From mboxrd@z Thu Jan  1 00:00:00 1970
From: "J. Bruce Fields" <bfields@fieldses.org>
Subject: Re: [PATCH v5 13/14] locks: skip deadlock detection on FL_FILE_PVT
 locks
Date: Tue, 14 Jan 2014 16:30:44 -0500
Message-ID: <20140114213044.GD23999@fieldses.org>
References: <1389277187-18211-1-git-send-email-jlayton@redhat.com> <1389277187-18211-14-git-send-email-jlayton@redhat.com> <52CF05B5.5080700@amacapital.net>
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Cc: Richard Hipp <drh@hwaci.com>, Jeff Layton <jlayton@redhat.com>, samba-technical@lists.samba.org, "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	Andy Lutomirski <luto@amacapital.net>, Linux FS Devel <linux-fsdevel@vger.kernel.org>, nfs-ganesha-devel@lists.sourceforge.net
To: Richard Hipp <drh@sqlite.org>
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On Tue, Jan 14, 2014 at 04:21:53PM -0500, Richard Hipp wrote:
> SQLite uses only F_SETLK, never F_SETLKW.  Doesn't that mean that SQLite
> will work the same with or without deadlock detection?  Doesn't deadlock
> detection only come into play with F_SETLKW?

That's correct.

> > >> (Actually, what happens if you receive a signal which waiting on a file
> > lock?)
> > >
> > > Return -EINTR.
> >
> 
> Huh.  SQLite is not checking for EINTR if fcntl(F_SETLK,...) fails.  Should
> it be?  Or does EINTR only come up for F_SETLKW?

I don't know--I wonder if a distributed filesystem, for example, might
allow even a non-blocking lock request to be interrupted?  Might be
interesting to check what nfs does.

--b.

> 
> We do check for EINTR and retry for other system calls (read(), write(),
> fallocate(), ftruncate(), close(), chmod(), open(), maybe others too).