Re: [PATCH] smb: client: fix cifs_pick_channel when channels are equally loaded

[Paulo Alcantara <pc@manguebit.org>]

Henrique Carvalho <henrique.carvalho@suse.com> writes:

> cifs_pick_channel uses (start % chan_count) when channels are equally
> loaded, but that can return a channel that failed the eligibility
> checks.
>
> Drop the fallback and return the scan-selected channel instead. If none
> is eligible, keep the existing behavior of using the primary channel.
>
> Signed-off-by: Henrique Carvalho <henrique.carvalho@suse.com>
> ---
>  fs/smb/client/transport.c | 17 +++++++++--------
>  1 file changed, 9 insertions(+), 8 deletions(-)
>
> diff --git a/fs/smb/client/transport.c b/fs/smb/client/transport.c
> index 75697f6d2566..26987f261850 100644
> --- a/fs/smb/client/transport.c
> +++ b/fs/smb/client/transport.c
> @@ -807,11 +807,16 @@ cifs_cancelled_callback(struct TCP_Server_Info *server, struct mid_q_entry *mid)
>  }
>  
>  /*
> - * Return a channel (master if none) of @ses that can be used to send
> - * regular requests.
> + * cifs_pick_channel - pick an eligible channel for network operations
>   *
> - * If we are currently binding a new channel (negprot/sess.setup),
> - * return the new incomplete channel.
> + * @ses: session reference
> + *
> + * Select an eligible channel (not terminating and not marked as needing
> + * reconnect), preferring the least loaded one. If no eligible channel is
> + * found, fall back to the primary channel (index 0).
> + *
> + * Return: TCP_Server_Info pointer for the chosen channel, or NULL if @ses is
> + * NULL.
>   */
>  struct TCP_Server_Info *cifs_pick_channel(struct cifs_ses *ses)
>  {
> @@ -850,10 +855,6 @@ struct TCP_Server_Info *cifs_pick_channel(struct cifs_ses *ses)
>  			max_in_flight = server->in_flight;
>  	}
>  
> -	/* if all channels are equally loaded, fall back to round-robin */
> -	if (min_in_flight == max_in_flight)
> -		index = (uint)start % ses->chan_count;
> -

After removing the check, @max_in_flight is no longer neeeded.

Otherwise, looks good.