Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932973AbbEKScy (ORCPT ); Mon, 11 May 2015 14:32:54 -0400 Received: from zeniv.linux.org.uk ([195.92.253.2]:47138 "EHLO ZenIV.linux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754957AbbEKSIU (ORCPT ); Mon, 11 May 2015 14:08:20 -0400 From: Al Viro To: Linus Torvalds Cc: Neil Brown , Christoph Hellwig , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org Subject: [PATCH v3 044/110] link_path_walk: kill the recursion Date: Mon, 11 May 2015 19:07:04 +0100 Message-Id: <1431367690-5223-44-git-send-email-viro@ZenIV.linux.org.uk> X-Mailer: git-send-email 1.7.7.6 In-Reply-To: <20150511180650.GA4147@ZenIV.linux.org.uk> References: <20150511180650.GA4147@ZenIV.linux.org.uk> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2930 Lines: 122 From: Al Viro absolutely straightforward now - the only variables we need to preserve across the recursive call are name, link and cookie, and recursion depth is limited (and can is equal to nd->depth). So arrange an array of triples to hold instances of those and be done with that. Signed-off-by: Al Viro --- fs/namei.c | 40 +++++++++++++++++++++++++++++----------- 1 file changed, 29 insertions(+), 11 deletions(-) diff --git a/fs/namei.c b/fs/namei.c index b469ce2..9844bb2 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -1711,8 +1711,14 @@ static inline u64 hash_name(const char *name) */ static int link_path_walk(const char *name, struct nameidata *nd) { + struct saved { + struct path link; + void *cookie; + const char *name; + } stack[MAX_NESTED_LINKS], *last = stack + nd->depth - 1; int err; - + +start: while (*name=='/') name++; if (!*name) @@ -1776,8 +1782,6 @@ Walked: goto Err; if (err) { - struct path link; - void *cookie; const char *s; if (unlikely(current->link_count >= MAX_NESTED_LINKS)) { @@ -1790,22 +1794,25 @@ Walked: nd->depth++; current->link_count++; + last++; - link = nd->link; - s = get_link(&link, nd, &cookie); + last->link = nd->link; + s = get_link(&last->link, nd, &last->cookie); if (unlikely(IS_ERR(s))) { err = PTR_ERR(s); current->link_count--; nd->depth--; + last--; goto Err; } err = 0; if (unlikely(!s)) { /* jumped */ - put_link(nd, &link, cookie); + put_link(nd, &last->link, last->cookie); current->link_count--; nd->depth--; + last--; } else { if (*s == '/') { if (!nd->root.mnt) @@ -1816,17 +1823,24 @@ Walked: nd->flags |= LOOKUP_JUMPED; } nd->inode = nd->path.dentry->d_inode; - err = link_path_walk(s, nd); + last->name = name; + name = s; + goto start; + +back: + name = last->name; if (unlikely(err)) { - put_link(nd, &link, cookie); + put_link(nd, &last->link, last->cookie); current->link_count--; nd->depth--; + last--; goto Err; } else { err = walk_component(nd, LOOKUP_FOLLOW); - put_link(nd, &link, cookie); + put_link(nd, &last->link, last->cookie); current->link_count--; nd->depth--; + last--; goto Walked; } } @@ -1838,9 +1852,13 @@ Walked: } terminate_walk(nd); Err: - return err; + if (likely(!nd->depth)) + return err; + goto back; OK: - return 0; + if (likely(!nd->depth)) + return 0; + goto back; } static int path_init(int dfd, const struct filename *name, unsigned int flags, -- 2.1.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/