[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>
diff --git a/fs/nfsd/export.c b/fs/nfsd/export.c
index ac09977..587829e 100644
--- a/fs/nfsd/export.c
+++ b/fs/nfsd/export.c
@@ -73,8 +73,10 @@
if (cache_put(item, cd)) {
struct svc_expkey *key = container_of(item, struct svc_expkey, h);
if (test_bit(CACHE_VALID, &item->flags) &&
- !test_bit(CACHE_NEGATIVE, &item->flags))
- exp_put(key->ek_export);
+ !test_bit(CACHE_NEGATIVE, &item->flags)) {
+ dput(key->ek_dentry);
+ mntput(key->ek_mnt);
+ }
auth_domain_put(key->ek_client);
kfree(key);
}
@@ -164,26 +166,18 @@
} else {
struct nameidata nd;
struct svc_expkey *ek;
- struct svc_export *exp;
err = path_lookup(buf, 0, &nd);
if (err)
goto out;
dprintk("Found the path %s\n", buf);
- exp = exp_get_by_name(dom, nd.mnt, nd.dentry, NULL);
-
- err = -ENOENT;
- if (!exp)
- goto out_nd;
- key.ek_export = exp;
- dprintk("And found export\n");
+ key.ek_mnt = nd.mnt;
+ key.ek_dentry = nd.dentry;
ek = svc_expkey_lookup(&key, 1);
if (ek)
expkey_put(&ek->h, &svc_expkey_cache);
- exp_put(exp);
err = 0;
- out_nd:
path_release(&nd);
}
cache_flush();
@@ -214,7 +208,7 @@
if (test_bit(CACHE_VALID, &h->flags) &&
!test_bit(CACHE_NEGATIVE, &h->flags)) {
seq_printf(m, " ");
- seq_path(m, ek->ek_export->ex_mnt, ek->ek_export->ex_dentry, "\\ \t\n");
+ seq_path(m, ek->ek_mnt, ek->ek_dentry, "\\ \t\n");
}
seq_printf(m, "\n");
return 0;
@@ -252,8 +246,8 @@
static inline void svc_expkey_update(struct svc_expkey *new, struct svc_expkey *item)
{
- cache_get(&item->ek_export->h);
- new->ek_export = item->ek_export;
+ new->ek_mnt = mntget(item->ek_mnt);
+ new->ek_dentry = dget(item->ek_dentry);
}
static DefineSimpleCacheLookup(svc_expkey,0) /* no inplace updates */
@@ -519,7 +513,8 @@
key.ek_client = clp;
key.ek_fsidtype = fsid_type;
memcpy(key.ek_fsid, fsidv, key_len(fsid_type));
- key.ek_export = exp;
+ key.ek_mnt = exp->ex_mnt;
+ key.ek_dentry = exp->ex_dentry;
key.h.expiry_time = NEVER;
key.h.flags = 0;
@@ -741,8 +736,8 @@
if ((nxp->ex_flags & NFSEXP_FSID) &&
(fsid_key = exp_get_fsid_key(clp, nxp->ex_dev)) &&
!IS_ERR(fsid_key) &&
- fsid_key->ek_export &&
- fsid_key->ek_export != exp)
+ fsid_key->ek_mnt &&
+ (fsid_key->ek_mnt != nd.mnt || fsid_key->ek_dentry != nd.dentry) )
goto finish;
if (exp) {
@@ -912,6 +907,24 @@
return err;
}
+struct svc_export *
+exp_find(struct auth_domain *clp, int fsid_type, u32 *fsidv,
+ struct cache_req *reqp)
+{
+ struct svc_export *exp;
+ struct svc_expkey *ek = exp_find_key(clp, fsid_type, fsidv, reqp);
+ if (!ek || IS_ERR(ek))
+ return ERR_PTR(PTR_ERR(ek));
+
+ exp = exp_get_by_name(clp, ek->ek_mnt, ek->ek_dentry, reqp);
+ expkey_put(&ek->h, &svc_expkey_cache);
+
+ if (!exp || IS_ERR(exp))
+ return ERR_PTR(PTR_ERR(exp));
+ return exp;
+}
+
+
/*
* Called when we need the filehandle for the root of the pseudofs,
* for a given NFSv4 client. The root is defined to be the
@@ -922,6 +935,7 @@
struct cache_req *creq)
{
struct svc_expkey *fsid_key;
+ struct svc_export *exp;
int rv;
u32 fsidv[2];
@@ -933,8 +947,14 @@
if (!fsid_key || IS_ERR(fsid_key))
return nfserr_perm;
- rv = fh_compose(fhp, fsid_key->ek_export,
- fsid_key->ek_export->ex_dentry, NULL);
+ exp = exp_get_by_name(clp, fsid_key->ek_mnt, fsid_key->ek_dentry, creq);
+ if (exp == NULL)
+ rv = nfserr_perm;
+ else if (IS_ERR(exp))
+ rv = nfserrno(PTR_ERR(exp));
+ else
+ rv = fh_compose(fhp, exp,
+ fsid_key->ek_dentry, NULL);
expkey_put(&fsid_key->h, &svc_expkey_cache);
return rv;
}