From: Jason Dillaman <dillaman@redhat.com>
Date: Mon, 19 Jan 2015 15:28:56 +0000 (-0500)
Subject: librbd: gracefully handle deleted/renamed pools
X-Git-Url: http://git-server-git.apps.pok.os.sepia.ceph.com/?a=commitdiff_plain;h=refs%2Fpull%2F3439%2Fhead;p=ceph.git

librbd: gracefully handle deleted/renamed pools

snap_unprotect and list_children both attempt to scan all
pools. If a pool is deleted or renamed during the scan,
the methods would previously return -ENOENT. Both methods
have been modified to more gracefully handle this condition.

Fixes: #10270, #10122
Backport: giant, firefly
Signed-off-by: Jason Dillaman <dillaman@redhat.com>
(cherry picked from commit 436923c68b77c900b7774fbef918c0d6e1614a36)
---

diff --git a/src/librbd/internal.cc b/src/librbd/internal.cc
index 627c11344dd..d7a428d4f02 100644
--- a/src/librbd/internal.cc
+++ b/src/librbd/internal.cc
@@ -425,7 +425,10 @@ namespace librbd {
 	 it != pools.end(); ++it) {
       IoCtx ioctx;
       r = rados.ioctx_create(it->c_str(), ioctx);
-      if (r < 0) {
+      if (r == -ENOENT) {
+        ldout(cct, 1) << "pool " << *it << " no longer exists" << dendl;
+        continue;
+      } else if (r < 0) {
         lderr(cct) << "Error accessing child image pool " << *it << dendl;
         return r;
       }
@@ -640,32 +643,46 @@ namespace librbd {
     parent_spec pspec(ictx->md_ctx.get_id(), ictx->id, snap_id);
     // search all pools for children depending on this snapshot
     Rados rados(ictx->md_ctx);
-    std::list<std::string> pools;
-    rados.pool_list(pools);
-    std::set<std::string> children;
-    for (std::list<std::string>::const_iterator it = pools.begin(); it != pools.end(); ++it) {
-      IoCtx pool_ioctx;
-      r = rados.ioctx_create(it->c_str(), pool_ioctx);
-      if (r < 0) {
-	lderr(ictx->cct) << "snap_unprotect: can't create ioctx for pool "
-			 << *it << dendl;
-	goto reprotect_and_return_err;
-      }
-      r = cls_client::get_children(&pool_ioctx, RBD_CHILDREN, pspec, children);
-      // key should not exist for this parent if there is no entry
-      if (((r < 0) && (r != -ENOENT))) {
-	lderr(ictx->cct) << "can't get children for pool " << *it << dendl;
-	goto reprotect_and_return_err;
-      }
-      // if we found a child, can't unprotect
-      if (r == 0) {
-	lderr(ictx->cct) << "snap_unprotect: can't unprotect; at least " 
-	  << children.size() << " child(ren) in pool " << it->c_str() << dendl;
-	r = -EBUSY;
-	goto reprotect_and_return_err;
+
+    // protect against pools being renamed/deleted
+    bool retry_pool_check;
+    do {
+      retry_pool_check = false;
+
+      std::list<std::string> pools;
+      rados.pool_list(pools);
+      for (std::list<std::string>::const_iterator it = pools.begin(); it != pools.end(); ++it) {
+	IoCtx pool_ioctx;
+	r = rados.ioctx_create(it->c_str(), pool_ioctx);
+        if (r == -ENOENT) {
+          ldout(ictx->cct, 1) << "pool " << *it << " no longer exists" << dendl;
+          retry_pool_check = true;
+          break;
+        } else if (r < 0) {
+          lderr(ictx->cct) << "snap_unprotect: can't create ioctx for pool "
+			   << *it << dendl;
+          goto reprotect_and_return_err;
+        }
+
+	std::set<std::string> children;
+	r = cls_client::get_children(&pool_ioctx, RBD_CHILDREN, pspec, children);
+	// key should not exist for this parent if there is no entry
+	if (((r < 0) && (r != -ENOENT))) {
+	  lderr(ictx->cct) << "can't get children for pool " << *it << dendl;
+	  goto reprotect_and_return_err;
+	}
+	// if we found a child, can't unprotect
+	if (r == 0) {
+	  lderr(ictx->cct) << "snap_unprotect: can't unprotect; at least "
+			   << children.size() << " child(ren) in pool "
+			   << it->c_str() << dendl;
+	  r = -EBUSY;
+	  goto reprotect_and_return_err;
+	}
+	pool_ioctx.close();	// last one out will self-destruct
       }
-      pool_ioctx.close();	// last one out will self-destruct
-    }
+    } while(retry_pool_check);
+
     // didn't find any child in any pool, go ahead with unprotect
     r = cls_client::set_protection_status(&ictx->md_ctx,
 					  ictx->header_oid,