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Date: Sun, 25 Feb 2024 21:50:30 -0500
From: Al Viro <viro@kernel.org>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Kent Overstreet <kent.overstreet@linux.dev>,
	Matthew Wilcox <willy@infradead.org>,
	Luis Chamberlain <mcgrof@kernel.org>,
	lsf-pc@lists.linux-foundation.org, linux-fsdevel@vger.kernel.org,
	linux-mm <linux-mm@kvack.org>, Daniel Gomez <da.gomez@samsung.com>,
	Pankaj Raghav <p.raghav@samsung.com>, Jens Axboe <axboe@kernel.dk>,
	Dave Chinner <david@fromorbit.com>, Christoph Hellwig <hch@lst.de>,
	Chris Mason <clm@fb.com>, Johannes Weiner <hannes@cmpxchg.org>
Subject: Re: [LSF/MM/BPF TOPIC] Measuring limits and enhancing buffered IO
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On Sun, Feb 25, 2024 at 05:32:14PM -0800, Linus Torvalds wrote:

> But to take a different example, ext2 just calls
> generic_file_write_iter() *without* taking the inode lock, and does
> locking one page at a time. As far as I know, nobody ever really
> complained.

Uh?  __generic_file_write_iter() doesn't take inode lock, but
generic_file_write_iter() does.  O_APPEND handling aside, there's
also file_remove_privs() in there and it does need that lock.