ceph: avoid calling ceph_renew_caps() infinitely

__ceph_caps_mds_wanted() ignores caps from stale session. So the
return value of __ceph_caps_mds_wanted() can keep the same across
ceph_renew_caps(). This causes try_get_cap_refs() to keep calling
ceph_renew_caps(). The fix is ignore the session valid check for
the try_get_cap_refs() case. If session is stale, just let the
caps requester sleep.
Signed-off-by: Yan, Zheng <zyan@redhat.com>

fs/ceph/caps.c

@@ -867,7 +867,7 @@ int __ceph_caps_file_wanted(struct ceph_inode_info *ci)
 /*
  * Return caps we have registered with the MDS(s) as 'wanted'.
  */
-int __ceph_caps_mds_wanted(struct ceph_inode_info *ci)
+int __ceph_caps_mds_wanted(struct ceph_inode_info *ci, bool check)
 {
 	struct ceph_cap *cap;
 	struct rb_node *p;
@@ -875,7 +875,7 @@ int __ceph_caps_mds_wanted(struct ceph_inode_info *ci)
 
 	for (p = rb_first(&ci->i_caps); p; p = rb_next(p)) {
 		cap = rb_entry(p, struct ceph_cap, ci_node);
-		if (!__cap_is_valid(cap))
+		if (check && !__cap_is_valid(cap))
 			continue;
 		if (cap == ci->i_auth_cap)
 			mds_wanted |= cap->mds_wanted;
@@ -2491,7 +2491,7 @@ static int try_get_cap_refs(struct ceph_inode_info *ci, int need, int want,
 				ret = 1;
 				goto out_unlock;
 			}
-			mds_wanted = __ceph_caps_mds_wanted(ci);
+			mds_wanted = __ceph_caps_mds_wanted(ci, false);
 			if (need & ~(mds_wanted & need)) {
 				dout("get_cap_refs %p caps were dropped"
 				     " (session killed?)\n", inode);

fs/ceph/file.c

@@ -283,7 +283,7 @@ int ceph_open(struct inode *inode, struct file *file)
 	spin_lock(&ci->i_ceph_lock);
 	if (__ceph_is_any_real_caps(ci) &&
 	    (((fmode & CEPH_FILE_MODE_WR) == 0) || ci->i_auth_cap)) {
-		int mds_wanted = __ceph_caps_mds_wanted(ci);
+		int mds_wanted = __ceph_caps_mds_wanted(ci, true);
 		int issued = __ceph_caps_issued(ci, NULL);
 
 		dout("open %p fmode %d want %s issued %s using existing\n",

fs/ceph/super.h

@@ -602,7 +602,7 @@ static inline int __ceph_caps_wanted(struct ceph_inode_info *ci)
 }
 
 /* what the mds thinks we want */
-extern int __ceph_caps_mds_wanted(struct ceph_inode_info *ci);
+extern int __ceph_caps_mds_wanted(struct ceph_inode_info *ci, bool check);
 
 extern void ceph_caps_init(struct ceph_mds_client *mdsc);
 extern void ceph_caps_finalize(struct ceph_mds_client *mdsc);