linux-kernel - Re: [PATCH 23/24] mtd: block2mtd: don't call early_lookup

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Date:   Tue, 23 May 2023 11:34:02 +0200
From:   Miquel Raynal <miquel.raynal@...tlin.com>
To:     Christoph Hellwig <hch@....de>
Cc:     Jens Axboe <axboe@...nel.dk>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Mike Snitzer <snitzer@...nel.org>,
        Joern Engel <joern@...ybastard.org>,
        Richard Weinberger <richard@....at>,
        Vignesh Raghavendra <vigneshr@...com>,
        Pavel Machek <pavel@....cz>, dm-devel@...hat.com,
        linux-kernel@...r.kernel.org, linux-block@...r.kernel.org,
        linux-mtd@...ts.infradead.org, linux-pm@...r.kernel.org
Subject: Re: [PATCH 23/24] mtd: block2mtd: don't call early_lookup_bdev
 after the system is running

Hi Christoph,

hch@....de wrote on Tue, 23 May 2023 09:45:34 +0200:

> early_lookup_bdev is supposed to only be called from the early boot
> code, but mdtblock_early_get_bdev is called as a general fallback when
> lookup_bdev fails, which is problematic because early_lookup_bdev
> bypasses all normal path based permission checking, and might cause
> problems with certain container environments renaming devices.
> 
> Switch to only call early_lookup_bdev when dm is built-in and the system
> state in not running yet.
> 
> Note that this strictly speaking changes the kernel ABI as the PARTUUID=
> and PARTLABEL= style syntax is now not available during a running
> systems.  They never were intended for that, but this breaks things
> we'll have to figure out a way to make them available again.  But if
> avoidable in any way I'd rather avoid that.

Sounds reasonable to me. Richard?

Reviewed-by: Miquel Raynal <miquel.raynal@...tlin.com>

Thanks,
Miquèl