[PATCH 3.12 071/142] FS-Cache: Increase reference of parent after registering, netfs success

From: Jiri Slaby
Date: Wed Feb 24 2016 - 05:48:28 EST


From: Kinglong Mee <kinglongmee@xxxxxxxxx>

3.12-stable review patch. If anyone has any objections, please let me know.

===============

commit 86108c2e34a26e4bec3c6ddb23390bf8cedcf391 upstream.

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@xxxxxxxxx>
Signed-off-by: David Howells <dhowells@xxxxxxxxxx>
Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Jiri Slaby <jslaby@xxxxxxx>
---
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 b1bb6117473a..04e18d28013b 100644
--- a/fs/fscache/netfs.c
+++ b/fs/fscache/netfs.c
@@ -46,9 +46,6 @@ int __fscache_register_netfs(struct fscache_netfs *netfs)
netfs->primary_index->parent = &fscache_fsdef_index;
netfs->primary_index->netfs_data = netfs;

- 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);

@@ -61,6 +58,9 @@ 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;
}

--
2.7.1