Fix noop elevator request merging (in current 2.5 bk)

Fix noop elevator request merging (in current 2.5 bk)

[Oleg Drokin]

Hello!

   This patch is required otherwise in case if elv_try_last_merge returns nonzero, we do not
   initialise *req, and subsequent BUG_ON() in __make_request() will dies because req is NULL
   (or is just uninitialised).
   This stopped my UBD devices to work, that's how I noticed ;)

Bye,
    Oleg

# This is a BitKeeper generated patch for the following project:
# Project Name: Linux kernel tree
# This patch format is intended for GNU patch command version 2.5 or higher.
# This patch includes the following deltas:
#	           ChangeSet	1.1228  -> 1.1229 
#	drivers/block/noop-iosched.c	1.2     -> 1.3    
#
# The following is the BitKeeper ChangeSet Log
# --------------------------------------------
# 03/09/08	green@angband.namesys.com	1.1229
# Fix request merging in noop elevator, preventing a crash in __make_request()
# --------------------------------------------
#
diff -Nru a/drivers/block/noop-iosched.c b/drivers/block/noop-iosched.c
--- a/drivers/block/noop-iosched.c	Mon Sep  8 19:25:35 2003
+++ b/drivers/block/noop-iosched.c	Mon Sep  8 19:25:35 2003
@@ -24,8 +24,10 @@
 	struct request *__rq;
 	int ret;
 
-	if ((ret = elv_try_last_merge(q, bio)))
+	if ((ret = elv_try_last_merge(q, bio))) {
+		*req = q->last_merge;
 		return ret;
+	}
 
 	while ((entry = entry->prev) != &q->queue_head) {
 		__rq = list_entry_rq(entry);

Re: Fix noop elevator request merging (in current 2.5 bk)

[Jens Axboe]

On Mon, Sep 08 2003, Oleg Drokin wrote:
> Hello!
> 
>    This patch is required otherwise in case if elv_try_last_merge
>    returns nonzero, we do not initialise *req, and subsequent BUG_ON()
>    in __make_request() will dies because req is NULL (or is just
>    uninitialised).  This stopped my UBD devices to work, that's how I
>    noticed ;)

Thanks, patch looks good.

-- 
Jens Axboe