Did you mean to mark this as [PULL] ? On 12/9/19 11:16 AM, Eric Blake wrote: > From: Vladimir Sementsov-Ogievskiy <[email protected]> > > Here is double bug: > > First, return error but not set errp. This may lead to: > qmp block-dirty-bitmap-remove may report success when actually failed > > block-dirty-bitmap-remove used in a transaction will crash, as > qmp_transaction will think that it returned success and will call > block_dirty_bitmap_remove_commit which will crash, as state->bitmap is > NULL > > Second (like in anecdote), this case is not an error at all. As it is > documented in the comment above bdrv_co_remove_persistent_dirty_bitmap > definition, absence of bitmap is not an error, and similar case handled > at start of qcow2_co_remove_persistent_dirty_bitmap, it returns 0 when > there is no bitmaps at all. > > But when there are some bitmaps, but not the requested one, it return > error with errp unset. > > Fix that. > > Trigger: > 1. create persistent bitmap A > 2. shutdown vm (bitmap A is synced) > 3. start vm > 4. create persistent bitmap B > 5. remove bitmap B - it fails (and crashes if in transaction) > > Potential workaround (rather invasive to ask clients to implement it): > 1. create persistent bitmap A > 2. shutdown vm > 3. start vm > 4. create persistent bitmap B > 5. remember, that we want to remove bitmap B after vm shutdown > ... > some other operations > ... > 6. vm shutdown > 7. start vm in stopped mode, and remove all bitmaps marked for removing > 8. stop vm > > Fixes: b56a1e31759b750 > Signed-off-by: Vladimir Sementsov-Ogievskiy <[email protected]> > Message-Id: <[email protected]> > Reviewed-by: Eric Blake <[email protected]> > Reviewed-by: John Snow <[email protected]> > [eblake: commit message tweaks] > Signed-off-by: Eric Blake <[email protected]> > --- > block/qcow2-bitmap.c | 9 ++++++--- > 1 file changed, 6 insertions(+), 3 deletions(-) > > diff --git a/block/qcow2-bitmap.c b/block/qcow2-bitmap.c > index 8abaf632fc7d..c6c8ebbe89d4 100644 > --- a/block/qcow2-bitmap.c > +++ b/block/qcow2-bitmap.c > @@ -1469,8 +1469,10 @@ int coroutine_fn > qcow2_co_remove_persistent_dirty_bitmap(BlockDriverState *bs, > Qcow2BitmapList *bm_list; > > if (s->nb_bitmaps == 0) { > - /* Absence of the bitmap is not an error: see explanation above > - * bdrv_remove_persistent_dirty_bitmap() definition. */ > + /* > + * Absence of the bitmap is not an error: see explanation above > + * bdrv_co_remove_persistent_dirty_bitmap() definition. > + */ > return 0; > } > > @@ -1485,7 +1487,8 @@ int coroutine_fn > qcow2_co_remove_persistent_dirty_bitmap(BlockDriverState *bs, > > bm = find_bitmap_by_name(bm_list, name); > if (bm == NULL) { > - ret = -EINVAL; > + /* Absence of the bitmap is not an error, see above. */ > + ret = 0; > goto out; > } >
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