9p fid refcount: add p9_fid_get/put wrappers

[sfrench/cifs-2.6.git] / include / net / 9p / client.h

diff --git a/include/net/9p/client.h b/include/net/9p/client.h
index ec1d1706f43c03fad268f7a92f47b2abb7170374..eabb53992350c521d523b0ff87ac471ec059125f 100644 (file)
--- a/include/net/9p/client.h
+++ b/include/net/9p/client.h
@@ -237,6 +237,34 @@ static inline int p9_req_try_get(struct p9_req_t *r)
 
 int p9_req_put(struct p9_req_t *r);
 
+/* fid reference counting helpers:
+ *  - fids used for any length of time should always be referenced through
+ *    p9_fid_get(), and released with p9_fid_put()
+ *  - v9fs_fid_lookup() or similar will automatically call get for you
+ *    and also require a put
+ *  - the *_fid_add() helpers will stash the fid in the inode,
+ *    at which point it is the responsibility of evict_inode()
+ *    to call the put
+ *  - the last put will automatically send a clunk to the server
+ */
+static inline struct p9_fid *p9_fid_get(struct p9_fid *fid)
+{
+       refcount_inc(&fid->count);
+
+       return fid;
+}
+
+static inline int p9_fid_put(struct p9_fid *fid)
+{
+       if (!fid || IS_ERR(fid))
+               return 0;
+
+       if (!refcount_dec_and_test(&fid->count))
+               return 0;
+
+       return p9_client_clunk(fid);
+}
+
 void p9_client_cb(struct p9_client *c, struct p9_req_t *req, int status);
 
 int p9_parse_header(struct p9_fcall *pdu, int32_t *size, int8_t *type,