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Date:   Sat, 12 Jun 2021 21:35:13 +0000
From:   Al Viro <viro@zeniv.linux.org.uk>
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Subject: Re: [RFC 4/9] gfs2: Fix mmap + page fault deadlocks (part 1)
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On Sat, Jun 12, 2021 at 09:05:40PM +0000, Al Viro wrote:

> Is the above an accurate description of the mainline situation there?
> In particular, normal read doesn't seem to bother with locks at all.
> What exactly are those cluster locks for in O_DIRECT read?

BTW, assuming the lack of contention, how costly is dropping/regaining
such cluster lock?