Commit 8e1da77e authored by Max Reitz's avatar Max Reitz Committed by Kevin Wolf
Browse files

block: Add @drained_end_counter 



Callers can now pass a pointer to an integer that bdrv_drain_invoke()
(and its recursive callees) will increment for every
bdrv_drain_invoke_entry() operation they schedule.
bdrv_drain_invoke_entry() in turn will decrement it once it has invoked
BlockDriver.bdrv_co_drain_end().

We use atomic operations to access the pointee, because the
bdrv_do_drained_end() caller may wish to end drained sections for
multiple nodes in different AioContexts (bdrv_drain_all_end() does, for
example).

This is the first step to moving the polling for BdrvCoDrainData.done to
become true out of bdrv_drain_invoke() and into the root drained_end
function.

Signed-off-by: default avatarMax Reitz <mreitz@redhat.com>
Signed-off-by: default avatarKevin Wolf <kwolf@redhat.com>
parent 8e442810

block/io.c

+40 −18
Original line number Diff line number Diff line
@@ -194,6 +194,7 @@ typedef struct { 
    bool poll;

    BdrvChild *parent;

    bool ignore_bds_parents;

    int *drained_end_counter;

} BdrvCoDrainData;



static void coroutine_fn bdrv_drain_invoke_entry(void *opaque)
@@ -211,13 +212,18 @@ static void coroutine_fn bdrv_drain_invoke_entry(void *opaque) 
    atomic_mb_set(&data->done, true);

    bdrv_dec_in_flight(bs);



    if (data->begin) {

    if (data->drained_end_counter) {

        atomic_dec(data->drained_end_counter);

    }



    if (data->begin || data->drained_end_counter) {

        g_free(data);

    }

}



/* Recursively call BlockDriver.bdrv_co_drain_begin/end callbacks */

static void bdrv_drain_invoke(BlockDriverState *bs, bool begin)

static void bdrv_drain_invoke(BlockDriverState *bs, bool begin,

                              int *drained_end_counter)

{

    BdrvCoDrainData *data;
@@ -230,16 +236,25 @@ static void bdrv_drain_invoke(BlockDriverState *bs, bool begin) 
    *data = (BdrvCoDrainData) {

        .bs = bs,

        .done = false,

        .begin = begin

        .begin = begin,

        .drained_end_counter = drained_end_counter,

    };



    if (!begin && drained_end_counter) {

        atomic_inc(drained_end_counter);

    }



    /* Make sure the driver callback completes during the polling phase for

     * drain_begin. */

    bdrv_inc_in_flight(bs);

    data->co = qemu_coroutine_create(bdrv_drain_invoke_entry, data);

    aio_co_schedule(bdrv_get_aio_context(bs), data->co);



    if (!begin) {

    /*

     * TODO: Drop this and make callers pass @drained_end_counter and poll

     * themselves

     */

    if (!begin && !drained_end_counter) {

        BDRV_POLL_WHILE(bs, !data->done);

        g_free(data);

    }
@@ -281,7 +296,8 @@ static void bdrv_do_drained_begin(BlockDriverState *bs, bool recursive, 
                                  BdrvChild *parent, bool ignore_bds_parents,

                                  bool poll);

static void bdrv_do_drained_end(BlockDriverState *bs, bool recursive,

                                BdrvChild *parent, bool ignore_bds_parents);

                                BdrvChild *parent, bool ignore_bds_parents,

                                int *drained_end_counter);



static void bdrv_co_drain_bh_cb(void *opaque)

{
@@ -308,7 +324,8 @@ static void bdrv_co_drain_bh_cb(void *opaque) 
                                  data->ignore_bds_parents, data->poll);

        } else {

            bdrv_do_drained_end(bs, data->recursive, data->parent,

                                data->ignore_bds_parents);

                                data->ignore_bds_parents,

                                data->drained_end_counter);

        }

        if (ctx == co_ctx) {

            aio_context_release(ctx);
@@ -326,7 +343,8 @@ static void coroutine_fn bdrv_co_yield_to_drain(BlockDriverState *bs, 
                                                bool begin, bool recursive,

                                                BdrvChild *parent,

                                                bool ignore_bds_parents,

                                                bool poll)

                                                bool poll,

                                                int *drained_end_counter)

{

    BdrvCoDrainData data;
@@ -343,7 +361,9 @@ static void coroutine_fn bdrv_co_yield_to_drain(BlockDriverState *bs, 
        .parent = parent,

        .ignore_bds_parents = ignore_bds_parents,

        .poll = poll,

        .drained_end_counter = drained_end_counter,

    };



    if (bs) {

        bdrv_inc_in_flight(bs);

    }
@@ -367,7 +387,7 @@ void bdrv_do_drained_begin_quiesce(BlockDriverState *bs, 
    }



    bdrv_parent_drained_begin(bs, parent, ignore_bds_parents);

    bdrv_drain_invoke(bs, true);

    bdrv_drain_invoke(bs, true, NULL);

}



static void bdrv_do_drained_begin(BlockDriverState *bs, bool recursive,
@@ -378,7 +398,7 @@ static void bdrv_do_drained_begin(BlockDriverState *bs, bool recursive, 


    if (qemu_in_coroutine()) {

        bdrv_co_yield_to_drain(bs, true, recursive, parent, ignore_bds_parents,

                               poll);

                               poll, NULL);

        return;

    }
@@ -419,20 +439,21 @@ void bdrv_subtree_drained_begin(BlockDriverState *bs) 
}



static void bdrv_do_drained_end(BlockDriverState *bs, bool recursive,

                                BdrvChild *parent, bool ignore_bds_parents)

                                BdrvChild *parent, bool ignore_bds_parents,

                                int *drained_end_counter)

{

    BdrvChild *child, *next;

    int old_quiesce_counter;



    if (qemu_in_coroutine()) {

        bdrv_co_yield_to_drain(bs, false, recursive, parent, ignore_bds_parents,

                               false);

                               false, drained_end_counter);

        return;

    }

    assert(bs->quiesce_counter > 0);



    /* Re-enable things in child-to-parent order */

    bdrv_drain_invoke(bs, false);

    bdrv_drain_invoke(bs, false, drained_end_counter);

    bdrv_parent_drained_end(bs, parent, ignore_bds_parents);



    old_quiesce_counter = atomic_fetch_dec(&bs->quiesce_counter);
@@ -444,19 +465,20 @@ static void bdrv_do_drained_end(BlockDriverState *bs, bool recursive, 
        assert(!ignore_bds_parents);

        bs->recursive_quiesce_counter--;

        QLIST_FOREACH_SAFE(child, &bs->children, next, next) {

            bdrv_do_drained_end(child->bs, true, child, ignore_bds_parents);

            bdrv_do_drained_end(child->bs, true, child, ignore_bds_parents,

                                drained_end_counter);

        }

    }

}



void bdrv_drained_end(BlockDriverState *bs)

{

    bdrv_do_drained_end(bs, false, NULL, false);

    bdrv_do_drained_end(bs, false, NULL, false, NULL);

}



void bdrv_subtree_drained_end(BlockDriverState *bs)

{

    bdrv_do_drained_end(bs, true, NULL, false);

    bdrv_do_drained_end(bs, true, NULL, false, NULL);

}



void bdrv_apply_subtree_drain(BdrvChild *child, BlockDriverState *new_parent)
@@ -473,7 +495,7 @@ void bdrv_unapply_subtree_drain(BdrvChild *child, BlockDriverState *old_parent) 
    int i;



    for (i = 0; i < old_parent->recursive_quiesce_counter; i++) {

        bdrv_do_drained_end(child->bs, true, child, false);

        bdrv_do_drained_end(child->bs, true, child, false, NULL);

    }

}
@@ -543,7 +565,7 @@ void bdrv_drain_all_begin(void) 
    BlockDriverState *bs = NULL;



    if (qemu_in_coroutine()) {

        bdrv_co_yield_to_drain(NULL, true, false, NULL, true, true);

        bdrv_co_yield_to_drain(NULL, true, false, NULL, true, true, NULL);

        return;

    }
@@ -579,7 +601,7 @@ void bdrv_drain_all_end(void) 
        AioContext *aio_context = bdrv_get_aio_context(bs);



        aio_context_acquire(aio_context);

        bdrv_do_drained_end(bs, false, NULL, true);

        bdrv_do_drained_end(bs, false, NULL, true, NULL);

        aio_context_release(aio_context);

    }