[JFFS2][XATTR] XATTR support on JFFS2 (version. 5)

This attached patches provide xattr support including POSIX-ACL and
SELinux support on JFFS2 (version.5).

There are some significant differences from previous version posted
at last December.
The biggest change is addition of EBS(Erase Block Summary) support.
Currently, both kernel and usermode utility (sumtool) can recognize
xattr nodes which have JFFS2_NODETYPE_XATTR/_XREF nodetype.

In addition, some bugs are fixed.
- A potential race condition was fixed.
- Unexpected fail when updating a xattr by same name/value pair was fixed.
- A bug when removing xattr name/value pair was fixed.

The fundamental structures (such as using two new nodetypes and exclusion
mechanism by rwsem) are unchanged. But most of implementation were reviewed
and updated if necessary.
Espacially, we had to change several internal implementations related to
load_xattr_datum() to avoid a potential race condition.

[1/2] xattr_on_jffs2.kernel.version-5.patch
[2/2] xattr_on_jffs2.utils.version-5.patch

Signed-off-by: KaiGai Kohei <kaigai@ak.jp.nec.com>
Signed-off-by: David Woodhouse <dwmw2@infradead.org>

fs/Kconfig

@@ -1075,6 +1075,44 @@ config JFFS2_FS_DEBUG
 	  If reporting bugs, please try to have available a full dump of the
 	  messages at debug level 1 while the misbehaviour was occurring.
 
+config JFFS2_FS_XATTR
+	bool "JFFS2 XATTR support"
+	depends on JFFS2_FS
+	default n
+	help
+	  Extended attributes are name:value pairs associated with inodes by
+	  the kernel or by users (see the attr(5) manual page, or visit
+	  <http://acl.bestbits.at/> for details).
+
+	  If unsure, say N.
+
+config JFFS2_FS_POSIX_ACL
+	bool "JFFS2 POSIX Access Control Lists"
+	depends on JFFS2_FS_XATTR
+	default y
+	select FS_POSIX_ACL
+	help
+	  Posix Access Control Lists (ACLs) support permissions for users and
+	  groups beyond the owner/group/world scheme.
+
+	  To learn more about Access Control Lists, visit the Posix ACLs for
+	  Linux website <http://acl.bestbits.at/>.
+
+	  If you don't know what Access Control Lists are, say N
+
+config JFFS2_FS_SECURITY
+	bool "JFFS2 Security Labels"
+	depends on JFFS2_FS_XATTR
+	default y
+	help
+	  Security labels support alternative access control models
+	  implemented by security modules like SELinux.  This option
+	  enables an extended attribute handler for file security
+	  labels in the jffs2 filesystem.
+
+	  If you are not using a security module that requires using
+	  extended attributes for file security labels, say N.
+
 config JFFS2_FS_WRITEBUFFER
 	bool "JFFS2 write-buffering support"
 	depends on JFFS2_FS

fs/jffs2/Makefile

@@ -12,6 +12,9 @@ jffs2-y	+= symlink.o build.o erase.o background.o fs.o writev.o
 jffs2-y	+= super.o debug.o
 
 jffs2-$(CONFIG_JFFS2_FS_WRITEBUFFER)	+= wbuf.o
+jffs2-$(CONFIG_JFFS2_FS_XATTR)		+= xattr.o xattr_trusted.o xattr_user.o
+jffs2-$(CONFIG_JFFS2_FS_SECURITY)	+= security.o
+jffs2-$(CONFIG_JFFS2_FS_POSIX_ACL)	+= acl.o
 jffs2-$(CONFIG_JFFS2_RUBIN)	+= compr_rubin.o
 jffs2-$(CONFIG_JFFS2_RTIME)	+= compr_rtime.o
 jffs2-$(CONFIG_JFFS2_ZLIB)	+= compr_zlib.o