[Btrfs-devel] [Btrfs][PATCH]Add readonly inode flag

Yan Zheng yanzheng at 21cn.com
Mon Jan 14 02:18:41 PST 2008


Hello,

This patch adds readonly inode flag support.  A file with this flag
can't be modified, but can be deleted.

Regards
YZ
---
diff -r 067ba546ac2c ctree.h
--- a/ctree.h	Wed Jan 09 15:55:33 2008 -0500
+++ b/ctree.h	Mon Jan 14 14:25:01 2008 +0800
@@ -451,8 +451,9 @@ struct btrfs_root {
 /*
  * Inode flags
  */
-#define BTRFS_INODE_NODATASUM 		0x1
-#define BTRFS_INODE_NODATACOW 		0x2
+#define BTRFS_INODE_NODATASUM 		(1 << 0)
+#define BTRFS_INODE_NODATACOW 		(1 << 1)
+#define BTRFS_INODE_READONLY		(1 << 2)

 #define btrfs_clear_flag(inode, flag)	(BTRFS_I(inode)->flags &= \
 					 ~BTRFS_INODE_##flag)
diff -r 067ba546ac2c inode.c
--- a/inode.c	Wed Jan 09 15:55:33 2008 -0500
+++ b/inode.c	Mon Jan 14 14:25:01 2008 +0800
@@ -2851,6 +2851,14 @@ out_fail:
 	return err;
 }

+static int btrfs_permission(struct inode *inode, int mask,
+			    struct nameidata *nd)
+{
+	if (btrfs_test_flag(inode, READONLY) && (mask & MAY_WRITE))
+		return -EACCES;
+	return generic_permission(inode, mask, NULL);
+}
+
 static struct inode_operations btrfs_dir_inode_operations = {
 	.lookup		= btrfs_lookup,
 	.create		= btrfs_create,
@@ -2866,10 +2874,12 @@ static struct inode_operations btrfs_dir
 	.getxattr	= generic_getxattr,
 	.listxattr	= btrfs_listxattr,
 	.removexattr	= generic_removexattr,
+	.permission	= btrfs_permission,
 };

 static struct inode_operations btrfs_dir_ro_inode_operations = {
 	.lookup		= btrfs_lookup,
+	.permission	= btrfs_permission,
 };

 static struct file_operations btrfs_dir_file_operations = {
@@ -2916,15 +2926,18 @@ static struct inode_operations btrfs_fil
 	.getxattr	= generic_getxattr,
 	.listxattr      = btrfs_listxattr,
 	.removexattr	= generic_removexattr,
+	.permission	= btrfs_permission,
 };

 static struct inode_operations btrfs_special_inode_operations = {
 	.getattr	= btrfs_getattr,
 	.setattr	= btrfs_setattr,
+	.permission	= btrfs_permission,
 };

 static struct inode_operations btrfs_symlink_inode_operations = {
 	.readlink	= generic_readlink,
 	.follow_link	= page_follow_link_light,
 	.put_link	= page_put_link,
+	.permission	= btrfs_permission,
 };



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