From: Andrew Morton Subject: Re: [PATCH 2/4] ext3: truncate block allocated on a failed ext3_write_begin Date: Wed, 17 Sep 2008 12:22:54 -0700 Message-ID: <20080917122254.a704eff1.akpm@linux-foundation.org> References: <1221319971-29879-1-git-send-email-tytso@mit.edu> <1221319971-29879-2-git-send-email-tytso@mit.edu> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: linux-kernel@vger.kernel.org, aneesh.kumar@linux.vnet.ibm.com, tytso@MIT.EDU, linux-ext4@vger.kernel.org, Nick Piggin To: "Theodore Ts'o" Return-path: Received: from smtp1.linux-foundation.org ([140.211.169.13]:39968 "EHLO smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755919AbYIQTXm (ORCPT ); Wed, 17 Sep 2008 15:23:42 -0400 In-Reply-To: <1221319971-29879-2-git-send-email-tytso@mit.edu> Sender: linux-ext4-owner@vger.kernel.org List-ID: On Sat, 13 Sep 2008 11:32:49 -0400 "Theodore Ts'o" wrote: > From: Aneesh Kumar K.V > > For blocksize < pagesize we need to remove blocks that got allocated in > block_write_begin() if we fail with ENOSPC for later blocks. > block_write_begin() internally does this if it allocated page > locally. This makes sure we don't have blocks outside inode.i_size > during ENOSPC. > > Signed-off-by: Aneesh Kumar K.V > Signed-off-by: "Theodore Ts'o" > Cc: linux-ext4@vger.kernel.org > --- > fs/ext3/inode.c | 7 +++++++ > 1 files changed, 7 insertions(+), 0 deletions(-) > > diff --git a/fs/ext3/inode.c b/fs/ext3/inode.c > index 507d868..bff22b9 100644 > --- a/fs/ext3/inode.c > +++ b/fs/ext3/inode.c > @@ -1178,6 +1178,13 @@ write_begin_failed: > ext3_journal_stop(handle); > unlock_page(page); > page_cache_release(page); > + /* > + * block_write_begin may have instantiated a few blocks > + * outside i_size. Trim these off again. Don't need > + * i_size_read because we hold i_mutex. > + */ > + if (pos + len > inode->i_size) > + vmtruncate(inode, inode->i_size); > } > if (ret == -ENOSPC && ext3_should_retry_alloc(inode->i_sb, &retries)) > goto retry; Well we used to do this trimming in core VFS, but Nick broke it. We still do it if the fs doesn't implement ->write_begin(). Should we do this trimming in pagecache_write_begin() in both cases?