rbd: get parent spec for version 2 images
Add support for getting the the information identifying the parent image for rbd images that have them. The child image holds a reference to its parent image specification structure. Create a new entry "parent" in /sys/bus/rbd/image/N/ to report the identifying information for the parent image, if any. Signed-off-by: Alex Elder <elder@inktank.com> Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
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Alex Elder
parent
a92ffdf8a9
commit
86b00e0da6
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@ -70,6 +70,10 @@ snap_*
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A directory per each snapshot
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parent
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Information identifying the pool, image, and snapshot id for
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the parent image in a layered rbd image (format 2 only).
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Entries under /sys/bus/rbd/devices/<dev-id>/snap_<snap-name>
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-------------------------------------------------------------
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@ -217,6 +217,9 @@ struct rbd_device {
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struct ceph_osd_event *watch_event;
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struct ceph_osd_request *watch_request;
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struct rbd_spec *parent_spec;
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u64 parent_overlap;
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/* protects updating the header */
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struct rw_semaphore header_rwsem;
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@ -2009,6 +2012,49 @@ static ssize_t rbd_snap_show(struct device *dev,
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return sprintf(buf, "%s\n", rbd_dev->spec->snap_name);
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}
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/*
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* For an rbd v2 image, shows the pool id, image id, and snapshot id
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* for the parent image. If there is no parent, simply shows
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* "(no parent image)".
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*/
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static ssize_t rbd_parent_show(struct device *dev,
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struct device_attribute *attr,
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char *buf)
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{
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struct rbd_device *rbd_dev = dev_to_rbd_dev(dev);
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struct rbd_spec *spec = rbd_dev->parent_spec;
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int count;
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char *bufp = buf;
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if (!spec)
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return sprintf(buf, "(no parent image)\n");
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count = sprintf(bufp, "pool_id %llu\npool_name %s\n",
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(unsigned long long) spec->pool_id, spec->pool_name);
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if (count < 0)
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return count;
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bufp += count;
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count = sprintf(bufp, "image_id %s\nimage_name %s\n", spec->image_id,
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spec->image_name ? spec->image_name : "(unknown)");
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if (count < 0)
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return count;
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bufp += count;
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count = sprintf(bufp, "snap_id %llu\nsnap_name %s\n",
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(unsigned long long) spec->snap_id, spec->snap_name);
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if (count < 0)
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return count;
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bufp += count;
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count = sprintf(bufp, "overlap %llu\n", rbd_dev->parent_overlap);
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if (count < 0)
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return count;
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bufp += count;
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return (ssize_t) (bufp - buf);
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}
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static ssize_t rbd_image_refresh(struct device *dev,
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struct device_attribute *attr,
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const char *buf,
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@ -2032,6 +2078,7 @@ static DEVICE_ATTR(name, S_IRUGO, rbd_name_show, NULL);
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static DEVICE_ATTR(image_id, S_IRUGO, rbd_image_id_show, NULL);
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static DEVICE_ATTR(refresh, S_IWUSR, NULL, rbd_image_refresh);
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static DEVICE_ATTR(current_snap, S_IRUGO, rbd_snap_show, NULL);
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static DEVICE_ATTR(parent, S_IRUGO, rbd_parent_show, NULL);
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static struct attribute *rbd_attrs[] = {
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&dev_attr_size.attr,
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@ -2043,6 +2090,7 @@ static struct attribute *rbd_attrs[] = {
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&dev_attr_name.attr,
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&dev_attr_image_id.attr,
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&dev_attr_current_snap.attr,
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&dev_attr_parent.attr,
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&dev_attr_refresh.attr,
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NULL
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};
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@ -2192,6 +2240,7 @@ struct rbd_device *rbd_dev_create(struct rbd_client *rbdc,
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static void rbd_dev_destroy(struct rbd_device *rbd_dev)
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{
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rbd_spec_put(rbd_dev->parent_spec);
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kfree(rbd_dev->header_name);
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rbd_put_client(rbd_dev->rbd_client);
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rbd_spec_put(rbd_dev->spec);
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@ -2400,6 +2449,71 @@ static int rbd_dev_v2_features(struct rbd_device *rbd_dev)
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&rbd_dev->header.features);
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}
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static int rbd_dev_v2_parent_info(struct rbd_device *rbd_dev)
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{
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struct rbd_spec *parent_spec;
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size_t size;
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void *reply_buf = NULL;
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__le64 snapid;
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void *p;
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void *end;
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char *image_id;
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u64 overlap;
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size_t len = 0;
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int ret;
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parent_spec = rbd_spec_alloc();
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if (!parent_spec)
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return -ENOMEM;
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size = sizeof (__le64) + /* pool_id */
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sizeof (__le32) + RBD_IMAGE_ID_LEN_MAX + /* image_id */
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sizeof (__le64) + /* snap_id */
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sizeof (__le64); /* overlap */
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reply_buf = kmalloc(size, GFP_KERNEL);
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if (!reply_buf) {
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ret = -ENOMEM;
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goto out_err;
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}
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snapid = cpu_to_le64(CEPH_NOSNAP);
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ret = rbd_req_sync_exec(rbd_dev, rbd_dev->header_name,
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"rbd", "get_parent",
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(char *) &snapid, sizeof (snapid),
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(char *) reply_buf, size,
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CEPH_OSD_FLAG_READ, NULL);
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dout("%s: rbd_req_sync_exec returned %d\n", __func__, ret);
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if (ret < 0)
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goto out_err;
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ret = -ERANGE;
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p = reply_buf;
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end = (char *) reply_buf + size;
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ceph_decode_64_safe(&p, end, parent_spec->pool_id, out_err);
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if (parent_spec->pool_id == CEPH_NOPOOL)
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goto out; /* No parent? No problem. */
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image_id = ceph_extract_encoded_string(&p, end, &len, GFP_KERNEL);
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if (IS_ERR(image_id)) {
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ret = PTR_ERR(image_id);
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goto out_err;
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}
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parent_spec->image_id = image_id;
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ceph_decode_64_safe(&p, end, parent_spec->snap_id, out_err);
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ceph_decode_64_safe(&p, end, overlap, out_err);
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rbd_dev->parent_overlap = overlap;
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rbd_dev->parent_spec = parent_spec;
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parent_spec = NULL; /* rbd_dev now owns this */
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out:
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ret = 0;
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out_err:
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kfree(reply_buf);
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rbd_spec_put(parent_spec);
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return ret;
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}
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static int rbd_dev_v2_snap_context(struct rbd_device *rbd_dev, u64 *ver)
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{
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size_t size;
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@ -3154,6 +3268,12 @@ static int rbd_dev_v1_probe(struct rbd_device *rbd_dev)
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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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/* Version 1 images have no parent (no layering) */
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rbd_dev->parent_spec = NULL;
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rbd_dev->parent_overlap = 0;
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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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@ -3205,6 +3325,14 @@ static int rbd_dev_v2_probe(struct rbd_device *rbd_dev)
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if (ret < 0)
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goto out_err;
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/* If the image supports layering, get the parent info */
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if (rbd_dev->header.features & RBD_FEATURE_LAYERING) {
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ret = rbd_dev_v2_parent_info(rbd_dev);
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if (ret < 0)
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goto out_err;
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}
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/* crypto and compression type aren't (yet) supported for v2 images */
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rbd_dev->header.crypt_type = 0;
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@ -3224,6 +3352,9 @@ static int rbd_dev_v2_probe(struct rbd_device *rbd_dev)
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return 0;
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out_err:
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rbd_dev->parent_overlap = 0;
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rbd_spec_put(rbd_dev->parent_spec);
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rbd_dev->parent_spec = NULL;
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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->header.object_prefix);
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@ -87,6 +87,8 @@ struct ceph_pg {
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*
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* lpgp_num -- as above.
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*/
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#define CEPH_NOPOOL ((__u64) (-1)) /* pool id not defined */
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#define CEPH_PG_TYPE_REP 1
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#define CEPH_PG_TYPE_RAID4 2
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#define CEPH_PG_POOL_VERSION 2
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