[PATCH] vfs: fix mounting a filesystem with i_version

[zohar@linux.vnet.ibm.com (Mimi Zohar)]

On Sun, 2017-10-08 at 01:58 -0700, Christoph Hellwig wrote:
> On Sun, Oct 08, 2017 at 12:28:21AM -0400, Mimi Zohar wrote:
> > The mount i_version flag is not enabled in the new sb_flags.  This patch
> > adds the missing SB_I_VERSION flag.
> > 
> > Fixes: e462ec5 "VFS: Differentiate mount flags (MS_*) from internal
> >        superblock flags"
> > Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
> > ---
> >  fs/namespace.c | 3 ++-
> >  1 file changed, 2 insertions(+), 1 deletion(-)
> > 
> > diff --git a/fs/namespace.c b/fs/namespace.c
> > index 3b601f115b6c..d18deb4c410b 100644
> > --- a/fs/namespace.c
> > +++ b/fs/namespace.c
> > @@ -2825,7 +2825,8 @@ long do_mount(const char *dev_name, const char __user *dir_name,
> >  			    SB_MANDLOCK |
> >  			    SB_DIRSYNC |
> >  			    SB_SILENT |
> > -			    SB_POSIXACL);
> > +			    SB_POSIXACL |
> > +			    SB_I_VERSION);
> 
> The problem is that the whole masking there is a piece of crap.
> 
> It assumes that MS_* and SB_* flags have the same numeric values,
> which is bound to create a major problem rather sooner than later.

According to the original commit, separating them is just the first
step. ?This patch fixes that first step so that filesystems can be
mounted with i_version.

Mimi

> What we need is a separate __bitwise type for SB_*, translated them
> here and treat them as a separate namespaces.
> 

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