Upcoming additions to support NBD 64-bit effect lengths allow for the
possibility to distinguish between payload length (capped at 32M) and
effect length (up to 63 bits). Without that extension, only the
NBD_CMD_WRITE request has a payload; but with the extension, it makes
sense to allow at least NBD_CMD_BLOCK_STATUS to have both a payload
and effect length (where the payload is a limited-size struct that in
turns gives the real effect length as well as a subset of known ids
for which status is requested). Other future NBD commands may also
have a request payload, so the 64-bit extension introduces a new
NBD_CMD_FLAG_PAYLOAD_LEN that distinguishes between whether the header
length is a payload length or an effect length, rather than
hard-coding the decision based on the command. Note that we do not
support the payload version of BLOCK_STATUS yet.
For this patch, no semantic change is intended for a compliant client.
For a non-compliant client, it is possible that the error behavior
changes (a different message, a change on whether the connection is
killed or remains alive for the next command, or so forth), in part
because req->complete is set later on some paths, but all errors
should still be handled gracefully.
Signed-off-by: Eric Blake <ebl...@redhat.com>
---
v4: less indentation on several 'if's [Vladimir]
---
nbd/server.c | 76 ++++++++++++++++++++++++++++++------------------
nbd/trace-events | 1 +
2 files changed, 49 insertions(+), 28 deletions(-)
diff --git a/nbd/server.c b/nbd/server.c
index 4ac05d0cd7b..d7dc29f0445 100644
--- a/nbd/server.c
+++ b/nbd/server.c
@@ -2329,6 +2329,8 @@ static int coroutine_fn
nbd_co_receive_request(NBDRequestData *req, NBDRequest *
Error **errp)
{
NBDClient *client = req->client;
+ bool extended_with_payload;
+ unsigned payload_len = 0;
int valid_flags;
int ret;
@@ -2342,48 +2344,63 @@ static int coroutine_fn
nbd_co_receive_request(NBDRequestData *req, NBDRequest *
trace_nbd_co_receive_request_decode_type(request->cookie, request->type,
nbd_cmd_lookup(request->type));
- if (request->type != NBD_CMD_WRITE) {
- /* No payload, we are ready to read the next request. */
- req->complete = true;
- }
-
if (request->type == NBD_CMD_DISC) {
/* Special case: we're going to disconnect without a reply,
* whether or not flags, from, or len are bogus */
+ req->complete = true;
return -EIO;
}
- if (request->type == NBD_CMD_READ || request->type == NBD_CMD_WRITE ||
- request->type == NBD_CMD_CACHE)
- {
- if (request->len > NBD_MAX_BUFFER_SIZE) {
- error_setg(errp, "len (%" PRIu64" ) is larger than max len (%u)",
- request->len, NBD_MAX_BUFFER_SIZE);
- return -EINVAL;
+ /* Payload and buffer handling. */
+ extended_with_payload = client->mode >= NBD_MODE_EXTENDED &&
+ (request->flags & NBD_CMD_FLAG_PAYLOAD_LEN);
+ if ((request->type == NBD_CMD_READ || request->type == NBD_CMD_WRITE ||
+ request->type == NBD_CMD_CACHE || extended_with_payload) &&
+ request->len > NBD_MAX_BUFFER_SIZE) {
+ error_setg(errp, "len (%" PRIu64" ) is larger than max len (%u)",
+ request->len, NBD_MAX_BUFFER_SIZE);
+ return -EINVAL;
+ }
+
+ if (request->type == NBD_CMD_WRITE || extended_with_payload) {
+ payload_len = request->len;
+ if (request->type != NBD_CMD_WRITE) {
+ /*
+ * For now, we don't support payloads on other
+ * commands; but we can keep the connection alive.
+ */
+ request->len = 0;
+ } else if (client->mode >= NBD_MODE_EXTENDED &&
+ !extended_with_payload) {
+ /* The client is noncompliant. Trace it, but proceed. */
+ trace_nbd_co_receive_ext_payload_compliance(request->from,
+ request->len);
}
+ }
- if (request->type != NBD_CMD_CACHE) {
- req->data = blk_try_blockalign(client->exp->common.blk,
- request->len);
- if (req->data == NULL) {
- error_setg(errp, "No memory");
- return -ENOMEM;
- }
+ if (request->type == NBD_CMD_WRITE || request->type == NBD_CMD_READ) {
+ req->data = blk_try_blockalign(client->exp->common.blk,
+ request->len);
+ if (req->data == NULL) {
+ error_setg(errp, "No memory");
+ return -ENOMEM;
}
}
- if (request->type == NBD_CMD_WRITE) {
- assert(request->len <= NBD_MAX_BUFFER_SIZE);
- if (nbd_read(client->ioc, req->data, request->len, "CMD_WRITE data",
- errp) < 0)
- {
+ if (payload_len) {
+ if (req->data) {
+ ret = nbd_read(client->ioc, req->data, payload_len,
+ "CMD_WRITE data", errp);
+ } else {
+ ret = nbd_drop(client->ioc, payload_len, errp);
+ }
+ if (ret < 0) {
return -EIO;
}
- req->complete = true;
-
trace_nbd_co_receive_request_payload_received(request->cookie,
- request->len);
+ payload_len);
}
+ req->complete = true;
/* Sanity checks. */
if (client->exp->nbdflags & NBD_FLAG_READ_ONLY &&
@@ -2413,7 +2430,10 @@ static int coroutine_fn
nbd_co_receive_request(NBDRequestData *req, NBDRequest *
client->check_align);
}
valid_flags = NBD_CMD_FLAG_FUA;
- if (request->type == NBD_CMD_READ && client->mode >= NBD_MODE_STRUCTURED) {
+ if (request->type == NBD_CMD_WRITE && client->mode >= NBD_MODE_EXTENDED) {
+ valid_flags |= NBD_CMD_FLAG_PAYLOAD_LEN;
+ } else if (request->type == NBD_CMD_READ &&
+ client->mode >= NBD_MODE_STRUCTURED) {
valid_flags |= NBD_CMD_FLAG_DF;
} else if (request->type == NBD_CMD_WRITE_ZEROES) {
valid_flags |= NBD_CMD_FLAG_NO_HOLE | NBD_CMD_FLAG_FAST_ZERO;
diff --git a/nbd/trace-events b/nbd/trace-events
index 3338da2be2a..6a34d7f027a 100644
--- a/nbd/trace-events
+++ b/nbd/trace-events
@@ -71,6 +71,7 @@ nbd_co_send_extents(uint64_t cookie, unsigned int extents,
uint32_t id, uint64_t
nbd_co_send_chunk_error(uint64_t cookie, int err, const char *errname, const
char *msg) "Send structured error reply: cookie = %" PRIu64 ", error = %d (%s),
msg = '%s'"
nbd_co_receive_request_decode_type(uint64_t cookie, uint16_t type, const char
*name) "Decoding type: cookie = %" PRIu64 ", type = %" PRIu16 " (%s)"
nbd_co_receive_request_payload_received(uint64_t cookie, uint64_t len)
"Payload received: cookie = %" PRIu64 ", len = %" PRIu64
+nbd_co_receive_ext_payload_compliance(uint64_t from, uint64_t len) "client
sent non-compliant write without payload flag: from=0x%" PRIx64 ", len=0x%"
PRIx64
nbd_co_receive_align_compliance(const char *op, uint64_t from, uint64_t len,
uint32_t align) "client sent non-compliant unaligned %s request: from=0x%"
PRIx64 ", len=0x%" PRIx64 ", align=0x%" PRIx32
nbd_trip(void) "Reading request"
--
2.40.1
