Eric Blake
2023-Jun-08 13:56 UTC
[Libguestfs] [PATCH v4 24/24] nbd/server: Add FLAG_PAYLOAD support to CMD_BLOCK_STATUS
Allow a client to request a subset of negotiated meta contexts. For
example, a client may ask to use a single connection to learn about
both block status and dirty bitmaps, but where the dirty bitmap
queries only need to be performed on a subset of the disk; forcing the
server to compute that information on block status queries in the rest
of the disk is wasted effort (both at the server, and on the amount of
traffic sent over the wire to be parsed and ignored by the client).
Qemu as an NBD client never requests to use more than one meta
context, so it has no need to use block status payloads. Testing this
instead requires support from libnbd, which CAN access multiple meta
contexts in parallel from a single NBD connection; an interop test
submitted to the libnbd project at the same time as this patch
demonstrates the feature working, as well as testing some corner cases
(for example, when the payload length is longer than the export
length), although other corner cases (like passing the same id
duplicated) requires a protocol fuzzer because libnbd is not wired up
to break the protocol that badly.
This also includes tweaks to 'qemu-nbd --list' to show when a server
is advertising the capability, and to the testsuite to reflect the
addition to that output.
Signed-off-by: Eric Blake <eblake at redhat.com>
---
docs/interop/nbd.txt | 2 +-
nbd/server.c | 99 ++++++++++++++++++-
qemu-nbd.c | 1 +
nbd/trace-events | 1 +
tests/qemu-iotests/223.out | 12 +--
tests/qemu-iotests/307.out | 10 +-
.../tests/nbd-qemu-allocation.out | 2 +-
7 files changed, 111 insertions(+), 16 deletions(-)
diff --git a/docs/interop/nbd.txt b/docs/interop/nbd.txt
index abaf4c28a96..83d85ce8d13 100644
--- a/docs/interop/nbd.txt
+++ b/docs/interop/nbd.txt
@@ -69,4 +69,4 @@ NBD_CMD_BLOCK_STATUS for "qemu:dirty-bitmap:",
NBD_CMD_CACHE
NBD_CMD_FLAG_FAST_ZERO
* 5.2: NBD_CMD_BLOCK_STATUS for "qemu:allocation-depth"
* 7.1: NBD_FLAG_CAN_MULTI_CONN for shareable writable exports
-* 8.1: NBD_OPT_EXTENDED_HEADERS
+* 8.1: NBD_OPT_EXTENDED_HEADERS, NBD_FLAG_BLOCK_STATUS_PAYLOAD
diff --git a/nbd/server.c b/nbd/server.c
index 308846fe46b..696afcf5c46 100644
--- a/nbd/server.c
+++ b/nbd/server.c
@@ -512,6 +512,9 @@ static int nbd_negotiate_handle_export_name(NBDClient
*client, bool no_zeroes,
if (client->mode >= NBD_MODE_STRUCTURED) {
myflags |= NBD_FLAG_SEND_DF;
}
+ if (client->mode >= NBD_MODE_EXTENDED &&
client->contexts.count) {
+ myflags |= NBD_FLAG_BLOCK_STAT_PAYLOAD;
+ }
trace_nbd_negotiate_new_style_size_flags(client->exp->size, myflags);
stq_be_p(buf, client->exp->size);
stw_be_p(buf + 8, myflags);
@@ -699,6 +702,10 @@ static int nbd_negotiate_handle_info(NBDClient *client,
Error **errp)
if (client->mode >= NBD_MODE_STRUCTURED) {
myflags |= NBD_FLAG_SEND_DF;
}
+ if (client->mode >= NBD_MODE_EXTENDED &&
+ (client->contexts.count || client->opt == NBD_OPT_INFO)) {
+ myflags |= NBD_FLAG_BLOCK_STAT_PAYLOAD;
+ }
trace_nbd_negotiate_new_style_size_flags(exp->size, myflags);
stq_be_p(buf, exp->size);
stw_be_p(buf + 8, myflags);
@@ -2424,6 +2431,81 @@ static int coroutine_fn nbd_co_send_bitmap(NBDClient
*client,
return nbd_co_send_extents(client, request, ea, last, context_id, errp);
}
+/*
+ * nbd_co_block_status_payload_read
+ * Called when a client wants a subset of negotiated contexts via a
+ * BLOCK_STATUS payload. Check the payload for valid length and
+ * contents. On success, return 0 with request updated to effective
+ * length. If request was invalid but payload consumed, return 0 with
+ * request->len and request->contexts->count set to 0 (which will
+ * trigger an appropriate NBD_EINVAL response later on). On I/O
+ * error, return -EIO.
+ */
+static int
+nbd_co_block_status_payload_read(NBDClient *client, NBDRequest *request,
+ Error **errp)
+{
+ int payload_len = request->len;
+ g_autofree char *buf = NULL;
+ size_t count, i, nr_bitmaps;
+ uint32_t id;
+
+ assert(request->len <= NBD_MAX_BUFFER_SIZE);
+ assert(client->contexts.exp == client->exp);
+ nr_bitmaps = client->exp->nr_export_bitmaps;
+ request->contexts = g_new0(NBDMetaContexts, 1);
+ request->contexts->exp = client->exp;
+
+ if (payload_len % sizeof(uint32_t) ||
+ payload_len < sizeof(NBDBlockStatusPayload) ||
+ payload_len > (sizeof(NBDBlockStatusPayload) +
+ sizeof(id) * client->contexts.count)) {
+ goto skip;
+ }
+
+ buf = g_malloc(payload_len);
+ if (nbd_read(client->ioc, buf, payload_len,
+ "CMD_BLOCK_STATUS data", errp) < 0) {
+ return -EIO;
+ }
+ trace_nbd_co_receive_request_payload_received(request->cookie,
+ payload_len);
+ request->contexts->bitmaps = g_new0(bool, nr_bitmaps);
+ count = (payload_len - sizeof(NBDBlockStatusPayload)) / sizeof(id);
+ payload_len = 0;
+
+ for (i = 0; i < count; i++) {
+ id = ldl_be_p(buf + sizeof(NBDBlockStatusPayload) + sizeof(id) * i);
+ if (id == NBD_META_ID_BASE_ALLOCATION) {
+ if (request->contexts->base_allocation) {
+ goto skip;
+ }
+ request->contexts->base_allocation = true;
+ } else if (id == NBD_META_ID_ALLOCATION_DEPTH) {
+ if (request->contexts->allocation_depth) {
+ goto skip;
+ }
+ request->contexts->allocation_depth = true;
+ } else {
+ if (id - NBD_META_ID_DIRTY_BITMAP > nr_bitmaps ||
+ request->contexts->bitmaps[id -
NBD_META_ID_DIRTY_BITMAP]) {
+ goto skip;
+ }
+ request->contexts->bitmaps[id - NBD_META_ID_DIRTY_BITMAP] =
true;
+ }
+ }
+
+ request->len = ldq_be_p(buf);
+ request->contexts->count = count;
+ return 0;
+
+ skip:
+ trace_nbd_co_receive_block_status_payload_compliance(request->from,
+ request->len);
+ request->len = request->contexts->count = 0;
+ return nbd_drop(client->ioc, payload_len, errp);
+}
+
/* nbd_co_receive_request
* Collect a client request. Return 0 if request looks valid, -EIO to drop
* connection right away, -EAGAIN to indicate we were interrupted and the
@@ -2470,7 +2552,13 @@ static int coroutine_fn
nbd_co_receive_request(NBDRequestData *req, NBDRequest *
if (request->type == NBD_CMD_WRITE || extended_with_payload) {
payload_len = request->len;
- if (request->type != NBD_CMD_WRITE) {
+ if (request->type == NBD_CMD_BLOCK_STATUS) {
+ ret = nbd_co_block_status_payload_read(client, request, errp);
+ if (ret < 0) {
+ return ret;
+ }
+ payload_len = 0;
+ } else if (request->type != NBD_CMD_WRITE) {
/*
* For now, we don't support payloads on other
* commands; but we can keep the connection alive.
@@ -2491,7 +2579,8 @@ static int coroutine_fn
nbd_co_receive_request(NBDRequestData *req, NBDRequest *
error_setg(errp, "No memory");
return -ENOMEM;
}
- } else if (request->type == NBD_CMD_BLOCK_STATUS) {
+ } else if (request->type == NBD_CMD_BLOCK_STATUS &&
+ !extended_with_payload) {
request->contexts = &client->contexts;
}
@@ -2547,6 +2636,9 @@ static int coroutine_fn
nbd_co_receive_request(NBDRequestData *req, NBDRequest *
valid_flags |= NBD_CMD_FLAG_NO_HOLE | NBD_CMD_FLAG_FAST_ZERO;
} else if (request->type == NBD_CMD_BLOCK_STATUS) {
valid_flags |= NBD_CMD_FLAG_REQ_ONE;
+ if (client->mode >= NBD_MODE_EXTENDED &&
client->contexts.count) {
+ valid_flags |= NBD_CMD_FLAG_PAYLOAD_LEN;
+ }
}
if (request->flags & ~valid_flags) {
error_setg(errp, "unsupported flags for command %s (got
0x%x)",
@@ -2712,7 +2804,8 @@ static coroutine_fn int nbd_handle_request(NBDClient
*client,
"discard failed", errp);
case NBD_CMD_BLOCK_STATUS:
- if (!request->len) {
+ assert(request->contexts);
+ if (!request->len && !(request->flags &
NBD_CMD_FLAG_PAYLOAD_LEN)) {
return nbd_send_generic_reply(client, request, -EINVAL,
"need non-zero length",
errp);
}
diff --git a/qemu-nbd.c b/qemu-nbd.c
index 1d155fc2c66..cbca0eeee62 100644
--- a/qemu-nbd.c
+++ b/qemu-nbd.c
@@ -222,6 +222,7 @@ static int qemu_nbd_client_list(SocketAddress *saddr,
QCryptoTLSCreds *tls,
[NBD_FLAG_SEND_RESIZE_BIT] = "resize",
[NBD_FLAG_SEND_CACHE_BIT] = "cache",
[NBD_FLAG_SEND_FAST_ZERO_BIT] = "fast-zero",
+ [NBD_FLAG_BLOCK_STAT_PAYLOAD_BIT] =
"block-status-payload",
};
printf(" size: %" PRIu64 "\n", list[i].size);
diff --git a/nbd/trace-events b/nbd/trace-events
index 51bfb129c95..a1af6d003b4 100644
--- a/nbd/trace-events
+++ b/nbd/trace-events
@@ -70,6 +70,7 @@ nbd_co_send_chunk_read(uint64_t cookie, uint64_t offset, void
*data, size_t size
nbd_co_send_chunk_read_hole(uint64_t cookie, uint64_t offset, size_t size)
"Send structured read hole reply: cookie = %" PRIu64 ", offset =
%" PRIu64 ", len = %zu"
nbd_co_send_extents(uint64_t cookie, unsigned int extents, uint32_t id,
uint64_t length, int last) "Send block status reply: cookie = %"
PRIu64 ", extents = %u, context = %d (extents cover %" PRIu64 "
bytes, last chunk = %d)"
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_block_status_payload_compliance(uint64_t from, int len)
"client sent unusable block status payload: from=0x%" PRIx64 ",
len=0x%x"
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
diff --git a/tests/qemu-iotests/223.out b/tests/qemu-iotests/223.out
index b98582c38ea..b38f0b7963b 100644
--- a/tests/qemu-iotests/223.out
+++ b/tests/qemu-iotests/223.out
@@ -83,7 +83,7 @@ exports available: 0
exports available: 3
export: 'n'
size: 4194304
- flags: 0x58f ( readonly flush fua df multi cache )
+ flags: 0x158f ( readonly flush fua df multi cache block-status-payload )
min block: 1
opt block: 4096
max block: 33554432
@@ -94,7 +94,7 @@ exports available: 3
export: 'n2'
description: some text
size: 4194304
- flags: 0xded ( flush fua trim zeroes df multi cache fast-zero )
+ flags: 0x1ded ( flush fua trim zeroes df multi cache fast-zero
block-status-payload )
min block: 1
opt block: 4096
max block: 33554432
@@ -104,7 +104,7 @@ exports available: 3
qemu:dirty-bitmap:b2
export: 'n3'
size: 4194304
- flags: 0x58f ( readonly flush fua df multi cache )
+ flags: 0x158f ( readonly flush fua df multi cache block-status-payload )
min block: 1
opt block: 4096
max block: 33554432
@@ -205,7 +205,7 @@ exports available: 0
exports available: 3
export: 'n'
size: 4194304
- flags: 0x58f ( readonly flush fua df multi cache )
+ flags: 0x158f ( readonly flush fua df multi cache block-status-payload )
min block: 1
opt block: 4096
max block: 33554432
@@ -216,7 +216,7 @@ exports available: 3
export: 'n2'
description: some text
size: 4194304
- flags: 0xded ( flush fua trim zeroes df multi cache fast-zero )
+ flags: 0x1ded ( flush fua trim zeroes df multi cache fast-zero
block-status-payload )
min block: 1
opt block: 4096
max block: 33554432
@@ -226,7 +226,7 @@ exports available: 3
qemu:dirty-bitmap:b2
export: 'n3'
size: 4194304
- flags: 0x58f ( readonly flush fua df multi cache )
+ flags: 0x158f ( readonly flush fua df multi cache block-status-payload )
min block: 1
opt block: 4096
max block: 33554432
diff --git a/tests/qemu-iotests/307.out b/tests/qemu-iotests/307.out
index 2b9a6a67a1a..f645f3315f8 100644
--- a/tests/qemu-iotests/307.out
+++ b/tests/qemu-iotests/307.out
@@ -15,7 +15,7 @@ wrote 4096/4096 bytes at offset 0
exports available: 1
export: 'fmt'
size: 67108864
- flags: 0x58f ( readonly flush fua df multi cache )
+ flags: 0x158f ( readonly flush fua df multi cache block-status-payload )
min block: XXX
opt block: XXX
max block: XXX
@@ -44,7 +44,7 @@ exports available: 1
exports available: 1
export: 'fmt'
size: 67108864
- flags: 0x58f ( readonly flush fua df multi cache )
+ flags: 0x158f ( readonly flush fua df multi cache block-status-payload )
min block: XXX
opt block: XXX
max block: XXX
@@ -76,7 +76,7 @@ exports available: 1
exports available: 2
export: 'fmt'
size: 67108864
- flags: 0x58f ( readonly flush fua df multi cache )
+ flags: 0x158f ( readonly flush fua df multi cache block-status-payload )
min block: XXX
opt block: XXX
max block: XXX
@@ -86,7 +86,7 @@ exports available: 2
export: 'export1'
description: This is the writable second export
size: 67108864
- flags: 0xded ( flush fua trim zeroes df multi cache fast-zero )
+ flags: 0x1ded ( flush fua trim zeroes df multi cache fast-zero
block-status-payload )
min block: XXX
opt block: XXX
max block: XXX
@@ -113,7 +113,7 @@ exports available: 1
export: 'export1'
description: This is the writable second export
size: 67108864
- flags: 0xded ( flush fua trim zeroes df multi cache fast-zero )
+ flags: 0x1ded ( flush fua trim zeroes df multi cache fast-zero
block-status-payload )
min block: XXX
opt block: XXX
max block: XXX
diff --git a/tests/qemu-iotests/tests/nbd-qemu-allocation.out
b/tests/qemu-iotests/tests/nbd-qemu-allocation.out
index 659276032b0..794d1bfce62 100644
--- a/tests/qemu-iotests/tests/nbd-qemu-allocation.out
+++ b/tests/qemu-iotests/tests/nbd-qemu-allocation.out
@@ -17,7 +17,7 @@ wrote 2097152/2097152 bytes at offset 1048576
exports available: 1
export: ''
size: 4194304
- flags: 0x48f ( readonly flush fua df cache )
+ flags: 0x148f ( readonly flush fua df cache block-status-payload )
min block: 1
opt block: 4096
max block: 33554432
--
2.40.1
Eric Blake
2023-Jun-08 19:19 UTC
[Libguestfs] [PATCH v4 24/24] nbd/server: Add FLAG_PAYLOAD support to CMD_BLOCK_STATUS
On Thu, Jun 08, 2023 at 08:56:53AM -0500, Eric Blake wrote:> Allow a client to request a subset of negotiated meta contexts. For > example, a client may ask to use a single connection to learn about > both block status and dirty bitmaps, but where the dirty bitmap > queries only need to be performed on a subset of the disk; forcing the > server to compute that information on block status queries in the rest > of the disk is wasted effort (both at the server, and on the amount of > traffic sent over the wire to be parsed and ignored by the client). > > Qemu as an NBD client never requests to use more than one meta > context, so it has no need to use block status payloads. Testing this > instead requires support from libnbd, which CAN access multiple meta > contexts in parallel from a single NBD connection; an interop test > submitted to the libnbd project at the same time as this patch > demonstrates the feature working, as well as testing some corner cases > (for example, when the payload length is longer than the export > length), although other corner cases (like passing the same id > duplicated) requires a protocol fuzzer because libnbd is not wired up > to break the protocol that badly. > > This also includes tweaks to 'qemu-nbd --list' to show when a server > is advertising the capability, and to the testsuite to reflect the > addition to that output. > > Signed-off-by: Eric Blake <eblake at redhat.com> > ---> +++ b/nbd/server.c > @@ -512,6 +512,9 @@ static int nbd_negotiate_handle_export_name(NBDClient *client, bool no_zeroes, > if (client->mode >= NBD_MODE_STRUCTURED) { > myflags |= NBD_FLAG_SEND_DF; > } > + if (client->mode >= NBD_MODE_EXTENDED && client->contexts.count) { > + myflags |= NBD_FLAG_BLOCK_STAT_PAYLOAD; > + }This one's awkward. At the last minute, I changed what went into upstream NBD to state that a client that successfully negotiates extended headers MUST NOT use NBD_OPT_EXPORT_NAME, which means this branch should never fire for a compliant client. I don't think it hurts to leave this in, but it does point out that I am missing code (either here or in 17/24) that at least logs when we detect a non-compliant client trying to connect with the wrong command. -- Eric Blake, Principal Software Engineer Red Hat, Inc. +1-919-301-3266 Virtualization: qemu.org | libvirt.org
Vladimir Sementsov-Ogievskiy
2023-Jun-27 19:42 UTC
[Libguestfs] [PATCH v4 24/24] nbd/server: Add FLAG_PAYLOAD support to CMD_BLOCK_STATUS
On 08.06.23 16:56, Eric Blake wrote:> Allow a client to request a subset of negotiated meta contexts. For > example, a client may ask to use a single connection to learn about > both block status and dirty bitmaps, but where the dirty bitmap > queries only need to be performed on a subset of the disk; forcing the > server to compute that information on block status queries in the rest > of the disk is wasted effort (both at the server, and on the amount of > traffic sent over the wire to be parsed and ignored by the client). > > Qemu as an NBD client never requests to use more than one meta > context, so it has no need to use block status payloads. Testing this > instead requires support from libnbd, which CAN access multiple meta > contexts in parallel from a single NBD connection; an interop test > submitted to the libnbd project at the same time as this patch > demonstrates the feature working, as well as testing some corner cases > (for example, when the payload length is longer than the export > length), although other corner cases (like passing the same id > duplicated) requires a protocol fuzzer because libnbd is not wired up > to break the protocol that badly. > > This also includes tweaks to 'qemu-nbd --list' to show when a server > is advertising the capability, and to the testsuite to reflect the > addition to that output. > > Signed-off-by: Eric Blake <eblake at redhat.com> > ---[..]> +static int > +nbd_co_block_status_payload_read(NBDClient *client, NBDRequest *request, > + Error **errp) > +{ > + int payload_len = request->len; > + g_autofree char *buf = NULL; > + size_t count, i, nr_bitmaps; > + uint32_t id; > + > + assert(request->len <= NBD_MAX_BUFFER_SIZE); > + assert(client->contexts.exp == client->exp); > + nr_bitmaps = client->exp->nr_export_bitmaps; > + request->contexts = g_new0(NBDMetaContexts, 1); > + request->contexts->exp = client->exp; > + > + if (payload_len % sizeof(uint32_t) || > + payload_len < sizeof(NBDBlockStatusPayload) || > + payload_len > (sizeof(NBDBlockStatusPayload) + > + sizeof(id) * client->contexts.count)) { > + goto skip; > + } > + > + buf = g_malloc(payload_len); > + if (nbd_read(client->ioc, buf, payload_len, > + "CMD_BLOCK_STATUS data", errp) < 0) { > + return -EIO; > + } > + trace_nbd_co_receive_request_payload_received(request->cookie, > + payload_len); > + request->contexts->bitmaps = g_new0(bool, nr_bitmaps); > + count = (payload_len - sizeof(NBDBlockStatusPayload)) / sizeof(id); > + payload_len = 0; > + > + for (i = 0; i < count; i++) { > + id = ldl_be_p(buf + sizeof(NBDBlockStatusPayload) + sizeof(id) * i); > + if (id == NBD_META_ID_BASE_ALLOCATION) { > + if (request->contexts->base_allocation) { > + goto skip; > + } > + request->contexts->base_allocation = true; > + } else if (id == NBD_META_ID_ALLOCATION_DEPTH) { > + if (request->contexts->allocation_depth) { > + goto skip; > + } > + request->contexts->allocation_depth = true; > + } else {maybe, int ind = id - NBD_META_ID_DIRTY_BITMAP;> + if (id - NBD_META_ID_DIRTY_BITMAP > nr_bitmaps ||>= ?> + request->contexts->bitmaps[id - NBD_META_ID_DIRTY_BITMAP]) { > + goto skip; > + } > + request->contexts->bitmaps[id - NBD_META_ID_DIRTY_BITMAP] = true; > + } > + } > + > + request->len = ldq_be_p(buf); > + request->contexts->count = count; > + return 0; > + > + skip: > + trace_nbd_co_receive_block_status_payload_compliance(request->from, > + request->len); > + request->len = request->contexts->count = 0; > + return nbd_drop(client->ioc, payload_len, errp); > +} > + > /* nbd_co_receive_request > * Collect a client request. Return 0 if request looks valid, -EIO to drop > * connection right away, -EAGAIN to indicate we were interrupted and the > @@ -2470,7 +2552,13 @@ static int coroutine_fn nbd_co_receive_request(NBDRequestData *req, NBDRequest *[..]> @@ -2712,7 +2804,8 @@ static coroutine_fn int nbd_handle_request(NBDClient *client, > "discard failed", errp); > > case NBD_CMD_BLOCK_STATUS: > - if (!request->len) { > + assert(request->contexts); > + if (!request->len && !(request->flags & NBD_CMD_FLAG_PAYLOAD_LEN)) {why not error-out for len=0 in case of payload?> return nbd_send_generic_reply(client, request, -EINVAL, > "need non-zero length", errp); > } > diff --git a/qemu-nbd.c b/qemu-nbd.c > index 1d155fc2c66..cbca0eeee62 100644-- Best regards, Vladimir