[PATCH 08/12] sunrpc/cache: retry cache lookups that return -ETIMEDOUT

NeilBrown
2009-08-04T05:25:05Z

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@suse.de>
---

fs/nfsd/export.c | 18 ++++++++++++++++++
net/sunrpc/svcauth_unix.c | 22 ++++++++++++++++++++--
2 files changed, 38 insertions(+), 2 deletions(-)

diff --git a/fs/nfsd/export.c b/fs/nfsd/export.c
index b92a276..6fcb0eb 100644
--- a/fs/nfsd/export.c
+++ b/fs/nfsd/export.c
@@ -783,9 +783,18 @@ 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);
+ }
if (err)
return ERR_PTR(err);
return ek;
@@ -855,9 +864,18 @@ 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/svcauth_unix.c b/net/sunrpc/svcauth_unix.c
index 5c865e2..f2de152 100644
--- a/net/sunrpc/svcauth_unix.c
+++ b/net/sunrpc/svcauth_unix.c
@@ -649,8 +649,10 @@ 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;
@@ -659,6 +661,13 @@ static int unix_gid_find(uid_t uid, struct group_info **gip,
*gip = ug->gi;
get_group_info(*gip);
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;
}
@@ -669,7 +678,7 @@ 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:
@@ -694,14 +703,23 @@ 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;