Commit 6cd5c9d7 authored by Kevin Wolf's avatar Kevin Wolf
Browse files

block: ignore_bds_parents parameter for drain functions 



In the future, bdrv_drained_all_begin/end() will drain all invidiual
nodes separately rather than whole subtrees. This means that we don't
want to propagate the drain to all parents any more: If the parent is a
BDS, it will already be drained separately. Recursing to all parents is
unnecessary work and would make it an O(n²) operation.

Prepare the drain function for the changed drain_all by adding an
ignore_bds_parents parameter to the internal implementation that
prevents the propagation of the drain to BDS parents. We still (have to)
propagate it to non-BDS parents like BlockBackends or Jobs because those
are not drained separately.

Signed-off-by: default avatarKevin Wolf <kwolf@redhat.com>
parent c8ca33d0

block.c

+7 −4
Original line number Diff line number Diff line
@@ -818,13 +818,13 @@ static char *bdrv_child_get_parent_desc(BdrvChild *c) 
static void bdrv_child_cb_drained_begin(BdrvChild *child)

{

    BlockDriverState *bs = child->opaque;

    bdrv_do_drained_begin_quiesce(bs, NULL);

    bdrv_do_drained_begin_quiesce(bs, NULL, false);

}



static bool bdrv_child_cb_drained_poll(BdrvChild *child)

{

    BlockDriverState *bs = child->opaque;

    return bdrv_drain_poll(bs, false, NULL);

    return bdrv_drain_poll(bs, false, NULL, false);

}



static void bdrv_child_cb_drained_end(BdrvChild *child)
@@ -908,6 +908,7 @@ static void bdrv_inherited_options(int *child_flags, QDict *child_options, 
}



const BdrvChildRole child_file = {

    .parent_is_bds   = true,

    .get_parent_desc = bdrv_child_get_parent_desc,

    .inherit_options = bdrv_inherited_options,

    .drained_begin   = bdrv_child_cb_drained_begin,
@@ -933,6 +934,7 @@ static void bdrv_inherited_fmt_options(int *child_flags, QDict *child_options, 
}



const BdrvChildRole child_format = {

    .parent_is_bds   = true,

    .get_parent_desc = bdrv_child_get_parent_desc,

    .inherit_options = bdrv_inherited_fmt_options,

    .drained_begin   = bdrv_child_cb_drained_begin,
@@ -1051,6 +1053,7 @@ static int bdrv_backing_update_filename(BdrvChild *c, BlockDriverState *base, 
}



const BdrvChildRole child_backing = {

    .parent_is_bds   = true,

    .get_parent_desc = bdrv_child_get_parent_desc,

    .attach          = bdrv_backing_attach,

    .detach          = bdrv_backing_detach,
@@ -4957,7 +4960,7 @@ void bdrv_set_aio_context(BlockDriverState *bs, AioContext *new_context) 
    AioContext *ctx = bdrv_get_aio_context(bs);



    aio_disable_external(ctx);

    bdrv_parent_drained_begin(bs, NULL);

    bdrv_parent_drained_begin(bs, NULL, false);

    bdrv_drain(bs); /* ensure there are no in-flight requests */



    while (aio_poll(ctx, false)) {
@@ -4971,7 +4974,7 @@ void bdrv_set_aio_context(BlockDriverState *bs, AioContext *new_context) 
     */

    aio_context_acquire(new_context);

    bdrv_attach_aio_context(bs, new_context);

    bdrv_parent_drained_end(bs, NULL);

    bdrv_parent_drained_end(bs, NULL, false);

    aio_enable_external(ctx);

    aio_context_release(new_context);

}

block/io.c

+53 −35
Original line number Diff line number Diff line
@@ -41,12 +41,13 @@ 
static int coroutine_fn bdrv_co_do_pwrite_zeroes(BlockDriverState *bs,

    int64_t offset, int bytes, BdrvRequestFlags flags);



void bdrv_parent_drained_begin(BlockDriverState *bs, BdrvChild *ignore)

void bdrv_parent_drained_begin(BlockDriverState *bs, BdrvChild *ignore,

                               bool ignore_bds_parents)

{

    BdrvChild *c, *next;



    QLIST_FOREACH_SAFE(c, &bs->parents, next_parent, next) {

        if (c == ignore) {

        if (c == ignore || (ignore_bds_parents && c->role->parent_is_bds)) {

            continue;

        }

        if (c->role->drained_begin) {
@@ -55,12 +56,13 @@ void bdrv_parent_drained_begin(BlockDriverState *bs, BdrvChild *ignore) 
    }

}



void bdrv_parent_drained_end(BlockDriverState *bs, BdrvChild *ignore)

void bdrv_parent_drained_end(BlockDriverState *bs, BdrvChild *ignore,

                             bool ignore_bds_parents)

{

    BdrvChild *c, *next;



    QLIST_FOREACH_SAFE(c, &bs->parents, next_parent, next) {

        if (c == ignore) {

        if (c == ignore || (ignore_bds_parents && c->role->parent_is_bds)) {

            continue;

        }

        if (c->role->drained_end) {
@@ -69,13 +71,14 @@ void bdrv_parent_drained_end(BlockDriverState *bs, BdrvChild *ignore) 
    }

}



static bool bdrv_parent_drained_poll(BlockDriverState *bs, BdrvChild *ignore)

static bool bdrv_parent_drained_poll(BlockDriverState *bs, BdrvChild *ignore,

                                     bool ignore_bds_parents)

{

    BdrvChild *c, *next;

    bool busy = false;



    QLIST_FOREACH_SAFE(c, &bs->parents, next_parent, next) {

        if (c == ignore) {

        if (c == ignore || (ignore_bds_parents && c->role->parent_is_bds)) {

            continue;

        }

        if (c->role->drained_poll) {
@@ -167,6 +170,7 @@ typedef struct { 
    bool recursive;

    bool poll;

    BdrvChild *parent;

    bool ignore_bds_parents;

} BdrvCoDrainData;



static void coroutine_fn bdrv_drain_invoke_entry(void *opaque)
@@ -220,11 +224,11 @@ static void bdrv_drain_invoke(BlockDriverState *bs, bool begin) 


/* Returns true if BDRV_POLL_WHILE() should go into a blocking aio_poll() */

bool bdrv_drain_poll(BlockDriverState *bs, bool recursive,

                     BdrvChild *ignore_parent)

                     BdrvChild *ignore_parent, bool ignore_bds_parents)

{

    BdrvChild *child, *next;



    if (bdrv_parent_drained_poll(bs, ignore_parent)) {

    if (bdrv_parent_drained_poll(bs, ignore_parent, ignore_bds_parents)) {

        return true;

    }
@@ -233,8 +237,9 @@ bool bdrv_drain_poll(BlockDriverState *bs, bool recursive, 
    }



    if (recursive) {

        assert(!ignore_bds_parents);

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

            if (bdrv_drain_poll(child->bs, recursive, child)) {

            if (bdrv_drain_poll(child->bs, recursive, child, false)) {

                return true;

            }

        }
@@ -250,13 +255,14 @@ static bool bdrv_drain_poll_top_level(BlockDriverState *bs, bool recursive, 
     * have executed. */

    while (aio_poll(bs->aio_context, false));



    return bdrv_drain_poll(bs, recursive, ignore_parent);

    return bdrv_drain_poll(bs, recursive, ignore_parent, false);

}



static void bdrv_do_drained_begin(BlockDriverState *bs, bool recursive,

                                  BdrvChild *parent, bool poll);

                                  BdrvChild *parent, bool ignore_bds_parents,

                                  bool poll);

static void bdrv_do_drained_end(BlockDriverState *bs, bool recursive,

                                BdrvChild *parent);

                                BdrvChild *parent, bool ignore_bds_parents);



static void bdrv_co_drain_bh_cb(void *opaque)

{
@@ -267,9 +273,11 @@ static void bdrv_co_drain_bh_cb(void *opaque) 
    if (bs) {

        bdrv_dec_in_flight(bs);

        if (data->begin) {

            bdrv_do_drained_begin(bs, data->recursive, data->parent, data->poll);

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

                                  data->ignore_bds_parents, data->poll);

        } else {

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

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

                                data->ignore_bds_parents);

        }

    } else {

        assert(data->begin);
@@ -282,7 +290,9 @@ static void bdrv_co_drain_bh_cb(void *opaque) 


static void coroutine_fn bdrv_co_yield_to_drain(BlockDriverState *bs,

                                                bool begin, bool recursive,

                                                BdrvChild *parent, bool poll)

                                                BdrvChild *parent,

                                                bool ignore_bds_parents,

                                                bool poll)

{

    BdrvCoDrainData data;
@@ -297,6 +307,7 @@ static void coroutine_fn bdrv_co_yield_to_drain(BlockDriverState *bs, 
        .begin = begin,

        .recursive = recursive,

        .parent = parent,

        .ignore_bds_parents = ignore_bds_parents,

        .poll = poll,

    };

    if (bs) {
@@ -312,7 +323,7 @@ static void coroutine_fn bdrv_co_yield_to_drain(BlockDriverState *bs, 
}



void bdrv_do_drained_begin_quiesce(BlockDriverState *bs,

                                   BdrvChild *parent)

                                   BdrvChild *parent, bool ignore_bds_parents)

{

    assert(!qemu_in_coroutine());
@@ -321,26 +332,30 @@ void bdrv_do_drained_begin_quiesce(BlockDriverState *bs, 
        aio_disable_external(bdrv_get_aio_context(bs));

    }



    bdrv_parent_drained_begin(bs, parent);

    bdrv_parent_drained_begin(bs, parent, ignore_bds_parents);

    bdrv_drain_invoke(bs, true);

}



static void bdrv_do_drained_begin(BlockDriverState *bs, bool recursive,

                                  BdrvChild *parent, bool poll)

                                  BdrvChild *parent, bool ignore_bds_parents,

                                  bool poll)

{

    BdrvChild *child, *next;



    if (qemu_in_coroutine()) {

        bdrv_co_yield_to_drain(bs, true, recursive, parent, poll);

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

                               poll);

        return;

    }



    bdrv_do_drained_begin_quiesce(bs, parent);

    bdrv_do_drained_begin_quiesce(bs, parent, ignore_bds_parents);



    if (recursive) {

        assert(!ignore_bds_parents);

        bs->recursive_quiesce_counter++;

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

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

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

                                  false);

        }

    }
@@ -354,28 +369,30 @@ static void bdrv_do_drained_begin(BlockDriverState *bs, bool recursive, 
     * nodes.

     */

    if (poll) {

        assert(!ignore_bds_parents);

        BDRV_POLL_WHILE(bs, bdrv_drain_poll_top_level(bs, recursive, parent));

    }

}



void bdrv_drained_begin(BlockDriverState *bs)

{

    bdrv_do_drained_begin(bs, false, NULL, true);

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

}



void bdrv_subtree_drained_begin(BlockDriverState *bs)

{

    bdrv_do_drained_begin(bs, true, NULL, true);

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

}



void bdrv_do_drained_end(BlockDriverState *bs, bool recursive,

                         BdrvChild *parent)

static void bdrv_do_drained_end(BlockDriverState *bs, bool recursive,

                                BdrvChild *parent, bool ignore_bds_parents)

{

    BdrvChild *child, *next;

    int old_quiesce_counter;



    if (qemu_in_coroutine()) {

        bdrv_co_yield_to_drain(bs, false, recursive, parent, false);

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

                               false);

        return;

    }

    assert(bs->quiesce_counter > 0);
@@ -383,27 +400,28 @@ void bdrv_do_drained_end(BlockDriverState *bs, bool recursive, 


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

    bdrv_drain_invoke(bs, false);

    bdrv_parent_drained_end(bs, parent);

    bdrv_parent_drained_end(bs, parent, ignore_bds_parents);

    if (old_quiesce_counter == 1) {

        aio_enable_external(bdrv_get_aio_context(bs));

    }



    if (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);

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

        }

    }

}



void bdrv_drained_end(BlockDriverState *bs)

{

    bdrv_do_drained_end(bs, false, NULL);

    bdrv_do_drained_end(bs, false, NULL, false);

}



void bdrv_subtree_drained_end(BlockDriverState *bs)

{

    bdrv_do_drained_end(bs, true, NULL);

    bdrv_do_drained_end(bs, true, NULL, false);

}



void bdrv_apply_subtree_drain(BdrvChild *child, BlockDriverState *new_parent)
@@ -411,7 +429,7 @@ void bdrv_apply_subtree_drain(BdrvChild *child, BlockDriverState *new_parent) 
    int i;



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

        bdrv_do_drained_begin(child->bs, true, child, true);

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

    }

}
@@ -420,7 +438,7 @@ 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);

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

    }

}
@@ -472,7 +490,7 @@ void bdrv_drain_all_begin(void) 
    BdrvNextIterator it;



    if (qemu_in_coroutine()) {

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

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

        return;

    }
@@ -486,7 +504,7 @@ void bdrv_drain_all_begin(void) 
        AioContext *aio_context = bdrv_get_aio_context(bs);



        aio_context_acquire(aio_context);

        bdrv_do_drained_begin(bs, true, NULL, true);

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

        aio_context_release(aio_context);

    }
@@ -504,7 +522,7 @@ void bdrv_drain_all_end(void) 
        AioContext *aio_context = bdrv_get_aio_context(bs);



        aio_context_acquire(aio_context);

        bdrv_do_drained_end(bs, true, NULL);

        bdrv_do_drained_end(bs, true, NULL, false);

        aio_context_release(aio_context);

    }

}

block/vvfat.c

+1 −0
Original line number Diff line number Diff line
@@ -3134,6 +3134,7 @@ static void vvfat_qcow_options(int *child_flags, QDict *child_options, 
}



static const BdrvChildRole child_vvfat_qcow = {

    .parent_is_bds      = true,

    .inherit_options    = vvfat_qcow_options,

};

include/block/block.h

+11 −5
Original line number Diff line number Diff line
@@ -557,7 +557,8 @@ void bdrv_io_unplug(BlockDriverState *bs); 
 * Begin a quiesced section of all users of @bs. This is part of

 * bdrv_drained_begin.

 */

void bdrv_parent_drained_begin(BlockDriverState *bs, BdrvChild *ignore);

void bdrv_parent_drained_begin(BlockDriverState *bs, BdrvChild *ignore,

                               bool ignore_bds_parents);



/**

 * bdrv_parent_drained_end:
@@ -565,18 +566,23 @@ void bdrv_parent_drained_begin(BlockDriverState *bs, BdrvChild *ignore); 
 * End a quiesced section of all users of @bs. This is part of

 * bdrv_drained_end.

 */

void bdrv_parent_drained_end(BlockDriverState *bs, BdrvChild *ignore);

void bdrv_parent_drained_end(BlockDriverState *bs, BdrvChild *ignore,

                             bool ignore_bds_parents);



/**

 * bdrv_drain_poll:

 *

 * Poll for pending requests in @bs, its parents (except for @ignore_parent),

 * and if @recursive is true its children as well.

 * and if @recursive is true its children as well (used for subtree drain).

 *

 * If @ignore_bds_parents is true, parents that are BlockDriverStates must

 * ignore the drain request because they will be drained separately (used for

 * drain_all).

 *

 * This is part of bdrv_drained_begin.

 */

bool bdrv_drain_poll(BlockDriverState *bs, bool recursive,

                     BdrvChild *ignore_parent);

                     BdrvChild *ignore_parent, bool ignore_bds_parents);



/**

 * bdrv_drained_begin:
@@ -597,7 +603,7 @@ void bdrv_drained_begin(BlockDriverState *bs); 
 * running requests to complete.

 */

void bdrv_do_drained_begin_quiesce(BlockDriverState *bs,

                                   BdrvChild *parent);

                                   BdrvChild *parent, bool ignore_bds_parents);



/**

 * Like bdrv_drained_begin, but recursively begins a quiesced section for

include/block/block_int.h

+6 −0
Original line number Diff line number Diff line
@@ -577,6 +577,12 @@ struct BdrvChildRole { 
     * points to. */

    bool stay_at_node;



    /* If true, the parent is a BlockDriverState and bdrv_next_all_states()

     * will return it. This information is used for drain_all, where every node

     * will be drained separately, so the drain only needs to be propagated to

     * non-BDS parents. */

    bool parent_is_bds;



    void (*inherit_options)(int *child_flags, QDict *child_options,

                            int parent_flags, QDict *parent_options);