[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, 168 insertions, 0 deletions

diff --git a/fs/jffs2/scan.c b/fs/jffs2/scan.c
index cf55b221fc2..f09689e320f 100644
--- a/fs/jffs2/scan.c
+++ b/fs/jffs2/scan.c
@@ -306,6 +306,136 @@ int jffs2_scan_classify_jeb(struct jffs2_sb_info *c, struct jffs2_eraseblock *je
 		return BLK_STATE_ALLDIRTY;
 }
 
+#ifdef CONFIG_JFFS2_FS_XATTR
+static int jffs2_scan_xattr_node(struct jffs2_sb_info *c, struct jffs2_eraseblock *jeb,
+				 struct jffs2_raw_xattr *rx, uint32_t ofs,
+				 struct jffs2_summary *s)
+{
+	struct jffs2_xattr_datum *xd;
+	struct jffs2_raw_node_ref *raw;
+	uint32_t totlen, crc;
+
+	crc = crc32(0, rx, sizeof(struct jffs2_raw_xattr) - 4);
+	if (crc != je32_to_cpu(rx->node_crc)) {
+		if (je32_to_cpu(rx->node_crc) != 0xffffffff)
+			JFFS2_WARNING("node CRC failed at %#08x, read=%#08x, calc=%#08x\n",
+				      ofs, je32_to_cpu(rx->node_crc), crc);
+		DIRTY_SPACE(je32_to_cpu(rx->totlen));
+		return 0;
+	}
+
+	totlen = PAD(sizeof(*rx) + rx->name_len + 1 + je16_to_cpu(rx->value_len));
+	if (totlen != je32_to_cpu(rx->totlen)) {
+		JFFS2_WARNING("node length mismatch at %#08x, read=%u, calc=%u\n",
+			      ofs, je32_to_cpu(rx->totlen), totlen);
+		DIRTY_SPACE(je32_to_cpu(rx->totlen));
+		return 0;
+	}
+
+	raw =  jffs2_alloc_raw_node_ref();
+	if (!raw)
+		return -ENOMEM;
+
+	xd = jffs2_setup_xattr_datum(c, je32_to_cpu(rx->xid), je32_to_cpu(rx->version));
+	if (IS_ERR(xd)) {
+		jffs2_free_raw_node_ref(raw);
+		if (PTR_ERR(xd) == -EEXIST) {
+			DIRTY_SPACE(PAD(je32_to_cpu(rx->totlen)));
+			return 0;
+		}
+		return PTR_ERR(xd);
+	}
+	xd->xprefix = rx->xprefix;
+	xd->name_len = rx->name_len;
+	xd->value_len = je16_to_cpu(rx->value_len);
+	xd->data_crc = je32_to_cpu(rx->data_crc);
+	xd->node = raw;
+
+	raw->__totlen = totlen;
+	raw->flash_offset = ofs | REF_PRISTINE;
+	raw->next_phys = NULL;
+	raw->next_in_ino = (void *)xd;
+	if (!jeb->first_node)
+		jeb->first_node = raw;
+	if (jeb->last_node)
+		jeb->last_node->next_phys = raw;
+	jeb->last_node = raw;
+
+	USED_SPACE(PAD(je32_to_cpu(rx->totlen)));
+	if (jffs2_sum_active())
+		jffs2_sum_add_xattr_mem(s, rx, ofs - jeb->offset);
+	dbg_xattr("scaning xdatum at %#08x (xid=%u, version=%u)\n",
+		  ofs, xd->xid, xd->version);
+	return 0;
+}
+
+static int jffs2_scan_xref_node(struct jffs2_sb_info *c, struct jffs2_eraseblock *jeb,
+				struct jffs2_raw_xref *rr, uint32_t ofs,
+				struct jffs2_summary *s)
+{
+	struct jffs2_xattr_ref *ref;
+	struct jffs2_raw_node_ref *raw;
+	uint32_t crc;
+
+	crc = crc32(0, rr, sizeof(*rr) - 4);
+	if (crc != je32_to_cpu(rr->node_crc)) {
+		if (je32_to_cpu(rr->node_crc) != 0xffffffff)
+			JFFS2_WARNING("node CRC failed at %#08x, read=%#08x, calc=%#08x\n",
+				      ofs, je32_to_cpu(rr->node_crc), crc);
+		DIRTY_SPACE(PAD(je32_to_cpu(rr->totlen)));
+		return 0;
+	}
+
+	if (PAD(sizeof(struct jffs2_raw_xref)) != je32_to_cpu(rr->totlen)) {
+		JFFS2_WARNING("node length mismatch at %#08x, read=%u, calc=%u\n",
+			      ofs, je32_to_cpu(rr->totlen),
+			      PAD(sizeof(struct jffs2_raw_xref)));
+		DIRTY_SPACE(je32_to_cpu(rr->totlen));
+		return 0;
+	}
+
+	ref = jffs2_alloc_xattr_ref();
+	if (!ref)
+		return -ENOMEM;
+
+	raw =  jffs2_alloc_raw_node_ref();
+	if (!raw) {
+		jffs2_free_xattr_ref(ref);
+		return -ENOMEM;
+	}
+
+	/* BEFORE jffs2_build_xattr_subsystem() called, 
+	 * ref->xid is used to store 32bit xid, xd is not used
+	 * ref->ino is used to store 32bit inode-number, ic is not used
+	 * Thoes variables are declared as union, thus using those
+	 * are exclusive. In a similar way, ref->ilist is temporarily
+	 * used to chain all xattr_ref object. It's re-chained to
+	 * jffs2_inode_cache in jffs2_build_xattr_subsystem() correctly.
+	 */
+	ref->node = raw;
+	ref->ino = je32_to_cpu(rr->ino);
+	ref->xid = je32_to_cpu(rr->xid);
+	list_add_tail(&ref->ilist, &c->xattr_temp);
+
+	raw->__totlen = PAD(je32_to_cpu(rr->totlen));
+	raw->flash_offset = ofs | REF_PRISTINE;
+	raw->next_phys = NULL;
+	raw->next_in_ino = (void *)ref;
+	if (!jeb->first_node)
+		jeb->first_node = raw;
+	if (jeb->last_node)
+		jeb->last_node->next_phys = raw;
+	jeb->last_node = raw;
+
+	USED_SPACE(PAD(je32_to_cpu(rr->totlen)));	
+	if (jffs2_sum_active())
+		jffs2_sum_add_xref_mem(s, rr, ofs - jeb->offset);
+	dbg_xattr("scan xref at %#08x (xid=%u, ino=%u)\n",
+		  ofs, ref->xid, ref->ino);
+	return 0;
+}
+#endif
+
 static int jffs2_scan_eraseblock (struct jffs2_sb_info *c, struct jffs2_eraseblock *jeb,
 				unsigned char *buf, uint32_t buf_size, struct jffs2_summary *s) {
 	struct jffs2_unknown_node *node;
@@ -614,6 +744,43 @@ scan_more:
 			ofs += PAD(je32_to_cpu(node->totlen));
 			break;
 
+#ifdef CONFIG_JFFS2_FS_XATTR
+		case JFFS2_NODETYPE_XATTR:
+			if (buf_ofs + buf_len < ofs + je32_to_cpu(node->totlen)) {
+				buf_len = min_t(uint32_t, buf_size, jeb->offset + c->sector_size - ofs);
+				D1(printk(KERN_DEBUG "Fewer than %d bytes (xattr node)"
+					  " left to end of buf. Reading 0x%x at 0x%08x\n",
+					  je32_to_cpu(node->totlen), buf_len, ofs));
+				err = jffs2_fill_scan_buf(c, buf, ofs, buf_len);
+				if (err)
+					return err;
+				buf_ofs = ofs;
+				node = (void *)buf;
+			}
+			err = jffs2_scan_xattr_node(c, jeb, (void *)node, ofs, s);
+			if (err)
+				return err;
+			ofs += PAD(je32_to_cpu(node->totlen));
+			break;
+		case JFFS2_NODETYPE_XREF:
+			if (buf_ofs + buf_len < ofs + je32_to_cpu(node->totlen)) {
+				buf_len = min_t(uint32_t, buf_size, jeb->offset + c->sector_size - ofs);
+				D1(printk(KERN_DEBUG "Fewer than %d bytes (xref node)"
+					  " left to end of buf. Reading 0x%x at 0x%08x\n",
+					  je32_to_cpu(node->totlen), buf_len, ofs));
+				err = jffs2_fill_scan_buf(c, buf, ofs, buf_len);
+				if (err)
+					return err;
+				buf_ofs = ofs;
+				node = (void *)buf;
+			}
+			err = jffs2_scan_xref_node(c, jeb, (void *)node, ofs, s);
+			if (err)
+				return err;
+			ofs += PAD(je32_to_cpu(node->totlen));
+			break;
+#endif	/* CONFIG_JFFS2_FS_XATTR */
+
 		case JFFS2_NODETYPE_CLEANMARKER:
 			D1(printk(KERN_DEBUG "CLEANMARKER node found at 0x%08x\n", ofs));
 			if (je32_to_cpu(node->totlen) != c->cleanmarker_size) {
@@ -721,6 +888,7 @@ struct jffs2_inode_cache *jffs2_scan_make_ino_cache(struct jffs2_sb_info *c, uin
 
 	ic->ino = ino;
 	ic->nodes = (void *)ic;
+	init_xattr_inode_cache(ic);
 	jffs2_add_ino_cache(c, ic);
 	if (ino == 1)
 		ic->nlink = 1;