Re: [RFC 4/9] gfs2: Fix mmap + page fault deadlocks (part 1)

[Al Viro]

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?