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authorDavid Howells <dhowells@redhat.com>2014-02-17 15:01:47 +0000
committerLinus Torvalds <torvalds@linux-foundation.org>2014-02-17 13:47:35 -0800
commit7026f1929e18921fd67bf478f475a8fdfdff16ae (patch)
treebddfd52b6d380a6620b6fd0703ae6230168d3a6d /fs/fscache
parent416e2abd925d0f41dc877d1fe01489d79bdecf4c (diff)
FS-Cache: Handle removal of unadded object to the fscache_object_list rb tree
When FS-Cache allocates an object, the following sequence of events can occur: -->fscache_alloc_object() -->cachefiles_alloc_object() [via cache->ops->alloc_object] <--[returns new object] -->fscache_attach_object() <--[failed] -->cachefiles_put_object() [via cache->ops->put_object] -->fscache_object_destroy() -->fscache_objlist_remove() -->rb_erase() to remove the object from fscache_object_list. resulting in a crash in the rbtree code. The problem is that the object is only added to fscache_object_list on the success path of fscache_attach_object() where it calls fscache_objlist_add(). So if fscache_attach_object() fails, the object won't have been added to the objlist rbtree. We do, however, unconditionally try to remove the object from the tree. Thanks to NeilBrown for finding this and suggesting this solution. Reported-by: NeilBrown <neilb@suse.de> Signed-off-by: David Howells <dhowells@redhat.com> Tested-by: (a customer of) NeilBrown <neilb@suse.de> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs/fscache')
-rw-r--r--fs/fscache/object-list.c5
-rw-r--r--fs/fscache/object.c3
2 files changed, 8 insertions, 0 deletions
diff --git a/fs/fscache/object-list.c b/fs/fscache/object-list.c
index e1959efad64f..b5ebc2d7d80d 100644
--- a/fs/fscache/object-list.c
+++ b/fs/fscache/object-list.c
@@ -50,6 +50,8 @@ void fscache_objlist_add(struct fscache_object *obj)
struct fscache_object *xobj;
struct rb_node **p = &fscache_object_list.rb_node, *parent = NULL;
+ ASSERT(RB_EMPTY_NODE(&obj->objlist_link));
+
write_lock(&fscache_object_list_lock);
while (*p) {
@@ -75,6 +77,9 @@ void fscache_objlist_add(struct fscache_object *obj)
*/
void fscache_objlist_remove(struct fscache_object *obj)
{
+ if (RB_EMPTY_NODE(&obj->objlist_link))
+ return;
+
write_lock(&fscache_object_list_lock);
BUG_ON(RB_EMPTY_ROOT(&fscache_object_list));
diff --git a/fs/fscache/object.c b/fs/fscache/object.c
index 53d35c504240..d3b4539f1651 100644
--- a/fs/fscache/object.c
+++ b/fs/fscache/object.c
@@ -314,6 +314,9 @@ void fscache_object_init(struct fscache_object *object,
object->cache = cache;
object->cookie = cookie;
object->parent = NULL;
+#ifdef CONFIG_FSCACHE_OBJECT_LIST
+ RB_CLEAR_NODE(&object->objlist_link);
+#endif
object->oob_event_mask = 0;
for (t = object->oob_table; t->events; t++)