NFSD: Add a cache for fs_locations information

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
[ cel: since this is server-side, use nfsd4_ prefix instead of nfs4_ prefix. ]
[ cel: implement S_ISVTX filter in bfields-normal form ]
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Reviewed-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

2 files changed, 25 insertions, 0 deletions

diff --git a/fs/nfsd/nfsd.h b/fs/nfsd/nfsd.h
index 8da03e16ab35..58134a23fdfb 100644
--- a/fs/nfsd/nfsd.h
+++ b/fs/nfsd/nfsd.h
@@ -361,6 +361,13 @@ static inline u32 nfsd_suppattrs2(u32 minorversion)
 #define NFSD_SUPPATTR_EXCLCREAT_WORD2 \
         NFSD_WRITEABLE_ATTRS_WORD2
 
+extern int nfsd4_is_junction(struct dentry *dentry);
+#else
+static inline int nfsd4_is_junction(struct dentry *dentry)
+{
+        return 0;
+}
+
 #endif /* CONFIG_NFSD_V4 */
 
 #endif /* LINUX_NFSD_NFSD_H */
diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c
index 75c35fa46155..4dd91283d039 100644
--- a/fs/nfsd/vfs.c
+++ b/fs/nfsd/vfs.c
@@ -168,6 +168,8 @@ int nfsd_mountpoint(struct dentry *dentry, struct svc_export *exp)
 {
         if (d_mountpoint(dentry))
                 return 1;
+        if (nfsd4_is_junction(dentry))
+                return 1;
         if (!(exp->ex_flags & NFSEXP_V4ROOT))
                 return 0;
         return dentry->d_inode != NULL;
@@ -592,6 +594,22 @@ nfsd4_get_nfs4_acl(struct svc_rqst *rqstp, struct dentry *dentry, struct nfs4_ac
         return error;
 }
 
+#define NFSD_XATTR_JUNCTION_PREFIX XATTR_TRUSTED_PREFIX "junction."
+#define NFSD_XATTR_JUNCTION_TYPE NFSD_XATTR_JUNCTION_PREFIX "type"
+int nfsd4_is_junction(struct dentry *dentry)
+{
+        struct inode *inode = dentry->d_inode;
+
+        if (inode == NULL)
+                return 0;
+        if (inode->i_mode & S_IXUGO)
+                return 0;
+        if (!(inode->i_mode & S_ISVTX))
+                return 0;
+        if (vfs_getxattr(dentry, NFSD_XATTR_JUNCTION_TYPE, NULL, 0) <= 0)
+                return 0;
+        return 1;
+}
 #endif /* defined(CONFIG_NFSD_V4) */
 
 #ifdef CONFIG_NFSD_V3