On Tue, 19 Mar 2024 at 17:54, Jeff Layton <jlayton@xxxxxxxxxx> wrote: > > Traditionally, we've allowed people to set leases on FUSE inodes. Some > FUSE drivers are effectively local filesystems and should be fine with > kernel-internal lease support. But others are backed by a network server > that may have multiple clients, or may be backed by something non-file > like entirely. > > Have the filesytem driver to set a fuse_conn flag to indicate whether it > wants support for local, in-kernel leases. If the flag is unset (the > default), then setlease attempts will fail with -EINVAL, indicating that > leases aren't supported on that inode. > > Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx> > --- > This is only tested for compilation, but it's fairly straightforward. > Having the FUSE drivers opt-out of this support might be more > backward-compatible, but that is a bit more dangerous. I'd rather driver > maintainer consciously opt-in. In the end the lease behavior will need to be reverted if there are regressions. I really don't know which is worse, the risk of regressions or the of risk data corruption... Also I'd prefer a more general flag indicating that the the kernel driver can assume no external changes to the filesystem. E.g. FUSE_NO_OUTSIDE_CHANGE. Does this make sense? Can you imagine a case where FUSE_LOCAL_LEASES would be set, but caching policy would not assume no external changes? Thanks, Miklos
