[PATCH 2/4, v2] rbd: define rbd_dev_v2_refresh()

[Alex Elder <elder@inktank.com>]

Define a new function rbd_dev_v2_refresh() to update/refresh the
snapshot context for a format version 2 rbd image.  This function
will update anything that is not fixed for the life of an rbd
image--at the moment this is mainly the snapshot context and (for
a base mapping) the size.

Update rbd_refresh_header() so it selects which function to use
based on the image format.

Rename __rbd_refresh_header() to be rbd_dev_v1_refresh()
to be consistent with the naming of its version 2 counterpart.
Similarly rename rbd_refresh_header() to be rbd_dev_refresh().

Unrelated--we use rbd_image_format_valid() here.  Delete the other
use of it, which was primarily put in place to ensure that function
was referenced at the time it was defined.

Signed-off-by: Alex Elder <elder@inktank.com>
---
Changes in v2:
     - also fetch size when refereshing image
     - drop "snapc" from refresh function names
  drivers/block/rbd.c |   55 
+++++++++++++++++++++++++++++++++++++++++++--------
  1 file changed, 47 insertions(+), 8 deletions(-)

diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
index d36e6d7..23f3beb 100644
--- a/drivers/block/rbd.c
+++ b/drivers/block/rbd.c
@@ -268,7 +268,8 @@ static void rbd_put_dev(struct rbd_device *rbd_dev)
  	put_device(&rbd_dev->dev);
  }

-static int rbd_refresh_header(struct rbd_device *rbd_dev, u64 *hver);
+static int rbd_dev_refresh(struct rbd_device *rbd_dev, u64 *hver);
+static int rbd_dev_v2_refresh(struct rbd_device *rbd_dev, u64 *hver);

  static int rbd_open(struct block_device *bdev, fmode_t mode)
  {
@@ -1304,7 +1305,7 @@ static void rbd_watch_cb(u64 ver, u64 notify_id, 
u8 opcode, void *data)
  	dout("rbd_watch_cb %s notify_id=%llu opcode=%u\n",
  		rbd_dev->header_name, (unsigned long long) notify_id,
  		(unsigned int) opcode);
-	rc = rbd_refresh_header(rbd_dev, &hver);
+	rc = rbd_dev_refresh(rbd_dev, &hver);
  	if (rc)
  		pr_warning(RBD_DRV_NAME "%d got notification but failed to "
  			   " update snaps: %d\n", rbd_dev->major, rc);
@@ -1729,7 +1730,7 @@ static void rbd_update_size(struct rbd_device 
*rbd_dev)
  /*
   * only read the first part of the ondisk header, without the snaps info
   */
-static int __rbd_refresh_header(struct rbd_device *rbd_dev, u64 *hver)
+static int rbd_dev_v1_refresh(struct rbd_device *rbd_dev, u64 *hver)
  {
  	int ret;
  	struct rbd_image_header h;
@@ -1772,12 +1773,16 @@ static int __rbd_refresh_header(struct 
rbd_device *rbd_dev, u64 *hver)
  	return ret;
  }

-static int rbd_refresh_header(struct rbd_device *rbd_dev, u64 *hver)
+static int rbd_dev_refresh(struct rbd_device *rbd_dev, u64 *hver)
  {
  	int ret;

+	rbd_assert(rbd_image_format_valid(rbd_dev->image_format));
  	mutex_lock_nested(&ctl_mutex, SINGLE_DEPTH_NESTING);
-	ret = __rbd_refresh_header(rbd_dev, hver);
+	if (rbd_dev->image_format == 1)
+		ret = rbd_dev_v1_refresh(rbd_dev, hver);
+	else
+		ret = rbd_dev_v2_refresh(rbd_dev, hver);
  	mutex_unlock(&ctl_mutex);

  	return ret;
@@ -1937,7 +1942,7 @@ static ssize_t rbd_image_refresh(struct device *dev,
  	struct rbd_device *rbd_dev = dev_to_rbd_dev(dev);
  	int ret;

-	ret = rbd_refresh_header(rbd_dev, NULL);
+	ret = rbd_dev_refresh(rbd_dev, NULL);

  	return ret < 0 ? ret : size;
  }
@@ -2401,6 +2406,41 @@ static char *rbd_dev_snap_info(struct rbd_device 
*rbd_dev, u32 which,
  	return ERR_PTR(-EINVAL);
  }

+static int rbd_dev_v2_refresh(struct rbd_device *rbd_dev, u64 *hver)
+{
+	int ret;
+	__u8 obj_order;
+	u64 image_size;
+
+	down_write(&rbd_dev->header_rwsem);
+
+	/* Grab old values first, to see if they change */
+
+	obj_order = rbd_dev->header.obj_order,
+	image_size = rbd_dev->header.image_size;
+	ret = rbd_dev_v2_image_size(rbd_dev);
+	if (ret)
+		goto out;
+	rbd_assert(rbd_dev->header.obj_order == obj_order);
+	if (image_size != rbd_dev->header.image_size)
+		rbd_update_size(rbd_dev);
+
+	ret = rbd_dev_v2_snap_context(rbd_dev, hver);
+	dout("rbd_dev_v2_snap_context returned %d\n", ret);
+	if (ret)
+		goto out;
+	ret = rbd_dev_snaps_update(rbd_dev);
+	dout("rbd_dev_snaps_update returned %d\n", ret);
+	if (ret)
+		goto out;
+	ret = rbd_dev_snaps_register(rbd_dev);
+	dout("rbd_dev_snaps_register returned %d\n", ret);
+out:
+	up_write(&rbd_dev->header_rwsem);
+
+	return 0;
+}
+
  /*
   * Scan the rbd device's current snapshot list and compare it to the
   * newly-received snapshot context.  Remove any existing snapshots
@@ -2563,7 +2603,7 @@ static int rbd_init_watch_dev(struct rbd_device 
*rbd_dev)
  	do {
  		ret = rbd_req_sync_watch(rbd_dev);
  		if (ret == -ERANGE) {
-			rc = rbd_refresh_header(rbd_dev, NULL);
+			rc = rbd_dev_refresh(rbd_dev, NULL);
  			if (rc < 0)
  				return rc;
  		}
@@ -3044,7 +3084,6 @@ static ssize_t rbd_add(struct bus_type *bus,
  	rc = rbd_dev_probe(rbd_dev);
  	if (rc < 0)
  		goto err_out_client;
-	rbd_assert(rbd_image_format_valid(rbd_dev->image_format));

  	/* no need to lock here, as rbd_dev is not registered yet */
  	rc = rbd_dev_snaps_update(rbd_dev);
-- 
1.7.9.5