diff --git a/docs/interop/nbd.txt b/docs/interop/nbd.txt
index f3b3cacc96214b1ef7834b14771cbb83c415a872..10ce098a29bff89a805392831c90c7230ddb72cd 100644
--- a/docs/interop/nbd.txt
+++ b/docs/interop/nbd.txt
@@ -17,19 +17,31 @@ namespace "qemu".
== "qemu" namespace ==
-The "qemu" namespace currently contains only one type of context,
-related to exposing the contents of a dirty bitmap alongside the
-associated disk contents. That context has the following form:
+The "qemu" namespace currently contains two available metadata context
+types. The first is related to exposing the contents of a dirty
+bitmap alongside the associated disk contents. That metadata context
+is named with the following form:
qemu:dirty-bitmap:<dirty-bitmap-export-name>
Each dirty-bitmap metadata context defines only one flag for extents
in reply for NBD_CMD_BLOCK_STATUS:
- bit 0: NBD_STATE_DIRTY, means that the extent is "dirty"
+ bit 0: NBD_STATE_DIRTY, set when the extent is "dirty"
+
+The second is related to exposing the source of various extents within
+the image, with a single metadata context named:
+
+ qemu:allocation-depth
+
+In the allocation depth context, the entire 32-bit value represents a
+depth of which layer in a thin-provisioned backing chain provided the
+data (0 for unallocated, 1 for the active layer, 2 for the first
+backing layer, and so forth).
For NBD_OPT_LIST_META_CONTEXT the following queries are supported
-in addition to "qemu:dirty-bitmap:<dirty-bitmap-export-name>":
+in addition to the specific "qemu:allocation-depth" and
+"qemu:dirty-bitmap:<dirty-bitmap-export-name>":
* "qemu:" - returns list of all available metadata contexts in the
namespace.
@@ -55,3 +67,4 @@ the operation of that feature.
NBD_CMD_BLOCK_STATUS for "qemu:dirty-bitmap:", NBD_CMD_CACHE
* 4.2: NBD_FLAG_CAN_MULTI_CONN for shareable read-only exports,
NBD_CMD_FLAG_FAST_ZERO
+* 5.2: NBD_CMD_BLOCK_STATUS for "qemu:allocation-depth"
diff --git a/include/block/nbd.h b/include/block/nbd.h
index 3dd9a04546ec8531c475fe689f9eafa028897f79..4a52a43ef59882c8c31a06f1400212aa2722d155 100644
--- a/include/block/nbd.h
+++ b/include/block/nbd.h
@@ -1,5 +1,5 @@
/*
- * Copyright (C) 2016-2019 Red Hat, Inc.
+ * Copyright (C) 2016-2020 Red Hat, Inc.
* Copyright (C) 2005 Anthony Liguori <anthony@codemonkey.ws>
*
* Network Block Device
@@ -47,7 +47,7 @@ typedef struct NBDOptionReply NBDOptionReply;
typedef struct NBDOptionReplyMetaContext {
NBDOptionReply h; /* h.type = NBD_REP_META_CONTEXT, h.length > 4 */
uint32_t context_id;
- /* meta context name follows */
+ /* metadata context name follows */
} QEMU_PACKED NBDOptionReplyMetaContext;
/* Transmission phase structs
@@ -229,7 +229,7 @@ enum {
#define NBD_MAX_BUFFER_SIZE (32 * 1024 * 1024)
/*
- * Maximum size of a protocol string (export name, meta context name,
+ * Maximum size of a protocol string (export name, metadata context name,
* etc.). Use malloc rather than stack allocation for storage of a
* string.
*/
@@ -259,6 +259,8 @@ enum {
/* Extent flags for qemu:dirty-bitmap in NBD_REPLY_TYPE_BLOCK_STATUS */
#define NBD_STATE_DIRTY (1 << 0)
+/* No flags needed for qemu:allocation-depth in NBD_REPLY_TYPE_BLOCK_STATUS */
+
static inline bool nbd_reply_type_is_error(int type)
{
return type & (1 << 15);
diff --git a/nbd/server.c b/nbd/server.c
index b6841e455414acbcab670d4788009d53a3917674..ebbefcb6d3ec7780d8997cc584f1832dc9c3238a 100644
--- a/nbd/server.c
+++ b/nbd/server.c
@@ -27,8 +27,9 @@
#include "qemu/units.h"
#define NBD_META_ID_BASE_ALLOCATION 0
+#define NBD_META_ID_ALLOCATION_DEPTH 1
/* Dirty bitmaps use 'NBD_META_ID_DIRTY_BITMAP + i', so keep this id last. */
-#define NBD_META_ID_DIRTY_BITMAP 1
+#define NBD_META_ID_DIRTY_BITMAP 2
/*
* NBD_MAX_BLOCK_STATUS_EXTENTS: 1 MiB of extents data. An empirical
@@ -95,6 +96,7 @@ struct NBDExport {
BlockBackend *eject_notifier_blk;
Notifier eject_notifier;
+ bool allocation_depth;
BdrvDirtyBitmap **export_bitmaps;
size_t nr_export_bitmaps;
};
@@ -108,6 +110,7 @@ typedef struct NBDExportMetaContexts {
NBDExport *exp;
size_t count; /* number of negotiated contexts */
bool base_allocation; /* export base:allocation context (block status) */
+ bool allocation_depth; /* export qemu:allocation-depth */
bool *bitmaps; /*
* export qemu:dirty-bitmap:<export bitmap name>,
* sized by exp->nr_export_bitmaps
@@ -857,7 +860,8 @@ static bool nbd_meta_base_query(NBDClient *client, NBDExportMetaContexts *meta,
/* nbd_meta_qemu_query
*
* Handle queries to 'qemu' namespace. For now, only the qemu:dirty-bitmap:
- * context is available. Return true if @query has been handled.
+ * and qemu:allocation-depth contexts are available. Return true if @query
+ * has been handled.
*/
static bool nbd_meta_qemu_query(NBDClient *client, NBDExportMetaContexts *meta,
const char *query)
@@ -871,12 +875,19 @@ static bool nbd_meta_qemu_query(NBDClient *client, NBDExportMetaContexts *meta,
if (!*query) {
if (client->opt == NBD_OPT_LIST_META_CONTEXT) {
+ meta->allocation_depth = meta->exp->allocation_depth;
memset(meta->bitmaps, 1, meta->exp->nr_export_bitmaps);
}
trace_nbd_negotiate_meta_query_parse("empty");
return true;
}
+ if (strcmp(query, "allocation-depth") == 0) {
+ trace_nbd_negotiate_meta_query_parse("allocation-depth");
+ meta->allocation_depth = meta->exp->allocation_depth;
+ return true;
+ }
+
if (nbd_strshift(&query, "dirty-bitmap:")) {
trace_nbd_negotiate_meta_query_parse("dirty-bitmap:");
if (!*query) {
@@ -901,7 +912,7 @@ static bool nbd_meta_qemu_query(NBDClient *client, NBDExportMetaContexts *meta,
return true;
}
- trace_nbd_negotiate_meta_query_skip("not dirty-bitmap");
+ trace_nbd_negotiate_meta_query_skip("unknown qemu context");
return true;
}
@@ -1008,6 +1019,7 @@ static int nbd_negotiate_meta_queries(NBDClient *client,
if (client->opt == NBD_OPT_LIST_META_CONTEXT && !nb_queries) {
/* enable all known contexts */
meta->base_allocation = true;
+ meta->allocation_depth = meta->exp->allocation_depth;
memset(meta->bitmaps, 1, meta->exp->nr_export_bitmaps);
} else {
for (i = 0; i < nb_queries; ++i) {
@@ -1028,6 +1040,16 @@ static int nbd_negotiate_meta_queries(NBDClient *client,
count++;
}
+ if (meta->allocation_depth) {
+ ret = nbd_negotiate_send_meta_context(client, "qemu:allocation-depth",
+ NBD_META_ID_ALLOCATION_DEPTH,
+ errp);
+ if (ret < 0) {
+ return ret;
+ }
+ count++;
+ }
+
for (i = 0; i < meta->exp->nr_export_bitmaps; i++) {
const char *bm_name;
g_autofree char *context = NULL;
@@ -2005,6 +2027,29 @@ static int blockstatus_to_extents(BlockDriverState *bs, uint64_t offset,
return 0;
}
+static int blockalloc_to_extents(BlockDriverState *bs, uint64_t offset,
+ uint64_t bytes, NBDExtentArray *ea)
+{
+ while (bytes) {
+ int64_t num;
+ int ret = bdrv_is_allocated_above(bs, NULL, false, offset, bytes,
+ &num);
+
+ if (ret < 0) {
+ return ret;
+ }
+
+ if (nbd_extent_array_add(ea, num, ret) < 0) {
+ return 0;
+ }
+
+ offset += num;
+ bytes -= num;
+ }
+
+ return 0;
+}
+
/*
* nbd_co_send_extents
*
@@ -2044,7 +2089,11 @@ static int nbd_co_send_block_status(NBDClient *client, uint64_t handle,
unsigned int nb_extents = dont_fragment ? 1 : NBD_MAX_BLOCK_STATUS_EXTENTS;
g_autoptr(NBDExtentArray) ea = nbd_extent_array_new(nb_extents);
- ret = blockstatus_to_extents(bs, offset, length, ea);
+ if (context_id == NBD_META_ID_BASE_ALLOCATION) {
+ ret = blockstatus_to_extents(bs, offset, length, ea);
+ } else {
+ ret = blockalloc_to_extents(bs, offset, length, ea);
+ }
if (ret < 0) {
return nbd_co_send_structured_error(
client, handle, -ret, "can't get block status", errp);
@@ -2395,6 +2444,19 @@ static coroutine_fn int nbd_handle_request(NBDClient *client,
}
}
+ if (client->export_meta.allocation_depth) {
+ ret = nbd_co_send_block_status(client, request->handle,
+ blk_bs(exp->common.blk),
+ request->from, request->len,
+ dont_fragment,
+ !--contexts_remaining,
+ NBD_META_ID_ALLOCATION_DEPTH,
+ errp);
+ if (ret < 0) {
+ return ret;
+ }
+ }
+
for (i = 0; i < client->exp->nr_export_bitmaps; i++) {
if (!client->export_meta.bitmaps[i]) {
continue;