From mboxrd@z Thu Jan 1 00:00:00 1970 From: Chris Mason Subject: Re: [PATCH 2/7] writeback: switch to per-bdi threads for flushing data Date: Mon, 16 Mar 2009 09:30:14 -0400 Message-ID: <1237210214.30224.3.camel@think.oraclecorp.com> References: <1236868428-20408-1-git-send-email-jens.axboe@oracle.com> <1236868428-20408-3-git-send-email-jens.axboe@oracle.com> <20090316102253.GB9510@infradead.org> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Cc: Jens Axboe , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, david@fromorbit.com, npiggin@suse.de, linux-mm@kvack.org To: Christoph Hellwig Return-path: In-Reply-To: <20090316102253.GB9510@infradead.org> Sender: owner-linux-mm@kvack.org List-Id: linux-fsdevel.vger.kernel.org On Mon, 2009-03-16 at 06:22 -0400, Christoph Hellwig wrote: > On Thu, Mar 12, 2009 at 03:33:43PM +0100, Jens Axboe wrote: > > +static void bdi_kupdated(struct backing_dev_info *bdi) > > +{ > > + long nr_to_write; > > + struct writeback_control wbc = { > > + .bdi = bdi, > > + .sync_mode = WB_SYNC_NONE, > > + .nr_to_write = 0, > > + .for_kupdate = 1, > > + .range_cyclic = 1, > > + }; > > + > > + sync_supers(); > > Not directly related to your patch, but can someone explain WTF > sync_supers is doing here or in the old kupdated? We're writing back > dirty pages from the VM, and for some reason we try to also write back > superblocks. This doesn't really make any sense. Some of our poor filesystem cousins don't write the super until kupdate kicks them (see ext2_write_super). kupdate has always been the periodic FS thread of last resort. -chris -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org