From: Andrew Morton <akpm@linux-foundation.org>
To: Christoph Hellwig <hch@infradead.org>
Cc: Dave Chinner <david@fromorbit.com>,
linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 05/17] fs: icache lock i_count
Date: Thu, 30 Sep 2010 23:04:16 -0700 [thread overview]
Message-ID: <20100930230416.868e6468.akpm@linux-foundation.org> (raw)
In-Reply-To: <20101001055536.GD32349@infradead.org>
On Fri, 1 Oct 2010 01:55:36 -0400 Christoph Hellwig <hch@infradead.org> wrote:
> On Wed, Sep 29, 2010 at 09:52:29PM -0700, Andrew Morton wrote:
> > On Wed, 29 Sep 2010 22:18:37 +1000 Dave Chinner <david@fromorbit.com> wrote:
> >
> > > - if (atomic_read(&inode->i_count) != 1)
> > > + if (inode->i_count != 1)
> >
> > This really should have been renamed to catch unconverted code.
> >
> > Such code usually wouldn't compile anyway, but it will if it takes the
> > address of i_count only (for example).
>
> If people do whacky things they'll lose - there is a reason why C has a
> fairly strict type system after all. We've changed types of variables
> all the time and we didn't run into problems.
No, we've run into problems *frequently*. A common case is where we
convert a mutex to a spinlock or vice versa. If you don't rename the
lock, the code still compiles (with warnings) and crashes horridly at
runtime.
> > And maybe we should access this guy via accessor functions, dunno.
>
> Seems like complete overkill.
Still wrong. We do this frequently and we do it in areas where we
believe that the implementation might change in the future.
Had we done it with i_count from day one then this part of the patchset
would be far simpler.
next prev parent reply other threads:[~2010-10-01 6:04 UTC|newest]
Thread overview: 111+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-09-29 12:18 [PATCH 0/17] fs: Inode cache scalability Dave Chinner
2010-09-29 12:18 ` [PATCH 01/17] kernel: add bl_list Dave Chinner
2010-09-30 4:52 ` Andrew Morton
2010-10-16 7:55 ` Nick Piggin
2010-10-16 16:28 ` Christoph Hellwig
2010-10-01 5:48 ` Christoph Hellwig
2010-09-29 12:18 ` [PATCH 02/17] fs: icache lock s_inodes list Dave Chinner
2010-10-01 5:49 ` Christoph Hellwig
2010-10-16 7:54 ` Nick Piggin
2010-10-16 16:12 ` Christoph Hellwig
2010-10-16 17:09 ` Nick Piggin
2010-10-17 0:42 ` Christoph Hellwig
2010-10-17 2:03 ` Nick Piggin
2010-09-29 12:18 ` [PATCH 03/17] fs: icache lock inode hash Dave Chinner
2010-09-30 4:52 ` Andrew Morton
2010-09-30 6:13 ` Dave Chinner
2010-10-01 6:06 ` Christoph Hellwig
2010-10-16 7:57 ` Nick Piggin
2010-09-29 12:18 ` [PATCH 04/17] fs: icache lock i_state Dave Chinner
2010-10-01 5:54 ` Christoph Hellwig
2010-10-16 7:54 ` Nick Piggin
2010-09-29 12:18 ` [PATCH 05/17] fs: icache lock i_count Dave Chinner
2010-09-30 4:52 ` Andrew Morton
2010-10-01 5:55 ` Christoph Hellwig
2010-10-01 6:04 ` Andrew Morton [this message]
2010-10-01 6:16 ` Christoph Hellwig
2010-10-01 6:23 ` Andrew Morton
2010-09-29 12:18 ` [PATCH 06/17] fs: icache lock lru/writeback lists Dave Chinner
2010-09-30 4:52 ` Andrew Morton
2010-09-30 6:16 ` Dave Chinner
2010-10-16 7:55 ` Nick Piggin
2010-10-01 6:01 ` Christoph Hellwig
2010-10-05 22:30 ` Dave Chinner
2010-09-29 12:18 ` [PATCH 07/17] fs: icache atomic inodes_stat Dave Chinner
2010-09-30 4:52 ` Andrew Morton
2010-09-30 6:20 ` Dave Chinner
2010-09-30 6:37 ` Andrew Morton
2010-10-16 7:56 ` Nick Piggin
2010-09-29 12:18 ` [PATCH 08/17] fs: icache protect inode state Dave Chinner
2010-10-01 6:02 ` Christoph Hellwig
2010-10-16 7:54 ` Nick Piggin
2010-09-29 12:18 ` [PATCH 09/17] fs: Make last_ino, iunique independent of inode_lock Dave Chinner
2010-09-30 4:53 ` Andrew Morton
2010-10-01 6:08 ` Christoph Hellwig
2010-10-16 7:54 ` Nick Piggin
2010-09-29 12:18 ` [PATCH 10/17] fs: icache remove inode_lock Dave Chinner
2010-09-29 12:18 ` [PATCH 11/17] fs: Factor inode hash operations into functions Dave Chinner
2010-10-01 6:06 ` Christoph Hellwig
2010-10-16 7:54 ` Nick Piggin
2010-09-29 12:18 ` [PATCH 12/17] fs: Introduce per-bucket inode hash locks Dave Chinner
2010-09-30 1:52 ` Christoph Hellwig
2010-09-30 2:43 ` Dave Chinner
2010-10-16 7:55 ` Nick Piggin
2010-09-29 12:18 ` [PATCH 13/17] fs: Implement lazy LRU updates for inodes Dave Chinner
2010-09-30 2:05 ` Christoph Hellwig
2010-10-16 7:54 ` Nick Piggin
2010-09-29 12:18 ` [PATCH 14/17] fs: Inode counters do not need to be atomic Dave Chinner
2010-09-29 12:18 ` [PATCH 15/17] fs: inode per-cpu last_ino allocator Dave Chinner
2010-09-30 2:07 ` Christoph Hellwig
2010-10-06 6:29 ` Dave Chinner
2010-10-06 8:51 ` Christoph Hellwig
2010-09-30 4:53 ` Andrew Morton
2010-09-30 5:36 ` Eric Dumazet
2010-09-30 7:53 ` Eric Dumazet
2010-09-30 8:14 ` Andrew Morton
2010-09-30 10:22 ` [PATCH] " Eric Dumazet
2010-09-30 16:45 ` Andrew Morton
2010-09-30 17:28 ` Eric Dumazet
2010-09-30 17:39 ` Andrew Morton
2010-09-30 18:05 ` Eric Dumazet
2010-10-01 6:12 ` Christoph Hellwig
2010-10-01 6:45 ` Eric Dumazet
2010-10-16 6:36 ` Nick Piggin
2010-10-16 6:40 ` Nick Piggin
2010-09-29 12:18 ` [PATCH 16/17] fs: Convert nr_inodes to a per-cpu counter Dave Chinner
2010-09-30 2:12 ` Christoph Hellwig
2010-09-30 4:53 ` Andrew Morton
2010-09-30 6:10 ` Dave Chinner
2010-10-16 7:55 ` Nick Piggin
2010-10-16 8:29 ` Eric Dumazet
2010-10-16 9:07 ` Andrew Morton
2010-10-16 9:31 ` Eric Dumazet
2010-10-16 14:19 ` [PATCH] percpu_counter : add percpu_counter_add_fast() Eric Dumazet
2010-10-18 15:24 ` Christoph Lameter
2010-10-18 15:39 ` Eric Dumazet
2010-10-18 16:12 ` Christoph Lameter
2010-10-21 22:37 ` Andrew Morton
2010-10-21 23:10 ` Christoph Lameter
2010-10-22 0:45 ` Andrew Morton
2010-10-22 1:55 ` Andrew Morton
2010-10-22 1:58 ` Nick Piggin
2010-10-22 2:14 ` Andrew Morton
2010-10-22 4:12 ` Eric Dumazet
2010-10-21 22:43 ` Andrew Morton
2010-10-21 22:58 ` Eric Dumazet
2010-10-21 23:18 ` Andrew Morton
2010-10-21 23:22 ` Eric Dumazet
2010-10-21 22:31 ` [PATCH 16/17] fs: Convert nr_inodes to a per-cpu counter Andrew Morton
2010-10-21 22:58 ` Eric Dumazet
2010-10-02 16:02 ` Christoph Hellwig
2010-09-29 12:18 ` [PATCH 17/17] fs: Clean up inode reference counting Dave Chinner
2010-09-30 2:15 ` Christoph Hellwig
2010-10-16 7:55 ` Nick Piggin
2010-10-16 16:14 ` Christoph Hellwig
2010-10-16 17:09 ` Nick Piggin
2010-09-30 4:53 ` Andrew Morton
2010-09-29 23:57 ` [PATCH 0/17] fs: Inode cache scalability Christoph Hellwig
2010-09-30 0:24 ` Dave Chinner
2010-09-30 2:21 ` Christoph Hellwig
2010-10-02 23:10 ` Carlos Carvalho
2010-10-04 7:22 ` Dave Chinner
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