From: Josh Durgin <josh.durgin@inktank.com>
Date: Sun, 30 Dec 2012 04:35:15 +0000 (-0800)
Subject: librbd: fix race between unprotect and clone
X-Git-Tag: v0.56~1^2~1
X-Git-Url: http://git-server-git.apps.pok.os.sepia.ceph.com/?a=commitdiff_plain;h=d0a14d110db7ce13342af0995d7eb4d5e7798653;p=ceph.git

librbd: fix race between unprotect and clone

Clone needs to actually re-read the header to make sure the image is
still protected before returning. Additionally, it needs to consider
the image protected *only* if the protection status is protected -
unprotecting does not count. I thought I'd already fixed this, but
can't find the commit.

Signed-off-by: Josh Durgin <josh.durgin@inktank.com>
---

diff --git a/src/librbd/ImageCtx.cc b/src/librbd/ImageCtx.cc
index fb9212e187ed..80f19d235501 100644
--- a/src/librbd/ImageCtx.cc
+++ b/src/librbd/ImageCtx.cc
@@ -327,7 +327,7 @@ namespace librbd {
     map<string, SnapInfo>::const_iterator it = snaps_by_name.find(in_snap_name);
     if (it != snaps_by_name.end()) {
       *is_protected =
-	(it->second.protection_status != RBD_PROTECTION_STATUS_UNPROTECTED);
+	(it->second.protection_status == RBD_PROTECTION_STATUS_PROTECTED);
       return 0;
     }
     return -ENOENT;
diff --git a/src/librbd/internal.cc b/src/librbd/internal.cc
index 53ce19c65fc6..ee8966cb40e2 100644
--- a/src/librbd/internal.cc
+++ b/src/librbd/internal.cc
@@ -963,10 +963,15 @@ reprotect_and_return_err:
       goto err_close_child;
     }
 
-    p_imctx->snap_lock.Lock();
-    r = p_imctx->is_snap_protected(p_imctx->snap_name, &snap_protected);
-    p_imctx->snap_lock.Unlock();
+    p_imctx->md_lock.Lock();
+    r = ictx_refresh(p_imctx);
+    p_imctx->md_lock.Unlock();
 
+    if (r == 0) {
+      p_imctx->snap_lock.Lock();
+      r = p_imctx->is_snap_protected(p_imctx->snap_name, &snap_protected);
+      p_imctx->snap_lock.Unlock();
+    }
     if (r < 0 || !snap_protected) {
       // we lost the race with unprotect
       r = -EINVAL;