Re: [Libguestfs] [libnbd PATCH v3 22/22] api: Add nbd_[aio_]block_status_filter()

As part of extending NBD to support 64-bit lengths, the protocol also added an option for servers to allow clients to request filtered responses to NBD_CMD_BLOCK_STATUS when more than one meta-context is negotiated (see NBD commit e6f3b94a). At the same time as this patch, qemu-nbd was taught to support and advertise this feature as a server, but does not utilize it as a client (qemu doesn't yet need to connect to multiple contexts at once). Thus, addding generic client support and enhancing the interop/ test in libnbd is needed to prove that the feature is viable and worth standardizing. --- lib/internal.h | 5 +- generator/API.ml | 71 +++++++++++++++-- generator/states-issue-command.c | 4 +- lib/aio.c | 7 +- lib/rw.c | 127 ++++++++++++++++++++++++++++++- interop/block-status-payload.c | 117 +++++++++++++++++++++++++++- interop/block-status-payload.sh | 14 +++- info/info-can.sh | 3 + 8 files changed, 336 insertions(+), 12 deletions(-) diff --git a/lib/internal.h b/lib/internal.h index 2948b77b..64921de9 100644 --- a/lib/internal.h +++ b/lib/internal.h @@ -73,6 +73,8 @@ struct meta_context { }; DEFINE_VECTOR_TYPE (meta_vector, struct meta_context); +DEFINE_VECTOR_TYPE(uint32_vector, uint32_t); + struct export { char *name; char *description; @@ -380,7 +382,8 @@ struct command { uint64_t cookie; uint64_t offset; uint64_t count; - void *data; /* Buffer for read/write */ + void *data; /* Buffer for read/write, uint32_vector* for status payload */ + uint32_vector *ids; /* For block status with payload */ struct command_cb cb; bool initialized; /* For read, true if getting a hole may skip memset */ uint32_t data_seen; /* For read, cumulative size of data chunks seen */ diff --git a/generator/API.ml b/generator/API.ml index 5a31ce3b..a26ed1da 100644 --- a/generator/API.ml +++ b/generator/API.ml @@ -2335,12 +2335,13 @@ "can_block_status_payload", { longdesc = "\ Returns true if the server supports the use of the C<LIBNBD_CMD_FLAG_PAYLOAD_LEN> flag to allow filtering of the -block status command. Returns +block status command (see L<nbd_block_status_filter(3)>). Returns false if the server does not. Note that this will never return true if L<nbd_get_extended_headers_negotiated(3)> is false." ^ non_blocking_test_call_description; see_also = [SectionLink "Flag calls"; Link "opt_info"; - Link "get_extended_headers_negotiated"]; + Link "get_extended_headers_negotiated"; + Link "block_status_filter"]; example = Some "examples/server-flags.c"; }; @@ -2409,6 +2410,10 @@ "can_meta_context", { meta contexts were requested but there is a missing or failed attempt at NBD_OPT_SET_META_CONTEXT during option negotiation. +If the server supports block status filtering (see +L<nbd_can_block_status_payload(3)>, this function must return +true for any filter name passed to L<nbd_block_status_filter(3)>. + The single parameter is the name of the metadata context, for example C<LIBNBD_CONTEXT_BASE_ALLOCATION>. B<E<lt>libnbd.hE<gt>> includes defined constants for well-known @@ -2941,9 +2946,12 @@ "block_status_64", { information about blocks beginning from the specified offset to be returned. The C<count> parameter is a hint: the server may choose to return less status, or the final block -may extend beyond the requested range. If multiple contexts +may extend beyond the requested range. When multiple contexts are supported, the number of blocks and cumulative length -of those blocks need not be identical between contexts. +of those blocks need not be identical between contexts; this +command generally returns the status of all negotiated contexts, +while some servers also support a filtered request (see +L<nbd_can_block_status_payload(3)>, L<nbd_block_status_filter(3)>). Note that not all servers can support a C<count> of 4GiB or larger; L<nbd_get_extended_headers_negotiated(3)> indicates which servers @@ -2993,11 +3001,38 @@ "block_status_64", { does not exceed C<count> bytes; however, libnbd does not validate that the server obeyed the flag." ^ strict_call_description; - see_also = [Link "block_status"; + see_also = [Link "block_status"; Link "block_status_filter"; Link "add_meta_context"; Link "can_meta_context"; Link "aio_block_status_64"; Link "set_strict_mode"]; }; + "block_status_filter", { + default_call with + args = [ UInt64 "count"; UInt64 "offset"; StringList "contexts"; + Closure extent64_closure ]; + optargs = [ OFlags ("flags", cmd_flags, Some ["REQ_ONE"; "PAYLOAD_LEN"]) ]; + ret = RErr; + permitted_states = [ Connected ]; + shortdesc = "send filtered block status command, with 64-bit callback"; + longdesc = "\ +Issue a filtered block status command to the NBD server. If +supported by the server (see L<nbd_can_block_status_payload(3)>), +this causes metadata context information about blocks beginning +from the specified offset to be returned, and with the result +limited to just the contexts specified in C<filter>. Note that +all strings in C<filter> must be supported by +L<nbd_can_meta_context(3)>. + +All other parameters to this function have the same semantics +as in L<nbd_block_status_64(3)>; except that for convenience, +the C<flags> parameter may additionally contain or omit +C<LIBNBD_CMD_FLAG_PAYLOAD_LEN>." +^ strict_call_description; + see_also = [Link "block_status_64"; + Link "can_block_status_payload"; Link "can_meta_context"; + Link "aio_block_status_filter"; Link "set_strict_mode"]; + }; + "poll", { default_call with args = [ Int "timeout" ]; ret = RInt; @@ -3667,6 +3702,30 @@ "aio_block_status_64", { Link "set_strict_mode"]; }; + "aio_block_status_filter", { + default_call with + args = [ UInt64 "count"; UInt64 "offset"; StringList "contexts"; + Closure extent64_closure ]; + optargs = [ OClosure completion_closure; + OFlags ("flags", cmd_flags, Some ["REQ_ONE"; "PAYLOAD_LEN"]) ]; + ret = RCookie; + permitted_states = [ Connected ]; + shortdesc = "send filtered block status command to the NBD server"; + longdesc = "\ +Send a filtered block status command to the NBD server. + +To check if the command completed, call L<nbd_aio_command_completed(3)>. +Or supply the optional C<completion_callback> which will be invoked +as described in L<libnbd(3)/Completion callbacks>. + +Other parameters behave as documented in L<nbd_block_status_filter(3)>." +^ strict_call_description; + see_also = [SectionLink "Issuing asynchronous commands"; + Link "aio_block_status_64"; Link "block_status_filter"; + Link "can_meta_context"; Link "can_block_status_payload"; + Link "set_strict_mode"]; + }; + "aio_get_fd", { default_call with args = []; ret = RFd; @@ -4201,6 +4260,8 @@ let first_version = "opt_extended_headers", (1, 18); "aio_opt_extended_headers", (1, 18); "can_block_status_payload", (1, 18); + "block_status_filter", (1, 18); + "aio_block_status_filter", (1, 18); (* These calls are proposed for a future version of libnbd, but * have not been added to any released version so far. diff --git a/generator/states-issue-command.c b/generator/states-issue-command.c index 79136b61..5307731d 100644 --- a/generator/states-issue-command.c +++ b/generator/states-issue-command.c @@ -84,7 +84,9 @@ ISSUE_COMMAND.PREPARE_WRITE_PAYLOAD: assert (h->cmds_to_issue != NULL); cmd = h->cmds_to_issue; assert (cmd->cookie == be64toh (h->req.compact.handle)); - if (cmd->type == NBD_CMD_WRITE) { + if (cmd->type == NBD_CMD_WRITE || + (h->extended_headers && cmd->type == NBD_CMD_BLOCK_STATUS && + cmd->flags & NBD_CMD_FLAG_PAYLOAD_LEN)) { h->wbuf = cmd->data; h->wlen = cmd->count; if (cmd->next && cmd->count < 64 * 1024) diff --git a/lib/aio.c b/lib/aio.c index a419ac32..77b20c32 100644 --- a/lib/aio.c +++ b/lib/aio.c @@ -32,8 +32,13 @@ void nbd_internal_retire_and_free_command (struct command *cmd) { /* Free the callbacks. */ - if (cmd->type == NBD_CMD_BLOCK_STATUS) + if (cmd->type == NBD_CMD_BLOCK_STATUS) { + if (cmd->ids) { + uint32_vector_reset (cmd->ids); + free (cmd->ids); + } FREE_CALLBACK (cmd->cb.fn.extent); + } if (cmd->type == NBD_CMD_READ) FREE_CALLBACK (cmd->cb.fn.chunk); FREE_CALLBACK (cmd->cb.completion); diff --git a/lib/rw.c b/lib/rw.c index bea55fa1..db6bc0bc 100644 --- a/lib/rw.c +++ b/lib/rw.c @@ -242,6 +242,26 @@ nbd_unlocked_block_status_64 (struct nbd_handle *h, return wait_for_command (h, cookie); } +/* Issue a filtered block status command and wait for the reply. */ +int +nbd_unlocked_block_status_filter (struct nbd_handle *h, + uint64_t count, uint64_t offset, + char **filter, + nbd_extent64_callback *extent64, + uint32_t flags) +{ + int64_t cookie; + nbd_completion_callback c = NBD_NULL_COMPLETION; + + cookie = nbd_unlocked_aio_block_status_filter (h, count, offset, filter, + extent64, &c, flags); + if (cookie == -1) + return -1; + + assert (CALLBACK_IS_NULL (*extent64)); + return wait_for_command (h, cookie); +} + /* count_err represents the errno to return if bounds check fail */ int64_t nbd_internal_command_common (struct nbd_handle *h, @@ -250,6 +270,7 @@ nbd_internal_command_common (struct nbd_handle *h, void *data, struct command_cb *cb) { struct command *cmd; + uint32_vector *ids = NULL; if (h->disconnect_request) { set_error (EINVAL, "cannot request more commands after NBD_CMD_DISC"); @@ -297,10 +318,23 @@ nbd_internal_command_common (struct nbd_handle *h, } break; + case NBD_CMD_BLOCK_STATUS: + if (data) { + ids = data; + count = ids->len * sizeof (uint32_t); + data = ids->ptr; + if (count > MAX_REQUEST_SIZE || + (h->strict & LIBNBD_STRICT_PAYLOAD && count > h->payload_maximum)) { + set_error (ERANGE, "filter set too large"); + goto err; + } + break; + } + /* fallthrough */ + default: /* Other commands are limited by the 32 bit field in the command * structure on the wire, unless extended headers were negotiated. */ - default: if (!h->extended_headers && count > UINT32_MAX) { set_error (ERANGE, "request too large: maximum request size is %" PRIu32, UINT32_MAX); @@ -320,6 +354,7 @@ nbd_internal_command_common (struct nbd_handle *h, cmd->offset = offset; cmd->count = count; cmd->data = data; + cmd->ids = ids; if (cb) cmd->cb = *cb; @@ -364,8 +399,13 @@ nbd_internal_command_common (struct nbd_handle *h, err: /* Since we did not queue the command, we must free the callbacks. */ if (cb) { - if (type == NBD_CMD_BLOCK_STATUS) + if (type == NBD_CMD_BLOCK_STATUS) { + if (ids) { + uint32_vector_reset (ids); + free (ids); + } FREE_CALLBACK (cb->fn.extent); + } if (type == NBD_CMD_READ) FREE_CALLBACK (cb->fn.chunk); FREE_CALLBACK (cb->completion); @@ -609,3 +649,86 @@ nbd_unlocked_aio_block_status_64 (struct nbd_handle *h, return nbd_internal_command_common (h, flags, NBD_CMD_BLOCK_STATUS, offset, count, EINVAL, NULL, &cb); } + +int64_t +nbd_unlocked_aio_block_status_filter (struct nbd_handle *h, + uint64_t count, uint64_t offset, + char **filter, + nbd_extent64_callback *extent64, + nbd_completion_callback *completion, + uint32_t flags) +{ + struct command_cb cb = { .fn.extent = *extent64, + .completion = *completion }; + uint32_vector *ids; + char *name; + size_t i; + + /* Because this affects wire format, it is more convenient to manage + * PAYLOAD_LEN by what was negotiated than to require the user to + * have to set it correctly. + */ + if (!h->extended_headers) { + set_error (ENOTSUP, "server does not support extended headers"); + return -1; + } + flags |= LIBNBD_CMD_FLAG_PAYLOAD_LEN; + + if (h->strict & LIBNBD_STRICT_COMMANDS) { + if (nbd_unlocked_can_block_status_payload (h) != 1) { + set_error (EINVAL, + "server does not support the block status payload flag"); + return -1; + } + + if (!h->meta_valid || h->meta_contexts.len == 0) { + set_error (ENOTSUP, "did not negotiate any metadata contexts, " + "either you did not call nbd_add_meta_context before " + "connecting or the server does not support it"); + return -1; + } + } + + ids = calloc (1, sizeof *ids); + if (ids == NULL) { + set_error (errno, "calloc"); + return -1; + } + if (uint32_vector_append (ids, htobe32 (count >> 32)) == -1 || + uint32_vector_append (ids, htobe32 (count)) == -1) { + set_error (errno, "realloc"); + goto fail; + } + + /* O(n^2) search - hopefully filter and negotiated contexts are both small */

+ for ( ; (name = *filter) != NULL; filter++) { + if (!h->meta_valid) { + set_error (EINVAL, "context %s not negotiated", name); + goto fail; + } + for (i = 0; i < h->meta_contexts.len; i++) { + struct meta_context *meta = &h->meta_contexts.ptr[i]; + if (strcmp (name, meta->name) == 0) { + if (uint32_vector_append (ids, htobe32 (meta->context_id)) == -1) { + set_error (errno, "realloc"); + goto fail; + } + break; + } + } + if (i == h->meta_contexts.len) { + set_error (EINVAL, "context %s not negotiated", name); + goto fail; + } + } + + SET_CALLBACK_TO_NULL (*extent64); + SET_CALLBACK_TO_NULL (*completion); + return nbd_internal_command_common (h, flags, NBD_CMD_BLOCK_STATUS, offset, + count, EINVAL, ids, &cb); + + fail: + uint32_vector_reset (ids); + free (ids); + return -1; +} diff --git a/interop/block-status-payload.c b/interop/block-status-payload.c index 9603dfe5..704b25aa 100644 --- a/interop/block-status-payload.c +++ b/interop/block-status-payload.c @@ -54,11 +54,26 @@ cb (void *opaque, const char *metacontext, uint64_t offset, return 0; } +static char ** +list (unsigned int use) +{ + static const char *array[ARRAY_SIZE (contexts) + 1]; + size_t i, j; + + assert (use < 1 << ARRAY_SIZE (contexts)); + for (i = j = 0; i < ARRAY_SIZE (contexts); i++) + if (use & (1 << i)) + array[j++] = contexts[i]; + array[j] = NULL; + return (char **) array; +} + int main (int argc, char *argv[]) { struct nbd_handle *nbd; int64_t exportsize; + uint64_t bytes_sent; unsigned int seen; size_t i; int r; @@ -114,7 +129,107 @@ main (int argc, char *argv[]) } assert (seen == 0xf); - /* FIXME: Test filtered calls once the API is added */ + /* Filtering with all contexts listed, same effect as unfilitered call */ + seen = 0; + if (nbd_block_status_filter (nbd, exportsize, 0, list (0xf), + (nbd_extent64_callback) { .callback = cb, + .user_data = &seen }, + 0) == -1) { + fprintf (stderr, "%s\n", nbd_get_error ()); + exit (EXIT_FAILURE); + } + assert (seen == 0xf); + + /* Filtering with just two out of four contexts; test optional flag */ + seen = 0; + if (nbd_block_status_filter (nbd, exportsize, 0, list (0x5), + (nbd_extent64_callback) { .callback = cb, + .user_data = &seen }, + LIBNBD_CMD_FLAG_PAYLOAD_LEN) == -1) { + fprintf (stderr, "%s\n", nbd_get_error ()); + exit (EXIT_FAILURE); + } + assert (seen == 0x5); + + /* Filtering with one context, near end of file (to make sure the + * payload length isn't confused with the effect length) + */ + seen = 0; + if (nbd_block_status_filter (nbd, 1, exportsize - 1, list (0x2), + (nbd_extent64_callback) { .callback = cb, + .user_data = &seen }, + 0) == -1) { + fprintf (stderr, "%s\n", nbd_get_error ()); + exit (EXIT_FAILURE); + } + assert (seen == 0x2); + + /* Filtering with no contexts - pointless, so qemu rejects it */ + bytes_sent = nbd_stats_bytes_sent (nbd); + seen = 0; + if (nbd_block_status_filter (nbd, exportsize, 0, list (0x0), + (nbd_extent64_callback) { .callback = cb, + .user_data = &seen }, + 0) != -1) { + fprintf (stderr, "expecting block status failure\n"); + exit (EXIT_FAILURE); + } + assert (seen == 0x0); + if (nbd_get_errno () != EINVAL) { + fprintf (stderr, "expecting EINVAL after block status failure\n"); + exit (EXIT_FAILURE); + } + if (nbd_stats_bytes_sent (nbd) <= bytes_sent) { + fprintf (stderr, "expecting server-side rejection of bad request\n"); + exit (EXIT_FAILURE); + } + + /* Giving unknown string triggers EINVAL from libnbd */ + bytes_sent = nbd_stats_bytes_sent (nbd); + seen = 0; + { + const char *bogus[] = { "qemu:dirty-bitmap:bitmap2", NULL }; + if (nbd_block_status_filter (nbd, exportsize, 0, (char **) bogus, + (nbd_extent64_callback) { .callback = cb, + .user_data = &seen }, + 0) != -1) { + fprintf (stderr, "expecting block status failure\n"); + exit (EXIT_FAILURE); + } + } + if (nbd_get_errno () != EINVAL) { + fprintf (stderr, "expecting EINVAL after block status failure\n"); + exit (EXIT_FAILURE); + } + assert (seen == 0x0); + if (nbd_stats_bytes_sent (nbd) != bytes_sent) { + fprintf (stderr, "expecting client-side rejection of bad request\n"); + exit (EXIT_FAILURE); + } + + /* Giving same string twice triggers EINVAL from qemu */ + seen = 0; + { + const char *dupes[] = { "base:allocation", "base:allocation", NULL }; + if (nbd_block_status_filter (nbd, exportsize, 0, (char **) dupes, + (nbd_extent64_callback) { .callback = cb, + .user_data = &seen }, + 0) != -1) { + fprintf (stderr, "expecting block status failure\n"); + exit (EXIT_FAILURE); + } + } + if (nbd_get_errno () != EINVAL) { + fprintf (stderr, "expecting EINVAL after block status failure\n"); + exit (EXIT_FAILURE); + } + assert (seen == 0x0); + if (nbd_stats_bytes_sent (nbd) <= bytes_sent) { + fprintf (stderr, "expecting server-side rejection of bad request\n"); + exit (EXIT_FAILURE); + } + + /* Done */ if (nbd_shutdown (nbd, 0) == -1) { fprintf (stderr, "%s\n", nbd_get_error ()); exit (EXIT_FAILURE); diff --git a/interop/block-status-payload.sh b/interop/block-status-payload.sh index a12cfc8a..0e6681b6 100755 --- a/interop/block-status-payload.sh +++ b/interop/block-status-payload.sh @@ -49,6 +49,7 @@ args = ["qemu-nbd", "-f", "qcow2", "-A", "-B", "bitmap0", "-B", "bitmap1", h.connect_systemd_socket_activation(args) assert h.aio_is_negotiating() is True assert h.get_extended_headers_negotiated() is False + # Flag not available until info or go try: h.can_block_status_payload() @@ -58,7 +59,18 @@ except nbd.Error: h.opt_info() assert h.can_block_status_payload() is False assert h.can_meta_context("base:allocation") is True -h.opt_abort() + +# Filter request not allowed if not advertised +def f(): + assert False +h.opt_go() +assert h.can_block_status_payload() is False +try: + h.block_status_filter(0, 512, ["base:allocation"], f) + assert False +except nbd.Error: + pass +h.shutdown() ' # Conditional part of test: if qemu is new enough to support extended diff --git a/info/info-can.sh b/info/info-can.sh index 8154d1ce..097837d2 100755 --- a/info/info-can.sh +++ b/info/info-can.sh @@ -38,6 +38,9 @@ requires bash -c "nbdkit sh --dump-plugin | grep has_can_cache=1" # and oldstyle never, but that feels like depending a bit too much on # the implementation. +# --can block-status-payload is not supported by nbdkit yet. Testing +# is done during interop with new-enough qemu. + # --can structured-reply is not a per-export setting, but rather # something set on the server as a whole.