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Date:   Fri, 15 Nov 2019 12:36:34 -0500
From:   "Theodore Y. Ts'o" <tytso@mit.edu>
To:     Jan Kara <jack@suse.cz>
Cc:     Sebastian Siewior <bigeasy@linutronix.de>,
        Thomas Gleixner <tglx@linutronix.de>,
        Matthew Wilcox <willy@infradead.org>,
        LKML <linux-kernel@vger.kernel.org>,
        linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org,
        Peter Zijlstra <peterz@infradead.org>,
        Ingo Molnar <mingo@kernel.org>,
        Anna-Maria Gleixner <anna-maria@linutronix.de>,
        Steven Rostedt <rostedt@goodmis.org>,
        Julia Cartwright <julia@ni.com>,
        Alexander Viro <viro@zeniv.linux.org.uk>,
        Jan Kara <jack@suse.com>, Mark Fasheh <mark@fasheh.com>,
        Joseph Qi <joseph.qi@linux.alibaba.com>,
        Christoph Hellwig <hch@infradead.org>,
        Joel Becker <jlbec@evilplan.org>
Subject: Re: [PATCH] fs/buffer: Make BH_Uptodate_Lock bit_spin_lock a regular
 spinlock_t
Message-ID: <20191115173634.GC23689@mit.edu>
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On Fri, Nov 15, 2019 at 03:56:38PM +0100, Jan Kara wrote:
> With some effort, we could even shrink struct buffer_head from 104 bytes
> (on x86_64) to 96 bytes but I don't think that effort is worth it (I'd find
> it better use of time to actually work on getting rid of buffer heads
> completely).

Is that really realistic?  All aside from the very large number of
file systems which use buffer_heads that would have to be reworked,
the concept of buffer heads is pretty fundamental to how jbd2 is
architected.

					- Ted