From: Milan Broz <mbroz@redhat.com>
Date: Sat, 16 Aug 2008 01:52:00 +0200
Subject: [md] dm crypt: use cond_resched
Message-id: 48A616A0.90406@redhat.com
O-Subject: [RHEL 5.3 PATCH] dm crypt: use cond_resched (#459095)
Bugzilla: 459095
RH-Acked-by: Anton Arapov <aarapov@redhat.com>
RH-Acked-by: John Feeney <jfeeney@redhat.com>
RH-Acked-by: Alasdair G Kergon <agk@redhat.com>

RHEL5.3 dm crypt: use cond_resched
Resolves: rhbz#459095
Patch is upstream, commit c7f1b2044191a82e7f0a1a674751ed582289e2e0

Add cond_resched() to prevent monopolising CPU when processing large bios.

dm-crypt processes encryption of bios in sector units.  If the bio request
is big it can spend a long time in the encryption call.

This helps for example on encrypted laptops to not stuck for long time when
processing large writes.

Kernel with patch compiled and tested.

diff --git a/drivers/md/dm-crypt.c b/drivers/md/dm-crypt.c
index 0c7f22e..d5ce9ce 100644
--- a/drivers/md/dm-crypt.c
+++ b/drivers/md/dm-crypt.c
@@ -305,6 +305,7 @@ static int crypt_convert(struct crypt_config *cc,
 			break;
 
 		ctx->sector++;
+		cond_resched();
 	}
 
 	return r;