7:07 p.m.
The next patch will add a new 'nbd_aio_pread_callback' function for
allowing the user more immediate access as each chunk of a structured
reply read is received. But before we do that, let's refactor the
command code. This includes a revert of 12843a1a, since the read
callback will need both a buffer and the user's opaque object at the
same time.
---
generator/states-reply-structured.c | 8 ++++----
lib/internal.h | 17 +++++++++++++----
lib/rw.c | 9 ++++++---
3 files changed, 23 insertions(+), 11 deletions(-)
diff --git a/generator/states-reply-structured.c b/generator/states-reply-structured.c
index 6740400..657106e 100644
--- a/generator/states-reply-structured.c
+++ b/generator/states-reply-structured.c
@@ -123,7 +123,7 @@
set_error (0, "invalid length in NBD_REPLY_TYPE_BLOCK_STATUS");
return -1;
}
- if (cmd->extent_fn == NULL) {
+ if (cmd->cb.fn.extent == NULL) {
SET_NEXT_STATE (%.DEAD);
set_error (0, "not expecting NBD_REPLY_TYPE_BLOCK_STATUS here");
return -1;
@@ -375,7 +375,7 @@
length = be32toh (h->sbuf.sr.structured_reply.length);
assert (cmd); /* guaranteed by CHECK */
- assert (cmd->extent_fn);
+ assert (cmd->cb.fn.extent);
assert (h->bs_entries);
assert (length >= 12);
@@ -401,8 +401,8 @@
if (meta_context) {
/* Call the caller's extent function. */
errno = 0;
- if (cmd->extent_fn (cmd->data, meta_context->name, cmd->offset,
- &h->bs_entries[1], (length-4) / 4) == -1)
+ if (cmd->cb.fn.extent (cmd->cb.opaque, meta_context->name,
cmd->offset,
+ &h->bs_entries[1], (length-4) / 4) == -1)
cmd->error = errno ? errno : EPROTO;
}
else
diff --git a/lib/internal.h b/lib/internal.h
index 1f8f789..cb0e170 100644
--- a/lib/internal.h
+++ b/lib/internal.h
@@ -231,7 +231,16 @@ struct socket {
const struct socket_ops *ops;
};
-typedef int (*extent_fn) (void *data, const char *metacontext, uint64_t offset, uint32_t
*entries, size_t nr_entries);
+typedef int (*extent_fn) (void *data, const char *metacontext, uint64_t offset,
+ uint32_t *entries, size_t nr_entries);
+
+struct command_cb {
+ void *opaque;
+ union {
+ extent_fn extent;
+ /* More to come */
+ } fn;
+};
struct command_in_flight {
struct command_in_flight *next;
@@ -240,8 +249,8 @@ struct command_in_flight {
uint64_t handle;
uint64_t offset;
uint32_t count;
- void *data; /* Buffer for read/write, opaque for block status */
- extent_fn extent_fn;
+ void *data; /* Buffer for read/write */
+ struct command_cb cb;
bool data_seen; /* For read, true if at least one data chunk seen */
uint32_t error; /* Local errno value */
};
@@ -300,7 +309,7 @@ extern const char *nbd_internal_name_of_nbd_cmd (uint16_t type);
extern int64_t nbd_internal_command_common (struct nbd_handle *h,
uint16_t flags, uint16_t type,
uint64_t offset, uint64_t count,
- void *data, extent_fn extent);
+ void *data, struct command_cb *cb);
/* socket.c */
struct socket *nbd_internal_socket_create (int fd);
diff --git a/lib/rw.c b/lib/rw.c
index ad9c8a0..dc81c57 100644
--- a/lib/rw.c
+++ b/lib/rw.c
@@ -143,7 +143,7 @@ int64_t
nbd_internal_command_common (struct nbd_handle *h,
uint16_t flags, uint16_t type,
uint64_t offset, uint64_t count, void *data,
- extent_fn extent)
+ struct command_cb *cb)
{
struct command_in_flight *cmd, *prev_cmd;
@@ -183,7 +183,8 @@ nbd_internal_command_common (struct nbd_handle *h,
cmd->offset = offset;
cmd->count = count;
cmd->data = data;
- cmd->extent_fn = extent;
+ if (cb)
+ cmd->cb = *cb;
/* If structured replies were negotiated then we trust the server to
* send back sufficient data to cover the whole buffer. It's tricky
@@ -360,6 +361,8 @@ nbd_unlocked_aio_block_status (struct nbd_handle *h,
void *data, extent_fn extent,
uint32_t flags)
{
+ struct command_cb cb = { .opaque = data, .fn.extent = extent, };
+
if (!h->structured_replies) {
set_error (ENOTSUP, "server does not support structured replies");
return -1;
@@ -383,5 +386,5 @@ nbd_unlocked_aio_block_status (struct nbd_handle *h,
}
return nbd_internal_command_common (h, flags, NBD_CMD_BLOCK_STATUS, offset,
- count, data, extent);
+ count, NULL, &cb);
}
--
2.20.1