addresses #521
mergerfs is written using libfuse's high level API. The HLAPI forces a certain
behavior with regard to unlinking or rename overwriting of open files. It
renames the file to .fuse_hiddenXXXXXX and when incoming requests refer
to the unlinked file it will use path based calls and use that path.
This behavior leads to rmdirs failing or some software noticing
the .fuse_hidden files.
This patch changes the HLAPI and removes entirely the .fuse_hidden behavior.
See the README for more.
`defaults` is a value used by all filesystems and isn't passed through to
mergerfs when mounting via the fstab or the mount command. This led
to inconsistent application of options. atomic_o_trunc, big_writes, and
default_permissions should be enabled all the time anyway and splice_*
can lead to issues so they are not always enabled.
This allows users to tag a branch as readonly or not for writing regardless
of how the filesystem is mounted. Should simplify deployments and offer
more flexibility.
If available FICLONE and copy_file_range will be tried in addition to sendfile
when copying data between two files. The fallback is a tradition read/write
loop. On systems that support these it should improve performance.
When enabled if a regular file is opened which has a link count > 1 it will
copy the file to a temporary file and rename over the original. Effectively
breaking the link. This behavior is similar to cow-shell and other LD_PRELOAD
based "CoW" solutions.
Parsing of and acting upon "-o threads" option is done in the bundled `libfuse/`,
so move the corresponding help text there too.
This make help text consistent with behavior
when building against system libfuse,
which doesn't support this option.
