepare is only called when the job has not yet failed; > and abort can be called after prepare. > > complete -> prepare -> abort -> clean > complete -> abort -> clean > > During refactor, a potential problem with bdrv_drop_intermediate > was identified, The patched behavior is no worse than the pre-patch (s/T/t/) (Max) > behavior, so leave a FIXME for now to be fixed in a future patch. > > Signed-off-by: John Snow <jsnow@redhat.com> > Reviewed-by: Max Reitz <mreitz@redhat.com> > --- > block/commit.c | 92 ++++++++++++++++++++++++++++++++-------------------------- > 1 file changed, 51 insertions(+), 41 deletions(-)
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