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>

diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
index 3467693..de981ac 100644 (file)
--- 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;