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Date: Tue, 7 Nov 2023 22:18:05 +0000
From: Matthew Wilcox <willy@infradead.org>
To: Wedson Almeida Filho <wedsonaf@gmail.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>,
	Christian Brauner <brauner@kernel.org>,
	Kent Overstreet <kent.overstreet@gmail.com>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	linux-fsdevel@vger.kernel.org, rust-for-linux@vger.kernel.org,
	Wedson Almeida Filho <walmeida@microsoft.com>
Subject: Re: [RFC PATCH 10/19] rust: fs: introduce `FileSystem::read_folio`
Message-ID: <ZUq3nZgedcA5CF0V@casper.infradead.org>
References: <20231018122518.128049-1-wedsonaf@gmail.com>
 <20231018122518.128049-11-wedsonaf@gmail.com>
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In-Reply-To: <20231018122518.128049-11-wedsonaf@gmail.com>

On Wed, Oct 18, 2023 at 09:25:09AM -0300, Wedson Almeida Filho wrote:
> @@ -36,6 +39,9 @@ pub trait FileSystem {
>  
>      /// Returns the inode corresponding to the directory entry with the given name.
>      fn lookup(parent: &INode<Self>, name: &[u8]) -> Result<ARef<INode<Self>>>;
> +
> +    /// Reads the contents of the inode into the given folio.
> +    fn read_folio(inode: &INode<Self>, folio: LockedFolio<'_>) -> Result;
>  }
>  

This really shouldn't be a per-filesystem operation.  We have operations
split up into mapping_ops, inode_ops and file_ops for a reason.  In this
case, read_folio() can have a very different implementation for, eg,
symlinks, directories and files.  So we want to have different aops
for each of symlinks, directories and files.  We should maintain that
separation for filesystems written in Rust too.  Unless there's a good
reason to change it, and then we should change it in C too.