Re: [PATCH v2 0/3] block: reject persistent bitmaps a node can never store
Vladimir Sementsov-Ogievskiy <[email protected]>
| Newsgroups | gmane.comp.emulators.qemu,gmane.comp.emulators.qemu.block |
|---|---|
| Message-ID | <[email protected]> |
On 27.07.26 15:05, Denis V. Lunev wrote: > On 7/16/26 13:22, Denis V. Lunev wrote: >> This email originated from an IP that might not be authorized by the domain it was sent from. >> Do not click links or open attachments unless it is an email you expected to receive. >> qmp_block_dirty_bitmap_add() and the incoming-migration bitmap loader >> both create a persistent bitmap with bdrv_create_dirty_bitmap(), which >> always creates it writable, without checking whether the node can >> actually be written to. A persistent bitmap added to an already >> read-only or inactive node stays writable in memory on a node that >> can never store it, and the next global inactivation (migration >> completion, save, or any other bdrv_inactivate_all() caller) fails >> trying to flush it back: >> >> Lost persistent bitmaps during inactivation of node '<node>': No write access >> migration_block_inactivate: bdrv_inactivate_all() failed: -22 >> >> Patch 1 rejects this at block-dirty-bitmap-add (and, wrapped in a >> transaction, denies the whole transaction). Patch 2 closes the same >> hole on the incoming-migration path. Patch 3 fixes a knock-on >> regression from patch 1's approach: a bitmap that was rejected from >> ever being written can still exist in memory read-only and must >> remain removable without requiring write access. >> >> v1 -> v2 >> * approach changed to deny rather than adopt (Vladimir) >> * added patch to add permission check on migration path >> * added patch to change permissions check on bitmap drop to more natural >> >> Signed-off-by: Denis V. Lunev <[email protected]> >> CC: Eric Blake <[email protected]> >> CC: Vladimir Sementsov-Ogievskiy <[email protected]> >> CC: John Snow <[email protected]> >> CC: Andrey Drobyshev <[email protected]> >> >> Denis V. Lunev (3): >> block/monitor: reject persistent bitmap add on a read-only node >> migration/block-dirty-bitmap: reject bitmap load onto ro node >> block/monitor: allow dropping a bitmap never stored on disk >> >> block/monitor/bitmap-qmp-cmds.c | 19 +++++++---- >> block/qcow2-bitmap.c | 9 +++++ >> migration/block-dirty-bitmap.c | 22 +++++++++---- >> qapi/block-core.json | 4 ++- >> tests/qemu-iotests/tests/migrate-bitmaps-test | 33 +++++++++++++++++++ >> .../tests/migrate-bitmaps-test.out | 4 +-- >> .../tests/remove-bitmap-from-backing | 29 +++++++++++++++- >> .../tests/remove-bitmap-from-backing.out | 22 ++++++++++++- >> 8 files changed, 124 insertions(+), 18 deletions(-) >> > Hi, Vladimir! > > Will this go through your tree? It is looking like nobody else cares. > Yes, seems so. Thanks, applied to my block branch. There's still a chance to stop me within 2-3 weeks before 11.2 cycle opens. -- Best regards, Vladimir