linux-ext4 - Re: [PATCH 1/2] fuse2fs: mount norecovery if main block device is readonly

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Message-ID: <aPFIultQzQd6fk-o@cern.ch>
Date: Thu, 16 Oct 2025 14:34:18 -0500
From: Dave Dykstra <dwd@...n.ch>
To: "Darrick J. Wong" <djwong@...nel.org>
Cc: tytso@....edu, linux-ext4@...r.kernel.org
Subject: Re: [PATCH 1/2] fuse2fs: mount norecovery if main block device is
 readonly

I have a few problems with this patch, details below.

I have proposed an alternative at
    https://github.com/tytso/e2fsprogs/pull/250
and I'll email that here next.

On Mon, Sep 15, 2025 at 05:03:14PM -0700, Darrick J. Wong wrote:
...
> diff --git a/misc/fuse2fs.c b/misc/fuse2fs.c
> index 48473321f469dc..fb44b0a79b53e6 100644
> --- a/misc/fuse2fs.c
> +++ b/misc/fuse2fs.c
> @@ -946,6 +946,15 @@ static errcode_t fuse2fs_open(struct fuse2fs *ff, int libext2_flags)
>  
>  	err = ext2fs_open2(ff->device, options, flags, 0, 0, unix_io_manager,
>  			   &ff->fs);
> +	if (err == EPERM) {

In my case the error here is EACCES (Permission denied) rather than EPERM
so I in my patch I included both.

> +		err_printf(ff, "%s.\n",
> +			   _("read-only device, trying to mount norecovery"));
> +		flags &= ~EXT2_FLAG_RW;
> +		ff->ro = 1;
> +		ff->norecovery = 1;

I don't think it's good to switch to read-only+norecovery even when a
read-write mode was requested.  That goes too far.  It also doesn't
catch when recovery is needed.  My proposed patch only reopens read-only
when ro was requested and then later checks to see if recovery is needed
and if so, errors out.

Dave