| Message ID | 20201016171057.6182-3-vsementsov@virtuozzo.com |
|---|---|
| State | Superseded |
| Headers | show |
| Series | block: deal with errp: part I | expand |
Am 16.10.2020 um 19:10 hat Vladimir Sementsov-Ogievskiy geschrieben: > Now bdrv_append returns status and we can drop all the local_err things > around it. > > Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> > Reviewed-by: Greg Kurz <groug@kaod.org> > Reviewed-by: Alberto Garcia <berto@igalia.com> > --- > block.c | 5 +---- > block/backup-top.c | 20 ++++++++------------ > block/commit.c | 5 +---- > block/mirror.c | 6 ++---- > blockdev.c | 4 +--- > tests/test-bdrv-graph-mod.c | 6 +++--- > 6 files changed, 16 insertions(+), 30 deletions(-) > > diff --git a/block.c b/block.c > index b05fbff42d..7b6818c681 100644 > --- a/block.c > +++ b/block.c > @@ -3161,7 +3161,6 @@ static BlockDriverState *bdrv_append_temp_snapshot(BlockDriverState *bs, > int64_t total_size; > QemuOpts *opts = NULL; > BlockDriverState *bs_snapshot = NULL; > - Error *local_err = NULL; > int ret; > > /* if snapshot, we create a temporary backing file and open it > @@ -3208,9 +3207,7 @@ static BlockDriverState *bdrv_append_temp_snapshot(BlockDriverState *bs, > * order to be able to return one, we have to increase > * bs_snapshot's refcount here */ > bdrv_ref(bs_snapshot); > - bdrv_append(bs_snapshot, bs, &local_err); > - if (local_err) { > - error_propagate(errp, local_err); > + if (bdrv_append(bs_snapshot, bs, errp) < 0) { We generally avoid calling functions with side effects inside a comparison. Let's use the usual pattern: ret = bdrv_append(bs_snapshot, bs, errp); if (ret < 0) { ... } (I mention it only once, but there are multiple instances in this patch.) > bs_snapshot = NULL; > goto out; > } > diff --git a/tests/test-bdrv-graph-mod.c b/tests/test-bdrv-graph-mod.c > index 8cff13830e..2b71601c24 100644 > --- a/tests/test-bdrv-graph-mod.c > +++ b/tests/test-bdrv-graph-mod.c > @@ -101,7 +101,7 @@ static BlockDriverState *pass_through_node(const char *name) > */ > static void test_update_perm_tree(void) > { > - Error *local_err = NULL; > + int ret; > > BlockBackend *root = blk_new(qemu_get_aio_context(), > BLK_PERM_WRITE | BLK_PERM_CONSISTENT_READ, > @@ -114,8 +114,8 @@ static void test_update_perm_tree(void) > bdrv_attach_child(filter, bs, "child", &child_of_bds, > BDRV_CHILD_FILTERED | BDRV_CHILD_PRIMARY, &error_abort); > > - bdrv_append(filter, bs, &local_err); > - error_free_or_abort(&local_err); > + ret = bdrv_append(filter, bs, NULL); > + assert(ret < 0); Usually, test cases use g_assert_cmpint() which prints the expected and actual value if it fails. Kevin
Kevin Wolf <kwolf@redhat.com> writes: > Am 16.10.2020 um 19:10 hat Vladimir Sementsov-Ogievskiy geschrieben: >> Now bdrv_append returns status and we can drop all the local_err things >> around it. >> >> Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> >> Reviewed-by: Greg Kurz <groug@kaod.org> >> Reviewed-by: Alberto Garcia <berto@igalia.com> >> --- >> block.c | 5 +---- >> block/backup-top.c | 20 ++++++++------------ >> block/commit.c | 5 +---- >> block/mirror.c | 6 ++---- >> blockdev.c | 4 +--- >> tests/test-bdrv-graph-mod.c | 6 +++--- >> 6 files changed, 16 insertions(+), 30 deletions(-) >> >> diff --git a/block.c b/block.c >> index b05fbff42d..7b6818c681 100644 >> --- a/block.c >> +++ b/block.c >> @@ -3161,7 +3161,6 @@ static BlockDriverState *bdrv_append_temp_snapshot(BlockDriverState *bs, >> int64_t total_size; >> QemuOpts *opts = NULL; >> BlockDriverState *bs_snapshot = NULL; >> - Error *local_err = NULL; >> int ret; >> >> /* if snapshot, we create a temporary backing file and open it >> @@ -3208,9 +3207,7 @@ static BlockDriverState *bdrv_append_temp_snapshot(BlockDriverState *bs, >> * order to be able to return one, we have to increase >> * bs_snapshot's refcount here */ >> bdrv_ref(bs_snapshot); >> - bdrv_append(bs_snapshot, bs, &local_err); >> - if (local_err) { >> - error_propagate(errp, local_err); >> + if (bdrv_append(bs_snapshot, bs, errp) < 0) { > > We generally avoid calling functions with side effects inside a > comparison. Let's use the usual pattern: > > ret = bdrv_append(bs_snapshot, bs, errp); > if (ret < 0) { > ... > } I'd also advice against buring side effects too deep, but calling a function in a failure-checking conditional is pretty benign. It's also common: $ git-grep 'if ([a-z].*) < 0) {' coughs up several hundred instances. That said, there is none in block.c. Local consistency matters. [...]
Am 19.10.2020 um 17:45 hat Markus Armbruster geschrieben: > Kevin Wolf <kwolf@redhat.com> writes: > > > Am 16.10.2020 um 19:10 hat Vladimir Sementsov-Ogievskiy geschrieben: > >> Now bdrv_append returns status and we can drop all the local_err things > >> around it. > >> > >> Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> > >> Reviewed-by: Greg Kurz <groug@kaod.org> > >> Reviewed-by: Alberto Garcia <berto@igalia.com> > >> --- > >> block.c | 5 +---- > >> block/backup-top.c | 20 ++++++++------------ > >> block/commit.c | 5 +---- > >> block/mirror.c | 6 ++---- > >> blockdev.c | 4 +--- > >> tests/test-bdrv-graph-mod.c | 6 +++--- > >> 6 files changed, 16 insertions(+), 30 deletions(-) > >> > >> diff --git a/block.c b/block.c > >> index b05fbff42d..7b6818c681 100644 > >> --- a/block.c > >> +++ b/block.c > >> @@ -3161,7 +3161,6 @@ static BlockDriverState *bdrv_append_temp_snapshot(BlockDriverState *bs, > >> int64_t total_size; > >> QemuOpts *opts = NULL; > >> BlockDriverState *bs_snapshot = NULL; > >> - Error *local_err = NULL; > >> int ret; > >> > >> /* if snapshot, we create a temporary backing file and open it > >> @@ -3208,9 +3207,7 @@ static BlockDriverState *bdrv_append_temp_snapshot(BlockDriverState *bs, > >> * order to be able to return one, we have to increase > >> * bs_snapshot's refcount here */ > >> bdrv_ref(bs_snapshot); > >> - bdrv_append(bs_snapshot, bs, &local_err); > >> - if (local_err) { > >> - error_propagate(errp, local_err); > >> + if (bdrv_append(bs_snapshot, bs, errp) < 0) { > > > > We generally avoid calling functions with side effects inside a > > comparison. Let's use the usual pattern: > > > > ret = bdrv_append(bs_snapshot, bs, errp); > > if (ret < 0) { > > ... > > } > > I'd also advice against buring side effects too deep, but calling a > function in a failure-checking conditional is pretty benign. It's also > common: > > $ git-grep 'if ([a-z].*) < 0) {' > > coughs up several hundred instances. > > That said, there is none in block.c. Local consistency matters. Actually, after looking at the rest of the series, I also need to be a bit more specific: We do have boolean if (!foo()), it's just the negative errno ones that aren't very common in the block layer. And the reason why it's not very common is probably that 0/-errno is very common in the block layer and a check for < 0 just throws the specific errno away. We had a lot of such code, which was wrong because it lost information instead of passing the real error to the caller. I guess this is the real origin of the block layer habits to avoid it. Kevin
diff --git a/block.c b/block.c index b05fbff42d..7b6818c681 100644 --- a/block.c +++ b/block.c @@ -3161,7 +3161,6 @@ static BlockDriverState *bdrv_append_temp_snapshot(BlockDriverState *bs, int64_t total_size; QemuOpts *opts = NULL; BlockDriverState *bs_snapshot = NULL; - Error *local_err = NULL; int ret; /* if snapshot, we create a temporary backing file and open it @@ -3208,9 +3207,7 @@ static BlockDriverState *bdrv_append_temp_snapshot(BlockDriverState *bs, * order to be able to return one, we have to increase * bs_snapshot's refcount here */ bdrv_ref(bs_snapshot); - bdrv_append(bs_snapshot, bs, &local_err); - if (local_err) { - error_propagate(errp, local_err); + if (bdrv_append(bs_snapshot, bs, errp) < 0) { bs_snapshot = NULL; goto out; } diff --git a/block/backup-top.c b/block/backup-top.c index fe6883cc97..eb6a34b726 100644 --- a/block/backup-top.c +++ b/block/backup-top.c @@ -190,7 +190,7 @@ BlockDriverState *bdrv_backup_top_append(BlockDriverState *source, BlockCopyState **bcs, Error **errp) { - Error *local_err = NULL; + ERRP_GUARD(); BDRVBackupTopState *state; BlockDriverState *top; bool appended = false; @@ -223,9 +223,8 @@ BlockDriverState *bdrv_backup_top_append(BlockDriverState *source, bdrv_drained_begin(source); bdrv_ref(top); - bdrv_append(top, source, &local_err); - if (local_err) { - error_prepend(&local_err, "Cannot append backup-top filter: "); + if (bdrv_append(top, source, errp) < 0) { + error_prepend(errp, "Cannot append backup-top filter: "); goto fail; } appended = true; @@ -235,18 +234,16 @@ BlockDriverState *bdrv_backup_top_append(BlockDriverState *source, * we want. */ state->active = true; - bdrv_child_refresh_perms(top, top->backing, &local_err); - if (local_err) { - error_prepend(&local_err, - "Cannot set permissions for backup-top filter: "); + if (bdrv_child_refresh_perms(top, top->backing, errp) < 0) { + error_prepend(errp, "Cannot set permissions for backup-top filter: "); goto fail; } state->cluster_size = cluster_size; state->bcs = block_copy_state_new(top->backing, state->target, - cluster_size, write_flags, &local_err); - if (local_err) { - error_prepend(&local_err, "Cannot create block-copy-state: "); + cluster_size, write_flags, errp); + if (!state->bcs) { + error_prepend(errp, "Cannot create block-copy-state: "); goto fail; } *bcs = state->bcs; @@ -264,7 +261,6 @@ fail: } bdrv_drained_end(source); - error_propagate(errp, local_err); return NULL; } diff --git a/block/commit.c b/block/commit.c index 1e85c306cc..6da0902f9d 100644 --- a/block/commit.c +++ b/block/commit.c @@ -254,7 +254,6 @@ void commit_start(const char *job_id, BlockDriverState *bs, BlockDriverState *iter; BlockDriverState *commit_top_bs = NULL; BlockDriverState *filtered_base; - Error *local_err = NULL; int64_t base_size, top_size; uint64_t base_perms, iter_shared_perms; int ret; @@ -312,10 +311,8 @@ void commit_start(const char *job_id, BlockDriverState *bs, commit_top_bs->total_sectors = top->total_sectors; - bdrv_append(commit_top_bs, top, &local_err); - if (local_err) { + if (bdrv_append(commit_top_bs, top, errp) < 0) { commit_top_bs = NULL; - error_propagate(errp, local_err); goto fail; } diff --git a/block/mirror.c b/block/mirror.c index 26acf4af6f..b3778248b8 100644 --- a/block/mirror.c +++ b/block/mirror.c @@ -1560,7 +1560,6 @@ static BlockJob *mirror_start_job( BlockDriverState *mirror_top_bs; bool target_is_backing; uint64_t target_perms, target_shared_perms; - Error *local_err = NULL; int ret; if (granularity == 0) { @@ -1609,12 +1608,11 @@ static BlockJob *mirror_start_job( * it alive until block_job_create() succeeds even if bs has no parent. */ bdrv_ref(mirror_top_bs); bdrv_drained_begin(bs); - bdrv_append(mirror_top_bs, bs, &local_err); + ret = bdrv_append(mirror_top_bs, bs, errp); bdrv_drained_end(bs); - if (local_err) { + if (ret < 0) { bdrv_unref(mirror_top_bs); - error_propagate(errp, local_err); return NULL; } diff --git a/blockdev.c b/blockdev.c index fe6fb5dc1d..3a896181fd 100644 --- a/blockdev.c +++ b/blockdev.c @@ -1591,9 +1591,7 @@ static void external_snapshot_prepare(BlkActionState *common, * can fail, so we need to do it in .prepare; undoing it for abort is * always possible. */ bdrv_ref(state->new_bs); - bdrv_append(state->new_bs, state->old_bs, &local_err); - if (local_err) { - error_propagate(errp, local_err); + if (bdrv_append(state->new_bs, state->old_bs, errp) < 0) { goto out; } state->overlay_appended = true; diff --git a/tests/test-bdrv-graph-mod.c b/tests/test-bdrv-graph-mod.c index 8cff13830e..2b71601c24 100644 --- a/tests/test-bdrv-graph-mod.c +++ b/tests/test-bdrv-graph-mod.c @@ -101,7 +101,7 @@ static BlockDriverState *pass_through_node(const char *name) */ static void test_update_perm_tree(void) { - Error *local_err = NULL; + int ret; BlockBackend *root = blk_new(qemu_get_aio_context(), BLK_PERM_WRITE | BLK_PERM_CONSISTENT_READ, @@ -114,8 +114,8 @@ static void test_update_perm_tree(void) bdrv_attach_child(filter, bs, "child", &child_of_bds, BDRV_CHILD_FILTERED | BDRV_CHILD_PRIMARY, &error_abort); - bdrv_append(filter, bs, &local_err); - error_free_or_abort(&local_err); + ret = bdrv_append(filter, bs, NULL); + assert(ret < 0); blk_unref(root); }