On Mon, Dec 14, 2015 at 12:50:37PM -0500, Austin S. Hemmelgarn wrote: > On 2015-12-14 12:32, David Sterba wrote: > > On Thu, Dec 10, 2015 at 10:34:06AM +0800, Qu Wenruo wrote: > >> Introduce a new mount option "nologreplay" to co-operate with "ro" mount > >> option to get real readonly mount, like "norecovery" in ext* and xfs. > >> > >> Since the new parse_options() need to check new flags at remount time, > >> so add a new parameter for parse_options(). > >> > >> Signed-off-by: Qu Wenruo <quwen...@cn.fujitsu.com> > >> Reviewed-by: Chandan Rajendra <chan...@linux.vnet.ibm.com> > >> Tested-by: Austin S. Hemmelgarn <ahferro...@gmail.com> > > > > I've read the discussions around the change and from the user's POV I'd > > suggest to add another mount option that would be just an alias for any > > mount options that would implement the 'hard-ro' semantics. > > > > Say it's called 'nowr'. Now it would imply 'nologreplay', but may cover > > more options in the future. > It should also imply noatime. I'm not sure how BTRFS handles atime when > mounted RO, but I know a lot of old UNIX systems updated atime even on > filesystems mounted RO, and I know that at least at one point Linux did too.
A mount with -o ro will not touch atimes. At one point the read-only snapshots changed atimes, but this has been fixed since. http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/fs/inode.c#n1602 http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/fs/btrfs/inode.c#n5973 > > mount -o ro,nowr /dev/sdx /mnt > > > > would work when switching kernels. > > I like this idea, but I think that having a name like true-ro or hard-ro > and making it imply ro (and noatime) would probably be better (or at > least, simpler to use from a user perspective). Ok, a single option to do the real-ro sounds better than ro,something. -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
