Re: hfsplus volume suddenly inaccessable after 'hfs: recoff %d too large'

From: Vyacheslav Dubeyko <slava@dubeyko.com>
To: htl10@users.sourceforge.net
Cc: Michael Fox <415fox@gmail.com>, linux-fsdevel@vger.kernel.org
Subject: Re: hfsplus volume suddenly inaccessable after 'hfs: recoff %d too large'
Date: Sun, 7 Apr 2013 16:12:03 +0400	[thread overview]
Message-ID: <2A43A957-0651-4262-8E7A-2475A594820F@dubeyko.com> (raw)
In-Reply-To: <1365109040.69506.YahooMailClassic@web172301.mail.ir2.yahoo.com>

Hi Hin-Tak,

On Apr 5, 2013, at 12:57 AM, Hin-Tak Leung wrote:

> Hi Michael,
> 
> Argh, that looks suspiciously like the recurring problem I have been trying to pin down for the much of the last year. My current thinking is that one of the patches posted a couple of weeks ago might help.

As I remember, you can easily reproduce the issue that you are investigating. Does the issue reproducible with enabled debug output? Can you reproduce the issue with fully enabled debug output (I mean to enable all debug flags)? If you can reproduce the issue with enabled debug output then could you share this debug output with me?

Thanks,
Vyacheslav Dubeyko.

> That patch addresses out-of-memory conditions in caching of metadata, in a nutshell. I think if (1) the system is under memory stress, (2) one is doing something which transverse the file system very quickly, (3) on a mult-CPU/core system, it is possible to run some mutexed non-re-entrant code in the hfsplus simultaneously without a mutex lock, and therefore get it a bit confused. This idea at least explains why (1) adding an inner mutex lock can delay the problem although supposedly the outer mutex should have prevented more than one copy of the non-re-entrant code from being run and the inner mutex lock should have no effect at all, (2) the on-disk data is always fsck'ed okay - it is just the driver itself getting confused.
> 
> So I have a few questions for you:
> 
> 1. You are on a quad-core system, correct? This is according to your /proc/cpuinfo below.
> 
> 2. You are certainly doing fast file system transversal (updatedb), but are you actually doing it *on top of the hfsplus* file system? I am asking this because updatedb is usually configured not the index removable media under /mnt or /media . But you mentioned you have the hfsplus system mounted under /home - please confirm that and include some more details if you can.
> 
> 3. How full and populous is that hfs+ file system? i.e. the output of both "df" and "df -i" while it is mounted. Is this your Mac OS X system (root / ) disk?
> 
> 4. Is your system under memory stress at the moment the problem happens - e.g. you have a web browser with a few hundred tabs open?
> 
> Hin-Tak
> 
> --- On Thu, 4/4/13, Vyacheslav Dubeyko <slava@dubeyko.com> wrote:
> 