linux-kernel - Re: [PATCH] libnvdimm: rework region badblocks clearing

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Date:   Mon, 1 May 2017 21:26:57 +0000
From:   "Kani, Toshimitsu" <toshi.kani@....com>
To:     "dan.j.williams@...el.com" <dan.j.williams@...el.com>,
        "linux-nvdimm@...ts.01.org" <linux-nvdimm@...ts.01.org>
CC:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "dave.jiang@...el.com" <dave.jiang@...el.com>,
        "vishal.l.verma@...el.com" <vishal.l.verma@...el.com>
Subject: Re: [PATCH] libnvdimm: rework region badblocks clearing

On Sun, 2017-04-30 at 05:39 -0700, Dan Williams wrote:
> Toshi noticed that the new support for a region-level badblocks
> missed the case where errors are cleared due to BTT I/O.
> 
> An initial attempt to fix this ran into a "sleeping while atomic"
> warning due to taking the nvdimm_bus_lock() in the BTT I/O path to
> satisfy the locking requirements of __nvdimm_bus_badblocks_clear().
> However, that lock is not needed since we are not acting any data
> that is subject to change due to a change of state of the bus /
> region. The badblocks instance has its own internal lock to handle
> mutations of the error list.
> 
> So, to make it clear that we are just acting on region devices and
> don't need the lock rename __nvdimm_bus_badblocks_clear() to
> nvdimm_clear_badblocks_regions(). Eliminate the lock and consolidate
> all routines in drivers/nvdimm/bus.c. Also, make some cleanups to
> remove unnecessary casts, make the calling convention of
> nvdimm_clear_badblocks_regions() clearer by replacing struct resource
> with the minimal struct clear_badblocks_context, and use the
> DEVICE_ATTR macro.
> 
> Cc: Dave Jiang <dave.jiang@...el.com>
> Cc: Vishal Verma <vishal.l.verma@...el.com>
> Reported-by: Toshi Kani <toshi.kani@....com>
> Signed-off-by: Dan Williams <dan.j.williams@...el.com>

Confirmed that the clear path to the region-level badblocks works with
the btt workaround and ndctl fix.

Tested-by: Toshi Kani <toshi.kani@....com>

Thanks!
-Toshi