rbd: define rbd_dev_unprobe()

Define a new function rbd_dev_unprobe() which undoes state changes
that occur from calling rbd_dev_v1_probe() or rbd_dev_v2_probe().
Note that this is a superset of rbd_header_free(), which is now
getting removed (it seems to have been used improperly anyway).

Flesh out rbd_dev_image_release() so it undoes exactly what
rbd_dev_image_probe() does.

This means that:
    - rbd_dev_device_release() gets called when the last device
      reference gets dropped;
    - that undoes everything done by the rbd_dev_device_setup() call
      at the end of rbd_dev_image_probe() (and nothing more), ending
      by calling rbd_dev_image_release(); and
    - rbd_dev_image_release() undoes everything else done by
      rbd_dev_image_probe() (and this includes a call to
      rbd_dev_unprobe().

This means the image and device portions of an rbd device are fairly
cleanly separated now, so error paths should be a little easier to
verify than they used to be.

Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>

diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
index feaa2e9192a1ad285df80d41f2d2ba4c508991af..408e29f102c8237754d70685bce961cc9bdad5ec 100644 (file)
--- a/drivers/block/rbd.c
+++ b/drivers/block/rbd.c
@@ -900,18 +900,6 @@ static void rbd_dev_clear_mapping(struct rbd_device *rbd_dev)
        rbd_dev->mapping.read_only = true;
 }
 
-static void rbd_header_free(struct rbd_image_header *header)
-{
-       kfree(header->object_prefix);
-       header->object_prefix = NULL;
-       kfree(header->snap_sizes);
-       header->snap_sizes = NULL;
-       kfree(header->snap_names);
-       header->snap_names = NULL;
-       rbd_snap_context_put(header->snapc);
-       header->snapc = NULL;
-}
-
 static const char *rbd_segment_name(struct rbd_device *rbd_dev, u64 offset)
 {
        char *name;
@@ -4588,6 +4576,27 @@ out:
        return ret;
 }
 
+/* Undo whatever state changes are made by v1 or v2 image probe */
+
+static void rbd_dev_unprobe(struct rbd_device *rbd_dev)
+{
+       struct rbd_image_header *header;
+
+       rbd_dev_remove_parent(rbd_dev);
+       rbd_spec_put(rbd_dev->parent_spec);
+       rbd_dev->parent_spec = NULL;
+       rbd_dev->parent_overlap = 0;
+
+       /* Free dynamic fields from the header, then zero it out */
+
+       header = &rbd_dev->header;
+       rbd_snap_context_put(header->snapc);
+       kfree(header->snap_sizes);
+       kfree(header->snap_names);
+       kfree(header->object_prefix);
+       memset(header, 0, sizeof (*header));
+}
+
 static int rbd_dev_v1_probe(struct rbd_device *rbd_dev)
 {
        int ret;
@@ -4809,10 +4818,19 @@ static int rbd_dev_header_name(struct rbd_device *rbd_dev)
 
 static void rbd_dev_image_release(struct rbd_device *rbd_dev)
 {
-       rbd_header_free(&rbd_dev->header);
-       rbd_assert(rbd_dev->rbd_client != NULL);
-       rbd_spec_put(rbd_dev->parent_spec);
+       int ret;
+
+       rbd_remove_all_snaps(rbd_dev);
+       rbd_dev_unprobe(rbd_dev);
+       ret = rbd_dev_header_watch_sync(rbd_dev, 0);
+       if (ret)
+               rbd_warn(rbd_dev, "failed to cancel watch event (%d)\n", ret);
        kfree(rbd_dev->header_name);
+       rbd_dev->header_name = NULL;
+       rbd_dev->image_format = 0;
+       kfree(rbd_dev->spec->image_id);
+       rbd_dev->spec->image_id = NULL;
+
        rbd_dev_destroy(rbd_dev);
 }
 
@@ -4854,7 +4872,7 @@ static int rbd_dev_image_probe(struct rbd_device *rbd_dev)
 
        ret = rbd_dev_snaps_update(rbd_dev);
        if (ret)
-               goto err_out_watch;
+               goto err_out_probe;
 
        ret = rbd_dev_spec_update(rbd_dev);
        if (ret)
@@ -4865,15 +4883,13 @@ static int rbd_dev_image_probe(struct rbd_device *rbd_dev)
                goto err_out_snaps;
 
        ret = rbd_dev_device_setup(rbd_dev);
-       if (ret)
-               goto err_out_parent;
+       if (!ret)
+               return 0;
 
-       return ret;
-err_out_parent:
-       rbd_dev_remove_parent(rbd_dev);
-       rbd_header_free(&rbd_dev->header);
 err_out_snaps:
        rbd_remove_all_snaps(rbd_dev);
+err_out_probe:
+       rbd_dev_unprobe(rbd_dev);
 err_out_watch:
        tmp = rbd_dev_header_watch_sync(rbd_dev, 0);
        if (tmp)
@@ -5005,7 +5021,6 @@ static void rbd_dev_remove_parent(struct rbd_device *rbd_dev)
                struct rbd_device *first = rbd_dev;
                struct rbd_device *second = first->parent;
                struct rbd_device *third;
-               int ret;
 
                /*
                 * Follow to the parent with no grandparent and
@@ -5016,11 +5031,6 @@ static void rbd_dev_remove_parent(struct rbd_device *rbd_dev)
                        second = third;
                }
                rbd_assert(second);
-               ret = rbd_dev_header_watch_sync(rbd_dev, 0);
-               if (ret)
-                       rbd_warn(rbd_dev,
-                               "failed to cancel watch event (%d)\n", ret);
-               rbd_remove_all_snaps(second);
                rbd_bus_del_dev(second);
                first->parent = NULL;
                first->parent_overlap = 0;
@@ -5065,19 +5075,7 @@ static ssize_t rbd_remove(struct bus_type *bus,
        spin_unlock_irq(&rbd_dev->lock);
        if (ret < 0)
                goto done;
-
-       ret = rbd_dev_header_watch_sync(rbd_dev, 0);
-       if (ret) {
-               rbd_warn(rbd_dev, "failed to cancel watch event (%d)\n", ret);
-               clear_bit(RBD_DEV_FLAG_REMOVING, &rbd_dev->flags);
-               smp_mb();
-               return ret;
-       }
        ret = count;
-
-       rbd_dev_remove_parent(rbd_dev);
-
-       rbd_remove_all_snaps(rbd_dev);
        rbd_bus_del_dev(rbd_dev);
        module_put(THIS_MODULE);
 done: