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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>
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@ -170,6 +170,7 @@ struct rbd_device {
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int major; /* blkdev assigned major */
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struct gendisk *disk; /* blkdev's gendisk and rq */
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u32 image_format; /* Either 1 or 2 */
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struct rbd_options rbd_opts;
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struct rbd_client *rbd_client;
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@ -507,6 +508,11 @@ static void rbd_coll_release(struct kref *kref)
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kfree(coll);
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}
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static bool rbd_image_format_valid(u32 image_format)
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{
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return image_format == 1 || image_format == 2;
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}
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static bool rbd_dev_ondisk_valid(struct rbd_image_header_ondisk *ondisk)
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{
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size_t size;
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@ -2584,6 +2590,96 @@ out:
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return ret;
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}
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static int rbd_dev_v1_probe(struct rbd_device *rbd_dev)
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{
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int ret;
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size_t size;
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/* Version 1 images have no id; empty string is used */
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rbd_dev->image_id = kstrdup("", GFP_KERNEL);
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if (!rbd_dev->image_id)
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return -ENOMEM;
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rbd_dev->image_id_len = 0;
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/* Record the header object name for this rbd image. */
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size = rbd_dev->image_name_len + sizeof (RBD_SUFFIX);
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rbd_dev->header_name = kmalloc(size, GFP_KERNEL);
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if (!rbd_dev->header_name) {
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ret = -ENOMEM;
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goto out_err;
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}
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sprintf(rbd_dev->header_name, "%s%s", rbd_dev->image_name, RBD_SUFFIX);
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/* Populate rbd image metadata */
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ret = rbd_read_header(rbd_dev, &rbd_dev->header);
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if (ret < 0)
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goto out_err;
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rbd_dev->image_format = 1;
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dout("discovered version 1 image, header name is %s\n",
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rbd_dev->header_name);
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return 0;
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out_err:
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kfree(rbd_dev->header_name);
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rbd_dev->header_name = NULL;
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kfree(rbd_dev->image_id);
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rbd_dev->image_id = NULL;
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return ret;
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}
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static int rbd_dev_v2_probe(struct rbd_device *rbd_dev)
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{
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size_t size;
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/*
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* Image id was filled in by the caller. Record the header
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* object name for this rbd image.
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*/
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size = sizeof (RBD_HEADER_PREFIX) + rbd_dev->image_id_len;
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rbd_dev->header_name = kmalloc(size, GFP_KERNEL);
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if (!rbd_dev->header_name)
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return -ENOMEM;
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sprintf(rbd_dev->header_name, "%s%s",
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RBD_HEADER_PREFIX, rbd_dev->image_id);
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rbd_dev->image_format = 2;
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dout("discovered version 2 image, header name is %s\n",
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rbd_dev->header_name);
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return -ENOTSUPP;
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}
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/*
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* Probe for the existence of the header object for the given rbd
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* device. For format 2 images this includes determining the image
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* id.
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*/
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static int rbd_dev_probe(struct rbd_device *rbd_dev)
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{
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int ret;
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/*
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* Get the id from the image id object. If it's not a
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* format 2 image, we'll get ENOENT back, and we'll assume
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* it's a format 1 image.
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*/
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ret = rbd_dev_image_id(rbd_dev);
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if (ret)
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ret = rbd_dev_v1_probe(rbd_dev);
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else
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ret = rbd_dev_v2_probe(rbd_dev);
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if (ret)
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dout("probe failed, returning %d\n", ret);
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return ret;
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}
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static ssize_t rbd_add(struct bus_type *bus,
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const char *buf,
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size_t count)
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@ -2631,35 +2727,10 @@ static ssize_t rbd_add(struct bus_type *bus,
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goto err_out_client;
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rbd_dev->pool_id = rc;
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rc = rbd_dev_image_id(rbd_dev);
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if (!rc) {
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rc = -ENOTSUPP; /* Not actually supporting format 2 yet */
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goto err_out_client;
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}
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/* Version 1 images have no id; empty string is used */
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rbd_dev->image_id = kstrdup("", GFP_KERNEL);
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if (!rbd_dev->image_id) {
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rc = -ENOMEM;
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goto err_out_client;
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}
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rbd_dev->image_id_len = 0;
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/* Create the name of the header object */
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rbd_dev->header_name = kmalloc(rbd_dev->image_name_len
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+ sizeof (RBD_SUFFIX),
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GFP_KERNEL);
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if (!rbd_dev->header_name)
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goto err_out_client;
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sprintf(rbd_dev->header_name, "%s%s", rbd_dev->image_name, RBD_SUFFIX);
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/* Get information about the image being mapped */
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rc = rbd_read_header(rbd_dev, &rbd_dev->header);
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if (rc)
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rc = rbd_dev_probe(rbd_dev);
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if (rc < 0)
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goto err_out_client;
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rbd_assert(rbd_image_format_valid(rbd_dev->image_format));
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/* no need to lock here, as rbd_dev is not registered yet */
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rc = rbd_dev_snaps_update(rbd_dev);
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