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

[Josh Durgin <josh.durgin@inktank.com>]

Reviewed-by: Josh Durgin <josh.durgin@inktank.com>

On 10/09/2012 02:00 PM, Alex Elder wrote:
> 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);