A set of patches for a deadlock on "rbd map" error path and a fix

for invalid pointer dereference and uninitialized variable use on
 asynchronous create and unlink error paths.
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Merge tag 'ceph-for-5.7-rc2' of git://github.com/ceph/ceph-client

Pull ceph fixes from Ilya Dryomov:

 - a set of patches for a deadlock on "rbd map" error path

 - a fix for invalid pointer dereference and uninitialized variable use
   on asynchronous create and unlink error paths.

* tag 'ceph-for-5.7-rc2' of git://github.com/ceph/ceph-client:
  ceph: fix potential bad pointer deref in async dirops cb's
  rbd: don't mess with a page vector in rbd_notify_op_lock()
  rbd: don't test rbd_dev->opts in rbd_dev_image_release()
  rbd: call rbd_dev_unprobe() after unwatching and flushing notifies
  rbd: avoid a deadlock on header_rwsem when flushing notifies

drivers/block/rbd.c

@@ -3754,11 +3754,7 @@ static int __rbd_notify_op_lock(struct rbd_device *rbd_dev,
 static void rbd_notify_op_lock(struct rbd_device *rbd_dev,
 			       enum rbd_notify_op notify_op)
 {
-	struct page **reply_pages;
+	__rbd_notify_op_lock(rbd_dev, notify_op, NULL, NULL);
-	size_t reply_len;
-
-	__rbd_notify_op_lock(rbd_dev, notify_op, &reply_pages, &reply_len);
-	ceph_release_page_vector(reply_pages, calc_pages_for(0, reply_len));
 }
 
 static void rbd_notify_acquired_lock(struct work_struct *work)
@@ -4527,6 +4523,10 @@ static void cancel_tasks_sync(struct rbd_device *rbd_dev)
 	cancel_work_sync(&rbd_dev->unlock_work);
 }
 
+/*
+ * header_rwsem must not be held to avoid a deadlock with
+ * rbd_dev_refresh() when flushing notifies.
+ */
 static void rbd_unregister_watch(struct rbd_device *rbd_dev)
 {
 	cancel_tasks_sync(rbd_dev);
@@ -6894,9 +6894,10 @@ static void rbd_print_dne(struct rbd_device *rbd_dev, bool is_snap)
 
 static void rbd_dev_image_release(struct rbd_device *rbd_dev)
 {
-	rbd_dev_unprobe(rbd_dev);
+	if (!rbd_is_ro(rbd_dev))
-	if (rbd_dev->opts)
 		rbd_unregister_watch(rbd_dev);
+
+	rbd_dev_unprobe(rbd_dev);
 	rbd_dev->image_format = 0;
 	kfree(rbd_dev->spec->image_id);
 	rbd_dev->spec->image_id = NULL;
@@ -6907,6 +6908,9 @@ static void rbd_dev_image_release(struct rbd_device *rbd_dev)
  * device.  If this image is the one being mapped (i.e., not a
  * parent), initiate a watch on its header object before using that
  * object to get detailed information about the rbd image.
+ *
+ * On success, returns with header_rwsem held for write if called
+ * with @depth == 0.
  */
 static int rbd_dev_image_probe(struct rbd_device *rbd_dev, int depth)
 {
@@ -6936,11 +6940,14 @@ static int rbd_dev_image_probe(struct rbd_device *rbd_dev, int depth)
 		}
 	}
 
+	if (!depth)
+		down_write(&rbd_dev->header_rwsem);
+
 	ret = rbd_dev_header_info(rbd_dev);
 	if (ret) {
 		if (ret == -ENOENT && !need_watch)
 			rbd_print_dne(rbd_dev, false);
-		goto err_out_watch;
+		goto err_out_probe;
 	}
 
 	/*
@@ -6985,10 +6992,11 @@ static int rbd_dev_image_probe(struct rbd_device *rbd_dev, int depth)
 	return 0;
 
 err_out_probe:
-	rbd_dev_unprobe(rbd_dev);
+	if (!depth)
-err_out_watch:
+		up_write(&rbd_dev->header_rwsem);
 	if (need_watch)
 		rbd_unregister_watch(rbd_dev);
+	rbd_dev_unprobe(rbd_dev);
 err_out_format:
 	rbd_dev->image_format = 0;
 	kfree(rbd_dev->spec->image_id);
@@ -7050,12 +7058,9 @@ static ssize_t do_rbd_add(struct bus_type *bus,
 		goto err_out_rbd_dev;
 	}
 
-	down_write(&rbd_dev->header_rwsem);
 	rc = rbd_dev_image_probe(rbd_dev, 0);
-	if (rc < 0) {
+	if (rc < 0)
-		up_write(&rbd_dev->header_rwsem);
 		goto err_out_rbd_dev;
-	}
 
 	if (rbd_dev->opts->alloc_size > rbd_dev->layout.object_size) {
 		rbd_warn(rbd_dev, "alloc_size adjusted to %u",

fs/ceph/dir.c

@@ -1051,8 +1051,8 @@ static void ceph_async_unlink_cb(struct ceph_mds_client *mdsc,
 
 	/* If op failed, mark everyone involved for errors */
 	if (result) {
-		int pathlen;
+		int pathlen = 0;
-		u64 base;
+		u64 base = 0;
 		char *path = ceph_mdsc_build_path(req->r_dentry, &pathlen,
 						  &base, 0);
 

fs/ceph/file.c

@@ -527,8 +527,8 @@ static void ceph_async_create_cb(struct ceph_mds_client *mdsc,
 
 	if (result) {
 		struct dentry *dentry = req->r_dentry;
-		int pathlen;
+		int pathlen = 0;
-		u64 base;
+		u64 base = 0;
 		char *path = ceph_mdsc_build_path(req->r_dentry, &pathlen,
 						  &base, 0);
 

fs/ceph/mds_client.h

@@ -521,7 +521,7 @@ extern void ceph_mdsc_pre_umount(struct ceph_mds_client *mdsc);
 
 static inline void ceph_mdsc_free_path(char *path, int len)
 {
-	if (path)
+	if (!IS_ERR_OR_NULL(path))
 		__putname(path - (PATH_MAX - 1 - len));
 }