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-rw-r--r--fs/cachefiles/rdwr.c17
1 files changed, 12 insertions, 5 deletions
diff --git a/fs/cachefiles/rdwr.c b/fs/cachefiles/rdwr.c
index 5082c8a49686..40f7595aad10 100644
--- a/fs/cachefiles/rdwr.c
+++ b/fs/cachefiles/rdwr.c
@@ -27,6 +27,7 @@ static int cachefiles_read_waiter(wait_queue_entry_t *wait, unsigned mode,
struct cachefiles_one_read *monitor =
container_of(wait, struct cachefiles_one_read, monitor);
struct cachefiles_object *object;
+ struct fscache_retrieval *op = monitor->op;
struct wait_bit_key *key = _key;
struct page *page = wait->private;
@@ -51,16 +52,22 @@ static int cachefiles_read_waiter(wait_queue_entry_t *wait, unsigned mode,
list_del(&wait->entry);
/* move onto the action list and queue for FS-Cache thread pool */
- ASSERT(monitor->op);
+ ASSERT(op);
- object = container_of(monitor->op->op.object,
- struct cachefiles_object, fscache);
+ /* We need to temporarily bump the usage count as we don't own a ref
+ * here otherwise cachefiles_read_copier() may free the op between the
+ * monitor being enqueued on the op->to_do list and the op getting
+ * enqueued on the work queue.
+ */
+ fscache_get_retrieval(op);
+ object = container_of(op->op.object, struct cachefiles_object, fscache);
spin_lock(&object->work_lock);
- list_add_tail(&monitor->op_link, &monitor->op->to_do);
+ list_add_tail(&monitor->op_link, &op->to_do);
spin_unlock(&object->work_lock);
- fscache_enqueue_retrieval(monitor->op);
+ fscache_enqueue_retrieval(op);
+ fscache_put_retrieval(op);
return 0;
}