diff --git a/fs/ceph/caps.c b/fs/ceph/caps.c
index 539a24965afe..bcb04c6cb92c 100644
--- a/fs/ceph/caps.c
+++ b/fs/ceph/caps.c
@@ -987,6 +987,27 @@ int __ceph_caps_revoking_other(struct ceph_inode_info *ci,
 	return 0;
 }
 
+/*
+ * Return true if any cap of this inode holds caps which the MDS has
+ * revoked, but which we have not released yet.
+ */
+static bool __ceph_is_any_revoking(const struct ceph_inode_info *ci)
+{
+	const struct rb_node *p;
+
+	lockdep_assert_held(&ci->i_ceph_lock);
+
+	for (p = rb_first(&ci->i_caps); p; p = rb_next(p)) {
+		const struct ceph_cap *cap =
+			rb_entry(p, struct ceph_cap, ci_node);
+
+		if (cap->implemented & ~cap->issued)
+			return true;
+	}
+
+	return false;
+}
+
 int __ceph_caps_used(struct ceph_inode_info *ci)
 {
 	int used = 0;
@@ -1431,6 +1452,9 @@ static void __prep_cap(struct cap_msg_args *arg, struct ceph_inode_info *ci,
 	cap->implemented &= cap->issued | used;
 	cap->mds_wanted = want;
 
+	if ((ci->i_ceph_flags & CEPH_I_FLUSH_FORCE) != 0 && !__ceph_is_any_revoking(ci))
+		clear_bit(CEPH_I_FLUSH_FORCE_BIT, &ci->i_ceph_flags);
+
 	arg->session = cap->session;
 	arg->ino = ceph_vino(inode).ino;
 	arg->cid = cap->cap_id;
@@ -2048,6 +2072,14 @@ void ceph_check_caps(struct ceph_inode_info *ci, int flags)
 
 	if (ci->i_ceph_flags & CEPH_I_FLUSH)
 		flags |= CHECK_CAPS_FLUSH;
+	/*
+	 * A revoke whose response was deferred (see handle_cap_grant()) must
+	 * still be acknowledged.  Replay the forced flush here so that even a
+	 * check triggered by writeback/invalidation completion sends a cap
+	 * message to the MDS.
+	 */
+	if (ci->i_ceph_flags & CEPH_I_FLUSH_FORCE)
+		flags |= CHECK_CAPS_FLUSH_FORCE;
 retry:
 	/* Caps wanted by virtue of active open files. */
 	file_wanted = __ceph_caps_file_wanted(ci);
@@ -3774,13 +3806,30 @@ static void handle_cap_grant(struct inode *inode,
 	BUG_ON(cap->issued & ~cap->implemented);
 
 	/* don't let check_caps skip sending a response to MDS for revoke msgs */
-	if (!revoke_wait && le32_to_cpu(grant->op) == CEPH_CAP_OP_REVOKE) {
-		cap->mds_wanted = 0;
-		flags |= CHECK_CAPS_FLUSH_FORCE;
-		if (cap == ci->i_auth_cap)
-			check_caps = 1; /* check auth cap only */
-		else
-			check_caps = 2; /* check all caps */
+	if (le32_to_cpu(grant->op) == CEPH_CAP_OP_REVOKE) {
+		if (revoke_wait) {
+			/*
+			 * We can't ack the revoke yet: the response is deferred
+			 * until the writeback or cache invalidation queued above
+			 * completes.  Set the CEPH_I_FLUSH_FORCE flag to remember
+			 * that a forced cap message is owed so that deferred
+			 * completion (ceph_put_wrbuffer_cap_refs() or the
+			 * invalidate worker, both of which call ceph_check_caps())
+			 * actually sends one, even if by then the revoked caps look
+			 * unused, the inode is retaining caps, or the MDS has
+			 * re-granted them.  Without this, the cap message is never
+			 * sent and the MDS hangs ("isn't responding to
+			 * mclientcaps(revoke)").
+			 */
+			set_bit(CEPH_I_FLUSH_FORCE_BIT, &ci->i_ceph_flags);
+		} else {
+			cap->mds_wanted = 0;
+			flags |= CHECK_CAPS_FLUSH_FORCE;
+			if (cap == ci->i_auth_cap)
+				check_caps = 1; /* check auth cap only */
+			else
+				check_caps = 2; /* check all caps */
+		}
 	}
 
 	if (extra_info->inline_version > 0 &&
diff --git a/fs/ceph/super.h b/fs/ceph/super.h
index 0020ccd0f974..72d4e30304dc 100644
--- a/fs/ceph/super.h
+++ b/fs/ceph/super.h
@@ -709,6 +709,10 @@ static inline struct inode *ceph_find_inode(struct super_block *sb,
 #define CEPH_I_ASYNC_CREATE_BIT		(12) /* async create in flight for this */
 #define CEPH_I_SHUTDOWN_BIT		(13) /* inode is no longer usable */
 #define CEPH_I_ASYNC_CHECK_CAPS_BIT	(14) /* check caps after async creating finishes */
+#define CEPH_I_FLUSH_FORCE_BIT		(15) /* a revoke's response was deferred;
+					      * force a cap message to the MDS once
+					      * the deferred work completes
+					      */
 
 #define CEPH_I_DIR_ORDERED		(1 << CEPH_I_DIR_ORDERED_BIT)
 #define CEPH_I_FLUSH			(1 << CEPH_I_FLUSH_BIT)
@@ -721,6 +725,7 @@ static inline struct inode *ceph_find_inode(struct super_block *sb,
 #define CEPH_I_ODIRECT			(1 << CEPH_I_ODIRECT_BIT)
 #define CEPH_I_ASYNC_CREATE		(1 << CEPH_I_ASYNC_CREATE_BIT)
 #define CEPH_I_SHUTDOWN			(1 << CEPH_I_SHUTDOWN_BIT)
+#define CEPH_I_FLUSH_FORCE		(1 << CEPH_I_FLUSH_FORCE_BIT)
 
 /*
  * Masks of ceph inode work.