From mboxrd@z Thu Jan 1 00:00:00 1970 From: Chris Mason Subject: Re: [PATCH] btrfs: don't return EINTR Date: Tue, 17 Apr 2012 15:34:17 -0400 Message-ID: <20120417193417.GU28915@shiny> References: <1334408175-6568-1-git-send-email-sensille@gmx.net> <4F8D7B04.9050904@gmx.net> <20120417152401.GL28915@shiny> <20120417182219.GA4143@localhost.localdomain> <4F8DBCCB.10904@gmx.net> <20120417191424.GB4143@localhost.localdomain> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Arne Jansen , linux-btrfs@vger.kernel.org To: Josef Bacik Return-path: In-Reply-To: <20120417191424.GB4143@localhost.localdomain> List-ID: On Tue, Apr 17, 2012 at 03:14:24PM -0400, Josef Bacik wrote: > On Tue, Apr 17, 2012 at 08:56:11PM +0200, Arne Jansen wrote: > > On 04/17/12 20:22, Josef Bacik wrote: > > >On Tue, Apr 17, 2012 at 11:24:01AM -0400, Chris Mason wrote: > > >>On Tue, Apr 17, 2012 at 04:15:32PM +0200, Arne Jansen wrote: > > >>>On 14.04.2012 14:56, Arne Jansen wrote: > > >>>>It is basically a good thing if we are interruptible when waiting for > > >>>>free space, but the generality in which it is implemented currently > > >>>>leads to system calls being interruptible that are not documented this > > >>>>way. For example git can't handle interrupted unlink(), leading to > > >>>>corrupt repos under space pressure. > > >>> > > >>>Is this patch a candidate for the next rc? > > >> > > >>The EINTR came from Josef. We do want to be able to break out of long > > >>flushes, but I want to check with him to see if there was a specific bug > > >>this was solving? > > > > > >Sorry I was -ENOINTERNET, no the only thing I was fixing was being able to break > > >out of long flushes. Maybe instead of using the big hammer here we just make > > >unlink ignore EINTR and try again, or maybe pass down a flag saying I can't be > > >interrupted? Thanks, > > > > > > > unlink() is the only call I've seen problems with, but there are > > probably other calls where EINTR is also unexpected. > > Also, just retrying the unlink internally won't help as the signal > > is still pending. > > How can we gather a list of calls where EINTR is ok? > > Well then passing a flag down that says we can't interrupt I guess is what we're > going to have to do and just wait uninterruptible. I think our best bet is to > just fix them as they come up, I thought all system calls could return EINTR but > apparently I was wrong :). Thanks, I'd guess that EINTR is unexpected most of the time. Including in reads and writes. The real question is how long we might end up waiting? -chris