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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>
wifi-calibration
Marc Eshel 2009-04-03 08:27:52 +03:00 committed by J. Bruce Fields
parent c4bf786806
commit 5282fd724b
2 changed files with 61 additions and 1 deletions
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55
fs/nfsd/nfs4state.c
View File

@ -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]);
}

7
include/linux/nfsd/state.h
View File

@ -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' */
/*