From b4a41557a3fd97307e750c84916f9d2237f08242 Mon Sep 17 00:00:00 2001

From: Kevin Wolf <kwolf@redhat.com>

Date: Wed, 10 Oct 2018 20:21:47 +0100

Subject: [PATCH 21/49] block: ignore_bds_parents parameter for drain functions

MIME-Version: 1.0

Content-Type: text/plain; charset=UTF-8

Content-Transfer-Encoding: 8bit

RH-Author: Kevin Wolf <kwolf@redhat.com>

Message-id: <20181010202213.7372-9-kwolf@redhat.com>

Patchwork-id: 82598

O-Subject: [RHEL-8 qemu-kvm PATCH 18/44] block: ignore_bds_parents parameter for drain functions

Bugzilla: 1637976

RH-Acked-by: Max Reitz <mreitz@redhat.com>

RH-Acked-by: John Snow <jsnow@redhat.com>

RH-Acked-by: Thomas Huth <thuth@redhat.com>

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: Kevin Wolf <kwolf@redhat.com>

(cherry picked from commit 6cd5c9d7b2df93ef54144f170d4c908934a4767f)

Signed-off-by: Kevin Wolf <kwolf@redhat.com>

Signed-off-by: Danilo C. L. de Paula <ddepaula@redhat.com>

---

 block.c                   | 11 +++---

 block/io.c                | 88 ++++++++++++++++++++++++++++-------------------

 block/vvfat.c             |  1 +

 include/block/block.h     | 16 ++++++---

 include/block/block_int.h |  6 ++++

 5 files changed, 78 insertions(+), 44 deletions(-)

diff --git a/block.c b/block.c

index 5a50de6..519be6e 100644

--- a/block.c

+++ b/block.c

@@ -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,

@@ -4901,7 +4904,7 @@ 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)) {

@@ -4915,7 +4918,7 @@ 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);

 }

diff --git a/block/io.c b/block/io.c

index b58c91b..0021fefd 100644

--- a/block/io.c

+++ b/block/io.c

@@ -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) {

@@ -166,6 +169,7 @@ typedef struct {

     bool recursive;

     bool poll;

     BdrvChild *parent;

+    bool ignore_bds_parents;

 } BdrvCoDrainData;

 static void coroutine_fn bdrv_drain_invoke_entry(void *opaque)

@@ -219,11 +223,11 @@ 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;

     }

@@ -232,8 +236,9 @@ 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;

             }

         }

@@ -249,13 +254,14 @@ 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)

 {

@@ -266,9 +272,11 @@ 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);

@@ -281,7 +289,9 @@ 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;

@@ -296,6 +306,7 @@ 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) {

@@ -311,7 +322,7 @@ 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());

@@ -320,26 +331,30 @@ 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);

         }

     }

@@ -353,28 +368,30 @@ 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);

@@ -382,27 +399,28 @@ 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)

@@ -410,7 +428,7 @@ 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);

     }

 }

@@ -419,7 +437,7 @@ 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);

     }

 }

@@ -471,7 +489,7 @@ 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;

     }

@@ -485,7 +503,7 @@ 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);

     }

@@ -503,7 +521,7 @@ 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);

     }

 }

diff --git a/block/vvfat.c b/block/vvfat.c

index 4595f33..c7d2ed2 100644

--- a/block/vvfat.c

+++ b/block/vvfat.c

@@ -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,

 };

diff --git a/include/block/block.h b/include/block/block.h

index 43f29b5..6e91803 100644

--- a/include/block/block.h

+++ b/include/block/block.h

@@ -585,7 +585,8 @@ 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:

@@ -593,18 +594,23 @@ 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:

@@ -625,7 +631,7 @@ 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

diff --git a/include/block/block_int.h b/include/block/block_int.h

index beeacde..0ad8a76 100644

--- a/include/block/block_int.h

+++ b/include/block/block_int.h

@@ -582,6 +582,12 @@ 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);

-- 

1.8.3.1