1 files changed, 17 insertions, 10 deletions

diff --git a/fs/ceph/caps.c b/fs/ceph/caps.c
index e7af6479c9bc..92643b828c50 100644
--- a/fs/ceph/caps.c
+++ b/fs/ceph/caps.c
@@ -1973,8 +1973,7 @@ retry_locked:
                         goto ack;
 
                 /* things we might delay */
-                if ((cap->issued & ~retain) == 0 &&
-                    cap->mds_wanted == want)
+                if ((cap->issued & ~retain) == 0)
                         continue;     /* nope, all good */
 
                 if (no_delay)
@@ -3051,7 +3050,8 @@ static void handle_cap_grant(struct inode *inode,
         int used, wanted, dirty;
         u64 size = le64_to_cpu(grant->size);
         u64 max_size = le64_to_cpu(grant->max_size);
-        int check_caps = 0;
+        unsigned char check_caps = 0;
+        bool was_stale = cap->cap_gen < session->s_cap_gen;
         bool wake = false;
         bool writeback = false;
         bool queue_trunc = false;
@@ -3203,13 +3203,20 @@ static void handle_cap_grant(struct inode *inode,
              ceph_cap_string(wanted),
              ceph_cap_string(used),
              ceph_cap_string(dirty));
-        if (wanted != le32_to_cpu(grant->wanted)) {
-                dout("mds wanted %s -> %s\n",
-                     ceph_cap_string(le32_to_cpu(grant->wanted)),
-                     ceph_cap_string(wanted));
-                /* imported cap may not have correct mds_wanted */
-                if (le32_to_cpu(grant->op) == CEPH_CAP_OP_IMPORT)
-                        check_caps = 1;
+
+        if ((was_stale || le32_to_cpu(grant->op) == CEPH_CAP_OP_IMPORT) &&
+            (wanted & ~(cap->mds_wanted | newcaps))) {
+                /*
+                 * If mds is importing cap, prior cap messages that update
+                 * 'wanted' may get dropped by mds (migrate seq mismatch).
+                 *
+                 * We don't send cap message to update 'wanted' if what we
+                 * want are already issued. If mds revokes caps, cap message
+                 * that releases caps also tells mds what we want. But if
+                 * caps got revoked by mds forcedly (session stale). We may
+                 * haven't told mds what we want.
+                 */
+                check_caps = 1;
         }
 
         /* revocation, grant, or no-op? */