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Subject: Re: Regression in squashfs mount option handling in v5.4
To:     Jeremi Piotrowski <jeremi.piotrowski@gmail.com>,
        linux-kernel@vger.kernel.org,
        Linux FS Devel <linux-fsdevel@vger.kernel.org>,
        Al Viro <viro@ZenIV.linux.org.uk>,
        David Howells <dhowells@redhat.com>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Phillip Lougher <phillip@squashfs.org.uk>
References: <20191130181548.GA28459@gentoo-tp.home>
From:   Randy Dunlap <rdunlap@infradead.org>
Message-ID: <6af16095-eab0-9e99-6782-374705d545e4@infradead.org>
Date:   Sat, 30 Nov 2019 10:56:47 -0800
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[adding Cc-s]

On 11/30/19 10:15 AM, Jeremi Piotrowski wrote:
> Hi,
> 
> I'm working on an embedded project which uses 'rauc' as an updater. rauc mounts
> a squashfs image using
> 
>   mount -t squashfs -o ro,loop,sizelimit=xxx squashfs.img /mnt
> 
> On my system mount is busybox, and busybox does not know the sizelimit
> parameter, so it simply passes it on to the mount syscall. The syscall
> arguments end up being:
> 
>   mount("/dev/loop0", "dir", "squashfs", MS_RDONLY|MS_SILENT, "sizelimit=xxx")
> 
> Until kernel 5.4 this worked, since 5.4 this returns EINVAL and dmesg contains
> the line "squashfs: Unknown parameter 'sizelimit'". I believe this has to do
> with the conversion of squashfs to the new mount api. 
> 
> This is an unfortunate regression, and it does not seem like this can be simply
> reverted. What is the suggested course of action?
> 
> Please cc me on replies, I'm not subscribed to the list.
> 
> Thanks,
> Jeremi
> 


-- 
~Randy
Reported-by: Randy Dunlap <rdunlap@infradead.org>