linux-kernel - Re: [PATCH v4 07/10] tmpfs: Add casefold lookup support

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Message-ID: <c547e1aa-f894-409e-9033-f370c5c16171@igalia.com>
Date: Tue, 1 Oct 2024 22:40:17 -0300
From: André Almeida <andrealmeid@...lia.com>
To: Gabriel Krisman Bertazi <gabriel@...sman.be>
Cc: Hugh Dickins <hughd@...gle.com>, Andrew Morton
 <akpm@...ux-foundation.org>, Alexander Viro <viro@...iv.linux.org.uk>,
 Christian Brauner <brauner@...nel.org>, Jan Kara <jack@...e.cz>,
 linux-mm@...ck.org, linux-kernel@...r.kernel.org,
 linux-fsdevel@...r.kernel.org, kernel-dev@...lia.com,
 Daniel Rosenberg <drosen@...gle.com>, smcv@...labora.com,
 Christoph Hellwig <hch@....de>, Theodore Ts'o <tytso@....edu>
Subject: Re: [PATCH v4 07/10] tmpfs: Add casefold lookup support

Hey Krisman,

Em 12/09/2024 16:04, Gabriel Krisman Bertazi escreveu:
> André Almeida <andrealmeid@...lia.com> writes:
> 

[...]

>> +#if IS_ENABLED(CONFIG_UNICODE)
>> +	if (ctx->encoding) {
>> +		sb->s_encoding = ctx->encoding;
>> +		sb->s_d_op = &shmem_ci_dentry_ops;
>> +		if (ctx->strict_encoding)
>> +			sb->s_encoding_flags = SB_ENC_STRICT_MODE_FL;
>> +	}
>>   #else
>> -	sb->s_flags |= SB_NOUSER;
>> +	sb->s_d_op = &simple_dentry_operations;
> 
> Moving simple_dentry_operations to be set at s_d_op should be a separate
> patch.
> 
> It is a change that has non-obvious side effects (i.e. the way we
> treat the root dentry) so it needs proper review by itself.  It is
> also not related to the rest of the case-insensitive patch.
> 

The idea of setting simple_dentry_operations come from my previous 
approach of having our own shmem_lookup(), replacing simple_lookup(). 
Now that we are settled to keep with simple_lookup() anyway (that 
already sets simple_dentry_operations), I think we don't need this 
change anymore, right?

This will be set for every dentry that doesn't have a 
dentry->d_sb->s_d_op. Case-insensitive mount points will have this set, 
so we don't risk overwriting it.