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From: "J. Bruce Fields" <bfields@fieldses.org>
To: NeilBrown <neilb@suse.com>
Cc: Jeff Layton <jlayton@kernel.org>,
	Alexander Viro <viro@zeniv.linux.org.uk>,
	Martin Wilck <mwilck@suse.de>,
	linux-fsdevel@vger.kernel.org,
	Frank Filz <ffilzlnx@mindspring.com>,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH 3/5] fs/locks: change all *_conflict() functions to return a new enum.
Date: Thu, 9 Aug 2018 20:56:26 -0400
Message-ID: <20180810005626.GC3915@fieldses.org> (raw)
In-Reply-To: <87d0urrtvw.fsf@notabene.neil.brown.name>

On Fri, Aug 10, 2018 at 09:40:35AM +1000, NeilBrown wrote:
> caller_fl is first and sys_fl is second.
> 
> if sys_fl, the second, is a read lock, and caller_fl, the first, is a
> write lock, they clearly conflict but any other lock that conflict
> with caller_fl (The write lock) would *not* necessarily conflict with
> the read lock.  So this situation is *not*  FL_TRANSITIVE_CONFLICT.
> 
> locks_conflict() only returns FL_TRANSITIVE_CONFLICT when sys_fl (the
> second) is a write lock, which it isn't in this case.  So I think that
> this case is handled correctly.
> posix_locks_conflict() will return FL_CONFLICT, but not
> FL_TRANSITIVE_CONFLICT.
> 
> Have I convinced you, or have I missed your point?

Eh, I was just confused.

And now I'm tempted to blame you for confusing me, but maybe that's just
my ego going defensive.

(My bruised ego suggests leaving locks_conflict and its callers alone,
and having an entirely separate function that checks this when we need
it.)

--b.

  reply index

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-08-09  2:04 [PATCH 0/5 - V2] locks: avoid thundering-herd wake-ups NeilBrown
2018-08-09  2:04 ` [PATCH 1/5] fs/locks: rename some lists and pointers NeilBrown
2018-08-09  2:04 ` [PATCH 2/5] fs/locks: allow a lock request to block other requests NeilBrown
2018-08-09  2:04 ` [PATCH 3/5] fs/locks: change all *_conflict() functions to return a new enum NeilBrown
2018-08-09 11:09   ` Jeff Layton
2018-08-09 13:09   ` J. Bruce Fields
2018-08-09 23:40     ` NeilBrown
2018-08-10  0:56       ` J. Bruce Fields [this message]
2018-08-09  2:04 ` [PATCH 4/5] fs/locks: split out __locks_wake_one() NeilBrown
2018-08-09  2:04 ` [PATCH 5/5] fs/locks: create a tree of dependent requests NeilBrown
2018-08-09 11:17   ` Jeff Layton
2018-08-09 23:25     ` NeilBrown
2018-08-09 14:13   ` J. Bruce Fields
2018-08-09 22:19     ` NeilBrown
2018-08-10  0:36       ` J. Bruce Fields
2018-08-09 17:32 ` [PATCH 0/5 - V2] locks: avoid thundering-herd wake-ups J. Bruce Fields
2018-08-09 22:12   ` NeilBrown
2018-08-10  0:29     ` J. Bruce Fields
2018-08-10  1:50       ` NeilBrown
2018-08-10  2:52         ` J. Bruce Fields
2018-08-10  3:17           ` NeilBrown
2018-08-10 15:47             ` J. Bruce Fields
2018-08-11 11:56               ` Jeff Layton
2018-08-11 12:35                 ` J. Bruce Fields
2018-08-11 11:51       ` Jeff Layton
2018-08-11 12:21         ` J. Bruce Fields
2018-08-11 13:15           ` Jeff Layton

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