From: Theodore Ts'o Subject: Re: [RFC PATCH] coredump: avoid ext4 auto_da_alloc for core file Date: Mon, 4 Jul 2016 11:11:37 -0400 Message-ID: <20160704151137.GE29557@thunk.org> References: <5cdda475417b2719dced162cce89a283153cb818.1466012020.git.osandov@fb.com> <20160629183444.GA3030@vader> <20160704022455.GA28883@thunk.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Al Viro , linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org, kernel-team@fb.com To: Omar Sandoval Return-path: Content-Disposition: inline In-Reply-To: <20160704022455.GA28883@thunk.org> Sender: linux-fsdevel-owner@vger.kernel.org List-Id: linux-ext4.vger.kernel.org On Sun, Jul 03, 2016 at 10:24:55PM -0400, Theodore Ts'o wrote: > From bf21c027d84ded545d2c08fa01fd184d29641458 Mon Sep 17 00:00:00 2001 > From: Theodore Ts'o > Date: Sun, 3 Jul 2016 22:20:49 -0400 > Subject: [PATCH] ext4: in ext4_setattr(), only call ext4_truncate() if there is no data to drop > > If there are no blocks associated with the inode (and no inline data), > there's no point calling ext4_truncate(). This avoids setting the > replace-via-truncate hueristic if there is an attempt to truncate a > file which is already zero-length --- which is something that happens > in the core dumping code, in case there is an already existing core > file. In the comon case, there is not a previous core file, so by not > enabling the replace-via-truncate hueristic, we can speed up core > dumps. > > Reported-by: Omar Sandoval > Signed-off-by: Theodore Ts'o This patch is buggy; when I tried running regression tests, it failed early. So you probably want to skip this. - Ted