linux-kernel - [PATCH 1/4] FS-Cache: Increase reference of parent after registering, netfs success

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Message-ID: <20151104152015.2987.68616.stgit@warthog.procyon.org.uk>
Date:	Wed, 04 Nov 2015 15:20:15 +0000
From:	David Howells <dhowells@...hat.com>
To:	viro@...IV.linux.org.uk
Cc:	Kinglong Mee <kinglongmee@...il.com>, linux-nfs@...r.kernel.org,
	linux-kernel@...r.kernel.org, dhowells@...hat.com,
	linux-cachefs@...hat.com, linux-fsdevel@...r.kernel.org
Subject: [PATCH 1/4] FS-Cache: Increase reference of parent after
 registering, netfs success

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

If netfs exist, fscache should not increase the reference of parent's
usage and n_children, otherwise, never be decreased.

v2: thanks David's suggest,
 move increasing reference of parent if success
 use kmem_cache_free() freeing primary_index directly

v3: don't move "netfs->primary_index->parent = &fscache_fsdef_index;"

Signed-off-by: Kinglong Mee <kinglongmee@...il.com>
Signed-off-by: David Howells <dhowells@...hat.com>
---

 fs/fscache/netfs.c |    9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/fs/fscache/netfs.c b/fs/fscache/netfs.c
index 6d941f56faf4..458cc968d9a0 100644
--- a/fs/fscache/netfs.c
+++ b/fs/fscache/netfs.c
@@ -47,9 +47,6 @@ int __fscache_register_netfs(struct fscache_netfs *netfs)
 	netfs->primary_index->netfs_data	= netfs;
 	netfs->primary_index->flags		= 1 << FSCACHE_COOKIE_ENABLED;
 
-	atomic_inc(&netfs->primary_index->parent->usage);
-	atomic_inc(&netfs->primary_index->parent->n_children);
-
 	spin_lock_init(&netfs->primary_index->lock);
 	INIT_HLIST_HEAD(&netfs->primary_index->backing_objects);
 
@@ -62,6 +59,9 @@ 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);
+
 	list_add(&netfs->link, &fscache_netfs_list);
 	ret = 0;
 
@@ -71,8 +71,7 @@ already_registered:
 	up_write(&fscache_addremove_sem);
 
 	if (ret < 0) {
-		netfs->primary_index->parent = NULL;
-		__fscache_cookie_put(netfs->primary_index);
+		kmem_cache_free(fscache_cookie_jar, netfs->primary_index);
 		netfs->primary_index = NULL;
 	}
 

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