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[Qemu-devel] [PATCH] Revert "qed: Implement .bdrv_drain"
From: |
Stefan Hajnoczi |
Subject: |
[Qemu-devel] [PATCH] Revert "qed: Implement .bdrv_drain" |
Date: |
Tue, 8 Mar 2016 10:11:16 +0000 |
This reverts commit df9a681dc9ad41c9cdeb9ecc5d060ba9abd27e01.
Note that commit df9a681dc9ad41c9cdeb9ecc5d060ba9abd27e01 included some
unrelated hunks, possibly due to a merge failure or an overlooked
squash. This only reverts the qed .bdrv_drain() implementation.
The qed .bdrv_drain() implementation is unsafe and can lead to a double
request completion.
Paolo Bonzini reports:
"The problem is that bdrv_qed_drain calls qed_plug_allocating_write_reqs
unconditionally, but this is not correct if an allocating write is
queued. In this case, qed_unplug_allocating_write_reqs will restart the
allocating write and possibly cause it to complete. The aiocb however
is still in use for the L2/L1 table writes, and will then be completed
again as soon as the table writes are stable."
For QEMU 2.6 we can simply revert this commit. A full solution for the
qed need check timer may be added if the bdrv_drain() implementation is
extended.
Reported-by: Paolo Bonzini <address@hidden>
Signed-off-by: Stefan Hajnoczi <address@hidden>
---
block/qed.c | 13 -------------
1 file changed, 13 deletions(-)
Passes ./check -qed.
diff --git a/block/qed.c b/block/qed.c
index 404be1e..3da8021 100644
--- a/block/qed.c
+++ b/block/qed.c
@@ -376,18 +376,6 @@ static void bdrv_qed_attach_aio_context(BlockDriverState
*bs,
}
}
-static void bdrv_qed_drain(BlockDriverState *bs)
-{
- BDRVQEDState *s = bs->opaque;
-
- /* Cancel timer and start doing I/O that were meant to happen as if it
- * fired, that way we get bdrv_drain() taking care of the ongoing requests
- * correctly. */
- qed_cancel_need_check_timer(s);
- qed_plug_allocating_write_reqs(s);
- bdrv_aio_flush(s->bs, qed_clear_need_check, s);
-}
-
static int bdrv_qed_open(BlockDriverState *bs, QDict *options, int flags,
Error **errp)
{
@@ -1692,7 +1680,6 @@ static BlockDriver bdrv_qed = {
.bdrv_check = bdrv_qed_check,
.bdrv_detach_aio_context = bdrv_qed_detach_aio_context,
.bdrv_attach_aio_context = bdrv_qed_attach_aio_context,
- .bdrv_drain = bdrv_qed_drain,
};
static void bdrv_qed_init(void)
--
2.5.0
- [Qemu-devel] [PATCH] Revert "qed: Implement .bdrv_drain",
Stefan Hajnoczi <=