[PATCH 3.14 74/76] FS-Cache: Increase reference of parent after registering, netfs success

From: Greg Kroah-Hartman
Date: Sun Feb 14 2016 - 18:08:17 EST


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

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

From: Kinglong Mee <kinglongmee@xxxxxxxxx>

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: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

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

--- a/fs/fscache/netfs.c
+++ b/fs/fscache/netfs.c
@@ -47,9 +47,6 @@ int __fscache_register_netfs(struct fsca
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 fsca
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;

@@ -72,8 +72,7 @@ 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;
}