On Fri, Jan 31, 2020 at 12:50:04PM +0100, Miklos Szeredi wrote: > No reason to prevent upper layer being a remote filesystem. Do the > revalidation in that case, just as we already do for lower layers. > > This lets virtiofs be used as upper layer, which appears to be a real use > case. Hi Miklos, I have couple of very basic questions. - So with this change, we will allow NFS to be upper layer also? - What does revalidation on lower/upper mean? Does that mean that lower/upper can now change underneath overlayfs and overlayfs will cope with it. If we still expect underlying layers not to change, then what's the point of calling ->revalidate(). Thanks Vivek > > Signed-off-by: Miklos Szeredi <mszeredi@xxxxxxxxxx> > --- > fs/overlayfs/namei.c | 3 +-- > fs/overlayfs/super.c | 8 ++++++-- > fs/overlayfs/util.c | 2 ++ > 3 files changed, 9 insertions(+), 4 deletions(-) > > diff --git a/fs/overlayfs/namei.c b/fs/overlayfs/namei.c > index 76e61cc27822..0db23baf98e7 100644 > --- a/fs/overlayfs/namei.c > +++ b/fs/overlayfs/namei.c > @@ -845,8 +845,7 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry, > if (err) > goto out; > > - if (upperdentry && (upperdentry->d_flags & DCACHE_OP_REAL || > - unlikely(ovl_dentry_remote(upperdentry)))) { > + if (upperdentry && upperdentry->d_flags & DCACHE_OP_REAL) { > dput(upperdentry); > err = -EREMOTE; > goto out; > diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c > index 26d4153240a8..ed3a11db9039 100644 > --- a/fs/overlayfs/super.c > +++ b/fs/overlayfs/super.c > @@ -135,9 +135,14 @@ static int ovl_dentry_revalidate_common(struct dentry *dentry, > unsigned int flags, bool weak) > { > struct ovl_entry *oe = dentry->d_fsdata; > + struct dentry *upper; > unsigned int i; > int ret = 1; > > + upper = ovl_dentry_upper(dentry); > + if (upper) > + ret = ovl_revalidate_real(upper, flags, weak); > + > for (i = 0; ret > 0 && i < oe->numlower; i++) { > ret = ovl_revalidate_real(oe->lowerstack[i].dentry, flags, > weak); > @@ -747,8 +752,7 @@ static int ovl_mount_dir(const char *name, struct path *path) > ovl_unescape(tmp); > err = ovl_mount_dir_noesc(tmp, path); > > - if (!err && (ovl_dentry_remote(path->dentry) || > - path->dentry->d_flags & DCACHE_OP_REAL)) { > + if (!err && path->dentry->d_flags & DCACHE_OP_REAL) { > pr_err("filesystem on '%s' not supported as upperdir\n", > tmp); > path_put_init(path); > diff --git a/fs/overlayfs/util.c b/fs/overlayfs/util.c > index 3ad8fb291f7d..c793722739e1 100644 > --- a/fs/overlayfs/util.c > +++ b/fs/overlayfs/util.c > @@ -96,6 +96,8 @@ void ovl_dentry_update_reval(struct dentry *dentry, struct dentry *upperdentry, > struct ovl_entry *oe = OVL_E(dentry); > unsigned int i, flags = 0; > > + if (upperdentry) > + flags |= upperdentry->d_flags; > for (i = 0; i < oe->numlower; i++) > flags |= oe->lowerstack[i].dentry->d_flags; > > -- > 2.21.1 >