On 17.09.19 г. 11:31 ч., Niccolò Belli wrote: > Hi, > What happened to the subpagesize-blocksize patchset? It seems to be > untouched since 3 years. > I'm currently stuck on Fedora ppc64le because it ships with a 64k page > size, but I need it to be 4k in order to be able to chroot into foreign > architectures (like x86_64) with qemu-user. > > If I try to mount my btrfs partition with a kernel with page size set to > 4k I get the following error: > > sectorsize 65536 not supported yet, only support 4094 > > I didn't try the patchset, because it doesn't support compression and my > whole fs is compressed. > > It looked like an awesome work, why didn't it get merged? TLDR: It's not ready and likely won't be in the upcoming months. There are a bunch of stuff that need to happen before subpage blocksize support can land in. Namely, the btree inode needs to be removed. Josef has a WIP branch doing that but it in turn is dependent on a new mechanism to support proper writeback throttling of metadata from the superblock. OTOH I have an idea of how to remove the btree indoe by exploiting the existing shrinkers mechanism but that's only a concept and there are some reservations whether it's doable (It is but there are concerns shrinker infrastructure cannot cope with the rate of dirty metadata that btrfs produces.) > > Bests, > Niccolo' >
