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2021-01-27block: Separate blk_is_writable() and blk_supports_write_perm()Kevin Wolf1-3/+16
Currently, blk_is_read_only() tells whether a given BlockBackend can only be used in read-only mode because its root node is read-only. Some callers actually try to answer a slightly different question: Is the BlockBackend configured to be writable, by taking write permissions on the root node? This can differ, for example, for CD-ROM devices which don't take write permissions, but may be backed by a writable image file. scsi-cd allows write requests to the drive if blk_is_read_only() returns false. However, the write request will immediately run into an assertion failure because the write permission is missing. This patch introduces separate functions for both questions. blk_supports_write_perm() answers the question whether the block node/image file can support writable devices, whereas blk_is_writable() tells whether the BlockBackend is currently configured to be writable. All calls of blk_is_read_only() are converted to one of the two new functions. Fixes: https://bugs.launchpad.net/bugs/1906693 Cc: qemu-stable@nongnu.org Signed-off-by: Kevin Wolf <kwolf@redhat.com> Message-Id: <20210118123448.307825-2-kwolf@redhat.com> Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com> Reviewed-by: Max Reitz <mreitz@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2020-09-23qemu/atomic.h: rename atomic_ to qatomic_Stefan Hajnoczi1-7/+8
clang's C11 atomic_fetch_*() functions only take a C11 atomic type pointer argument. QEMU uses direct types (int, etc) and this causes a compiler error when a QEMU code calls these functions in a source file that also included <stdatomic.h> via a system header file: $ CC=clang CXX=clang++ ./configure ... && make ../util/async.c:79:17: error: address argument to atomic operation must be a pointer to _Atomic type ('unsigned int *' invalid) Avoid using atomic_*() names in QEMU's atomic.h since that namespace is used by <stdatomic.h>. Prefix QEMU's APIs with 'q' so that atomic.h and <stdatomic.h> can co-exist. I checked /usr/include on my machine and searched GitHub for existing "qatomic_" users but there seem to be none. This patch was generated using: $ git grep -h -o '\<atomic\(64\)\?_[a-z0-9_]\+' include/qemu/atomic.h | \ sort -u >/tmp/changed_identifiers $ for identifier in $(</tmp/changed_identifiers); do sed -i "s%\<$identifier\>%q$identifier%g" \ $(git grep -I -l "\<$identifier\>") done I manually fixed line-wrap issues and misaligned rST tables. Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com> Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com> Acked-by: Paolo Bonzini <pbonzini@redhat.com> Message-Id: <20200923105646.47864-1-stefanha@redhat.com>
2020-09-07commit: Deal with filtersMax Reitz1-2/+5
This includes some permission limiting (for example, we only need to take the RESIZE permission if the base is smaller than the top). Signed-off-by: Max Reitz <mreitz@redhat.com>
2020-07-21block: fix bdrv_aio_cancel() for ENOMEDIUM requestsStefan Hajnoczi1-0/+8
bdrv_aio_cancel() calls aio_poll() on the AioContext for the given I/O request until it has completed. ENOMEDIUM requests are special because there is no BlockDriverState when the drive has no medium! Define a .get_aio_context() function for BlkAioEmAIOCB requests so that bdrv_aio_cancel() can find the AioContext where the completion BH is pending. Without this function bdrv_aio_cancel() aborts on ENOMEDIUM requests! libFuzzer triggered the following assertion: cat << EOF | qemu-system-i386 -M pc-q35-5.0 \ -nographic -monitor none -serial none \ -qtest stdio -trace ide\* outl 0xcf8 0x8000fa24 outl 0xcfc 0xe106c000 outl 0xcf8 0x8000fa04 outw 0xcfc 0x7 outl 0xcf8 0x8000fb20 write 0x0 0x3 0x2780e7 write 0xe106c22c 0xd 0x1130c218021130c218021130c2 write 0xe106c218 0x15 0x110010110010110010110010110010110010110010 EOF ide_exec_cmd IDE exec cmd: bus 0x56170a77a2b8; state 0x56170a77a340; cmd 0xe7 ide_reset IDEstate 0x56170a77a340 Aborted (core dumped) (gdb) bt #1 0x00007ffff4f93895 in abort () at /lib64/libc.so.6 #2 0x0000555555dc6c00 in bdrv_aio_cancel (acb=0x555556765550) at block/io.c:2745 #3 0x0000555555dac202 in blk_aio_cancel (acb=0x555556765550) at block/block-backend.c:1546 #4 0x0000555555b1bd74 in ide_reset (s=0x555557213340) at hw/ide/core.c:1318 #5 0x0000555555b1e3a1 in ide_bus_reset (bus=0x5555572132b8) at hw/ide/core.c:2422 #6 0x0000555555b2aa27 in ahci_reset_port (s=0x55555720eb50, port=2) at hw/ide/ahci.c:650 #7 0x0000555555b29fd7 in ahci_port_write (s=0x55555720eb50, port=2, offset=44, val=16) at hw/ide/ahci.c:360 #8 0x0000555555b2a564 in ahci_mem_write (opaque=0x55555720eb50, addr=556, val=16, size=1) at hw/ide/ahci.c:513 #9 0x000055555598415b in memory_region_write_accessor (mr=0x55555720eb80, addr=556, value=0x7fffffffb838, size=1, shift=0, mask=255, attrs=...) at softmmu/memory.c:483 Looking at bdrv_aio_cancel: 2728 /* async I/Os */ 2729 2730 void bdrv_aio_cancel(BlockAIOCB *acb) 2731 { 2732 qemu_aio_ref(acb); 2733 bdrv_aio_cancel_async(acb); 2734 while (acb->refcnt > 1) { 2735 if (acb->aiocb_info->get_aio_context) { 2736 aio_poll(acb->aiocb_info->get_aio_context(acb), true); 2737 } else if (acb->bs) { 2738 /* qemu_aio_ref and qemu_aio_unref are not thread-safe, so 2739 * assert that we're not using an I/O thread. Thread-safe 2740 * code should use bdrv_aio_cancel_async exclusively. 2741 */ 2742 assert(bdrv_get_aio_context(acb->bs) == qemu_get_aio_context()); 2743 aio_poll(bdrv_get_aio_context(acb->bs), true); 2744 } else { 2745 abort(); <=============== 2746 } 2747 } 2748 qemu_aio_unref(acb); 2749 } Fixes: 02c50efe08736116048d5fc355043080f4d5859c ("block: Add bdrv_aio_cancel_async") Reported-by: Alexander Bulekov <alxndr@bu.edu> Buglink: https://bugs.launchpad.net/qemu/+bug/1878255 Originally-by: Philippe Mathieu-Daudé <f4bug@amsat.org> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com> Message-Id: <20200720100141.129739-1-stefanha@redhat.com> Signed-off-by: Max Reitz <mreitz@redhat.com>
2020-07-14block: Avoid stale pointer dereference in blk_get_aio_context()Greg Kurz1-1/+3
It is possible for blk_remove_bs() to race with blk_drain_all(), causing the latter to dereference a stale blk->root pointer: blk_remove_bs(blk) bdrv_root_unref_child(blk->root) child_bs = blk->root->bs bdrv_detach_child(blk->root) ... g_free(blk->root) <============== blk->root becomes stale bdrv_unref(child_bs) <============ yield at some point A blk_drain_all() can be triggered by some guest action in the meantime, eg. on POWER, SLOF might disable bus mastering on a virtio-scsi-pci device: virtio_write_config() virtio_pci_stop_ioeventfd() virtio_bus_stop_ioeventfd() virtio_scsi_dataplane_stop() blk_drain_all() blk_get_aio_context() bs = blk->root ? blk->root->bs : NULL ^^^^^^^^^ stale Then, depending on one's luck, QEMU either crashes with SEGV or hits the assertion in blk_get_aio_context(). blk->root is set by blk_insert_bs() which calls bdrv_root_attach_child() first. The blk_remove_bs() function should rollback the changes made by blk_insert_bs() in the opposite order (or it should be documented somewhere why this isn't the case). Clear blk->root before calling bdrv_root_unref_child() in blk_remove_bs(). Signed-off-by: Greg Kurz <groug@kaod.org> Message-Id: <159430264541.389456.11925072456012783045.stgit@bahia.lan> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2020-05-18block: Pass BdrvChildRole in remaining casesMax Reitz1-4/+7
These calls have no real use for the child role yet, but it will not harm to give one. Notably, the bdrv_root_attach_child() call in blockjob.c is left unmodified because there is not much the generic BlockJob object wants from its children. Signed-off-by: Max Reitz <mreitz@redhat.com> Message-Id: <20200513110544.176672-34-mreitz@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2020-05-18block: Pass parent_is_format to .inherit_options()Max Reitz1-1/+1
We plan to unify the generic .inherit_options() functions. The resulting common function will need to decide whether to force-enable format probing, force-disable it, or leave it as-is. To make this decision, it will need to know whether the parent node is a format node or not (because we never want format probing if the parent is a format node already (except for the backing chain)). Signed-off-by: Max Reitz <mreitz@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com> Message-Id: <20200513110544.176672-9-mreitz@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2020-05-18block: Pass BdrvChildRole to .inherit_options()Max Reitz1-1/+2
For now, all callers (effectively) pass 0 and no callee evaluates thie value. Later patches will change both. Signed-off-by: Max Reitz <mreitz@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com> Message-Id: <20200513110544.176672-8-mreitz@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2020-05-18block: Add BdrvChildRole to BdrvChildMax Reitz1-2/+2
For now, it is always set to 0. Later patches in this series will ensure that all callers pass an appropriate combination of flags. Signed-off-by: Max Reitz <mreitz@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com> Message-Id: <20200513110544.176672-6-mreitz@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2020-05-18block: Rename BdrvChildRole to BdrvChildClassMax Reitz1-3/+3
This structure nearly only contains parent callbacks for child state changes. It cannot really reflect a child's role, because different roles may overlap (as we will see when real roles are introduced), and because parents can have custom callbacks even when the child fulfills a standard role. Signed-off-by: Max Reitz <mreitz@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com> Reviewed-by: Alberto Garcia <berto@igalia.com> Message-Id: <20200513110544.176672-4-mreitz@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2020-05-18block: Add blk_make_empty()Max Reitz1-0/+10
Two callers of BlockDriver.bdrv_make_empty() remain that should not call this method directly. Both do not have access to a BdrvChild, but they can use a BlockBackend, so we add this function that lets them use it. Signed-off-by: Max Reitz <mreitz@redhat.com> Message-Id: <20200429141126.85159-4-mreitz@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2020-05-05block: Add blk_new_with_bs() helperEric Blake1-0/+23
There are several callers that need to create a new block backend from an existing BDS; make the task slightly easier with a common helper routine. Suggested-by: Max Reitz <mreitz@redhat.com> Signed-off-by: Eric Blake <eblake@redhat.com> Message-Id: <20200424190903.522087-2-eblake@redhat.com> [mreitz: Set @ret only in error paths, see https://lists.nongnu.org/archive/html/qemu-block/2020-04/msg01216.html] Signed-off-by: Max Reitz <mreitz@redhat.com> Message-Id: <20200428192648.749066-2-eblake@redhat.com> Signed-off-by: Max Reitz <mreitz@redhat.com>
2020-04-30block-backend: Add flags to blk_truncate()Kevin Wolf1-2/+2
Now that node level interface bdrv_truncate() supports passing request flags to the block driver, expose this on the BlockBackend level, too. Signed-off-by: Kevin Wolf <kwolf@redhat.com> Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Reviewed-by: Alberto Garcia <berto@igalia.com> Reviewed-by: Max Reitz <mreitz@redhat.com> Message-Id: <20200424125448.63318-4-kwolf@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2020-04-30block: Add flags to bdrv(_co)_truncate()Kevin Wolf1-1/+1
Now that block drivers can support flags for .bdrv_co_truncate, expose the parameter in the node level interfaces bdrv_co_truncate() and bdrv_truncate(). Signed-off-by: Kevin Wolf <kwolf@redhat.com> Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Reviewed-by: Alberto Garcia <berto@igalia.com> Reviewed-by: Max Reitz <mreitz@redhat.com> Message-Id: <20200424125448.63318-3-kwolf@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2020-04-07block: Fix blk->in_flight during blk_wait_while_drained()Kevin Wolf1-12/+5
Waiting in blk_wait_while_drained() while blk->in_flight is increased for the current request is wrong because it will cause the drain operation to deadlock. This patch makes sure that blk_wait_while_drained() is called with blk->in_flight increased exactly once for the current request, and that it temporarily decreases the counter while it waits. Fixes: cf3129323f900ef5ddbccbe86e4fa801e88c566e Signed-off-by: Kevin Wolf <kwolf@redhat.com> Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Reviewed-by: Max Reitz <mreitz@redhat.com> Message-Id: <20200407121259.21350-4-kwolf@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2020-04-07block: Increase BB.in_flight for coroutine and sync interfacesKevin Wolf1-23/+80
External callers of blk_co_*() and of the synchronous blk_*() functions don't currently increase the BlockBackend.in_flight counter, but calls from blk_aio_*() do, so there is an inconsistency whether the counter has been increased or not. This patch moves the actual operations to static functions that can later know they will always be called with in_flight increased exactly once, even for external callers using the blk_co_*() coroutine interfaces. If the public blk_co_*() interface is unused, remove it. Signed-off-by: Kevin Wolf <kwolf@redhat.com> Message-Id: <20200407121259.21350-3-kwolf@redhat.com> Reviewed-by: Max Reitz <mreitz@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2020-04-07block-backend: Reorder flush/pdiscard function definitionsKevin Wolf1-46/+46
Move all variants of the flush/pdiscard functions to a single place and put the blk_co_*() version first because it is called by all other variants (and will become static in the next patch). Signed-off-by: Kevin Wolf <kwolf@redhat.com> Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Reviewed-by: Max Reitz <mreitz@redhat.com> Message-Id: <20200407121259.21350-2-kwolf@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2019-10-28block: Add @exact parameter to bdrv_co_truncate()Max Reitz1-3/+3
We have two drivers (iscsi and file-posix) that (in some cases) return success from their .bdrv_co_truncate() implementation if the block device is larger than the requested offset, but cannot be shrunk. Some callers do not want that behavior, so this patch adds a new parameter that they can use to turn off that behavior. This patch just adds the parameter and lets the block/io.c and block/block-backend.c functions pass it around. All other callers always pass false and none of the implementations evaluate it, so that this patch does not change existing behavior. Future patches take care of that. Suggested-by: Maxim Levitsky <mlevitsk@redhat.com> Signed-off-by: Max Reitz <mreitz@redhat.com> Message-id: 20190918095144.955-5-mreitz@redhat.com Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com> Signed-off-by: Max Reitz <mreitz@redhat.com>
2019-10-28block/block-backend: add blk_co_pwritev_partVladimir Sementsov-Ogievskiy1-4/+13
Add blk write function with qiov_offset parameter. It's needed for the following commit. Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Reviewed-by: Max Reitz <mreitz@redhat.com> Message-id: 20191011090711.19940-4-vsementsov@virtuozzo.com Signed-off-by: Max Reitz <mreitz@redhat.com>
2019-10-14replay: add BH oneshot event for block layerPavel Dovgalyuk1-3/+6
Replay is capable of recording normal BH events, but sometimes there are single use callbacks scheduled with aio_bh_schedule_oneshot function. This patch enables recording and replaying such callbacks. Block layer uses these events for calling the completion function. Replaying these calls makes the execution deterministic. Signed-off-by: Pavel Dovgalyuk <Pavel.Dovgaluk@ispras.ru> Acked-by: Kevin Wolf <kwolf@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2019-08-16Merge remote-tracking branch 'remotes/kevin/tags/for-upstream' into stagingPeter Maydell1-19/+50
Block layer patches: - file-posix: Fix O_DIRECT alignment detection - Fixes for concurrent block jobs - block-backend: Queue requests while drained (fix IDE vs. job crashes) - qemu-img convert: Deprecate using -n and -o together - iotests: Migration tests with filter nodes - iotests: More media change tests # gpg: Signature made Fri 16 Aug 2019 10:29:18 BST # gpg: using RSA key 7F09B272C88F2FD6 # gpg: Good signature from "Kevin Wolf <kwolf@redhat.com>" [full] # Primary key fingerprint: DC3D EB15 9A9A F95D 3D74 56FE 7F09 B272 C88F 2FD6 * remotes/kevin/tags/for-upstream: file-posix: Handle undetectable alignment qemu-img convert: Deprecate using -n and -o together block-backend: Queue requests while drained mirror: Keep mirror_top_bs drained after dropping permissions block: Remove blk_pread_unthrottled() iotests: Add test for concurrent stream/commit tests: Test mid-drain bdrv_replace_child_noperm() tests: Test polling in bdrv_drop_intermediate() block: Reduce (un)drains when replacing a child block: Keep subtree drained in drop_intermediate block: Simplify bdrv_filter_default_perms() iotests: Test migration with all kinds of filter nodes iotests: Move migration helpers to iotests.py iotests/118: Add -blockdev based tests iotests/118: Create test classes dynamically iotests/118: Test media change for scsi-cd Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
2019-08-16sysemu: Split sysemu/runstate.h off sysemu/sysemu.hMarkus Armbruster1-1/+1
sysemu/sysemu.h is a rather unfocused dumping ground for stuff related to the system-emulator. Evidence: * It's included widely: in my "build everything" tree, changing sysemu/sysemu.h still triggers a recompile of some 1100 out of 6600 objects (not counting tests and objects that don't depend on qemu/osdep.h, down from 5400 due to the previous two commits). * It pulls in more than a dozen additional headers. Split stuff related to run state management into its own header sysemu/runstate.h. Touching sysemu/sysemu.h now recompiles some 850 objects. qemu/uuid.h also drops from 1100 to 850, and qapi/qapi-types-run-state.h from 4400 to 4200. Touching new sysemu/runstate.h recompiles some 500 objects. Since I'm touching MAINTAINERS to add sysemu/runstate.h anyway, also add qemu/main-loop.h. Suggested-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Markus Armbruster <armbru@redhat.com> Message-Id: <20190812052359.30071-30-armbru@redhat.com> Reviewed-by: Alex Bennée <alex.bennee@linaro.org> [Unbreak OS-X build]
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>
2019-08-16trace: Do not include qom/cpu.h into generated trace.hMarkus Armbruster1-0/+1
docs/devel/tracing.txt explains "since many source files include trace.h, [the generated trace.h use] a minimum of types and other header files included to keep the namespace clean and compile times and dependencies down." Commit 4815185902 "trace: Add per-vCPU tracing states for events with the 'vcpu' property" made them all include qom/cpu.h via control-internal.h. qom/cpu.h in turn includes about thirty headers. Ouch. Per-vCPU tracing is currently not supported in sub-directories' trace-events. In other words, qom/cpu.h can only be used in trace-root.h, not in any trace.h. Split trace/control-vcpu.h off trace/control.h and trace/control-internal.h. Have the generated trace.h include trace/control.h (which no longer includes qom/cpu.h), and trace-root.h include trace/control-vcpu.h (which includes it). The resulting improvement is a bit disappointing: in my "build everything" tree, some 1100 out of 6600 objects (not counting tests and objects that don't depend on qemu/osdep.h) depend on a trace.h, and about 600 of them no longer depend on qom/cpu.h. But more than 1300 others depend on trace-root.h. More work is clearly needed. Left for another day. Cc: Stefan Hajnoczi <stefanha@redhat.com> Signed-off-by: Markus Armbruster <armbru@redhat.com> Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com> Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com> Tested-by: Philippe Mathieu-Daudé <philmd@redhat.com> Message-Id: <20190812052359.30071-8-armbru@redhat.com>
2019-08-16block-backend: Queue requests while drainedKevin Wolf1-3/+50
This fixes devices like IDE that can still start new requests from I/O handlers in the CPU thread while the block backend is drained. The basic assumption is that in a drain section, no new requests should be allowed through a BlockBackend (blk_drained_begin/end don't exist, we get drain sections only on the node level). However, there are two special cases where requests should not be queued: 1. Block jobs: We already make sure that block jobs are paused in a drain section, so they won't start new requests. However, if the drain_begin is called on the job's BlockBackend first, it can happen that we deadlock because the job stays busy until it reaches a pause point - which it can't if its requests aren't processed any more. The proper solution here would be to make all requests through the job's filter node instead of using a BlockBackend. For now, just disabling request queuing on the job BlockBackend is simpler. 2. In test cases where making requests through bdrv_* would be cumbersome because we'd need a BdrvChild. As we already got the functionality to disable request queuing from 1., use it in tests, too, for convenience. Signed-off-by: Kevin Wolf <kwolf@redhat.com> Reviewed-by: Max Reitz <mreitz@redhat.com>
2019-08-16block: Remove blk_pread_unthrottled()Kevin Wolf1-16/+0
The functionality offered by blk_pread_unthrottled() goes back to commit 498e386c584. Then, we couldn't perform I/O throttling with synchronous requests because timers wouldn't be executed in polling loops. So the commit automatically disabled I/O throttling as soon as a synchronous request was issued. However, for geometry detection during disk initialisation, we always used (and still use) synchronous requests even if guest requests use AIO later. Geometry detection was not wanted to disable I/O throttling, so bdrv_pread_unthrottled() was introduced which disabled throttling only temporarily. All of this isn't necessary any more because we do run timers in polling loop and even synchronous requests are now using coroutine infrastructure internally. For this reason, commit 90c78624f already removed the automatic disabling of I/O throttling. It's time to get rid of the workaround for the removed code, and its abuse of blk_root_drained_begin()/end(), as well. Signed-off-by: Kevin Wolf <kwolf@redhat.com> Reviewed-by: Max Reitz <mreitz@redhat.com>
2019-07-19block: Do not poll in bdrv_do_drained_end()Max Reitz1-3/+3
We should never poll anywhere in bdrv_do_drained_end() (including its recursive callees like bdrv_drain_invoke()), because it does not cope well with graph changes. In fact, it has been written based on the postulation that no graph changes will happen in it. Instead, the callers that want to poll must poll, i.e. all currently globally available wrappers: bdrv_drained_end(), bdrv_subtree_drained_end(), bdrv_unapply_subtree_drain(), and bdrv_drain_all_end(). Graph changes there do not matter. They can poll simply by passing a pointer to a drained_end_counter and wait until it reaches 0. This patch also adds a non-polling global wrapper for bdrv_do_drained_end() that takes a drained_end_counter pointer. We need such a variant because now no function called anywhere from bdrv_do_drained_end() must poll. This includes BdrvChildRole.drained_end(), which already must not poll according to its interface documentation, but bdrv_child_cb_drained_end() just violates that by invoking bdrv_drained_end() (which does poll). Therefore, BdrvChildRole.drained_end() must take a *drained_end_counter parameter, which bdrv_child_cb_drained_end() can pass on to the new bdrv_drained_end_no_poll() function. Note that we now have a pattern of all drained_end-related functions either polling or receiving a *drained_end_counter to let the caller poll based on that. A problem with a single poll loop is that when the drained section in bdrv_set_aio_context_ignore() ends, some nodes in the subgraph may be in the old contexts, while others are in the new context already. To let the collective poll in bdrv_drained_end() work correctly, we must not hold a lock to the old context, so that the old context can make progress in case it is different from the current context. (In the process, remove the comment saying that the current context is always the old context, because it is wrong.) In all other places, all nodes in a subtree must be in the same context, so we can just poll that. The exception of course is bdrv_drain_all_end(), but that always runs in the main context, so we can just poll NULL (like bdrv_drain_all_begin() does). Signed-off-by: Max Reitz <mreitz@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2019-06-18block/block-backend: blk_iostatus_reset: drop usage of bs->jobVladimir Sementsov-Ogievskiy1-4/+0
We are going to remove bs->job pointer. Drop it's usage in blk_iostatus_reset. blk_iostatus_reset() has only two callers: 1. blk_attach_dev(). This doesn't have anything to do with jobs and attaching a new guest device won't solve any problem the job encountered, so no reason to reset the iostatus for the job. 2. qmp_cont(). This resets the iostatus for everything. We can just call block_job_iostatus_reset() for all block jobs instead of going through BlockBackend. Suggested-by: Kevin Wolf <kwolf@redhat.com> Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2019-06-04block: Adjust AioContexts when attaching nodesKevin Wolf1-5/+4
So far, we only made sure that updating the AioContext of a node affected the whole subtree. However, if a node is newly attached to a new parent, we also need to make sure that both the subtree of the node and the parent are in the same AioContext. This tries to move the new child node to the parent AioContext and returns an error if this isn't possible. BlockBackends now actually apply their AioContext to their root node. Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2019-06-04block: Add BlockBackend.ctxKevin Wolf1-3/+15
This adds a new parameter to blk_new() which requires its callers to declare from which AioContext this BlockBackend is going to be used (or the locks of which AioContext need to be taken anyway). The given context is only stored and kept up to date when changing AioContexts. Actually applying the stored AioContext to the root node is saved for another commit. Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2019-06-04block: Add Error to blk_set_aio_context()Kevin Wolf1-10/+16
Add an Error parameter to blk_set_aio_context() and use bdrv_child_try_set_aio_context() internally to check whether all involved nodes can actually support the AioContext switch. Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2019-05-28block: Make bdrv_root_attach_child() unref child_bs on failureAlberto Garcia1-2/+1
A consequence of the previous patch is that bdrv_attach_child() transfers the reference to child_bs from the caller to parent_bs, which will drop it on bdrv_close() or when someone calls bdrv_unref_child(). But this only happens when bdrv_attach_child() succeeds. If it fails then the caller is responsible for dropping the reference to child_bs. This patch makes bdrv_attach_child() take the reference also when there is an error, freeing the caller for having to do it. A similar situation happens with bdrv_root_attach_child(), so the changes on this patch affect both functions. Signed-off-by: Alberto Garcia <berto@igalia.com> Message-id: 20dfb3d9ccec559cdd1a9690146abad5d204a186.1557754872.git.berto@igalia.com [mreitz: Removed now superfluous BdrvChild * variable in bdrv_open_child()] Signed-off-by: Max Reitz <mreitz@redhat.com>
2019-05-20block: Add blk_set_allow_aio_context_change()Kevin Wolf1-0/+10
Some users (like block jobs) can tolerate an AioContext change for their BlockBackend. Add a function that tells the BlockBackend that it can allow changes. Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2019-05-20block: Implement .(can_)set_aio_ctx for BlockBackendKevin Wolf1-2/+43
bdrv_try_set_aio_context() currently fails if a BlockBackend is attached to a node because it doesn't implement the BdrvChildRole callbacks for AioContext management. We can allow changing the AioContext of monitor-owned BlockBackends as long as no device is attached to them. When setting the AioContext of the root node of a BlockBackend, we now need to pass blk->root as an ignored child because we don't want the root node to recursively call back into BlockBackend and execute blk_do_set_aio_context() a second time. Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2019-04-01block: Add bdrv_get_request_alignment()Eric Blake1-0/+7
The next patch needs access to a device's minimum permitted alignment, since NBD wants to advertise this to clients. Add an accessor function, borrowing from blk_get_max_transfer() for accessing a backend's block limits. Signed-off-by: Eric Blake <eblake@redhat.com> Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Message-Id: <20190329042750.14704-6-eblake@redhat.com>
2019-02-26Merge remote-tracking branch 'remotes/kevin/tags/for-upstream' into stagingPeter Maydell1-2/+2
Block layer patches: - Block graph change fixes (avoid loops, cope with non-tree graphs) - bdrv_set_aio_context() related fixes - HMP snapshot commands: Use only tag, not the ID to identify snapshots - qmeu-img, commit: Error path fixes - block/nvme: Build fix for gcc 9 - MAINTAINERS updates - Fix various issues with bdrv_refresh_filename() - Fix various iotests - Include LUKS overhead in qemu-img measure for qcow2 - A fix for vmdk's image creation interface # gpg: Signature made Mon 25 Feb 2019 14:18:15 GMT # gpg: using RSA key 7F09B272C88F2FD6 # gpg: Good signature from "Kevin Wolf <kwolf@redhat.com>" [full] # Primary key fingerprint: DC3D EB15 9A9A F95D 3D74 56FE 7F09 B272 C88F 2FD6 * remotes/kevin/tags/for-upstream: (71 commits) iotests: Skip 211 on insufficient memory vmdk: false positive of compat6 with hwversion not set iotests: add LUKS payload overhead to 178 qemu-img measure test qcow2: include LUKS payload overhead in qemu-img measure iotests.py: s/_/-/g on keys in qmp_log() iotests: Let 045 be run concurrently iotests: Filter SSH paths iotests.py: Filter filename in any string value iotests.py: Add is_str() iotests: Fix 207 to use QMP filters for qmp_log iotests: Fix 232 for LUKS iotests: Remove superfluous rm from 232 iotests: Fix 237 for Python 2.x iotests: Re-add filename filters iotests: Test json:{} filenames of internal BDSs block: BDS options may lack the "driver" option block/null: Generate filename even with latency-ns block/curl: Implement bdrv_refresh_filename() block/curl: Harmonize option defaults block/nvme: Fix bdrv_refresh_filename() ... Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
2019-02-25block-backend: Make blk_inc/dec_in_flight publicKevin Wolf1-2/+2
For some users of BlockBackends, just increasing the in_flight counter is easier than implementing separate handlers in BlockDevOps. Make the helper functions for this public. Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2019-02-22block/block-backend: use QEMU_IOVEC_INIT_BUFVladimir Sementsov-Ogievskiy1-11/+2
Use new QEMU_IOVEC_INIT_BUF() instead of qemu_iovec_init_external( ... , 1), which simplifies the code. Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Reviewed-by: Eric Blake <eblake@redhat.com> Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com> Message-id: 20190218140926.333779-4-vsementsov@virtuozzo.com Message-Id: <20190218140926.333779-4-vsementsov@virtuozzo.com> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2019-02-01block: Remove blk_attach_dev_legacy() / legacy_dev codeThomas Huth1-45/+9
The last user of blk_attach_dev_legacy() was the code in xen_disk which has recently been reworked. Now there is no user for this legacy function anymore. Thus we can finally remove all code related to the "legacy_dev" flag, too, and turn the related "void *" in block-backend.c into proper "DeviceState *" to fix some of the remaining TODOs there. Signed-off-by: Thomas Huth <thuth@redhat.com> Reviewed-by: Stefano Garzarella <sgarzare@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2019-02-01block: Fix hangs in synchronous APIs with iothreadsKevin Wolf1-0/+5
In the block layer, synchronous APIs are often implemented by creating a coroutine that calls the asynchronous coroutine-based implementation and then waiting for completion with BDRV_POLL_WHILE(). For this to work with iothreads (more specifically, when the synchronous API is called in a thread that is not the home thread of the block device, so that the coroutine will run in a different thread), we must make sure to call aio_wait_kick() at the end of the operation. Many places are missing this, so that BDRV_POLL_WHILE() keeps hanging even if the condition has long become false. Note that bdrv_dec_in_flight() involves an aio_wait_kick() call. This corresponds to the BDRV_POLL_WHILE() in the drain functions, but it is generally not enough for most other operations because they haven't set the return value in the coroutine entry stub yet. To avoid race conditions there, we need to kick after setting the return value. The race window is small enough that the problem doesn't usually surface in the common path. However, it does surface and causes easily reproducible hangs if the operation can return early before even calling bdrv_inc/dec_in_flight, which many of them do (trivial error or no-op success paths). The bug in bdrv_truncate(), bdrv_check() and bdrv_invalidate_cache() is slightly different: These functions even neglected to schedule the coroutine in the home thread of the node. This avoids the hang, but is obviously wrong, too. Fix those to schedule the coroutine in the right AioContext in addition to adding aio_wait_kick() calls. Cc: qemu-stable@nongnu.org Signed-off-by: Kevin Wolf <kwolf@redhat.com> Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
2019-01-31qapi: add x-debug-query-block-graphVladimir Sementsov-Ogievskiy1-0/+5
Add a new command, returning block nodes (and their users) graph. Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Message-id: 20181221170909.25584-2-vsementsov@virtuozzo.com Signed-off-by: Max Reitz <mreitz@redhat.com>
2018-11-12block: Null pointer dereference in blk_root_get_parent_desc()Liam Merwick1-1/+2
The dev_id returned by the call to blk_get_attached_dev_id() in blk_root_get_parent_desc() can be NULL (an internal call to object_get_canonical_path may have returned NULL). Instead of just checking this case before before dereferencing, adjust blk_get_attached_dev_id() to return the empty string if no object path can be found (similar to the case when blk->dev is NULL and an empty string is returned). Signed-off-by: Liam Merwick <Liam.Merwick@oracle.com> Message-id: 1541453919-25973-3-git-send-email-Liam.Merwick@oracle.com Reviewed-by: Max Reitz <mreitz@redhat.com> Signed-off-by: Max Reitz <mreitz@redhat.com>
2018-11-05block: change some function return type to boolLi Qiang1-4/+4
Signed-off-by: Li Qiang <liq3ea@163.com> Reviewed-by: Alberto Garcia <berto@igalia.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2018-10-01block-backend: Set werror/rerror defaults in blk_new()Kevin Wolf1-0/+3
Currently, the default values for werror and rerror have to be set explicitly with blk_set_on_error() by the callers of blk_new(). The only caller actually doing this is blockdev_init(), which is called for BlockBackends created using -drive. In particular, anonymous BlockBackends created with -device ...,drive=<node-name> didn't get the correct default set and instead defaulted to the integer value 0 (= BLOCKDEV_ON_ERROR_REPORT). This is the intended default for rerror anyway, but the default for werror should be BLOCKDEV_ON_ERROR_ENOSPC. Set the defaults in blk_new() instead so that they apply no matter what way the BlockBackend was created. Cc: qemu-stable@nongnu.org Signed-off-by: Kevin Wolf <kwolf@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com> Reviewed-by: Fam Zheng <famz@redhat.com>
2018-09-25block: Use a single global AioWaitKevin Wolf1-7/+4
When draining a block node, we recurse to its parent and for subtree drains also to its children. A single AIO_WAIT_WHILE() is then used to wait for bdrv_drain_poll() to become true, which depends on all of the nodes we recursed to. However, if the respective child or parent becomes quiescent and calls bdrv_wakeup(), only the AioWait of the child/parent is checked, while AIO_WAIT_WHILE() depends on the AioWait of the original node. Fix this by using a single AioWait for all callers of AIO_WAIT_WHILE(). This may mean that the draining thread gets a few more unnecessary wakeups because an unrelated operation got completed, but we already wake it up when something _could_ have changed rather than only if it has certainly changed. Apart from that, drain is a slow path anyway. In theory it would be possible to use wakeups more selectively and still correctly, but the gains are likely not worth the additional complexity. In fact, this patch is a nice simplification for some places in the code. Signed-off-by: Kevin Wolf <kwolf@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com> Reviewed-by: Max Reitz <mreitz@redhat.com>
2018-09-25block-backend: Decrease in_flight only after callbackKevin Wolf1-1/+1
Request callbacks can do pretty much anything, including operations that will yield from the coroutine (such as draining the backend). In that case, a decreased in_flight would be visible to other code and could lead to a drain completing while the callback hasn't actually completed yet. Note that reordering these operations forbids calling drain directly inside an AIO callback. As Paolo explains, indirectly calling it is okay: - Calling it through a coroutine is okay, because then bdrv_drained_begin() goes through bdrv_co_yield_to_drain() and you have in_flight=2 when bdrv_co_yield_to_drain() yields, then soon in_flight=1 when the aio_co_wake() in the AIO callback completes, then in_flight=0 after the bottom half starts. - Calling it through a bottom half would be okay too, as long as the AIO callback remembers to do inc_in_flight/dec_in_flight just like bdrv_co_yield_to_drain() and bdrv_co_drain_bh_cb() do A few more important cases that come to mind: - A coroutine that yields because of I/O is okay, with a sequence similar to bdrv_co_yield_to_drain(). - A coroutine that yields with no I/O pending will correctly decrease in_flight to zero before yielding. - Calling more AIO from the callback won't overflow the counter just because of mutual recursion, because AIO functions always yield at least once before invoking the callback. Signed-off-by: Kevin Wolf <kwolf@redhat.com> Reviewed-by: Fam Zheng <famz@redhat.com> Reviewed-by: Max Reitz <mreitz@redhat.com> Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
2018-09-25block-backend: Fix potential double blk_delete()Kevin Wolf1-1/+8
blk_unref() first decreases the refcount of the BlockBackend and calls blk_delete() if the refcount reaches zero. Requests can still be in flight at this point, they are only drained during blk_delete(): At this point, arbitrary callbacks can run. If any callback takes a temporary BlockBackend reference, it will first increase the refcount to 1 and then decrease it to 0 again, triggering another blk_delete(). This will cause a use-after-free crash in the outer blk_delete(). Fix it by draining the BlockBackend before decreasing to refcount to 0. Assert in blk_ref() that it never takes the first refcount (which would mean that the BlockBackend is already being deleted). Signed-off-by: Kevin Wolf <kwolf@redhat.com> Reviewed-by: Fam Zheng <famz@redhat.com> Reviewed-by: Max Reitz <mreitz@redhat.com>
2018-09-25block-backend: Add .drained_poll callbackKevin Wolf1-0/+9
A bdrv_drain operation must ensure that all parents are quiesced, this includes BlockBackends. Otherwise, callbacks called by requests that are completed on the BDS layer, but not quite yet on the BlockBackend layer could still create new requests. Signed-off-by: Kevin Wolf <kwolf@redhat.com> Reviewed-by: Fam Zheng <famz@redhat.com> Reviewed-by: Max Reitz <mreitz@redhat.com>
2018-08-28qapi: Drop qapi_event_send_FOO()'s Error ** argumentPeter Xu1-5/+3
The generated qapi_event_send_FOO() take an Error ** argument. They can't actually fail, because all they do with the argument is passing it to functions that can't fail: the QObject output visitor, and the @qmp_emit callback, which is either monitor_qapi_event_queue() or event_test_emit(). Drop the argument, and pass &error_abort to the QObject output visitor and @qmp_emit instead. Suggested-by: Eric Blake <eblake@redhat.com> Suggested-by: Markus Armbruster <armbru@redhat.com> Signed-off-by: Peter Xu <peterx@redhat.com> Message-Id: <20180815133747.25032-4-peterx@redhat.com> Reviewed-by: Markus Armbruster <armbru@redhat.com> [Commit message rewritten, update to qapi-code-gen.txt corrected] Signed-off-by: Markus Armbruster <armbru@redhat.com>
2018-08-15block: Remove deprecated -drive option serialKevin Wolf1-1/+0
This reinstates commit b0083267444a5e0f28391f6c2831a539f878d424, which was temporarily reverted for the 3.0 release so that libvirt gets some extra time to update their command lines. The -drive option serial was deprecated in QEMU 2.10. It's time to remove it. Tests need to be updated to set the serial number with -global instead of using the -drive option. Signed-off-by: Kevin Wolf <kwolf@redhat.com> Reviewed-by: Markus Armbruster <armbru@redhat.com> Reviewed-by: Jeff Cody <jcody@redhat.com>
generated by cgit v1.1 at 2024-09-27 19:31:35 +0000