[Libguestfs] [libnbd PATCH v3 07/22] generator: Add struct nbd_extent in prep for 64-bit extents
Eric Blake
eblake at redhat.com
Thu May 25 13:00:53 UTC 2023
The existing nbd_block_status() callback is permanently stuck with an
array of uint32_t pairs (len/2 extents), which is both constrained on
maximum extent size (no larger than 4G) and on the status flags (must
fit in 32 bits). While the "base:allocation" metacontext will never
exceed 32 bits, it is not hard to envision other extension
metacontexts where a 64-bit status would be useful (for example, Zoned
Block Devices expressing a 64-bit offset[1]). Exposing 64-bit extents
will require a new API; we now have the decision of whether to copy
the existing API practice of returning a bare array containing len/2
extent pairs, or with a saner idea of an array of structs with len
extents. Returning an array of structs is actually easier to map to
various language bindings, particularly since we know the length field
will generally fit in 63-bits (fallout from the fact that NBD exports
are effectively capped in size by signed off_t), but where the status
field must represent a full 64 bits (assuming that the user wants to
connect to a metadata extension that utilizes 64 bits, rather than
existing metadata contexts that only expose 32 bits).
This patch introduces the struct we plan to use in the new API, along
with language bindings. The bindings for Python and OCaml were
relatively straightforward; the Golang bindings took a bit more effort
for me to write. Temporary unused attributes are needed to keep the
compiler happy until a later patch exposes a new API using the new
callback type.
Note that 'struct nbd_block_descriptor_ext' in lib/nbd-protocol.h is
exactly the same as what we want to use in C. But it is easier to
stick a new public type in <libnbd.h> than to figure out how to expose
just part of a header we only want to use internally.
[1] https://zonedstorage.io/docs/linux/zbd-api
Signed-off-by: Eric Blake <eblake at redhat.com>
---
generator/API.mli | 1 +
generator/API.ml | 12 +++++++++++-
generator/C.ml | 24 +++++++++++++++++++++---
generator/GoLang.ml | 24 ++++++++++++++++++++++++
generator/OCaml.ml | 24 +++++++++++++++++++++---
generator/Python.ml | 21 ++++++++++++++++++++-
ocaml/helpers.c | 20 ++++++++++++++++++++
ocaml/nbd-c.h | 1 +
golang/handle.go | 6 ++++++
9 files changed, 125 insertions(+), 8 deletions(-)
diff --git a/generator/API.mli b/generator/API.mli
index c5bba8c2..96626c9b 100644
--- a/generator/API.mli
+++ b/generator/API.mli
@@ -52,6 +52,7 @@ and
| BytesPersistOut of string * string
| Closure of closure (** function pointer + void *opaque *)
| Enum of string * enum (** enum/union type, int in C *)
+| Extent64 of string (** extent descriptor, struct nbd_extent in C *)
| Fd of string (** file descriptor *)
| Flags of string * flags (** flags, uint32_t in C *)
| Int of string (** small int *)
diff --git a/generator/API.ml b/generator/API.ml
index 02c1260d..1da1ec53 100644
--- a/generator/API.ml
+++ b/generator/API.ml
@@ -42,6 +42,7 @@
| BytesPersistOut of string * string
| Closure of closure
| Enum of string * enum
+| Extent64 of string
| Fd of string
| Flags of string * flags
| Int of string
@@ -157,6 +158,14 @@ let extent_closure =
"nr_entries");
CBMutable (Int "error") ]
}
+let extent64_closure = {
+ cbname = "extent64";
+ cbargs = [ CBString "metacontext";
+ CBUInt64 "offset";
+ CBArrayAndLen (Extent64 "entries",
+ "nr_entries");
+ CBMutable (Int "error") ]
+}
let list_closure = {
cbname = "list";
cbargs = [ CBString "name"; CBString "description" ]
@@ -166,7 +175,8 @@ let context_closure =
cbargs = [ CBString "name" ]
}
let all_closures = [ chunk_closure; completion_closure;
- debug_closure; extent_closure; list_closure;
+ debug_closure; extent_closure; extent64_closure;
+ list_closure;
context_closure ]
(* Enums. *)
diff --git a/generator/C.ml b/generator/C.ml
index f772117c..d8472153 100644
--- a/generator/C.ml
+++ b/generator/C.ml
@@ -94,6 +94,7 @@ let
| Closure { cbname } ->
[ sprintf "%s_callback" cbname; sprintf "%s_user_data" cbname ]
| Enum (n, _) -> [n]
+ | Extent64 n -> [n]
| Fd n -> [n]
| Flags (n, _) -> [n]
| Int n -> [n]
@@ -129,7 +130,7 @@ let
(* list of strings should be marked as non-null *)
| StringList n -> [ true ]
(* numeric and other non-pointer types are not able to be null *)
- | Bool _ | Closure _ | Enum _ | Fd _ | Flags _
+ | Bool _ | Closure _ | Enum _ | Extent64 _ | Fd _ | Flags _
| Int _ | Int64 _ | SizeT _
| UInt _ | UInt32 _ | UInt64 _ | UIntPtr _ -> [ false ]
@@ -191,6 +192,9 @@ and
| Enum (n, _) ->
if types then pr "int ";
pr "%s" n
+ | Extent64 n ->
+ if types then pr "nbd_extent ";
+ pr "%s" n
| Flags (n, _) ->
if types then pr "uint32_t ";
pr "%s" n
@@ -305,6 +309,11 @@ and
pr "%s, " n;
if types then pr "size_t ";
pr "%s" len
+ | CBArrayAndLen (Extent64 n, len) ->
+ if types then pr "nbd_extent *";
+ pr "%s, " n;
+ if types then pr "size_t ";
+ pr "%s" len
| CBArrayAndLen _ -> assert false
| CBBytesIn (n, len) ->
if types then pr "const void *";
@@ -477,6 +486,13 @@ let
pr "extern int nbd_get_errno (void);\n";
pr "#define LIBNBD_HAVE_NBD_GET_ERRNO 1\n";
pr "\n";
+ pr "/* This is used in the callback for nbd_block_status_64.\n";
+ pr " */\n";
+ pr "typedef struct {\n";
+ pr " uint64_t length;\n";
+ pr " uint64_t flags;\n";
+ pr "} nbd_extent;\n";
+ pr "\n";
print_closure_structs ();
List.iter (
fun (name, { args; optargs; ret }) ->
@@ -740,7 +756,7 @@ let
pr " char *%s_printable =\n" n;
pr " nbd_internal_printable_string_list (%s);\n" n
| BytesOut _ | BytesPersistOut _
- | Bool _ | Closure _ | Enum _ | Flags _ | Fd _ | Int _
+ | Bool _ | Closure _ | Enum _ | Extent64 _ | Flags _ | Fd _ | Int _
| Int64 _ | SizeT _
| SockAddrAndLen _ | UInt _ | UInt32 _ | UInt64 _ | UIntPtr _ -> ()
) args;
@@ -766,6 +782,7 @@ let
pr " %s=\\\"%%s\\\" %s=%%zu" n count
| Closure { cbname } -> pr " %s=%%s" cbname
| Enum (n, _) -> pr " %s=%%d" n
+ | Extent64 _ -> assert false (* only used in extent64_closure *)
| Flags (n, _) -> pr " %s=0x%%x" n
| Fd n | Int n -> pr " %s=%%d" n
| Int64 n -> pr " %s=%%\"PRIi64\"" n
@@ -804,6 +821,7 @@ let
pr "%s_printable ? %s_printable : \"\", %s" n n count
| Closure _ -> pr "\"<fun>\""
| Enum (n, _) -> pr "%s" n
+ | Extent64 _ -> assert false (* only used in extent64_closure *)
| Flags (n, _) -> pr "%s" n
| Fd n | Int n | Int64 n | SizeT n -> pr "%s" n
| SockAddrAndLen (_, len) -> pr "(int) %s" len
@@ -836,7 +854,7 @@ let
| StringList n ->
pr " free (%s_printable);\n" n
| BytesOut _ | BytesPersistOut _
- | Bool _ | Closure _ | Enum _ | Flags _ | Fd _ | Int _
+ | Bool _ | Closure _ | Enum _ | Extent64 _ | Flags _ | Fd _ | Int _
| Int64 _ | SizeT _
| SockAddrAndLen _ | UInt _ | UInt32 _ | UInt64 _ | UIntPtr _ -> ()
) args;
diff --git a/generator/GoLang.ml b/generator/GoLang.ml
index 4ab6b262..8922812b 100644
--- a/generator/GoLang.ml
+++ b/generator/GoLang.ml
@@ -49,6 +49,7 @@ let
| BytesPersistOut (n, len) -> n
| Closure { cbname } -> cbname
| Enum (n, _) -> n
+ | Extent64 n -> n
| Fd n -> n
| Flags (n, _) -> n
| Int n -> n
@@ -71,6 +72,7 @@ let
| BytesPersistOut _ -> "AioBuffer"
| Closure { cbname } -> sprintf "%sCallback" (camel_case cbname)
| Enum (_, { enum_prefix }) -> camel_case enum_prefix
+ | Extent64 _ -> assert false (* only used in extent64_closure *)
| Fd _ -> "int"
| Flags (_, { flag_prefix }) -> camel_case flag_prefix
| Int _ -> "int"
@@ -262,6 +264,7 @@ let
pr " c_%s.user_data = C.alloc_cbid(C.long(%s_cbid))\n" cbname cbname
| Enum (n, _) ->
pr " c_%s := C.int (%s)\n" n n
+ | Extent64 _ -> assert false (* only used in extent64_closure *)
| Fd n ->
pr " c_%s := C.int (%s)\n" n n
| Flags (n, _) ->
@@ -334,6 +337,7 @@ let
| BytesPersistOut (n, len) -> pr ", c_%s, c_%s" n len
| Closure { cbname } -> pr ", c_%s" cbname
| Enum (n, _) -> pr ", c_%s" n
+ | Extent64 _ -> assert false (* only used in extent64_closure *)
| Fd n -> pr ", c_%s" n
| Flags (n, _) -> pr ", c_%s" n
| Int n -> pr ", c_%s" n
@@ -524,6 +528,18 @@ let
copy(ret, s)
return ret
}
+
+func copy_extent_array (entries *C.nbd_extent, count C.size_t) []LibnbdExtent {
+ unsafePtr := unsafe.Pointer(entries)
+ arrayPtr := (*[1 << 20]C.nbd_extent)(unsafePtr)
+ slice := arrayPtr[:count:count]
+ ret := make([]LibnbdExtent, count)
+ for i := 0; i < int (count); i++ {
+ ret[i].Length = uint64 (slice[i].length)
+ ret[i].Flags = uint64 (slice[i].flags)
+ }
+ return ret
+}
";
List.iter (
@@ -537,6 +553,8 @@ let
match cbarg with
| CBArrayAndLen (UInt32 n, _) ->
pr "%s []uint32" n;
+ | CBArrayAndLen (Extent64 n, _) ->
+ pr "%s []LibnbdExtent" n;
| CBBytesIn (n, len) ->
pr "%s []byte" n;
| CBInt n ->
@@ -563,6 +581,8 @@ let
match cbarg with
| CBArrayAndLen (UInt32 n, count) ->
pr "%s *C.uint32_t, %s C.size_t" n count
+ | CBArrayAndLen (Extent64 n, count) ->
+ pr "%s *C.nbd_extent, %s C.size_t" n count
| CBBytesIn (n, len) ->
pr "%s unsafe.Pointer, %s C.size_t" n len
| CBInt n ->
@@ -605,6 +625,8 @@ let
match cbarg with
| CBArrayAndLen (UInt32 n, count) ->
pr "copy_uint32_array (%s, %s)" n count
+ | CBArrayAndLen (Extent64 n, count) ->
+ pr "copy_extent_array (%s, %s)" n count
| CBBytesIn (n, len) ->
pr "C.GoBytes (%s, C.int (%s))" n len
| CBInt n ->
@@ -756,6 +778,8 @@ let
match cbarg with
| CBArrayAndLen (UInt32 n, count) ->
pr "uint32_t *%s, size_t %s" n count
+ | CBArrayAndLen (Extent64 n, count) ->
+ pr "nbd_extent *%s, size_t %s" n count
| CBBytesIn (n, len) ->
pr "void *%s, size_t %s" n len
| CBInt n ->
diff --git a/generator/OCaml.ml b/generator/OCaml.ml
index edb81f25..ea3b044a 100644
--- a/generator/OCaml.ml
+++ b/generator/OCaml.ml
@@ -44,6 +44,7 @@ and
| Closure { cbargs } ->
sprintf "(%s)" (ocaml_closuredecl_to_string cbargs)
| Enum (_, { enum_prefix }) -> sprintf "%s.t" enum_prefix
+ | Extent64 _ -> "extent"
| Fd _ -> "Unix.file_descr"
| Flags (_, { flag_prefix }) -> sprintf "%s.t list" flag_prefix
| Int _ -> "int"
@@ -102,6 +103,7 @@ let
| BytesPersistOut (n, len) -> n
| Closure { cbname } -> cbname
| Enum (n, _) -> n
+ | Extent64 n -> n
| Fd n -> n
| Flags (n, _) -> n
| Int n -> n
@@ -147,6 +149,9 @@ let
type cookie = int64
+type extent = int64 * int64
+(** Length and flags of an extent in block_status_64 callback. *)
+
";
List.iter (
@@ -268,6 +273,7 @@ let
exception Error of string * Unix.error option
exception Closed of string
type cookie = int64
+type extent = int64 * int64
(* Give the exceptions names so that they can be raised from the C code. *)
let () =
@@ -498,7 +504,8 @@ let
let argnames =
List.map (
function
- | CBArrayAndLen (UInt32 n, _) | CBBytesIn (n, _)
+ | CBArrayAndLen (UInt32 n, _) | CBArrayAndLen (Extent64 n, _)
+ | CBBytesIn (n, _)
| CBInt n | CBInt64 n
| CBMutable (Int n) | CBString n | CBUInt n | CBUInt64 n ->
n ^ "v"
@@ -531,6 +538,14 @@ let
pr "%s %s,\n" indent n;
pr "%s %s\n" indent count;
pr "%s);\n" indent
+ | CBArrayAndLen (Extent64 n, count) ->
+ pr " %sv = " n;
+ let fncol = output_column () in
+ let indent = spaces fncol in
+ pr "nbd_internal_ocaml_alloc_extent64_array (\n";
+ pr "%s %s,\n" indent n;
+ pr "%s %s\n" indent count;
+ pr "%s);\n" indent
| CBBytesIn (n, len) ->
pr " %sv = caml_alloc_initialized_string (%s, %s);\n" n len n
| CBInt n | CBUInt n ->
@@ -554,7 +569,7 @@ let
List.iter (
function
- | CBArrayAndLen (UInt32 _, _)
+ | CBArrayAndLen (_, _)
| CBBytesIn _
| CBInt _
| CBInt64 _
@@ -563,7 +578,7 @@ let
| CBUInt64 _ -> ()
| CBMutable (Int n) ->
pr " *%s = Int_val (Field (%sv, 0));\n" n n
- | CBArrayAndLen _ | CBMutable _ -> assert false
+ | CBMutable _ -> assert false
) cbargs;
pr " if (Is_exception_result (rv)) {\n";
@@ -578,6 +593,7 @@ let
pr "}\n";
pr "\n";
pr "static int\n";
+ pr "__attribute__ ((unused)) /* XXX temporary hack */\n";
pr "%s_wrapper " cbname;
C.print_cbarg_list ~wrap:true cbargs;
pr "\n";
@@ -695,6 +711,7 @@ let
pr " %s_callback.free = free_user_data;\n" cbname
| Enum (n, { enum_prefix }) ->
pr " int %s = %s_val (%sv);\n" n enum_prefix n
+ | Extent64 _ -> assert false (* only used in extent64_closure *)
| Fd n ->
pr " /* OCaml Unix.file_descr is just an int, at least on Unix. */\n";
pr " int %s = Int_val (%sv);\n" n n
@@ -780,6 +797,7 @@ let
| BytesPersistOut _
| Closure _
| Enum _
+ | Extent64 _
| Fd _
| Flags _
| Int _
diff --git a/generator/Python.ml b/generator/Python.ml
index c81878de..ccac5fed 100644
--- a/generator/Python.ml
+++ b/generator/Python.ml
@@ -158,6 +158,7 @@ let
let print_python_closure_wrapper { cbname; cbargs } =
pr "/* Wrapper for %s callback. */\n" cbname;
pr "static int\n";
+ pr "__attribute__ ((unused)) /* XXX temporary hack */\n";
pr "%s_wrapper " cbname;
C.print_cbarg_list ~wrap:true cbargs;
pr "\n";
@@ -170,6 +171,7 @@ let
List.iter (
function
| CBArrayAndLen (UInt32 n, _)
+ | CBArrayAndLen (Extent64 n, _)
| CBBytesIn (n, _)
| CBMutable (Int n) ->
pr " PyObject *py_%s = NULL;\n" n
@@ -187,6 +189,16 @@ let
pr " if (!py_e_%s) { PyErr_PrintEx (0); goto out; }\n" n;
pr " PyList_SET_ITEM (py_%s, i_%s, py_e_%s);\n" n n n;
pr " }\n"
+ | CBArrayAndLen (Extent64 n, len) ->
+ pr " py_%s = PyList_New (%s);\n" n len;
+ pr " size_t i_%s;\n" n;
+ pr " for (i_%s = 0; i_%s < %s; ++i_%s) {\n" n n len n;
+ pr " PyObject *py_e_%s = Py_BuildValue (\"OO\",\n" n;
+ pr " PyLong_FromUnsignedLong (%s[i_%s].length),\n" n n;
+ pr " PyLong_FromUnsignedLong (%s[i_%s].flags));\n" n n;
+ pr " if (!py_e_%s) { PyErr_PrintEx (0); goto out; }\n" n;
+ pr " PyList_SET_ITEM (py_%s, i_%s, py_e_%s);\n" n n n;
+ pr " }\n"
| CBBytesIn (n, len) ->
pr " py_%s = nbd_internal_py_get_subview (data->view, %s, %s);\n" n n len;
pr " if (!py_%s) { PyErr_PrintEx (0); goto out; }\n" n
@@ -206,6 +218,7 @@ let
List.map (
function
| CBArrayAndLen (UInt32 n, _) -> "O", sprintf "py_%s" n
+ | CBArrayAndLen (Extent64 n, _) -> "O", sprintf "py_%s" n
| CBBytesIn (n, _) -> "O", sprintf "py_%s" n
| CBInt n -> "i", n
| CBInt64 n -> "L", n
@@ -254,7 +267,8 @@ let
pr " out:\n";
List.iter (
function
- | CBArrayAndLen (UInt32 n, _) ->
+ | CBArrayAndLen (UInt32 n, _)
+ | CBArrayAndLen (Extent64 n, _) ->
pr " Py_XDECREF (py_%s);\n" n
| CBBytesIn (n, _) ->
pr " Py_XDECREF (py_%s);\n" n
@@ -307,6 +321,7 @@ let
pr ".callback = %s_wrapper, .free = free_user_data" cbname);
pr " };\n"
| Enum (n, _) -> pr " int %s;\n" n
+ | Extent64 _ -> assert false (* only used in extent64_closure *)
| Flags (n, _) ->
pr " uint32_t %s_u32;\n" n;
pr " unsigned int %s; /* really uint32_t */\n" n
@@ -363,6 +378,7 @@ let
"O", sprintf "&%s" n, sprintf "py_%s->buf, py_%s->len" n n
| Closure { cbname } -> "O", sprintf "&py_%s_fn" cbname, cbname
| Enum (n, _) -> "i", sprintf "&%s" n, n
+ | Extent64 _ -> assert false (* only used in extent64_closure *)
| Flags (n, _) -> "I", sprintf "&%s" n, sprintf "%s_u32" n
| Fd n | Int n -> "i", sprintf "&%s" n, n
| Int64 n -> "L", sprintf "&%s" n, sprintf "%s_i64" n
@@ -454,6 +470,7 @@ let
pr " if (!chunk_user_data->view) goto out;\n"
)
| Enum _ -> ()
+ | Extent64 _ -> ()
| Flags (n, _) -> pr " %s_u32 = %s;\n" n n
| Fd _ | Int _ -> ()
| Int64 n -> pr " %s_i64 = %s;\n" n n
@@ -552,6 +569,7 @@ let
| Closure { cbname } ->
pr " free_user_data (%s_user_data);\n" cbname
| Enum _ -> ()
+ | Extent64 _ -> ()
| Flags _ -> ()
| Fd _ | Int _ -> ()
| Int64 _ -> ()
@@ -881,6 +899,7 @@ let
| BytesPersistOut (n, _) -> n, None
| Closure { cbname } -> cbname, None
| Enum (n, _) -> n, None
+ | Extent64 _ -> assert false (* only used in extent64_closure *)
| Flags (n, _) -> n, None
| Fd n | Int n -> n, None
| Int64 n -> n, None
diff --git a/ocaml/helpers.c b/ocaml/helpers.c
index 3361a696..09666daf 100644
--- a/ocaml/helpers.c
+++ b/ocaml/helpers.c
@@ -133,6 +133,26 @@ nbd_internal_ocaml_alloc_i64_from_u32_array (uint32_t *a, size_t len)
CAMLreturn (rv);
}
+value
+nbd_internal_ocaml_alloc_extent64_array (nbd_extent *a, size_t len)
+{
+ CAMLparam0 ();
+ CAMLlocal3 (s, v, rv);
+ size_t i;
+
+ rv = caml_alloc (len, 0);
+ for (i = 0; i < len; ++i) {
+ s = caml_alloc (2, 0);
+ v = caml_copy_int64 (a[i].length);
+ Store_field (s, 0, v);
+ v = caml_copy_int64 (a[i].flags);
+ Store_field (s, 1, v);
+ Store_field (rv, i, s);
+ }
+
+ CAMLreturn (rv);
+}
+
/* Convert a Unix.sockaddr to a C struct sockaddr. */
void
nbd_internal_unix_sockaddr_to_sa (value sockaddrv,
diff --git a/ocaml/nbd-c.h b/ocaml/nbd-c.h
index e3abb912..adcdd15a 100644
--- a/ocaml/nbd-c.h
+++ b/ocaml/nbd-c.h
@@ -62,6 +62,7 @@ extern void nbd_internal_ocaml_raise_closed (const char *func) Noreturn;
extern const char **nbd_internal_ocaml_string_list (value);
extern value nbd_internal_ocaml_alloc_i64_from_u32_array (uint32_t *, size_t);
+extern value nbd_internal_ocaml_alloc_extent64_array (nbd_extent *, size_t);
extern void nbd_internal_unix_sockaddr_to_sa (value, struct sockaddr_storage *,
socklen_t *);
extern void nbd_internal_ocaml_exception_in_wrapper (const char *, value);
diff --git a/golang/handle.go b/golang/handle.go
index 5fe4ed4f..0b126005 100644
--- a/golang/handle.go
+++ b/golang/handle.go
@@ -58,6 +58,12 @@ func (h *Libnbd) String() string {
return "&Libnbd{}"
}
+/* Used for block status callback. */
+type LibnbdExtent struct {
+ Length uint64 // length of the extent
+ Flags uint64 // flags describing properties of the extent
+}
+
/* All functions (except Close) return ([result,] LibnbdError). */
type LibnbdError struct {
Op string // operation which failed
--
2.40.1
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