rbd: lay out header probe infrastructure
This defines a new function rbd_dev_probe() as a top-level
function for populating detailed information about an rbd device.
It first checks for the existence of a format 2 rbd image id object.
If it exists, the image is assumed to be a format 2 rbd image, and
another function rbd_dev_v2() is called to finish populating
header data for that image. If it does not exist, it is assumed to
be an old (format 1) rbd image, and calls a similar function
rbd_dev_v1() to populate its header information.
A new field, rbd_dev->format, is defined to record which version
of the rbd image format the device represents. For a valid mapped
rbd device it will have one of two values, 1 or 2.
So far, the format 2 images are not really supported; this is
laying out the infrastructure for fleshing out that support.
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 366a3a1..3b284d5 100644
--- a/drivers/block/rbd.c
+++ b/drivers/block/rbd.c
@@ -170,6 +170,7 @@
int major; /* blkdev assigned major */
struct gendisk *disk; /* blkdev's gendisk and rq */
+ u32 image_format; /* Either 1 or 2 */
struct rbd_options rbd_opts;
struct rbd_client *rbd_client;
@@ -507,6 +508,11 @@
kfree(coll);
}
+static bool rbd_image_format_valid(u32 image_format)
+{
+ return image_format == 1 || image_format == 2;
+}
+
static bool rbd_dev_ondisk_valid(struct rbd_image_header_ondisk *ondisk)
{
size_t size;
@@ -2584,6 +2590,96 @@
return ret;
}
+static int rbd_dev_v1_probe(struct rbd_device *rbd_dev)
+{
+ int ret;
+ size_t size;
+
+ /* Version 1 images have no id; empty string is used */
+
+ rbd_dev->image_id = kstrdup("", GFP_KERNEL);
+ if (!rbd_dev->image_id)
+ return -ENOMEM;
+ rbd_dev->image_id_len = 0;
+
+ /* Record the header object name for this rbd image. */
+
+ size = rbd_dev->image_name_len + sizeof (RBD_SUFFIX);
+ rbd_dev->header_name = kmalloc(size, GFP_KERNEL);
+ if (!rbd_dev->header_name) {
+ ret = -ENOMEM;
+ goto out_err;
+ }
+ sprintf(rbd_dev->header_name, "%s%s", rbd_dev->image_name, RBD_SUFFIX);
+
+ /* Populate rbd image metadata */
+
+ ret = rbd_read_header(rbd_dev, &rbd_dev->header);
+ if (ret < 0)
+ goto out_err;
+ rbd_dev->image_format = 1;
+
+ dout("discovered version 1 image, header name is %s\n",
+ rbd_dev->header_name);
+
+ return 0;
+
+out_err:
+ kfree(rbd_dev->header_name);
+ rbd_dev->header_name = NULL;
+ kfree(rbd_dev->image_id);
+ rbd_dev->image_id = NULL;
+
+ return ret;
+}
+
+static int rbd_dev_v2_probe(struct rbd_device *rbd_dev)
+{
+ size_t size;
+
+ /*
+ * Image id was filled in by the caller. Record the header
+ * object name for this rbd image.
+ */
+ size = sizeof (RBD_HEADER_PREFIX) + rbd_dev->image_id_len;
+ rbd_dev->header_name = kmalloc(size, GFP_KERNEL);
+ if (!rbd_dev->header_name)
+ return -ENOMEM;
+ sprintf(rbd_dev->header_name, "%s%s",
+ RBD_HEADER_PREFIX, rbd_dev->image_id);
+ rbd_dev->image_format = 2;
+
+ dout("discovered version 2 image, header name is %s\n",
+ rbd_dev->header_name);
+
+ return -ENOTSUPP;
+}
+
+/*
+ * Probe for the existence of the header object for the given rbd
+ * device. For format 2 images this includes determining the image
+ * id.
+ */
+static int rbd_dev_probe(struct rbd_device *rbd_dev)
+{
+ int ret;
+
+ /*
+ * Get the id from the image id object. If it's not a
+ * format 2 image, we'll get ENOENT back, and we'll assume
+ * it's a format 1 image.
+ */
+ ret = rbd_dev_image_id(rbd_dev);
+ if (ret)
+ ret = rbd_dev_v1_probe(rbd_dev);
+ else
+ ret = rbd_dev_v2_probe(rbd_dev);
+ if (ret)
+ dout("probe failed, returning %d\n", ret);
+
+ return ret;
+}
+
static ssize_t rbd_add(struct bus_type *bus,
const char *buf,
size_t count)
@@ -2631,35 +2727,10 @@
goto err_out_client;
rbd_dev->pool_id = rc;
- rc = rbd_dev_image_id(rbd_dev);
- if (!rc) {
- rc = -ENOTSUPP; /* Not actually supporting format 2 yet */
+ rc = rbd_dev_probe(rbd_dev);
+ if (rc < 0)
goto err_out_client;
- }
-
- /* Version 1 images have no id; empty string is used */
-
- rbd_dev->image_id = kstrdup("", GFP_KERNEL);
- if (!rbd_dev->image_id) {
- rc = -ENOMEM;
- goto err_out_client;
- }
- rbd_dev->image_id_len = 0;
-
- /* Create the name of the header object */
-
- rbd_dev->header_name = kmalloc(rbd_dev->image_name_len
- + sizeof (RBD_SUFFIX),
- GFP_KERNEL);
- if (!rbd_dev->header_name)
- goto err_out_client;
- sprintf(rbd_dev->header_name, "%s%s", rbd_dev->image_name, RBD_SUFFIX);
-
- /* Get information about the image being mapped */
-
- rc = rbd_read_header(rbd_dev, &rbd_dev->header);
- if (rc)
- 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);