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authorStefan Hajnoczi <stefanha@redhat.com>2016-03-08 10:11:16 +0000
committerStefan Hajnoczi <stefanha@redhat.com>2016-03-17 09:50:14 +0000
commit1f3ddfcb258e6e0562467a9644daad3f28597da8 (patch)
treef6cfc2b655d997660b63add838cc64f24124cc65
parent147dfab747dd1720cb6350b6b746ca84e15f9a24 (diff)
Revert "qed: Implement .bdrv_drain"
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 <pbonzini@redhat.com> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com> Acked-by: Paolo Bonzini <pbonzini@redhat.com> Message-id: 1457431876-8475-1-git-send-email-stefanha@redhat.com
-rw-r--r--block/qed.c13
1 files changed, 0 insertions, 13 deletions
diff --git a/block/qed.c b/block/qed.c
index 8de7dd0832..5a58856ecd 100644
--- a/block/qed.c
+++ b/block/qed.c
@@ -377,18 +377,6 @@ 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)
{
@@ -1694,7 +1682,6 @@ 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)