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Subject: Re: [PATCH][man-pages] sync.2: syncfs() now returns errors if
 writeback fails
From:   Jeff Layton <jlayton@kernel.org>
To:     Eric Biggers <ebiggers@kernel.org>
Cc:     mtk.manpages@gmail.com, linux-man@vger.kernel.org,
        linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org
Date:   Wed, 10 Jun 2020 17:19:22 -0400
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References: <20200610103347.14395-1-jlayton@kernel.org>
         <20200610155013.GA1339@sol.localdomain>
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On Wed, 2020-06-10 at 08:50 -0700, Eric Biggers wrote:
> On Wed, Jun 10, 2020 at 06:33:47AM -0400, Jeff Layton wrote:
> > A patch has been merged for v5.8 that changes how syncfs() reports
> > errors. Change the sync() manpage accordingly.
> > 
> > Signed-off-by: Jeff Layton <jlayton@kernel.org>
> > ---
> >  man2/sync.2 | 24 +++++++++++++++++++++++-
> >  1 file changed, 23 insertions(+), 1 deletion(-)
> > 
> > diff --git a/man2/sync.2 b/man2/sync.2
> > index 7198f3311b05..27e04cff5845 100644
> > --- a/man2/sync.2
> > +++ b/man2/sync.2
> > @@ -86,11 +86,26 @@ to indicate the error.
> >  is always successful.
> >  .PP
> >  .BR syncfs ()
> > -can fail for at least the following reason:
> > +can fail for at least the following reasons:
> >  .TP
> >  .B EBADF
> >  .I fd
> >  is not a valid file descriptor.
> > +.TP
> > +.B EIO
> > +An error occurred during synchronization.
> > +This error may relate to data written to any file on the filesystem, or on
> > +metadata related to the filesytem itself.
> > +.TP
> > +.B ENOSPC
> > +Disk space was exhausted while synchronizing.
> > +.TP
> > +.BR ENOSPC ", " EDQUOT
> > +Data was written to a files on NFS or another filesystem which does not
> > +allocate space at the time of a
> > +.BR write (2)
> > +system call, and some previous write failed due to insufficient
> > +storage space.
> >  .SH VERSIONS
> >  .BR syncfs ()
> >  first appeared in Linux 2.6.39;
> > @@ -121,6 +136,13 @@ or
> >  .BR syncfs ()
> >  provide the same guarantees as fsync called on every file in
> >  the system or filesystem respectively.
> > +.PP
> > +In mainline kernel versions prior to 5.8,
> > +.\" commit 735e4ae5ba28c886d249ad04d3c8cc097dad6336
> > +.BR syncfs ()
> > +will only fail with EBADF when passed a bad file descriptor. In 5.8
> > +and later kernels, it will also report an error if one or more inodes failed
> > +to be written back since the last syncfs call.
> 
> The sentence "In mainline kernel versions prior to 5.8, syncfs() will only fail
> with EBADF when passed a bad file descriptor" is ambiguous.  It could mean that
> EBADF can now mean other things too.
> 
> Maybe write: "In mainline kernel versions prior to 5.8, syncfs() will only fail
> when passed a bad file descriptor (EBADF)."
> 
> - Eric

Good point. Fixed in my tree using your verbiage. I'll send out a v2
patch once I give others a chance to comment.

Thanks!
-- 
Jeff Layton <jlayton@kernel.org>