rbd: factor out get_parent_info()

In preparation for the new parent_get and parent_overlap_get class
methods, factor out the fetching and decoding of parent data.

As a side effect, we now decode all four fields in the "no parent"
case.

Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Reviewed-by: Jason Dillaman <dillaman@redhat.com>

diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
index 7915f3b..bec5a50 100644 (file)
--- a/drivers/block/rbd.c
+++ b/drivers/block/rbd.c
@@ -4584,47 +4584,95 @@ static int rbd_dev_v2_features(struct rbd_device *rbd_dev)
                                                &rbd_dev->header.features);
 }
 
+struct parent_image_info {
+       u64             pool_id;
+       const char      *image_id;
+       u64             snap_id;
+
+       u64             overlap;
+};
+
+/*
+ * The caller is responsible for @pii.
+ */
+static int __get_parent_info_legacy(struct rbd_device *rbd_dev,
+                                   struct page *req_page,
+                                   struct page *reply_page,
+                                   struct parent_image_info *pii)
+{
+       struct ceph_osd_client *osdc = &rbd_dev->rbd_client->client->osdc;
+       size_t reply_len = PAGE_SIZE;
+       void *p, *end;
+       int ret;
+
+       ret = ceph_osdc_call(osdc, &rbd_dev->header_oid, &rbd_dev->header_oloc,
+                            "rbd", "get_parent", CEPH_OSD_FLAG_READ,
+                            req_page, sizeof(u64), reply_page, &reply_len);
+       if (ret)
+               return ret;
+
+       p = page_address(reply_page);
+       end = p + reply_len;
+       ceph_decode_64_safe(&p, end, pii->pool_id, e_inval);
+       pii->image_id = ceph_extract_encoded_string(&p, end, NULL, GFP_KERNEL);
+       if (IS_ERR(pii->image_id)) {
+               ret = PTR_ERR(pii->image_id);
+               pii->image_id = NULL;
+               return ret;
+       }
+       ceph_decode_64_safe(&p, end, pii->snap_id, e_inval);
+       ceph_decode_64_safe(&p, end, pii->overlap, e_inval);
+
+       return 0;
+
+e_inval:
+       return -EINVAL;
+}
+
+static int get_parent_info(struct rbd_device *rbd_dev,
+                          struct parent_image_info *pii)
+{
+       struct page *req_page, *reply_page;
+       void *p;
+       int ret;
+
+       req_page = alloc_page(GFP_KERNEL);
+       if (!req_page)
+               return -ENOMEM;
+
+       reply_page = alloc_page(GFP_KERNEL);
+       if (!reply_page) {
+               __free_page(req_page);
+               return -ENOMEM;
+       }
+
+       p = page_address(req_page);
+       ceph_encode_64(&p, rbd_dev->spec->snap_id);
+       ret = __get_parent_info_legacy(rbd_dev, req_page, reply_page, pii);
+
+       __free_page(req_page);
+       __free_page(reply_page);
+       return ret;
+}
+
 static int rbd_dev_v2_parent_info(struct rbd_device *rbd_dev)
 {
        struct rbd_spec *parent_spec;
-       size_t size;
-       void *reply_buf = NULL;
-       __le64 snapid;
-       void *p;
-       void *end;
-       u64 pool_id;
-       char *image_id;
-       u64 snap_id;
-       u64 overlap;
+       struct parent_image_info pii = { 0 };
        int ret;
 
        parent_spec = rbd_spec_alloc();
        if (!parent_spec)
                return -ENOMEM;
 
-       size = sizeof (__le64) +                                /* pool_id */
-               sizeof (__le32) + RBD_IMAGE_ID_LEN_MAX +        /* image_id */
-               sizeof (__le64) +                               /* snap_id */
-               sizeof (__le64);                                /* overlap */
-       reply_buf = kmalloc(size, GFP_KERNEL);
-       if (!reply_buf) {
-               ret = -ENOMEM;
+       ret = get_parent_info(rbd_dev, &pii);
+       if (ret)
                goto out_err;
-       }
 
-       snapid = cpu_to_le64(rbd_dev->spec->snap_id);
-       ret = rbd_obj_method_sync(rbd_dev, &rbd_dev->header_oid,
-                                 &rbd_dev->header_oloc, "get_parent",
-                                 &snapid, sizeof(snapid), reply_buf, size);
-       dout("%s: rbd_obj_method_sync returned %d\n", __func__, ret);
-       if (ret < 0)
-               goto out_err;
+       dout("%s pool_id %llu image_id %s snap_id %llu overlap %llu\n",
+            __func__, pii.pool_id, pii.image_id, pii.snap_id, pii.overlap);
 
-       p = reply_buf;
-       end = reply_buf + ret;
-       ret = -ERANGE;
-       ceph_decode_64_safe(&p, end, pool_id, out_err);
-       if (pool_id == CEPH_NOPOOL) {
+       if (pii.pool_id == CEPH_NOPOOL) {
                /*
                 * Either the parent never existed, or we have
                 * record of it but the image got flattened so it no
@@ -4647,19 +4695,11 @@ static int rbd_dev_v2_parent_info(struct rbd_device *rbd_dev)
        /* The ceph file layout needs to fit pool id in 32 bits */
 
        ret = -EIO;
-       if (pool_id > (u64)U32_MAX) {
+       if (pii.pool_id > (u64)U32_MAX) {
                rbd_warn(NULL, "parent pool id too large (%llu > %u)",
-                       (unsigned long long)pool_id, U32_MAX);
-               goto out_err;
-       }
-
-       image_id = ceph_extract_encoded_string(&p, end, NULL, GFP_KERNEL);
-       if (IS_ERR(image_id)) {
-               ret = PTR_ERR(image_id);
+                       (unsigned long long)pii.pool_id, U32_MAX);
                goto out_err;
        }
-       ceph_decode_64_safe(&p, end, snap_id, out_err);
-       ceph_decode_64_safe(&p, end, overlap, out_err);
 
        /*
         * The parent won't change (except when the clone is
@@ -4667,9 +4707,10 @@ static int rbd_dev_v2_parent_info(struct rbd_device *rbd_dev)
         * record the parent spec we have not already done so.
         */
        if (!rbd_dev->parent_spec) {
-               parent_spec->pool_id = pool_id;
-               parent_spec->image_id = image_id;
-               parent_spec->snap_id = snap_id;
+               parent_spec->pool_id = pii.pool_id;
+               parent_spec->image_id = pii.image_id;
+               pii.image_id = NULL;
+               parent_spec->snap_id = pii.snap_id;
 
                /* TODO: support cloning across namespaces */
                if (rbd_dev->spec->pool_ns) {
@@ -4683,15 +4724,13 @@ static int rbd_dev_v2_parent_info(struct rbd_device *rbd_dev)
 
                rbd_dev->parent_spec = parent_spec;
                parent_spec = NULL;     /* rbd_dev now owns this */
-       } else {
-               kfree(image_id);
        }
 
        /*
         * We always update the parent overlap.  If it's zero we issue
         * a warning, as we will proceed as if there was no parent.
         */
-       if (!overlap) {
+       if (!pii.overlap) {
                if (parent_spec) {
                        /* refresh, careful to warn just once */
                        if (rbd_dev->parent_overlap)
@@ -4702,14 +4741,13 @@ static int rbd_dev_v2_parent_info(struct rbd_device *rbd_dev)
                        rbd_warn(rbd_dev, "clone is standalone (overlap 0)");
                }
        }
-       rbd_dev->parent_overlap = overlap;
+       rbd_dev->parent_overlap = pii.overlap;
 
 out:
        ret = 0;
 out_err:
-       kfree(reply_buf);
+       kfree(pii.image_id);
        rbd_spec_put(parent_spec);
-
        return ret;
 }