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.
--
~Randy
