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>
diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index f23385b..fc20e1f 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -382,11 +382,62 @@
nfs4_put_stateowner(sop);
}
+static DEFINE_SPINLOCK(sessionid_lock);
+#define SESSION_HASH_SIZE 512
+static struct list_head sessionid_hashtbl[SESSION_HASH_SIZE];
+
+static inline int
+hash_sessionid(struct nfs4_sessionid *sessionid)
+{
+ struct nfsd4_sessionid *sid = (struct nfsd4_sessionid *)sessionid;
+
+ return sid->sequence % SESSION_HASH_SIZE;
+}
+
+static inline void
+dump_sessionid(const char *fn, struct nfs4_sessionid *sessionid)
+{
+ u32 *ptr = (u32 *)(&sessionid->data[0]);
+ dprintk("%s: %u:%u:%u:%u\n", fn, ptr[0], ptr[1], ptr[2], ptr[3]);
+}
+
+/* caller must hold sessionid_lock */
+static struct nfsd4_session *
+find_in_sessionid_hashtbl(struct nfs4_sessionid *sessionid)
+{
+ struct nfsd4_session *elem;
+ int idx;
+
+ dump_sessionid(__func__, sessionid);
+ idx = hash_sessionid(sessionid);
+ dprintk("%s: idx is %d\n", __func__, idx);
+ /* Search in the appropriate list */
+ list_for_each_entry(elem, &sessionid_hashtbl[idx], se_hash) {
+ dump_sessionid("list traversal", &elem->se_sessionid);
+ if (!memcmp(elem->se_sessionid.data, sessionid->data,
+ NFS4_MAX_SESSIONID_LEN)) {
+ return elem;
+ }
+ }
+
+ dprintk("%s: session not found\n", __func__);
+ return NULL;
+}
+
+/* caller must hold sessionid_lock */
static void
-release_session(struct nfsd4_session *ses)
+unhash_session(struct nfsd4_session *ses)
{
list_del(&ses->se_hash);
list_del(&ses->se_perclnt);
+}
+
+static void
+release_session(struct nfsd4_session *ses)
+{
+ spin_lock(&sessionid_lock);
+ unhash_session(ses);
+ spin_unlock(&sessionid_lock);
nfsd4_put_session(ses);
}
@@ -3205,6 +3256,8 @@
INIT_LIST_HEAD(&unconf_str_hashtbl[i]);
INIT_LIST_HEAD(&unconf_id_hashtbl[i]);
}
+ for (i = 0; i < SESSION_HASH_SIZE; i++)
+ INIT_LIST_HEAD(&sessionid_hashtbl[i]);
for (i = 0; i < FILE_HASH_SIZE; i++) {
INIT_LIST_HEAD(&file_hashtbl[i]);
}