ovl: set i_ino to the value of st_ino for NFS export
Eddie Horng reported that readdir of an overlayfs directory that
was exported via NFSv3 returns entries with d_type set to DT_UNKNOWN.
The reason is that while preparing the response for readdirplus, nfsd
checks inside encode_entryplus_baggage() that a child dentry's inode
number matches the value of d_ino returns by overlayfs readdir iterator.
Because the overlayfs inodes use arbitrary inode numbers that are not
correlated with the values of st_ino/d_ino, NFSv3 falls back to not
encoding d_type. Although this is an allowed behavior, we can fix it for
the case of all overlayfs layers on the same underlying filesystem.
When NFS export is enabled and d_ino is consistent with st_ino
(samefs), set the same value also to i_ino in ovl_fill_inode() for all
overlayfs inodes, nfsd readdirplus sanity checks will pass.
ovl_fill_inode() may be called from ovl_new_inode(), before real inode
was created with ino arg 0. In that case, i_ino will be updated to real
upper inode i_ino on ovl_inode_init() or ovl_inode_update().
Reported-by: Eddie Horng <eddiehorng.tw@gmail.com>
Tested-by: Eddie Horng <eddiehorng.tw@gmail.com>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Fixes: 8383f1748829 ("ovl: wire up NFS export operations")
Cc: <stable@vger.kernel.org> #v4.16
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
diff --git a/fs/overlayfs/util.c b/fs/overlayfs/util.c
index 930784a..493f9b7 100644
--- a/fs/overlayfs/util.c
+++ b/fs/overlayfs/util.c
@@ -279,12 +279,16 @@ void ovl_dentry_set_redirect(struct dentry *dentry, const char *redirect)
void ovl_inode_init(struct inode *inode, struct dentry *upperdentry,
struct dentry *lowerdentry)
{
+ struct inode *realinode = d_inode(upperdentry ?: lowerdentry);
+
if (upperdentry)
OVL_I(inode)->__upperdentry = upperdentry;
if (lowerdentry)
OVL_I(inode)->lower = igrab(d_inode(lowerdentry));
- ovl_copyattr(d_inode(upperdentry ?: lowerdentry), inode);
+ ovl_copyattr(realinode, inode);
+ if (!inode->i_ino)
+ inode->i_ino = realinode->i_ino;
}
void ovl_inode_update(struct inode *inode, struct dentry *upperdentry)
@@ -299,6 +303,8 @@ void ovl_inode_update(struct inode *inode, struct dentry *upperdentry)
smp_wmb();
OVL_I(inode)->__upperdentry = upperdentry;
if (inode_unhashed(inode)) {
+ if (!inode->i_ino)
+ inode->i_ino = upperinode->i_ino;
inode->i_private = upperinode;
__insert_inode_hash(inode, (unsigned long) upperinode);
}