linux-kernel - Re: [PATCH 0/4] locks: flock and lease related bugfixes, and remove i

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Date:	Tue, 17 Feb 2015 11:55:01 -0800
From:	Linus Torvalds <torvalds@...ux-foundation.org>
To:	Jeff Layton <jeff.layton@...marydata.com>
Cc:	linux-fsdevel <linux-fsdevel@...r.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	"Kirill A. Shutemov" <kirill@...temov.name>,
	"J. Bruce Fields" <bfields@...ldses.org>,
	Christoph Hellwig <hch@....de>,
	Dave Chinner <david@...morbit.com>,
	Sasha Levin <sasha.levin@...cle.com>
Subject: Re: [PATCH 0/4] locks: flock and lease related bugfixes, and remove
 i_flctx counters

Ok, so having gone over these, I think 1, 2 and 4 are fine.

Let's just drop 3. The upgrade clearly does need to drop the old lock
when returning FILE_LOCK_DEFERRED, because otherwise two upgraders
will deadlock waiting for each other.

Oh, and in #1, you might want to remove the "FIXME: add counters to
struct file_lock_context so we don't need to do this?" although that
obviously makes it not strictly a 100% revert.  I do believe that we
should add a "list_count()" function, so that we could write

   *flock_count = list_count(&ctx->flc_flock);

instead of that horribly ugly

    list_for_each_entry(lock, &ctx->flc_flock, fl_list)
         ++(*flock_count);

thing. But that's a separate cleanup.

Can we get that truncated series tested with some flock test suite? I
assume there is *some* filesystem tester that tests some basic flock
stuff, even if it clearly didn't catch the race due to the unlock in
the middle..

                      Linus
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