On Wed, Oct 20, 2021 at 11:10:30AM +0800, JeffleXu wrote: > > > On 10/18/21 10:30 PM, Vivek Goyal wrote: > > On Mon, Oct 11, 2021 at 11:00:49AM +0800, Jeffle Xu wrote: > >> Among the FUSE_INIT phase, client shall advertise per-file DAX if it's > >> mounted with "-o dax=inode". Then server is aware that client is in > >> per-file DAX mode, and will construct per-inode DAX attribute > >> accordingly. > >> > >> Signed-off-by: Jeffle Xu <jefflexu@xxxxxxxxxxxxxxxxx> > >> --- > >> fs/fuse/inode.c | 2 ++ > >> 1 file changed, 2 insertions(+) > >> > >> diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c > >> index b4b41683e97e..f4ad99e2415b 100644 > >> --- a/fs/fuse/inode.c > >> +++ b/fs/fuse/inode.c > >> @@ -1203,6 +1203,8 @@ void fuse_send_init(struct fuse_mount *fm) > >> #ifdef CONFIG_FUSE_DAX > >> if (fm->fc->dax) > >> ia->in.flags |= FUSE_MAP_ALIGNMENT; > >> + if (fm->fc->dax_mode == FUSE_DAX_INODE) > >> + ia->in.flags |= FUSE_PERFILE_DAX; > > > > Are you not keeping track of server's response whether server supports > > per inode dax or not. Client might be new and server might be old and > > server might not support per inode dax. In that case, we probably > > should error out if user mounted with "-o dax=inode". > > > > Yes, if guest virtiofs is mounted with '-o dax=inode' while virtiofsd is > old and doesn't support per inode dax, then guest virtiofs will never > receive FUSE_ATTR_DAX and actually behaves as '-o dax=never'. So the > whole system works in this case, though the behavior may be beyond the > expectation of users .... > > If the behavior really matters, I could change the behavior and fail > directly if virtiofsd doesn't advertise supporting per inode DAX. I think it probably is better to error out if client asked for per-inode DAX and server does not support it. Vivek > > -- > Thanks, > Jeffle >
