Subject: [PATCH] Support for "gnu" extended attributes namespace for ext4

This support is needed for GNU Hurd, for things like active translators.
---
fs/ext4/Makefile | 3 +-
fs/ext4/xattr.c | 2 +
fs/ext4/xattr.h | 2 +
fs/ext4/xattr_gnu.c | 62 +++++++++++++++++++++++++++++++++++++++++++++++++++
4 files changed, 68 insertions(+), 1 deletions(-)
create mode 100644 fs/ext4/xattr_gnu.c

diff --git a/fs/ext4/Makefile b/fs/ext4/Makefile
index ac6fa8c..b148ba8 100644
--- a/fs/ext4/Makefile
+++ b/fs/ext4/Makefile
@@ -8,6 +8,7 @@ ext4dev-y := balloc.o bitmap.o dir.o file.o fsync.o ialloc.o inode.o \
ioctl.o namei.o super.o symlink.o hash.o resize.o extents.o \
ext4_jbd2.o migrate.o mballoc.o

-ext4dev-$(CONFIG_EXT4DEV_FS_XATTR) += xattr.o xattr_user.o xattr_trusted.o
+ext4dev-$(CONFIG_EXT4DEV_FS_XATTR) += xattr.o xattr_user.o \
+ xattr_trusted.o xattr_gnu.o
ext4dev-$(CONFIG_EXT4DEV_FS_POSIX_ACL) += acl.o
ext4dev-$(CONFIG_EXT4DEV_FS_SECURITY) += xattr_security.o
diff --git a/fs/ext4/xattr.c b/fs/ext4/xattr.c
index ff08633..6c47327 100644
--- a/fs/ext4/xattr.c
+++ b/fs/ext4/xattr.c
@@ -107,6 +107,7 @@ static struct xattr_handler *ext4_xattr_handler_map[] = {
#ifdef CONFIG_EXT4DEV_FS_SECURITY
[EXT4_XATTR_INDEX_SECURITY] = &ext4_xattr_security_handler,
#endif
+ [EXT4_XATTR_INDEX_GNU] = &ext4_xattr_gnu_handler,
};

struct xattr_handler *ext4_xattr_handlers[] = {
@@ -119,6 +120,7 @@ struct xattr_handler *ext4_xattr_handlers[] = {
#ifdef CONFIG_EXT4DEV_FS_SECURITY
&ext4_xattr_security_handler,
#endif
+ &ext4_xattr_gnu_handler,
NULL
};

diff --git a/fs/ext4/xattr.h b/fs/ext4/xattr.h
index 5992fe9..bb481b4 100644
--- a/fs/ext4/xattr.h
+++ b/fs/ext4/xattr.h
@@ -21,6 +21,7 @@
#define EXT4_XATTR_INDEX_TRUSTED 4
#define EXT4_XATTR_INDEX_LUSTRE 5
#define EXT4_XATTR_INDEX_SECURITY 6
+#define EXT4_XATTR_INDEX_GNU 7

struct ext4_xattr_header {
__le32 h_magic; /* magic number for identification */
@@ -70,6 +71,7 @@ extern struct xattr_handler ext4_xattr_trusted_handler;
extern struct xattr_handler ext4_xattr_acl_access_handler;
extern struct xattr_handler ext4_xattr_acl_default_handler;
extern struct xattr_handler ext4_xattr_security_handler;
+extern struct xattr_handler ext4_xattr_gnu_handler;

extern ssize_t ext4_listxattr(struct dentry *, char *, size_t);

diff --git a/fs/ext4/xattr_gnu.c b/fs/ext4/xattr_gnu.c
new file mode 100644
index 0000000..039f839
--- /dev/null
+++ b/fs/ext4/xattr_gnu.c
@@ -0,0 +1,62 @@
+/*
+ * linux/fs/ext4/xattr_gnu.c
+ * Handler for gnu extended attributes.
+ *
+ * Copyright (C) 2003 by Andreas Gruenbacher, <[email protected]>
+ * Copyright Thadeu Lima de Souza Cascardo <[email protected]>
+ */
+
+#include <linux/module.h>
+#include <linux/string.h>
+#include <linux/capability.h>
+#include <linux/fs.h>
+#include <linux/ext4_jbd2.h>
+#include <linux/ext4_fs.h>
+#include "xattr.h"
+
+#define XATTR_GNU_PREFIX "gnu."
+
+static size_t
+ext4_xattr_gnu_list(struct inode *inode, char *list, size_t list_size,
+ const char *name, size_t name_len)
+{
+ const size_t prefix_len = sizeof(XATTR_GNU_PREFIX)-1;
+ const size_t total_len = prefix_len + name_len + 1;
+
+ if (!capable(CAP_SYS_ADMIN))
+ return 0;
+
+ if (list && total_len <= list_size) {
+ memcpy(list, XATTR_GNU_PREFIX, prefix_len);
+ memcpy(list+prefix_len, name, name_len);
+ list[prefix_len + name_len] = '\0';
+ }
+ return total_len;
+}
+
+static int
+ext4_xattr_gnu_get(struct inode *inode, const char *name,
+ void *buffer, size_t size)
+{
+ if (strcmp(name, "") == 0)
+ return -EINVAL;
+ return ext4_xattr_get(inode, EXT4_XATTR_INDEX_GNU, name,
+ buffer, size);
+}
+
+static int
+ext4_xattr_gnu_set(struct inode *inode, const char *name,
+ const void *value, size_t size, int flags)
+{
+ if (strcmp(name, "") == 0)
+ return -EINVAL;
+ return ext4_xattr_set(inode, EXT4_XATTR_INDEX_GNU, name,
+ value, size, flags);
+}
+
+struct xattr_handler ext4_xattr_gnu_handler = {
+ .prefix = XATTR_GNU_PREFIX,
+ .list = ext4_xattr_gnu_list,
+ .get = ext4_xattr_gnu_get,
+ .set = ext4_xattr_gnu_set,
+};
--
1.5.5.4