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rbd: Fix race between aio completition and aio cancel

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This one fixes a race which qemu had also in iscsi block driver
between cancellation and io completition.

qemu_rbd_aio_cancel was not synchronously waiting for the end of
the command.

To archieve this it introduces a new status flag which uses
-EINPROGRESS.

Signed-off-by: Stefan Priebe <s.priebe@profihost.ag>
Reviewed-by: Stefan Hajnoczi <stefanha@gmail.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Stefan Priebe 2012-11-30 09:55:46 +01:00 committed by Kevin Wolf
parent 791bfa35ee
commit 473c7f0255
1 changed files with 12 additions and 8 deletions
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20
block/rbd.c
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@ -77,6 +77,7 @@ typedef struct RBDAIOCB {
int error;
struct BDRVRBDState *s;
int cancelled;
int status;
} RBDAIOCB;
typedef struct RADOSCB {
@ -376,12 +377,6 @@ static void qemu_rbd_complete_aio(RADOSCB *rcb)
RBDAIOCB *acb = rcb->acb;
int64_t r;
if (acb->cancelled) {
qemu_vfree(acb->bounce);
qemu_aio_release(acb);
goto done;
}
r = rcb->ret;
if (acb->cmd == RBD_AIO_WRITE ||
@ -409,7 +404,6 @@ static void qemu_rbd_complete_aio(RADOSCB *rcb)
/* Note that acb->bh can be NULL in case where the aio was cancelled */
acb->bh = qemu_bh_new(rbd_aio_bh_cb, acb);
qemu_bh_schedule(acb->bh);
done:
g_free(rcb);
}
@ -568,6 +562,12 @@ static void qemu_rbd_aio_cancel(BlockDriverAIOCB *blockacb)
{
RBDAIOCB *acb = (RBDAIOCB *) blockacb;
acb->cancelled = 1;
while (acb->status == -EINPROGRESS) {
qemu_aio_wait();
}
qemu_aio_release(acb);
}
static const AIOCBInfo rbd_aiocb_info = {
@ -639,8 +639,11 @@ static void rbd_aio_bh_cb(void *opaque)
acb->common.cb(acb->common.opaque, (acb->ret > 0 ? 0 : acb->ret));
qemu_bh_delete(acb->bh);
acb->bh = NULL;
acb->status = 0;
qemu_aio_release(acb);
if (!acb->cancelled) {
qemu_aio_release(acb);
}
}
static int rbd_aio_discard_wrapper(rbd_image_t image,
@ -685,6 +688,7 @@ static BlockDriverAIOCB *rbd_start_aio(BlockDriverState *bs,
acb->s = s;
acb->cancelled = 0;
acb->bh = NULL;
acb->status = -EINPROGRESS;
if (cmd == RBD_AIO_WRITE) {
qemu_iovec_to_buf(acb->qiov, 0, acb->bounce, qiov->size);