From: ethanwu <ethanwu@synology.com>
Date: Mon, 15 Sep 2025 08:36:54 +0000 (+0800)
Subject: osd/SnapMapper: fix SnapMapper::Scrubber pg shard parsing
X-Git-Url: http://git.apps.os.sepia.ceph.com/?a=commitdiff_plain;h=9dda7afd8d851f1424e4a819aaf0d41e29fb749f;p=ceph.git

osd/SnapMapper: fix SnapMapper::Scrubber pg shard parsing

Note: the following only applies to EC pools as replicated pools have no
shard in the SNA_ keys.

Note: The Scrubber is only responsible for clearing entries that (_for
some anomalous reason_) remained in the store and should have been
purged.

SnapMapper::Scrubber::_parse_m is using the wrong key format (See:
napMapper::get_prefix) to obtain the pg shard.
While the correct format in EC pgs is:

<MAPPING_PREFIX><pool>_<snapid>_.<shardid>_<hobject_t::to_str()>
*******************************^

Or in replicated case:

<MAPPING_PREFIX><pool>_<snapid>_<hobject_t::to_str()>
*******************************^

The Scrubber is parsing the key a `.` instead of `_`.

---

`sscanf` should return the 3 if the third parameter (shard) was
successfully parsed.
Otherwise, we assume no shard is present in this key.

Fixes: https://tracker.ceph.com/issues/73018
Signed-off-by: ethanwu <ethanwu@synology.com>
---

diff --git a/src/osd/SnapMapper.cc b/src/osd/SnapMapper.cc
index 2f22ea9c9ee17..d9d27dfabc692 100644
--- a/src/osd/SnapMapper.cc
+++ b/src/osd/SnapMapper.cc
@@ -976,8 +976,8 @@ bool SnapMapper::Scrubber::_parse_m(
   {
     unsigned long long p, s;
     long sh;
-    int r = sscanf(key.data(), "SNA_%lld_%llx.%lx", &p, &s, &sh);
-    if (r != 1) {
+    int r = sscanf(key.data(), "SNA_%lld_%llx_.%lx", &p, &s, &sh);
+    if (r != 3) {
       shard = shard_id_t::NO_SHARD;
     } else {
       shard = shard_id_t(sh);