linux-kernel - Re: [GIT PULL 16/20] lightnvm: error handling when whole line is bad

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Message-ID: <C161E678-ADEE-4E05-AC19-B54358005532@cnexlabs.com>
Date:   Mon, 28 May 2018 10:59:03 +0000
From:   Javier Gonzalez <javier@...xlabs.com>
To:     Matias Bjørling <mb@...htnvm.io>
CC:     Jens Axboe <axboe@...com>,
        "linux-block@...r.kernel.org" <linux-block@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        "Konopko, Igor J" <igor.j.konopko@...el.com>,
        Marcin Dziegielewski <marcin.dziegielewski@...el.com>
Subject: Re: [GIT PULL 16/20] lightnvm: error handling when whole line is bad

> On 28 May 2018, at 10.58, Matias Bjørling <mb@...htnvm.io> wrote:
> 
> From: Igor Konopko <igor.j.konopko@...el.com>
> 
> When all the blocks (chunks) in line are marked as bad (offline)
> we shouldn't try to read smeta during init process.
> 
> Currently we are trying to do so by passing -1 as PPA address,
> what causes multiple warnings, that we issuing IOs to out-of-bound
> PPAs.
> 
> Signed-off-by: Igor Konopko <igor.j.konopko@...el.com>
> Signed-off-by: Marcin Dziegielewski <marcin.dziegielewski@...el.com>
> Updated title.
> Signed-off-by: Matias Bjørling <mb@...htnvm.io>
> ---
> drivers/lightnvm/pblk-core.c | 5 +++++
> 1 file changed, 5 insertions(+)
> 
> diff --git a/drivers/lightnvm/pblk-core.c b/drivers/lightnvm/pblk-core.c
> index a20b41c355c5..e3e883547198 100644
> --- a/drivers/lightnvm/pblk-core.c
> +++ b/drivers/lightnvm/pblk-core.c
> @@ -868,6 +868,11 @@ int pblk_line_read_smeta(struct pblk *pblk, struct pblk_line *line)
> {
> 	u64 bpaddr = pblk_line_smeta_start(pblk, line);
> 
> +	if (bpaddr == -1) {
> +		/* Whole line is bad - do not try to read smeta. */
> +		return 1;
> +	}

This case cannot occur on the only user of the function
(pblk_recov_l2p()). On the previous check (pblk_line_was_written()), we
verify the state of the line and the position of the first good chunk. In
the case of a bad line (less chunks than a given threshold to allow
emeta), the recovery will not be carried out in the line.

Javier