ocfs2: Add incompatible flag for extended attribute

This patch adds the s_incompat flag for extended attribute support. This
helps us ensure that older versions of Ocfs2 or ocfs2-tools will not be able
to mount a volume with xattr support.
Signed-off-by: Tiger Yang <tiger.yang@oracle.com>
Signed-off-by: Mark Fasheh <mfasheh@suse.com>

fs/ocfs2/ocfs2.h

@@ -363,6 +363,13 @@ static inline int ocfs2_supports_inline_data(struct ocfs2_super *osb)
 	return 0;
 }
 
+static inline int ocfs2_supports_xattr(struct ocfs2_super *osb)
+{
+	if (osb->s_feature_incompat & OCFS2_FEATURE_INCOMPAT_XATTR)
+		return 1;
+	return 0;
+}
+
 /* set / clear functions because cluster events can make these happen
  * in parallel so we want the transitions to be atomic. this also
  * means that any future flags osb_flags must be protected by spinlock

fs/ocfs2/ocfs2_fs.h

@@ -91,7 +91,8 @@
 					 | OCFS2_FEATURE_INCOMPAT_SPARSE_ALLOC \
 					 | OCFS2_FEATURE_INCOMPAT_INLINE_DATA \
 					 | OCFS2_FEATURE_INCOMPAT_EXTENDED_SLOT_MAP \
-					 | OCFS2_FEATURE_INCOMPAT_USERSPACE_STACK)
+					 | OCFS2_FEATURE_INCOMPAT_USERSPACE_STACK \
+					 | OCFS2_FEATURE_INCOMPAT_XATTR)
 #define OCFS2_FEATURE_RO_COMPAT_SUPP	OCFS2_FEATURE_RO_COMPAT_UNWRITTEN
 
 /*
@@ -128,10 +129,6 @@
 /* Support for data packed into inode blocks */
 #define OCFS2_FEATURE_INCOMPAT_INLINE_DATA	0x0040
 
-/* Support for the extended slot map */
-#define OCFS2_FEATURE_INCOMPAT_EXTENDED_SLOT_MAP 0x100
-
-
 /*
  * Support for alternate, userspace cluster stacks.  If set, the superblock
  * field s_cluster_info contains a tag for the alternate stack in use as
@@ -143,6 +140,12 @@
  */
 #define OCFS2_FEATURE_INCOMPAT_USERSPACE_STACK	0x0080
 
+/* Support for the extended slot map */
+#define OCFS2_FEATURE_INCOMPAT_EXTENDED_SLOT_MAP 0x100
+
+/* Support for extended attributes */
+#define OCFS2_FEATURE_INCOMPAT_XATTR		0x0200
+
 /*
  * backup superblock flag is used to indicate that this volume
  * has backup superblocks.
@@ -578,7 +581,11 @@ struct ocfs2_super_block {
 /*A0*/  struct ocfs2_cluster_info s_cluster_info; /* Selected userspace
 						     stack.  Only valid
 						     with INCOMPAT flag. */
-/*B8*/  __le64 s_reserved2[17];		/* Fill out superblock */
+/*B8*/	__le16 s_xattr_inline_size;	/* extended attribute inline size
+					   for this fs*/
+	__le16 s_reserved0;
+	__le32 s_reserved1;
+/*C0*/  __le64 s_reserved2[16];		/* Fill out superblock */
 /*140*/
 
 	/*

fs/ocfs2/super.c

@@ -1437,7 +1437,8 @@ static int ocfs2_initialize_super(struct super_block *sb,
 
 	osb->slot_num = OCFS2_INVALID_SLOT;
 
-	osb->s_xattr_inline_size = OCFS2_MIN_XATTR_INLINE_SIZE;
+	osb->s_xattr_inline_size = le16_to_cpu(
+					di->id2.i_super.s_xattr_inline_size);
 
 	osb->local_alloc_state = OCFS2_LA_UNUSED;
 	osb->local_alloc_bh = NULL;

fs/ocfs2/xattr.c

@@ -564,6 +564,9 @@ ssize_t ocfs2_listxattr(struct dentry *dentry,
 	struct ocfs2_dinode *di = NULL;
 	struct ocfs2_inode_info *oi = OCFS2_I(dentry->d_inode);
 
+	if (!ocfs2_supports_xattr(OCFS2_SB(dentry->d_sb)))
+		return -EOPNOTSUPP;
+
 	if (!(oi->ip_dyn_features & OCFS2_HAS_XATTR_FL))
 		return ret;
 
@@ -843,6 +846,9 @@ int ocfs2_xattr_get(struct inode *inode,
 		.not_found = -ENODATA,
 	};
 
+	if (!ocfs2_supports_xattr(OCFS2_SB(inode->i_sb)))
+		return -EOPNOTSUPP;
+
 	if (!(oi->ip_dyn_features & OCFS2_HAS_XATTR_FL))
 		ret = -ENODATA;
 
@@ -1541,6 +1547,9 @@ int ocfs2_xattr_remove(struct inode *inode, struct buffer_head *di_bh)
 	handle_t *handle;
 	int ret;
 
+	if (!ocfs2_supports_xattr(OCFS2_SB(inode->i_sb)))
+		return 0;
+
 	if (!(oi->ip_dyn_features & OCFS2_HAS_XATTR_FL))
 		return 0;
 
@@ -1977,6 +1986,9 @@ int ocfs2_xattr_set(struct inode *inode,
 		.not_found = -ENODATA,
 	};
 
+	if (!ocfs2_supports_xattr(OCFS2_SB(inode->i_sb)))
+		return -EOPNOTSUPP;
+
 	ret = ocfs2_inode_lock(inode, &di_bh, 1);
 	if (ret < 0) {
 		mlog_errno(ret);