linux-kernel - [PATCH 77/79] namei: move unlazying on symlinks towards get

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Date:	Tue,  5 May 2015 06:22:51 +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 77/79] namei: move unlazying on symlinks towards get_link() call sites

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

Signed-off-by: Al Viro <viro@...iv.linux.org.uk>
---
 fs/namei.c | 45 +++++++++++++++++++++++++++++++++------------
 1 file changed, 33 insertions(+), 12 deletions(-)

diff --git a/fs/namei.c b/fs/namei.c
index 98e932c..eb3f7d9 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -538,10 +538,18 @@ static void restore_nameidata(struct nameidata *old)
 
 static int __nd_alloc_stack(struct nameidata *nd)
 {
-	struct saved *p = kmalloc(MAXSYMLINKS * sizeof(struct saved),
-				  GFP_KERNEL);
-	if (unlikely(!p))
-		return -ENOMEM;
+	struct saved *p;
+	if (nd->flags & LOOKUP_RCU) {
+		p = kmalloc(MAXSYMLINKS * sizeof(struct saved),
+				GFP_ATOMIC);
+		if (unlikely(!p))
+			return -ECHILD;
+	} else {
+		p = kmalloc(MAXSYMLINKS * sizeof(struct saved),
+				GFP_KERNEL);
+		if (unlikely(!p))
+			return -ENOMEM;
+	}
 	memcpy(p, nd->internal, sizeof(nd->internal));
 	nd->stack = p;
 	return 0;
@@ -1561,12 +1569,6 @@ static int pick_link(struct nameidata *nd, struct path *link)
 		path_to_nameidata(link, nd);
 		return -ELOOP;
 	}
-	if (nd->flags & LOOKUP_RCU) {
-		if (unlikely(nd->path.mnt != link->mnt ||
-			     unlazy_walk(nd, link->dentry))) {
-			return -ECHILD;
-		}
-	}
 	error = nd_alloc_stack(nd);
 	if (unlikely(error)) {
 		path_to_nameidata(link, nd);
@@ -1839,7 +1841,17 @@ OK:
 			break;
 
 		if (err) {
-			const char *s = get_link(nd);
+			const char *s;
+
+			if (nd->flags & LOOKUP_RCU) {
+				if (unlikely(nd->link.mnt != nd->path.mnt ||
+					     unlazy_walk(nd, nd->link.dentry))) {
+					err = -ECHILD;
+					break;
+				}
+			}
+
+			s = get_link(nd);
 
 			if (unlikely(IS_ERR(s))) {
 				err = PTR_ERR(s);
@@ -1992,7 +2004,16 @@ static void path_cleanup(struct nameidata *nd)
 static int trailing_symlink(struct nameidata *nd)
 {
 	const char *s;
-	int error = may_follow_link(&nd->link, nd);
+	int error;
+
+	if (nd->flags & LOOKUP_RCU) {
+		if (unlikely(nd->link.mnt != nd->path.mnt ||
+			     unlazy_walk(nd, nd->link.dentry))) {
+			terminate_walk(nd);
+			return -ECHILD;
+		}
+	}
+	error = may_follow_link(&nd->link, nd);
 	if (unlikely(error))
 		return error;
 	nd->flags |= LOOKUP_PARENT;
-- 
2.1.4

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