On Wed, Sep 09, 2009 at 04:32:54PM +1000, NeilBrown wrote:
> If cache_check returns -ETIMEDOUT, then the cache item is not
> up-to-date, but there is no pending upcall.
> This could mean the data is not available, or it could mean that the
> good data has been stored in a new cache item.
>
> So re-do the lookup and if that returns a new item, proceed using that
> item.
>
> Signed-off-by: NeilBrown <neilb@xxxxxxx>
> ---
>
> fs/nfsd/export.c | 18 ++++++++++++++++++
> net/sunrpc/auth_gss/svcauth_gss.c | 18 ++++++++++++++----
> net/sunrpc/svcauth_unix.c | 22 ++++++++++++++++++++--
> 3 files changed, 52 insertions(+), 6 deletions(-)
>
> diff --git a/fs/nfsd/export.c b/fs/nfsd/export.c
> index 984a5eb..ec0f0d9 100644
> --- a/fs/nfsd/export.c
> +++ b/fs/nfsd/export.c
> @@ -793,9 +793,18 @@ exp_find_key(svc_client *clp, int fsid_type, u32 *fsidv, struct cache_req *reqp)
> memcpy(key.ek_fsid, fsidv, key_len(fsid_type));
>
> ek = svc_expkey_lookup(&key);
> + again:
> if (ek == NULL)
> return ERR_PTR(-ENOMEM);
> err = cache_check(&svc_expkey_cache, &ek->h, reqp);
> + if (err == -ETIMEDOUT) {
> + struct svc_expkey *prev_ek = ek;
> + ek = svc_expkey_lookup(&key);
> + if (ek != prev_ek)
> + goto again;
> + if (ek)
> + cache_put(&ek->h, &svc_expkey_cache);
> + }
This is very subtle. (We're comparing to a pointer which may not
actually point to anything any more.) And it's repeated in every
caller. Is there any simpler way to handle this?
--b.
> if (err)
> return ERR_PTR(err);
> return ek;
> @@ -865,9 +874,18 @@ static svc_export *exp_get_by_name(svc_client *clp, const struct path *path,
> key.ex_path = *path;
>
> exp = svc_export_lookup(&key);
> + retry:
> if (exp == NULL)
> return ERR_PTR(-ENOMEM);
> err = cache_check(&svc_export_cache, &exp->h, reqp);
> + if (err == -ETIMEDOUT) {
> + struct svc_export *prev_exp = exp;
> + exp = svc_export_lookup(&key);
> + if (exp != prev_exp)
> + goto retry;
> + if (exp)
> + cache_put(&exp->h, &svc_export_cache);
> + }
> if (err)
> return ERR_PTR(err);
> return exp;
> diff --git a/net/sunrpc/auth_gss/svcauth_gss.c b/net/sunrpc/auth_gss/svcauth_gss.c
> index f6c51e5..c4e9177 100644
> --- a/net/sunrpc/auth_gss/svcauth_gss.c
> +++ b/net/sunrpc/auth_gss/svcauth_gss.c
> @@ -999,7 +999,7 @@ static int svcauth_gss_handle_init(struct svc_rqst *rqstp,
> struct kvec *argv = &rqstp->rq_arg.head[0];
> struct kvec *resv = &rqstp->rq_res.head[0];
> struct xdr_netobj tmpobj;
> - struct rsi *rsip, rsikey;
> + struct rsi *rsip, rsikey, *prev_rsi;
> int ret;
>
> /* Read the verifier; should be NULL: */
> @@ -1029,15 +1029,24 @@ static int svcauth_gss_handle_init(struct svc_rqst *rqstp,
> }
>
> /* Perform upcall, or find upcall result: */
> + retry:
> rsip = rsi_lookup(&rsikey);
> - rsi_free(&rsikey);
> - if (!rsip)
> + if (!rsip) {
> + rsi_free(&rsikey);
> return SVC_DROP;
> + }
> switch (cache_check(&rsi_cache, &rsip->h, &rqstp->rq_chandle)) {
> - case -EAGAIN:
> case -ETIMEDOUT:
> + prev_rsi = rsip;
> + rsip = rsi_lookup(&rsikey);
> + if (rsip != prev_rsi)
> + goto retry;
> + if (rsip)
> + cache_put(&rsip->h, &rsi_cache);
> + case -EAGAIN:
> case -ENOENT:
> /* No upcall result: */
> + rsi_free(&rsikey);
> return SVC_DROP;
> case 0:
> ret = SVC_DROP;
> @@ -1059,6 +1068,7 @@ static int svcauth_gss_handle_init(struct svc_rqst *rqstp,
> }
> ret = SVC_COMPLETE;
> out:
> + rsi_free(&rsikey);
> cache_put(&rsip->h, &rsi_cache);
> return ret;
> }
> diff --git a/net/sunrpc/svcauth_unix.c b/net/sunrpc/svcauth_unix.c
> index 117f68a..f9122df 100644
> --- a/net/sunrpc/svcauth_unix.c
> +++ b/net/sunrpc/svcauth_unix.c
> @@ -659,8 +659,10 @@ static int unix_gid_find(uid_t uid, struct group_info **gip,
> struct svc_rqst *rqstp)
> {
> struct unix_gid *ug = unix_gid_lookup(uid);
> + struct unix_gid *prevug;
> if (!ug)
> return -EAGAIN;
> + retry:
> switch (cache_check(&unix_gid_cache, &ug->h, &rqstp->rq_chandle)) {
> case -ENOENT:
> *gip = NULL;
> @@ -670,6 +672,13 @@ static int unix_gid_find(uid_t uid, struct group_info **gip,
> get_group_info(*gip);
> cache_put(&ug->h, &unix_gid_cache);
> return 0;
> + case -ETIMEDOUT:
> + prevug = ug;
> + ug = unix_gid_lookup(uid);
> + if (ug != prevug)
> + goto retry;
> + if (ug)
> + cache_put(&ug->h, &unix_gid_cache);
> default:
> return -EAGAIN;
> }
> @@ -680,7 +689,7 @@ svcauth_unix_set_client(struct svc_rqst *rqstp)
> {
> struct sockaddr_in *sin;
> struct sockaddr_in6 *sin6, sin6_storage;
> - struct ip_map *ipm;
> + struct ip_map *ipm, *prev_ipm;
>
> switch (rqstp->rq_addr.ss_family) {
> case AF_INET:
> @@ -705,14 +714,23 @@ svcauth_unix_set_client(struct svc_rqst *rqstp)
> ipm = ip_map_lookup(rqstp->rq_server->sv_program->pg_class,
> &sin6->sin6_addr);
>
> + retry:
> if (ipm == NULL)
> return SVC_DENIED;
>
> switch (cache_check(&ip_map_cache, &ipm->h, &rqstp->rq_chandle)) {
> default:
> BUG();
> - case -EAGAIN:
> case -ETIMEDOUT:
> + prev_ipm = ipm;
> + ipm = ip_map_lookup(rqstp->rq_server->sv_program->pg_class,
> + &sin6->sin6_addr);
> + if (ipm != prev_ipm)
> + goto retry;
> + if (ipm)
> + cache_put(&ipm->h, &ip_map_cache);
> +
> + case -EAGAIN:
> return SVC_DROP;
> case -ENOENT:
> return SVC_DENIED;
>
>
--
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