[JFFS2] Better fix for all-zero node headers

No need to check for all-zero header since the header cannot
be zero due to other checks.

Replace the all-zero header check in readinode.c with a
check for the magic word.

Signed-off-by: Joakim Tjernlund <[e-mail]>
Signed-off-by: David Woodhouse <[e-mail]>

fs/jffs2/readinode.c

···
 			jffs2_mark_node_obsolete(c, ref);
 			goto cont;
 		}
-		/* Due to poor choice of crc32 seed, an all-zero node will have a correct CRC */
-		if (!je32_to_cpu(node->u.hdr_crc) && !je16_to_cpu(node->u.nodetype) &&
-		    !je16_to_cpu(node->u.magic) && !je32_to_cpu(node->u.totlen)) {
-			JFFS2_NOTICE("All zero node header at %#08x.\n", ref_offset(ref));
+		if (je16_to_cpu(node->u.magic) != JFFS2_MAGIC_BITMASK) {
+			/* Not a JFFS2 node, whinge and move on */
+			JFFS2_NOTICE("Wrong magic bitmask 0x%04x in node header at %#08x.\n",
+				     je16_to_cpu(node->u.magic), ref_offset(ref));
 			jffs2_mark_node_obsolete(c, ref);
 			goto cont;
 		}

fs/jffs2/scan.c

···
 			ofs += 4;
 			continue;
 		}
-		/* Due to poor choice of crc32 seed, an all-zero node will have a correct CRC */
-		if (!je32_to_cpu(node->hdr_crc) && !je16_to_cpu(node->nodetype) &&
-		    !je16_to_cpu(node->magic) && !je32_to_cpu(node->totlen)) {
-			noisy_printk(&noise, "jffs2_scan_eraseblock(): All zero node header at 0x%08x.\n", ofs);
-			if ((err = jffs2_scan_dirty_space(c, jeb, 4)))
-				return err;
-			ofs += 4;
-			continue;
-		}
 
-		if (ofs + je32_to_cpu(node->totlen) >
-		    jeb->offset + c->sector_size) {
+		if (ofs + je32_to_cpu(node->totlen) > jeb->offset + c->sector_size) {
 			/* Eep. Node goes over the end of the erase block. */
 			printk(KERN_WARNING "Node at 0x%08x with length 0x%08x would run over the end of the erase block\n",
 			       ofs, je32_to_cpu(node->totlen));