[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>

[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>
NeilBrown · Linus Torvalds
1 parent efc36aa560
Showing 2 changed files with 44 additions and 36 deletions Side-by-side Diff
fs/nfsd/export.c
include/linux/nfsd/export.h
@@ -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;
 }
@@ -67,7 +67,8 @@
 	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 @@
 {
 	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__ */
...	...	@@ -73,8 +73,10 @@
73	73	if (cache_put(item, cd)) {
74	74	struct svc_expkey *key = container_of(item, struct svc_expkey, h);
75	75	if (test_bit(CACHE_VALID, &item->flags) &&
76		- !test_bit(CACHE_NEGATIVE, &item->flags))
77		- exp_put(key->ek_export);
	76	+ !test_bit(CACHE_NEGATIVE, &item->flags)) {
	77	+ dput(key->ek_dentry);
	78	+ mntput(key->ek_mnt);
	79	+ }
78	80	auth_domain_put(key->ek_client);
79	81	kfree(key);
80	82	}
81	83
82	84
83	85
...	...	@@ -164,26 +166,18 @@
164	166	} else {
165	167	struct nameidata nd;
166	168	struct svc_expkey *ek;
167		- struct svc_export *exp;
168	169	err = path_lookup(buf, 0, &nd);
169	170	if (err)
170	171	goto out;
171	172
172	173	dprintk("Found the path %s\n", buf);
173		- exp = exp_get_by_name(dom, nd.mnt, nd.dentry, NULL);
174		-
175		- err = -ENOENT;
176		- if (!exp)
177		- goto out_nd;
178		- key.ek_export = exp;
179		- dprintk("And found export\n");
	174	+ key.ek_mnt = nd.mnt;
	175	+ key.ek_dentry = nd.dentry;
180	176
181	177	ek = svc_expkey_lookup(&key, 1);
182	178	if (ek)
183	179	expkey_put(&ek->h, &svc_expkey_cache);
184		- exp_put(exp);
185	180	err = 0;
186		- out_nd:
187	181	path_release(&nd);
188	182	}
189	183	cache_flush();
...	...	@@ -214,7 +208,7 @@
214	208	if (test_bit(CACHE_VALID, &h->flags) &&
215	209	!test_bit(CACHE_NEGATIVE, &h->flags)) {
216	210	seq_printf(m, " ");
217		- seq_path(m, ek->ek_export->ex_mnt, ek->ek_export->ex_dentry, "\ \t\n");
	211	+ seq_path(m, ek->ek_mnt, ek->ek_dentry, "\ \t\n");
218	212	}
219	213	seq_printf(m, "\n");
220	214	return 0;
...	...	@@ -252,8 +246,8 @@
252	246
253	247	static inline void svc_expkey_update(struct svc_expkey new, struct svc_expkey item)
254	248	{
255		- cache_get(&item->ek_export->h);
256		- new->ek_export = item->ek_export;
	249	+ new->ek_mnt = mntget(item->ek_mnt);
	250	+ new->ek_dentry = dget(item->ek_dentry);
257	251	}
258	252
259	253	static DefineSimpleCacheLookup(svc_expkey,0) /* no inplace updates */
...	...	@@ -519,7 +513,8 @@
519	513	key.ek_client = clp;
520	514	key.ek_fsidtype = fsid_type;
521	515	memcpy(key.ek_fsid, fsidv, key_len(fsid_type));
522		- key.ek_export = exp;
	516	+ key.ek_mnt = exp->ex_mnt;
	517	+ key.ek_dentry = exp->ex_dentry;
523	518	key.h.expiry_time = NEVER;
524	519	key.h.flags = 0;
525	520
...	...	@@ -741,8 +736,8 @@
741	736	if ((nxp->ex_flags & NFSEXP_FSID) &&
742	737	(fsid_key = exp_get_fsid_key(clp, nxp->ex_dev)) &&
743	738	!IS_ERR(fsid_key) &&
744		- fsid_key->ek_export &&
745		- fsid_key->ek_export != exp)
	739	+ fsid_key->ek_mnt &&
	740	+ (fsid_key->ek_mnt != nd.mnt \|\| fsid_key->ek_dentry != nd.dentry) )
746	741	goto finish;
747	742
748	743	if (exp) {
...	...	@@ -912,6 +907,24 @@
912	907	return err;
913	908	}
914	909
	910	+struct svc_export *
	911	+exp_find(struct auth_domain clp, int fsid_type, u32 fsidv,
	912	+ struct cache_req *reqp)
	913	+{
	914	+ struct svc_export *exp;
	915	+ struct svc_expkey *ek = exp_find_key(clp, fsid_type, fsidv, reqp);
	916	+ if (!ek \|\| IS_ERR(ek))
	917	+ return ERR_PTR(PTR_ERR(ek));
	918	+
	919	+ exp = exp_get_by_name(clp, ek->ek_mnt, ek->ek_dentry, reqp);
	920	+ expkey_put(&ek->h, &svc_expkey_cache);
	921	+
	922	+ if (!exp \|\| IS_ERR(exp))
	923	+ return ERR_PTR(PTR_ERR(exp));
	924	+ return exp;
	925	+}
	926	+
	927	+
915	928	/*
916	929	* Called when we need the filehandle for the root of the pseudofs,
917	930	* for a given NFSv4 client. The root is defined to be the
...	...	@@ -922,6 +935,7 @@
922	935	struct cache_req *creq)
923	936	{
924	937	struct svc_expkey *fsid_key;
	938	+ struct svc_export *exp;
925	939	int rv;
926	940	u32 fsidv[2];
927	941
...	...	@@ -933,8 +947,14 @@
933	947	if (!fsid_key \|\| IS_ERR(fsid_key))
934	948	return nfserr_perm;
935	949
936		- rv = fh_compose(fhp, fsid_key->ek_export,
937		- fsid_key->ek_export->ex_dentry, NULL);
	950	+ exp = exp_get_by_name(clp, fsid_key->ek_mnt, fsid_key->ek_dentry, creq);
	951	+ if (exp == NULL)
	952	+ rv = nfserr_perm;
	953	+ else if (IS_ERR(exp))
	954	+ rv = nfserrno(PTR_ERR(exp));
	955	+ else
	956	+ rv = fh_compose(fhp, exp,
	957	+ fsid_key->ek_dentry, NULL);
938	958	expkey_put(&fsid_key->h, &svc_expkey_cache);
939	959	return rv;
940	960	}
...	...	@@ -67,7 +67,8 @@
67	67	int ek_fsidtype;
68	68	u32 ek_fsid[3];
69	69
70		- struct svc_export * ek_export;
	70	+ struct vfsmount * ek_mnt;
	71	+ struct dentry * ek_dentry;
71	72	};
72	73
73	74	#define EX_SECURE(exp) (!((exp)->ex_flags & NFSEXP_INSECURE_PORT))
74	75
...	...	@@ -114,22 +115,9 @@
114	115	{
115	116	cache_get(&exp->h);
116	117	}
117		-static inline struct svc_export *
	118	+extern struct svc_export *
118	119	exp_find(struct auth_domain clp, int fsid_type, u32 fsidv,
119		- struct cache_req *reqp)
120		-{
121		- struct svc_expkey *ek = exp_find_key(clp, fsid_type, fsidv, reqp);
122		- if (ek && !IS_ERR(ek)) {
123		- struct svc_export *exp = ek->ek_export;
124		- int err;
125		- exp_get(exp);
126		- expkey_put(&ek->h, &svc_expkey_cache);
127		- if ((err = cache_check(&svc_export_cache, &exp->h, reqp)))
128		- exp = ERR_PTR(err);
129		- return exp;
130		- } else
131		- return ERR_PTR(PTR_ERR(ek));
132		-}
	120	+ struct cache_req *reqp);
133	121
134	122	#endif /* __KERNEL__ */
135	123