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From: Nick Piggin <npiggin@gmail.com>
To: Yehuda Sadeh Weinraub <yehudasa@gmail.com>
Cc: Nick Piggin <npiggin@kernel.dk>,
	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
	Sage Weil <sage@newdream.net>,
	ceph-devel@vger.kernel.org
Subject: Re: [PATCH 17/46] fs: Use rename lock and RCU for multi-step operations
Date: Thu, 27 Jan 2011 16:18:25 +1100	[thread overview]
Message-ID: <AANLkTinmaojfNDYk1i4jMP33MmEQDur9XZvFp=qhV01e@mail.gmail.com> (raw)
In-Reply-To: <AANLkTi=or1Ya21Am8Dr4KVHgqkwvNxFwgn407=wxRfVa@mail.gmail.com>

On Wed, Jan 26, 2011 at 9:10 AM, Yehuda Sadeh Weinraub
<yehudasa@gmail.com> wrote:
> On Wed, Jan 19, 2011 at 2:32 PM, Nick Piggin <npiggin@gmail.com> wrote:
>> On Thu, Jan 20, 2011 at 9:27 AM, Yehuda Sadeh Weinraub
>> <yehudasa@gmail.com> wrote:
>>> On Tue, Jan 18, 2011 at 2:42 PM, Nick Piggin <npiggin@gmail.com> wrote:
>>>> On Wed, Jan 19, 2011 at 9:32 AM, Yehuda Sadeh Weinraub
>>>
>>>>> There's an issue with ceph as it references the
>>>>> dentry->d_parent(->d_inode) at dentry_release(), so setting
>>>>> dentry->d_parent to NULL here doesn't work with ceph. Though there is
>>>>> some workaround for it, we would like to be sure that this one is
>>>>> really required so that we don't exacerbate the ugliness. The
>>>>> workaround is to keep a pointer to the parent inode in the private
>>>>> dentry structure, which will be referenced only at the .release()
>>>>> callback. This is clearly not ideal.
>>>>
>>>> Hmm, I'll have to think about it. Probably we can check for
>>>> d_count == 0 rather than parent != NULL I think?
>>>>
>>>
>>> That'll solve ceph's problem, don't know about how'd affect other
>>> stuff. We'll need to know whether this is the solution, or whether
>>> we'd need to introduce some other band aid fix.
>>
>> No I think it will work fine. Basically we just need to know whether
>> we have been deleted, and if so then we restart rather than walking
>> back up the parent.
>>
>> I'll send a patch in a few days. For the meantime, it's a rathe
>> small window for ceph to worry about. So we'll have something
>> before -rc2 which should be OK.
>>
>
> I guess that it's a bit late for -rc2, should we assume that it'll be on -rc3?

Yeah, I'm sorry I've been travelling and a bit disconnected.

NFS folk are having a similar problem and looks like similar
proposed fix will do it.

http://marc.info/?l=linux-fsdevel&m=129599823927039&w=2

So I think it is the best way to go to restore behaviour back to what
filesystems already expect, to avoid more surprises in future.

Thanks,
Nick

  reply	other threads:[~2011-01-27  5:18 UTC|newest]

Thread overview: 105+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-11-27 10:15 [PATCH 00/46] rcu-walk and dcache scaling Nick Piggin
2010-11-27  9:44 ` [PATCH 02/46] fs: d_validate fixes Nick Piggin
2010-12-08  1:53   ` Dave Chinner
2010-12-08  6:59     ` Nick Piggin
2010-12-09  0:50       ` Dave Chinner
2010-12-09  0:50         ` Dave Chinner
2010-12-09  4:50         ` Nick Piggin
2010-12-09  4:50           ` Nick Piggin
2010-11-27  9:44 ` [PATCH 03/46] kernel: kmem_ptr_validate considered harmful Nick Piggin
2010-11-27  9:44 ` [PATCH 04/46] fs: dcache documentation cleanup Nick Piggin
2010-11-27  9:44 ` [PATCH 05/46] fs: change d_delete semantics Nick Piggin
2010-11-27  9:44 ` [PATCH 06/46] cifs: dont overwrite dentry name in d_revalidate Nick Piggin
2010-11-27  9:44 ` [PATCH 07/46] jfs: " Nick Piggin
2010-11-27  9:44 ` [PATCH 08/46] fs: change d_compare for rcu-walk Nick Piggin
2010-11-27  9:44 ` [PATCH 09/46] fs: change d_hash " Nick Piggin
2010-11-27  9:44 ` [PATCH 10/46] hostfs: simplify locking Nick Piggin
2010-11-27  9:44 ` [PATCH 11/46] fs: dcache scale hash Nick Piggin
2010-12-09  6:09   ` Dave Chinner
2010-12-09  6:28     ` Nick Piggin
2010-12-09  8:17       ` Dave Chinner
2010-12-09 12:53         ` Nick Piggin
2010-12-09 23:42           ` Dave Chinner
2010-12-10  2:35             ` Nick Piggin
2010-12-10  9:01               ` Dave Chinner
2010-12-13  4:48                 ` Nick Piggin
2010-12-13  5:05                 ` Nick Piggin
2010-11-27  9:44 ` [PATCH 12/46] fs: dcache scale lru Nick Piggin
2010-12-09  7:22   ` Dave Chinner
2010-12-09 12:34     ` Nick Piggin
2010-11-27  9:44 ` [PATCH 13/46] fs: dcache scale dentry refcount Nick Piggin
2010-11-27  9:44 ` [PATCH 14/46] fs: dcache scale d_unhashed Nick Piggin
2010-11-27  9:44 ` [PATCH 15/46] fs: dcache scale subdirs Nick Piggin
2010-11-27  9:44 ` [PATCH 16/46] fs: scale inode alias list Nick Piggin
2010-11-27  9:44 ` [PATCH 17/46] fs: Use rename lock and RCU for multi-step operations Nick Piggin
2011-01-18 22:32   ` Yehuda Sadeh Weinraub
2011-01-18 22:42     ` Nick Piggin
2011-01-19 22:27       ` Yehuda Sadeh Weinraub
2011-01-19 22:32         ` Nick Piggin
2011-01-25 22:10           ` Yehuda Sadeh Weinraub
2011-01-27  5:18             ` Nick Piggin [this message]
2011-02-07 18:52               ` Jim Schutt
2011-02-07 21:04                 ` Yehuda Sadeh Weinraub
2011-02-07 21:04                   ` Yehuda Sadeh Weinraub
2011-02-07 21:31                   ` Jim Schutt
2011-02-07 21:35                     ` Gregory Farnum
2011-02-07 22:25                   ` Jim Schutt
2011-02-14 17:57               ` Yehuda Sadeh Weinraub
2010-11-27  9:44 ` [PATCH 18/46] fs: increase d_name lock coverage Nick Piggin
2010-11-27  9:44 ` [PATCH 19/46] fs: dcache remove dcache_lock Nick Piggin
2010-11-27  9:44 ` [PATCH 20/46] fs: dcache avoid starvation in dcache multi-step operations Nick Piggin
2010-11-27  9:44 ` [PATCH 21/46] fs: dcache reduce dput locking Nick Piggin
2010-11-27  9:44 ` [PATCH 22/46] fs: dcache reduce locking in d_alloc Nick Piggin
2010-11-27  9:44 ` [PATCH 23/46] fs: dcache reduce dcache_inode_lock Nick Piggin
2010-11-27  9:44 ` [PATCH 24/46] fs: dcache rationalise dget variants Nick Piggin
2010-11-27  9:44 ` [PATCH 25/46] fs: dcache reduce d_parent locking Nick Piggin
2010-11-27  9:44 ` [PATCH 26/46] fs: dcache reduce prune_one_dentry locking Nick Piggin
2010-11-27  9:44 ` [PATCH 27/46] fs: reduce dcache_inode_lock width in lru scanning Nick Piggin
2010-11-27  9:44 ` [PATCH 28/46] fs: use RCU in shrink_dentry_list to reduce lock nesting Nick Piggin
2010-11-27  9:44 ` [PATCH 29/46] fs: consolidate dentry kill sequence Nick Piggin
2010-11-27  9:45 ` [PATCH 30/46] fs: icache RCU free inodes Nick Piggin
2010-11-27  9:45 ` [PATCH 31/46] fs: avoid inode RCU freeing for pseudo fs Nick Piggin
2010-11-27  9:45 ` [PATCH 32/46] kernel: optimise seqlock Nick Piggin
2010-11-27  9:45 ` [PATCH 33/46] fs: rcu-walk for path lookup Nick Piggin
2010-11-27  9:45 ` [PATCH 34/46] fs: fs_struct use seqlock Nick Piggin
2010-11-27  9:45 ` [PATCH 35/46] fs: dcache remove d_mounted Nick Piggin
2010-11-27  9:45 ` [PATCH 36/46] fs: dcache reduce branches in lookup path Nick Piggin
2010-11-27  9:45 ` [PATCH 37/46] fs: cache optimise dentry and inode for rcu-walk Nick Piggin
2010-11-27  9:45 ` [PATCH 38/46] fs: prefetch inode data in dcache lookup Nick Piggin
2010-11-27  9:45 ` [PATCH 39/46] fs: d_revalidate_rcu for rcu-walk Nick Piggin
2010-11-27  9:45 ` [PATCH 40/46] fs: provide rcu-walk aware permission i_ops Nick Piggin
2010-11-27  9:45 ` [PATCH 41/46] fs: provide simple rcu-walk ACL implementation Nick Piggin
2010-11-27  9:45 ` [PATCH 42/46] kernel: add bl_list Nick Piggin
2010-11-27  9:45 ` [PATCH 43/46] bit_spinlock: add required includes Nick Piggin
2010-11-27  9:45 ` [PATCH 44/46] fs: dcache per-bucket dcache hash locking Nick Piggin
2010-11-27  9:45 ` [PATCH 45/46] fs: dcache per-inode inode alias locking Nick Piggin
2010-11-27  9:45 ` [PATCH 46/46] fs: improve scalability of pseudo filesystems Nick Piggin
2010-11-27  9:56 ` [PATCH 01/46] Revert "fs: use RCU read side protection in d_validate" Nick Piggin
2010-12-08  1:16   ` Dave Chinner
2010-12-08  9:38     ` Nick Piggin
2010-12-09  0:44       ` Dave Chinner
2010-12-09  4:38         ` Nick Piggin
2010-12-09  5:16           ` Nick Piggin
2010-11-27 15:04 ` [PATCH 00/46] rcu-walk and dcache scaling Anca Emanuel
2010-11-27 15:04   ` Anca Emanuel
2010-11-28  3:28   ` Nick Piggin
2010-11-28  3:28     ` Nick Piggin
2010-11-28  6:24     ` Sedat Dilek
2010-12-01 18:03 ` David Miller
2010-12-03 16:55   ` Nick Piggin
2010-12-07 11:25 ` Dave Chinner
2010-12-07 15:24   ` Nick Piggin
2010-12-07 15:24     ` Nick Piggin
2010-12-07 15:49     ` Peter Zijlstra
2010-12-07 15:59       ` Nick Piggin
2010-12-07 16:23         ` Peter Zijlstra
2010-12-08  3:28     ` Nick Piggin
2010-12-07 21:56 ` Dave Chinner
2010-12-08  1:47   ` Nick Piggin
2010-12-08  3:32     ` Dave Chinner
2010-12-08  4:28       ` Dave Chinner
2010-12-08  7:09         ` Nick Piggin
2010-12-08  7:09           ` Nick Piggin
2010-12-10 20:32           ` Paul E. McKenney
2010-12-12 14:54             ` Paul E. McKenney
2010-12-12 14:54               ` Paul E. McKenney

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