[Virtio-fs] [PATCH v7 6/7] fuse: mark inode DONT_CACHE when per inode DAX hint changes

[Miklos Szeredi]

On Tue, 2 Nov 2021 at 06:26, Jeffle Xu <jefflexu at linux.alibaba.com> wrote:
>
> When the per inode DAX hint changes while the file is still *opened*, it
> is quite complicated and maybe fragile to dynamically change the DAX
> state.
>
> Hence mark the inode and corresponding dentries as DONE_CACHE once the
> per inode DAX hint changes, so that the inode instance will be evicted
> and freed as soon as possible once the file is closed and the last
> reference to the inode is put. And then when the file gets reopened next
> time, the new instantiated inode will reflect the new DAX state.
>
> In summary, when the per inode DAX hint changes for an *opened* file, the
> DAX state of the file won't be updated until this file is closed and
> reopened later.

This patch does nothing, since fuse already uses .drop_inode =
generic_delete_inode, which is has the same effect as setting
I_DONTCACHE, at least in the fuse case (inode should never be dirty at
eviction).   In fact it may be cleaner to set I_DONTCACHE
unconditionally and remove the .drop_inode callback setting.

Thanks,
Miklos