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2017-10-12block/nbd-client: refactor nbd_co_receive_replyVladimir Sementsov-Ogievskiy
Pass handle parameter directly, as the whole request isn't needed. Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Reviewed-by: Eric Blake <eblake@redhat.com> Message-Id: <20171012095319.136610-3-vsementsov@virtuozzo.com> Signed-off-by: Eric Blake <eblake@redhat.com>
2017-10-12block/nbd-client: assert qiov len once in nbd_co_requestVladimir Sementsov-Ogievskiy
Also improve the assertion: check that qiov is NULL for other commands than CMD_READ and CMD_WRITE. Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Reviewed-by: Eric Blake <eblake@redhat.com> Message-Id: <20171012095319.136610-2-vsementsov@virtuozzo.com> Signed-off-by: Eric Blake <eblake@redhat.com>
2017-09-25block/nbd-client: nbd_co_send_request: fix return codeVladimir Sementsov-Ogievskiy
It's incorrect to return success rc >= 0 if we skip qio_channel_writev_all() call due to s->quit. Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Reviewed-by: Eric Blake <eblake@redhat.com> Message-Id: <20170920124507.18841-4-vsementsov@virtuozzo.com> Signed-off-by: Eric Blake <eblake@redhat.com>
2017-09-25block/nbd-client: simplify check in nbd_co_receive_replyVladimir Sementsov-Ogievskiy
If we are woken up from while() loop in nbd_read_reply_entry handles must be equal. If we are woken up from nbd_recv_coroutines_wake_all s->quit must be true, so we do not need checking handles equality. Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Reviewed-by: Eric Blake <eblake@redhat.com> Message-Id: <20170920124507.18841-3-vsementsov@virtuozzo.com> Signed-off-by: Eric Blake <eblake@redhat.com>
2017-09-25block/nbd-client: refactor nbd_co_receive_replyVladimir Sementsov-Ogievskiy
"NBDReply *reply" parameter of nbd_co_receive_reply is used only to pass return value for nbd_co_request (reply.error). Remove it and use function return value instead. Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Reviewed-by: Eric Blake <eblake@redhat.com> Message-Id: <20170920124507.18841-2-vsementsov@virtuozzo.com> Signed-off-by: Eric Blake <eblake@redhat.com>
2017-09-25nbd-client: Use correct macro parenthesizationEric Blake
If 'bs' is a complex expression, we were only casting the front half rather than the full expression. Luckily, none of the callers were passing bad arguments, but it's better to be robust up front. Signed-off-by: Eric Blake <eblake@redhat.com> Message-Id: <20170918214649.17550-1-eblake@redhat.com> Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org> Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
2017-09-06nbd: Use new qio_channel_*_all() functionsEric Blake
Rather than open-coding our own read/write-all functions, we can make use of the recently-added qio code. It slightly changes the error message in one of the iotests. Signed-off-by: Eric Blake <eblake@redhat.com> Message-Id: <20170905191114.5959-4-eblake@redhat.com> Reviewed-by: Daniel P. Berrange <berrange@redhat.com>
2017-08-30block/nbd-client: refactor request send/receiveVladimir Sementsov-Ogievskiy
Add nbd_co_request, to remove code duplications in nbd_client_co_{pwrite,pread,...} functions. Also this is needed for further refactoring. Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Message-Id: <20170804151440.320927-8-vsementsov@virtuozzo.com> [eblake: make nbd_co_request a wrapper, rather than merging two existing functions] Signed-off-by: Eric Blake <eblake@redhat.com>
2017-08-30block/nbd-client: rename nbd_recv_coroutines_enter_allVladimir Sementsov-Ogievskiy
Rename nbd_recv_coroutines_enter_all to nbd_recv_coroutines_wake_all, as it most probably just adds all recv coroutines into co_queue_wakeup, rather than directly enter them. Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Message-Id: <20170804151440.320927-9-vsementsov@virtuozzo.com> [eblake: tweak commit message] Signed-off-by: Eric Blake <eblake@redhat.com>
2017-08-30block/nbd-client: get rid of ssize_tVladimir Sementsov-Ogievskiy
Use int variable for nbd_co_send_request return value (as nbd_co_send_request returns int). Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Message-Id: <20170804151440.320927-6-vsementsov@virtuozzo.com> Signed-off-by: Eric Blake <eblake@redhat.com>
2017-08-30nbd-client: avoid read_reply_co entry if send failedStefan Hajnoczi
The following segfault is encountered if the NBD server closes the UNIX domain socket immediately after negotiation: Program terminated with signal SIGSEGV, Segmentation fault. #0 aio_co_schedule (ctx=0x0, co=0xd3c0ff2ef0) at util/async.c:441 441 QSLIST_INSERT_HEAD_ATOMIC(&ctx->scheduled_coroutines, (gdb) bt #0 0x000000d3c01a50f8 in aio_co_schedule (ctx=0x0, co=0xd3c0ff2ef0) at util/async.c:441 #1 0x000000d3c012fa90 in nbd_coroutine_end (bs=bs@entry=0xd3c0fec650, request=<optimized out>) at block/nbd-client.c:207 #2 0x000000d3c012fb58 in nbd_client_co_preadv (bs=0xd3c0fec650, offset=0, bytes=<optimized out>, qiov=0x7ffc10a91b20, flags=0) at block/nbd-client.c:237 #3 0x000000d3c0128e63 in bdrv_driver_preadv (bs=bs@entry=0xd3c0fec650, offset=offset@entry=0, bytes=bytes@entry=512, qiov=qiov@entry=0x7ffc10a91b20, flags=0) at block/io.c:836 #4 0x000000d3c012c3e0 in bdrv_aligned_preadv (child=child@entry=0xd3c0ff51d0, req=req@entry=0x7f31885d6e90, offset=offset@entry=0, bytes=bytes@entry=512, align=align@entry=1, qiov=qiov@entry=0x7ffc10a91b20, f +lags=0) at block/io.c:1086 #5 0x000000d3c012c6b8 in bdrv_co_preadv (child=0xd3c0ff51d0, offset=offset@entry=0, bytes=bytes@entry=512, qiov=qiov@entry=0x7ffc10a91b20, flags=flags@entry=0) at block/io.c:1182 #6 0x000000d3c011cc17 in blk_co_preadv (blk=0xd3c0ff4f80, offset=0, bytes=512, qiov=0x7ffc10a91b20, flags=0) at block/block-backend.c:1032 #7 0x000000d3c011ccec in blk_read_entry (opaque=0x7ffc10a91b40) at block/block-backend.c:1079 #8 0x000000d3c01bbb96 in coroutine_trampoline (i0=<optimized out>, i1=<optimized out>) at util/coroutine-ucontext.c:79 #9 0x00007f3196cb8600 in __start_context () at /lib64/libc.so.6 The problem is that nbd_client_init() uses nbd_client_attach_aio_context() -> aio_co_schedule(new_context, client->read_reply_co). Execution of read_reply_co is deferred to a BH which doesn't run until later. In the mean time blk_co_preadv() can be called and nbd_coroutine_end() calls aio_wake() on read_reply_co. At this point in time read_reply_co's ctx isn't set because it has never been entered yet. This patch simplifies the nbd_co_send_request() -> nbd_co_receive_reply() -> nbd_coroutine_end() lifecycle to just nbd_co_send_request() -> nbd_co_receive_reply(). The request is "ended" if an error occurs at any point. Callers no longer have to invoke nbd_coroutine_end(). This cleanup also eliminates the segfault because we don't call aio_co_schedule() to wake up s->read_reply_co if sending the request failed. It is only necessary to wake up s->read_reply_co if a reply was received. Note this only happens with UNIX domain sockets on Linux. It doesn't seem possible to reproduce this with TCP sockets. Suggested-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com> Message-Id: <20170829122745.14309-2-stefanha@redhat.com> Signed-off-by: Eric Blake <eblake@redhat.com>
2017-08-23nbd-client: avoid spurious qio_channel_yield() re-entryStefan Hajnoczi
The following scenario leads to an assertion failure in qio_channel_yield(): 1. Request coroutine calls qio_channel_yield() successfully when sending would block on the socket. It is now yielded. 2. nbd_read_reply_entry() calls nbd_recv_coroutines_enter_all() because nbd_receive_reply() failed. 3. Request coroutine is entered and returns from qio_channel_yield(). Note that the socket fd handler has not fired yet so ioc->write_coroutine is still set. 4. Request coroutine attempts to send the request body with nbd_rwv() but the socket would still block. qio_channel_yield() is called again and assert(!ioc->write_coroutine) is hit. The problem is that nbd_read_reply_entry() does not distinguish between request coroutines that are waiting to receive a reply and those that are not. This patch adds a per-request bool receiving flag so nbd_read_reply_entry() can avoid spurious aio_wake() calls. Reported-by: Dr. David Alan Gilbert <dgilbert@redhat.com> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com> Message-Id: <20170822125113.5025-1-stefanha@redhat.com> Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Tested-by: Eric Blake <eblake@redhat.com> Reviewed-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Eric Blake <eblake@redhat.com>
2017-08-23fix build failure in nbd_read_reply_entry()Igor Mammedov
travis builds fail at HEAD at rc3 master with block/nbd-client.c: In function ‘nbd_read_reply_entry’: block/nbd-client.c:110:8: error: ‘ret’ may be used uninitialized in this function [-Werror=uninitialized] fix it by initializing 'ret' to 0 Signed-off-by: Igor Mammedov <imammedo@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
2017-08-15nbd-client: Fix regression when server sends garbageEric Blake
When we switched NBD to use coroutines for qemu 2.9 (in particular, commit a12a712a), we introduced a regression: if a server sends us garbage (such as a corrupted magic number), we quit the read loop but do not stop sending further queued commands, resulting in the client hanging when it never reads the response to those additional commands. In qemu 2.8, we properly detected that the server is no longer reliable, and cancelled all existing pending commands with EIO, then tore down the socket so that all further command attempts get EPIPE. Restore the proper behavior of quitting (almost) all communication with a broken server: Once we know we are out of sync or otherwise can't trust the server, we must assume that any further incoming data is unreliable and therefore end all pending commands with EIO, and quit trying to send any further commands. As an exception, we still (try to) send NBD_CMD_DISC to let the server know we are going away (in part, because it is easier to do that than to further refactor nbd_teardown_connection, and in part because it is the only command where we do not have to wait for a reply). Based on a patch by Vladimir Sementsov-Ogievskiy. A malicious server can be created with the following hack, followed by setting NBD_SERVER_DEBUG to a non-zero value in the environment when running qemu-nbd: | --- a/nbd/server.c | +++ b/nbd/server.c | @@ -919,6 +919,17 @@ static int nbd_send_reply(QIOChannel *ioc, NBDReply *reply, Error **errp) | stl_be_p(buf + 4, reply->error); | stq_be_p(buf + 8, reply->handle); | | + static int debug; | + static int count; | + if (!count++) { | + const char *str = getenv("NBD_SERVER_DEBUG"); | + if (str) { | + debug = atoi(str); | + } | + } | + if (debug && !(count % debug)) { | + buf[0] = 0; | + } | return nbd_write(ioc, buf, sizeof(buf), errp); | } Reported-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Signed-off-by: Eric Blake <eblake@redhat.com> Message-Id: <20170814213426.24681-1-eblake@redhat.com> Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
2017-07-14nbd: Implement NBD_INFO_BLOCK_SIZE on clientEric Blake
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>
2017-07-14nbd: Create struct for tracking export infoEric Blake
The NBD Protocol is introducing some additional information about exports, such as minimum request size and alignment, as well as an advertised maximum request size. It will be easier to feed this information back to the block layer if we gather all the information into a struct, rather than adding yet more pointer parameters during negotiation. Signed-off-by: Eric Blake <eblake@redhat.com> Message-Id: <20170707203049.534-2-eblake@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2017-07-04nbd: fix NBD over TLSPaolo Bonzini
When attaching the NBD QIOChannel to an AioContext, the TLS channel should be used, not the underlying socket channel. This is because, trivially, the TLS channel will be the one that we read/write to and thus the one that will get the qio_channel_yield() call. Fixes: ff82911cd3f69f028f2537825c9720ff78bc3f19 Cc: qemu-stable@nongnu.org Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com> Reviewed-by: Daniel P. Berrange <berrange@redhat.com> Tested-by: Daniel P. Berrange <berrange@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2017-06-26block: change variable names in BlockDriverStateManos Pitsidianakis
Change the 'int count' parameter in *pwrite_zeros, *pdiscard related functions (and some others) to 'int bytes', as they both refer to bytes. This helps with code legibility. Signed-off-by: Manos Pitsidianakis <el13635@mail.ntua.gr> Message-id: 20170609101808.13506-1-el13635@mail.ntua.gr Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com> Signed-off-by: Max Reitz <mreitz@redhat.com>
2017-06-15nbd: rename read_sync and friendsVladimir Sementsov-Ogievskiy
Rename nbd_wr_syncv -> nbd_rwv read_sync -> nbd_read read_sync_eof -> nbd_read_eof write_sync -> nbd_write drop_sync -> nbd_drop 1. nbd_ prefix read_sync and write_sync are already shared, so it is good to have a namespace prefix. drop_sync will be shared, and read_sync_eof is related to read_sync, so let's rename them all. 2. _sync suffix _sync is related to the fact that nbd_wr_syncv doesn't return if a write to socket returns EAGAIN. The first implementation of nbd_wr_syncv (was wr_sync in 7a5ca8648b) just loops while getting EAGAIN, the current implementation yields in this case. Why we want to get rid of it: - it is normal for r/w functions to be synchronous, so having an additional suffix for it looks redundant (contrariwise, we have _aio suffix for async functions) - _sync suffix in block layer is used when function does flush (so using it for other thing is confusing a bit) - keep function names short after adding nbd_ prefix 3. for nbd_wr_syncv let's use more common notation 'rw' Reviewed-by: Eric Blake <eblake@redhat.com> Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Message-Id: <20170602150150.258222-2-vsementsov@virtuozzo.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2017-06-07nbd: make it thread-safe, fix qcow2 over nbdPaolo Bonzini
NBD is not thread safe, because it accesses s->in_flight without a CoMutex. Fixing this will be required for multiqueue. CoQueue doesn't have spurious wakeups but, when another coroutine can run between qemu_co_queue_next's wakeup and qemu_co_queue_wait's re-locking of the mutex, the wait condition can become false and a loop is necessary. In fact, it turns out that the loop is necessary even without this multi-threaded scenario. A particular sequence of coroutine wakeups is happening ~80% of the time when starting a guest with qcow2 image served over NBD (i.e. qemu-nbd --format=raw, and QEMU's -drive option has -format=qcow2). This patch fixes that issue too. Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2017-06-06nbd/client.c: use errp instead of LOGVladimir Sementsov-Ogievskiy
Move to modern errp scheme from just LOGging errors. Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Message-Id: <20170526110913.89098-1-vsementsov@virtuozzo.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2017-06-06nbd: add errp parameter to nbd_wr_syncv()Vladimir Sementsov-Ogievskiy
Will be used in following patch to provide actual error message in some cases. Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Message-Id: <20170516094533.6160-4-vsementsov@virtuozzo.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2017-03-27nbd-client: fix handling of hungup connectionsPaolo Bonzini
After the switch to reading replies in a coroutine, nothing is reentering pending receive coroutines if the connection hangs. Move nbd_recv_coroutines_enter_all to the reply read coroutine, which is the place where hangups are detected. nbd_teardown_connection can simply wait for the reply read coroutine to detect the hangup and clean up after itself. This wouldn't be enough though because nbd_receive_reply returns 0 (rather than -EPIPE or similar) when reading from a hung connection. Fix the return value check in nbd_read_reply_entry. This fixes qemu-iotests 083. Reported-by: Max Reitz <mreitz@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Message-id: 20170314111157.14464-1-pbonzini@redhat.com Reviewed-by: Max Reitz <mreitz@redhat.com> Signed-off-by: Max Reitz <mreitz@redhat.com>
2017-02-21coroutine-lock: add mutex argument to CoQueue APIsPaolo Bonzini
All that CoQueue needs in order to become thread-safe is help from an external mutex. Add this to the API. Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Reviewed-by: Fam Zheng <famz@redhat.com> Message-id: 20170213181244.16297-6-pbonzini@redhat.com Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2017-02-21nbd: convert to use qio_channel_yieldPaolo Bonzini
In the client, read the reply headers from a coroutine, switching the read side between the "read header" coroutine and the I/O coroutine that reads the body of the reply. In the server, if the server can read more requests it will create a new "read request" coroutine as soon as a request has been read. Otherwise, the new coroutine is created in nbd_request_put. Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Reviewed-by: Fam Zheng <famz@redhat.com> Reviewed-by: Daniel P. Berrange <berrange@redhat.com> Message-id: 20170213135235.12274-8-pbonzini@redhat.com Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2017-01-03aio: add AioPollFn and io_poll() interfaceStefan Hajnoczi
The new AioPollFn io_poll() argument to aio_set_fd_handler() and aio_set_event_handler() is used in the next patch. Keep this code change separate due to the number of files it touches. Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com> Reviewed-by: Paolo Bonzini <pbonzini@redhat.com> Message-id: 20161201192652.9509-3-stefanha@redhat.com Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2016-11-22nbd: Allow unmap and fua during write zeroesEric Blake
Commit fa778fff wired up support to send the NBD_CMD_WRITE_ZEROES, but forgot to inform the block layer that FUA unmapping of zeroes is supported. Without BDRV_REQ_MAY_UNMAP listed as a supported flag, the block layer will always insist on the NBD layer passing NBD_CMD_FLAG_NO_HOLE, resulting in the server always allocating things even when it was desired to let the server punch holes. Similarly, failing to set BDRV_REQ_FUA means that the client may send unnecessary NBD_CMD_FLUSH when it could have instead used the NBD_CMD_FLAG_FUA bit. CC: qemu-stable@nongnu.org Signed-off-by: Eric Blake <eblake@redhat.com> Message-Id: <1479413642-22463-2-git-send-email-eblake@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2016-11-02nbd: Implement NBD_CMD_WRITE_ZEROES on clientEric Blake
Upstream NBD protocol recently added the ability to efficiently write zeroes without having to send the zeroes over the wire, along with a flag to control whether the client wants a hole. The generic block code takes care of falling back to the obvious write of lots of zeroes if we return -ENOTSUP because the server does not have WRITE_ZEROES. Ideally, since NBD_CMD_WRITE_ZEROES does not involve any data over the wire, we want to support transactions that are much larger than the normal 32M limit imposed on NBD_CMD_WRITE. But the server may still have a limit smaller than UINT_MAX, so until experimental NBD protocol additions for advertising various command sizes is finalized (see [1], [2]), for now we just stick to the same limits as normal writes. [1] https://github.com/yoe/nbd/blob/extension-info/doc/proto.md [2] https://sourceforge.net/p/nbd/mailman/message/35081223/ Signed-off-by: Eric Blake <eblake@redhat.com> Message-Id: <1476469998-28592-17-git-send-email-eblake@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2016-11-02nbd: Rename struct nbd_request and nbd_replyEric Blake
Our coding convention prefers CamelCase names, and we already have other existing structs with NBDFoo naming. Let's be consistent, before later patches add even more structs. Signed-off-by: Eric Blake <eblake@redhat.com> Message-Id: <1476469998-28592-6-git-send-email-eblake@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2016-11-02nbd: Rename NbdClientSession to NBDClientSessionEric Blake
It's better to use consistent capitalization of the namespace used for NBD functions; we have more instances of NBD* than Nbd*. Signed-off-by: Eric Blake <eblake@redhat.com> Message-Id: <1476469998-28592-5-git-send-email-eblake@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2016-11-02nbd: Treat flags vs. command type as separate fieldsEric Blake
Current upstream NBD documents that requests have a 16-bit flags, followed by a 16-bit type integer; although older versions mentioned only a 32-bit field with masking to find flags. Since the protocol is in network order (big-endian over the wire), the ABI is unchanged; but dealing with the flags as a separate field rather than masking will make it easier to add support for upcoming NBD extensions that increase the number of both flags and commands. Improve some comments in nbd.h based on the current upstream NBD protocol (https://github.com/yoe/nbd/blob/master/doc/proto.md), and touch some nearby code to keep checkpatch.pl happy. Signed-off-by: Eric Blake <eblake@redhat.com> Message-Id: <1476469998-28592-3-git-send-email-eblake@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2016-11-01nbd: Use CoQueue for free_sema instead of CoMutexChanglong Xie
NBD is using the CoMutex in a way that wasn't anticipated. For example, if there are N(N=26, MAX_NBD_REQUESTS=16) nbd write requests, so we will invoke nbd_client_co_pwritev N times. ---------------------------------------------------------------------------------------- time request Actions 1 1 in_flight=1, Coroutine=C1 2 2 in_flight=2, Coroutine=C2 ... 15 15 in_flight=15, Coroutine=C15 16 16 in_flight=16, Coroutine=C16, free_sema->holder=C16, mutex->locked=true 17 17 in_flight=16, Coroutine=C17, queue C17 into free_sema->queue 18 18 in_flight=16, Coroutine=C18, queue C18 into free_sema->queue ... 26 N in_flight=16, Coroutine=C26, queue C26 into free_sema->queue ---------------------------------------------------------------------------------------- Once nbd client recieves request No.16' reply, we will re-enter C16. It's ok, because it's equal to 'free_sema->holder'. ---------------------------------------------------------------------------------------- time request Actions 27 16 in_flight=15, Coroutine=C16, free_sema->holder=C16, mutex->locked=false ---------------------------------------------------------------------------------------- Then nbd_coroutine_end invokes qemu_co_mutex_unlock what will pop coroutines from free_sema->queue's head and enter C17. More free_sema->holder is C17 now. ---------------------------------------------------------------------------------------- time request Actions 28 17 in_flight=16, Coroutine=C17, free_sema->holder=C17, mutex->locked=true ---------------------------------------------------------------------------------------- In above scenario, we only recieves request No.16' reply. As time goes by, nbd client will almostly recieves replies from requests 1 to 15 rather than request 17 who owns C17. In this case, we will encounter assert "mutex->holder == self" failed since Kevin's commit 0e438cdc "coroutine: Let CoMutex remember who holds it". For example, if nbd client recieves request No.15' reply, qemu will stop unexpectedly: ---------------------------------------------------------------------------------------- time request Actions 29 15(most case) in_flight=15, Coroutine=C15, free_sema->holder=C17, mutex->locked=false ---------------------------------------------------------------------------------------- Per Paolo's suggestion "The simplest fix is to change it to CoQueue, which is like a condition variable", this patch replaces CoMutex with CoQueue. Cc: Wen Congyang <wency@cn.fujitsu.com> Reported-by: zhanghailiang <zhang.zhanghailiang@huawei.com> Suggested-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Changlong Xie <xiecl.fnst@cn.fujitsu.com> Message-Id: <1476267508-19499-1-git-send-email-xiecl.fnst@cn.fujitsu.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2016-07-20nbd: Convert to byte-based interfaceEric Blake
The NBD protocol doesn't have any notion of sectors, so it is a fairly easy conversion to use byte-based read and write. Signed-off-by: Eric Blake <eblake@redhat.com> Acked-by: Paolo Bonzini <pbonzini@redhat.com> Message-id: 1468624988-423-19-git-send-email-eblake@redhat.com Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2016-07-20nbd: Switch .bdrv_co_discard() to byte-basedEric Blake
Another step towards killing off sector-based block APIs. While at it, call directly into nbd-client.c instead of having a pointless trivial wrapper in nbd.c. Signed-off-by: Eric Blake <eblake@redhat.com> Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com> Message-id: 1468624988-423-14-git-send-email-eblake@redhat.com Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2016-07-20nbd: Drop unused offset parameterEric Blake
Now that NBD relies on the block layer to fragment things, we no longer need to track an offset argument for which fragment of a request we are actually servicing. While at it, use true and false instead of 0 and 1 for a bool parameter. Signed-off-by: Eric Blake <eblake@redhat.com> Reviewed-by: Fam Zheng <famz@redhat.com> Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com> Acked-by: Paolo Bonzini <pbonzini@redhat.com> Message-id: 1468607524-19021-6-git-send-email-eblake@redhat.com Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2016-07-20nbd: Rely on block layer to break up large requestsEric Blake
Now that the block layer will honor max_transfer, we can simplify our code to rely on that guarantee. The readv code can call directly into nbd-client, just as the writev code has done since commit 52a4650. Interestingly enough, while qemu-io 'w 0 40m' splits into a 32M and 8M transaction, 'w -z 0 40m' splits into two 16M and an 8M, because the block layer caps the bounce buffer for writing zeroes at 16M. When we later introduce support for NBD_CMD_WRITE_ZEROES, we can get a full 32M zero write (or larger, if the client and server negotiate that write zeroes can use a larger size than ordinary writes). Signed-off-by: Eric Blake <eblake@redhat.com> Reviewed-by: Fam Zheng <famz@redhat.com> Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com> Acked-by: Paolo Bonzini <pbonzini@redhat.com> Message-id: 1468607524-19021-5-git-send-email-eblake@redhat.com Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2016-07-13coroutine: move entry argument to qemu_coroutine_createPaolo Bonzini
In practice the entry argument is always known at creation time, and it is confusing that sometimes qemu_coroutine_enter is used with a non-NULL argument to re-enter a coroutine (this happens in block/sheepdog.c and tests/test-coroutine.c). So pass the opaque value at creation time, for consistency with e.g. aio_bh_new. Mostly done with the following semantic patch: @ entry1 @ expression entry, arg, co; @@ - co = qemu_coroutine_create(entry); + co = qemu_coroutine_create(entry, arg); ... - qemu_coroutine_enter(co, arg); + qemu_coroutine_enter(co); @ entry2 @ expression entry, arg; identifier co; @@ - Coroutine *co = qemu_coroutine_create(entry); + Coroutine *co = qemu_coroutine_create(entry, arg); ... - qemu_coroutine_enter(co, arg); + qemu_coroutine_enter(co); @ entry3 @ expression entry, arg; @@ - qemu_coroutine_enter(qemu_coroutine_create(entry), arg); + qemu_coroutine_enter(qemu_coroutine_create(entry, arg)); @ reentry @ expression co; @@ - qemu_coroutine_enter(co, NULL); + qemu_coroutine_enter(co); except for the aforementioned few places where the semantic patch stumbled (as expected) and for test_co_queue, which would otherwise produce an uninitialized variable warning. Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Reviewed-by: Fam Zheng <famz@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2016-07-05nbd: Allow larger requestsEric Blake
The NBD layer was breaking up request at a limit of 2040 sectors (just under 1M) to cater to old qemu-nbd. But the server limit was raised to 32M in commit 2d8214885 to match the kernel, more than three years ago; and the upstream NBD Protocol is proposing documentation that without any explicit communication to state otherwise, a client should be able to safely assume that a 32M transaction will work. It is time to rely on the larger sizing, and any downstream distro that cares about maximum interoperability to older qemu-nbd servers can just tweak the value of #define NBD_MAX_SECTORS. Signed-off-by: Eric Blake <eblake@redhat.com> Reviewed-by: Kevin Wolf <kwolf@redhat.com> Acked-by: Paolo Bonzini <pbonzini@redhat.com> Cc: qemu-stable@nongnu.org Reviewed-by: Fam Zheng <famz@redhat.com> Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2016-05-12nbd: Simplify client FUA handlingEric Blake
Now that the block layer honors per-bds FUA support, we don't have to duplicate the fallback flush at the NBD layer. The static function nbd_co_writev_flags() is no longer needed, and the driver can just directly use nbd_client_co_writev(). Signed-off-by: Eric Blake <eblake@redhat.com> Reviewed-by: Fam Zheng <famz@redhat.com> Acked-by: Stefan Hajnoczi <stefanha@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2016-05-12block: Make supported_write_flags a per-bds propertyEric Blake
Pre-patch, .supported_write_flags lives at the driver level, which means we are blindly declaring that all block devices using a given driver will either equally support FUA, or that we need a fallback at the block layer. But there are drivers where FUA support is a per-block decision: the NBD block driver is dependent on the remote server advertising NBD_FLAG_SEND_FUA (and has fallback code to duplicate the flush that the block layer would do if NBD had not set .supported_write_flags); and the iscsi block driver is dependent on the mode sense bits advertised by the underlying device (and is currently silently ignoring FUA requests if the underlying device does not support FUA). The fix is to make supported flags as a per-BDS option, set during .bdrv_open(). This patch moves the variable and fixes NBD and iscsi to set it only conditionally; later patches will then further simplify the NBD driver to quit duplicating work done at the block layer, as well as tackle the fact that SCSI does not support FUA semantics on WRITESAME(10/16) but only on WRITE(10/16). Signed-off-by: Eric Blake <eblake@redhat.com> Reviewed-by: Fam Zheng <famz@redhat.com> Acked-by: Stefan Hajnoczi <stefanha@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2016-04-05nbd: don't request FUA on FLUSHEric Blake
The NBD protocol does not clearly document what will happen if a client sends NBD_CMD_FLAG_FUA on NBD_CMD_FLUSH. Historically, both the qemu and upstream NBD servers silently ignored that flag, but that feels a bit risky. Meanwhile, the qemu NBD client unconditionally sends the flag (without even bothering to check whether the caller cares; at least with NBD_CMD_WRITE the client only sends FUA if requested by a higher layer). There is ongoing discussion on the NBD list to fix the protocol documentation to require that the server MUST ignore the flag (unless the kernel folks can better explain what FUA means for a flush), but until those doc improvements land, the current nbd.git master was recently changed to reject the flag with EINVAL (see nbd commit ab22e082), which now makes it impossible for a qemu client to use FLUSH with an upstream NBD server. We should not send FUA with flush unless the upstream protocol documents what it will do, and even then, it should be something that the caller can opt into, rather than being unconditional. Signed-off-by: Eric Blake <eblake@redhat.com> Message-Id: <1459526902-32561-1-git-send-email-eblake@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2016-03-30nbd: Support BDRV_REQ_FUAKevin Wolf
The NBD server already used to send a FUA flag when the writethrough mode was set. This code was a remnant from the times where protocol drivers actually had to implement writethrough modes. Since nowadays the block layer sends flushes in writethrough mode and non-root nodes are always writeback, this was mostly dead code - only mostly because if NBD was configured to be used without a format, we sent _both_ FUA and an explicit flush afterwards, which makes the code not technically dead, but useless overhead. This patch changes the code so that the block layer's FUA flag is recognised and translated into a NBD FUA flag. The additional flush is avoided now. Signed-off-by: Kevin Wolf <kwolf@redhat.com> Reviewed-by: Max Reitz <mreitz@redhat.com>
2016-02-16nbd: enable use of TLS with NBD block driverDaniel P. Berrange
This modifies the NBD driver so that it is possible to request use of TLS. This is done by providing the 'tls-creds' parameter with the ID of a previously created QCryptoTLSCreds object. For example $QEMU -object tls-creds-x509,id=tls0,endpoint=client,\ dir=/home/berrange/security/qemutls \ -drive driver=nbd,host=localhost,port=9000,tls-creds=tls0 The client will drop the connection if the NBD server does not provide TLS. Signed-off-by: Daniel P. Berrange <berrange@redhat.com> Message-Id: <1455129674-17255-15-git-send-email-berrange@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2016-02-16nbd: implement TLS support in the protocol negotiationDaniel P. Berrange
This extends the NBD protocol handling code so that it is capable of negotiating TLS support during the connection setup. This involves requesting the STARTTLS protocol option before any other NBD options. Signed-off-by: Daniel P. Berrange <berrange@redhat.com> Message-Id: <1455129674-17255-14-git-send-email-berrange@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2016-02-16nbd: convert to using I/O channels for actual socket I/ODaniel P. Berrange
Now that all callers are converted to use I/O channels for initial connection setup, it is possible to switch the core NBD protocol handling core over to use QIOChannel APIs for actual sockets I/O. Signed-off-by: Daniel P. Berrange <berrange@redhat.com> Message-Id: <1455129674-17255-7-git-send-email-berrange@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2016-02-16nbd: convert block client to use I/O channels for connection setupDaniel P. Berrange
This converts the NBD block driver client to use the QIOChannelSocket class for initial connection setup. The NbdClientSession struct has two pointers, one to the master QIOChannelSocket providing the raw data channel, and one to a QIOChannel which is the current channel used for I/O. Initially the two point to the same object, but when TLS support is added, they will point to different objects. The qemu-img & qemu-io tools now need to use MODULE_INIT_QOM to ensure the QIOChannel object classes are registered. The qemu-nbd tool already did this. In this initial conversion though, all I/O is still actually done using the raw POSIX sockets APIs. Signed-off-by: Daniel P. Berrange <berrange@redhat.com> Message-Id: <1455129674-17255-4-git-send-email-berrange@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2016-01-20block: Clean up includesPeter Maydell
Clean up includes so that osdep.h is included first and headers which it implies are not included manually. This commit was created with scripts/clean-includes. Signed-off-by: Peter Maydell <peter.maydell@linaro.org> Reviewed-by: Eric Blake <eblake@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2015-10-23aio: Add "is_external" flag for event handlersFam Zheng
All callers pass in false, and the real external ones will switch to true in coming patches. Signed-off-by: Fam Zheng <famz@redhat.com> Reviewed-by: Jeff Cody <jcody@redhat.com> Reviewed-by: Kevin Wolf <kwolf@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2015-03-18nbd: Set block size to BDRV_SECTOR_SIZEMax Reitz
Signed-off-by: Max Reitz <mreitz@redhat.com> Message-Id: <1424887718-10800-13-git-send-email-mreitz@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2015-02-16nbd: fix the co_queue multi-adding bugBin Wu
When we tested the VM migartion between different hosts with NBD devices, we found if we sent a cancel command after the drive_mirror was just started, a coroutine re-enter error would occur. The stack was as follow: (gdb) bt 00) 0x00007fdfc744d885 in raise () from /lib64/libc.so.6 01) 0x00007fdfc744ee61 in abort () from /lib64/libc.so.6 02) 0x00007fdfca467cc5 in qemu_coroutine_enter (co=0x7fdfcaedb400, opaque=0x0) at qemu-coroutine.c:118 03) 0x00007fdfca467f6c in qemu_co_queue_run_restart (co=0x7fdfcaedb400) at qemu-coroutine-lock.c:59 04) 0x00007fdfca467be5 in coroutine_swap (from=0x7fdfcaf3c4e8, to=0x7fdfcaedb400) at qemu-coroutine.c:96 05) 0x00007fdfca467cea in qemu_coroutine_enter (co=0x7fdfcaedb400, opaque=0x0) at qemu-coroutine.c:123 06) 0x00007fdfca467f6c in qemu_co_queue_run_restart (co=0x7fdfcaedbdc0) at qemu-coroutine-lock.c:59 07) 0x00007fdfca467be5 in coroutine_swap (from=0x7fdfcaf3c4e8, to=0x7fdfcaedbdc0) at qemu-coroutine.c:96 08) 0x00007fdfca467cea in qemu_coroutine_enter (co=0x7fdfcaedbdc0, opaque=0x0) at qemu-coroutine.c:123 09) 0x00007fdfca4a1fa4 in nbd_recv_coroutines_enter_all (s=0x7fdfcaef7dd0) at block/nbd-client.c:41 10) 0x00007fdfca4a1ff9 in nbd_teardown_connection (client=0x7fdfcaef7dd0) at block/nbd-client.c:50 11) 0x00007fdfca4a20f0 in nbd_reply_ready (opaque=0x7fdfcaef7dd0) at block/nbd-client.c:92 12) 0x00007fdfca45ed80 in aio_dispatch (ctx=0x7fdfcae15e90) at aio-posix.c:144 13) 0x00007fdfca45ef1b in aio_poll (ctx=0x7fdfcae15e90, blocking=false) at aio-posix.c:222 14) 0x00007fdfca448c34 in aio_ctx_dispatch (source=0x7fdfcae15e90, callback=0x0, user_data=0x0) at async.c:212 15) 0x00007fdfc8f2f69a in g_main_context_dispatch () from /usr/lib64/libglib-2.0.so.0 16) 0x00007fdfca45c391 in glib_pollfds_poll () at main-loop.c:190 17) 0x00007fdfca45c489 in os_host_main_loop_wait (timeout=1483677098) at main-loop.c:235 18) 0x00007fdfca45c57b in main_loop_wait (nonblocking=0) at main-loop.c:484 19) 0x00007fdfca25f403 in main_loop () at vl.c:2249 20) 0x00007fdfca266fc2 in main (argc=42, argv=0x7ffff517d638, envp=0x7ffff517d790) at vl.c:4814 We find the nbd_recv_coroutines_enter_all function (triggered by a cancel command or a network connection breaking down) will enter a coroutine which is waiting for the sending lock. If the lock is still held by another coroutine, the entering coroutine will be added into the co_queue again. Latter, when the lock is released, a coroutine re-enter error will occur. This bug can be fixed simply by delaying the setting of recv_coroutine as suggested by paolo. After applying this patch, we have tested the cancel operation in mirror phase looply for more than 5 hous and everything is fine. Without this patch, a coroutine re-enter error will occur in 5 minutes. Signed-off-by: Bn Wu <wu.wubin@huawei.com> Reviewed-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Message-id: 1423552846-3896-1-git-send-email-wu.wubin@huawei.com Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
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