From: Dave Chinner <david@fromorbit.com>
To: Christoph Hellwig <hch@infradead.org>
Cc: viro@ZenIV.linux.org.uk, linux-fsdevel@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 3/4] fs: Lock the inode LRU list separately
Date: Thu, 28 Oct 2010 09:24:44 +1100 [thread overview]
Message-ID: <20101027222444.GC2715@dastard> (raw)
In-Reply-To: <20101027090530.GB16443@infradead.org>
On Wed, Oct 27, 2010 at 05:05:30AM -0400, Christoph Hellwig wrote:
> > @@ -537,15 +545,10 @@ void evict_inodes(struct super_block *sb)
> > }
> >
> > inode->i_state |= I_FREEING;
> > - if (!(inode->i_state & (I_DIRTY | I_SYNC)))
> > - percpu_counter_dec(&nr_inodes_unused);
> > + inode_lru_list_del(inode);
> > spin_unlock(&inode->i_lock);
> >
> > - /*
> > - * Move the inode off the IO lists and LRU once I_FREEING is
> > - * set so that it won't get moved back on there if it is dirty.
> > - */
> > - list_move(&inode->i_lru, &dispose);
> > + list_add(&inode->i_lru, &dispose);
> > }
> > spin_unlock(&inode_lock);
> >
> > @@ -582,15 +585,10 @@ int invalidate_inodes(struct super_block *sb)
> > }
> >
> > inode->i_state |= I_FREEING;
> > - if (!(inode->i_state & (I_DIRTY | I_SYNC)))
> > - percpu_counter_dec(&nr_inodes_unused);
> > + inode_lru_list_del(inode);
> > spin_unlock(&inode->i_lock);
>
> with this scheme we now decrement nr_inodes_unused twice - once in
> invalidate_inodes/evict_inodes and once in dispose_one_inode.
That doesn't happen because the counter is only modified when
the inode is moved on/off the list and there are checks to avoid
removing an inode that is not on the list. Also, the inode is not
removed from the LRU in dispose_one_inode - it is always done when
the inode is marked I_FREEING while the i_lock is held before
calling dispose_one_inode().
Basically I wanted to remove the strange "inode is not on the LRU if
it is dirty or under writeback" accounting checks and make the
accounting symmetric with adding/removing the inodes from the LRU.
These are protected by list_empty() checks, so should always end up
with the correct accounting.
hence the only special case now is prune_icache() which already
holds the inode_lru_lock() so can't call the helper. Besides, we
don't need any checks there because we know the inode is on the LRU
already....
Cheers,
Dave.
--
Dave Chinner
david@fromorbit.com
next prev parent reply other threads:[~2010-10-27 22:24 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-10-27 4:23 fs: break out inode LRU operations from node_lock Dave Chinner
2010-10-27 4:23 ` [PATCH 1/4] fs: protect inode->i_state with inode->i_lock Dave Chinner
2010-10-27 7:07 ` Christian Stroetmann
2010-10-27 8:58 ` Christoph Hellwig
2010-10-27 4:23 ` [PATCH 2/4] fs: factor inode disposal Dave Chinner
2010-10-27 7:55 ` Christoph Hellwig
2010-10-27 9:06 ` Christoph Hellwig
2010-10-27 4:23 ` [PATCH 3/4] fs: Lock the inode LRU list separately Dave Chinner
2010-10-27 7:08 ` Christian Stroetmann
2010-10-27 9:05 ` Christoph Hellwig
2010-10-27 22:24 ` Dave Chinner [this message]
2010-10-28 10:25 ` Christoph Hellwig
2010-10-28 10:58 ` Dave Chinner
2010-10-27 4:23 ` [PATCH 4/4] fs: remove inode_lock from iput_final and prune_icache Dave Chinner
2010-10-27 4:40 ` Al Viro
2010-10-27 4:47 ` Eric Dumazet
2010-10-27 5:25 ` Al Viro
2010-10-27 5:50 ` Eric Dumazet
2010-10-27 6:01 ` Al Viro
2010-10-27 6:09 ` Davidlohr Bueso
2010-10-27 7:11 ` Christian Stroetmann
2010-10-27 9:12 ` Dave Chinner
-- strict thread matches above, loose matches on Subject: below --
2010-10-27 23:02 fs: break out inode LRU operations from inode_lock V2 Dave Chinner
2010-10-27 23:02 ` [PATCH 3/4] fs: Lock the inode LRU list separately Dave Chinner
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