Re: [PATCH 5/5] docs: fuse: improve FUSE consistency explanation

[Jiachen Zhang]

On 2023/7/11 12:42, Randy Dunlap wrote:
> Hi--
>
> On 7/10/23 21:34, Jiachen Zhang wrote:
> > Signed-off-by: Jiachen Zhang <zhangjiachen.jaycee@xxxxxxxxxxxxx>
> > ---
> >   Documentation/filesystems/fuse-io.rst | 32 +++++++++++++++++++++++++--
> >   1 file changed, 30 insertions(+), 2 deletions(-)
> >
> > diff --git a/Documentation/filesystems/fuse-io.rst b/Documentation/filesystems/fuse-io.rst
> > index 255a368fe534..cdd292dd2e9c 100644
> > --- a/Documentation/filesystems/fuse-io.rst
> > +++ b/Documentation/filesystems/fuse-io.rst
>
> > @@ -24,7 +31,8 @@ after any writes to the file.  All mmap modes are supported.
> >   The cached mode has two sub modes controlling how writes are handled.  The
> >   write-through mode is the default and is supported on all kernels.  The
> >   writeback-cache mode may be selected by the FUSE_WRITEBACK_CACHE flag in the
> > -FUSE_INIT reply.
> > +FUSE_INIT reply. In either modes, if the FOPEN_KEEP_CACHE flag is not set in
>
>                         either mode,
>
> > +the FUSE_OPEN, cached pages of the file will be invalidated immediatedly.
>
>                                                                 immediately.
>
> >   
> >   In write-through mode each write is immediately sent to userspace as one or more
> >   WRITE requests, as well as updating any cached pages (and caching previously
> > @@ -38,7 +46,27 @@ reclaim on memory pressure) or explicitly (invoked by close(2), fsync(2) and
> >   when the last ref to the file is being released on munmap(2)).  This mode
> >   assumes that all changes to the filesystem go through the FUSE kernel module
> >   (size and atime/ctime/mtime attributes are kept up-to-date by the kernel), so
> > -it's generally not suitable for network filesystems.  If a partial page is
> > +it's generally not suitable for network filesystems (you can consider the
> > +writeback-cache-v2 mode mentioned latter for them).  If a partial page is
>
>                                       later
>
> >   written, then the page needs to be first read from userspace.  This means, that
> >   even for files opened for O_WRONLY it is possible that READ requests will be
> >   generated by the kernel.


Thanks, Randy. I will fix them in the next version.

Jiachen