cifs: Properly handle auto disabling of serverino option

[ Upstream commit 29fbeb7a ]

Fix mount options comparison when serverino option is turned off later
in cifs_autodisable_serverino() and thus avoiding mismatch of new cifs
mounts.

Cc: stable@vger.kernel.org
Signed-off-by: Paulo Alcantara (SUSE) <paulo@paulo.ac>
Signed-off-by: Steve French <stfrench@microsoft.com>
Reviewed-by: Pavel Shilovsky <pshilove@microsoft.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

fs/cifs/cifs_fs_sb.h

@@ -72,5 +72,10 @@ struct cifs_sb_info {
 	struct delayed_work prune_tlinks;
 	struct rcu_head rcu;
 	char *prepath;
+	/*
+	 * Indicate whether serverino option was turned off later
+	 * (cifs_autodisable_serverino) in order to match new mounts.
+	 */
+	bool mnt_cifs_serverino_autodisabled;
 };
 #endif				/* _CIFS_FS_SB_H */

fs/cifs/connect.c

@@ -3247,12 +3247,16 @@ compare_mount_options(struct super_block *sb, struct cifs_mnt_data *mnt_data)
 {
 	struct cifs_sb_info *old = CIFS_SB(sb);
 	struct cifs_sb_info *new = mnt_data->cifs_sb;
+	unsigned int oldflags = old->mnt_cifs_flags & CIFS_MOUNT_MASK;
+	unsigned int newflags = new->mnt_cifs_flags & CIFS_MOUNT_MASK;
 
 	if ((sb->s_flags & CIFS_MS_MASK) != (mnt_data->flags & CIFS_MS_MASK))
 		return 0;
 
-	if ((old->mnt_cifs_flags & CIFS_MOUNT_MASK) !=
-	    (new->mnt_cifs_flags & CIFS_MOUNT_MASK))
+	if (old->mnt_cifs_serverino_autodisabled)
+		newflags &= ~CIFS_MOUNT_SERVER_INUM;
+
+	if (oldflags != newflags)
 		return 0;
 
 	/*

fs/cifs/misc.c

@@ -523,6 +523,7 @@ 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;
+		cifs_sb->mnt_cifs_serverino_autodisabled = true;
 		cifs_dbg(VFS, "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.\n",
 			 cifs_sb_master_tcon(cifs_sb)->treeName);
 	}