btrfs: refactor btrfs_set_props to validate externally

In preparation to merge multiple transactions when setting the
compression flags, split btrfs_set_props() validation part outside of
it.
Signed-off-by: Anand Jain <anand.jain@oracle.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/ioctl.c

@@ -284,6 +284,7 @@ static int btrfs_ioctl_setflags(struct file *file, void __user *arg)
 		binode->flags &= ~BTRFS_INODE_COMPRESS;
 		binode->flags |= BTRFS_INODE_NOCOMPRESS;
 
+		/* set no-compression no need to validate prop here */
 		ret = btrfs_set_prop_trans(inode, "btrfs.compression", NULL,
 					   0, 0);
 		if (ret && ret != -ENODATA)
@@ -299,6 +300,7 @@ static int btrfs_ioctl_setflags(struct file *file, void __user *arg)
 		binode->flags |= BTRFS_INODE_COMPRESS;
 		binode->flags &= ~BTRFS_INODE_NOCOMPRESS;
 
+		/* compress_type is already validated during mount options */
 		comp = btrfs_compress_type2str(fs_info->compress_type);
 		if (!comp || comp[0] == 0)
 			comp = btrfs_compress_type2str(BTRFS_COMPRESS_ZLIB);
@@ -309,6 +311,7 @@ static int btrfs_ioctl_setflags(struct file *file, void __user *arg)
 			goto out_drop;
 
 	} else {
+		/* reset prop, no need of validate prop here */
 		ret = btrfs_set_prop_trans(inode, "btrfs.compression", NULL,
 					   0, 0);
 		if (ret && ret != -ENODATA)

fs/btrfs/props.c

@@ -55,6 +55,23 @@ find_prop_handler(const char *name,
 	return NULL;
 }
 
+int btrfs_validate_prop(const char *name, const char *value, size_t value_len)
+{
+	const struct prop_handler *handler;
+
+	if (strlen(name) <= XATTR_BTRFS_PREFIX_LEN)
+		return -EINVAL;
+
+	handler = find_prop_handler(name, NULL);
+	if (!handler)
+		return -EINVAL;
+
+	if (value_len == 0)
+		return 0;
+
+	return handler->validate(value, value_len);
+}
+
 static int btrfs_set_prop(struct btrfs_trans_handle *trans, struct inode *inode,
 			  const char *name, const char *value, size_t value_len,
 			  int flags)
@@ -62,9 +79,6 @@ static int btrfs_set_prop(struct btrfs_trans_handle *trans, struct inode *inode,
 	const struct prop_handler *handler;
 	int ret;
 
-	if (strlen(name) <= XATTR_BTRFS_PREFIX_LEN)
-		return -EINVAL;
-
 	handler = find_prop_handler(name, NULL);
 	if (!handler)
 		return -EINVAL;
@@ -85,9 +99,6 @@ static int btrfs_set_prop(struct btrfs_trans_handle *trans, struct inode *inode,
 		return ret;
 	}
 
-	ret = handler->validate(value, value_len);
-	if (ret)
-		return ret;
 	if (trans)
 		ret = btrfs_setxattr(trans, inode, handler->xattr_name, value,
 				     value_len, flags);

fs/btrfs/props.h

@@ -12,6 +12,7 @@ void __init btrfs_props_init(void);
 
 int btrfs_set_prop_trans(struct inode *inode, const char *name,
 			 const char *value, size_t value_len, int flags);
+int btrfs_validate_prop(const char *name, const char *value, size_t value_len);
 
 int btrfs_load_inode_props(struct inode *inode, struct btrfs_path *path);
 

fs/btrfs/xattr.c

@@ -371,7 +371,12 @@ static int btrfs_xattr_handler_set_prop(const struct xattr_handler *handler,
 					const char *name, const void *value,
 					size_t size, int flags)
 {
+	int ret;
+
 	name = xattr_full_name(handler, name);
+	ret = btrfs_validate_prop(name, value, size);
+	if (ret)
+		return ret;
 	return btrfs_set_prop_trans(inode, name, value, size, flags);
 }