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2020-10-30nbd: Add 'qemu-nbd -A' to expose allocation depthEric Blake1-5/+21
Allow the server to expose an additional metacontext to be requested by savvy clients. qemu-nbd adds a new option -A to expose the qemu:allocation-depth metacontext through NBD_CMD_BLOCK_STATUS; this can also be set via QMP when using block-export-add. qemu as client is hacked into viewing the key aspects of this new context by abusing the already-experimental x-dirty-bitmap option to collapse all depths greater than 2, which results in a tri-state value visible in the output of 'qemu-img map --output=json' (yes, that means x-dirty-bitmap is now a bit of a misnomer, but I didn't feel like renaming it as it would introduce a needless break of back-compat, even though we make no compat guarantees with x- members): unallocated (depth 0) => "zero":false, "data":true local (depth 1) => "zero":false, "data":false backing (depth 2+) => "zero":true, "data":true libnbd as client is probably a nicer way to get at the information without having to decipher such hacks in qemu as client. ;) Signed-off-by: Eric Blake <eblake@redhat.com> Message-Id: <20201027050556.269064-11-eblake@redhat.com> Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
2020-10-09block/nbd: nbd_co_reconnect_loop(): don't connect if drainedVladimir Sementsov-Ogievskiy1-0/+3
In a recent commit 12c75e20a269ac we've improved nbd_co_reconnect_loop() to not make drain wait for additional sleep. Similarly, we shouldn't try to connect, if previous sleep was interrupted by drain begin, otherwise drain_begin will have to wait for the whole connection attempt. Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Message-Id: <20200903190301.367620-5-vsementsov@virtuozzo.com> Reviewed-by: Eric Blake <eblake@redhat.com> Signed-off-by: Eric Blake <eblake@redhat.com>
2020-10-09block/nbd: fix reconnect-delayVladimir Sementsov-Ogievskiy1-9/+50
reconnect-delay has a design flaw: we handle it in the same loop where we do connection attempt. So, reconnect-delay may be exceeded by unpredictable time of connection attempt. Let's instead use separate timer. How to reproduce the bug: 1. Create an image on node1: qemu-img create -f qcow2 xx 100M 2. Start NBD server on node1: qemu-nbd xx 3. On node2 start qemu-io: ./build/qemu-io --image-opts \ driver=nbd,server.type=inet,server.host=192.168.100.5,server.port=10809,reconnect-delay=15 4. Type 'read 0 512' in qemu-io interface to check that connection works Be careful: you should make steps 5-7 in a short time, less than 15 seconds. 5. Kill nbd server on node1 6. Run 'read 0 512' in qemu-io interface again, to be sure that nbd client goes to reconnect loop. 7. On node1 run the following command sudo iptables -A INPUT -p tcp --dport 10809 -j DROP This will make the connect() call of qemu-io at node2 take a long time. And you'll see that read command in qemu-io will hang for a long time, more than 15 seconds specified by reconnect-delay parameter. It's the bug. 8. Don't forget to drop iptables rule on node1: sudo iptables -D INPUT -p tcp --dport 10809 -j DROP Important note: Step [5] is necessary to reproduce _this_ bug. If we miss step [5], the read command (step 6) will hang for a long time and this commit doesn't help, because there will be not long connect() to unreachable host, but long sendmsg() to unreachable host, which should be fixed by enabling and adjusting keep-alive on the socket, which is a thing for further patch set. Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Message-Id: <20200903190301.367620-4-vsementsov@virtuozzo.com> Reviewed-by: Eric Blake <eblake@redhat.com> Signed-off-by: Eric Blake <eblake@redhat.com>
2020-10-09block/nbd: correctly use qio_channel_detach_aio_context when neededVladimir Sementsov-Ogievskiy1-2/+2
Don't use nbd_client_detach_aio_context() driver handler where we want to finalize the connection. We should directly use qio_channel_detach_aio_context() in such cases. Driver handler may (and will) contain another things, unrelated to the qio channel. Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Message-Id: <20200903190301.367620-3-vsementsov@virtuozzo.com> Reviewed-by: Eric Blake <eblake@redhat.com> Signed-off-by: Eric Blake <eblake@redhat.com>
2020-10-09block/nbd: fix drain dead-lock because of nbd reconnect-delayVladimir Sementsov-Ogievskiy1-0/+5
We pause reconnect process during drained section. So, if we have some requests, waiting for reconnect we should cancel them, otherwise they deadlock the drained section. How to reproduce: 1. Create an image: qemu-img create -f qcow2 xx 100M 2. Start NBD server: qemu-nbd xx 3. Start vm with second nbd disk on node2, like this: ./build/x86_64-softmmu/qemu-system-x86_64 -nodefaults -drive \ file=/work/images/cent7.qcow2 -drive \ driver=nbd,server.type=inet,server.host=192.168.100.5,server.port=10809,reconnect-delay=60 \ -vnc :0 -m 2G -enable-kvm -vga std 4. Access the vm through vnc (or some other way?), and check that NBD drive works: dd if=/dev/sdb of=/dev/null bs=1M count=10 - the command should succeed. 5. Now, kill the nbd server, and run dd in the guest again: dd if=/dev/sdb of=/dev/null bs=1M count=10 Now Qemu is trying to reconnect, and dd-generated requests are waiting for the connection (they will wait up to 60 seconds (see reconnect-delay option above) and than fail). But suddenly, vm may totally hang in the deadlock. You may need to increase reconnect-delay period to catch the dead-lock. VM doesn't respond because drain dead-lock happens in cpu thread with global mutex taken. That's not good thing by itself and is not fixed by this commit (true way is using iothreads). Still this commit fixes drain dead-lock itself. Note: probably, we can instead continue to reconnect during drained section. To achieve this, we may move negotiation to the connect thread to make it independent of bs aio context. But expanding drained section doesn't seem good anyway. So, let's now fix the bug the simplest way. Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Message-Id: <20200903190301.367620-2-vsementsov@virtuozzo.com> Reviewed-by: Eric Blake <eblake@redhat.com> Signed-off-by: Eric Blake <eblake@redhat.com>
2020-09-02block/nbd: use non-blocking connect: fix vm hang on connect()Vladimir Sementsov-Ogievskiy1-1/+265
This makes nbd's connection_co yield during reconnects, so that reconnect doesn't block the main thread. This is very important in case of an unavailable nbd server host: connect() call may take a long time, blocking the main thread (and due to reconnect, it will hang again and again with small gaps of working time during pauses between connection attempts). Realization notes: - We don't want to implement non-blocking connect() over non-blocking socket, because getaddrinfo() doesn't have portable non-blocking realization anyway, so let's just use a thread for both getaddrinfo() and connect(). - We can't use qio_channel_socket_connect_async (which behaves similarly and starts a thread to execute connect() call), as it's relying on someone iterating main loop (g_main_loop_run() or something like this), which is not always the case. - We can't use thread_pool_submit_co API, as thread pool waits for all threads to finish (but we don't want to wait for blocking reconnect attempt on shutdown. So, we just create the thread by hand. Some additional difficulties are: - We want our connect to avoid blocking drained sections and aio context switches. To achieve this, we make it possible to "cancel" synchronous wait for the connect (which is a coroutine yield actually), still, the thread continues in background, and if successful, its result may be reused on next reconnect attempt. - We don't want to wait for reconnect on shutdown, so there is CONNECT_THREAD_RUNNING_DETACHED thread state, which means that the block layer is no longer interested in a result, and thread should close new connected socket on finish and free the state. How to reproduce the bug, fixed with this commit: 1. Create an image on node1: qemu-img create -f qcow2 xx 100M 2. Start NBD server on node1: qemu-nbd xx 3. Start vm with second nbd disk on node2, like this: ./x86_64-softmmu/qemu-system-x86_64 -nodefaults -drive \ file=/work/images/cent7.qcow2 -drive file=nbd+tcp://192.168.100.2 \ -vnc :0 -qmp stdio -m 2G -enable-kvm -vga std 4. Access the vm through vnc (or some other way?), and check that NBD drive works: dd if=/dev/sdb of=/dev/null bs=1M count=10 - the command should succeed. 5. Now, let's trigger nbd-reconnect loop in Qemu process. For this: 5.1 Kill NBD server on node1 5.2 run "dd if=/dev/sdb of=/dev/null bs=1M count=10" in the guest again. The command should fail and a lot of error messages about failing disk may appear as well. Now NBD client driver in Qemu tries to reconnect. Still, VM works well. 6. Make node1 unavailable on NBD port, so connect() from node2 will last for a long time: On node1 (Note, that 10809 is just a default NBD port): sudo iptables -A INPUT -p tcp --dport 10809 -j DROP After some time the guest hangs, and you may check in gdb that Qemu hangs in connect() call, issued from the main thread. This is the BUG. 7. Don't forget to drop iptables rule from your node1: sudo iptables -D INPUT -p tcp --dport 10809 -j DROP Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Message-Id: <20200812145237.4396-1-vsementsov@virtuozzo.com> Reviewed-by: Eric Blake <eblake@redhat.com> [eblake: minor wording and formatting tweaks] Signed-off-by: Eric Blake <eblake@redhat.com>
2020-07-28block/nbd: nbd_co_reconnect_loop(): don't sleep if drainedVladimir Sementsov-Ogievskiy1-5/+6
We try to go to wakeable sleep, so that, if drain begins it will break the sleep. But what if nbd_client_co_drain_begin() already called and s->drained is already true? We'll go to sleep, and drain will have to wait for the whole timeout. Let's improve it. Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Reviewed-by: Eric Blake <eblake@redhat.com> Message-Id: <20200727184751.15704-5-vsementsov@virtuozzo.com> Signed-off-by: Eric Blake <eblake@redhat.com>
2020-07-28block/nbd: on shutdown terminate connection attemptVladimir Sementsov-Ogievskiy1-4/+11
On shutdown nbd driver may be in a connecting state. We should shutdown it as well, otherwise we may hang in nbd_teardown_connection, waiting for conneciton_co to finish in BDRV_POLL_WHILE(bs, s->connection_co) loop if remote server is down. How to reproduce the dead lock: 1. Create nbd-fault-injector.conf with the following contents: [inject-error "mega1"] event=data io=readwrite when=before 2. In one terminal run nbd-fault-injector in a loop, like this: n=1; while true; do echo $n; ((n++)); ./nbd-fault-injector.py 127.0.0.1:10000 nbd-fault-injector.conf; done 3. In another terminal run qemu-io in a loop, like this: n=1; while true; do echo $n; ((n++)); ./qemu-io -c 'read 0 512' nbd://127.0.0.1:10000; done After some time, qemu-io will hang. Note, that this hang may be triggered by another bug, so the whole case is fixed only together with commit "block/nbd: allow drain during reconnect attempt". Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Reviewed-by: Eric Blake <eblake@redhat.com> Message-Id: <20200727184751.15704-4-vsementsov@virtuozzo.com> Signed-off-by: Eric Blake <eblake@redhat.com>
2020-07-28block/nbd: allow drain during reconnect attemptVladimir Sementsov-Ogievskiy1-0/+14
It should be safe to reenter qio_channel_yield() on io/channel read/write path, so it's safe to reduce in_flight and allow attaching new aio context. And no problem to allow drain itself: connection attempt is not a guest request. Moreover, if remote server is down, we can hang in negotiation, blocking drain section and provoking a dead lock. How to reproduce the dead lock: 1. Create nbd-fault-injector.conf with the following contents: [inject-error "mega1"] event=data io=readwrite when=before 2. In one terminal run nbd-fault-injector in a loop, like this: n=1; while true; do echo $n; ((n++)); ./nbd-fault-injector.py 127.0.0.1:10000 nbd-fault-injector.conf; done 3. In another terminal run qemu-io in a loop, like this: n=1; while true; do echo $n; ((n++)); ./qemu-io -c 'read 0 512' nbd://127.0.0.1:10000; done After some time, qemu-io will hang trying to drain, for example, like this: #3 aio_poll (ctx=0x55f006bdd890, blocking=true) at util/aio-posix.c:600 #4 bdrv_do_drained_begin (bs=0x55f006bea710, recursive=false, parent=0x0, ignore_bds_parents=false, poll=true) at block/io.c:427 #5 bdrv_drained_begin (bs=0x55f006bea710) at block/io.c:433 #6 blk_drain (blk=0x55f006befc80) at block/block-backend.c:1710 #7 blk_unref (blk=0x55f006befc80) at block/block-backend.c:498 #8 bdrv_open_inherit (filename=0x7fffba1563bc "nbd+tcp://127.0.0.1:10000", reference=0x0, options=0x55f006be86d0, flags=24578, parent=0x0, child_class=0x0, child_role=0, errp=0x7fffba154620) at block.c:3491 #9 bdrv_open (filename=0x7fffba1563bc "nbd+tcp://127.0.0.1:10000", reference=0x0, options=0x0, flags=16386, errp=0x7fffba154620) at block.c:3513 #10 blk_new_open (filename=0x7fffba1563bc "nbd+tcp://127.0.0.1:10000", reference=0x0, options=0x0, flags=16386, errp=0x7fffba154620) at block/block-backend.c:421 And connection_co stack like this: #0 qemu_coroutine_switch (from_=0x55f006bf2650, to_=0x7fe96e07d918, action=COROUTINE_YIELD) at util/coroutine-ucontext.c:302 #1 qemu_coroutine_yield () at util/qemu-coroutine.c:193 #2 qio_channel_yield (ioc=0x55f006bb3c20, condition=G_IO_IN) at io/channel.c:472 #3 qio_channel_readv_all_eof (ioc=0x55f006bb3c20, iov=0x7fe96d729bf0, niov=1, errp=0x7fe96d729eb0) at io/channel.c:110 #4 qio_channel_readv_all (ioc=0x55f006bb3c20, iov=0x7fe96d729bf0, niov=1, errp=0x7fe96d729eb0) at io/channel.c:143 #5 qio_channel_read_all (ioc=0x55f006bb3c20, buf=0x7fe96d729d28 "\300.\366\004\360U", buflen=8, errp=0x7fe96d729eb0) at io/channel.c:247 #6 nbd_read (ioc=0x55f006bb3c20, buffer=0x7fe96d729d28, size=8, desc=0x55f004f69644 "initial magic", errp=0x7fe96d729eb0) at /work/src/qemu/master/include/block/nbd.h:365 #7 nbd_read64 (ioc=0x55f006bb3c20, val=0x7fe96d729d28, desc=0x55f004f69644 "initial magic", errp=0x7fe96d729eb0) at /work/src/qemu/master/include/block/nbd.h:391 #8 nbd_start_negotiate (aio_context=0x55f006bdd890, ioc=0x55f006bb3c20, tlscreds=0x0, hostname=0x0, outioc=0x55f006bf19f8, structured_reply=true, zeroes=0x7fe96d729dca, errp=0x7fe96d729eb0) at nbd/client.c:904 #9 nbd_receive_negotiate (aio_context=0x55f006bdd890, ioc=0x55f006bb3c20, tlscreds=0x0, hostname=0x0, outioc=0x55f006bf19f8, info=0x55f006bf1a00, errp=0x7fe96d729eb0) at nbd/client.c:1032 #10 nbd_client_connect (bs=0x55f006bea710, errp=0x7fe96d729eb0) at block/nbd.c:1460 #11 nbd_reconnect_attempt (s=0x55f006bf19f0) at block/nbd.c:287 #12 nbd_co_reconnect_loop (s=0x55f006bf19f0) at block/nbd.c:309 #13 nbd_connection_entry (opaque=0x55f006bf19f0) at block/nbd.c:360 #14 coroutine_trampoline (i0=113190480, i1=22000) at util/coroutine-ucontext.c:173 Note, that the hang may be triggered by another bug, so the whole case is fixed only together with commit "block/nbd: on shutdown terminate connection attempt". Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Message-Id: <20200727184751.15704-3-vsementsov@virtuozzo.com> Reviewed-by: Eric Blake <eblake@redhat.com> Signed-off-by: Eric Blake <eblake@redhat.com>
2020-07-28block/nbd: split nbd_establish_connection out of nbd_client_connectVladimir Sementsov-Ogievskiy1-24/+36
We are going to implement non-blocking version of nbd_establish_connection, which for a while will be used only for nbd_reconnect_attempt, not for nbd_open, so we need to call it separately. Refactor nbd_reconnect_attempt in a way which makes next commit simpler. Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Message-Id: <20200727184751.15704-2-vsementsov@virtuozzo.com> Reviewed-by: Eric Blake <eblake@redhat.com> Signed-off-by: Eric Blake <eblake@redhat.com>
2020-07-28block: nbd: Fix convert qcow2 compressed to nbdNir Soffer1-0/+30
When converting to qcow2 compressed format, the last step is a special zero length compressed write, ending in a call to bdrv_co_truncate(). This call always fails for the nbd driver since it does not implement bdrv_co_truncate(). For block devices, which have the same limits, the call succeeds since the file driver implements bdrv_co_truncate(). If the caller asked to truncate to the same or smaller size with exact=false, the truncate succeeds. Implement the same logic for nbd. Example failing without this change: In one shell start qemu-nbd: $ truncate -s 1g test.tar $ qemu-nbd --socket=/tmp/nbd.sock --persistent --format=raw --offset 1536 test.tar In another shell convert an image to qcow2 compressed via NBD: $ echo "disk data" > disk.raw $ truncate -s 1g disk.raw $ qemu-img convert -f raw -O qcow2 -c disk1.raw nbd+unix:///?socket=/tmp/nbd.sock; echo $? 1 qemu-img failed, but the conversion was successful: $ qemu-img info nbd+unix:///?socket=/tmp/nbd.sock image: nbd+unix://?socket=/tmp/nbd.sock file format: qcow2 virtual size: 1 GiB (1073741824 bytes) ... $ qemu-img check nbd+unix:///?socket=/tmp/nbd.sock No errors were found on the image. 1/16384 = 0.01% allocated, 100.00% fragmented, 100.00% compressed clusters Image end offset: 393216 $ qemu-img compare disk.raw nbd+unix:///?socket=/tmp/nbd.sock Images are identical. Fixes: https://bugzilla.redhat.com/1860627 Signed-off-by: Nir Soffer <nsoffer@redhat.com> Message-Id: <20200727215846.395443-2-nsoffer@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com> Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> [eblake: typo fixes] Signed-off-by: Eric Blake <eblake@redhat.com>
2020-07-13nbd: Avoid off-by-one in long export name truncationEric Blake1-1/+1
When snprintf returns the same value as the buffer size, the final byte was truncated to ensure a NUL terminator. Fortunately, such long export names are unusual enough, with no real impact other than what is displayed to the user. Fixes: 5c86bdf12089 Reported-by: Max Reitz <mreitz@redhat.com> Signed-off-by: Eric Blake <eblake@redhat.com> Message-Id: <20200622210355.414941-1-eblake@redhat.com> Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
2020-07-10nbd: Use ERRP_GUARD()Vladimir Sementsov-Ogievskiy1-4/+3
If we want to check error after errp-function call, we need to introduce local_err and then propagate it to errp. Instead, use the ERRP_GUARD() macro, benefits are: 1. No need of explicit error_propagate call 2. No need of explicit local_err variable: use errp directly 3. ERRP_GUARD() leaves errp as is if it's not NULL or &error_fatal, this means that we don't break error_abort (we'll abort on error_set, not on error_propagate) If we want to add some info to errp (by error_prepend() or error_append_hint()), we must use the ERRP_GUARD() macro. Otherwise, this info will not be added when errp == &error_fatal (the program will exit prior to the error_append_hint() or error_prepend() call). Fix several such cases, e.g. in nbd_read(). This commit is generated by command sed -n '/^Network Block Device (NBD)$/,/^$/{s/^F: //p}' \ MAINTAINERS | \ xargs git ls-files | grep '\.[hc]$' | \ xargs spatch \ --sp-file scripts/coccinelle/errp-guard.cocci \ --macro-file scripts/cocci-macro-file.h \ --in-place --no-show-diff --max-width 80 Reported-by: Kevin Wolf <kwolf@redhat.com> Reported-by: Greg Kurz <groug@kaod.org> Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Reviewed-by: Markus Armbruster <armbru@redhat.com> [Commit message tweaked] Signed-off-by: Markus Armbruster <armbru@redhat.com> Message-Id: <20200707165037.1026246-8-armbru@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com> [ERRP_AUTO_PROPAGATE() renamed to ERRP_GUARD(), and auto-propagated-errp.cocci to errp-guard.cocci. Commit message tweaked again.]
2020-07-10error: Eliminate error_propagate() with Coccinelle, part 2Markus Armbruster1-6/+2
When all we do with an Error we receive into a local variable is propagating to somewhere else, we can just as well receive it there right away. The previous commit did that with a Coccinelle script I consider fairly trustworthy. This commit uses the same script with the matching of return taken out, i.e. we convert if (!foo(..., &err)) { ... error_propagate(errp, err); ... } to if (!foo(..., errp)) { ... ... } This is unsound: @err could still be read between afterwards. I don't know how to express "no read of @err without an intervening write" in Coccinelle. Instead, I manually double-checked for uses of @err. Suboptimal line breaks tweaked manually. qdev_realize() simplified further to placate scripts/checkpatch.pl. Signed-off-by: Markus Armbruster <armbru@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com> Message-Id: <20200707160613.848843-36-armbru@redhat.com>
2020-07-10qapi: Use returned bool to check for failure, Coccinelle partMarkus Armbruster1-2/+1
The previous commit enables conversion of visit_foo(..., &err); if (err) { ... } to if (!visit_foo(..., errp)) { ... } for visitor functions that now return true / false on success / error. Coccinelle script: @@ identifier fun =~ "check_list|input_type_enum|lv_start_struct|lv_type_bool|lv_type_int64|lv_type_str|lv_type_uint64|output_type_enum|parse_type_bool|parse_type_int64|parse_type_null|parse_type_number|parse_type_size|parse_type_str|parse_type_uint64|print_type_bool|print_type_int64|print_type_null|print_type_number|print_type_size|print_type_str|print_type_uint64|qapi_clone_start_alternate|qapi_clone_start_list|qapi_clone_start_struct|qapi_clone_type_bool|qapi_clone_type_int64|qapi_clone_type_null|qapi_clone_type_number|qapi_clone_type_str|qapi_clone_type_uint64|qapi_dealloc_start_list|qapi_dealloc_start_struct|qapi_dealloc_type_anything|qapi_dealloc_type_bool|qapi_dealloc_type_int64|qapi_dealloc_type_null|qapi_dealloc_type_number|qapi_dealloc_type_str|qapi_dealloc_type_uint64|qobject_input_check_list|qobject_input_check_struct|qobject_input_start_alternate|qobject_input_start_list|qobject_input_start_struct|qobject_input_type_any|qobject_input_type_bool|qobject_input_type_bool_keyval|qobject_input_type_int64|qobject_input_type_int64_keyval|qobject_input_type_null|qobject_input_type_number|qobject_input_type_number_keyval|qobject_input_type_size_keyval|qobject_input_type_str|qobject_input_type_str_keyval|qobject_input_type_uint64|qobject_input_type_uint64_keyval|qobject_output_start_list|qobject_output_start_struct|qobject_output_type_any|qobject_output_type_bool|qobject_output_type_int64|qobject_output_type_null|qobject_output_type_number|qobject_output_type_str|qobject_output_type_uint64|start_list|visit_check_list|visit_check_struct|visit_start_alternate|visit_start_list|visit_start_struct|visit_type_.*"; expression list args; typedef Error; Error *err; @@ - fun(args, &err); - if (err) + if (!fun(args, &err)) { ... } A few line breaks tidied up manually. Signed-off-by: Markus Armbruster <armbru@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com> Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Message-Id: <20200707160613.848843-19-armbru@redhat.com>
2020-07-10qemu-option: Use returned bool to check for failureMarkus Armbruster1-2/+1
The previous commit enables conversion of foo(..., &err); if (err) { ... } to if (!foo(..., &err)) { ... } for QemuOpts functions that now return true / false on success / error. Coccinelle script: @@ identifier fun = { opts_do_parse, parse_option_bool, parse_option_number, parse_option_size, qemu_opt_parse, qemu_opt_rename, qemu_opt_set, qemu_opt_set_bool, qemu_opt_set_number, qemu_opts_absorb_qdict, qemu_opts_do_parse, qemu_opts_from_qdict_entry, qemu_opts_set, qemu_opts_validate }; expression list args, args2; typedef Error; Error *err; @@ - fun(args, &err, args2); - if (err) + if (!fun(args, &err, args2)) { ... } A few line breaks tidied up manually. Signed-off-by: Markus Armbruster <armbru@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com> Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Message-Id: <20200707160613.848843-15-armbru@redhat.com> [Conflict with commit 0b6786a9c1 "block/amend: refactor qcow2 amend options" resolved by rerunning Coccinelle on master's version]
2020-06-10block: Call attention to truncation of long NBD exportsEric Blake1-8/+13
Commit 93676c88 relaxed our NBD client code to request export names up to the NBD protocol maximum of 4096 bytes without NUL terminator, even though the block layer can't store anything longer than 4096 bytes including NUL terminator for display to the user. Since this means there are some export names where we have to truncate things, we can at least try to make the truncation a bit more obvious for the user. Note that in spite of the truncated display name, we can still communicate with an NBD server using such a long export name; this was deemed nicer than refusing to even connect to such a server (since the server may not be under our control, and since determining our actual length limits gets tricky when nbd://host:port/export and nbd+unix:///export?socket=/path are themselves variable-length expansions beyond the export name but count towards the block layer name length). Reported-by: Xueqiang Wei <xuwei@redhat.com> Fixes: https://bugzilla.redhat.com/1843684 Signed-off-by: Eric Blake <eblake@redhat.com> Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Message-Id: <20200610163741.3745251-3-eblake@redhat.com>
2020-05-04block/nbd-client: drop max_block restriction from discardVladimir Sementsov-Ogievskiy1-1/+1
The NBD spec was updated (see nbd.git commit 9f30fedb) so that max_block doesn't relate to NBD_CMD_TRIM. So, drop the restriction. Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Message-Id: <20200401150112.9557-3-vsementsov@virtuozzo.com> Reviewed-by: Eric Blake <eblake@redhat.com> [eblake: tweak commit message to call out NBD commit] Signed-off-by: Eric Blake <eblake@redhat.com>
2020-05-04block/nbd-client: drop max_block restriction from block_statusVladimir Sementsov-Ogievskiy1-3/+1
The NBD spec was updated (see nbd.git commit 9f30fedb) so that max_block doesn't relate to NBD_CMD_BLOCK_STATUS. So, drop the restriction. Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Reviewed-by: Eric Blake <eblake@redhat.com> Message-Id: <20200401150112.9557-2-vsementsov@virtuozzo.com> [eblake: tweak commit message to call out NBD commit] Signed-off-by: Eric Blake <eblake@redhat.com>
2020-03-26block: trickle down the fallback image creation function use to the block ↵Maxim Levitsky1-0/+6
drivers Instead of checking the .bdrv_co_create_opts to see if we need the fallback, just implement the .bdrv_co_create_opts in the drivers that need it. This way we don't break various places that need to know if the underlying protocol/format really supports image creation, and this way we still allow some drivers to not support image creation. Fixes: fd17146cd93d1704cd96d7c2757b325fc7aac6fd Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1816007 Note that technically this driver reverts the image creation fallback for the vxhs driver since I don't have a means to test it, and IMHO it is better to leave it not supported as it was prior to generic image creation patches. Also drop iscsi_create_opts which was left accidentally. Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com> Message-Id: <20200326011218.29230-3-mlevitsk@redhat.com> Reviewed-by: Denis V. Lunev <den@openvz.org> [mreitz: Fixed alignment, and moved bdrv_co_create_opts_simple() and bdrv_create_opts_simple from block.h into block_int.h] Signed-off-by: Max Reitz <mreitz@redhat.com>
2020-02-26block/nbd: fix memory leak in nbd_open()Pan Nengyuan1-0/+1
In currently implementation there will be a memory leak when nbd_client_connect() returns error status. Here is an easy way to reproduce: 1. run qemu-iotests as follow and check the result with asan: ./check -raw 143 Following is the asan output backtrack: Direct leak of 40 byte(s) in 1 object(s) allocated from: #0 0x7f629688a560 in calloc (/usr/lib64/libasan.so.3+0xc7560) #1 0x7f6295e7e015 in g_malloc0 (/usr/lib64/libglib-2.0.so.0+0x50015) #2 0x56281dab4642 in qobject_input_start_struct /mnt/sdb/qemu-4.2.0-rc0/qapi/qobject-input-visitor.c:295 #3 0x56281dab1a04 in visit_start_struct /mnt/sdb/qemu-4.2.0-rc0/qapi/qapi-visit-core.c:49 #4 0x56281dad1827 in visit_type_SocketAddress qapi/qapi-visit-sockets.c:386 #5 0x56281da8062f in nbd_config /mnt/sdb/qemu-4.2.0-rc0/block/nbd.c:1716 #6 0x56281da8062f in nbd_process_options /mnt/sdb/qemu-4.2.0-rc0/block/nbd.c:1829 #7 0x56281da8062f in nbd_open /mnt/sdb/qemu-4.2.0-rc0/block/nbd.c:1873 Direct leak of 15 byte(s) in 1 object(s) allocated from: #0 0x7f629688a3a0 in malloc (/usr/lib64/libasan.so.3+0xc73a0) #1 0x7f6295e7dfbd in g_malloc (/usr/lib64/libglib-2.0.so.0+0x4ffbd) #2 0x7f6295e96ace in g_strdup (/usr/lib64/libglib-2.0.so.0+0x68ace) #3 0x56281da804ac in nbd_process_options /mnt/sdb/qemu-4.2.0-rc0/block/nbd.c:1834 #4 0x56281da804ac in nbd_open /mnt/sdb/qemu-4.2.0-rc0/block/nbd.c:1873 Indirect leak of 24 byte(s) in 1 object(s) allocated from: #0 0x7f629688a3a0 in malloc (/usr/lib64/libasan.so.3+0xc73a0) #1 0x7f6295e7dfbd in g_malloc (/usr/lib64/libglib-2.0.so.0+0x4ffbd) #2 0x7f6295e96ace in g_strdup (/usr/lib64/libglib-2.0.so.0+0x68ace) #3 0x56281dab41a3 in qobject_input_type_str_keyval /mnt/sdb/qemu-4.2.0-rc0/qapi/qobject-input-visitor.c:536 #4 0x56281dab2ee9 in visit_type_str /mnt/sdb/qemu-4.2.0-rc0/qapi/qapi-visit-core.c:297 #5 0x56281dad0fa1 in visit_type_UnixSocketAddress_members qapi/qapi-visit-sockets.c:141 #6 0x56281dad17b6 in visit_type_SocketAddress_members qapi/qapi-visit-sockets.c:366 #7 0x56281dad186a in visit_type_SocketAddress qapi/qapi-visit-sockets.c:393 #8 0x56281da8062f in nbd_config /mnt/sdb/qemu-4.2.0-rc0/block/nbd.c:1716 #9 0x56281da8062f in nbd_process_options /mnt/sdb/qemu-4.2.0-rc0/block/nbd.c:1829 #10 0x56281da8062f in nbd_open /mnt/sdb/qemu-4.2.0-rc0/block/nbd.c:1873 Fixes: 8f071c9db506e03ab Reported-by: Euler Robot <euler.robot@huawei.com> Signed-off-by: Pan Nengyuan <pannengyuan@huawei.com> Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Cc: qemu-stable <qemu-stable@nongnu.org> Cc: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Message-Id: <1575517528-44312-3-git-send-email-pannengyuan@huawei.com> Reviewed-by: Stefano Garzarella <sgarzare@redhat.com> Signed-off-by: Eric Blake <eblake@redhat.com>
2020-02-26block/nbd: extract the common cleanup codePan Nengyuan1-11/+15
The BDRVNBDState cleanup code is common in two places, add nbd_clear_bdrvstate() function to do these cleanups. Suggested-by: Stefano Garzarella <sgarzare@redhat.com> Signed-off-by: Pan Nengyuan <pannengyuan@huawei.com> Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Message-Id: <1575517528-44312-2-git-send-email-pannengyuan@huawei.com> Reviewed-by: Eric Blake <eblake@redhat.com> [eblake: fix compilation error and commit message] Signed-off-by: Eric Blake <eblake@redhat.com>
2020-02-26nbd-client: Support leading / in NBD URIEric Blake1-2/+4
The NBD URI specification [1] states that only one leading slash at the beginning of the URI path component is stripped, not all such slashes. This becomes important to a patch I just proposed to nbdkit [2], which would allow the exportname to select a file embedded within an ext2 image: ext2fs demands an absolute pathname beginning with '/', and because qemu was inadvertantly stripping it, my nbdkit patch had to work around the behavior. [1] https://github.com/NetworkBlockDevice/nbd/blob/master/doc/uri.md [2] https://www.redhat.com/archives/libguestfs/2020-February/msg00109.html Note that the qemu bug only affects handling of URIs such as nbd://host:port//abs/path (where '/abs/path' should be the export name); it is still possible to use --image-opts and pass the desired export name with a leading slash directly through JSON even without this patch. Signed-off-by: Eric Blake <eblake@redhat.com> Message-Id: <20200212023101.1162686-1-eblake@redhat.com> Reviewed-by: Ján Tomko <jtomko@redhat.com>
2020-02-20block/nbd: Fix hang in .bdrv_close()Max Reitz1-1/+13
When nbd_close() is called from a coroutine, the connection_co never gets to run, and thus nbd_teardown_connection() hangs. This is because aio_co_enter() only puts the connection_co into the main coroutine's wake-up queue, so this main coroutine needs to yield and wait for connection_co to terminate. Suggested-by: Kevin Wolf <kwolf@redhat.com> Signed-off-by: Max Reitz <mreitz@redhat.com> Message-Id: <20200122164532.178040-2-mreitz@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com> Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com> Signed-off-by: Max Reitz <mreitz@redhat.com>
2019-12-18nbd: assert that Error** is not NULL in nbd_iter_channel_errorVladimir Sementsov-Ogievskiy1-0/+1
All callers of nbd_iter_channel_error() pass the address of a local_err variable, and only call this function if an error has already occurred, using this function to propagate that error. This is already implied by its name (local_err instead of the classic errp), but it is worth additionally stressing this by adding an assertion to make it part of the function contract. The local_err parameter is not here to return information about nbd_iter_channel_error failure. Instead it's assumed to be filled when passed to the function. This is already stressed by its name (local_err, instead of classic errp). Stress it additionally by assertion. Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Message-Id: <20191205174635.18758-22-vsementsov@virtuozzo.com> Reviewed-by: Eric Blake <eblake@redhat.com> Reviewed-by: Markus Armbruster <armbru@redhat.com> Signed-off-by: Markus Armbruster <armbru@redhat.com>
2019-11-18nbd: Don't send oversize stringsEric Blake1-0/+10
Qemu as server currently won't accept export names larger than 256 bytes, nor create dirty bitmap names longer than 1023 bytes, so most uses of qemu as client or server have no reason to get anywhere near the NBD spec maximum of a 4k limit per string. However, we weren't actually enforcing things, ignoring when the remote side violates the protocol on input, and also having several code paths where we send oversize strings on output (for example, qemu-nbd --description could easily send more than 4k). Tighten things up as follows: client: - Perform bounds check on export name and dirty bitmap request prior to handing it to server - Validate that copied server replies are not too long (ignoring NBD_INFO_* replies that are not copied is not too bad) server: - Perform bounds check on export name and description prior to advertising it to client - Reject client name or metadata query that is too long - Adjust things to allow full 4k name limit rather than previous 256 byte limit Signed-off-by: Eric Blake <eblake@redhat.com> Message-Id: <20191114024635.11363-4-eblake@redhat.com> Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com> Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
2019-10-22block/nbd: nbd reconnectVladimir Sementsov-Ogievskiy1-63/+268
Implement reconnect. To achieve this: 1. add new modes: connecting-wait: means, that reconnecting is in progress, and there were small number of reconnect attempts, so all requests are waiting for the connection. connecting-nowait: reconnecting is in progress, there were a lot of attempts of reconnect, all requests will return errors. two old modes are used too: connected: normal state quit: exiting after fatal error or on close Possible transitions are: * -> quit connecting-* -> connected connecting-wait -> connecting-nowait (transition is done after reconnect-delay seconds in connecting-wait mode) connected -> connecting-wait 2. Implement reconnect in connection_co. So, in connecting-* mode, connection_co, tries to reconnect unlimited times. 3. Retry nbd queries on channel error, if we are in connecting-wait state. Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Message-Id: <20191009084158.15614-3-vsementsov@virtuozzo.com> Reviewed-by: Eric Blake <eblake@redhat.com> Signed-off-by: Eric Blake <eblake@redhat.com>
2019-10-10nbd: add empty .bdrv_reopen_prepareMaxim Levitsky1-0/+15
Fixes commit job / qemu-img commit, when commiting qcow2 file which is based on nbd export. Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1718727 Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com> Message-id: 20190930213820.29777-2-mlevitsk@redhat.com Signed-off-by: Max Reitz <mreitz@redhat.com>
2019-09-05nbd: Implement client use of NBD FAST_ZEROEric Blake1-0/+7
The client side is fairly straightforward: if the server advertised fast zero support, then we can map that to BDRV_REQ_NO_FALLBACK support. A server that advertises FAST_ZERO but not WRITE_ZEROES is technically broken, but we can ignore that situation as it does not change our behavior. Signed-off-by: Eric Blake <eblake@redhat.com> Message-Id: <20190823143726.27062-4-eblake@redhat.com> Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
2019-09-05nbd: Use g_autofree in a few placesEric Blake1-7/+4
Thanks to our recent move to use glib's g_autofree, I can join the bandwagon. Getting rid of gotos is fun ;) There are probably more places where we could register cleanup functions and get rid of more gotos; this patch just focuses on the labels that existed merely to call g_free. Signed-off-by: Eric Blake <eblake@redhat.com> Message-Id: <20190824172813.29720-2-eblake@redhat.com> Reviewed-by: Daniel P. Berrangé <berrange@redhat.com> Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
2019-08-16Merge remote-tracking branch 'remotes/ericb/tags/pull-nbd-2019-08-15' into ↵Peter Maydell1-82/+113
staging nbd patches for 2019-08-15 - Addition of InetSocketAddress keep-alive - Addition of BDRV_REQ_PREFETCH for more efficient copy-on-read - Initial refactoring in preparation of NBD reconnect # gpg: Signature made Thu 15 Aug 2019 19:28:41 BST # gpg: using RSA key A7A16B4A2527436A # gpg: Good signature from "Eric Blake <eblake@redhat.com>" [full] # gpg: aka "Eric Blake (Free Software Programmer) <ebb9@byu.net>" [full] # gpg: aka "[jpeg image of size 6874]" [full] # Primary key fingerprint: 71C2 CC22 B1C4 6029 27D2 F3AA A7A1 6B4A 2527 436A * remotes/ericb/tags/pull-nbd-2019-08-15: block/nbd: refactor nbd connection parameters block/nbd: add cmdline and qapi parameter reconnect-delay block/nbd: move from quit to state block/nbd: use non-blocking io channel for nbd negotiation block/nbd: split connection_co start out of nbd_client_connect nbd: improve CMD_CACHE: use BDRV_REQ_PREFETCH block/stream: use BDRV_REQ_PREFETCH block: implement BDRV_REQ_PREFETCH qapi: Add InetSocketAddress member keep-alive Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
2019-08-16Include qemu/main-loop.h lessMarkus Armbruster1-0/+1
In my "build everything" tree, changing qemu/main-loop.h triggers a recompile of some 5600 out of 6600 objects (not counting tests and objects that don't depend on qemu/osdep.h). It includes block/aio.h, which in turn includes qemu/event_notifier.h, qemu/notify.h, qemu/processor.h, qemu/qsp.h, qemu/queue.h, qemu/thread-posix.h, qemu/thread.h, qemu/timer.h, and a few more. Include qemu/main-loop.h only where it's needed. Touching it now recompiles only some 1700 objects. For block/aio.h and qemu/event_notifier.h, these numbers drop from 5600 to 2800. For the others, they shrink only slightly. Signed-off-by: Markus Armbruster <armbru@redhat.com> Message-Id: <20190812052359.30071-21-armbru@redhat.com> Reviewed-by: Alex Bennée <alex.bennee@linaro.org> Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com> Tested-by: Philippe Mathieu-Daudé <philmd@redhat.com>
2019-08-15block/nbd: refactor nbd connection parametersVladimir Sementsov-Ogievskiy1-61/+60
We'll need some connection parameters to be available all the time to implement nbd reconnect. So, let's refactor them: define additional parameters in BDRVNBDState, drop them from function parameters, drop nbd_client_init and separate options parsing instead from nbd_open. Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Message-Id: <20190618114328.55249-6-vsementsov@virtuozzo.com> Reviewed-by: Eric Blake <eblake@redhat.com> [eblake: Drop useless 'if' before object_unref] Signed-off-by: Eric Blake <eblake@redhat.com>
2019-08-15block/nbd: add cmdline and qapi parameter reconnect-delayVladimir Sementsov-Ogievskiy1-1/+15
Reconnect will be implemented in the following commit, so for now, in semantics below, disconnect itself is a "serious error". Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Reviewed-by: Eric Blake <eblake@redhat.com> Message-Id: <20190618114328.55249-5-vsementsov@virtuozzo.com> [eblake: slipped from 4.1 to 4.2] Signed-off-by: Eric Blake <eblake@redhat.com>
2019-08-15block/nbd: move from quit to stateVladimir Sementsov-Ogievskiy1-21/+37
To implement reconnect we need several states for the client: CONNECTED, QUIT and two different CONNECTING states. CONNECTING states will be added in the following patches. This patch implements CONNECTED and QUIT. QUIT means, that we should close the connection and fail all current and further requests (like old quit = true). CONNECTED means that connection is ok, we can send requests (like old quit = false). For receiving loop we use a comparison of the current state with QUIT, because reconnect will be in the same loop, so it should be looping until the end. Opposite, for requests we use a comparison of the current state with CONNECTED, as we don't want to send requests in future CONNECTING states. Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Reviewed-by: Eric Blake <eblake@redhat.com> Message-Id: <20190618114328.55249-4-vsementsov@virtuozzo.com> Signed-off-by: Eric Blake <eblake@redhat.com>
2019-08-15block/nbd: use non-blocking io channel for nbd negotiationVladimir Sementsov-Ogievskiy1-9/+7
No reason to use blocking channel for negotiation and we'll benefit in further reconnect feature, as qio_channel reads and writes will do qemu_coroutine_yield while waiting for io completion. Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Reviewed-by: Eric Blake <eblake@redhat.com> Message-Id: <20190618114328.55249-3-vsementsov@virtuozzo.com> Signed-off-by: Eric Blake <eblake@redhat.com>
2019-08-15block/nbd: split connection_co start out of nbd_client_connectVladimir Sementsov-Ogievskiy1-9/+13
nbd_client_connect is going to be used from connection_co, so, let's refactor nbd_client_connect in advance, leaving io channel configuration all in nbd_client_connect. Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Reviewed-by: Eric Blake <eblake@redhat.com> Message-Id: <20190618114328.55249-2-vsementsov@virtuozzo.com> Signed-off-by: Eric Blake <eblake@redhat.com>
2019-07-19nbd: Initialize reply on failureEric Blake1-3/+2
We've had two separate reports of different callers running into use of uninitialized data if s->quit is set (one detected by gcc -O3, another by valgrind), due to checking 'nbd_reply_is_simple(reply) || s->quit' in the wrong order. Rather than chasing down which callers need to pre-initialize reply, and whether there are any other uninitialized uses, it's easier to guarantee that reply will always be set by nbd_co_receive_one_chunk() even on failure. The uninitialized use happens to be harmless (the only time the variable is uninitialized is if s->quit is set, so the conditional results in the same action regardless of what was read from reply), and was introduced in commit 65e01d47. In fixing the problem, it can also be seen that all (one) callers pass in a non-NULL reply, so there is a dead conditional to also be cleaned up. Reported-by: Thomas Huth <thuth@redhat.com> Reported-by: Andrey Shinkevich <andrey.shinkevich@virtuozzo.com> Signed-off-by: Eric Blake <eblake@redhat.com> Message-Id: <20190719172001.19770-1-eblake@redhat.com> Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
2019-06-13block/nbd: merge NBDClientSession struct back to BDRVNBDStateVladimir Sementsov-Ogievskiy1-103/+94
No reason to keep it separate, it differs from others block driver behavior and therefore confuses. Instead of generic 'state = (State*)bs->opaque' we have to use special helper. Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Message-Id: <20190611102720.86114-4-vsementsov@virtuozzo.com> Reviewed-by: Eric Blake <eblake@redhat.com> Signed-off-by: Eric Blake <eblake@redhat.com>
2019-06-13block/nbd: merge nbd-client.* to nbd.cVladimir Sementsov-Ogievskiy1-32/+1253
No reason for keeping driver handlers realization separate from driver structure. We can get rid of extra header file. While being here, fix comments style, restore forgotten comments for NBD_FOREACH_REPLY_CHUNK and nbd_reply_chunk_iter_receive, remove extra includes. Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Message-Id: <20190611102720.86114-3-vsementsov@virtuozzo.com> Reviewed-by: Eric Blake <eblake@redhat.com> Signed-off-by: Eric Blake <eblake@redhat.com>
2019-03-30nbd/client: Lower min_block for block-status, unaligned sizeEric Blake1-1/+18
We have a latent bug in our NBD client code, tickled by the brand new nbdkit 1.11.10 block status support: $ nbdkit --filter=log --filter=truncate -U - \ data data="1" size=511 truncate=64K logfile=/dev/stdout \ --run 'qemu-img convert $nbd /var/tmp/out' ... qemu-img: block/io.c:2122: bdrv_co_block_status: Assertion `*pnum && QEMU_IS_ALIGNED(*pnum, align) && align > offset - aligned_offset' failed. The culprit? Our implementation of .bdrv_co_block_status can return unaligned block status for any server that operates with a lower actual alignment than what we tell the block layer in request_alignment, in violation of the block layer's constraints. To date, we've been unable to trip the bug, because qemu as NBD server always advertises block sizing (at which point it is a server bug if the server sends unaligned status - although qemu 3.1 is such a server and I've sent separate patches for 4.0 both to get the server to obey the spec, and to let the client to tolerate server oddities at EOF). But nbdkit does not (yet) advertise block sizing, and therefore is not in violation of the spec for returning block status at whatever boundaries it wants, and those unaligned results can occur anywhere rather than just at EOF. While we are still wise to avoid sending sub-sector read/write requests to a server of unknown origin, we MUST consider that a server telling us block status without an advertised block size is correct. So, we either have to munge unaligned answers from the server into aligned ones that we hand back to the block layer, or we have to tell the block layer about a smaller alignment. Similarly, if the server advertises an image size that is not sector-aligned, we might as well assume that the server intends to let us access those tail bytes, and therefore supports a minimum block size of 1, regardless of whether the server supports block status (although we still need more patches to fix the problem that with an unaligned image, we can send read or block status requests that exceed EOF to the server). Again, qemu as server cannot trip this problem (because it rounds images to sector alignment), but nbdkit advertised unaligned size even before it gained block status support. Solve both alignment problems at once by using better heuristics on what alignment to report to the block layer when the server did not give us something to work with. Note that very few NBD servers implement block status (to date, only qemu and nbdkit are known to do so); and as the NBD spec mentioned block sizing constraints prior to documenting block status, it can be assumed that any future implementations of block status are aware that they must advertise block size if they want a minimum size other than 1. We've had a long history of struggles with picking the right alignment to use in the block layer, as evidenced by the commit message of fd8d372d (v2.12) that introduced the current choice of forced 512-byte alignment. There is no iotest coverage for this fix, because qemu can't provoke it, and I didn't want to make test 241 dependent on nbdkit. Fixes: fd8d372d Reported-by: Richard W.M. Jones <rjones@redhat.com> Signed-off-by: Eric Blake <eblake@redhat.com> Message-Id: <20190329042750.14704-3-eblake@redhat.com> Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Tested-by: Richard W.M. Jones <rjones@redhat.com>
2019-02-25block: Purify .bdrv_refresh_filename()Max Reitz1-22/+1
Currently, BlockDriver.bdrv_refresh_filename() is supposed to both refresh the filename (BDS.exact_filename) and set BDS.full_open_options. Now that we have generic code in the central bdrv_refresh_filename() for creating BDS.full_open_options, we can drop the latter part from all BlockDriver.bdrv_refresh_filename() implementations. This also means that we can drop all of the existing default code for this from the global bdrv_refresh_filename() itself. Furthermore, we now have to call BlockDriver.bdrv_refresh_filename() after having set BDS.full_open_options, because the block driver's implementation should now be allowed to depend on BDS.full_open_options being set correctly. Finally, with this patch we can drop the @options parameter from BlockDriver.bdrv_refresh_filename(); also, add a comment on this function's purpose in block/block_int.h while touching its interface. This completely obsoletes blklogwrite's implementation of .bdrv_refresh_filename(). Signed-off-by: Max Reitz <mreitz@redhat.com> Message-id: 20190201192935.18394-25-mreitz@redhat.com Signed-off-by: Max Reitz <mreitz@redhat.com>
2019-02-25block: Add strong_runtime_opts to BlockDriverMax Reitz1-0/+14
This new field can be set by block drivers to list the runtime options they accept that may influence the contents of the respective BDS. As of a follow-up patch, this list will be used by the common bdrv_refresh_filename() implementation to decide which options to put into BDS.full_open_options (and consequently whether a JSON filename has to be created), thus freeing the drivers of having to implement that logic themselves. Additionally, this patch adds the field to all of the block drivers that need it and sets it accordingly. Signed-off-by: Max Reitz <mreitz@redhat.com> Reviewed-by: Alberto Garcia <berto@igalia.com> Message-id: 20190201192935.18394-22-mreitz@redhat.com Signed-off-by: Max Reitz <mreitz@redhat.com>
2019-02-25block/nbd: Make bdrv_dirname() return NULLMax Reitz1-0/+13
The generic bdrv_dirname() implementation would be able to generate some form of directory name for many NBD nodes, but it would be always wrong. Therefore, we have to explicitly make it an error (until NBD has some form of specification for export paths, if it ever will). Signed-off-by: Max Reitz <mreitz@redhat.com> Reviewed-by: Alberto Garcia <berto@igalia.com> Reviewed-by: Eric Blake <eblake@redhat.com> Message-id: 20190201192935.18394-18-mreitz@redhat.com Signed-off-by: Max Reitz <mreitz@redhat.com>
2019-02-04block/nbd: move connection code from block/nbd to block/nbd-clientVladimir Sementsov-Ogievskiy1-38/+2
Keep all connection code in one file, to be able to implement reconnect in further patches. Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Message-Id: <20190201130138.94525-3-vsementsov@virtuozzo.com> Reviewed-by: Eric Blake <eblake@redhat.com> [eblake: format tweak] Signed-off-by: Eric Blake <eblake@redhat.com>
2018-07-28qstring: Move qstring_from_substr()'s @end one to the rightMarkus Armbruster1-1/+1
qstring_from_substr() takes the index of the substring's first and last character. qstring_from_substr(s, 0, SIZE_MAX) denotes an empty substring. Awkward. Shift the end index one to the right. This simplifies both qstring_from_substr() and its callers. Signed-off-by: Markus Armbruster <armbru@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com> Message-Id: <20180727062204.10401-3-armbru@redhat.com>
2018-07-02nbd/client: Add x-dirty-bitmap to query bitmap from serverEric Blake1-2/+8
In order to test that the NBD server is properly advertising dirty bitmaps, we need a bare minimum client that can request and read the context. Since feature freeze for 3.0 is imminent, this is the smallest workable patch, which replaces the qemu block status report with the results of the NBD server's dirty bitmap (making it very easy to use 'qemu-img map --output=json' to learn where the dirty portions are). Note that the NBD protocol defines a dirty section with the same bit but opposite sense that normal "base:allocation" uses to report an allocated section; so in qemu-img map output, "data":true corresponds to clean, "data":false corresponds to dirty. A more complete solution that allows dirty bitmaps to be queried at the same time as normal block status will be required before this addition can lose the x- prefix. Until then, the fact that this replaces normal status with dirty status means actions like 'qemu-img convert' will likely misbehave due to treating dirty regions of the file as if they are unallocated. The next patch adds an iotest to exercise this new code. Signed-off-by: Eric Blake <eblake@redhat.com> Message-Id: <20180702191458.28741-2-eblake@redhat.com>
2018-06-15block: Factor out qobject_input_visitor_new_flat_confused()Markus Armbruster1-5/+2
Signed-off-by: Markus Armbruster <armbru@redhat.com> Reviewed-by: Kevin Wolf <kwolf@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2018-06-15block: Fix -drive for certain non-string scalarsMarkus Armbruster1-10/+2
The previous commit fixed -blockdev breakage due to misuse of the qobject input visitor's keyval flavor in bdrv_file_open(). The commit message explain why using the plain flavor would be just as wrong; it would break -drive. Turns out we break it in three places: nbd_open(), sd_open() and ssh_file_open(). They are even marked FIXME. Example breakage: $ qemu-system-x86 -drive node-name=n1,driver=nbd,server.type=inet,server.host=localhost,server.port=1234,server.numeric=off qemu-system-x86: -drive node-name=n1,driver=nbd,server.type=inet,server.host=localhost,server.port=1234,server.numeric=off: Invalid parameter type for 'numeric', expected: boolean Fix it the same way: replace qdict_crumple() by qdict_crumple_for_keyval_qiv(), and switch from plain to the keyval flavor. Signed-off-by: Markus Armbruster <armbru@redhat.com> Reviewed-by: Kevin Wolf <kwolf@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2018-06-15block: Add block-specific QDict headerMax Reitz1-0/+1
There are numerous QDict functions that have been introduced for and are used only by the block layer. Move their declarations into an own header file to reflect that. While qdict_extract_subqdict() is in fact used outside of the block layer (in util/qemu-config.c), it is still a function related very closely to how the block layer works with nested QDicts, namely by sometimes flattening them. Therefore, its declaration is put into this header as well and util/qemu-config.c includes it with a comment stating exactly which function it needs. Suggested-by: Markus Armbruster <armbru@redhat.com> Signed-off-by: Max Reitz <mreitz@redhat.com> Message-Id: <20180509165530.29561-7-mreitz@redhat.com> [Copyright note tweaked, superfluous includes dropped] Signed-off-by: Markus Armbruster <armbru@redhat.com> Reviewed-by: Kevin Wolf <kwolf@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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