From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ted Ts'o Subject: Re: [PATCH v3] introduce sys_syncfs to sync a single file system Date: Mon, 14 Mar 2011 19:17:53 -0400 Message-ID: <20110314231753.GF8120@thunk.org> References: <201103111255.44979.arnd@arndb.de> <20110311235607.GB15853@elie> <9446ab1a2315c0d2476c30f8315a0503.squirrel@webmail.greenhost.nl> <20110312021001.GA16833@elie> <20110312173217.GA24981@kroah.com> <1e597aedd3d7825dcc0630b1cf2399fa.squirrel@webmail.greenhost.nl> <20110314131042.5a7fb32f.akpm@linux-foundation.org> <20110314211119.GC8120@thunk.org> <20110314142032.b9523309.akpm@linux-foundation.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20110314142032.b9523309.akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org> Sender: linux-api-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Andrew Morton Cc: G@thunk.org, Indan Zupancic , Greg KH , Jonathan Nieder , Arnd Bergmann , Sage Weil , linux-fsdevel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, "Aneesh Kumar K. V" , linux-api-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, mtk.manpages-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org, viro-RmSDqhL/yNMiFSDQTTA3OLVCufUGDwFn@public.gmane.org, hch-jcswGhMUV9g@public.gmane.org, l@jasper.es List-Id: linux-api@vger.kernel.org On Mon, Mar 14, 2011 at 02:20:32PM -0700, Andrew Morton wrote: > > I'm a bit nervous about exposing WB_SYNC_NONE to userspace, because > > its semantics are *definitely* hard to describe. For example, at the > > moment if you do a WB_SYNC_NONE writeback, the writeback code will > > clamp the amount of data written back for each inode to > > MAX_WRITEBACK_PAGES (1024) pages. > > Wha? It does? When did that get broken? Oops, sorry, I misread the code in wb_writeback(). My bad! I misinterpreted what write_chunk does in that function. MAX_WRITEBACK_PAGES now really is the minimum amount of pages that wb_writeback() will request the file system to write back. I'm not sure why we bother with write_chunk any more, but it shouldn't be doing any harm any more. - Ted