Merge tag 'for-upstream' of https://repo.or.cz/qemu/kevin into staging

Block layer patches

- aio-posix: Fix race during epoll upgrade
- vhost-user-blk/VDUSE export: Fix a potential deadlock and an

Merge tag 'for-upstream' of https://repo.or.cz/qemu/kevin into staging

Block layer patches

- aio-posix: Fix race during epoll upgrade
- vhost-user-blk/VDUSE export: Fix a potential deadlock and an assertion
failure when the export runs in an iothread
- NBD server: Push pending frames after sending reply to fix performance
especially when used with TLS

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# gpg: Good signature from "Kevin Wolf <kwolf@redhat.com>" [full]
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* tag 'for-upstream' of https://repo.or.cz/qemu/kevin:
block/export: Fix graph locking in blk_get_geometry() call
aio-posix: fix race between epoll upgrade and aio_set_fd_handler()
block/export: only acquire AioContext once for vhost_user_server_stop()
nbd/server: push pending frames after sending reply

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

show more ...

block/export: Fix graph locking in blk_get_geometry() call

blk_get_geometry() eventually calls bdrv_nb_sectors(), which is a
co_wrapper_mixed_bdrv_rdlock. This means that when it is called from
coro

block/export: Fix graph locking in blk_get_geometry() call

blk_get_geometry() eventually calls bdrv_nb_sectors(), which is a
co_wrapper_mixed_bdrv_rdlock. This means that when it is called from
coroutine context, it already assume to have the graph locked.

However, virtio_blk_sect_range_ok() in block/export/virtio-blk-handler.c
(used by vhost-user-blk and VDUSE exports) runs in a coroutine, but
doesn't take the graph lock - blk_*() functions are generally expected
to do that internally. This causes an assertion failure when accessing
an export for the first time if it runs in an iothread.

This is an example of the crash:

$ ./storage-daemon/qemu-storage-daemon --object iothread,id=th0 --blockdev file,filename=/home/kwolf/images/hd.img,node-name=disk --export vhost-user-blk,addr.type=unix,addr.path=/tmp/vhost.sock,node-name=disk,id=exp0,iothread=th0
qemu-storage-daemon: ../block/graph-lock.c:268: void assert_bdrv_graph_readable(void): Assertion `qemu_in_main_thread() || reader_count()' failed.

(gdb) bt
#0 0x00007ffff6eafe5c in __pthread_kill_implementation () from /lib64/libc.so.6
#1 0x00007ffff6e5fa76 in raise () from /lib64/libc.so.6
#2 0x00007ffff6e497fc in abort () from /lib64/libc.so.6
#3 0x00007ffff6e4971b in __assert_fail_base.cold () from /lib64/libc.so.6
#4 0x00007ffff6e58656 in __assert_fail () from /lib64/libc.so.6
#5 0x00005555556337a3 in assert_bdrv_graph_readable () at ../block/graph-lock.c:268
#6 0x00005555555fd5a2 in bdrv_co_nb_sectors (bs=0x5555564c5ef0) at ../block.c:5847
#7 0x00005555555ee949 in bdrv_nb_sectors (bs=0x5555564c5ef0) at block/block-gen.c:256
#8 0x00005555555fd6b9 in bdrv_get_geometry (bs=0x5555564c5ef0, nb_sectors_ptr=0x7fffef7fedd0) at ../block.c:5884
#9 0x000055555562ad6d in blk_get_geometry (blk=0x5555564cb200, nb_sectors_ptr=0x7fffef7fedd0) at ../block/block-backend.c:1624
#10 0x00005555555ddb74 in virtio_blk_sect_range_ok (blk=0x5555564cb200, block_size=512, sector=0, size=512) at ../block/export/virtio-blk-handler.c:44
#11 0x00005555555dd80d in virtio_blk_process_req (handler=0x5555564cbb98, in_iov=0x7fffe8003830, out_iov=0x7fffe8003860, in_num=1, out_num=0) at ../block/export/virtio-blk-handler.c:189
#12 0x00005555555dd546 in vu_blk_virtio_process_req (opaque=0x7fffe8003800) at ../block/export/vhost-user-blk-server.c:66
#13 0x00005555557bf4a1 in coroutine_trampoline (i0=-402635264, i1=32767) at ../util/coroutine-ucontext.c:177
#14 0x00007ffff6e75c20 in ?? () from /lib64/libc.so.6
#15 0x00007fffefffa870 in ?? ()
#16 0x0000000000000000 in ?? ()

Fix this by creating a new blk_co_get_geometry() that takes the lock,
and changing blk_get_geometry() to be a co_wrapper_mixed around it.

To make the resulting code cleaner, virtio-blk-handler.c can directly
call the coroutine version now (though that wouldn't be necessary for
fixing the bug, taking the lock in blk_co_get_geometry() is what fixes
it).

Fixes: 8ab8140a04cf771d63e9754d6ba6c1e676bfe507
Reported-by: Lukáš Doktor <ldoktor@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Message-Id: <20230327113959.60071-1-kwolf@redhat.com>
Reviewed-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

show more ...

Merge tag 'for-upstream' of git://repo.or.cz/qemu/kevin into staging

Block layer patches

- Add vduse-blk export
- Dirty bitmaps: Fix and improve bitmap merge
- gluster: correctly set max_pdiscard
-

Merge tag 'for-upstream' of git://repo.or.cz/qemu/kevin into staging

Block layer patches

- Add vduse-blk export
- Dirty bitmaps: Fix and improve bitmap merge
- gluster: correctly set max_pdiscard
- rbd: report a better error when namespace does not exist
- aio_wait_kick: add missing memory barrier
- Code cleanups

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# gpg: Good signature from "Kevin Wolf <kwolf@redhat.com>" [full]

* tag 'for-upstream' of git://repo.or.cz/qemu/kevin:
vduse-blk: Add name option
vduse-blk: Add serial option
nbd: Drop dead code spotted by Coverity
aio_wait_kick: add missing memory barrier
block/gluster: correctly set max_pdiscard
block/rbd: report a better error when namespace does not exist
qsd: document vduse-blk exports
libvduse: Add support for reconnecting
vduse-blk: Add vduse-blk resize support
vduse-blk: Implement vduse-blk export
libvduse: Add VDUSE (vDPA Device in Userspace) library
linux-headers: Add vduse.h
block/export: Abstract out the logic of virtio-blk I/O process
block/export: Fix incorrect length passed to vu_queue_push()
block: Support passing NULL ops to blk_set_dev_ops()
block: simplify handling of try to merge different sized bitmaps
block: improve block_dirty_bitmap_merge(): don't allocate extra bitmap
block: block_dirty_bitmap_merge(): fix error path
block: get rid of blk->guest_block_size
block: drop unused bdrv_co_drain() API

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

show more ...

block/export: Abstract out the logic of virtio-blk I/O process

Abstract the common logic of virtio-blk I/O process to a function
named virtio_blk_process_req(). It's needed for the following commit.

block/export: Abstract out the logic of virtio-blk I/O process

Abstract the common logic of virtio-blk I/O process to a function
named virtio_blk_process_req(). It's needed for the following commit.

Signed-off-by: Xie Yongji <xieyongji@bytedance.com>
Message-Id: <20220523084611.91-4-xieyongji@bytedance.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

show more ...