Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754583AbbEKSSB (ORCPT ); Mon, 11 May 2015 14:18:01 -0400 Received: from zeniv.linux.org.uk ([195.92.253.2]:47488 "EHLO ZenIV.linux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755032AbbEKSI2 (ORCPT ); Mon, 11 May 2015 14:08:28 -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 089/110] namei: lift link_path_walk() call out of trailing_symlink() Date: Mon, 11 May 2015 19:07:49 +0100 Message-Id: <1431367690-5223-89-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: 3243 Lines: 124 From: Al Viro Make trailing_symlink() return the pathname to traverse or ERR_PTR(-E...). A subtle point is that for "magic" symlinks it returns "" now - that leads to link_path_walk("", nd), which is immediately returning 0 and we are back to the treatment of the last component, at whereever the damn thing has left us. Reduces the stack footprint - link_path_walk() called on more shallow stack now. Signed-off-by: Al Viro --- fs/namei.c | 50 +++++++++++++++++++++++--------------------------- 1 file changed, 23 insertions(+), 27 deletions(-) diff --git a/fs/namei.c b/fs/namei.c index 06c7120..46f4266 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -1970,24 +1970,24 @@ static void path_cleanup(struct nameidata *nd) } } -static int trailing_symlink(struct nameidata *nd) +static const char *trailing_symlink(struct nameidata *nd) { const char *s; int error = may_follow_link(nd); if (unlikely(error)) { terminate_walk(nd); - return error; + return ERR_PTR(error); } nd->flags |= LOOKUP_PARENT; nd->stack[0].name = NULL; s = get_link(nd); if (unlikely(IS_ERR(s))) { terminate_walk(nd); - return PTR_ERR(s); + return s; } if (unlikely(!s)) - return 0; - return link_path_walk(s, nd); + s = ""; + return s; } static inline int lookup_last(struct nameidata *nd) @@ -2017,12 +2017,12 @@ static int path_lookupat(int dfd, const struct filename *name, if (IS_ERR(s)) return PTR_ERR(s); - err = link_path_walk(s, nd); - if (!err) { - while ((err = lookup_last(nd)) > 0) { - err = trailing_symlink(nd); - if (err) - break; + while (!(err = link_path_walk(s, nd)) + && ((err = lookup_last(nd)) > 0)) { + s = trailing_symlink(nd); + if (IS_ERR(s)) { + err = PTR_ERR(s); + break; } } @@ -2401,16 +2401,14 @@ path_mountpoint(int dfd, const struct filename *name, struct path *path, int err; if (IS_ERR(s)) return PTR_ERR(s); - err = link_path_walk(s, nd); - if (unlikely(err)) - goto out; - - while ((err = mountpoint_last(nd, path)) > 0) { - err = trailing_symlink(nd); - if (err) + while (!(err = link_path_walk(s, nd)) && + (err = mountpoint_last(nd, path)) > 0) { + s = trailing_symlink(nd); + if (IS_ERR(s)) { + err = PTR_ERR(s); break; + } } -out: path_cleanup(nd); return err; } @@ -3282,17 +3280,15 @@ static struct file *path_openat(int dfd, struct filename *pathname, put_filp(file); return ERR_CAST(s); } - error = link_path_walk(s, nd); - if (unlikely(error)) - goto out; - - while ((error = do_last(nd, file, op, &opened, pathname)) > 0) { + while (!(error = link_path_walk(s, nd)) && + (error = do_last(nd, file, op, &opened, pathname)) > 0) { nd->flags &= ~(LOOKUP_OPEN|LOOKUP_CREATE|LOOKUP_EXCL); - error = trailing_symlink(nd); - if (unlikely(error)) + s = trailing_symlink(nd); + if (IS_ERR(s)) { + error = PTR_ERR(s); break; + } } -out: path_cleanup(nd); out2: if (!(opened & FILE_OPENED)) { -- 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/