On Tue, Aug 20, 2019 at 02:07:37PM +0900, Naohiro Aota wrote: > >>>>cannot be located over sequential zones and there is no guarantees that the > >>>>device will have enough conventional zones to store this cache. Resolve > >>>>this problem by disabling completely the space cache. This does not > >>>>introduces any problems with sequential block groups: all the free space is > >>>>located after the allocation pointer and no free space before the pointer. > >>>>There is no need to have such cache. > >>>> > >>>>For the same reason, NODATACOW is also disabled. > >>>> > >>>>Also INODE_MAP_CACHE is also disabled to avoid preallocation in the > >>>>INODE_MAP_CACHE inode. > >>> > >>> A list of incompatibility features with zoned devices. This need better > >>> documentation, may be a table and its reason is better. > >> > >>Are you referring to the format of the commit message itself ? Or would you like > >>to see a documentation added to Documentation/filesystems/btrfs.txt ? > > > > Documenting in the commit change log is fine. But it can be better > > documented in a listed format as it looks like we have a list of > > features which will be incompatible with zoned devices. > > > >more below.. > > Sure. I will add a table in the next version. > > btrfs.txt seems not to have much there. We don't use the in-kernel documentation, it's either the wiki or the manual pages in btrfs-progs. The section 5 page contains some generic topics, eg. the swapfile limitations are there.
