From: "Aneesh Kumar K.V" Subject: [PATCH] mm: Add range_cont mode for writeback. Date: Fri, 6 Jun 2008 23:54:51 +0530 Message-ID: <1212776693-435-6-git-send-email-aneesh.kumar@linux.vnet.ibm.com> References: <1212776693-435-1-git-send-email-aneesh.kumar@linux.vnet.ibm.com> <1212776693-435-2-git-send-email-aneesh.kumar@linux.vnet.ibm.com> <1212776693-435-3-git-send-email-aneesh.kumar@linux.vnet.ibm.com> <1212776693-435-4-git-send-email-aneesh.kumar@linux.vnet.ibm.com> <1212776693-435-5-git-send-email-aneesh.kumar@linux.vnet.ibm.com> Cc: linux-ext4@vger.kernel.org, "Aneesh Kumar K.V" To: cmm@us.ibm.com, tytso@mit.edu, sandeen@redhat.com Return-path: Received: from E23SMTP06.au.ibm.com ([202.81.18.175]:38926 "EHLO e23smtp06.au.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755383AbYFFSZg (ORCPT ); Fri, 6 Jun 2008 14:25:36 -0400 Received: from sd0109e.au.ibm.com (d23rh905.au.ibm.com [202.81.18.225]) by e23smtp06.au.ibm.com (8.13.1/8.13.1) with ESMTP id m56IP455024798 for ; Sat, 7 Jun 2008 04:25:04 +1000 Received: from d23av03.au.ibm.com (d23av03.au.ibm.com [9.190.234.97]) by sd0109e.au.ibm.com (8.13.8/8.13.8/NCO v8.7) with ESMTP id m56ITjG0290096 for ; Sat, 7 Jun 2008 04:29:45 +1000 Received: from d23av03.au.ibm.com (loopback [127.0.0.1]) by d23av03.au.ibm.com (8.12.11.20060308/8.13.3) with ESMTP id m56IPXeh031800 for ; Sat, 7 Jun 2008 04:25:34 +1000 In-Reply-To: <1212776693-435-5-git-send-email-aneesh.kumar@linux.vnet.ibm.com> Sender: linux-ext4-owner@vger.kernel.org List-ID: Filesystems like ext4 needs to start a new transaction in the writepages for block allocation. This happens with delayed allocation and there is limit to how many credits we can request from the journal layer. So we call write_cache_pages multiple times with wbc->nr_to_write set to the maximum possible value limitted by the max journal credits available. Add a new mode to writeback that enables us to handle this behaviour. In the new mode we update the wbc->range_start to point to the new offset to be written. Next call to call to write_cache_pages will start writeout from specified range_start offset. In the new mode we also limit writing to the specified wbc->range_end. Signed-off-by: Aneesh Kumar K.V --- include/linux/writeback.h | 1 + mm/page-writeback.c | 13 +++++++++++++ 2 files changed, 14 insertions(+), 0 deletions(-) diff --git a/include/linux/writeback.h b/include/linux/writeback.h index f462439..0d8573e 100644 --- a/include/linux/writeback.h +++ b/include/linux/writeback.h @@ -63,6 +63,7 @@ struct writeback_control { unsigned for_writepages:1; /* This is a writepages() call */ unsigned range_cyclic:1; /* range_start is cyclic */ unsigned more_io:1; /* more io to be dispatched */ + unsigned range_cont:1; }; /* diff --git a/mm/page-writeback.c b/mm/page-writeback.c index 789b6ad..7306902 100644 --- a/mm/page-writeback.c +++ b/mm/page-writeback.c @@ -882,6 +882,16 @@ int write_cache_pages(struct address_space *mapping, if (wbc->range_cyclic) { index = mapping->writeback_index; /* Start from prev offset */ end = -1; + } else if (wbc->range_cont) { + index = wbc->range_start >> PAGE_CACHE_SHIFT; + end = wbc->range_end >> PAGE_CACHE_SHIFT; + /* + * we want to set the writeback_index when congested + * and we are requesting for nonblocking mode, + * because we won't force the range_cont mode then + */ + if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX) + range_whole = 1; } else { index = wbc->range_start >> PAGE_CACHE_SHIFT; end = wbc->range_end >> PAGE_CACHE_SHIFT; @@ -956,6 +966,9 @@ int write_cache_pages(struct address_space *mapping, } if (wbc->range_cyclic || (range_whole && wbc->nr_to_write > 0)) mapping->writeback_index = index; + + if (wbc->range_cont) + wbc->range_start = index << PAGE_CACHE_SHIFT; return ret; } EXPORT_SYMBOL(write_cache_pages); -- 1.5.5.1.357.g1af8b.dirty