xfs: refactor name/length checks in xfs_attri_validate

Move the name and length checks into the attr op switch statement so
that we can perform more specific checks of the value length.  Over the
next few patches we're going to add new attr op flags with different
validation requirements.

While we're at it, remove the incorrect comment.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>

fs/xfs/xfs_attr_item.c

@@ -466,6 +466,12 @@ xfs_attri_item_match(
 	return ATTRI_ITEM(lip)->attri_format.alfi_id == intent_id;
 }
 
+static inline bool
+xfs_attri_validate_namelen(unsigned int namelen)
+{
+	return namelen > 0 && namelen <= XATTR_NAME_MAX;
+}
+
 /* Is this recovered ATTRI format ok? */
 static inline bool
 xfs_attri_validate(
@@ -486,23 +492,24 @@ xfs_attri_validate(
 	if (attrp->alfi_attr_filter & ~XFS_ATTRI_FILTER_MASK)
 		return false;
 
-	/* alfi_op_flags should be either a set or remove */
 	switch (op) {
 	case XFS_ATTRI_OP_FLAGS_SET:
 	case XFS_ATTRI_OP_FLAGS_REPLACE:
+		if (attrp->alfi_value_len > XATTR_SIZE_MAX)
+			return false;
+		if (!xfs_attri_validate_namelen(attrp->alfi_name_len))
+			return false;
+		break;
 	case XFS_ATTRI_OP_FLAGS_REMOVE:
+		if (attrp->alfi_value_len != 0)
+			return false;
+		if (!xfs_attri_validate_namelen(attrp->alfi_name_len))
+			return false;
 		break;
 	default:
 		return false;
 	}
 
-	if (attrp->alfi_value_len > XATTR_SIZE_MAX)
-		return false;
-
-	if ((attrp->alfi_name_len > XATTR_NAME_MAX) ||
-	    (attrp->alfi_name_len == 0))
-		return false;
-
 	return xfs_verify_ino(mp, attrp->alfi_ino);
 }