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From: Al Viro <viro@ZenIV.linux.org.uk>
Subject: Re: [PATCH] VFS: Cut down inode->i_op->xyz accesses in path walking
Date: Tue, 26 Jul 2011 19:41:22 +0100
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Cc: Christoph Hellwig <hch@lst.de>,
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To: Linus Torvalds <torvalds@linux-foundation.org>
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On Mon, Jul 25, 2011 at 08:23:38PM -0700, Linus Torvalds wrote:

> The reason I didn't go any further along that way is that we don't
> have any nice atomic operations for small fields like that. The bitops
> want a "long" entity, and it becomes just a nightmare to work out bit
> positions with big-endian etc. And I definitely didn't want to grow
> the inode.

Hmm...  We still have 19 spare bits in ->i_flags and at least 22 in ->i_state.
Do we need to bother with new field at all?  ->i_state is unsigned long...