On Sat, May 16, 2015 at 04:26:33PM +0200, Holger Hoffstätte wrote:
> > playing with lazytime on 4.0.4-rc1 + yesterday's fencepost patch) I noticed
> > something odd. Mounting secondary (non-root) partitions with lazytime works
> > fine, but / does not seem to retain the value from fstab - apparently because
> > it is remounted rw during boot, and lazytime gets swallowed/undone.
> >
> > Same effect when trying to remount manually with lazytime:
> >
> > tux>findmnt /
> > TARGET SOURCE FSTYPE OPTIONS
> > / /dev/sda1 ext4 rw,noatime
> >
> > tux>mount -o lazytime,remount /
> >
> > tux>dmesg
> > [ 5208.482505] EXT4-fs (sda1): re-mounted. Opts: (null)
> >
> > tux>findmnt /
> > TARGET SOURCE FSTYPE OPTIONS
> > / /dev/sda1 ext4 rw,noatime
> >
> > tux>mount --version
> > mount from util-linux 2.26.2 (libmount 2.26.0: assert, debug)
> >
> > Newly mounting unmounted partitions works fine.
> >
> > Any ideas?
>
> This turned out to be a regression in util-linux 2.26.x. :-(
I don't think so. Try strace, for example:
# strace -e mount mount -o lazytime,remount /home/archive
mount("/dev/sdb1", "/home/archive", 0xcf1210, MS_REMOUNT|0x2000000, NULL) = 0
^^^^^^^^^
(1<<25) aka 0x2000000 is MS_LAZYTIME
The util-linux since version 2.26.2 supports MS_LAZYTIME flag.
I see the problem on another place. The ext4 fs driver has unique
feature that it's able to accept "lazytime" option as string
(util-linux < 2.26.2) as well as MS_LAZYTIME vfs flag (>= 2.26.2).
IMHO the function ext4_remount() does not check VFS *flags for
MS_LAZYTIME at all. The code probably cares about sb->s_flags only
(these flags are generated by parse_options() when parse options
string). It seems that only MS_RDONLY is expected in *flags.
Ted?
Karel
--
Karel Zak <kzak@xxxxxxxxxx>
http://karelzak.blogspot.com
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