linux-kernel - Re: [PATCH] fs/read_write: Enable copy_file

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Message-ID: <ZL4cpDxr450zomJ0@dread.disaster.area>
Date:   Mon, 24 Jul 2023 16:39:32 +1000
From:   Dave Chinner <david@...morbit.com>
To:     Nitesh Shetty <nj.shetty@...sung.com>
Cc:     Alexander Viro <viro@...iv.linux.org.uk>,
        Christian Brauner <brauner@...nel.org>, hch@....de,
        gost.dev@...sung.com, Anuj Gupta <anuj20.g@...sung.com>,
        linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] fs/read_write: Enable copy_file_range for block device.

On Mon, Jul 24, 2023 at 11:33:36AM +0530, Nitesh Shetty wrote:
> From: Anuj Gupta <anuj20.g@...sung.com>
> 
> Change generic_copy_file_checks to use ->f_mapping->host for both inode_in
> and inode_out. Allow block device in generic_file_rw_checks.

Why? copy_file_range() is for copying a range of a regular file to
another regular file - why do we want to support block devices for
somethign that is clearly intended for copying data files?

Also, the copy_file_range man page states:

ERRORS
.....
    EINVAL Either fd_in or fd_out is not a regular file.
.....

If we are changing the behavioru of copy_file_range (why?), then man
page updates need to be done as well, documenting the change, which
kernel versions only support regular files, etc.

Cheers,

Dave.
-- 
Dave Chinner
david@...morbit.com