| Message ID | 1365606338-12278-1-git-send-email-sam.lang@inktank.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
Yup, that is a change to not use entropy and to short-circuit if we only have one choice. And this function has no side effects so it just needs to return an int. Reviewed-by: Greg Farnum <greg@inktank.com> Software Engineer #42 @ http://inktank.com | http://ceph.com On Wed, Apr 10, 2013 at 8:05 AM, Sam Lang <samlang@gmail.com> wrote: > We don't need to use up entropy to choose an mds, > so use prandom_u32() to get a pseudo-random number. > > Also, we don't need to choose a random mds if only > one mds is available, so add special casing for the > common case. > > Fixes http://tracker.ceph.com/issues/3579 > > Signed-off-by: Sam Lang <sam.lang@inktank.com> > --- > fs/ceph/mdsmap.c | 8 +++++--- > 1 file changed, 5 insertions(+), 3 deletions(-) > > diff --git a/fs/ceph/mdsmap.c b/fs/ceph/mdsmap.c > index 0d3c924..9278dec 100644 > --- a/fs/ceph/mdsmap.c > +++ b/fs/ceph/mdsmap.c > @@ -20,7 +20,10 @@ int ceph_mdsmap_get_random_mds(struct ceph_mdsmap *m) > { > int n = 0; > int i; > - char r; > + > + /* special case for one mds */ > + if (1 == m->m_max_mds && m->m_info[0].state > 0) > + return 0; > > /* count */ > for (i = 0; i < m->m_max_mds; i++) > @@ -30,8 +33,7 @@ int ceph_mdsmap_get_random_mds(struct ceph_mdsmap *m) > return -1; > > /* pick */ > - get_random_bytes(&r, 1); > - n = r % n; > + n = prandom_u32() % n; > i = 0; > for (i = 0; n > 0; i++, n--) > while (m->m_info[i].state <= 0) > -- > 1.7.10.4 > > -- > To unsubscribe from this list: send the line "unsubscribe ceph-devel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe ceph-devel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/fs/ceph/mdsmap.c b/fs/ceph/mdsmap.c index 0d3c924..9278dec 100644 --- a/fs/ceph/mdsmap.c +++ b/fs/ceph/mdsmap.c @@ -20,7 +20,10 @@ int ceph_mdsmap_get_random_mds(struct ceph_mdsmap *m) { int n = 0; int i; - char r; + + /* special case for one mds */ + if (1 == m->m_max_mds && m->m_info[0].state > 0) + return 0; /* count */ for (i = 0; i < m->m_max_mds; i++) @@ -30,8 +33,7 @@ int ceph_mdsmap_get_random_mds(struct ceph_mdsmap *m) return -1; /* pick */ - get_random_bytes(&r, 1); - n = r % n; + n = prandom_u32() % n; i = 0; for (i = 0; n > 0; i++, n--) while (m->m_info[i].state <= 0)
We don't need to use up entropy to choose an mds, so use prandom_u32() to get a pseudo-random number. Also, we don't need to choose a random mds if only one mds is available, so add special casing for the common case. Fixes http://tracker.ceph.com/issues/3579 Signed-off-by: Sam Lang <sam.lang@inktank.com> --- fs/ceph/mdsmap.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-)