linux-ext4 - Re: [f2fs-dev] [PATCH v6 0/9] Support negative dentries on case-insensitive ext4 and f2fs

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Date: Wed, 22 Nov 2023 21:04:14 +0000
From: Al Viro <viro@...iv.linux.org.uk>
To: Theodore Ts'o <tytso@....edu>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>,
	Christian Brauner <brauner@...nel.org>,
	Gabriel Krisman Bertazi <krisman@...e.de>,
	linux-f2fs-devel@...ts.sourceforge.net, ebiggers@...nel.org,
	linux-fsdevel@...r.kernel.org, jaegeuk@...nel.org,
	linux-ext4@...r.kernel.org
Subject: Re: [f2fs-dev] [PATCH v6 0/9] Support negative dentries on
 case-insensitive ext4 and f2fs

On Tue, Nov 21, 2023 at 12:12:15AM -0500, Theodore Ts'o wrote:
> Yeah, agreed, that would be a nice optimization.  However, in the
> unfortunate case where (a) it's non-ASCII, and (b) the input string is
> non-normalized and/or differs in case, we end up scanning some portion
> of the two strings twice; once doing the strcmp, and once doing the
> Unicode slow path.

The first pass is cheap and the second one will be running entirely
from the cache, so I doubt that scanning them twice will be a loss...