Before this change rclone marked files opened for write without VFS
cache with the non seekable flag.
This caused problems with rclone mount layerd with mergerfs.
This change removes the hint and lets rclone do all the checking for
seekability.
By default bazil fuse will return ENOTSUPP for these. However if we
return ENOSYS then OSXFUSE (at least) will never call them again
saving round trips though fuse.
Previously this was adding it in to all file opens which was causing
inefficiencies under Windows where it stats the file using
open/fstat/close.
This change will make stat operations run much quicker under Windows
as they won't have to open the underlying file
This problem was introduced in61b6159a05336bd7ba105766de2d2ff171f7fb81
where we added O_CREATE to all file opens and creates.
This flag allows the attribute caching in the kernel to be controlled.
The default is 0s - no caching - which is recommended for filesystems
which can change outside the control of the kernel.
Previously this was at the default meaning it was 60s for mount and 1s
for cmount. This showed strange effects when files changed on the
remote not via the kernel. For instance Caddy would serve corrupted
files for a while when serving from an rclone mount when a file
changed on the remote.
The purpose of this is to make it easier to maintain and eventually to
allow the rclone backends to be re-used in other projects without
having to use the rclone configuration system.
The new code layout is documented in CONTRIBUTING.
* Tests for VFS layer
* Small fixes found during testing
* Fix Close, Flush and Release behaviour for ReadFileHandle and WriteFileHandle
* Fix nil object bugs on File
