namei.c: let follow_link() do put_link() on failure

no need for kludgy "set cookie to ERR_PTR(...) because we failed before we did actual ->follow_link() and want to suppress put_link()", no pointless check in put_link() itself. Callers checked if follow_link() has failed anyway; might as well break out of their loops if that happened, without bothering to call put_link() first. [AV: folded fixes from hch] Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

namei.c: let follow_link() do put_link() on failure
no need for kludgy "set cookie to ERR_PTR(...) because we failed before we did actual ->follow_link() and want to suppress put_link()", no pointless check in put_link() itself. Callers checked if follow_link() has failed anyway; might as well break out of their loops if that happened, without bothering to call put_link() first. [AV: folded fixes from hch] Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Al Viro
1 parent 1d674107ea
Showing 1 changed file with 41 additions and 33 deletions Side-by-side Diff
fs/namei.c
@@ -605,7 +605,7 @@
 static inline void put_link(struct nameidata *nd, struct path *link, void *cookie)
 {
 	struct inode *inode = link->dentry->d_inode;
-	if (!IS_ERR(cookie) && inode->i_op->put_link)
+	if (inode->i_op->put_link)
 		inode->i_op->put_link(link->dentry, nd, cookie);
 	path_put(link);
 }
  
  
@@ -613,19 +613,19 @@
 static __always_inline int
 follow_link(struct path *link, struct nameidata *nd, void **p)
 {
-	int error;
 	struct dentry *dentry = link->dentry;
+	int error;
+	char *s;
  
 	BUG_ON(nd->flags & LOOKUP_RCU);
  
 	if (link->mnt == nd->path.mnt)
 		mntget(link->mnt);
  
-	if (unlikely(current->total_link_count >= 40)) {
-		*p = ERR_PTR(-ELOOP); /* no ->put_link(), please */
-		path_put(&nd->path);
-		return -ELOOP;
-	}
+	error = -ELOOP;
+	if (unlikely(current->total_link_count >= 40))
+		goto out_put_nd_path;
+
 	cond_resched();
 	current->total_link_count++;
  
  
  
  
@@ -633,31 +633,38 @@
 	nd_set_link(nd, NULL);
  
 	error = security_inode_follow_link(link->dentry, nd);
-	if (error) {
-		*p = ERR_PTR(error); /* no ->put_link(), please */
-		path_put(&nd->path);
-		return error;
-	}
+	if (error)
+		goto out_put_nd_path;
  
 	nd->last_type = LAST_BIND;
 	*p = dentry->d_inode->i_op->follow_link(dentry, nd);
 	error = PTR_ERR(*p);
-	if (!IS_ERR(*p)) {
-		char *s = nd_get_link(nd);
-		error = 0;
-		if (s)
-			error = __vfs_follow_link(nd, s);
-		else if (nd->last_type == LAST_BIND) {
-			nd->flags |= LOOKUP_JUMPED;
-			nd->inode = nd->path.dentry->d_inode;
-			if (nd->inode->i_op->follow_link) {
-				/* stepped on a _really_ weird one */
-				path_put(&nd->path);
-				error = -ELOOP;
-			}
+	if (IS_ERR(*p))
+		goto out_put_link;
+
+	error = 0;
+	s = nd_get_link(nd);
+	if (s) {
+		error = __vfs_follow_link(nd, s);
+	} else if (nd->last_type == LAST_BIND) {
+		nd->flags |= LOOKUP_JUMPED;
+		nd->inode = nd->path.dentry->d_inode;
+		if (nd->inode->i_op->follow_link) {
+			/* stepped on a _really_ weird one */
+			path_put(&nd->path);
+			error = -ELOOP;
 		}
 	}
+	if (unlikely(error))
+		put_link(nd, link, *p);
+
 	return error;
+
+out_put_nd_path:
+	path_put(&nd->path);
+out_put_link:
+	path_put(link);
+	return error;
 }
  
 static int follow_up_rcu(struct path *path)
@@ -1383,9 +1390,10 @@
 		void *cookie;
  
 		res = follow_link(&link, nd, &cookie);
-		if (!res)
-			res = walk_component(nd, path, &nd->last,
-					     nd->last_type, LOOKUP_FOLLOW);
+		if (res)
+			break;
+		res = walk_component(nd, path, &nd->last,
+				     nd->last_type, LOOKUP_FOLLOW);
 		put_link(nd, &link, cookie);
 	} while (res > 0);
  
@@ -1777,8 +1785,9 @@
 			struct path link = path;
 			nd->flags |= LOOKUP_PARENT;
 			err = follow_link(&link, nd, &cookie);
-			if (!err)
-				err = lookup_last(nd, &path);
+			if (err)
+				break;
+			err = lookup_last(nd, &path);
 			put_link(nd, &link, cookie);
 		}
 	}
@@ -2475,9 +2484,8 @@
 		nd->flags &= ~(LOOKUP_OPEN|LOOKUP_CREATE|LOOKUP_EXCL);
 		error = follow_link(&link, nd, &cookie);
 		if (unlikely(error))
-			filp = ERR_PTR(error);
-		else
-			filp = do_last(nd, &path, op, pathname);
+			goto out_filp;
+		filp = do_last(nd, &path, op, pathname);
 		put_link(nd, &link, cookie);
 	}
 out:
...	...	@@ -605,7 +605,7 @@
605	605	static inline void put_link(struct nameidata nd, struct path link, void *cookie)
606	606	{
607	607	struct inode *inode = link->dentry->d_inode;
608		- if (!IS_ERR(cookie) && inode->i_op->put_link)
	608	+ if (inode->i_op->put_link)
609	609	inode->i_op->put_link(link->dentry, nd, cookie);
610	610	path_put(link);
611	611	}
612	612
613	613
...	...	@@ -613,19 +613,19 @@
613	613	static __always_inline int
614	614	follow_link(struct path link, struct nameidata nd, void **p)
615	615	{
616		- int error;
617	616	struct dentry *dentry = link->dentry;
	617	+ int error;
	618	+ char *s;
618	619
619	620	BUG_ON(nd->flags & LOOKUP_RCU);
620	621
621	622	if (link->mnt == nd->path.mnt)
622	623	mntget(link->mnt);
623	624
624		- if (unlikely(current->total_link_count >= 40)) {
625		- p = ERR_PTR(-ELOOP); / no ->put_link(), please */
626		- path_put(&nd->path);
627		- return -ELOOP;
628		- }
	625	+ error = -ELOOP;
	626	+ if (unlikely(current->total_link_count >= 40))
	627	+ goto out_put_nd_path;
	628	+
629	629	cond_resched();
630	630	current->total_link_count++;
631	631
632	632
633	633
634	634
...	...	@@ -633,31 +633,38 @@
633	633	nd_set_link(nd, NULL);
634	634
635	635	error = security_inode_follow_link(link->dentry, nd);
636		- if (error) {
637		- p = ERR_PTR(error); / no ->put_link(), please */
638		- path_put(&nd->path);
639		- return error;
640		- }
	636	+ if (error)
	637	+ goto out_put_nd_path;
641	638
642	639	nd->last_type = LAST_BIND;
643	640	*p = dentry->d_inode->i_op->follow_link(dentry, nd);
644	641	error = PTR_ERR(*p);
645		- if (!IS_ERR(*p)) {
646		- char *s = nd_get_link(nd);
647		- error = 0;
648		- if (s)
649		- error = __vfs_follow_link(nd, s);
650		- else if (nd->last_type == LAST_BIND) {
651		- nd->flags \|= LOOKUP_JUMPED;
652		- nd->inode = nd->path.dentry->d_inode;
653		- if (nd->inode->i_op->follow_link) {
654		- /* stepped on a _really_ weird one */
655		- path_put(&nd->path);
656		- error = -ELOOP;
657		- }
	642	+ if (IS_ERR(*p))
	643	+ goto out_put_link;
	644	+
	645	+ error = 0;
	646	+ s = nd_get_link(nd);
	647	+ if (s) {
	648	+ error = __vfs_follow_link(nd, s);
	649	+ } else if (nd->last_type == LAST_BIND) {
	650	+ nd->flags \|= LOOKUP_JUMPED;
	651	+ nd->inode = nd->path.dentry->d_inode;
	652	+ if (nd->inode->i_op->follow_link) {
	653	+ /* stepped on a _really_ weird one */
	654	+ path_put(&nd->path);
	655	+ error = -ELOOP;
658	656	}
659	657	}
	658	+ if (unlikely(error))
	659	+ put_link(nd, link, *p);
	660	+
660	661	return error;
	662	+
	663	+out_put_nd_path:
	664	+ path_put(&nd->path);
	665	+out_put_link:
	666	+ path_put(link);
	667	+ return error;
661	668	}
662	669
663	670	static int follow_up_rcu(struct path *path)
...	...	@@ -1383,9 +1390,10 @@
1383	1390	void *cookie;
1384	1391
1385	1392	res = follow_link(&link, nd, &cookie);
1386		- if (!res)
1387		- res = walk_component(nd, path, &nd->last,
1388		- nd->last_type, LOOKUP_FOLLOW);
	1393	+ if (res)
	1394	+ break;
	1395	+ res = walk_component(nd, path, &nd->last,
	1396	+ nd->last_type, LOOKUP_FOLLOW);
1389	1397	put_link(nd, &link, cookie);
1390	1398	} while (res > 0);
1391	1399
...	...	@@ -1777,8 +1785,9 @@
1777	1785	struct path link = path;
1778	1786	nd->flags \|= LOOKUP_PARENT;
1779	1787	err = follow_link(&link, nd, &cookie);
1780		- if (!err)
1781		- err = lookup_last(nd, &path);
	1788	+ if (err)
	1789	+ break;
	1790	+ err = lookup_last(nd, &path);
1782	1791	put_link(nd, &link, cookie);
1783	1792	}
1784	1793	}
...	...	@@ -2475,9 +2484,8 @@
2475	2484	nd->flags &= ~(LOOKUP_OPEN\|LOOKUP_CREATE\|LOOKUP_EXCL);
2476	2485	error = follow_link(&link, nd, &cookie);
2477	2486	if (unlikely(error))
2478		- filp = ERR_PTR(error);
2479		- else
2480		- filp = do_last(nd, &path, op, pathname);
	2487	+ goto out_filp;
	2488	+ filp = do_last(nd, &path, op, pathname);
2481	2489	put_link(nd, &link, cookie);
2482	2490	}
2483	2491	out: