Several FUSE ops fell back to looking up a FileInfo via
state.open_files when the kernel-provided fh was zero, returning
-ENOENT if the lookup failed. This path papered over handle-tracking
bugs and added cost on every call. Use the handle directly and
return -EBADF when it is invalid - the kernel should always hand us
a valid fh for an open resource.
Also simplify FileInfo::from_fh / DirInfo::from_fh and their to_fh
helpers: callers now handle the null-pointer case explicitly so the
ASSERT_NOT_NULL checks are redundant.
Covers fallocate, fchmod, fchown, fgetattr, flock, ftruncate,
futimens, read, release, releasedir, write, statx, ioctl (file +
dir), readdir (sequential, concurrent-on-read,
concurrent-on-search), and the passthrough fast paths in
create/open.
Run in an elevated credential mode (root) and let the kernel manage
entitlements. Will result in slightly different behavior but should
not be noticed by most.
Also have special error handling for when branches are invalid and
ENOENT would be returned for getattr and readdir so users understand
what is going on and the runtime interface can still be used to fix
the problem.
* Use concurrent_flat_map to build a global cache rather than per
thread.
* Create global maintanence thread manager for clearing unused cache
entries.
mergerfs tries to pass through ioctl calls but due to the complexity
of btrfs calls their is risk of segfaults. In the future it may be
required to whitelist all supported ioctl calls.
While they were going to be the new way of interacting with the runtime config
I've decided to use toml based config for mergerfs v3. In that case all updates
will happen through the config file and ioctl will only be used to load/reload
the config rather than a key:value like API.
