| Message ID | 1458137817-15383-6-git-send-email-pbonzini@redhat.com |
|---|---|
| State | New |
| Headers | show |
On Wed, 03/16 15:16, Paolo Bonzini wrote: > Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> > --- > v1->v2: use aio_bh_new() [Fam] > > block/mirror.c | 24 ++++++++++++++++++++---- > 1 file changed, 20 insertions(+), 4 deletions(-) > > diff --git a/block/mirror.c b/block/mirror.c > index 9635fa8..2c7874d 100644 > --- a/block/mirror.c > +++ b/block/mirror.c > @@ -72,6 +72,7 @@ typedef struct MirrorOp { > QEMUIOVector qiov; > int64_t sector_num; > int nb_sectors; > + QEMUBH *co_enter_bh; > } MirrorOp; > > static BlockErrorAction mirror_error_action(MirrorBlockJob *s, bool read, > @@ -87,6 +88,18 @@ static BlockErrorAction mirror_error_action(MirrorBlockJob *s, bool read, > } > } > > +static void mirror_bh_cb(void *opaque) > +{ > + MirrorOp *op = opaque; > + MirrorBlockJob *s = op->s; > + > + qemu_bh_delete(op->co_enter_bh); > + g_free(op); > + if (s->waiting_for_io) { > + qemu_coroutine_enter(s->common.co, NULL); > + } > +} > + > static void mirror_iteration_done(MirrorOp *op, int ret) > { > MirrorBlockJob *s = op->s; > @@ -117,11 +130,14 @@ static void mirror_iteration_done(MirrorOp *op, int ret) > } > > qemu_iovec_destroy(&op->qiov); > - g_free(op); > > - if (s->waiting_for_io) { > - qemu_coroutine_enter(s->common.co, NULL); > - } > + /* The I/O operation is not finished until the callback returns. > + * If we call qemu_coroutine_enter here, there is the possibility > + * of a deadlock when the coroutine calls bdrv_drained_begin. > + */ > + op->co_enter_bh = aio_bh_new(bdrv_get_aio_context(s->target), > + mirror_bh_cb, op); > + qemu_bh_schedule(op->co_enter_bh); I think we can conditionally create the BH only if s->waiting_for_io is true, but the else branch is less important, so: Reviewed-by: Fam Zheng <famz@redhat.com>
diff --git a/block/mirror.c b/block/mirror.c index 9635fa8..2c7874d 100644 --- a/block/mirror.c +++ b/block/mirror.c @@ -72,6 +72,7 @@ typedef struct MirrorOp { QEMUIOVector qiov; int64_t sector_num; int nb_sectors; + QEMUBH *co_enter_bh; } MirrorOp; static BlockErrorAction mirror_error_action(MirrorBlockJob *s, bool read, @@ -87,6 +88,18 @@ static BlockErrorAction mirror_error_action(MirrorBlockJob *s, bool read, } } +static void mirror_bh_cb(void *opaque) +{ + MirrorOp *op = opaque; + MirrorBlockJob *s = op->s; + + qemu_bh_delete(op->co_enter_bh); + g_free(op); + if (s->waiting_for_io) { + qemu_coroutine_enter(s->common.co, NULL); + } +} + static void mirror_iteration_done(MirrorOp *op, int ret) { MirrorBlockJob *s = op->s; @@ -117,11 +130,14 @@ static void mirror_iteration_done(MirrorOp *op, int ret) } qemu_iovec_destroy(&op->qiov); - g_free(op); - if (s->waiting_for_io) { - qemu_coroutine_enter(s->common.co, NULL); - } + /* The I/O operation is not finished until the callback returns. + * If we call qemu_coroutine_enter here, there is the possibility + * of a deadlock when the coroutine calls bdrv_drained_begin. + */ + op->co_enter_bh = aio_bh_new(bdrv_get_aio_context(s->target), + mirror_bh_cb, op); + qemu_bh_schedule(op->co_enter_bh); } static void mirror_write_complete(void *opaque, int ret)
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> --- v1->v2: use aio_bh_new() [Fam] block/mirror.c | 24 ++++++++++++++++++++---- 1 file changed, 20 insertions(+), 4 deletions(-)