X-Git-Url: https://git.proxmox.com/?a=blobdiff_plain;f=fs%2Fcachefiles%2Frdwr.c;h=4d03a0c93edaa46146754a611c3849392a884e6f;hb=15c47ccdc31c6327d745eee1d8597f9886441430;hp=883bc7bb12c5625ffa3698dcc0dce40a13c3c3cf;hpb=ce44cd8dfc55110fa7423ceb47a8a70dac65fe89;p=mirror_ubuntu-bionic-kernel.git

diff --git a/fs/cachefiles/rdwr.c b/fs/cachefiles/rdwr.c
index 883bc7bb12c5..4d03a0c93eda 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;
 }
 
@@ -504,6 +511,8 @@ static int cachefiles_read_backing_file(struct cachefiles_object *object,
 				goto installed_new_backing_page;
 			if (ret != -EEXIST)
 				goto nomem;
+			put_page(newpage);
+			newpage = NULL;
 		}
 
 		/* we've installed a new backing page, so now we need
@@ -528,7 +537,10 @@ static int cachefiles_read_backing_file(struct cachefiles_object *object,
 					    netpage->index, cachefiles_gfp);
 		if (ret < 0) {
 			if (ret == -EEXIST) {
+				put_page(backpage);
+				backpage = NULL;
 				put_page(netpage);
+				netpage = NULL;
 				fscache_retrieval_complete(op, 1);
 				continue;
 			}
@@ -601,7 +613,10 @@ static int cachefiles_read_backing_file(struct cachefiles_object *object,
 					    netpage->index, cachefiles_gfp);
 		if (ret < 0) {
 			if (ret == -EEXIST) {
+				put_page(backpage);
+				backpage = NULL;
 				put_page(netpage);
+				netpage = NULL;
 				fscache_retrieval_complete(op, 1);
 				continue;
 			}