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

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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>
This commit is contained in:
NeilBrown
2006-03-27 01:15:00 -08:00
committed by Linus Torvalds
parent efc36aa560
commit eab7e2e647
2 changed files with 44 additions and 36 deletions
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20
include/linux/nfsd/export.h
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@@ -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__ */