From mboxrd@z Thu Jan 1 00:00:00 1970 Received: by wa-out-1112.google.com with SMTP id m33so1087905wag.8 for ; Thu, 10 Jan 2008 02:53:59 -0800 (PST) Message-ID: <4df4ef0c0801100253m6c08e4a3t917959c030533f80@mail.gmail.com> Date: Thu, 10 Jan 2008 13:53:59 +0300 From: "Anton Salikhmetov" Subject: Re: [PATCH][RFC][BUG] updating the ctime and mtime time stamps in msync() In-Reply-To: <20080110085120.GK25527@unthought.net> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Content-Disposition: inline References: <1199728459.26463.11.camel@codedot> <20080109155015.4d2d4c1d@cuia.boston.redhat.com> <26932.1199912777@turing-police.cc.vt.edu> <20080109170633.292644dc@cuia.boston.redhat.com> <20080109223340.GH25527@unthought.net> <20080109184141.287189b8@bree.surriel.com> <4df4ef0c0801091603y2bf507e1q2b99971c6028d1f3@mail.gmail.com> <20080110085120.GK25527@unthought.net> Sender: owner-linux-mm@kvack.org Return-Path: To: Jakob Oestergaard , Anton Salikhmetov , Rik van Riel , Valdis.Kletnieks@vt.edu, linux-mm@kvack.org, linux-kernel@vger.kernel.org List-ID: 2008/1/10, Jakob Oestergaard : > On Thu, Jan 10, 2008 at 03:03:03AM +0300, Anton Salikhmetov wrote: > ... > > > I guess a third possible time (if we want to minimize the number of > > > updates) would be when natural syncing of the file data to disk, by > > > other things in the VM, would be about to clear the I_DIRTY_PAGES > > > flag on the inode. That way we do not need to remember any special > > > "we already flushed all dirty data, but we have not updated the mtime > > > and ctime yet" state. > > > > > > Does this sound reasonable? > > > > No, it doesn't. The msync() system call called with the MS_ASYNC flag > > should (the POSIX standard requires that) update the st_ctime and > > st_mtime stamps in the same manner as for the MS_SYNC flag. However, > > the current implementation of msync() doesn't call the do_fsync() > > function for the MS_ASYNC case. The msync() function may be called > > with the MS_ASYNC flag before "natural syncing". > > If the update was done as Rik suggested, with the addition that msync() > triggered an explicit sync of the inode data, then everything would be ok, > right? Indeed, if msync() is called with MS_SYNC an explicit sync is triggered, and Rik's suggestion would work. However, the POSIX standard requires a call to msync() with MS_ASYNC to update the st_ctime and st_mtime stamps too. No explicit sync of the inode data is triggered in the current implementation of msync(). Hence Rik's suggestion would fail to satisfy POSIX in the latter case. > > -- > > / jakob > > -- 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