Handle possible race:
do not proceed uf_readpages_filler if page is already uptodate.
Print debugging info.

Signed-off-by: Edward Shishkin <edward@namesys.com>
---
 linux-2.6.20-mm2/fs/reiser4/plugin/file/file.c            |    4 +++
 linux-2.6.20-mm2/fs/reiser4/plugin/item/extent_file_ops.c |   17 ++++++++++++++
 2 files changed, 21 insertions(+)

--- linux-2.6.20-mm2/fs/reiser4/plugin/file/file.c.orig
+++ linux-2.6.20-mm2/fs/reiser4/plugin/file/file.c
@@ -1619,6 +1619,10 @@
 		lock_page(page);
 		cbk_done = 1;
 	}
+	if (PageUptodate(page)) {
+		unlock_page(page);
+		return 0;
+	}
 	ret = zload(rc->coord.node);
 	if (ret) {
 		unlock_page(page);
--- linux-2.6.20-mm2/fs/reiser4/plugin/item/extent_file_ops.c.orig
+++ linux-2.6.20-mm2/fs/reiser4/plugin/item/extent_file_ops.c
@@ -1157,7 +1157,24 @@
 
 	case UNALLOCATED_EXTENT:
 		j = jfind(mapping, index);
+		if (j == NULL) {
+			dump_stack();
+			printk("edward-2000: oid = %llu\n",
+			       (unsigned long long)oid);
+			printk("edward-2001: Jnode not found\n");
+		}
 		assert("nikita-2688", j);
+		if (jnode_page(j) != NULL) {
+			dump_stack();
+			printk("edward-2002: oid = %llu\n",
+			       (unsigned long long)oid);
+			printk("edward-2003: read page  %p of idx %lu\n",
+			       page, page->index);
+			printk("edward-2004: jnode page %p of idx %lu\n",
+			       jnode_page(j), jnode_page(j)->index);
+			printk("edward-2005: jnode blknr =  %llu\n",
+			       (unsigned long long)(*jnode_get_block(j)));
+		}
 		assert("vs-1426", jnode_page(j) == NULL);
 
 		spin_lock_jnode(j);