linux-kernel - [PATCH 3.4 012/125] FS-Cache: Don't override netfs's primary

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Message-Id: <1476275641-4697-12-git-send-email-lizf@kernel.org>
Date:   Wed, 12 Oct 2016 20:32:08 +0800
From:   lizf@...nel.org
To:     stable@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org, Kinglong Mee <kinglongmee@...il.com>,
        David Howells <dhowells@...hat.com>,
        Al Viro <viro@...iv.linux.org.uk>,
        Zefan Li <lizefan@...wei.com>
Subject: [PATCH 3.4 012/125] FS-Cache: Don't override netfs's primary_index if registering failed

From: Kinglong Mee <kinglongmee@...il.com>

3.4.113-rc1 review patch.  If anyone has any objections, please let me know.

------------------


commit b130ed5998e62879a66bad08931a2b5e832da95c upstream.

Only override netfs->primary_index when registering success.

Signed-off-by: Kinglong Mee <kinglongmee@...il.com>
Signed-off-by: David Howells <dhowells@...hat.com>
Signed-off-by: Al Viro <viro@...iv.linux.org.uk>
[lizf: Backported to 3.4: there are no n_active and flags in primary_index]
Signed-off-by: Zefan Li <lizefan@...wei.com>
---
 fs/fscache/netfs.c | 31 +++++++++++++++----------------
 1 file changed, 15 insertions(+), 16 deletions(-)

diff --git a/fs/fscache/netfs.c b/fs/fscache/netfs.c
index 0912b90..6f4e4ed 100644
--- a/fs/fscache/netfs.c
+++ b/fs/fscache/netfs.c
@@ -22,6 +22,7 @@ static LIST_HEAD(fscache_netfs_list);
 int __fscache_register_netfs(struct fscache_netfs *netfs)
 {
 	struct fscache_netfs *ptr;
+	struct fscache_cookie *cookie;
 	int ret;
 
 	_enter("{%s}", netfs->name);
@@ -29,24 +30,23 @@ int __fscache_register_netfs(struct fscache_netfs *netfs)
 	INIT_LIST_HEAD(&netfs->link);
 
 	/* allocate a cookie for the primary index */
-	netfs->primary_index =
-		kmem_cache_zalloc(fscache_cookie_jar, GFP_KERNEL);
+	cookie = kmem_cache_zalloc(fscache_cookie_jar, GFP_KERNEL);
 
-	if (!netfs->primary_index) {
+	if (!cookie) {
 		_leave(" = -ENOMEM");
 		return -ENOMEM;
 	}
 
 	/* initialise the primary index cookie */
-	atomic_set(&netfs->primary_index->usage, 1);
-	atomic_set(&netfs->primary_index->n_children, 0);
+	atomic_set(&cookie->usage, 1);
+	atomic_set(&cookie->n_children, 0);
 
-	netfs->primary_index->def		= &fscache_fsdef_netfs_def;
-	netfs->primary_index->parent		= &fscache_fsdef_index;
-	netfs->primary_index->netfs_data	= netfs;
+	cookie->def		= &fscache_fsdef_netfs_def;
+	cookie->parent		= &fscache_fsdef_index;
+	cookie->netfs_data	= netfs;
 
-	spin_lock_init(&netfs->primary_index->lock);
-	INIT_HLIST_HEAD(&netfs->primary_index->backing_objects);
+	spin_lock_init(&cookie->lock);
+	INIT_HLIST_HEAD(&cookie->backing_objects);
 
 	/* check the netfs type is not already present */
 	down_write(&fscache_addremove_sem);
@@ -57,9 +57,10 @@ int __fscache_register_netfs(struct fscache_netfs *netfs)
 			goto already_registered;
 	}
 
-	atomic_inc(&netfs->primary_index->parent->usage);
-	atomic_inc(&netfs->primary_index->parent->n_children);
+	atomic_inc(&cookie->parent->usage);
+	atomic_inc(&cookie->parent->n_children);
 
+	netfs->primary_index = cookie;
 	list_add(&netfs->link, &fscache_netfs_list);
 	ret = 0;
 
@@ -69,10 +70,8 @@ int __fscache_register_netfs(struct fscache_netfs *netfs)
 already_registered:
 	up_write(&fscache_addremove_sem);
 
-	if (ret < 0) {
-		kmem_cache_free(fscache_cookie_jar, netfs->primary_index);
-		netfs->primary_index = NULL;
-	}
+	if (ret < 0)
+		kmem_cache_free(fscache_cookie_jar, cookie);
 
 	_leave(" = %d", ret);
 	return ret;
-- 
1.9.1