mon: refine check_remove_tier checks

Fixes: #11504
Signed-off-by: John Spray <john.spray@redhat.com>
(cherry picked from commit a50c8f1f2ad8845c7f77110868f9376f2d1ff883)

diff --git a/src/mon/OSDMonitor.cc b/src/mon/OSDMonitor.cc
index cdbb6c752e9e2eafac585fc6c394602fe4ed2072..2f08e41bdf632756080e8ba5a6ee44b1e9b51dac 100644 (file)
--- a/src/mon/OSDMonitor.cc
+++ b/src/mon/OSDMonitor.cc
@@ -6229,7 +6229,7 @@ done:
     const pg_pool_t *tp = osdmap.get_pg_pool(tierpool_id);
     assert(tp);
 
-    if (!_check_remove_tier(pool_id, p, &err, &ss)) {
+    if (!_check_remove_tier(pool_id, p, tp, &err, &ss)) {
       goto reply;
     }
 
@@ -6334,7 +6334,7 @@ done:
       goto reply;
     }
 
-    if (!_check_remove_tier(pool_id, p, &err, &ss)) {
+    if (!_check_remove_tier(pool_id, p, NULL, &err, &ss)) {
       goto reply;
     }
 
@@ -7000,17 +7000,29 @@ bool OSDMonitor::_check_become_tier(
  */
 bool OSDMonitor::_check_remove_tier(
     const int64_t base_pool_id, const pg_pool_t *base_pool,
+    const pg_pool_t *tier_pool,
     int *err, ostream *ss) const
 {
   const std::string &base_pool_name = osdmap.get_pool_name(base_pool_id);
 
-  // If the pool is in use by CephFS, then refuse to remove its
-  // tier
+  // Apply CephFS-specific checks
   const MDSMap &pending_mdsmap = mon->mdsmon()->pending_mdsmap;
   if (pending_mdsmap.pool_in_use(base_pool_id)) {
-    *ss << "pool '" << base_pool_name << "' is in use by CephFS via its tier";
-    *err = -EBUSY;
-    return false;
+    if (base_pool->type != pg_pool_t::TYPE_REPLICATED) {
+      // If the underlying pool is erasure coded, we can't permit the
+      // removal of the replicated tier that CephFS relies on to access it
+      *ss << "pool '" << base_pool_name << "' is in use by CephFS via its tier";
+      *err = -EBUSY;
+      return false;
+    }
+
+    if (tier_pool && tier_pool->cache_mode == pg_pool_t::CACHEMODE_WRITEBACK) {
+      *ss << "pool '" << base_pool_name << "' is in use by CephFS, and this "
+             "tier is still in use as a writeback cache.  Change the cache "
+             "mode and flush the cache before removing it";
+      *err = -EBUSY;
+      return false;
+    }
   }
 
   *err = 0;

diff --git a/src/mon/OSDMonitor.h b/src/mon/OSDMonitor.h
index 414bf0824102898e12f03102896ff76b7d894658..d0ecce9dac5d4b74ad3ed6510ae4d08e12107dc2 100644 (file)
--- a/src/mon/OSDMonitor.h
+++ b/src/mon/OSDMonitor.h
@@ -259,7 +259,7 @@ private:
       int64_t base_pool_id, const pg_pool_t *base_pool,
       int *err, ostream *ss) const;
   bool _check_remove_tier(
-      int64_t base_pool_id, const pg_pool_t *base_pool,
+      int64_t base_pool_id, const pg_pool_t *base_pool, const pg_pool_t *tier_pool,
       int *err, ostream *ss) const;
 
   int _prepare_remove_pool(int64_t pool, ostream *ss);