On Mon, 12 Jul 2010, Aneesh Kumar K. V wrote:
> On Mon, 12 Jul 2010 12:05:43 +0530, "Aneesh Kumar K.V" <aneesh.kumar@xxxxxxxxxxxxxxxxxx> wrote:
> > We add a per superblock uuid field. File systems should
> > update the uuid in the fill_super callback
> >
> > Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxxxxxxx>
> > ---
> > fs/namespace.c | 3 +++
> > include/linux/fs.h | 1 +
> > 2 files changed, 4 insertions(+), 0 deletions(-)
> >
> > diff --git a/fs/namespace.c b/fs/namespace.c
> > index 88058de..5dbdbd6 100644
> > --- a/fs/namespace.c
> > +++ b/fs/namespace.c
> > @@ -871,6 +871,9 @@ static int show_mountinfo(struct seq_file *m, void *v)
> > if (IS_MNT_UNBINDABLE(mnt))
> > seq_puts(m, " unbindable");
> >
> > + /* print the uuid */
> > + seq_printf(m, " uuid:%pU", mnt->mnt_sb->s_uuid);
> > +
> > /* Filesystem specific data */
> > seq_puts(m, " - ");
> > show_type(m, sb);
> > diff --git a/include/linux/fs.h b/include/linux/fs.h
> > index 3103c39..5f43472 100644
> > --- a/include/linux/fs.h
> > +++ b/include/linux/fs.h
> > @@ -1367,6 +1367,7 @@ struct super_block {
> > wait_queue_head_t s_wait_unfrozen;
> >
> > char s_id[32]; /* Informational name */
> > + u8 s_uuid[16]; /* UUID */
> >
> > void *s_fs_info; /* Filesystem private info */
> > fmode_t s_mode;
>
> since it is an optional tag is it ok to do the below patch ? or does
> optional is a way to introduce changes across kernel version and
> each line is suppose to have new added fields ?.
Tagged fields are optional, so yes, the patch is OK.
> Is there a userspace
> tool that use /proc/<pid>/mouninfo ?
libmount from recent enough util-linux is using mountinfo. So
mount(8) should be using it, as well as some other utilities in
util-linux.
Thanks,
Miklos
>
> diff --git a/fs/namespace.c b/fs/namespace.c
> index 5dbdbd6..7542959 100644
> --- a/fs/namespace.c
> +++ b/fs/namespace.c
> @@ -833,6 +833,16 @@ const struct seq_operations mounts_op = {
> .show = show_vfsmnt
> };
>
> +static int uuid_is_nil(u8 *uuid)
> +{
> + int i;
> + u8 *cp = (u8 *)uuid;
> +
> + for (i = 0; i < 16; i++)
> + if (*cp++) return 0; /* not nil */
> + return 1; /* is nil */
> +}
> +
> static int show_mountinfo(struct seq_file *m, void *v)
> {
> struct proc_mounts *p = m->private;
> @@ -871,8 +881,9 @@ static int show_mountinfo(struct seq_file *m, void *v)
> if (IS_MNT_UNBINDABLE(mnt))
> seq_puts(m, " unbindable");
>
> + if (!uuid_is_nil(mnt->mnt_sb->s_uuid))
> /* print the uuid */
> - seq_printf(m, " uuid:%pU", mnt->mnt_sb->s_uuid);
> + seq_printf(m, " uuid:%pU", mnt->mnt_sb->s_uuid);
>
> /* Filesystem specific data */
> seq_puts(m, " - ");
>
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