linux-kernel - [PATCH v3 025/110] do_last: regularize the logics around following symlinks

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Message-Id: <1431367690-5223-25-git-send-email-viro@ZenIV.linux.org.uk>
Date:	Mon, 11 May 2015 19:06:45 +0100
From:	Al Viro <viro@...IV.linux.org.uk>
To:	Linus Torvalds <torvalds@...ux-foundation.org>
Cc:	Neil Brown <neilb@...e.de>, Christoph Hellwig <hch@...radead.org>,
	linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org
Subject: [PATCH v3 025/110] do_last: regularize the logics around following symlinks

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

With LOOKUP_FOLLOW we unlazy and return 1; without it we either
fail with ELOOP or, for O_PATH opens, succeed.  No need to mix
those cases...

Signed-off-by: Al Viro <viro@...iv.linux.org.uk>
---
 fs/namei.c | 15 +++++++--------
 1 file changed, 7 insertions(+), 8 deletions(-)

diff --git a/fs/namei.c b/fs/namei.c
index 3e45233..54cbfe7 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -3046,9 +3046,7 @@ retry_lookup:
 		goto out;
 	}
 finish_lookup:
-	/* we _can_ be in RCU mode here */
-	if (should_follow_link(path->dentry,
-			!(open_flag & O_PATH) || (nd->flags & LOOKUP_FOLLOW))) {
+	if (should_follow_link(path->dentry, nd->flags & LOOKUP_FOLLOW)) {
 		if (nd->flags & LOOKUP_RCU) {
 			if (unlikely(nd->path.mnt != path->mnt ||
 				     unlazy_walk(nd, path->dentry))) {
@@ -3057,14 +3055,15 @@ finish_lookup:
 			}
 		}
 		BUG_ON(inode != path->dentry->d_inode);
-		if (!(nd->flags & LOOKUP_FOLLOW)) {
-			path_put_conditional(path, nd);
-			path_put(&nd->path);
-			return -ELOOP;
-		}
 		return 1;
 	}
 
+	if (unlikely(d_is_symlink(path->dentry)) && !(open_flag & O_PATH)) {
+		path_to_nameidata(path, nd);
+		error = -ELOOP;
+		goto out;
+	}
+
 	if ((nd->flags & LOOKUP_RCU) || nd->path.mnt != path->mnt) {
 		path_to_nameidata(path, nd);
 	} else {
-- 
2.1.4

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