From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jensen Date: Sat, 8 Feb 2014 09:26:03 +0800 Subject: [Ocfs2-devel] [patch 09/11] ocfs2: llseek requires ocfs2 inode lock for the file in SEEK_END In-Reply-To: <20140207224409.GS24361@wotan.suse.de> References: <20140124204709.85C895A4203@corp2gmr1-2.hot.corp.google.com> <20140206234253.GR24361@wotan.suse.de> <20140206155029.b7275670913c34ef6bc9a530@linux-foundation.org> <20140207224409.GS24361@wotan.suse.de> Message-ID: <52F587AB.3010604@huawei.com> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: ocfs2-devel@oss.oracle.com On 2014/2/8 6:44, Mark Fasheh wrote: > On Thu, Feb 06, 2014 at 03:50:29PM -0800, Andrew Morton wrote: >> On Thu, 6 Feb 2014 15:42:53 -0800 Mark Fasheh wrote: >> >>> On Fri, Jan 24, 2014 at 12:47:09PM -0800, akpm at linux-foundation.org wrote: >>>> From: Jensen >>>> Subject: ocfs2: llseek requires ocfs2 inode lock for the file in SEEK_END >>>> >>>> llseek requires ocfs2 inode lock for updating the file size in SEEK_END. >>>> because the file size maybe update on another node. >>>> >>>> This bug can be reproduce the following scenario: at first, we dd a test >>>> fileA, the file size is 10k. >>> Basically, you want to amke SEEK_END cluster-aware. This patch would be the >>> right way to do it. >> Sunil was worried about the performance impact. Correctness beats >> performance, but some quantitative testing would be useful? > Performance is my primary concern as well. I thought of writing it up but > realized I don't really have any evidence off the top of my head one way or > the other that this might slow us down. > > That said, I kind of question the usefulness of this patch - we got > along pretty well so far without locking in lseek and some random dd(1) test > doesn't really provide a great end-user reason for why we should do this. > > I will note that gfs2 locks for SEEK_END. > > > Testing would help to answer this, yes. Jensen is this something you can do? > I'm not sure exactly what we would run yet though, I have to think about > that (or maybe someone can suggest something). > > Thanks, > --Mark > ocfs2 is a cluster file system. as like read/write/open/rmdir/unlink interface which think of cluster-aware. I think the seek interface need cluster-aware. May be it has the performance impact. but it's correctness is more important than performance. Thanks, --Jensen > -- > Mark Fasheh > > . >