Re: [PATCH] block: Make write_hints[] big enough

On 10/18/18 9:30 AM, Avri Altman wrote:

quoted

-----Original Message-----
From: Jens Axboe <axboe@kernel.dk>
Sent: Thursday, October 18, 2018 5:38 PM
To: Avri Altman <Avri.Altman@wdc.com>; linux-block@vger.kernel.org
Cc: Avi Shchislowski <redacted>; Alex Lemberg
[off-list ref]
Subject: Re: [PATCH] block: Make write_hints[] big enough

On 10/17/18 10:51 AM, Avri Altman wrote:

quoted

Just stumbled over this.
Looks like the write hints array in the request queue is not allotted
with the required space to accommodate all the write hint types.

fixes: f793dfd3f39a (blk-mq: expose write hints through debugfs)

Your commit message doesn't really explain what you think the issue
is. We have 4 write hint types, with a fifth being "none". Where
are we exceeding these 5 hints?

WRITE_LIFE_EXTREME = RWH_WRITE_LIFE_EXTREME = 5,
will be ignored by queue_write_hint_{show_store}.

Hmm, wonder how that got broken. But we should just bundle NONE
and NOT_SET, since they end up in the same bucket on the
driver side. Making the array larger is not necessary, we
only have effectively 5 hints.

-- 
Jens Axboe