From patchwork Mon May 24 22:28:08 2010 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: gregkh@suse.de X-Patchwork-Id: 53473 Return-Path: X-Original-To: patchwork-incoming@ozlabs.org Delivered-To: patchwork-incoming@ozlabs.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id F0778B7D7F for ; Tue, 25 May 2010 08:40:55 +1000 (EST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758275Ab0EXWiW (ORCPT ); Mon, 24 May 2010 18:38:22 -0400 Received: from kroah.org ([198.145.64.141]:42355 "EHLO coco.kroah.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755430Ab0EXWiU (ORCPT ); Mon, 24 May 2010 18:38:20 -0400 Received: from localhost (c-24-16-163-131.hsd1.wa.comcast.net [24.16.163.131]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by coco.kroah.org (Postfix) with ESMTPSA id D031C48479; Mon, 24 May 2010 15:38:19 -0700 (PDT) X-Mailbox-Line: From gregkh@clark.site Mon May 24 15:30:16 2010 Message-Id: <20100524223016.785615552@clark.site> User-Agent: quilt/0.48-8.10 Date: Mon, 24 May 2010 15:28:08 -0700 From: Greg KH To: linux-kernel@vger.kernel.org, stable@kernel.org Cc: stable-review@kernel.org, torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, Ext4 Developers List , "Theodore Tso" , "Jayson R. King" , "Aneesh Kumar K.V" Subject: [12/24] ext4: Implement range_cyclic in ext4_da_writepages instead of write_cache_pages In-Reply-To: <20100524223544.GA13721@kroah.com> Sender: linux-ext4-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-ext4@vger.kernel.org 2.6.27-stable review patch. If anyone has any objections, please let us know. ------------------ From: Aneesh Kumar K.V commit 2acf2c261b823d9d9ed954f348b97620297a36b5 upstream. With delayed allocation we lock the page in write_cache_pages() and try to build an in memory extent of contiguous blocks. This is needed so that we can get large contiguous blocks request. If range_cyclic mode is enabled, write_cache_pages() will loop back to the 0 index if no I/O has been done yet, and try to start writing from the beginning of the range. That causes an attempt to take the page lock of lower index page while holding the page lock of higher index page, which can cause a dead lock with another writeback thread. The solution is to implement the range_cyclic behavior in ext4_da_writepages() instead. http://bugzilla.kernel.org/show_bug.cgi?id=12579 Signed-off-by: Aneesh Kumar K.V Signed-off-by: "Theodore Ts'o" Signed-off-by: Jayson R. King Signed-off-by: Theodore Ts'o Signed-off-by: Greg Kroah-Hartman --- fs/ext4/inode.c | 21 +++++++++++++++++++-- 1 file changed, 19 insertions(+), 2 deletions(-) -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -2456,6 +2456,7 @@ static int ext4_da_writepages(struct add struct inode *inode = mapping->host; int no_nrwrite_index_update; long pages_written = 0, pages_skipped; + int range_cyclic, cycled = 1, io_done = 0; int needed_blocks, ret = 0, nr_to_writebump = 0; struct ext4_sb_info *sbi = EXT4_SB(mapping->host->i_sb); @@ -2493,9 +2494,15 @@ static int ext4_da_writepages(struct add if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX) range_whole = 1; - if (wbc->range_cyclic) + range_cyclic = wbc->range_cyclic; + if (wbc->range_cyclic) { index = mapping->writeback_index; - else + if (index) + cycled = 0; + wbc->range_start = index << PAGE_CACHE_SHIFT; + wbc->range_end = LLONG_MAX; + wbc->range_cyclic = 0; + } else index = wbc->range_start >> PAGE_CACHE_SHIFT; mpd.wbc = wbc; @@ -2509,6 +2516,7 @@ static int ext4_da_writepages(struct add wbc->no_nrwrite_index_update = 1; pages_skipped = wbc->pages_skipped; +retry: while (!ret && wbc->nr_to_write > 0) { /* @@ -2563,6 +2571,7 @@ static int ext4_da_writepages(struct add pages_written += mpd.pages_written; wbc->pages_skipped = pages_skipped; ret = 0; + io_done = 1; } else if (wbc->nr_to_write) /* * There is no more writeout needed @@ -2571,6 +2580,13 @@ static int ext4_da_writepages(struct add */ break; } + if (!io_done && !cycled) { + cycled = 1; + index = 0; + wbc->range_start = index << PAGE_CACHE_SHIFT; + wbc->range_end = mapping->writeback_index - 1; + goto retry; + } if (pages_skipped != wbc->pages_skipped) printk(KERN_EMERG "This should not happen leaving %s " "with nr_to_write = %ld ret = %d\n", @@ -2578,6 +2594,7 @@ static int ext4_da_writepages(struct add /* Update index */ index += pages_written; + wbc->range_cyclic = range_cyclic; if (wbc->range_cyclic || (range_whole && wbc->nr_to_write > 0)) /* * set the writeback_index so that range_cyclic