lkml.org 
[lkml]   [2017]   [Oct]   [3]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH 4.13 062/110] libceph: dont allow bidirectional swap of pg-upmap-items
Date
4.13-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Ilya Dryomov <idryomov@gmail.com>

commit 29a0cfbf91ba997591535a4f7246835ce8328141 upstream.

This reverts most of commit f53b7665c8ce ("libceph: upmap semantic
changes").

We need to prevent duplicates in the final result. For example, we
can currently take

[1,2,3] and apply [(1,2)] and get [2,2,3]

or

[1,2,3] and apply [(3,2)] and get [1,2,2]

The rest of the system is not prepared to handle duplicates in the
result set like this.

The reverted piece was intended to allow

[1,2,3] and [(1,2),(2,1)] to get [2,1,3]

to reorder primaries. First, this bidirectional swap is hard to
implement in a way that also prevents dups. For example, [1,2,3] and
[(1,4),(2,3),(3,4)] would give [4,3,4] but would we just drop the last
step we'd have [4,3,3] which is also invalid, etc. Simpler to just not
handle bidirectional swaps. In practice, they are not needed: if you
just want to choose a different primary then use primary_affinity, or
pg_upmap (not pg_upmap_items).

Link: http://tracker.ceph.com/issues/21410
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Reviewed-by: Sage Weil <sage@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
net/ceph/osdmap.c | 33 ++++++++++++++++++++++++---------
1 file changed, 24 insertions(+), 9 deletions(-)

--- a/net/ceph/osdmap.c
+++ b/net/ceph/osdmap.c
@@ -2445,19 +2445,34 @@ static void apply_upmap(struct ceph_osdm

pg = lookup_pg_mapping(&osdmap->pg_upmap_items, pgid);
if (pg) {
- for (i = 0; i < raw->size; i++) {
- for (j = 0; j < pg->pg_upmap_items.len; j++) {
- int from = pg->pg_upmap_items.from_to[j][0];
- int to = pg->pg_upmap_items.from_to[j][1];
+ /*
+ * Note: this approach does not allow a bidirectional swap,
+ * e.g., [[1,2],[2,1]] applied to [0,1,2] -> [0,2,1].
+ */
+ for (i = 0; i < pg->pg_upmap_items.len; i++) {
+ int from = pg->pg_upmap_items.from_to[i][0];
+ int to = pg->pg_upmap_items.from_to[i][1];
+ int pos = -1;
+ bool exists = false;

- if (from == raw->osds[i]) {
- if (!(to != CRUSH_ITEM_NONE &&
- to < osdmap->max_osd &&
- osdmap->osd_weight[to] == 0))
- raw->osds[i] = to;
+ /* make sure replacement doesn't already appear */
+ for (j = 0; j < raw->size; j++) {
+ int osd = raw->osds[j];
+
+ if (osd == to) {
+ exists = true;
break;
}
+ /* ignore mapping if target is marked out */
+ if (osd == from && pos < 0 &&
+ !(to != CRUSH_ITEM_NONE &&
+ to < osdmap->max_osd &&
+ osdmap->osd_weight[to] == 0)) {
+ pos = j;
+ }
}
+ if (!exists && pos >= 0)
+ raw->osds[pos] = to;
}
}
}

\
 
 \ /
  Last update: 2017-10-03 14:47    [W:0.449 / U:0.152 seconds]
©2003-2017 Jasper Spaans. hosted at Digital OceanAdvertise on this site