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[PULL 21/22] block/file-posix: don't use functions calling AIO_WAIT_WHIL
From: |
Kevin Wolf |
Subject: |
[PULL 21/22] block/file-posix: don't use functions calling AIO_WAIT_WHILE in worker threads |
Date: |
Fri, 17 Feb 2023 16:09:53 +0100 |
From: Emanuele Giuseppe Esposito <eesposit@redhat.com>
When calling bdrv_getlength() in handle_aiocb_write_zeroes(), the
function creates a new coroutine and then waits that it finishes using
AIO_WAIT_WHILE.
The problem is that this function could also run in a worker thread,
that has a different AioContext from main loop and iothreads, therefore
in AIO_WAIT_WHILE we will have in_aio_context_home_thread(ctx) == false
and therefore
assert(qemu_get_current_aio_context() == qemu_get_aio_context());
in the else branch will fail, crashing QEMU.
Aside from that, bdrv_getlength() is wrong also conceptually, because
it reads the BDS graph from another thread and is not protected by
any lock.
Replace it with raw_co_getlength, that doesn't create a coroutine and
doesn't read the BDS graph.
Reported-by: Ninad Palsule <ninad@linux.vnet.ibm.com>
Suggested-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Message-Id: <20230209154522.1164401-1-eesposit@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
block/file-posix.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/block/file-posix.c b/block/file-posix.c
index d3073a7caa..9a99111f45 100644
--- a/block/file-posix.c
+++ b/block/file-posix.c
@@ -1738,7 +1738,7 @@ static int handle_aiocb_write_zeroes(void *opaque)
#ifdef CONFIG_FALLOCATE
/* Last resort: we are trying to extend the file with zeroed data. This
* can be done via fallocate(fd, 0) */
- len = bdrv_getlength(aiocb->bs);
+ len = raw_co_getlength(aiocb->bs);
if (s->has_fallocate && len >= 0 && aiocb->aio_offset >= len) {
int ret = do_fallocate(s->fd, 0, aiocb->aio_offset, aiocb->aio_nbytes);
if (ret == 0 || ret != -ENOTSUP) {
--
2.39.2
- [PULL 08/22] parallels: Fix .bdrv_co_create(_opts) to open images with no_co_wrapper, (continued)
- [PULL 08/22] parallels: Fix .bdrv_co_create(_opts) to open images with no_co_wrapper, Kevin Wolf, 2023/02/17
- [PULL 17/22] block: Assert non-coroutine context for bdrv_open_inherit(), Kevin Wolf, 2023/02/17
- [PULL 13/22] vhdx: Fix .bdrv_co_create(_opts) to open images with no_co_wrapper, Kevin Wolf, 2023/02/17
- [PULL 05/22] block-coroutine-wrapper: Introduce no_co_wrapper, Kevin Wolf, 2023/02/17
- [PULL 07/22] luks: Fix .bdrv_co_create(_opts) to open images with no_co_wrapper, Kevin Wolf, 2023/02/17
- [PULL 18/22] block: Handle curl 7.55.0, 7.85.0 version changes, Kevin Wolf, 2023/02/17
- [PULL 11/22] qed: Fix .bdrv_co_create(_opts) to open images with no_co_wrapper, Kevin Wolf, 2023/02/17
- [PULL 10/22] qcow2: Fix open/create to open images with no_co_wrapper, Kevin Wolf, 2023/02/17
- [PULL 19/22] block: temporarily hold the new AioContext of bs_top in bdrv_append(), Kevin Wolf, 2023/02/17
- [PULL 20/22] MAINTAINERS: drop Vladimir from parallels block driver, Kevin Wolf, 2023/02/17
- [PULL 21/22] block/file-posix: don't use functions calling AIO_WAIT_WHILE in worker threads,
Kevin Wolf <=
- [PULL 15/22] vpc: Fix .bdrv_co_create(_opts) to open images with no_co_wrapper, Kevin Wolf, 2023/02/17
- [PULL 16/22] block: Fix bdrv_co_create_opts_simple() to open images with no_co_wrapper, Kevin Wolf, 2023/02/17
- [PULL 14/22] vmdk: Fix .bdrv_co_create(_opts) to open images with no_co_wrapper, Kevin Wolf, 2023/02/17
- [PULL 22/22] hbitmap: fix hbitmap_status() return value for first dirty bit case, Kevin Wolf, 2023/02/17
- Re: [PULL 00/22] Block layer patches, Peter Maydell, 2023/02/20