| Message ID | 20210317143529.615584-23-vsementsov@virtuozzo.com |
|---|---|
| State | New |
| Headers | show |
| Series | block: update graph permissions update | expand |
Am 17.03.2021 um 15:35 hat Vladimir Sementsov-Ogievskiy geschrieben: > Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> > --- > block.c | 78 +++++++++++++++++++++++++++++++++++++++++++++++++++++++-- > 1 file changed, 76 insertions(+), 2 deletions(-) > > diff --git a/block.c b/block.c > index 11f7ad0818..2fca1f2ad5 100644 > --- a/block.c > +++ b/block.c > @@ -2929,12 +2929,19 @@ static void bdrv_replace_child(BdrvChild *child, BlockDriverState *new_bs) > } > } > > +static void bdrv_child_free(void *opaque) > +{ > + BdrvChild *c = opaque; > + > + g_free(c->name); > + g_free(c); > +} > + > static void bdrv_remove_empty_child(BdrvChild *child) > { > assert(!child->bs); > QLIST_SAFE_REMOVE(child, next); > - g_free(child->name); > - g_free(child); > + bdrv_child_free(child); > } > > typedef struct BdrvAttachChildCommonState { > @@ -4956,6 +4963,73 @@ static bool should_update_child(BdrvChild *c, BlockDriverState *to) > return ret; > } > > +typedef struct BdrvRemoveFilterOrCowChild { > + BdrvChild *child; > + bool is_backing; > +} BdrvRemoveFilterOrCowChild; > + > +/* this doesn't restore original child bs, only the child itself */ Hm, this comment tells me that it's intentional, but why is it correct? > +static void bdrv_remove_filter_or_cow_child_abort(void *opaque) > +{ > + BdrvRemoveFilterOrCowChild *s = opaque; > + BlockDriverState *parent_bs = s->child->opaque; > + > + QLIST_INSERT_HEAD(&parent_bs->children, s->child, next); > + if (s->is_backing) { > + parent_bs->backing = s->child; > + } else { > + parent_bs->file = s->child; > + } > +} Kevin
26.04.2021 19:26, Kevin Wolf wrote: > Am 17.03.2021 um 15:35 hat Vladimir Sementsov-Ogievskiy geschrieben: >> Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> >> --- >> block.c | 78 +++++++++++++++++++++++++++++++++++++++++++++++++++++++-- >> 1 file changed, 76 insertions(+), 2 deletions(-) >> >> diff --git a/block.c b/block.c >> index 11f7ad0818..2fca1f2ad5 100644 >> --- a/block.c >> +++ b/block.c >> @@ -2929,12 +2929,19 @@ static void bdrv_replace_child(BdrvChild *child, BlockDriverState *new_bs) >> } >> } >> >> +static void bdrv_child_free(void *opaque) >> +{ >> + BdrvChild *c = opaque; >> + >> + g_free(c->name); >> + g_free(c); >> +} >> + >> static void bdrv_remove_empty_child(BdrvChild *child) >> { >> assert(!child->bs); >> QLIST_SAFE_REMOVE(child, next); >> - g_free(child->name); >> - g_free(child); >> + bdrv_child_free(child); >> } >> >> typedef struct BdrvAttachChildCommonState { >> @@ -4956,6 +4963,73 @@ static bool should_update_child(BdrvChild *c, BlockDriverState *to) >> return ret; >> } >> >> +typedef struct BdrvRemoveFilterOrCowChild { >> + BdrvChild *child; >> + bool is_backing; >> +} BdrvRemoveFilterOrCowChild; >> + >> +/* this doesn't restore original child bs, only the child itself */ > > Hm, this comment tells me that it's intentional, but why is it correct? that's because bdrv_remove_filter_or_cow_child_abort() aborts only part of bdrv_remove_filter_or_cow_child(). Look: bdrv_remove_filter_or_cow_child() firstly do bdrv_replace_child_safe(child, NULL, tran);, so bs would be restored by .abort() of bdrv_replace_child_safe() action. So, improved comment may look like: This doesn't restore original child bs, only the child itself. The bs would be restored by .abort() bdrv_replace_child_safe() subation of bdrv_remove_filter_or_cow_child() action. Probably it would be more correct to rename BdrvRemoveFilterOrCowChild -> BdrvRemoveFilterOrCowChildNoBs bdrv_remove_filter_or_cow_child_abort -> bdrv_remove_filter_or_cow_child_no_bs_abort bdrv_remove_filter_or_cow_child_commit -> bdrv_remove_filter_or_cow_child_no_bs_commit and assert on .abort() and .commit() that s->child->bs is NULL. > >> +static void bdrv_remove_filter_or_cow_child_abort(void *opaque) >> +{ >> + BdrvRemoveFilterOrCowChild *s = opaque; >> + BlockDriverState *parent_bs = s->child->opaque; >> + >> + QLIST_INSERT_HEAD(&parent_bs->children, s->child, next); >> + if (s->is_backing) { >> + parent_bs->backing = s->child; >> + } else { >> + parent_bs->file = s->child; >> + } >> +} > > Kevin >
Am 26.04.2021 um 19:18 hat Vladimir Sementsov-Ogievskiy geschrieben: > 26.04.2021 19:26, Kevin Wolf wrote: > > Am 17.03.2021 um 15:35 hat Vladimir Sementsov-Ogievskiy geschrieben: > > > Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> > > > --- > > > block.c | 78 +++++++++++++++++++++++++++++++++++++++++++++++++++++++-- > > > 1 file changed, 76 insertions(+), 2 deletions(-) > > > > > > diff --git a/block.c b/block.c > > > index 11f7ad0818..2fca1f2ad5 100644 > > > --- a/block.c > > > +++ b/block.c > > > @@ -2929,12 +2929,19 @@ static void bdrv_replace_child(BdrvChild *child, BlockDriverState *new_bs) > > > } > > > } > > > +static void bdrv_child_free(void *opaque) > > > +{ > > > + BdrvChild *c = opaque; > > > + > > > + g_free(c->name); > > > + g_free(c); > > > +} > > > + > > > static void bdrv_remove_empty_child(BdrvChild *child) > > > { > > > assert(!child->bs); > > > QLIST_SAFE_REMOVE(child, next); > > > - g_free(child->name); > > > - g_free(child); > > > + bdrv_child_free(child); > > > } > > > typedef struct BdrvAttachChildCommonState { > > > @@ -4956,6 +4963,73 @@ static bool should_update_child(BdrvChild *c, BlockDriverState *to) > > > return ret; > > > } > > > +typedef struct BdrvRemoveFilterOrCowChild { > > > + BdrvChild *child; > > > + bool is_backing; > > > +} BdrvRemoveFilterOrCowChild; > > > + > > > +/* this doesn't restore original child bs, only the child itself */ > > > > Hm, this comment tells me that it's intentional, but why is it correct? > > that's because bdrv_remove_filter_or_cow_child_abort() aborts only > part of bdrv_remove_filter_or_cow_child(). I see that it aborts only part of it, but why? Normally, a function getting a Transaction object suggests to me that on failure, all changes the function made will be reverted, not just parts of the changes. > Look: bdrv_remove_filter_or_cow_child() firstly do > bdrv_replace_child_safe(child, NULL, tran);, so bs would be restored > by .abort() of bdrv_replace_child_safe() action. Ah! So the reason is not that we don't want to restore child->bs, but that bdrv_replace_child_safe() is already transactionable and will automatically do this. > So, improved comment may look like: > > This doesn't restore original child bs, only the child itself. The bs > would be restored by .abort() bdrv_replace_child_safe() subation of > bdrv_remove_filter_or_cow_child() action. "subation" is a typo for "subaction"? Maybe something like this: We don't have to restore child->bs here to undo bdrv_replace_child() because that function is already transactionable and will do so in its own .abort() callback. > Probably it would be more correct to rename > > BdrvRemoveFilterOrCowChild -> BdrvRemoveFilterOrCowChildNoBs > bdrv_remove_filter_or_cow_child_abort -> bdrv_remove_filter_or_cow_child_no_bs_abort > bdrv_remove_filter_or_cow_child_commit -> bdrv_remove_filter_or_cow_child_no_bs_commit > > and assert on .abort() and .commit() that s->child->bs is NULL. I wouldn't bother with that. It was just that the comment confused me because it seemed to suggest that we actually don't want to restore child->bs, when its real intention was to say that it's already restored somewhere else. Kevin
27.04.2021 14:09, Kevin Wolf wrote: > Am 26.04.2021 um 19:18 hat Vladimir Sementsov-Ogievskiy geschrieben: >> 26.04.2021 19:26, Kevin Wolf wrote: >>> Am 17.03.2021 um 15:35 hat Vladimir Sementsov-Ogievskiy geschrieben: >>>> Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> >>>> --- >>>> block.c | 78 +++++++++++++++++++++++++++++++++++++++++++++++++++++++-- >>>> 1 file changed, 76 insertions(+), 2 deletions(-) >>>> >>>> diff --git a/block.c b/block.c >>>> index 11f7ad0818..2fca1f2ad5 100644 >>>> --- a/block.c >>>> +++ b/block.c >>>> @@ -2929,12 +2929,19 @@ static void bdrv_replace_child(BdrvChild *child, BlockDriverState *new_bs) >>>> } >>>> } >>>> +static void bdrv_child_free(void *opaque) >>>> +{ >>>> + BdrvChild *c = opaque; >>>> + >>>> + g_free(c->name); >>>> + g_free(c); >>>> +} >>>> + >>>> static void bdrv_remove_empty_child(BdrvChild *child) >>>> { >>>> assert(!child->bs); >>>> QLIST_SAFE_REMOVE(child, next); >>>> - g_free(child->name); >>>> - g_free(child); >>>> + bdrv_child_free(child); >>>> } >>>> typedef struct BdrvAttachChildCommonState { >>>> @@ -4956,6 +4963,73 @@ static bool should_update_child(BdrvChild *c, BlockDriverState *to) >>>> return ret; >>>> } >>>> +typedef struct BdrvRemoveFilterOrCowChild { >>>> + BdrvChild *child; >>>> + bool is_backing; >>>> +} BdrvRemoveFilterOrCowChild; >>>> + >>>> +/* this doesn't restore original child bs, only the child itself */ >>> >>> Hm, this comment tells me that it's intentional, but why is it correct? >> >> that's because bdrv_remove_filter_or_cow_child_abort() aborts only >> part of bdrv_remove_filter_or_cow_child(). > > I see that it aborts only part of it, but why? > > Normally, a function getting a Transaction object suggests to me that on > failure, all changes the function made will be reverted, not just parts > of the changes. > >> Look: bdrv_remove_filter_or_cow_child() firstly do >> bdrv_replace_child_safe(child, NULL, tran);, so bs would be restored >> by .abort() of bdrv_replace_child_safe() action. > > Ah! So the reason is not that we don't want to restore child->bs, but > that bdrv_replace_child_safe() is already transactionable and will > automatically do this. > >> So, improved comment may look like: >> >> This doesn't restore original child bs, only the child itself. The bs >> would be restored by .abort() bdrv_replace_child_safe() subation of >> bdrv_remove_filter_or_cow_child() action. > > "subation" is a typo for "subaction"? > > Maybe something like this: > > We don't have to restore child->bs here to undo bdrv_replace_child() > because that function is already transactionable and will do so in > its own .abort() callback. Sounds good, thanks > >> Probably it would be more correct to rename >> >> BdrvRemoveFilterOrCowChild -> BdrvRemoveFilterOrCowChildNoBs >> bdrv_remove_filter_or_cow_child_abort -> bdrv_remove_filter_or_cow_child_no_bs_abort >> bdrv_remove_filter_or_cow_child_commit -> bdrv_remove_filter_or_cow_child_no_bs_commit >> >> and assert on .abort() and .commit() that s->child->bs is NULL. > > I wouldn't bother with that. It was just that the comment confused me > because it seemed to suggest that we actually don't want to restore > child->bs, when its real intention was to say that it's already restored > somewhere else. > OK
diff --git a/block.c b/block.c index 11f7ad0818..2fca1f2ad5 100644 --- a/block.c +++ b/block.c @@ -2929,12 +2929,19 @@ static void bdrv_replace_child(BdrvChild *child, BlockDriverState *new_bs) } } +static void bdrv_child_free(void *opaque) +{ + BdrvChild *c = opaque; + + g_free(c->name); + g_free(c); +} + static void bdrv_remove_empty_child(BdrvChild *child) { assert(!child->bs); QLIST_SAFE_REMOVE(child, next); - g_free(child->name); - g_free(child); + bdrv_child_free(child); } typedef struct BdrvAttachChildCommonState { @@ -4956,6 +4963,73 @@ static bool should_update_child(BdrvChild *c, BlockDriverState *to) return ret; } +typedef struct BdrvRemoveFilterOrCowChild { + BdrvChild *child; + bool is_backing; +} BdrvRemoveFilterOrCowChild; + +/* this doesn't restore original child bs, only the child itself */ +static void bdrv_remove_filter_or_cow_child_abort(void *opaque) +{ + BdrvRemoveFilterOrCowChild *s = opaque; + BlockDriverState *parent_bs = s->child->opaque; + + QLIST_INSERT_HEAD(&parent_bs->children, s->child, next); + if (s->is_backing) { + parent_bs->backing = s->child; + } else { + parent_bs->file = s->child; + } +} + +static void bdrv_remove_filter_or_cow_child_commit(void *opaque) +{ + BdrvRemoveFilterOrCowChild *s = opaque; + + bdrv_child_free(s->child); +} + +static TransactionActionDrv bdrv_remove_filter_or_cow_child_drv = { + .abort = bdrv_remove_filter_or_cow_child_abort, + .commit = bdrv_remove_filter_or_cow_child_commit, + .clean = g_free, +}; + +/* + * A function to remove backing-chain child of @bs if exists: cow child for + * format nodes (always .backing) and filter child for filters (may be .file or + * .backing) + */ +__attribute__((unused)) +static void bdrv_remove_filter_or_cow_child(BlockDriverState *bs, + Transaction *tran) +{ + BdrvRemoveFilterOrCowChild *s; + BdrvChild *child = bdrv_filter_or_cow_child(bs); + + if (!child) { + return; + } + + if (child->bs) { + bdrv_replace_child_safe(child, NULL, tran); + } + + s = g_new(BdrvRemoveFilterOrCowChild, 1); + *s = (BdrvRemoveFilterOrCowChild) { + .child = child, + .is_backing = (child == bs->backing), + }; + tran_add(tran, &bdrv_remove_filter_or_cow_child_drv, s); + + QLIST_SAFE_REMOVE(child, next); + if (s->is_backing) { + bs->backing = NULL; + } else { + bs->file = NULL; + } +} + static int bdrv_replace_node_noperm(BlockDriverState *from, BlockDriverState *to, bool auto_skip, Transaction *tran,
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> --- block.c | 78 +++++++++++++++++++++++++++++++++++++++++++++++++++++++-- 1 file changed, 76 insertions(+), 2 deletions(-)