From: NeilBrown <neilb@suse.de>
To: NeilBrown <neilb@suse.de>
Cc: Dave Chinner <david@fromorbit.com>,
linux-mm@kvack.org, linux-nfs@vger.kernel.org,
linux-kernel@vger.kernel.org, Ming Lei <ming.lei@canonical.com>,
xfs@oss.sgi.com
Subject: Re: [PATCH 04/19] Make effect of PF_FSTRANS to disable __GFP_FS universal.
Date: Thu, 17 Apr 2014 11:03:50 +1000 [thread overview]
Message-ID: <20140417110350.0470feba@notabene.brown> (raw)
In-Reply-To: <20140416161726.51b506e2@notabene.brown>
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On Wed, 16 Apr 2014 16:17:26 +1000 NeilBrown <neilb@suse.de> wrote:
> On Wed, 16 Apr 2014 15:37:56 +1000 Dave Chinner <david@fromorbit.com> wrote:
>
> > On Wed, Apr 16, 2014 at 02:03:36PM +1000, NeilBrown wrote:
> > > - /*
> > > - * Given that we do not allow direct reclaim to call us, we should
> > > - * never be called while in a filesystem transaction.
> > > - */
> > > - if (WARN_ON(current->flags & PF_FSTRANS))
> > > - goto redirty;
> >
> > We still need to ensure this rule isn't broken. If it is, the
> > filesystem will silently deadlock in delayed allocation rather than
> > gracefully handle the problem with a warning....
>
> Hmm... that might be tricky. The 'new' PF_FSTRANS can definitely be set when
> xfs_vm_writepage is called and we really want the write to happen.
> I don't suppose there is any other way to detect if a transaction is
> happening?
I've been thinking about this some more....
That code is in xfs_vm_writepage which is only called as ->writepage.
xfs never calls that directly so it could only possibly be called during
reclaim?
We know that doesn't happen, but if it does then PF_MEMALLOC would be set,
but PF_KSWAPD would not... and you already have a test for that.
How about every time we set PF_FSTRANS, we store the corresponding
xfs_trans_t in current->journal_info, and clear that field when PF_FSTRANS is
cleared. Then xfs_vm_writepage can test for current->journal_info being
clear.
That is the field that several other filesystems use to keep track of the
'current' transaction.
??
I don't know what xfs_trans_t we would use in xfs_bmapi_allocate_worker, but
I suspect you do :-)
Thanks,
NeilBrown
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next prev parent reply other threads:[~2014-04-17 1:04 UTC|newest]
Thread overview: 52+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-04-16 4:03 [PATCH/RFC 00/19] Support loop-back NFS mounts NeilBrown
2014-04-16 4:03 ` [PATCH 08/19] Set PF_FSTRANS while write_cache_pages calls ->writepage NeilBrown
2014-04-16 4:03 ` [PATCH 14/19] driver core: set PF_FSTRANS while holding gdp_mutex NeilBrown
2014-04-16 4:03 ` [PATCH 09/19] XFS: ensure xfs_file_*_read cannot deadlock in memory allocation NeilBrown
2014-04-16 6:04 ` Dave Chinner
2014-04-16 6:27 ` NeilBrown
2014-04-16 6:31 ` Dave Chinner
2014-04-16 4:03 ` [PATCH 10/19] NET: set PF_FSTRANS while holding sk_lock NeilBrown
2014-04-16 5:13 ` Eric Dumazet
2014-04-16 5:47 ` NeilBrown
2014-04-16 13:00 ` David Miller
2014-04-17 2:38 ` NeilBrown
2014-04-16 4:03 ` [PATCH 04/19] Make effect of PF_FSTRANS to disable __GFP_FS universal NeilBrown
2014-04-16 5:37 ` Dave Chinner
2014-04-16 6:17 ` NeilBrown
2014-04-17 1:03 ` NeilBrown [this message]
2014-04-17 4:41 ` Dave Chinner
2014-04-16 4:03 ` [PATCH 07/19] nfsd and VM: use PF_LESS_THROTTLE to avoid throttle in shrink_inactive_list NeilBrown
2014-04-16 4:03 ` [PATCH 12/19] NET: set PF_FSTRANS while holding rtnl_lock NeilBrown
2014-04-16 4:03 ` [PATCH 02/19] lockdep: lockdep_set_current_reclaim_state should save old value NeilBrown
2014-04-16 4:03 ` [PATCH 11/19] FS: set PF_FSTRANS while holding mmap_sem in exec.c NeilBrown
2014-04-16 4:03 ` [PATCH 05/19] SUNRPC: track whether a request is coming from a loop-back interface NeilBrown
2014-04-16 14:47 ` Jeff Layton
2014-04-16 23:25 ` NeilBrown
2014-04-16 4:03 ` [PATCH 06/19] nfsd: set PF_FSTRANS for nfsd threads NeilBrown
2014-04-16 7:28 ` Peter Zijlstra
2014-04-16 4:03 ` [PATCH 01/19] Promote current_{set, restore}_flags_nested from xfs to global NeilBrown
2014-04-16 4:03 ` [PATCH 03/19] lockdep: improve scenario messages for RECLAIM_FS errors NeilBrown
2014-04-16 7:22 ` Peter Zijlstra
2014-04-16 4:03 ` [PATCH 13/19] MM: set PF_FSTRANS while allocating per-cpu memory to avoid deadlock NeilBrown
2014-04-16 5:49 ` Dave Chinner
2014-04-16 6:22 ` NeilBrown
2014-04-16 6:30 ` Dave Chinner
2014-04-16 4:03 ` [PATCH 15/19] nfsd: set PF_FSTRANS when client_mutex is held NeilBrown
2014-04-16 4:03 ` [PATCH 19/19] XFS: set PF_FSTRANS while ilock is held in xfs_free_eofblocks NeilBrown
2014-04-16 6:18 ` Dave Chinner
2014-04-16 4:03 ` [PATCH 16/19] VFS: use GFP_NOFS rather than GFP_KERNEL in __d_alloc NeilBrown
2014-04-16 6:25 ` Dave Chinner
2014-04-16 6:49 ` NeilBrown
2014-04-16 9:00 ` Dave Chinner
2014-04-17 0:51 ` NeilBrown
2014-04-17 5:58 ` Dave Chinner
2014-04-16 4:03 ` [PATCH 18/19] nfsd: set PF_FSTRANS during nfsd4_do_callback_rpc NeilBrown
2014-04-16 4:03 ` [PATCH 17/19] VFS: set PF_FSTRANS while namespace_sem is held NeilBrown
2014-04-16 4:46 ` Al Viro
2014-04-16 5:52 ` NeilBrown
[not found] ` <20140416155230.4d02e4b9-wvvUuzkyo1EYVZTmpyfIwg@public.gmane.org>
2014-04-16 16:37 ` Al Viro
2014-04-16 14:42 ` [PATCH/RFC 00/19] Support loop-back NFS mounts Jeff Layton
2014-04-17 0:20 ` NeilBrown
2014-04-17 1:27 ` Dave Chinner
2014-04-17 1:50 ` NeilBrown
2014-04-17 4:23 ` Dave Chinner
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