Re: [PATCH] ext4: handle option set by mount flags correctly

[tytso@mit.edu]

On Thu, Jul 23, 2020 at 05:05:26PM +0200, Lukas Czerner wrote:
> Currently there is a problem with mount options that can be both set by
> vfs using mount flags or by a string parsing in ext4.
> 
> i_version/iversion options gets lost after remount, for example
> 
> $ mount -o i_version /dev/pmem0 /mnt
> $ grep pmem0 /proc/self/mountinfo | grep i_version
> 310 95 259:0 / /mnt rw,relatime shared:163 - ext4 /dev/pmem0 rw,seclabel,i_version
> $ mount -o remount,ro /mnt
> $ grep pmem0 /proc/self/mountinfo | grep i_version
> 
> nolazytime gets ignored by ext4 on remount, for example
> 
> $ mount -o lazytime /dev/pmem0 /mnt
> $ grep pmem0 /proc/self/mountinfo | grep lazytime
> 310 95 259:0 / /mnt rw,relatime shared:163 - ext4 /dev/pmem0 rw,lazytime,seclabel
> $ mount -o remount,nolazytime /mnt
> $ grep pmem0 /proc/self/mountinfo | grep lazytime
> 310 95 259:0 / /mnt rw,relatime shared:163 - ext4 /dev/pmem0 rw,lazytime,seclabel
> 
> Fix it by applying the SB_LAZYTIME and SB_I_VERSION flags from *flags to
> s_flags before we parse the option and use the resulting state of the
> same flags in *flags at the end of successful remount.
> 
> Signed-off-by: Lukas Czerner <lczerner@redhat.com>

Thanks, applied.

						- Ted