[PATCH] knfsd: Break the hard linkage from svc_expkey to svc_export

Current svc_expkey holds a pointer to the svc_export structure, so updates to
that structure have to be in-place, which is a wart on the whole cache
infrastruct.  So we break that linkage and just do a second lookup.

If this became a performance issue, it would be possible to put a direct link
back in which was only used conditionally.  i.e.  when an object is replaced
in the cache, we set a flag in the old object.  When dereferencing the link
from svc_expkey, if the flag is set, we drop the reference and do a fresh
lookup.

Signed-off-by: Neil Brown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 4 insertions, 16 deletions

diff --git a/include/linux/nfsd/export.h b/include/linux/nfsd/export.h
index 6bad4766d3d9..d52e0b7ad37b 100644
--- a/include/linux/nfsd/export.h
+++ b/include/linux/nfsd/export.h
@@ -67,7 +67,8 @@ struct svc_expkey {
         int                     ek_fsidtype;
         u32                     ek_fsid[3];
 
-        struct svc_export *     ek_export;
+        struct vfsmount *       ek_mnt;
+        struct dentry *         ek_dentry;
 };
 
 #define EX_SECURE(exp)          (!((exp)->ex_flags & NFSEXP_INSECURE_PORT))
@@ -114,22 +115,9 @@ static inline void exp_get(struct svc_export *exp)
 {
         cache_get(&exp->h);
 }
-static inline struct svc_export *
+extern struct svc_export *
 exp_find(struct auth_domain *clp, int fsid_type, u32 *fsidv,
-         struct cache_req *reqp)
-{
-        struct svc_expkey *ek = exp_find_key(clp, fsid_type, fsidv, reqp);
-        if (ek && !IS_ERR(ek)) {
-                struct svc_export *exp = ek->ek_export;
-                int err;
-                exp_get(exp);
-                expkey_put(&ek->h, &svc_expkey_cache);
-                if ((err = cache_check(&svc_export_cache, &exp->h, reqp)))
-                        exp = ERR_PTR(err);
-                return exp;
-        } else
-                return ERR_PTR(PTR_ERR(ek));
-}
+         struct cache_req *reqp);
 
 #endif /* __KERNEL__ */