1 files changed, 50 insertions, 6 deletions

diff --git a/fs/nfsd/nfsfh.c b/fs/nfsd/nfsfh.c
index 739dd3c5c3b2..6ca2d24fc216 100644
--- a/fs/nfsd/nfsfh.c
+++ b/fs/nfsd/nfsfh.c
@@ -323,7 +323,7 @@ fh_compose(struct svc_fh *fhp, struct svc_export *exp, struct dentry *dentry,
          *
          */
 
-        u8 version = 1;
+        u8 version;
         u8 fsid_type = 0;
         struct inode * inode = dentry->d_inode;
         struct dentry *parent = dentry->d_parent;
@@ -341,15 +341,59 @@ fh_compose(struct svc_fh *fhp, struct svc_export *exp, struct dentry *dentry,
          * the reference filehandle (if it is in the same export)
          * or the export options.
          */
+ retry:
+        version = 1;
         if (ref_fh && ref_fh->fh_export == exp) {
                 version = ref_fh->fh_handle.fh_version;
-                if (version == 0xca)
+                fsid_type = ref_fh->fh_handle.fh_fsid_type;
+
+                if (ref_fh == fhp)
+                        fh_put(ref_fh);
+                ref_fh = NULL;
+
+                switch (version) {
+                case 0xca:
                         fsid_type = FSID_DEV;
-                else
-                        fsid_type = ref_fh->fh_handle.fh_fsid_type;
-                /* We know this version/type works for this export
-                 * so there is no need for further checks.
+                        break;
+                case 1:
+                        break;
+                default:
+                        goto retry;
+                }
+
+                /* Need to check that this type works for this
+                 * export point.  As the fsid -> filesystem mapping
+                 * was guided by user-space, there is no guarantee
+                 * that the filesystem actually supports that fsid
+                 * type. If it doesn't we loop around again without
+                 * ref_fh set.
                  */
+                switch(fsid_type) {
+                case FSID_DEV:
+                        if (!old_valid_dev(ex_dev))
+                                goto retry;
+                        /* FALL THROUGH */
+                case FSID_MAJOR_MINOR:
+                case FSID_ENCODE_DEV:
+                        if (!(exp->ex_dentry->d_inode->i_sb->s_type->fs_flags
+                              & FS_REQUIRES_DEV))
+                                goto retry;
+                        break;
+                case FSID_NUM:
+                        if (! (exp->ex_flags & NFSEXP_FSID))
+                                goto retry;
+                        break;
+                case FSID_UUID8:
+                case FSID_UUID16:
+                        if (!root_export)
+                                goto retry;
+                        /* fall through */
+                case FSID_UUID4_INUM:
+                case FSID_UUID16_INUM:
+                        if (exp->ex_uuid == NULL)
+                                goto retry;
+                        break;
+                }
         } else if (exp->ex_uuid) {
                 if (fhp->fh_maxsize >= 64) {
                         if (root_export)