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. -- Thanks, Jeffle
