If using Linux 6.9 or above and enabled (passthrough=true) files
opened or created will use the FUSE passthrough feature.
If direct-io=true / cache.files=off it will override passthrough. If
direct-io-allow-mmap is enabled only mmap will passthrough.
HANDLE_KILLPRIV and V2 are enabled now by default to remove the
kernel's need to issue getattr and getxattr requests.
moveonenospc will not work when leveraging passthrough.
* Replace the stat values with a crc32b of them instead (for auto-cache)
* Replace char flag with bitfield
* Remove node generation. nodeid is an unsigned 64bit int. Would take 500K+ years
to rollover at 1M nodes per second.
* Remove request interrupt code. Required tracking of all requests unnecesssarily.
* Remove all debugging printing. Have plans to do full replacement.
* Remove deprecated functions.
* Remove unneeded error checking.
* Remove "userdata" which was unused.
* Remove allow_root feature.
* follow-symlinks: allows mergerfs to transparently follow symlinks
* link-exdev: in the event a link returns EXDEV create a symlink instead
* rename-exdev: in the event a rename returns EXDEV move the oldpath and
create a symlink for the newpath
This removes the risk of corrupted data being sent back to the kernel
should it use the offset from one opendir-readdir in another. In this case
it would at most skip dirents.
According to the standards the offset is only valid when used within
the opendir -> releasedir but NFS uses offsets across independent
calls.
Linux 4.20 and above allow setting the number of pages per FUSE message
upto 256 (4K * 256 = 1MiB). This can greatly increase read and write
speeds depending on the workload.