[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>

1 files changed, 40 insertions, 0 deletions

diff --git a/include/linux/jffs2.h b/include/linux/jffs2.h
index cf792bb3c726..2cac60e55322 100644
--- a/include/linux/jffs2.h
+++ b/include/linux/jffs2.h
@@ -65,6 +65,18 @@
 
 #define JFFS2_NODETYPE_SUMMARY (JFFS2_FEATURE_RWCOMPAT_DELETE | JFFS2_NODE_ACCURATE | 6)
 
+#define JFFS2_NODETYPE_XATTR (JFFS2_FEATURE_INCOMPAT | JFFS2_NODE_ACCURATE | 8)
+#define JFFS2_NODETYPE_XREF (JFFS2_FEATURE_INCOMPAT | JFFS2_NODE_ACCURATE | 9)
+
+/* XATTR Related */
+#define JFFS2_XPREFIX_USER              1       /* for "user." */
+#define JFFS2_XPREFIX_SECURITY          2       /* for "security." */
+#define JFFS2_XPREFIX_ACL_ACCESS        3       /* for "system.posix_acl_access" */
+#define JFFS2_XPREFIX_ACL_DEFAULT       4       /* for "system.posix_acl_default" */
+#define JFFS2_XPREFIX_TRUSTED           5       /* for "trusted.*" */
+
+#define JFFS2_ACL_VERSION               0x0001
+
 // Maybe later...
 //#define JFFS2_NODETYPE_CHECKPOINT (JFFS2_FEATURE_RWCOMPAT_DELETE | JFFS2_NODE_ACCURATE | 3)
 //#define JFFS2_NODETYPE_OPTIONS (JFFS2_FEATURE_RWCOMPAT_COPY | JFFS2_NODE_ACCURATE | 4)
@@ -151,6 +163,32 @@ struct jffs2_raw_inode
         uint8_t data[0];
 } __attribute__((packed));
 
+struct jffs2_raw_xattr {
+        jint16_t magic;
+        jint16_t nodetype;      /* = JFFS2_NODETYPE_XATTR */
+        jint32_t totlen;
+        jint32_t hdr_crc;
+        jint32_t xid;           /* XATTR identifier number */
+        jint32_t version;
+        uint8_t xprefix;
+        uint8_t name_len;
+        jint16_t value_len;
+        jint32_t data_crc;
+        jint32_t node_crc;
+        uint8_t data[0];
+} __attribute__((packed));
+
+struct jffs2_raw_xref
+{
+        jint16_t magic;
+        jint16_t nodetype;      /* = JFFS2_NODETYPE_XREF */
+        jint32_t totlen;
+        jint32_t hdr_crc;
+        jint32_t ino;           /* inode number */
+        jint32_t xid;           /* XATTR identifier number */
+        jint32_t node_crc;
+} __attribute__((packed));
+
 struct jffs2_raw_summary
 {
         jint16_t magic;
@@ -169,6 +207,8 @@ union jffs2_node_union
 {
         struct jffs2_raw_inode i;
         struct jffs2_raw_dirent d;
+        struct jffs2_raw_xattr x;
+        struct jffs2_raw_xref r;
         struct jffs2_raw_summary s;
         struct jffs2_unknown_node u;
 };