btrfs: provide simple rcu-walk ACL implementation

Nick Piggin · Nick Piggin · commit 258a5aa8dfc6 · 2011-01-07T17:50:30.000+11:00
This simple implementation just checks for no ACLs on the inode, and
if so, then the rcu-walk may proceed, otherwise fail it.

Signed-off-by: Nick Piggin &lt;npiggin@kernel.dk&gt;
diff --git a/fs/btrfs/acl.c b/fs/btrfs/acl.c
@@ -187,18 +187,21 @@ static int btrfs_xattr_acl_set(struct dentry *dentry, const char *name,
 
 int btrfs_check_acl(struct inode *inode, int mask, unsigned int flags)
 {
-	struct posix_acl *acl;
 	int error = -EAGAIN;
 
-	if (flags & IPERM_FLAG_RCU)
-		return -ECHILD;
+	if (flags & IPERM_FLAG_RCU) {
+		if (!negative_cached_acl(inode, ACL_TYPE_ACCESS))
+			error = -ECHILD;
 
-	acl = btrfs_get_acl(inode, ACL_TYPE_ACCESS);
-	if (IS_ERR(acl))
-		return PTR_ERR(acl);
-	if (acl) {
-		error = posix_acl_permission(inode, acl, mask);
-		posix_acl_release(acl);
+	} else {
+		struct posix_acl *acl;
+		acl = btrfs_get_acl(inode, ACL_TYPE_ACCESS);
+		if (IS_ERR(acl))
+			return PTR_ERR(acl);
+		if (acl) {
+			error = posix_acl_permission(inode, acl, mask);
+			posix_acl_release(acl);
+		}
 	}
 
 	return error;
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
@@ -7213,9 +7213,6 @@ static int btrfs_set_page_dirty(struct page *page)
 
 static int btrfs_permission(struct inode *inode, int mask, unsigned int flags)
 {
-	if (flags & IPERM_FLAG_RCU)
-		return -ECHILD;
-
 	if ((BTRFS_I(inode)->flags & BTRFS_INODE_READONLY) && (mask & MAY_WRITE))
 		return -EACCES;
 	return generic_permission(inode, mask, flags, btrfs_check_acl);

Original file line number	Diff line number	Diff line change
`@@ -7213,9 +7213,6 @@ static int btrfs_set_page_dirty(struct page *page)`
`7213`	`7213`
`7214`	`7214`	`static int btrfs_permission(struct inode *inode, int mask, unsigned int flags)`
`7215`	`7215`	`{`
`7216`		`- if (flags & IPERM_FLAG_RCU)`
`7217`		`- return -ECHILD;`
`7218`		`-`
`7219`	`7216`	`if ((BTRFS_I(inode)->flags & BTRFS_INODE_READONLY) && (mask & MAY_WRITE))`
`7220`	`7217`	`return -EACCES;`
`7221`	`7218`	`return generic_permission(inode, mask, flags, btrfs_check_acl);`