rbd: get snapshot name for a v2 image

Define rbd_dev_v2_snap_name() to fetch the name for a particular
snapshot in a format 2 rbd image.

Define rbd_dev_v2_snap_info() to to be a wrapper for getting the
name, size, and features for a particular snapshot, using an
interface that matches the equivalent function for version 1 images.

Define rbd_dev_snap_info() wrapper function and use it to call the
appropriate function for getting the snapshot name, size, and
features, dependent on the rbd image format.

Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>

1 files changed, 79 insertions, 2 deletions

diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
index b673a8dc161d..b51f1c997c1d 100644
--- a/drivers/block/rbd.c
+++ b/drivers/block/rbd.c
@@ -2319,6 +2319,83 @@ out:
         return 0;
 }
 
+static char *rbd_dev_v2_snap_name(struct rbd_device *rbd_dev, u32 which)
+{
+        size_t size;
+        void *reply_buf;
+        __le64 snap_id;
+        int ret;
+        void *p;
+        void *end;
+        size_t snap_name_len;
+        char *snap_name;
+
+        size = sizeof (__le32) + RBD_MAX_SNAP_NAME_LEN;
+        reply_buf = kmalloc(size, GFP_KERNEL);
+        if (!reply_buf)
+                return ERR_PTR(-ENOMEM);
+
+        snap_id = cpu_to_le64(rbd_dev->header.snapc->snaps[which]);
+        ret = rbd_req_sync_exec(rbd_dev, rbd_dev->header_name,
+                                "rbd", "get_snapshot_name",
+                                (char *) &snap_id, sizeof (snap_id),
+                                reply_buf, size,
+                                CEPH_OSD_FLAG_READ, NULL);
+        dout("%s: rbd_req_sync_exec returned %d\n", __func__, ret);
+        if (ret < 0)
+                goto out;
+
+        p = reply_buf;
+        end = (char *) reply_buf + size;
+        snap_name_len = 0;
+        snap_name = ceph_extract_encoded_string(&p, end, &snap_name_len,
+                                GFP_KERNEL);
+        if (IS_ERR(snap_name)) {
+                ret = PTR_ERR(snap_name);
+                goto out;
+        } else {
+                dout("  snap_id 0x%016llx snap_name = %s\n",
+                        (unsigned long long) le64_to_cpu(snap_id), snap_name);
+        }
+        kfree(reply_buf);
+
+        return snap_name;
+out:
+        kfree(reply_buf);
+
+        return ERR_PTR(ret);
+}
+
+static char *rbd_dev_v2_snap_info(struct rbd_device *rbd_dev, u32 which,
+                u64 *snap_size, u64 *snap_features)
+{
+        __le64 snap_id;
+        u8 order;
+        int ret;
+
+        snap_id = rbd_dev->header.snapc->snaps[which];
+        ret = _rbd_dev_v2_snap_size(rbd_dev, snap_id, &order, snap_size);
+        if (ret)
+                return ERR_PTR(ret);
+        ret = _rbd_dev_v2_snap_features(rbd_dev, snap_id, snap_features);
+        if (ret)
+                return ERR_PTR(ret);
+
+        return rbd_dev_v2_snap_name(rbd_dev, which);
+}
+
+static char *rbd_dev_snap_info(struct rbd_device *rbd_dev, u32 which,
+                u64 *snap_size, u64 *snap_features)
+{
+        if (rbd_dev->image_format == 1)
+                return rbd_dev_v1_snap_info(rbd_dev, which,
+                                        snap_size, snap_features);
+        if (rbd_dev->image_format == 2)
+                return rbd_dev_v2_snap_info(rbd_dev, which,
+                                        snap_size, snap_features);
+        return ERR_PTR(-EINVAL);
+}
+
 /*
  * Scan the rbd device's current snapshot list and compare it to the
  * newly-received snapshot context.  Remove any existing snapshots
@@ -2372,8 +2449,8 @@ static int rbd_dev_snaps_update(struct rbd_device *rbd_dev)
                         continue;
                 }
 
-                snap_name = rbd_dev_v1_snap_info(rbd_dev, index,
-                                                &snap_size, &snap_features);
+                snap_name = rbd_dev_snap_info(rbd_dev, index,
+                                        &snap_size, &snap_features);
                 if (IS_ERR(snap_name))
                         return PTR_ERR(snap_name);