From: Marc Eshel <eshel@xxxxxxxxxxxxxxx>
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@xxxxxxxxxxx>
[we don't use a prime for sessionid hash table size]
[use sessionid_lock spin lock]
Signed-off-by: Benny Halevy <bhalevy@xxxxxxxxxxx>
---
fs/nfsd/nfs4state.c | 57 +++++++++++++++++++++++++++++++++++++++++++-
include/linux/nfsd/state.h | 7 +++++
2 files changed, 63 insertions(+), 1 deletions(-)
diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index df9d42e..ac4e8f2 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -383,11 +383,62 @@ static void release_openowner(struct nfs4_stateowner *sop)
}
#if defined(CONFIG_NFSD_V4_1)
+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);
}
@@ -3213,6 +3264,10 @@ nfs4_state_init(void)
INIT_LIST_HEAD(&unconf_str_hashtbl[i]);
INIT_LIST_HEAD(&unconf_id_hashtbl[i]);
}
+#if defined(CONFIG_NFSD_V4_1)
+ for (i = 0; i < SESSION_HASH_SIZE; i++)
+ INIT_LIST_HEAD(&sessionid_hashtbl[i]);
+#endif /* CONFIG_NFSD_V4_1 */
for (i = 0; i < FILE_HASH_SIZE; i++) {
INIT_LIST_HEAD(&file_hashtbl[i]);
}
diff --git a/include/linux/nfsd/state.h b/include/linux/nfsd/state.h
index 29624b4..7592d7b 100644
--- a/include/linux/nfsd/state.h
+++ b/include/linux/nfsd/state.h
@@ -133,6 +133,13 @@ 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' */
/*
--
1.6.2.1
--
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