On Fri, Aug 21, 2020 at 11:41:26AM +0800, Jiachen Zhang wrote: > Due to the commit 65da4539803373ec4eec97ffc49ee90083e56efd, the O_DIRECT > open flag of guest applications will be discarded by virtiofsd. While > this behavior makes it consistent with the virtio-9p scheme when guest > applications using direct I/O, we no longer have any chance to bypass > the host page cache. > > Therefore, we add a flag 'allow_directio' to lo_data. If '-o no_directio' > option is added, or none of '-o no_directio' or '-o allow_directio' is > added, the 'allow_directio' will be set to 0, and virtiofsd discards > O_DIRECT as before. If '-o allow_directio' is added to the stariting > command-line, 'allow_directio' will be set to 1, so that the O_DIRECT > flags will be retained and host page cache can be bypassed. > > Signed-off-by: Jiachen Zhang <zhangjiachen.jay...@bytedance.com> > --- > tools/virtiofsd/helper.c | 4 ++++ > tools/virtiofsd/passthrough_ll.c | 20 ++++++++++++++------ > 2 files changed, 18 insertions(+), 6 deletions(-) > > diff --git a/tools/virtiofsd/helper.c b/tools/virtiofsd/helper.c > index 3105b6c23a..534ff52c64 100644 > --- a/tools/virtiofsd/helper.c > +++ b/tools/virtiofsd/helper.c > @@ -180,6 +180,10 @@ void fuse_cmdline_help(void) > " (0 leaves rlimit unchanged)\n" > " default: min(1000000, fs.file-max > - 16384)\n" > " if the current rlimit is > lower\n" > + " -o allow_directio|no_directio\n" > + " retain/discard O_DIRECT flags > passed down\n" > + " to virtiofsd from guest > applications.\n" > + " default: no_directio\n" > );
The standard naming convention from existing options is to use $OPTNAME and no_$OPTNAME. IOW, don't use the "allow_" prefix. The options should be just "directio" and "no_directio" Regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|
