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* docs: fix references to docs/devel/tracing.rstStefano Garzarella2021-06-021-1/+1
| | | | | | | | | | | | | | | Commit e50caf4a5c ("tracing: convert documentation to rST") converted docs/devel/tracing.txt to docs/devel/tracing.rst. We still have several references to the old file, so let's fix them with the following command: sed -i s/tracing.txt/tracing.rst/ $(git grep -l docs/devel/tracing.txt) Signed-off-by: Stefano Garzarella <sgarzare@redhat.com> Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com> Message-Id: <20210517151702.109066-2-sgarzare@redhat.com> Signed-off-by: Thomas Huth <thuth@redhat.com>
* trace: Remove trailing newline in eventsPhilippe Mathieu-Daudé2019-09-181-2/+2
| | | | | | | | | | | | | | | | | | | | While the tracing framework does not forbid trailing newline in events format string, using them lead to confuse output. It is the responsibility of the backend to properly end an event line. Some of our formats have trailing newlines, remove them. [Fixed typo in commit description reported by Eric Blake <eblake@redhat.com> --Stefan] Reviewed-by: John Snow <jsnow@redhat.com> Reviewed-by: Kevin Wolf <kwolf@redhat.com> Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com> Message-id: 20190916095121.29506-2-philmd@redhat.com Message-Id: <20190916095121.29506-2-philmd@redhat.com> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
* nbd: Tolerate more errors to structured reply requestEric Blake2019-09-051-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | A server may have a reason to reject a request for structured replies, beyond just not recognizing them as a valid request; similarly, it may have a reason for rejecting a request for a meta context. It doesn't hurt us to continue talking to such a server; otherwise 'qemu-nbd --list' of such a server fails to display all available details about the export. Encountered when temporarily tweaking nbdkit to reply with NBD_REP_ERR_POLICY. Present since structured reply support was first added (commit d795299b reused starttls handling, but starttls is different in that we can't fall back to other behavior on any error). Note that for an unencrypted client trying to connect to a server that requires encryption, this defers the point of failure to when we finally execute a strict command (such as NBD_OPT_GO or NBD_OPT_LIST), now that the intermediate NBD_OPT_STRUCTURED_REPLY does not diagnose NBD_REP_ERR_TLS_REQD as fatal; but as the protocol eventually gets us to a command where we can't continue onwards, the changed error message doesn't cause any security concerns. Signed-off-by: Eric Blake <eblake@redhat.com> Message-Id: <20190824172813.29720-3-eblake@redhat.com> Reviewed-by: Daniel P. Berrangé <berrange@redhat.com> [eblake: fix iotest 233]
* nbd/server: Trace client noncompliance on unaligned requestsEric Blake2019-04-081-0/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | We've recently added traces for clients to flag server non-compliance; let's do the same for servers to flag client non-compliance. According to the spec, if the client requests NBD_INFO_BLOCK_SIZE, it is promising to send all requests aligned to those boundaries. Of course, if the client does not request NBD_INFO_BLOCK_SIZE, then it made no promises so we shouldn't flag anything; and because we are willing to handle clients that made no promises (the spec allows us to use NBD_REP_ERR_BLOCK_SIZE_REQD if we had been unwilling), we already have to handle unaligned requests (which the block layer already does on our behalf). So even though the spec allows us to return EINVAL for clients that promised to behave, it's easier to always answer unaligned requests. Still, flagging non-compliance can be useful in debugging a client that is trying to be maximally portable. Qemu as client used to have one spot where it sent non-compliant requests: if the server sends an unaligned reply to NBD_CMD_BLOCK_STATUS, and the client was iterating over the entire disk, the next request would start at that unaligned point; this was fixed in commit a39286dd when the client was taught to work around server non-compliance; but is equally fixed if the server is patched to not send unaligned replies in the first place (yes, qemu 4.0 as server still has few such bugs, although they will be patched in 4.1). Fortunately, I did not find any more spots where qemu as client was non-compliant. I was able to test the patch by using the following hack to convince qemu-io to run various unaligned commands, coupled with serving 512-byte alignment by intentionally omitting '-f raw' on the server while viewing server traces. | diff --git i/nbd/client.c w/nbd/client.c | index 427980bdd22..1858b2aac35 100644 | --- i/nbd/client.c | +++ w/nbd/client.c | @@ -449,6 +449,7 @@ static int nbd_opt_info_or_go(QIOChannel *ioc, uint32_t opt, | nbd_send_opt_abort(ioc); | return -1; | } | + info->min_block = 1;//hack | if (!is_power_of_2(info->min_block)) { | error_setg(errp, "server minimum block size %" PRIu32 | " is not a power of two", info->min_block); Signed-off-by: Eric Blake <eblake@redhat.com> Message-Id: <20190403030526.12258-3-eblake@redhat.com> [eblake: address minor review nits] Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
* trace-events: Delete unused trace pointsMarkus Armbruster2019-03-221-2/+0Star
| | | | | | | | | | | | | | | | | | | | | Tracked down with cleanup-trace-events.pl. Funnies requiring manual post-processing: * block.c and blockdev.c trace points are in block/trace-events. * hw/block/nvme.c uses the preprocessor to hide its trace point use from cleanup-trace-events.pl. * include/hw/xen/xen_common.h trace points are in hw/xen/trace-events. * net/colo-compare and net/filter-rewriter.c use pseudo trace points colo_compare_udp_miscompare and colo_filter_rewriter_debug to guard debug code. Signed-off-by: Markus Armbruster <armbru@redhat.com> Message-id: 20190314180929.27722-5-armbru@redhat.com Message-Id: <20190314180929.27722-5-armbru@redhat.com> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
* trace-events: Shorten file names in commentsMarkus Armbruster2019-03-221-3/+3
| | | | | | | | | | | | | | | We spell out sub/dir/ in sub/dir/trace-events' comments pointing to source files. That's because when trace-events got split up, the comments were moved verbatim. Delete the sub/dir/ part from these comments. Gets rid of several misspellings. Signed-off-by: Markus Armbruster <armbru@redhat.com> Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com> Message-id: 20190314180929.27722-3-armbru@redhat.com Message-Id: <20190314180929.27722-3-armbru@redhat.com> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
* trace-events: Consistently point to docs/devel/tracing.txtMarkus Armbruster2019-03-221-0/+2
| | | | | | | | | | | | | | Almost all trace-events point to docs/devel/tracing.txt in a comment right at the beginning. Touch up the ones that don't. [Updated with Markus' new commit description wording. --Stefan] Signed-off-by: Markus Armbruster <armbru@redhat.com> Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com> Message-id: 20190314180929.27722-2-armbru@redhat.com Message-Id: <20190314180929.27722-2-armbru@redhat.com> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
* nbd/client: Refactor nbd_opt_go() to support NBD_OPT_INFOEric Blake2019-01-211-4/+4
| | | | | | | | | | Rename the function to nbd_opt_info_or_go() with an added parameter and slight changes to comments and trace messages, in order to reuse the function for NBD_OPT_INFO. Signed-off-by: Eric Blake <eblake@redhat.com> Message-Id: <20190117193658.16413-17-eblake@redhat.com> Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
* nbd/client: Split handshake into two functionsEric Blake2019-01-211-1/+1
| | | | | | | | | | | | | | | | | | | | An upcoming patch will add the ability for qemu-nbd to list the services provided by an NBD server. Share the common code of the TLS handshake by splitting the initial exchange into a separate function, leaving only the export handling in the original function. Functionally, there should be no change in behavior in this patch, although some of the code motion may be difficult to follow due to indentation changes (view with 'git diff -w' for a smaller changeset). I considered an enum for the return code coordinating state between the two functions, but in the end just settled with ample comments. Signed-off-by: Eric Blake <eblake@redhat.com> Reviewed-by: Richard W.M. Jones <rjones@redhat.com> Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Message-Id: <20190117193658.16413-15-eblake@redhat.com>
* nbd/client: Split out nbd_receive_one_meta_context()Eric Blake2019-01-211-1/+1
| | | | | | | | | | | | | Extract portions of nbd_negotiate_simple_meta_context() to a new function nbd_receive_one_meta_context() that copies the pattern of nbd_receive_list() for performing the argument validation of one reply. The error message when the server replies with more than one context changes slightly, but that shouldn't happen in the common case. Signed-off-by: Eric Blake <eblake@redhat.com> Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Message-Id: <20190117193658.16413-13-eblake@redhat.com>
* nbd/client: Split out nbd_send_meta_query()Eric Blake2019-01-211-1/+1
| | | | | | | | | | | | | Refactor nbd_negotiate_simple_meta_context() to pull out the code that can be reused to send a LIST request for 0 or 1 query. No semantic change. The old comment about 'sizeof(uint32_t)' being equivalent to '/* number of queries */' is no longer needed, now that we are computing 'sizeof(queries)' instead. Signed-off-by: Eric Blake <eblake@redhat.com> Reviewed-by: Richard W.M. Jones <rjones@redhat.com> Message-Id: <20190117193658.16413-12-eblake@redhat.com> Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
* nbd/client: Move export name into NBDExportInfoEric Blake2019-01-211-1/+1
| | | | | | | | | | | | | | | | | | | Refactor the 'name' parameter of nbd_receive_negotiate() from being a separate parameter into being part of the in-out 'info'. This also spills over to a simplification of nbd_opt_go(). The main driver for this refactoring is that an upcoming patch would like to add support to qemu-nbd to list information about all exports available on a server, where the name(s) will be provided by the server instead of the client. But another benefit is that we can now allow the client to explicitly specify the empty export name "" even when connecting to an oldstyle server (even if qemu is no longer such a server after commit 7f7dfe2a). Signed-off-by: Eric Blake <eblake@redhat.com> Reviewed-by: Richard W.M. Jones <rjones@redhat.com> Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Message-Id: <20190117193658.16413-10-eblake@redhat.com>
* nbd/client: Refactor nbd_receive_list()Eric Blake2019-01-211-0/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Right now, nbd_receive_list() is only called by nbd_receive_query_exports(), which in turn is only called if the server lacks NBD_OPT_GO but has working option negotiation, and is merely used as a quality-of-implementation trick since servers can't give decent errors for NBD_OPT_EXPORT_NAME. However, servers that lack NBD_OPT_GO are becoming increasingly rare (nbdkit was a latecomer, in Aug 2018, but qemu has been such a server since commit f37708f6 in July 2017 and released in 2.10), so it no longer makes sense to micro-optimize that function for performance. Furthermore, when debugging a server's implementation, tracing the full reply (both names and descriptions) is useful, not to mention that upcoming patches adding 'qemu-nbd --list' will want to collect that data. And when you consider that a server can send an export name up to the NBD protocol length limit of 4k; but our current NBD_MAX_NAME_SIZE is only 256, we can't trace all valid server names without more storage, but 4k is large enough that the heap is better than the stack for long names. Thus, I'm changing the division of labor, with nbd_receive_list() now always malloc'ing a result on success (the malloc is bounded by the fact that we reject servers with a reply length larger than 32M), and moving the comparison to 'wantname' to the caller. There is a minor change in behavior where a server with 0 exports (an immediate NBD_REP_ACK reply) is now no longer distinguished from a server without LIST support (NBD_REP_ERR_UNSUP); this information could be preserved with a complication to the calling contract to provide a bit more information, but I didn't see the point. After all, the worst that can happen if our guess at a match is wrong is that the caller will get a cryptic disconnect when NBD_OPT_EXPORT_NAME fails (which is no different from what would happen if we had not tried LIST), while treating an empty list as immediate failure would prevent connecting to really old servers that really did lack LIST. Besides, NBD servers with 0 exports are rare (qemu can do it when using QMP nbd-server-start without nbd-server-add - but qemu understands NBD_OPT_GO and thus won't tickle this change in behavior). Fix the spelling of foundExport to match coding standards while in the area. Signed-off-by: Eric Blake <eblake@redhat.com> Reviewed-by: Richard W.M. Jones <rjones@redhat.com> Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Message-Id: <20190117193658.16413-9-eblake@redhat.com>
* nbd/client: Trace all server option error messagesEric Blake2019-01-051-0/+1
| | | | | | | | | | | | Not all servers send free-form text alongside option error replies, but for servers that do (such as qemu), we pass the server's message as a hint alongside our own error reporting. However, it would also be useful to trace such server messages, since we can't guarantee how the hint may be consumed. Signed-off-by: Eric Blake <eblake@redhat.com> Message-Id: <20181218225714.284495-3-eblake@redhat.com> Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
* nbd/server: implement dirty bitmap exportVladimir Sementsov-Ogievskiy2018-06-211-0/+1
| | | | | | | | | | | | | | | | Handle a new NBD meta namespace: "qemu", and corresponding queries: "qemu:dirty-bitmap:<export bitmap name>". With the new metadata context negotiated, BLOCK_STATUS query will reply with dirty-bitmap data, converted to extents. The new public function nbd_export_bitmap selects which bitmap to export. For now, only one bitmap may be exported. Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Message-Id: <20180609151758.17343-5-vsementsov@virtuozzo.com> Reviewed-by: Eric Blake <eblake@redhat.com> [eblake: wording tweaks, minor cleanups, additional tracing] Signed-off-by: Eric Blake <eblake@redhat.com>
* nbd: trace meta context negotiationEric Blake2018-04-021-0/+6
| | | | | | | | | | Having a more detailed log of the interaction between client and server is invaluable in debugging how meta context negotiation actually works. Signed-off-by: Eric Blake <eblake@redhat.com> Message-Id: <20180330130950.1931229-1-eblake@redhat.com> Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
* nbd/client: fix error messages in nbd_handle_reply_errVladimir Sementsov-Ogievskiy2018-03-011-4/+4
| | | | | | | | | | | | | | 1. NBD_REP_ERR_INVALID is not only about length, so, make message more general 2. hex format is not very good: it's hard to read something like "option a (set meta context)", so switch to dec. Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Message-Id: <1518702707-7077-6-git-send-email-vsementsov@virtuozzo.com> [eblake: expand scope of patch: ALL uses of nbd_opt_lookup and nbd_rep_lookup are now decimal] Signed-off-by: Eric Blake <eblake@redhat.com>
* nbd/server: Implement sparse reads atop structured replyEric Blake2018-01-081-0/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | The reason that NBD added structured reply in the first place was to allow for efficient reads of sparse files, by allowing the reply to include chunks to quickly communicate holes to the client without sending lots of zeroes over the wire. Time to implement this in the server; our client can already read such data. We can only skip holes insofar as the block layer can query them; and only if the client is okay with a fragmented request (if a client requests NBD_CMD_FLAG_DF and the entire read is a hole, we could technically return a single NBD_REPLY_TYPE_OFFSET_HOLE, but that's a fringe case not worth catering to here). Sadly, the control flow is a bit wonkier than I would have preferred, but it was minimally invasive to have a split in the action between a fragmented read (handled directly where we recognize NBD_CMD_READ with the right conditions, and sending multiple chunks) vs. a single read (handled at the end of nbd_trip, for both simple and structured replies, when we know there is only one thing being read). Likewise, I didn't make any effort to optimize the final chunk of a fragmented read to set the NBD_REPLY_FLAG_DONE, but unconditionally send that as a separate NBD_REPLY_TYPE_NONE. Signed-off-by: Eric Blake <eblake@redhat.com> Message-Id: <20171107030912.23930-2-eblake@redhat.com> Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
* nbd/server: Fix structured read of length 0Eric Blake2017-11-091-0/+1
| | | | | | | | | | | | | | | | | | | | | | | | | The NBD spec was recently clarified to state that a read of length 0 should not be attempted by a compliant client; but that a server must still handle it correctly in an unspecified manner (that is, either a successful no-op or an error reply, but not a crash) [1]. However, it also implies that NBD_REPLY_TYPE_OFFSET_DATA must have a non-zero payload length, but our existing code was replying with a chunk that a picky client could reject as invalid because it was missing a payload (our own client implementation was recently patched to be that picky, after first fixing it to not send 0-length requests). We are already doing successful no-ops for 0-length writes and for non-structured reads; so for consistency, we want structured reply reads to also be a no-op. The easiest way to do this is to return a NBD_REPLY_TYPE_NONE chunk; this is best done via a new helper function (especially since future patches for other structured replies may benefit from using the same helper). [1] https://github.com/NetworkBlockDevice/nbd/commit/ee926037 Signed-off-by: Eric Blake <eblake@redhat.com> Message-Id: <20171108215703.9295-8-eblake@redhat.com> Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
* nbd/client: Nicer trace of structured replyEric Blake2017-11-091-1/+1
| | | | | | | | | It's useful to know which structured reply chunk is being processed. Missed in commit d2febedb. Signed-off-by: Eric Blake <eblake@redhat.com> Message-Id: <20171108215703.9295-4-eblake@redhat.com> Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
* nbd/client: prepare nbd_receive_reply for structured replyVladimir Sementsov-Ogievskiy2017-10-301-1/+2
| | | | | | | | | | | | In following patch nbd_receive_reply will be used both for simple and structured reply header receiving. NBDReply is altered into union of simple reply header and structured reply chunk header, simple error translation moved to block/nbd-client to be consistent with further structured reply error translation. Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Signed-off-by: Eric Blake <eblake@redhat.com> Message-Id: <20171027104037.8319-11-eblake@redhat.com>
* nbd/client: refactor nbd_receive_starttlsVladimir Sementsov-Ogievskiy2017-10-301-3/+1Star
| | | | | | | | | Split out nbd_request_simple_option to be reused for structured reply option. Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Signed-off-by: Eric Blake <eblake@redhat.com> Message-Id: <20171027104037.8319-10-eblake@redhat.com>
* nbd/server: Include human-readable message in structured errorsEric Blake2017-10-301-1/+1
| | | | | | | | | | The NBD spec permits including a human-readable error string if structured replies are in force, so we might as well send the client the message that we logged on any error. Signed-off-by: Eric Blake <eblake@redhat.com> Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Message-Id: <20171027104037.8319-9-eblake@redhat.com>
* nbd: Minimal structured read for serverVladimir Sementsov-Ogievskiy2017-10-301-0/+2
| | | | | | | | | | | | Minimal implementation of structured read: one structured reply chunk, no segmentation. Minimal structured error implementation: no text message. Support DF flag, but just ignore it, as there is no segmentation any way. Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Signed-off-by: Eric Blake <eblake@redhat.com> Message-Id: <20171027104037.8319-8-eblake@redhat.com>
* nbd: Move nbd_errno_to_system_errno() to public headerEric Blake2017-10-301-1/+3
| | | | | | | | | | This is needed in preparation for structured reply handling, as we will be performing the translation from NBD error to system errno value higher in the stack at block/nbd-client.c. Signed-off-by: Eric Blake <eblake@redhat.com> Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Message-Id: <20171027104037.8319-3-eblake@redhat.com>
* nbd: Include error names in trace messagesEric Blake2017-10-301-2/+2
| | | | | | | | | | | | | | NBD errors were originally sent over the wire based on Linux errno values; but not all the world is Linux, and not all platforms share the same values. Since a number isn't very easy to decipher on all platforms, update the trace messages to include the name of NBD errors being sent/received over the wire. Tweak the trace messages to be at the point where we are using the NBD error, not the translation to the host errno values. Signed-off-by: Eric Blake <eblake@redhat.com> Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Message-Id: <20171027104037.8319-2-eblake@redhat.com>
* nbd/server: structurize simple reply header sendingVladimir Sementsov-Ogievskiy2017-10-121-1/+0Star
| | | | | | | | | | | Use packed structure instead of pointer arithmetics. Also, merge two redundant traces into one. Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Message-Id: <20171012095319.136610-5-vsementsov@virtuozzo.com> [eblake: tweak and mention impact on traces, fix errp usage] Signed-off-by: Eric Blake <eblake@redhat.com>
* nbd: rename some simple-request related objects to be _simple_Vladimir Sementsov-Ogievskiy2017-10-121-1/+1
| | | | | | | | | | To be consistent when their _structured_ analogs will be introduced. Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Reviewed-by: Eric Blake <eblake@redhat.com> Message-Id: <20171012095319.136610-4-vsementsov@virtuozzo.com> [eblake: also tweak trace message contents] Signed-off-by: Eric Blake <eblake@redhat.com>
* trace-events: fix code style: print 0x before hex numbersVladimir Sementsov-Ogievskiy2017-08-011-9/+9
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The only exception are groups of numers separated by symbols '.', ' ', ':', '/', like 'ab.09.7d'. This patch is made by the following: > find . -name trace-events | xargs python script.py where script.py is the following python script: ========================= #!/usr/bin/env python import sys import re import fileinput rhex = '%[-+ *.0-9]*(?:[hljztL]|ll|hh)?(?:x|X|"\s*PRI[xX][^"]*"?)' rgroup = re.compile('((?:' + rhex + '[.:/ ])+' + rhex + ')') rbad = re.compile('(?<!0x)' + rhex) files = sys.argv[1:] for fname in files: for line in fileinput.input(fname, inplace=True): arr = re.split(rgroup, line) for i in range(0, len(arr), 2): arr[i] = re.sub(rbad, '0x\g<0>', arr[i]) sys.stdout.write(''.join(arr)) ========================= Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com> Acked-by: Cornelia Huck <cohuck@redhat.com> Message-id: 20170731160135.12101-5-vsementsov@virtuozzo.com Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
* nbd: Trace client command being sentEric Blake2017-07-181-1/+1
| | | | | | | | | Make the client trace slightly more legible by including the name of the command being sent. Signed-off-by: Eric Blake <eblake@redhat.com> Reviewed-by: John Snow <jsnow@redhat.com> Message-Id: <20170717192635.17880-2-eblake@redhat.com>
* nbd: Implement NBD_INFO_BLOCK_SIZE on clientEric Blake2017-07-141-0/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | The upstream NBD Protocol has defined a new extension to allow the server to advertise block sizes to the client, as well as a way for the client to inform the server whether it intends to obey block sizes. When using the block layer as the client, we will obey block sizes; but when used as 'qemu-nbd -c' to hand off to the kernel nbd module as the client, we are still waiting for the kernel to implement a way for us to learn if it will honor block sizes (perhaps by an addition to sysfs, rather than an ioctl), as well as any way to tell the kernel what additional block sizes to obey (NBD_SET_BLKSIZE appears to be accurate for the minimum size, but preferred and maximum sizes would probably be new ioctl()s), so until then, we need to make our request for block sizes conditional. When using ioctl(NBD_SET_BLKSIZE) to hand off to the kernel, use the minimum block size as the sector size if it is larger than 512, which also has the nice effect of cooperating with (non-qemu) servers that don't do read-modify-write when exposing a block device with 4k sectors; it might also allow us to visit a file larger than 2T on a 32-bit kernel. Signed-off-by: Eric Blake <eblake@redhat.com> Message-Id: <20170707203049.534-10-eblake@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
* nbd: Implement NBD_INFO_BLOCK_SIZE on serverEric Blake2017-07-141-0/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The upstream NBD Protocol has defined a new extension to allow the server to advertise block sizes to the client, as well as a way for the client to inform the server that it intends to obey block sizes. Thanks to a recent fix (commit df7b97ff), our real minimum transfer size is always 1 (the block layer takes care of read-modify-write on our behalf), but we're still more efficient if we advertise 512 when the client supports it, as follows: - OPT_INFO, but no NBD_INFO_BLOCK_SIZE: advertise 512, then fail with NBD_REP_ERR_BLOCK_SIZE_REQD; client is free to try something else since we don't disconnect - OPT_INFO with NBD_INFO_BLOCK_SIZE: advertise 512 - OPT_GO, but no NBD_INFO_BLOCK_SIZE: advertise 1 - OPT_GO with NBD_INFO_BLOCK_SIZE: advertise 512 We can also advertise the optimum block size (presumably the cluster size, when exporting a qcow2 file), and our absolute maximum transfer size of 32M, to help newer clients avoid EINVAL failures or abrupt disconnects on oversize requests. We do not reject clients for using the older NBD_OPT_EXPORT_NAME; we are no worse off for those clients than we used to be. Signed-off-by: Eric Blake <eblake@redhat.com> Message-Id: <20170707203049.534-9-eblake@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
* nbd: Implement NBD_OPT_GO on clientEric Blake2017-07-141-0/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | NBD_OPT_EXPORT_NAME is lousy: per the NBD protocol, any failure requires the server to close the connection rather than report an error to us. Therefore, upstream NBD recently added NBD_OPT_GO as the improved version of the option that does what we want [1]: it reports sane errors on failures, and on success provides at least as much info as NBD_OPT_EXPORT_NAME. [1] https://github.com/NetworkBlockDevice/nbd/blob/extension-info/doc/proto.md This is a first cut at use of the information types. Note that we do not need to use NBD_OPT_INFO, and that use of NBD_OPT_GO means we no longer have to use NBD_OPT_LIST to learn whether a server requires TLS (this requires servers that gracefully handle unknown NBD_OPT, many servers prior to qemu 2.5 were buggy, but I have patched qemu, upstream nbd, and nbdkit in the meantime, in part because of interoperability testing with this patch). We still fall back to NBD_OPT_LIST when NBD_OPT_GO is not supported on the server, as it is still one last chance for a nicer error message. Later patches will use further info, like NBD_INFO_BLOCK_SIZE. Signed-off-by: Eric Blake <eblake@redhat.com> Message-Id: <20170707203049.534-8-eblake@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
* nbd: Implement NBD_OPT_GO on serverEric Blake2017-07-141-0/+3
| | | | | | | | | | | | | | | | | | | | | NBD_OPT_EXPORT_NAME is lousy: per the NBD protocol, any failure requires us to close the connection rather than report an error. Therefore, upstream NBD recently added NBD_OPT_GO as the improved version of the option that does what we want [1], along with NBD_OPT_INFO that returns the same information but does not transition to transmission phase. [1] https://github.com/NetworkBlockDevice/nbd/blob/extension-info/doc/proto.md This is a first cut at the information types, and only passes the same information already available through NBD_OPT_LIST and NBD_OPT_EXPORT_NAME; items like NBD_INFO_BLOCK_SIZE (and thus any use of NBD_REP_ERR_BLOCK_SIZE_REQD) are intentionally left for later patches. Signed-off-by: Eric Blake <eblake@redhat.com> Message-Id: <20170707203049.534-7-eblake@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
* nbd: Simplify trace of client flags in negotiationEric Blake2017-07-141-3/+1Star
| | | | | | | | | Simplify the tracing of client flags in the server, and return -EINVAL instead of -EIO if we successfully read but don't like those flags. Signed-off-by: Eric Blake <eblake@redhat.com> Message-Id: <20170707203049.534-5-eblake@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
* nbd: Expose and debug more NBD constantsEric Blake2017-07-141-6/+6
| | | | | | | | | | | The NBD protocol has several constants defined in various extensions that we are about to implement. Expose them to the code, along with an easy way to map various constants to strings during diagnostic messages. Signed-off-by: Eric Blake <eblake@redhat.com> Message-Id: <20170707203049.534-4-eblake@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
* nbd: Don't bother tracing an NBD_OPT_ABORT response failureEric Blake2017-07-141-1/+0Star
| | | | | | | | | We really don't care if our spec-compliant reply to NBD_OPT_ABORT was received, so shave off some lines of code by not even tracing it. Signed-off-by: Eric Blake <eblake@redhat.com> Message-Id: <20170707203049.534-3-eblake@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
* nbd: use generic trace subsystem instead of TRACE macroVladimir Sementsov-Ogievskiy2017-07-101-0/+56
Let NBD use the trace mechanisms already present in qemu. Now you can use the -trace optino of qemu, or the -T/--trace option of qemu-img, qemu-io, and qemu-nbd, to select nbd traces. For qemu, the QMP commands trace-event-{get,set}-state can also toggle tracing on the fly. Example: qemu-nbd --trace 'nbd_*' <image file> # enables all nbd traces Recompilation with CFLAGS=-DDEBUG_NBD is no more needed, furthermore, DEBUG_NBD macro is removed from the code. Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Message-Id: <20170707152918.23086-11-vsementsov@virtuozzo.com> [eblake: minor tweaks to a couple of traces] Signed-off-by: Eric Blake <eblake@redhat.com>
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