linux-kernel - Re: [PATCH] lightnvm: pblk: assume that chunks are closed on 1.2 devices

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Date:   Tue, 26 Jun 2018 10:41:54 +0200
From:   Matias Bjørling <mb@...htnvm.io>
To:     hans.ml.holmberg@...tronix.com
Cc:     linux-block@...r.kernel.org, linux-kernel@...r.kernel.org,
        javier@...xlabs.com, hans.holmberg@...xlabs.com
Subject: Re: [PATCH] lightnvm: pblk: assume that chunks are closed on 1.2
 devices

On 06/19/2018 11:06 AM, Hans Holmberg wrote:
> From: Hans Holmberg <hans.holmberg@...xlabs.com>
> 
> We can't know if a block is closed or not on 1.2 devices, so assume
> closed state to make sure that blocks are erased before writing.
> 
> Fixes: 32ef9412c114 ("lightnvm: pblk: implement get log report chunk")
> 
> Signed-off-by: Hans Holmberg <hans.holmberg@...xlabs.com>
> ---
> 
> This patch applies on:
> ssh://github.com/OpenChannelSSD/linux branch for-4.19/core
> 
>   drivers/lightnvm/pblk-init.c | 5 +++--
>   1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/lightnvm/pblk-init.c b/drivers/lightnvm/pblk-init.c
> index aa24264..3b8aa4a 100644
> --- a/drivers/lightnvm/pblk-init.c
> +++ b/drivers/lightnvm/pblk-init.c
> @@ -717,10 +717,11 @@ static int pblk_setup_line_meta_12(struct pblk *pblk, struct pblk_line *line,
>   
>   		/*
>   		 * In 1.2 spec. chunk state is not persisted by the device. Thus
> -		 * some of the values are reset each time pblk is instantiated.
> +		 * some of the values are reset each time pblk is instantiated,
> +		 * so we have to assume that the block is closed.
>   		 */
>   		if (lun_bb_meta[line->id] == NVM_BLK_T_FREE)
> -			chunk->state =  NVM_CHK_ST_FREE;
> +			chunk->state =  NVM_CHK_ST_CLOSED;
>   		else
>   			chunk->state = NVM_CHK_ST_OFFLINE;
>   
> 

pblk should scan (or the lightnvm subsystem) the blocks for their state, 
such that it doesn't have to reinitialize a full drive if it is already 
in a closed state. If marking closed, it does a full erase cycle on 
initialization, which should be avoided since it is a limited resource.