From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Michael Kerrisk (man-pages)" Subject: Re: [PATCH] update the sync.2 man page Date: Thu, 11 Feb 2016 13:35:30 +0100 Message-ID: <56BC8012.6080900@gmail.com> References: <20160209162134.GA18634@infradead.org> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20160209162134.GA18634-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org> Sender: linux-man-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Christoph Hellwig , linux-man-u79uwXL29TY76Z2rM5mHXA@public.gmane.org Cc: mtk.manpages-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org, linux-fsdevel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: linux-man@vger.kernel.org On 02/09/2016 05:21 PM, Christoph Hellwig wrote: > Clarify the description a bit, and document the Linux data integrity > guarantees. Thanks, Christoph. Applied. Cheers, Michael > Signed-off-by: Christoph Hellwig > > diff --git a/man2/sync.2 b/man2/sync.2 > index 5e222cb..28a42c4 100644 > --- a/man2/sync.2 > +++ b/man2/sync.2 > @@ -35,7 +35,7 @@ > .\" > .TH SYNC 2 2015-08-08 "Linux" "Linux Programmer's Manual" > .SH NAME > -sync, syncfs \- commit buffer cache to disk > +sync, syncfs \- commit filesystem caches to disk > .SH SYNOPSIS > .B #include > .sp > @@ -64,8 +64,8 @@ _GNU_SOURCE > .ad > .SH DESCRIPTION > .BR sync () > -causes all buffered modifications to file metadata and data to be > -written to the underlying filesystems. > +causes all pending modifications to file system metadata and cached file > +data to be written to the underlying filesystems. > > .BR syncfs () > is like > @@ -108,16 +108,21 @@ In glibc 2.2.1 and earlier, > it was "int sync(void)", and > .BR sync () > always returned 0. > -.SH BUGS > + > According to the standard specification (e.g., POSIX.1-2001), > .BR sync () > schedules the writes, but may return before the actual > -writing is done. > -However, since version 1.3.20 Linux does actually wait. > -(This still does not guarantee data integrity: modern disks have > -large caches.) > +writing is done. However Linux waits for I/O completions, > +and thus > +.BR sync () > +or > +.BR syncfs () > +provide the same guarantees as fsync called on every file in > +the system or filesystem respectively. > +.SH BUGS > +Before version 1.3.20 Linux did not wait for I/O to complete > +before returning. > .SH SEE ALSO > -.BR bdflush (2), > .BR fdatasync (2), > .BR fsync (2), > .BR sync (1) > -- > To unsubscribe from this list: send the line "unsubscribe linux-man" in > the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > . > -- Michael Kerrisk Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/ Linux/UNIX System Programming Training: http://man7.org/training/ -- To unsubscribe from this list: send the line "unsubscribe linux-man" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html