Messages in this thread | | | Date | Tue, 11 Jul 2023 15:15:29 +0800 | Subject | Re: [PATCH 5/5] docs: fuse: improve FUSE consistency explanation | From | Jiachen Zhang <> |
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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@bytedance.com> >> --- >> 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
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