Add the constants and structs necessary for later patches to start
implementing the NBD_OPT_EXTENDED_HEADERS extension in both the client
and server, matching recent upstream nbd.git (through commit
e6f3b94a934). This patch does not change any existing behavior, but
merely sets the stage for upcoming patches.
This patch does not change the status quo that neither the client nor
server use a packed-struct representation for the request header.
While most of the patch adds new types, there is also some churn for
renaming the existing NBDExtent to NBDExtent32 to contrast it with
NBDExtent64, which I thought was a nicer name than NBDExtentExt.
Signed-off-by: Eric Blake
---
v4: Hoist earlier in series, tweak a few comments, defer docs/interop
change to when feature is actually turned on, NBDExtent rename, add
QEMU_BUG_BUILD_ON for sanity sake, hoist in block status payload bits
from v3 14/14; R-b dropped
---
include/block/nbd.h | 124 +++-
nbd/nbd-internal.h | 3 +-
block/nbd.c | 6 +--
nbd/common.c| 12 -
nbd/server.c| 6 +--
5 files changed, 106 insertions(+), 45 deletions(-)
diff --git a/include/block/nbd.h b/include/block/nbd.h
index 52420660a65..f706e38dc72 100644
--- a/include/block/nbd.h
+++ b/include/block/nbd.h
@@ -59,7 +59,7 @@ typedef enum NBDMode {
NBD_MODE_EXPORT_NAME, /* newstyle but only OPT_EXPORT_NAME safe */
NBD_MODE_SIMPLE, /* newstyle but only simple replies */
NBD_MODE_STRUCTURED, /* newstyle, structured replies enabled */
-/* TODO add NBD_MODE_EXTENDED */
+NBD_MODE_EXTENDED, /* newstyle, extended headers enabled */
} NBDMode;
/* Transmission phase structs */
@@ -92,20 +92,36 @@ typedef struct NBDStructuredReplyChunk {
uint32_t length; /* length of payload */
} QEMU_PACKED NBDStructuredReplyChunk;
+typedef struct NBDExtendedReplyChunk {
+uint32_t magic; /* NBD_EXTENDED_REPLY_MAGIC */
+uint16_t flags; /* combination of NBD_REPLY_FLAG_* */
+uint16_t type; /* NBD_REPLY_TYPE_* */
+uint64_t cookie; /* request handle */
+uint64_t offset; /* request offset */
+uint64_t length; /* length of payload */
+} QEMU_PACKED NBDExtendedReplyChunk;
+
typedef union NBDReply {
NBDSimpleReply simple;
NBDStructuredReplyChunk structured;
+NBDExtendedReplyChunk extended;
struct {
/*
- * @magic and @cookie fields have the same offset and size both in
- * simple reply and structured reply chunk, so let them be accessible
- * without ".simple." or ".structured." specification
+ * @magic and @cookie fields have the same offset and size in all
+ * forms of replies, so let them be accessible without ".simple.",
+ * ".structured.", or ".extended." specifications.
*/
uint32_t magic;
uint32_t _skip;
uint64_t cookie;
-} QEMU_PACKED;
+};
} NBDReply;
+QEMU_BUILD_BUG_ON(offsetof(NBDReply, simple.cookie) !=
+ offsetof(NBDReply, cookie));
+QEMU_BUILD_BUG_ON(offsetof(NBDReply, structured.cookie) !=
+ offsetof(NBDReply, cookie));
+QEMU_BUILD_BUG_ON(offsetof(NBDReply, extended.cookie) !=
+ offsetof(NBDReply, cookie));
/* Header of chunk for NBD_REPLY_TYPE_OFFSET_DATA */
typedef struct NBDStructuredReadData {
@@ -132,14 +148,34 @@ typedef struct NBDStructuredError {
typedef struct NBDStructuredMeta {
/* header's length >= 12 (at least one extent) */
uint32_t context_id;
-/* extents follows */
+/* NBDExtent32 extents[] follows, array length implied by header */
} QEMU_PACKED NBDStructuredMeta;
-/* Extent chunk for NBD_REPLY_TYPE_BLOCK_STATUS */
-typedef struct NBDExtent {
+/* Extent array element for NBD_REPLY_TYPE_BLOCK_STATUS */
+typedef struct NBDExtent32 {
uint32_t length;
uint32_t flags; /* NBD_STATE_* */
-} QEMU_PACKED NBDExtent;
+} QEMU_PACKED NBDExtent32;
+
+/* Header of NBD_REPLY_TYPE_BLOCK_STATUS_EXT */
+typedef struct NBDExtendedMeta {
+/* header's length >= 24 (at least one extent) */
+uint32_t context_id;
+uint32_t count; /* header length must be count * 16 + 8 */
+/* NBDExtent64 extents[count] follows */
+} QEMU_PACKED NBDExtendedMeta;
+
+/* Extent array element for NBD_REPLY_TYPE_BLOCK_STATUS_EXT */
+typedef struct NBDExtent64 {
+uint64_t length;
+uint64_t flags; /* NBD_STATE_* */
+} QEMU_PACKED NBDExtent64;
+
+/* Client payload for limiting NBD_CMD_BLOCK_STATUS reply */
+typedef struct NBDBlockStatusPayload {
+uint64_t effect_length;
+/* uint32_t ids[] follows, array length implied by header */
+} QEMU_PACKED NBDBlockStatusPayload;
/* Transmission (export) flags: sent from server to client during handshake,
but describe what will happen during transmission */
@@ -157,20 +193,22 @@ enum {
NBD_FLAG_SEND_RESIZE_BIT= 9, /* Send resize */
NBD_FLAG_SEND_CACHE_BIT = 10, /* Send CACHE (prefetch) */
