cifs: clean up handling when server doesn't consistently support inode numbers

It's possible that a server will return a valid FileID when we query the
FILE_INTERNAL_INFO for the root inode, but then zeroed out inode numbers
when we do a FindFile with an infolevel of
SMB_FIND_FILE_ID_FULL_DIR_INFO.

In this situation turn off querying for server inode numbers, generate a
warning for the user and just generate an inode number using iunique.
Once we generate any inode number with iunique we can no longer use any
server inode numbers or we risk collisions, so ensure that we don't do
that in cifs_get_inode_info either.

Cc: Stable <stable@kernel.org>
Reported-by: Timothy Normand Miller <theosib@gmail.com>
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Steve French <sfrench@us.ibm.com>

fs/cifs/cifsproto.h

@@ -388,4 +388,5 @@ extern int CIFSSMBSetPosixACL(const int xid, struct cifsTconInfo *tcon,
 		const struct nls_table *nls_codepage, int remap_special_chars);
 extern int CIFSGetExtAttr(const int xid, struct cifsTconInfo *tcon,
 			const int netfid, __u64 *pExtAttrBits, __u64 *pMask);
+extern void cifs_autodisable_serverino(struct cifs_sb_info *cifs_sb);
 #endif			/* _CIFSPROTO_H */

fs/cifs/inode.c

@@ -512,13 +512,10 @@ int cifs_get_inode_info(struct inode **pinode,
 					cifs_sb->local_nls,
 					cifs_sb->mnt_cifs_flags &
 						CIFS_MOUNT_MAP_SPECIAL_CHR);
-			if (rc1) {
+			if (rc1 || !fattr.cf_uniqueid) {
 				cFYI(1, ("GetSrvInodeNum rc %d", rc1));
 				fattr.cf_uniqueid = iunique(sb, ROOT_I);
-				/* disable serverino if call not supported */
-				if (rc1 == -EINVAL)
-					cifs_sb->mnt_cifs_flags &=
-							~CIFS_MOUNT_SERVER_INUM;
+				cifs_autodisable_serverino(cifs_sb);
 			}
 		} else {
 			fattr.cf_uniqueid = iunique(sb, ROOT_I);

fs/cifs/misc.c

@@ -715,3 +715,17 @@ cifsConvertToUCS(__le16 *target, const char *source, int maxlen,
 ctoUCS_out:
 	return i;
 }
+
+void
+cifs_autodisable_serverino(struct cifs_sb_info *cifs_sb)
+{
+	if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_SERVER_INUM) {
+		cifs_sb->mnt_cifs_flags &= CIFS_MOUNT_SERVER_INUM;
+		cERROR(1, ("Autodisabling the use of server inode numbers on "
+			   "%s. This server doesn't seem to support them "
+			   "properly. Hardlinks will not be recognized on this "
+			   "mount. Consider mounting with the \"noserverino\" "
+			   "option to silence this message.",
+			   cifs_sb->tcon->treeName));
+	}
+}

fs/cifs/readdir.c

@@ -727,11 +727,12 @@ static int cifs_filldir(char *pfindEntry, struct file *file, filldir_t filldir,
 		cifs_dir_info_to_fattr(&fattr, (FILE_DIRECTORY_INFO *)
 					pfindEntry, cifs_sb);
 
-	/* FIXME: make _to_fattr functions fill this out */
-	if (pCifsF->srch_inf.info_level == SMB_FIND_FILE_ID_FULL_DIR_INFO)
+	if (inum && (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_SERVER_INUM)) {
 		fattr.cf_uniqueid = inum;
-	else
+	} else {
 		fattr.cf_uniqueid = iunique(sb, ROOT_I);
+		cifs_autodisable_serverino(cifs_sb);
+	}
 
 	ino = cifs_uniqueid_to_ino_t(fattr.cf_uniqueid);
 	tmp_dentry = cifs_readdir_lookup(file->f_dentry, &qstring, &fattr);