On Nov. 10, 2008, 22:44 +0200, Benny Halevy <bhalevy@xxxxxxxxxxx> wrote:
> From: Marc Eshel <eshel@xxxxxxxxxxxxxxx>
>
> Use crc32 of sessionid to look it up on the server.
> Select CRC32 when NFSD_V4_1 is selected in fs/Kconfig.
>
> Signed-off-by: Benny Halevy <bhalevy@xxxxxxxxxxx>
> ---
> fs/Kconfig | 1 +
> fs/nfsd/nfs4state.c | 51 +++++++++++++++++++++++++++++++++++++++++++++++++++
> 2 files changed, 52 insertions(+), 0 deletions(-)
>
> diff --git a/fs/Kconfig b/fs/Kconfig
> index aee944e..cb0e3de 100644
> --- a/fs/Kconfig
> +++ b/fs/Kconfig
> @@ -1320,6 +1320,7 @@ config NFSD_V4
> config NFSD_V4_1
> bool "NFS server support for NFSv4.1 (EXPERIMENTAL)"
> depends on NFSD_V4 && EXPERIMENTAL
> + select CRC32
> help
> This option enables support for minor version 1 of the NFSv4 protocol
> (draft-ietf-nfsv4-minorversion1) in the kernel's NFS server.
> diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
> index bf4d2c2..0e1bc72 100644
> --- a/fs/nfsd/nfs4state.c
> +++ b/fs/nfsd/nfs4state.c
> @@ -52,6 +52,7 @@
> #include <linux/namei.h>
> #include <linux/swap.h>
> #include <linux/mutex.h>
> +#include <linux/crc32.h>
> #include <linux/lockd/bind.h>
> #include <linux/module.h>
>
> @@ -311,6 +312,52 @@ static struct list_head client_lru;
> static struct list_head close_lru;
>
> #if defined(CONFIG_NFSD_V4_1)
> +/* Use a prime for hash table size */
> +#define SESSION_HASH_SIZE 1031
review 11-12: reduce to 512
> +static struct list_head sessionid_hashtbl[SESSION_HASH_SIZE];
> +
> +static int
> +hash_sessionid(nfs41_sessionid *sessionid)
> +{
> + u32 csum = 0;
> + int idx;
> +
> + csum = crc32(0, sessionid, sizeof(*sessionid));
why use crc32?
re-use one of the available in linux/hash.h
> + idx = csum % SESSION_HASH_SIZE;
> + dprintk("%s IDX: %u csum %u\n", __func__, idx, csum);
ditch that
> + return idx;
> +}
> +
> +static inline void
> +dump_sessionid(const char *fn, nfs41_sessionid *sessionid)
> +{
> + u32 *ptr = (u32 *)(*sessionid);
> + dprintk("%s: %u:%u:%u:%u\n", fn, ptr[0], ptr[1], ptr[2], ptr[3]);
> +}
> +
> +struct nfs41_session *
> +find_in_sessionid_hashtbl(nfs41_sessionid *sessionid)
> +{
> + struct nfs41_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, sessionid,
> + sizeof(nfs41_sessionid))) {
> + dprintk("%s: found session %p\n", __func__, elem);
can probably get rid of the dprintk
> + return elem;
> + }
> + }
> +
> + dprintk("%s: session not found\n", __func__);
> + return NULL;
> +}
> +
> static void
> destroy_session(struct nfs41_session *ses)
> {
> @@ -3154,6 +3201,10 @@ 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]);
> }
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