Messages in this thread | | | Date | Sun, 14 Jun 2009 20:16:45 +0800 | From | Wu Fengguang <> | Subject | Re: [PATCH] ramfs: ignore tmpfs options when we emulate it |
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On Sat, Jun 13, 2009 at 10:15:51PM +0800, Hugh Dickins wrote: > On Sat, 13 Jun 2009, Mike Frysinger wrote: > > > On systems where CONFIG_SHMEM is disabled, mounting tmpfs filesystems can > > fail when tmpfs options are used. This is because tmpfs creates a small > > wrapper around ramfs which rejects unknown options, and ramfs itself only > > supports a tiny subset of what tmpfs supports. This makes it pretty hard > > to use the same userspace systems across different configuration systems. > > As such, ramfs should ignore the tmpfs options when tmpfs is merely a > > wrapper around ramfs. > > Yes, indeed, thanks a lot for reporting this. > > But I'm uneasy with making ramfs behaviour differ with CONFIG_SHMEM > (perhaps that's silly: certainly tmpfs behaviour differs with it), > and uneasy with coding a list of options we need to remember to keep > in synch with mm/shmem.c. It's easier to justify ignoring all options, > than rejecting some while ignoring others yet not respecting them. > [snip] > [PATCH] ramfs: ignore unknown mount options > > From: Mike Frysinger <vapier@gentoo.org> > > On systems where CONFIG_SHMEM is disabled, mounting tmpfs filesystems can > fail when tmpfs options are used. This is because tmpfs creates a small > wrapper around ramfs which rejects unknown options, and ramfs itself only > supports a tiny subset of what tmpfs supports. This makes it pretty hard > to use the same userspace systems across different configuration systems. > As such, ramfs should ignore the tmpfs options when tmpfs is merely a > wrapper around ramfs. > > This used to work before commit c3b1b1cbf0 as previously, ramfs would > ignore all options. But now, we get: > ramfs: bad mount option: size=10M > mount: mounting mdev on /dev failed: Invalid argument > > Another option might be to restore the previous behavior, where ramfs > simply ignored all unknown mount options ... which is what Hugh prefers. > > Signed-off-by: Mike Frysinger <vapier@gentoo.org> > Signed-off-by: Hugh Dickins <hugh.dickins@tiscali.co.uk> > Cc: stable@kernel.org > --- > > fs/ramfs/inode.c | 9 ++++++--- > 1 file changed, 6 insertions(+), 3 deletions(-) > > --- 2.6.30/fs/ramfs/inode.c 2009-06-10 04:05:27.000000000 +0100 > +++ linux/fs/ramfs/inode.c 2009-06-13 14:45:33.000000000 +0100 > @@ -202,9 +202,12 @@ static int ramfs_parse_options(char *dat > return -EINVAL; > opts->mode = option & S_IALLUGO; > break; > - default: > - printk(KERN_ERR "ramfs: bad mount option: %s\n", p); > - return -EINVAL; > + /* > + * We might like to report bad mount options here; > + * but traditionally ramfs has ignored all mount options, > + * and as it is used as a !CONFIG_SHMEM simple substitute > + * for tmpfs, better continue to ignore other mount options. > + */ > } > } >
Acked-by: Wu Fengguang <fengguang.wu@intel.com>
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