From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from relay.sgi.com (relay2.corp.sgi.com [137.38.102.29]) by oss.sgi.com (Postfix) with ESMTP id 57FD37CBF for ; Wed, 31 Jul 2013 21:48:09 -0500 (CDT) Received: from cuda.sgi.com (cuda2.sgi.com [192.48.176.25]) by relay2.corp.sgi.com (Postfix) with ESMTP id 3C3D83040BF for ; Wed, 31 Jul 2013 19:48:06 -0700 (PDT) Received: from ipmail05.adl6.internode.on.net (ipmail05.adl6.internode.on.net [150.101.137.143]) by cuda.sgi.com with ESMTP id j8CfakWBI3GqThJq for ; Wed, 31 Jul 2013 19:48:04 -0700 (PDT) Date: Thu, 1 Aug 2013 12:48:00 +1000 From: Dave Chinner Subject: Re: [PATCH 3/3] ext4: Implement FALLOC_FL_COLLAPSE_RANGE Message-ID: <20130801024800.GK7118@dastard> References: <1375281746-15908-1-git-send-email-linkinjeon@gmail.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <1375281746-15908-1-git-send-email-linkinjeon@gmail.com> List-Id: XFS Filesystem from SGI List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: xfs-bounces@oss.sgi.com Sender: xfs-bounces@oss.sgi.com To: Namjae Jeon Cc: elder@kernel.org, tytso@mit.edu, Namjae Jeon , linux-kernel@vger.kernel.org, xfs@oss.sgi.com, hch@infradead.org, bpm@sgi.com, adilger.kernel@dilger.ca, a.sangwan@samsung.com, linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org On Wed, Jul 31, 2013 at 11:42:26PM +0900, Namjae Jeon wrote: > From: Namjae Jeon > > New fallocate flag FALLOC_FL_COLLAPSE_RANGE implementation for Ext4 ..... > + > + punch_start = offset >> EXT4_BLOCK_SIZE_BITS(sb); > + punch_stop = (offset + len) >> EXT4_BLOCK_SIZE_BITS(sb); > + > + rounding = max_t(uint, 1 << EXT4_BLOCK_SIZE_BITS(sb), PAGE_CACHE_SIZE); > + ioffset = offset & ~(rounding - 1); > + > + /* Write out all dirty pages */ > + ret = filemap_write_and_wait_range(inode->i_mapping, ioffset, -1); > + if (ret) > + return ret; > + > + /* Take mutex lock */ > + mutex_lock(&inode->i_mutex); > + > + truncate_pagecache_range(inode, ioffset, -1); Ted, that's invalidating the page cache from the start of the collaspse range to the end of the file. So the ext4 code is doing this bit correctly. Why isn't this in the XFS patches? Clearly the need for this was understood, and, well, this code is obviously copied from the XFS hole punching code. i.e. from xfs_free_file_space(). > + /* Wait for existing dio to complete */ > + ext4_inode_block_unlocked_dio(inode); > + inode_dio_wait(inode); That should be done before invalidating the pagecache.... > + credits = ext4_writepage_trans_blocks(inode); > + handle = ext4_journal_start(inode, EXT4_HT_TRUNCATE, credits); > + if (IS_ERR(handle)) { > + ret = PTR_ERR(handle); > + goto out_dio; > + } > + > + down_write(&EXT4_I(inode)->i_data_sem); > + > + ext4_discard_preallocations(inode); > + > + ret = ext4_es_remove_extent(inode, punch_start, > + EXT_MAX_BLOCKS - punch_start - 1); > + if (ret) > + goto journal_stop; > + > + ret = ext4_ext_remove_space(inode, punch_start, punch_stop - 1); > + if (ret) > + goto journal_stop; So, this code punches out the existing space in the file so that the extent shifting is moving extents into a hole. Why is this in the ext4 code, but not the XFS code? Cheers, Dave. -- Dave Chinner david@fromorbit.com _______________________________________________ xfs mailing list xfs@oss.sgi.com http://oss.sgi.com/mailman/listinfo/xfs