From: Xiubo Li <xiubli@redhat.com>
Date: Mon, 8 Jul 2024 07:53:28 +0000 (+0800)
Subject: mds: avoid acquiring the wrlock twice for a single request
X-Git-Tag: v20.0.0~314^2
X-Git-Url: http://git-server-git.apps.pok.os.sepia.ceph.com/?a=commitdiff_plain;h=276b81a55d391b52f9772fc76b86b845eb3854a6;p=ceph.git

mds: avoid acquiring the wrlock twice for a single request

In case the current request has lock cache attached and then the
lock cache must have already acquired the wrlock of filelock. So
currently the path_traverse() will acquire the wrlock twice and
possibly caused deadlock by itself.

Fixes: https://tracker.ceph.com/issues/65607
Signed-off-by: Xiubo Li <xiubli@redhat.com>
Signed-off-by: Sunnatillo <sunnat.samadov@est.tech>
---

diff --git a/src/mds/MDCache.cc b/src/mds/MDCache.cc
index 3af0d8c6b1ec..cbe7c94bf099 100644
--- a/src/mds/MDCache.cc
+++ b/src/mds/MDCache.cc
@@ -8515,8 +8515,11 @@ int MDCache::path_traverse(const MDRequestRef& mdr, MDSContextFactory& cf,
 	  lov.add_xlock(&dn->lock);
 	} else {
 	  // force client to flush async dir operation if necessary
-	  if (cur->filelock.is_cached())
+	  if (cur->filelock.is_cached() &&
+	      !(mdr->lock_cache &&
+		static_cast<const MutationImpl*>(mdr->lock_cache)->is_wrlocked(&cur->filelock))) {
 	    lov.add_wrlock(&cur->filelock);
+	  }
 	  lov.add_rdlock(&dn->lock);
 	}
 	if (!mds->locker->acquire_locks(mdr, lov)) {
@@ -8635,8 +8638,11 @@ int MDCache::path_traverse(const MDRequestRef& mdr, MDSContextFactory& cf,
 		lov.add_xlock(&dn->lock);
 	      } else {
 		// force client to flush async dir operation if necessary
-		if (cur->filelock.is_cached())
+		if (cur->filelock.is_cached() &&
+		    !(mdr->lock_cache &&
+		      static_cast<const MutationImpl*>(mdr->lock_cache)->is_wrlocked(&cur->filelock))) {
 		  lov.add_wrlock(&cur->filelock);
+		}
 		lov.add_rdlock(&dn->lock);
 	      }
 	      if (!mds->locker->acquire_locks(mdr, lov)) {
diff --git a/src/mds/MDSRank.cc b/src/mds/MDSRank.cc
index 9448e63749f1..b1e0d987194f 100644
--- a/src/mds/MDSRank.cc
+++ b/src/mds/MDSRank.cc
@@ -4041,6 +4041,7 @@ const char** MDSRankDispatcher::get_tracked_conf_keys() const
     "clog_to_syslog_level", \
     "fsid", \
     "host", \
+    "mds_allow_async_dirops", \
     "mds_alternate_name_max", \
     "mds_bal_export_pin", \
     "mds_bal_fragment_dirs", \
@@ -4116,8 +4117,7 @@ const char** MDSRankDispatcher::get_tracked_conf_keys() const
     "mds_session_cap_acquisition_throttle", \
     "mds_session_max_caps_throttle_ratio", \
     "mds_session_metadata_threshold", \
-    "mds_symlink_recovery", \
-    "mds_allow_async_dirops"
+    "mds_symlink_recovery"
 
   constexpr bool is_sorted = [] () constexpr {
     constexpr auto arr = std::to_array<std::string_view>({KEYS});