rbd: return obj version in __rbd_refresh_header()

Add a new parameter to __rbd_refresh_header() through which the
version of the header object is passed back to the caller.  In most
cases this isn't needed.  The main motivation is to normalize
(almost) all calls to __rbd_refresh_header() so they are all
wrapped immediately by mutex_lock()/mutex_unlock().

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

1 files changed, 11 insertions, 14 deletions

diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
index 34676937d2d2..de981ac72362 100644
--- a/drivers/block/rbd.c
+++ b/drivers/block/rbd.c
@@ -240,7 +240,7 @@ 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);
+static int __rbd_refresh_header(struct rbd_device *rbd_dev, u64 *hver);
 
 static int rbd_open(struct block_device *bdev, fmode_t mode)
 {
@@ -1226,8 +1226,7 @@ static void rbd_watch_cb(u64 ver, u64 notify_id, u8 opcode, void *data)
                 rbd_dev->header_name, (unsigned long long) notify_id,
                 (unsigned int) opcode);
         mutex_lock_nested(&ctl_mutex, SINGLE_DEPTH_NESTING);
-        rc = __rbd_refresh_header(rbd_dev);
-        hver = rbd_dev->header.obj_version;
+        rc = __rbd_refresh_header(rbd_dev, &hver);
         mutex_unlock(&ctl_mutex);
         if (rc)
                 pr_warning(RBD_DRV_NAME "%d got notification but failed to "
@@ -1707,7 +1706,7 @@ static void __rbd_remove_all_snaps(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)
+static int __rbd_refresh_header(struct rbd_device *rbd_dev, u64 *hver)
 {
         int ret;
         struct rbd_image_header h;
@@ -1732,6 +1731,8 @@ static int __rbd_refresh_header(struct rbd_device *rbd_dev)
         /* osd requests may still refer to snapc */
         ceph_put_snap_context(rbd_dev->header.snapc);
 
+        if (hver)
+                *hver = h.obj_version;
         rbd_dev->header.obj_version = h.obj_version;
         rbd_dev->header.image_size = h.image_size;
         rbd_dev->header.total_snaps = h.total_snaps;
@@ -1901,17 +1902,13 @@ static ssize_t rbd_image_refresh(struct device *dev,
                                  size_t size)
 {
         struct rbd_device *rbd_dev = dev_to_rbd_dev(dev);
-        int rc;
-        int ret = size;
+        int ret;
 
         mutex_lock_nested(&ctl_mutex, SINGLE_DEPTH_NESTING);
-
-        rc = __rbd_refresh_header(rbd_dev);
-        if (rc < 0)
-                ret = rc;
-
+        ret = __rbd_refresh_header(rbd_dev, NULL);
         mutex_unlock(&ctl_mutex);
-        return ret;
+
+        return ret < 0 ? ret : size;
 }
 
 static DEVICE_ATTR(size, S_IRUGO, rbd_size_show, NULL);
@@ -2200,7 +2197,7 @@ static int rbd_init_watch_dev(struct rbd_device *rbd_dev)
                 ret = rbd_req_sync_watch(rbd_dev);
                 if (ret == -ERANGE) {
                         mutex_lock_nested(&ctl_mutex, SINGLE_DEPTH_NESTING);
-                        rc = __rbd_refresh_header(rbd_dev);
+                        rc = __rbd_refresh_header(rbd_dev, NULL);
                         mutex_unlock(&ctl_mutex);
                         if (rc < 0)
                                 return rc;
@@ -2650,7 +2647,7 @@ static ssize_t rbd_snap_add(struct device *dev,
         if (ret < 0)
                 goto err_unlock;
 
-        ret = __rbd_refresh_header(rbd_dev);
+        ret = __rbd_refresh_header(rbd_dev, NULL);
         if (ret < 0)
                 goto err_unlock;