linux-kernel - Re: [PATCH 1/2] cifs: client: force multichannel=off when max

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Message-ID: <da3e2b5a-a5da-4526-9884-8789990ebf95@suse.com>
Date: Mon, 22 Sep 2025 11:41:22 -0300
From: Henrique Carvalho <henrique.carvalho@...e.com>
To: rajasimandalos@...il.com, linux-cifs@...r.kernel.org
Cc: sfrench@...ba.org, pc@...guebit.org, ronniesahlberg@...il.com,
 sprasad@...rosoft.com, tom@...pey.com, bharathsm@...rosoft.com,
 linux-kernel@...r.kernel.org, Rajasi Mandal <rajasimandal@...rosoft.com>
Subject: Re: [PATCH 1/2] cifs: client: force multichannel=off when
 max_channels=1

Hi Rajasi,

On 9/22/25 5:24 AM, rajasimandalos@...il.com wrote:
> From: Rajasi Mandal <rajasimandal@...rosoft.com>
> 
> Previously, specifying both multichannel and max_channels=1 as mount
> options would leave multichannel enabled, even though it is not
> meaningful when only one channel is allowed. This led to confusion and
> inconsistent behavior, as the client would advertise multichannel
> capability but never establish secondary channels.
> 
> Fix this by forcing multichannel to false whenever max_channels=1,
> ensuring the mount configuration is consistent and matches user intent.
> This prevents the client from advertising or attempting multichannel
> support when it is not possible.
> 
> Signed-off-by: Rajasi Mandal <rajasimandal@...rosoft.com>
> ---
>  fs/smb/client/fs_context.c | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/fs/smb/client/fs_context.c b/fs/smb/client/fs_context.c
> index 072383899e81..43552b44f613 100644
> --- a/fs/smb/client/fs_context.c
> +++ b/fs/smb/client/fs_context.c
> @@ -1820,6 +1820,13 @@ static int smb3_fs_context_parse_param(struct fs_context *fc,
>  		goto cifs_parse_mount_err;
>  	}
>  
> +	/*
> +	 * Multichannel is not meaningful if max_channels is 1.
> +	 * Force multichannel to false to ensure consistent configuration.
> +	 */
> +	if (ctx->multichannel && ctx->max_channels == 1)
> +		ctx->multichannel = false;
> +
>  	return 0;
>  
>   cifs_parse_mount_err:

Do we even need ->multichannel flag at all? Maybe we could replace
->multichannel for a function that checks for max_channels > 1?

-- 
Henrique
SUSE Labs