linux-kernel - Re: [PATCH v4 04/11] fs/9p: Remove unnecessary superblock flags

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Date:   Sat, 18 Feb 2023 18:33:57 +0900
From:   asmadeus@...ewreck.org
To:     Eric Van Hensbergen <ericvh@...nel.org>
Cc:     v9fs-developer@...ts.sourceforge.net, rminnich@...il.com,
        lucho@...kov.net, linux-kernel@...r.kernel.org,
        linux-fsdevel@...r.kernel.org, linux_oss@...debyte.com
Subject: Re: [PATCH v4 04/11] fs/9p: Remove unnecessary superblock flags

Eric Van Hensbergen wrote on Sat, Feb 18, 2023 at 12:33:16AM +0000:
> These flags just add unnecessary extra operations.
> When 9p is run without cache, it inherently implements
> these options so we don't need them in the superblock
> (which ends up sending extraneous fsyncs, etc.).  User
> can still request these options on mount, but we don't
> need to set them as default.

Hm, I don't see where they'd add any operations -- if you have time
would you mind pointing me at some?

As far as I can see, it's just about 'sync' or 'dirsync' in /proc/mounts
and the ST_SYNCHRONOUS statvfs flag; that looks harmless to me and it
looks more correct to keep to me.

(Sorry, didn't take the time to actually try taking a trace; I've
checked the flag itself and the IS_SYNC/IS_DIRSYNC -> inode_needs_sync
wrappers and that only seems used by specific filesystems who'd care
about users setting the mount options, not the other way aorund.)

-- 
Dominique