Re: [RFC PATCH] ceph: initialize superblock s_time_gran to 1
From: Sage Weil
Date: Thu Jun 27 2019 - 11:44:36 EST
On Thu, 27 Jun 2019, Jeff Layton wrote:
> On Thu, 2019-06-27 at 14:51 +0100, Luis Henriques wrote:
> > Having granularity set to 1us results in having inode timestamps with a
> > accurancy different from the fuse client (i.e. atime, ctime and mtime will
> > always end with '000'). This patch normalizes this behaviour and sets the
> > granularity to 1.
> >
> > Signed-off-by: Luis Henriques <lhenriques@xxxxxxxx>
> > ---
> > fs/ceph/super.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > Hi!
> >
> > As far as I could see there are no other side-effects of changing
> > s_time_gran but I'm really not sure why it was initially set to 1000 in
> > the first place so I may be missing something.
> >
> > diff --git a/fs/ceph/super.c b/fs/ceph/super.c
> > index d57fa60dcd43..35dd75bc9cd0 100644
> > --- a/fs/ceph/super.c
> > +++ b/fs/ceph/super.c
> > @@ -980,7 +980,7 @@ static int ceph_set_super(struct super_block *s, void *data)
> > s->s_d_op = &ceph_dentry_ops;
> > s->s_export_op = &ceph_export_ops;
> >
> > - s->s_time_gran = 1000; /* 1000 ns == 1 us */
> > + s->s_time_gran = 1;
> >
> > ret = set_anon_super(s, NULL); /* what is that second arg for? */
> > if (ret != 0)
>
>
> Looks like it was set that way since the client code was originally
> merged. Was this an earlier limitation of ceph that is no longer
> applicable?
>
> In any case, I see no need at all to keep this at 1000, so:
As long as the encoded on-write time value is at ns resolution, I
agree! No recollection of why I did this :(
Reviewed-by: Sage Weil <sage@xxxxxxxxxx>