nfsd41: sessionid hashing

Simple sessionid hashing using its monotonically increasing sequence number.

Locking considerations:
sessionid_hashtbl access is controlled by the sessionid_lock spin lock.
It must be taken for insert, delete, and lookup.
nfsd4_sequence looks up the session id and if the session is found,
it calls nfsd4_get_session (still under the sessionid_lock).
nfsd4_destroy_session calls nfsd4_put_session after unhashing
it, so when the session's kref reaches zero it's going to get freed.

Signed-off-by: Benny Halevy <bhalevy@panasas.com>
[we don't use a prime for sessionid hash table size]
[use sessionid_lock spin lock]
Signed-off-by: Benny Halevy <bhalevy@panasas.com>
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>

1 files changed, 7 insertions, 0 deletions

diff --git a/include/linux/nfsd/state.h b/include/linux/nfsd/state.h
index 7faefc7c9d9a..5b3a6660f3af 100644
--- a/include/linux/nfsd/state.h
+++ b/include/linux/nfsd/state.h
@@ -132,6 +132,13 @@ nfsd4_get_session(struct nfsd4_session *ses)
         kref_get(&ses->se_ref);
 }
 
+/* formatted contents of nfs4_sessionid */
+struct nfsd4_sessionid {
+        clientid_t      clientid;
+        u32             sequence;
+        u32             reserved;
+};
+
 #define HEXDIR_LEN     33 /* hex version of 16 byte md5 of cl_name plus '\0' */
 
 /*