From 5282fd724b667b7d65f2e41e405a825e58a78813 Mon Sep 17 00:00:00 2001 From: Marc Eshel Date: Fri, 3 Apr 2009 08:27:52 +0300 Subject: [PATCH] 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 [we don't use a prime for sessionid hash table size] [use sessionid_lock spin lock] Signed-off-by: Benny Halevy Signed-off-by: J. Bruce Fields --- fs/nfsd/nfs4state.c | 55 +++++++++++++++++++++++++++++++++++++- include/linux/nfsd/state.h | 7 +++++ 2 files changed, 61 insertions(+), 1 deletion(-) diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c index f23385b13065..fc20e1f38d75 100644 --- a/fs/nfsd/nfs4state.c +++ b/fs/nfsd/nfs4state.c @@ -382,11 +382,62 @@ static void release_openowner(struct nfs4_stateowner *sop) 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 @@ nfs4_state_init(void) 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]); } 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' */ /* -- 2.39.2