Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/sage/ceph-client

Pull ceph fixes from Sage Weil:
 "These fix several bugs with RBD from 3.11 that didn't get tested in
  time for the merge window: some error handling, a use-after-free, and
  a sequencing issue when unmapping and image races with a notify
  operation.

  There is also a patch fixing a problem with the new ceph + fscache
  code that just went in"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/sage/ceph-client:
  fscache: check consistency does not decrement refcount
  rbd: fix error handling from rbd_snap_name()
  rbd: ignore unmapped snapshots that no longer exist
  rbd: fix use-after free of rbd_dev->disk
  rbd: make rbd_obj_notify_ack() synchronous
  rbd: complete notifies before cleaning up osd_client and rbd_dev
  libceph: add function to ensure notifies are complete

1 files changed, 59 insertions, 18 deletions

diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
index b22a7d0fe5b..cb1db2979d3 100644
--- a/drivers/block/rbd.c
+++ b/drivers/block/rbd.c
@@ -931,12 +931,14 @@ static const char *rbd_dev_v1_snap_name(struct rbd_device *rbd_dev,
 					u64 snap_id)
 {
 	u32 which;
+	const char *snap_name;
 
 	which = rbd_dev_snap_index(rbd_dev, snap_id);
 	if (which == BAD_SNAP_INDEX)
-		return NULL;
+		return ERR_PTR(-ENOENT);
 
-	return _rbd_dev_v1_snap_name(rbd_dev, which);
+	snap_name = _rbd_dev_v1_snap_name(rbd_dev, which);
+	return snap_name ? snap_name : ERR_PTR(-ENOMEM);
 }
 
 static const char *rbd_snap_name(struct rbd_device *rbd_dev, u64 snap_id)
@@ -2812,7 +2814,7 @@ out_err:
 	obj_request_done_set(obj_request);
 }
 
-static int rbd_obj_notify_ack(struct rbd_device *rbd_dev, u64 notify_id)
+static int rbd_obj_notify_ack_sync(struct rbd_device *rbd_dev, u64 notify_id)
 {
 	struct rbd_obj_request *obj_request;
 	struct ceph_osd_client *osdc = &rbd_dev->rbd_client->client->osdc;
@@ -2827,16 +2829,17 @@ static int rbd_obj_notify_ack(struct rbd_device *rbd_dev, u64 notify_id)
 	obj_request->osd_req = rbd_osd_req_create(rbd_dev, false, obj_request);
 	if (!obj_request->osd_req)
 		goto out;
-	obj_request->callback = rbd_obj_request_put;
 
 	osd_req_op_watch_init(obj_request->osd_req, 0, CEPH_OSD_OP_NOTIFY_ACK,
 					notify_id, 0, 0);
 	rbd_osd_req_format_read(obj_request);
 
 	ret = rbd_obj_request_submit(osdc, obj_request);
-out:
 	if (ret)
-		rbd_obj_request_put(obj_request);
+		goto out;
+	ret = rbd_obj_request_wait(obj_request);
+out:
+	rbd_obj_request_put(obj_request);
 
 	return ret;
 }
@@ -2856,7 +2859,7 @@ static void rbd_watch_cb(u64 ver, u64 notify_id, u8 opcode, void *data)
 	if (ret)
 		rbd_warn(rbd_dev, "header refresh error (%d)\n", ret);
 
-	rbd_obj_notify_ack(rbd_dev, notify_id);
+	rbd_obj_notify_ack_sync(rbd_dev, notify_id);
 }
 
 /*
@@ -3328,6 +3331,31 @@ static void rbd_exists_validate(struct rbd_device *rbd_dev)
 		clear_bit(RBD_DEV_FLAG_EXISTS, &rbd_dev->flags);
 }
 
+static void rbd_dev_update_size(struct rbd_device *rbd_dev)
+{
+	sector_t size;
+	bool removing;
+
+	/*
+	 * Don't hold the lock while doing disk operations,
+	 * or lock ordering will conflict with the bdev mutex via:
+	 * rbd_add() -> blkdev_get() -> rbd_open()
+	 */
+	spin_lock_irq(&rbd_dev->lock);
+	removing = test_bit(RBD_DEV_FLAG_REMOVING, &rbd_dev->flags);
+	spin_unlock_irq(&rbd_dev->lock);
+	/*
+	 * If the device is being removed, rbd_dev->disk has
+	 * been destroyed, so don't try to update its size
+	 */
+	if (!removing) {
+		size = (sector_t)rbd_dev->mapping.size / SECTOR_SIZE;
+		dout("setting size to %llu sectors", (unsigned long long)size);
+		set_capacity(rbd_dev->disk, size);
+		revalidate_disk(rbd_dev->disk);
+	}
+}
+
 static int rbd_dev_refresh(struct rbd_device *rbd_dev)
 {
 	u64 mapping_size;
@@ -3347,12 +3375,7 @@ static int rbd_dev_refresh(struct rbd_device *rbd_dev)
 	up_write(&rbd_dev->header_rwsem);
 
 	if (mapping_size != rbd_dev->mapping.size) {
-		sector_t size;
-
-		size = (sector_t)rbd_dev->mapping.size / SECTOR_SIZE;
-		dout("setting size to %llu sectors", (unsigned long long)size);
-		set_capacity(rbd_dev->disk, size);
-		revalidate_disk(rbd_dev->disk);
+		rbd_dev_update_size(rbd_dev);
 	}
 
 	return ret;
@@ -4061,8 +4084,13 @@ static u64 rbd_v2_snap_id_by_name(struct rbd_device *rbd_dev, const char *name)
 
 		snap_id = snapc->snaps[which];
 		snap_name = rbd_dev_v2_snap_name(rbd_dev, snap_id);
-		if (IS_ERR(snap_name))
-			break;
+		if (IS_ERR(snap_name)) {
+			/* ignore no-longer existing snapshots */
+			if (PTR_ERR(snap_name) == -ENOENT)
+				continue;
+			else
+				break;
+		}
 		found = !strcmp(name, snap_name);
 		kfree(snap_name);
 	}
@@ -4141,8 +4169,8 @@ static int rbd_dev_spec_update(struct rbd_device *rbd_dev)
 	/* Look up the snapshot name, and make a copy */
 
 	snap_name = rbd_snap_name(rbd_dev, spec->snap_id);
-	if (!snap_name) {
-		ret = -ENOMEM;
+	if (IS_ERR(snap_name)) {
+		ret = PTR_ERR(snap_name);
 		goto out_err;
 	}
 
@@ -5163,10 +5191,23 @@ static ssize_t rbd_remove(struct bus_type *bus,
 	if (ret < 0 || already)
 		return ret;
 
-	rbd_bus_del_dev(rbd_dev);
 	ret = rbd_dev_header_watch_sync(rbd_dev, false);
 	if (ret)
 		rbd_warn(rbd_dev, "failed to cancel watch event (%d)\n", ret);
+
+	/*
+	 * flush remaining watch callbacks - these must be complete
+	 * before the osd_client is shutdown
+	 */
+	dout("%s: flushing notifies", __func__);
+	ceph_osdc_flush_notifies(&rbd_dev->rbd_client->client->osdc);
+	/*
+	 * Don't free anything from rbd_dev->disk until after all
+	 * notifies are completely processed. Otherwise
+	 * rbd_bus_del_dev() will race with rbd_watch_cb(), resulting
+	 * in a potential use after free of rbd_dev->disk or rbd_dev.
+	 */
+	rbd_bus_del_dev(rbd_dev);
 	rbd_dev_image_release(rbd_dev);
 	module_put(THIS_MODULE);