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Subject: Re: Bug/regression: Read-only mount not read-only
To: Austin S Hemmelgarn <ahferroin7@gmail.com>,
        Qu Wenruo <quwenruo@cn.fujitsu.com>,
        Russell Coker <russell@coker.com.au>
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Cc: Chris Mason <clm@fb.com>, Hugo Mills <hugo@carfax.org.uk>,
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From: Eric Sandeen <sandeen@redhat.com>
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Date: Wed, 2 Dec 2015 16:48:27 -0600
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On 12/2/15 11:48 AM, Austin S Hemmelgarn wrote:

> On a side note, do either XFS or ext4 support removing the norecovery
> option from the mount flags through mount -o remount?  Even if they
> don't, that might be a nice feature to have in BTRFS if we can safely
> support it.

It's not remountable today on xfs:

        /* ro -> rw */
        if ((mp->m_flags & XFS_MOUNT_RDONLY) && !(*flags & MS_RDONLY)) {
                if (mp->m_flags & XFS_MOUNT_NORECOVERY) {
                        xfs_warn(mp,
                "ro->rw transition prohibited on norecovery mount");
                        return -EINVAL;
                }

not sure about ext4.

-Eric