From: Al Viro <viro@ZenIV.linux.org.uk>
To: Nick Piggin <npiggin@kernel.dk>
Cc: Dave Chinner <david@fromorbit.com>,
linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: Inode Lock Scalability V7 (was V6)
Date: Fri, 22 Oct 2010 04:07:28 +0100 [thread overview]
Message-ID: <20101022030728.GH19804@ZenIV.linux.org.uk> (raw)
In-Reply-To: <20101022023444.GA6573@amd>
On Fri, Oct 22, 2010 at 01:34:44PM +1100, Nick Piggin wrote:
> > * walkers of the sb, wb and hash lists can grab ->i_lock at will;
> > it nests inside their locks.
>
> What about if it is going on or off multiple data structures while
> the inode is live, like inode_lock can protect today. Such as putting
> it on the hash and sb list.
Look at the code. You are overengineering it. We do *not* need a framework
for messing with these lists in arbitrary ways. Where would we need to
do that to an inode we don't hold a reference to or had placed I_FREEING
on and would need i_lock held by caller? Even assuming that we need to
keep [present in hash, present on sb list] in sync (which I seriously doubt),
we can bloody well grab both locks before i_lock.
> > inodes. It's not an accidental subtle property of the code, it's bloody
> > fundamental.
>
> I didn't miss that, and I agree that at the point of my initial lock
> break up, the locking is "wrong". Whether you correct it by changing
> the lock ordering or by using RCU to do lookups is something I want to
> debate further.
>
> I think it is natural to be able to lock the inode and have it lock the
> icache state.
Code outside of fs/inode.c and fs/fs-writeback.c generally has no business
looking at the full icache state, period.
next prev parent reply other threads:[~2010-10-22 3:07 UTC|newest]
Thread overview: 58+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-10-21 0:49 Inode Lock Scalability V6 Dave Chinner
2010-10-21 0:49 ` [PATCH 01/21] fs: switch bdev inode bdi's correctly Dave Chinner
2010-10-21 0:49 ` [PATCH 02/21] kernel: add bl_list Dave Chinner
2010-10-21 0:49 ` [PATCH 03/21] fs: Convert nr_inodes and nr_unused to per-cpu counters Dave Chinner
2010-10-21 0:49 ` [PATCH 04/21] fs: Implement lazy LRU updates for inodes Dave Chinner
2010-10-21 2:14 ` Christian Stroetmann
2010-10-21 10:07 ` Nick Piggin
2010-10-21 12:22 ` Christoph Hellwig
2010-10-23 9:32 ` Al Viro
2010-10-21 0:49 ` [PATCH 05/21] fs: inode split IO and LRU lists Dave Chinner
2010-10-21 0:49 ` [PATCH 06/21] fs: Clean up inode reference counting Dave Chinner
2010-10-21 1:41 ` Christoph Hellwig
2010-10-21 0:49 ` [PATCH 07/21] exofs: use iput() for inode reference count decrements Dave Chinner
2010-10-21 0:49 ` [PATCH 08/21] fs: rework icount to be a locked variable Dave Chinner
2010-10-21 19:40 ` Al Viro
2010-10-21 22:32 ` Dave Chinner
2010-10-21 0:49 ` [PATCH 09/21] fs: Factor inode hash operations into functions Dave Chinner
2010-10-21 0:49 ` [PATCH 10/21] fs: Stop abusing find_inode_fast in iunique Dave Chinner
2010-10-21 0:49 ` [PATCH 11/21] fs: move i_ref increments into find_inode/find_inode_fast Dave Chinner
2010-10-21 0:49 ` [PATCH 12/21] fs: remove inode_add_to_list/__inode_add_to_list Dave Chinner
2010-10-21 0:49 ` [PATCH 13/21] fs: Introduce per-bucket inode hash locks Dave Chinner
2010-10-21 0:49 ` [PATCH 14/21] fs: add a per-superblock lock for the inode list Dave Chinner
2010-10-21 0:49 ` [PATCH 15/21] fs: split locking of inode writeback and LRU lists Dave Chinner
2010-10-21 0:49 ` [PATCH 16/21] fs: Protect inode->i_state with the inode->i_lock Dave Chinner
2010-10-22 1:56 ` Al Viro
2010-10-22 2:26 ` Nick Piggin
2010-10-22 3:14 ` Dave Chinner
2010-10-22 10:37 ` Al Viro
2010-10-22 11:40 ` Christoph Hellwig
2010-10-23 21:40 ` Al Viro
2010-10-23 21:37 ` Al Viro
2010-10-24 14:13 ` Christoph Hellwig
2010-10-24 16:21 ` Christoph Hellwig
2010-10-24 19:17 ` Al Viro
2010-10-24 20:04 ` Christoph Hellwig
2010-10-24 20:36 ` Al Viro
2010-10-24 2:18 ` Nick Piggin
2010-10-21 0:49 ` [PATCH 17/21] fs: protect wake_up_inode with inode->i_lock Dave Chinner
2010-10-21 2:17 ` Christoph Hellwig
2010-10-21 13:16 ` Nick Piggin
2010-10-21 0:49 ` [PATCH 18/21] fs: introduce a per-cpu last_ino allocator Dave Chinner
2010-10-21 0:49 ` [PATCH 19/21] fs: icache remove inode_lock Dave Chinner
2010-10-21 2:14 ` Christian Stroetmann
2010-10-21 0:49 ` [PATCH 20/21] fs: Reduce inode I_FREEING and factor inode disposal Dave Chinner
2010-10-21 0:49 ` [PATCH 21/21] fs: do not assign default i_ino in new_inode Dave Chinner
2010-10-21 5:04 ` Inode Lock Scalability V7 (was V6) Dave Chinner
2010-10-21 13:20 ` Nick Piggin
2010-10-21 23:52 ` Dave Chinner
2010-10-22 0:45 ` Nick Piggin
2010-10-22 2:20 ` Al Viro
2010-10-22 2:34 ` Nick Piggin
2010-10-22 2:41 ` Nick Piggin
2010-10-22 2:48 ` Nick Piggin
2010-10-22 3:12 ` Al Viro
2010-10-22 4:48 ` Nick Piggin
2010-10-22 3:07 ` Al Viro [this message]
2010-10-22 4:46 ` Nick Piggin
2010-10-22 5:01 ` Nick Piggin
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