rbd: add 'config_info' sysfs rbd device attribute

Export the info used to setup the rbd image, so it can be used to remap
the image.

Signed-off-by: Mike Christie <mchristi@redhat.com>
[idryomov@gmail.com: do_rbd_add() EH]
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>

diff --git a/Documentation/ABI/testing/sysfs-bus-rbd b/Documentation/ABI/testing/sysfs-bus-rbd
index 7bf8d4f..6dccbf8 100644 (file)
--- a/Documentation/ABI/testing/sysfs-bus-rbd
+++ b/Documentation/ABI/testing/sysfs-bus-rbd
@@ -57,6 +57,11 @@ cluster_fsid
 
        The ceph cluster UUID.  (August 2016, since 4.9.)
 
+config_info
+
+       The string written into /sys/bus/rbd/add{,_single_major}.  (August
+       2016, since 4.9.)
+
 features
 
        A hexadecimal encoding of the feature bits for this image.

diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
index 36ebec1..8ff2dc8 100644 (file)
--- a/drivers/block/rbd.c
+++ b/drivers/block/rbd.c
@@ -370,6 +370,7 @@ struct rbd_device {
        unsigned long           flags;          /* possibly lock protected */
        struct rbd_spec         *spec;
        struct rbd_options      *opts;
+       char                    *config_info;   /* add{,_single_major} string */
 
        struct ceph_object_id   header_oid;
        struct ceph_object_locator header_oloc;
@@ -4620,6 +4621,14 @@ static ssize_t rbd_cluster_fsid_show(struct device *dev,
        return sprintf(buf, "%pU\n", &rbd_dev->rbd_client->client->fsid);
 }
 
+static ssize_t rbd_config_info_show(struct device *dev,
+                                   struct device_attribute *attr, char *buf)
+{
+       struct rbd_device *rbd_dev = dev_to_rbd_dev(dev);
+
+       return sprintf(buf, "%s\n", rbd_dev->config_info);
+}
+
 static ssize_t rbd_pool_show(struct device *dev,
                             struct device_attribute *attr, char *buf)
 {
@@ -4732,6 +4741,7 @@ static DEVICE_ATTR(minor, S_IRUGO, rbd_minor_show, NULL);
 static DEVICE_ATTR(client_addr, S_IRUGO, rbd_client_addr_show, NULL);
 static DEVICE_ATTR(client_id, S_IRUGO, rbd_client_id_show, NULL);
 static DEVICE_ATTR(cluster_fsid, S_IRUGO, rbd_cluster_fsid_show, NULL);
+static DEVICE_ATTR(config_info, S_IRUSR, rbd_config_info_show, NULL);
 static DEVICE_ATTR(pool, S_IRUGO, rbd_pool_show, NULL);
 static DEVICE_ATTR(pool_id, S_IRUGO, rbd_pool_id_show, NULL);
 static DEVICE_ATTR(name, S_IRUGO, rbd_name_show, NULL);
@@ -4749,6 +4759,7 @@ static struct attribute *rbd_attrs[] = {
        &dev_attr_client_addr.attr,
        &dev_attr_client_id.attr,
        &dev_attr_cluster_fsid.attr,
+       &dev_attr_config_info.attr,
        &dev_attr_pool.attr,
        &dev_attr_pool_id.attr,
        &dev_attr_name.attr,
@@ -4824,6 +4835,7 @@ static void rbd_dev_free(struct rbd_device *rbd_dev)
 
        ceph_oid_destroy(&rbd_dev->header_oid);
        ceph_oloc_destroy(&rbd_dev->header_oloc);
+       kfree(rbd_dev->config_info);
 
        rbd_put_client(rbd_dev->rbd_client);
        rbd_spec_put(rbd_dev->spec);
@@ -6223,10 +6235,18 @@ static ssize_t do_rbd_add(struct bus_type *bus,
        spec = NULL;            /* rbd_dev now owns this */
        rbd_opts = NULL;        /* rbd_dev now owns this */
 
+       rbd_dev->config_info = kstrdup(buf, GFP_KERNEL);
+       if (!rbd_dev->config_info) {
+               rc = -ENOMEM;
+               goto err_out_rbd_dev;
+       }
+
        down_write(&rbd_dev->header_rwsem);
        rc = rbd_dev_image_probe(rbd_dev, 0);
-       if (rc < 0)
+       if (rc < 0) {
+               up_write(&rbd_dev->header_rwsem);
                goto err_out_rbd_dev;
+       }
 
        /* If we are mapping a snapshot it must be marked read-only */
 
@@ -6253,7 +6273,6 @@ out:
        return rc;
 
 err_out_rbd_dev:
-       up_write(&rbd_dev->header_rwsem);
        rbd_dev_destroy(rbd_dev);
 err_out_client:
        rbd_put_client(rbdc);