On Sat, Mar 02, 2013 at 01:00:33AM +0100, Jilles Tjoelker wrote: > On Thu, Feb 28, 2013 at 12:21:44AM +0200, Konstantin Belousov wrote: > > On Wed, Feb 27, 2013 at 10:31:42PM +0100, Jilles Tjoelker wrote: > > > While testing recent changes to opendir(), I noticed that fstatfs() does > > > not return the MNT_UNION flag for a -t nullfs -o union mount. As a > > > result, opendir()/readdir() return files that exist in both top and > > > bottom directories twice (at least . and ..). Other -o union mounts and > > > -t unionfs mounts work correctly in this regard. > > > > The below patch passes through just the MNT_UNION flag of the nullfs > > > mount itself. Perhaps more flags should be passed through. > > > > commit fce32a779af4eb977c9b96feb6e4f811d89f2881 > > > Author: Jilles Tjoelker <[email protected]> > > > Date: Sat Feb 23 22:22:39 2013 +0100 > > > > > > nullfs: Preserve the MNT_UNION flag of the nullfs mount itself. > > > > > > This is needed so that opendir() can properly detect a union mount > > > like > > > mount -t nullfs -o union dir1 dir2. > > > > > > diff --git a/sys/fs/nullfs/null_vfsops.c b/sys/fs/nullfs/null_vfsops.c > > > index 3724e0a..ff06f57 100644 > > > --- a/sys/fs/nullfs/null_vfsops.c > > > +++ b/sys/fs/nullfs/null_vfsops.c > > > @@ -313,7 +313,7 @@ nullfs_statfs(mp, sbp) > > > > > > /* now copy across the "interesting" information and fake the rest */ > > > sbp->f_type = mstat.f_type; > > > - sbp->f_flags = mstat.f_flags; > > > + sbp->f_flags = (sbp->f_flags & MNT_UNION) | mstat.f_flags; > > > sbp->f_bsize = mstat.f_bsize; > > > sbp->f_iosize = mstat.f_iosize; > > > sbp->f_blocks = mstat.f_blocks; > > > Would it make sense to preserve more flags from the upper mount ? > > I see a use for MNT_NOEXEC as well, at least. > > Yes, preserving MNT_NOEXEC will make -t nullfs -o noexec work better, in > particular rtld's check for libraries loaded via environment variables. > > In the same way MNT_RDONLY, MNT_NOSUID and MNT_NOSYMFOLLOW could be > preserved. > > On the other hand, MNT_ROOTFS should probably not be passed through from > the underlying filesystem. > > This would give > sbp->f_flags = (sbp->f_flags & (MNT_RDONLY | MNT_NOEXEC | MNT_NOSUID | > MNT_UNION | MNT_NOSYMFOLLOW) | (mstat.f_flags & ~MNT_ROOTFS); I think this is fine.
pgpbxLGJDTdz9.pgp
Description: PGP signature
