qemu-patch-raspberry4/block
Roman Pen 5e1b34a3fa linux-aio: prevent submitting more than MAX_EVENTS
Invoking io_setup(MAX_EVENTS) we ask kernel to create ring buffer for us
with specified number of events.  But kernel ring buffer allocation logic
is a bit tricky (ring buffer is page size aligned + some percpu allocation
are required) so eventually more than requested events number is allocated.

From a userspace side we have to follow the convention and should not try
to io_submit() more or logic, which consumes completed events, should be
changed accordingly.  The pitfall is in the following sequence:

    MAX_EVENTS = 128
    io_setup(MAX_EVENTS)

    io_submit(MAX_EVENTS)
    io_submit(MAX_EVENTS)

    /* now 256 events are in-flight */

    io_getevents(MAX_EVENTS) = 128

    /* we can handle only 128 events at once, to be sure
     * that nothing is pended the io_getevents(MAX_EVENTS)
     * call must be invoked once more or hang will happen. */

To prevent the hang or reiteration of io_getevents() call this patch
restricts the number of in-flights, which is now limited to MAX_EVENTS.

Signed-off-by: Roman Pen <roman.penyaev@profitbricks.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-id: 1468415004-31755-1-git-send-email-roman.penyaev@profitbricks.com
Cc: Stefan Hajnoczi <stefanha@redhat.com>
Cc: qemu-devel@nongnu.org
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2016-07-18 15:10:52 +01:00
..
Makefile.objs block: Move bdrv_commit() to block/commit.c 2016-07-05 16:46:27 +02:00
accounting.c block: Clean up includes 2016-01-20 13:36:23 +01:00
archipelago.c coccinelle: Remove unnecessary variables for function return value 2016-06-20 16:38:13 +02:00
backup.c coroutine: move entry argument to qemu_coroutine_create 2016-07-13 13:26:02 +02:00
blkdebug.c coroutine: move entry argument to qemu_coroutine_create 2016-07-13 13:26:02 +02:00
blkreplay.c coroutine: move entry argument to qemu_coroutine_create 2016-07-13 13:26:02 +02:00
blkverify.c block: Convert bdrv_aio_writev() to BdrvChild 2016-07-05 16:46:26 +02:00
block-backend.c block/qdev: Allow configuring rerror/werror with qdev properties 2016-07-13 13:32:27 +02:00
bochs.c block: Convert bdrv_co_preadv/pwritev to BdrvChild 2016-07-05 16:46:27 +02:00
cloop.c block: Convert bdrv_pread(v) to BdrvChild 2016-07-05 16:46:27 +02:00
commit.c Improve block job rate limiting for small bandwidth values 2016-07-13 13:41:38 +02:00
crypto.c QAPI patches for 2016-07-06 2016-07-06 11:38:09 +01:00
curl.c block: always compile-check debug prints 2016-05-12 15:22:08 +02:00
dirty-bitmap.c include/qemu/osdep.h: Don't include qapi/error.h 2016-03-22 22:20:15 +01:00
dmg.c block: Convert bdrv_pread(v) to BdrvChild 2016-07-05 16:46:27 +02:00
gluster.c coroutine: move entry argument to qemu_coroutine_create 2016-07-13 13:26:02 +02:00
io.c coroutine: move entry argument to qemu_coroutine_create 2016-07-13 13:26:02 +02:00
iscsi.c coroutine: move entry argument to qemu_coroutine_create 2016-07-13 13:26:02 +02:00
linux-aio.c linux-aio: prevent submitting more than MAX_EVENTS 2016-07-18 15:10:52 +01:00
mirror.c Improve block job rate limiting for small bandwidth values 2016-07-13 13:41:38 +02:00
nbd-client.c coroutine: move entry argument to qemu_coroutine_create 2016-07-13 13:26:02 +02:00
nbd-client.h nbd: Simplify client FUA handling 2016-05-12 15:22:09 +02:00
nbd.c block: Switch discard length bounds to byte-based 2016-07-05 16:46:25 +02:00
nfs.c coroutine: move entry argument to qemu_coroutine_create 2016-07-13 13:26:02 +02:00
null.c block/null: Implement bdrv_refresh_filename() 2016-06-16 15:20:37 +02:00
parallels.c block: Convert bdrv_pwrite_zeroes() to BdrvChild 2016-07-05 16:46:27 +02:00
qapi.c qapi: Add new visit_complete() function 2016-07-06 10:52:04 +02:00
qcow.c coroutine: move entry argument to qemu_coroutine_create 2016-07-13 13:26:02 +02:00
qcow2-cache.c block: Convert bdrv_pwrite(v/_sync) to BdrvChild 2016-07-05 16:46:27 +02:00
qcow2-cluster.c qcow2: Fix qcow2_get_cluster_offset() 2016-07-13 13:41:38 +02:00
qcow2-refcount.c block/qcow2: Don't use cpu_to_*w() 2016-07-05 16:54:04 +02:00
qcow2-snapshot.c block: Convert bdrv_pwrite(v/_sync) to BdrvChild 2016-07-05 16:46:27 +02:00
qcow2.c coroutine: move entry argument to qemu_coroutine_create 2016-07-13 13:26:02 +02:00
qcow2.h qcow2: Implement .bdrv_co_pwritev() 2016-06-16 15:19:55 +02:00
qed-check.c qed: Use DIV_ROUND_UP 2016-06-07 18:19:24 +03:00
qed-cluster.c block: Clean up includes 2016-01-20 13:36:23 +01:00
qed-gencb.c block: Clean up includes 2016-01-20 13:36:23 +01:00
qed-l2-cache.c block: Clean up includes 2016-01-20 13:36:23 +01:00
qed-table.c block: Convert bdrv_aio_writev() to BdrvChild 2016-07-05 16:46:26 +02:00
qed.c coroutine: move entry argument to qemu_coroutine_create 2016-07-13 13:26:02 +02:00
qed.h util: move declarations out of qemu-common.h 2016-03-22 22:20:17 +01:00
quorum.c block: Convert bdrv_aio_writev() to BdrvChild 2016-07-05 16:46:26 +02:00
raw-posix.c linux-aio: share one LinuxAioState within an AioContext 2016-07-18 15:09:31 +01:00
raw-win32.c linux-aio: share one LinuxAioState within an AioContext 2016-07-18 15:09:31 +01:00
raw_bsd.c block: Convert bdrv_co_preadv/pwritev to BdrvChild 2016-07-05 16:46:27 +02:00
rbd.c coccinelle: Remove unnecessary variables for function return value 2016-06-20 16:38:13 +02:00
sheepdog.c coroutine: move entry argument to qemu_coroutine_create 2016-07-13 13:26:02 +02:00
snapshot.c error: Remove NULL checks on error_propagate() calls 2016-06-20 16:38:13 +02:00
ssh.c coroutine: move entry argument to qemu_coroutine_create 2016-07-13 13:26:02 +02:00
stream.c Improve block job rate limiting for small bandwidth values 2016-07-13 13:41:38 +02:00
throttle-groups.c block: Move I/O throttling configuration functions to BlockBackend 2016-05-19 16:45:30 +02:00
trace-events trace: split out trace events for block/ directory 2016-06-20 17:22:14 +01:00
vdi.c block: Convert bdrv_co_preadv/pwritev to BdrvChild 2016-07-05 16:46:27 +02:00
vhdx-endian.c qemu-common: stop including qemu/bswap.h from qemu-common.h 2016-05-19 16:42:28 +02:00
vhdx-log.c block: Convert bdrv_pwrite(v/_sync) to BdrvChild 2016-07-05 16:46:27 +02:00
vhdx.c block: Convert bdrv_pwrite(v/_sync) to BdrvChild 2016-07-05 16:46:27 +02:00
vhdx.h block: vhdx - update PAYLOAD_BLOCK_UNMAPPED value to match 1.00 spec 2014-12-12 15:42:22 +00:00
vmdk.c vmdk: fix metadata write regression 2016-07-13 13:41:39 +02:00
vpc.c block: Convert bdrv_co_preadv/pwritev to BdrvChild 2016-07-05 16:46:27 +02:00
vvfat.c vvfat: Fix qcow write target driver specification 2016-07-13 13:41:39 +02:00
win32-aio.c linux-aio: share one LinuxAioState within an AioContext 2016-07-18 15:09:31 +01:00
write-threshold.c block: Clean up includes 2016-01-20 13:36:23 +01:00