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From: Al Viro <viro@ZenIV.linux.org.uk>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Neil Brown <neilb@suse.de>,
	linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org
Subject: [PATCH 12/24] link_path_walk: turn inner loop into explicit goto
Date: Mon, 20 Apr 2015 19:12:56 +0100	[thread overview]
Message-ID: <1429553588-24764-12-git-send-email-viro@ZenIV.linux.org.uk> (raw)
In-Reply-To: <20150420181222.GK889@ZenIV.linux.org.uk>

From: Al Viro <viro@zeniv.linux.org.uk>

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
 fs/namei.c | 61 ++++++++++++++++++++++++++++++++-----------------------------
 1 file changed, 32 insertions(+), 29 deletions(-)

diff --git a/fs/namei.c b/fs/namei.c
index 5366b6d..86d54e5 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -1832,6 +1832,10 @@ static int link_path_walk(const char *name, struct nameidata *nd)
 			return err;
 
 		if (err) {
+			struct path link;
+			void *cookie;
+			char *s;
+
 			if (unlikely(nd->link_count >= MAX_NESTED_LINKS)) {
 				path_put_conditional(&next, nd);
 				path_put(&nd->path);
@@ -1842,41 +1846,40 @@ static int link_path_walk(const char *name, struct nameidata *nd)
 			nd->depth++;
 			nd->link_count++;
 
-			do {
-				struct path link = next;
-				void *cookie;
-				char *s = get_link(&link, nd, &cookie);
-
-				if (unlikely(IS_ERR(s))) {
-					err = PTR_ERR(s);
-					nd->link_count--;
-					nd->depth--;
-					return err;
+l:
+			link = next;
+			s = get_link(&link, nd, &cookie);
+
+			if (unlikely(IS_ERR(s))) {
+				err = PTR_ERR(s);
+				nd->link_count--;
+				nd->depth--;
+				return err;
+			}
+			err = 0;
+			if (unlikely(!s)) {
+				/* jumped */
+				put_link(nd, &link, cookie);
+			} else {
+				if (*s == '/') {
+					if (!nd->root.mnt)
+						set_root(nd);
+					path_put(&nd->path);
+					nd->path = nd->root;
+					path_get(&nd->root);
+					nd->flags |= LOOKUP_JUMPED;
 				}
-				err = 0;
-				if (unlikely(!s)) {
-					/* jumped */
+				nd->inode = nd->path.dentry->d_inode;
+				err = link_path_walk(s, nd);
+				if (unlikely(err)) {
 					put_link(nd, &link, cookie);
-					break;
 				} else {
-					if (*s == '/') {
-						if (!nd->root.mnt)
-							set_root(nd);
-						path_put(&nd->path);
-						nd->path = nd->root;
-						path_get(&nd->root);
-						nd->flags |= LOOKUP_JUMPED;
-					}
-					nd->inode = nd->path.dentry->d_inode;
-					err = link_path_walk(s, nd);
-					if (unlikely(err)) {
-						put_link(nd, &link, cookie);
-						break;
-					}
 					err = walk_component(nd, &next, LOOKUP_FOLLOW);
 					put_link(nd, &link, cookie);
+					if (err > 0)
+						goto l;
 				}
-			} while (err > 0);
+			}
 
 			nd->link_count--;
 			nd->depth--;
-- 
2.1.4


  parent reply	other threads:[~2015-04-20 18:17 UTC|newest]

Thread overview: 52+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-04-20 18:12 [RFC][PATCHSET] non-recursive link_path_walk() and reducing stack footprint Al Viro
2015-04-20 18:12 ` [PATCH 01/24] lustre: rip the private symlink nesting limit out Al Viro
2015-04-20 19:08   ` Andreas Dilger
2015-04-20 19:22     ` Al Viro
2015-04-20 20:35       ` Al Viro
2015-04-20 18:12 ` [PATCH 02/24] VFS: replace {, total_}link_count in task_struct with pointer to nameidata Al Viro
2015-04-20 18:12 ` [PATCH 03/24] ovl: rearrange ovl_follow_link to it doesn't need to call ->put_link Al Viro
2015-04-20 18:12 ` [PATCH 04/24] VFS: replace nameidata arg to ->put_link with a char* Al Viro
2015-04-20 18:12 ` [PATCH 05/24] SECURITY: remove nameidata arg from inode_follow_link Al Viro
2015-04-20 18:12 ` [PATCH 06/24] VFS: remove nameidata args from ->follow_link Al Viro
2015-04-20 18:12 ` [PATCH 07/24] namei: expand nested_symlink() in its only caller Al Viro
2015-04-20 18:12 ` [PATCH 08/24] namei.c: separate the parts of follow_link() that find the link body Al Viro
2015-04-20 18:12 ` [PATCH 09/24] namei: fold follow_link() into link_path_walk() Al Viro
2015-04-20 18:12 ` [PATCH 10/24] link_path_walk: handle get_link() returning ERR_PTR() immediately Al Viro
2015-04-20 18:12 ` [PATCH 11/24] link_path_walk: don't bother with walk_component() after jumping link Al Viro
2015-04-20 18:12 ` Al Viro [this message]
2015-04-20 18:12 ` [PATCH 13/24] link_path_walk: massage a bit more Al Viro
2015-04-20 18:12 ` [PATCH 14/24] link_path_walk: get rid of duplication Al Viro
2015-04-20 18:12 ` [PATCH 15/24] link_path_walk: final preparations to killing recursion Al Viro
2015-04-20 18:13 ` [PATCH 16/24] link_path_walk: kill the recursion Al Viro
2015-04-20 21:04   ` Linus Torvalds
2015-04-20 21:32     ` Al Viro
2015-04-20 21:39       ` Linus Torvalds
2015-04-20 21:51         ` Al Viro
2015-04-20 21:41       ` Linus Torvalds
2015-04-20 21:42         ` Linus Torvalds
2015-04-20 21:59           ` Al Viro
2015-04-20 21:52         ` Al Viro
2015-04-20 18:13 ` [PATCH 17/24] link_path_walk: split "return from recursive call" path Al Viro
2015-04-20 18:13 ` [PATCH 18/24] link_path_walk: cleanup - turn goto start; into continue; Al Viro
2015-04-20 18:13 ` [PATCH 19/24] namei: fold may_follow_link() into follow_link() Al Viro
2015-04-20 18:13 ` [PATCH 20/24] namei: introduce nameidata->stack Al Viro
2015-04-20 18:13 ` [PATCH 21/24] namei: regularize use of put_link() and follow_link(), trim arguments Al Viro
2015-04-20 18:13 ` [PATCH 22/24] namei: trim the arguments of get_link() Al Viro
2015-04-20 18:13 ` [PATCH 23/24] new ->follow_link() and ->put_link() calling conventions Al Viro
2015-04-20 18:13 ` [PATCH 24/24] uninline walk_component() Al Viro
2015-04-21 14:49 ` [RFC][PATCHSET] non-recursive link_path_walk() and reducing stack footprint Al Viro
2015-04-21 15:04   ` Christoph Hellwig
2015-04-21 15:12     ` Richard Weinberger
2015-04-21 15:45       ` Al Viro
2015-04-21 16:46         ` Boaz Harrosh
2015-04-21 21:20         ` Al Viro
2015-04-22 18:07           ` Al Viro
2015-04-22 20:12             ` Al Viro
2015-04-22 21:05               ` Al Viro
2015-04-23  7:45                 ` NeilBrown
2015-04-23 18:07                   ` Al Viro
2015-04-24  6:35                     ` NeilBrown
2015-04-24 13:42                       ` Al Viro
2015-05-04  5:11                         ` Al Viro
2015-05-04  7:30                           ` NeilBrown
2015-04-23  5:01           ` Al Viro

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