From: Mingming Cao Subject: Re: delalloc filesystem corruption Date: Tue, 01 Jul 2008 16:00:35 -0700 Message-ID: <1214953235.6940.37.camel@mingming-laptop> References: <3.0.6.32.20080701000046.025249e0@pop.west.cox.net> <3.0.6.32.20080626221227.0242af78@pop.west.cox.net> <3.0.6.32.20080625135340.02423ed8@pop.west.cox.net> <3.0.6.32.20080625135340.02423ed8@pop.west.cox.net> <3.0.6.32.20080626221227.0242af78@pop.west.cox.net> <3.0.6.32.20080701000046.025249e0@pop.west.cox.net> <3.0.6.32.20080701105417.01ce4958@pop.west.cox.net> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Cc: Theodore Tso , "linux-ext4@vger.kernel.org" To: Gary Hawco Return-path: Received: from e3.ny.us.ibm.com ([32.97.182.143]:33282 "EHLO e3.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758331AbYGAXAq (ORCPT ); Tue, 1 Jul 2008 19:00:46 -0400 Received: from d01relay04.pok.ibm.com (d01relay04.pok.ibm.com [9.56.227.236]) by e3.ny.us.ibm.com (8.13.8/8.13.8) with ESMTP id m61N0gMq017192 for ; Tue, 1 Jul 2008 19:00:42 -0400 Received: from d01av02.pok.ibm.com (d01av02.pok.ibm.com [9.56.224.216]) by d01relay04.pok.ibm.com (8.13.8/8.13.8/NCO v9.0) with ESMTP id m61N0aV7226146 for ; Tue, 1 Jul 2008 19:00:36 -0400 Received: from d01av02.pok.ibm.com (loopback [127.0.0.1]) by d01av02.pok.ibm.com (8.12.11.20060308/8.13.3) with ESMTP id m61N0ZsT015622 for ; Tue, 1 Jul 2008 19:00:36 -0400 In-Reply-To: <3.0.6.32.20080701105417.01ce4958@pop.west.cox.net> Sender: linux-ext4-owner@vger.kernel.org List-ID: On Tue, 2008-07-01 at 10:54 +0000, Gary Hawco wrote: > Ted, > > Thanks for your quick reply. With the newest rc8-based snapshots I am no > longer getting segfaults, unless you wanted me to roll back to the > rc6-based snapshots to reproduce the segfaults. > > Per your latest request I disabled delalloc, and voila, no more data > corruption! Then I enabled delalloc and disabled mballoc and file > corruption to /lib/rc/init.d/nettree returned. So delalloc is the culprit. > > I hope this will help figure this out. > Could you try the following patch? It fixes the problem of update on-disk size too early without block allocation, the problem is introduced unintentionally by another bug fix patch added to the patch queue yesterday. Signed-off-by: Mingming Cao --- fs/ext4/inode.c | 32 ++++++++++++++++++++++++++++++-- 1 file changed, 30 insertions(+), 2 deletions(-) Index: linux-2.6.26-rc8/fs/ext4/inode.c =================================================================== --- linux-2.6.26-rc8.orig/fs/ext4/inode.c 2008-07-01 15:13:00.000000000 -0700 +++ linux-2.6.26-rc8/fs/ext4/inode.c 2008-07-01 15:34:19.000000000 -0700 @@ -1892,6 +1892,31 @@ out: return ret; } +/* + * Check if we should update i_disksize + * when write to the end of file but not require block allocation + */ +static int ext4_da_should_update_i_disksize(struct page *page, + unsigned long offset) +{ + struct buffer_head *head, *bh; + unsigned int curr_off = 0; + + head = page_buffers(page); + bh = head; + do { + unsigned int next_off = curr_off + bh->b_size; + + if ((curr_off >= offset) && + (!buffer_mapped || (buffer_delay(bh))) { + return 0; + } + curr_off = next_off; + } while ((bh = bh->b_this_page) != head); + + return 1; +} + static int ext4_da_write_end(struct file *file, struct address_space *mapping, loff_t pos, unsigned len, unsigned copied, @@ -1901,6 +1926,10 @@ static int ext4_da_write_end(struct file int ret = 0, ret2; handle_t *handle = ext4_journal_current_handle(); loff_t new_i_size; + unsigned long start, end; + + start = pos & (PAGE_CACHE_SIZE - 1); + end = start + copied; /* * generic_write_end() will run mark_inode_dirty() if i_size @@ -1910,8 +1939,7 @@ static int ext4_da_write_end(struct file new_i_size = pos + copied; if (new_i_size > EXT4_I(inode)->i_disksize) - if (!walk_page_buffers(NULL, page_buffers(page), - 0, len, NULL, ext4_bh_unmapped_or_delay)){ + if (ext4_da_should_update_i_disksize(page, end)) /* * Updating i_disksize when extending file without * need block allocation > Thanks again, > Gary > > -- > 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