From: "Amit K. Arora" Subject: Re: [PATCH 4/7][TAKE5] support new modes in fallocate Date: Tue, 26 Jun 2007 16:15:46 +0530 Message-ID: <20070626104546.GB19870@amitarora.in.ibm.com> References: <20070511110301.GB28425@in.ibm.com> <20070512080157.GF85884050@sgi.com> <20070612061652.GA6320@amitarora.in.ibm.com> <20070613235217.GS86004887@sgi.com> <20070614091458.GH5181@schatzie.adilger.int> <20070614120413.GD86004887@sgi.com> <20070614193347.GN5181@schatzie.adilger.int> <20070625132810.GA1951@amitarora.in.ibm.com> <20070625134500.GE1951@amitarora.in.ibm.com> <20070625215239.GK5181@schatzie.adilger.int> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii To: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-ext4@vger.kernel.org, David Chinner , suparna@in.ibm.com, cmm@us.ibm.com, xfs@oss.sgi.com Return-path: Content-Disposition: inline In-Reply-To: <20070625215239.GK5181@schatzie.adilger.int> Sender: linux-fsdevel-owner@vger.kernel.org List-Id: linux-ext4.vger.kernel.org On Mon, Jun 25, 2007 at 03:52:39PM -0600, Andreas Dilger wrote: > On Jun 25, 2007 19:15 +0530, Amit K. Arora wrote: > > +#define FA_FL_DEALLOC 0x01 /* default is allocate */ > > +#define FA_FL_KEEP_SIZE 0x02 /* default is extend/shrink size */ > > +#define FA_FL_DEL_DATA 0x04 /* default is keep written data on DEALLOC */ > > In XFS one of the (many) ALLOC modes is to zero existing data on allocate. > For ext4 all this would mean is calling ext4_ext_mark_uninitialized() on > each extent. For some workloads this would be much faster than truncate > and reallocate of all the blocks in a file. In ext4, we already mark each extent having preallocated blocks as uninitialized. This is done as part of following code (which is part of patch 5/7) in ext4_ext_get_blocks() : @@ -2122,6 +2160,8 @@ int ext4_ext_get_blocks(handle_t *handle /* try to insert new extent into found leaf and return */ ext4_ext_store_pblock(&newex, newblock); newex.ee_len = cpu_to_le16(allocated); + if (create == EXT4_CREATE_UNINITIALIZED_EXT) /* Mark uninitialized */ + ext4_ext_mark_uninitialized(&newex); err = ext4_ext_insert_extent(handle, inode, path, &newex); if (err) { /* free data blocks we just allocated */ > In that light, please change the comment to /* default is keep existing data */ > so that it doesn't imply this is only for DEALLOC. Ok. Will update the comment. Thanks! -- Regards, Amit Arora