Upcoming patches want to add some basic bitmap manipulation abilities
to qemu-img.  But blockdev.o is too heavyweight to link into qemu-img
(among other things, it would drag in block jobs and transaction
support - qemu-img does offline manipulation, where atomicity is less
important because there are no concurrent modifications to compete
with), so it's time to split off the bare bones of what we will need
into a new file blockbitmaps.o.

In addition to exposing 6 QMP commands for use by qemu-img (add,
remove, clear, enable, disable, merge), this also has to export three
previously-static functions for use by blockdev.c transactions.

Signed-off-by: Eric Blake <eblake@redhat.com>
---
 Makefile.objs             |   2 +-
 include/sysemu/blockdev.h |  14 ++
 blockbitmaps.c            | 324 ++++++++++++++++++++++++++++++++++++++
 blockdev.c                | 293 ----------------------------------
 MAINTAINERS               |   1 +
 5 files changed, 340 insertions(+), 294 deletions(-)
 create mode 100644 blockbitmaps.c

diff --git a/Makefile.objs b/Makefile.objs
index a7c967633acf..44e30fa9a6e3 100644
--- a/Makefile.objs
+++ b/Makefile.objs
@@ -14,7 +14,7 @@ chardev-obj-y = chardev/
 authz-obj-y = authz/

 block-obj-y = nbd/
-block-obj-y += block.o blockjob.o job.o
+block-obj-y += block.o blockbitmaps.o blockjob.o job.o
 block-obj-y += block/ scsi/
 block-obj-y += qemu-io-cmds.o
 block-obj-$(CONFIG_REPLICATION) += replication.o
diff --git a/include/sysemu/blockdev.h b/include/sysemu/blockdev.h
index a86d99b3d875..523b7493b1cd 100644
--- a/include/sysemu/blockdev.h
+++ b/include/sysemu/blockdev.h
@@ -57,4 +57,18 @@ QemuOpts *drive_add(BlockInterfaceType type, int index, const char *file,
 DriveInfo *drive_new(QemuOpts *arg, BlockInterfaceType block_default_type,
                      Error **errp);

+BdrvDirtyBitmap *block_dirty_bitmap_lookup(const char *node,
+                                           const char *name,
+                                           BlockDriverState **pbs,
+                                           Error **errp);
+BdrvDirtyBitmap *do_block_dirty_bitmap_remove(const char *node,
+                                              const char *name, bool release,
+                                              BlockDriverState **bitmap_bs,
+                                              Error **errp);
+BdrvDirtyBitmap *do_block_dirty_bitmap_merge(const char *node,
+                                             const char *target,
+                                             BlockDirtyBitmapMergeSourceList *bitmaps,
+                                             HBitmap **backup, Error **errp);
+
+
 #endif
diff --git a/blockbitmaps.c b/blockbitmaps.c
new file mode 100644
index 000000000000..fea80efcd03a
--- /dev/null
+++ b/blockbitmaps.c
@@ -0,0 +1,324 @@
+/*
+ * QEMU host block device bitmaps
+ *
+ * Copyright (c) 2003-2008 Fabrice Bellard
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or
+ * later.  See the COPYING file in the top-level directory.
+ *
+ * This file incorporates work covered by the following copyright and
+ * permission notice:
+ *
+ * Copyright (c) 2003-2008 Fabrice Bellard
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include "qemu/osdep.h"
+
+#include "sysemu/blockdev.h"
+#include "block/block.h"
+#include "block/block_int.h"
+#include "qapi/qapi-commands-block.h"
+#include "qapi/error.h"
+
+/**
+ * block_dirty_bitmap_lookup:
+ * Return a dirty bitmap (if present), after validating
+ * the node reference and bitmap names.
+ *
+ * @node: The name of the BDS node to search for bitmaps
+ * @name: The name of the bitmap to search for
+ * @pbs: Output pointer for BDS lookup, if desired. Can be NULL.
+ * @errp: Output pointer for error information. Can be NULL.
+ *
+ * @return: A bitmap object on success, or NULL on failure.
+ */
+BdrvDirtyBitmap *block_dirty_bitmap_lookup(const char *node,
+                                           const char *name,
+                                           BlockDriverState **pbs,
+                                           Error **errp)
+{
+    BlockDriverState *bs;
+    BdrvDirtyBitmap *bitmap;
+
+    if (!node) {
+        error_setg(errp, "Node cannot be NULL");
+        return NULL;
+    }
+    if (!name) {
+        error_setg(errp, "Bitmap name cannot be NULL");
+        return NULL;
+    }
+    bs = bdrv_lookup_bs(node, node, NULL);
+    if (!bs) {
+        error_setg(errp, "Node '%s' not found", node);
+        return NULL;
+    }
+
+    bitmap = bdrv_find_dirty_bitmap(bs, name);
+    if (!bitmap) {
+        error_setg(errp, "Dirty bitmap '%s' not found", name);
+        return NULL;
+    }
+
+    if (pbs) {
+        *pbs = bs;
+    }
+
+    return bitmap;
+}
+
+void qmp_block_dirty_bitmap_add(const char *node, const char *name,
+                                bool has_granularity, uint32_t granularity,
+                                bool has_persistent, bool persistent,
+                                bool has_disabled, bool disabled,
+                                Error **errp)
+{
+    BlockDriverState *bs;
+    BdrvDirtyBitmap *bitmap;
+    AioContext *aio_context;
+
+    if (!name || name[0] == '\0') {
+        error_setg(errp, "Bitmap name cannot be empty");
+        return;
+    }
+
+    bs = bdrv_lookup_bs(node, node, errp);
+    if (!bs) {
+        return;
+    }
+
+    aio_context = bdrv_get_aio_context(bs);
+    aio_context_acquire(aio_context);
+
+    if (has_granularity) {
+        if (granularity < 512 || !is_power_of_2(granularity)) {
+            error_setg(errp, "Granularity must be power of 2 "
+                             "and at least 512");
+            goto out;
+        }
+    } else {
+        /* Default to cluster size, if available: */
+        granularity = bdrv_get_default_bitmap_granularity(bs);
+    }
+
+    if (!has_persistent) {
+        persistent = false;
+    }
+
+    if (!has_disabled) {
+        disabled = false;
+    }
+
+    if (persistent &&
+        !bdrv_can_store_new_dirty_bitmap(bs, name, granularity, errp))
+    {
+        goto out;
+    }
+
+    bitmap = bdrv_create_dirty_bitmap(bs, granularity, name, errp);
+    if (bitmap == NULL) {
+        goto out;
+    }
+
+    if (disabled) {
+        bdrv_disable_dirty_bitmap(bitmap);
+    }
+
+    bdrv_dirty_bitmap_set_persistence(bitmap, persistent);
+
+out:
+    aio_context_release(aio_context);
+}
+
+BdrvDirtyBitmap *do_block_dirty_bitmap_remove(const char *node,
+                                              const char *name, bool release,
+                                              BlockDriverState **bitmap_bs,
+                                              Error **errp)
+{
+    BlockDriverState *bs;
+    BdrvDirtyBitmap *bitmap;
+    AioContext *aio_context;
+
+    bitmap = block_dirty_bitmap_lookup(node, name, &bs, errp);
+    if (!bitmap || !bs) {
+        return NULL;
+    }
+
+    aio_context = bdrv_get_aio_context(bs);
+    aio_context_acquire(aio_context);
+
+    if (bdrv_dirty_bitmap_check(bitmap, BDRV_BITMAP_BUSY | BDRV_BITMAP_RO,
+                                errp)) {
+        aio_context_release(aio_context);
+        return NULL;
+    }
+
+    if (bdrv_dirty_bitmap_get_persistence(bitmap) &&
+        bdrv_remove_persistent_dirty_bitmap(bs, name, errp) < 0)
+    {
+        aio_context_release(aio_context);
+        return NULL;
+    }
+
+    if (release) {
+        bdrv_release_dirty_bitmap(bitmap);
+    }
+
+    if (bitmap_bs) {
+        *bitmap_bs = bs;
+    }
+
+    aio_context_release(aio_context);
+    return release ? NULL : bitmap;
+}
+
+void qmp_block_dirty_bitmap_remove(const char *node, const char *name,
+                                   Error **errp)
+{
+    do_block_dirty_bitmap_remove(node, name, true, NULL, errp);
+}
+
+/**
+ * Completely clear a bitmap, for the purposes of synchronizing a bitmap
+ * immediately after a full backup operation.
+ */
+void qmp_block_dirty_bitmap_clear(const char *node, const char *name,
+                                  Error **errp)
+{
+    BdrvDirtyBitmap *bitmap;
+    BlockDriverState *bs;
+
+    bitmap = block_dirty_bitmap_lookup(node, name, &bs, errp);
+    if (!bitmap || !bs) {
+        return;
+    }
+
+    if (bdrv_dirty_bitmap_check(bitmap, BDRV_BITMAP_DEFAULT, errp)) {
+        return;
+    }
+
+    bdrv_clear_dirty_bitmap(bitmap, NULL);
+}
+
+void qmp_block_dirty_bitmap_enable(const char *node, const char *name,
+                                   Error **errp)
+{
+    BlockDriverState *bs;
+    BdrvDirtyBitmap *bitmap;
+
+    bitmap = block_dirty_bitmap_lookup(node, name, &bs, errp);
+    if (!bitmap) {
+        return;
+    }
+
+    if (bdrv_dirty_bitmap_check(bitmap, BDRV_BITMAP_ALLOW_RO, errp)) {
+        return;
+    }
+
+    bdrv_enable_dirty_bitmap(bitmap);
+}
+
+void qmp_block_dirty_bitmap_disable(const char *node, const char *name,
+                                    Error **errp)
+{
+    BlockDriverState *bs;
+    BdrvDirtyBitmap *bitmap;
+
+    bitmap = block_dirty_bitmap_lookup(node, name, &bs, errp);
+    if (!bitmap) {
+        return;
+    }
+
+    if (bdrv_dirty_bitmap_check(bitmap, BDRV_BITMAP_ALLOW_RO, errp)) {
+        return;
+    }
+
+    bdrv_disable_dirty_bitmap(bitmap);
+}
+
+BdrvDirtyBitmap *do_block_dirty_bitmap_merge(
+        const char *node, const char *target,
+        BlockDirtyBitmapMergeSourceList *bitmaps,
+        HBitmap **backup, Error **errp)
+{
+    BlockDriverState *bs;
+    BdrvDirtyBitmap *dst, *src, *anon;
+    BlockDirtyBitmapMergeSourceList *lst;
+    Error *local_err = NULL;
+
+    dst = block_dirty_bitmap_lookup(node, target, &bs, errp);
+    if (!dst) {
+        return NULL;
+    }
+
+    anon = bdrv_create_dirty_bitmap(bs, bdrv_dirty_bitmap_granularity(dst),
+                                    NULL, errp);
+    if (!anon) {
+        return NULL;
+    }
+
+    for (lst = bitmaps; lst; lst = lst->next) {
+        switch (lst->value->type) {
+            const char *name, *node;
+        case QTYPE_QSTRING:
+            name = lst->value->u.local;
+            src = bdrv_find_dirty_bitmap(bs, name);
+            if (!src) {
+                error_setg(errp, "Dirty bitmap '%s' not found", name);
+                dst = NULL;
+                goto out;
+            }
+            break;
+        case QTYPE_QDICT:
+            node = lst->value->u.external.node;
+            name = lst->value->u.external.name;
+            src = block_dirty_bitmap_lookup(node, name, NULL, errp);
+            if (!src) {
+                dst = NULL;
+                goto out;
+            }
+            break;
+        default:
+            abort();
+        }
+
+        bdrv_merge_dirty_bitmap(anon, src, NULL, &local_err);
+        if (local_err) {
+            error_propagate(errp, local_err);
+            dst = NULL;
+            goto out;
+        }
+    }
+
+    /* Merge into dst; dst is unchanged on failure. */
+    bdrv_merge_dirty_bitmap(dst, anon, backup, errp);
+
+ out:
+    bdrv_release_dirty_bitmap(anon);
+    return dst;
+}
+
+void qmp_block_dirty_bitmap_merge(const char *node, const char *target,
+                                  BlockDirtyBitmapMergeSourceList *bitmaps,
+                                  Error **errp)
+{
+    do_block_dirty_bitmap_merge(node, target, bitmaps, NULL, errp);
+}
diff --git a/blockdev.c b/blockdev.c
index 5faddaa7052f..d4efd4cbf2cb 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -1185,53 +1185,6 @@ out_aio_context:
     return NULL;
 }

-/**
- * block_dirty_bitmap_lookup:
- * Return a dirty bitmap (if present), after validating
- * the node reference and bitmap names.
- *
- * @node: The name of the BDS node to search for bitmaps
- * @name: The name of the bitmap to search for
- * @pbs: Output pointer for BDS lookup, if desired. Can be NULL.
- * @errp: Output pointer for error information. Can be NULL.
- *
- * @return: A bitmap object on success, or NULL on failure.
- */
-static BdrvDirtyBitmap *block_dirty_bitmap_lookup(const char *node,
-                                                  const char *name,
-                                                  BlockDriverState **pbs,
-                                                  Error **errp)
-{
-    BlockDriverState *bs;
-    BdrvDirtyBitmap *bitmap;
-
-    if (!node) {
-        error_setg(errp, "Node cannot be NULL");
-        return NULL;
-    }
-    if (!name) {
-        error_setg(errp, "Bitmap name cannot be NULL");
-        return NULL;
-    }
-    bs = bdrv_lookup_bs(node, node, NULL);
-    if (!bs) {
-        error_setg(errp, "Node '%s' not found", node);
-        return NULL;
-    }
-
-    bitmap = bdrv_find_dirty_bitmap(bs, name);
-    if (!bitmap) {
-        error_setg(errp, "Dirty bitmap '%s' not found", name);
-        return NULL;
-    }
-
-    if (pbs) {
-        *pbs = bs;
-    }
-
-    return bitmap;
-}
-
 /* New and old BlockDriverState structs for atomic group operations */

 typedef struct BlkActionState BlkActionState;
@@ -2171,11 +2124,6 @@ static void block_dirty_bitmap_disable_abort(BlkActionState *common)
     }
 }

-static BdrvDirtyBitmap *do_block_dirty_bitmap_merge(
-        const char *node, const char *target,
-        BlockDirtyBitmapMergeSourceList *bitmaps,
-        HBitmap **backup, Error **errp);
-
 static void block_dirty_bitmap_merge_prepare(BlkActionState *common,
                                              Error **errp)
 {
@@ -2194,10 +2142,6 @@ static void block_dirty_bitmap_merge_prepare(BlkActionState *common,
                                                 errp);
 }

-static BdrvDirtyBitmap *do_block_dirty_bitmap_remove(
-        const char *node, const char *name, bool release,
-        BlockDriverState **bitmap_bs, Error **errp);
-
 static void block_dirty_bitmap_remove_prepare(BlkActionState *common,
                                               Error **errp)
 {
@@ -2441,243 +2385,6 @@ void qmp_block_passwd(bool has_device, const char *device,
                "Setting block passwords directly is no longer supported");
 }

-void qmp_block_dirty_bitmap_add(const char *node, const char *name,
-                                bool has_granularity, uint32_t granularity,
-                                bool has_persistent, bool persistent,
-                                bool has_disabled, bool disabled,
-                                Error **errp)
-{
-    BlockDriverState *bs;
-    BdrvDirtyBitmap *bitmap;
-    AioContext *aio_context;
-
-    if (!name || name[0] == '\0') {
-        error_setg(errp, "Bitmap name cannot be empty");
-        return;
-    }
-
-    bs = bdrv_lookup_bs(node, node, errp);
-    if (!bs) {
-        return;
-    }
-
-    aio_context = bdrv_get_aio_context(bs);
-    aio_context_acquire(aio_context);
-
-    if (has_granularity) {
-        if (granularity < 512 || !is_power_of_2(granularity)) {
-            error_setg(errp, "Granularity must be power of 2 "
-                             "and at least 512");
-            goto out;
-        }
-    } else {
-        /* Default to cluster size, if available: */
-        granularity = bdrv_get_default_bitmap_granularity(bs);
-    }
-
-    if (!has_persistent) {
-        persistent = false;
-    }
-
-    if (!has_disabled) {
-        disabled = false;
-    }
-
-    if (persistent &&
-        !bdrv_can_store_new_dirty_bitmap(bs, name, granularity, errp))
-    {
-        goto out;
-    }
-
-    bitmap = bdrv_create_dirty_bitmap(bs, granularity, name, errp);
-    if (bitmap == NULL) {
-        goto out;
-    }
-
-    if (disabled) {
-        bdrv_disable_dirty_bitmap(bitmap);
-    }
-
-    bdrv_dirty_bitmap_set_persistence(bitmap, persistent);
-
-out:
-    aio_context_release(aio_context);
-}
-
-static BdrvDirtyBitmap *do_block_dirty_bitmap_remove(
-        const char *node, const char *name, bool release,
-        BlockDriverState **bitmap_bs, Error **errp)
-{
-    BlockDriverState *bs;
-    BdrvDirtyBitmap *bitmap;
-    AioContext *aio_context;
-
-    bitmap = block_dirty_bitmap_lookup(node, name, &bs, errp);
-    if (!bitmap || !bs) {
-        return NULL;
-    }
-
-    aio_context = bdrv_get_aio_context(bs);
-    aio_context_acquire(aio_context);
-
-    if (bdrv_dirty_bitmap_check(bitmap, BDRV_BITMAP_BUSY | BDRV_BITMAP_RO,
-                                errp)) {
-        aio_context_release(aio_context);
-        return NULL;
-    }
-
-    if (bdrv_dirty_bitmap_get_persistence(bitmap) &&
-        bdrv_remove_persistent_dirty_bitmap(bs, name, errp) < 0)
-    {
-        aio_context_release(aio_context);
-        return NULL;
-    }
-
-    if (release) {
-        bdrv_release_dirty_bitmap(bitmap);
-    }
-
-    if (bitmap_bs) {
-        *bitmap_bs = bs;
-    }
-
-    aio_context_release(aio_context);
-    return release ? NULL : bitmap;
-}
-
-void qmp_block_dirty_bitmap_remove(const char *node, const char *name,
-                                   Error **errp)
-{
-    do_block_dirty_bitmap_remove(node, name, true, NULL, errp);
-}
-
-/**
- * Completely clear a bitmap, for the purposes of synchronizing a bitmap
- * immediately after a full backup operation.
- */
-void qmp_block_dirty_bitmap_clear(const char *node, const char *name,
-                                  Error **errp)
-{
-    BdrvDirtyBitmap *bitmap;
-    BlockDriverState *bs;
-
-    bitmap = block_dirty_bitmap_lookup(node, name, &bs, errp);
-    if (!bitmap || !bs) {
-        return;
-    }
-
-    if (bdrv_dirty_bitmap_check(bitmap, BDRV_BITMAP_DEFAULT, errp)) {
-        return;
-    }
-
-    bdrv_clear_dirty_bitmap(bitmap, NULL);
-}
-
-void qmp_block_dirty_bitmap_enable(const char *node, const char *name,
-                                   Error **errp)
-{
-    BlockDriverState *bs;
-    BdrvDirtyBitmap *bitmap;
-
-    bitmap = block_dirty_bitmap_lookup(node, name, &bs, errp);
-    if (!bitmap) {
-        return;
-    }
-
-    if (bdrv_dirty_bitmap_check(bitmap, BDRV_BITMAP_ALLOW_RO, errp)) {
-        return;
-    }
-
-    bdrv_enable_dirty_bitmap(bitmap);
-}
-
-void qmp_block_dirty_bitmap_disable(const char *node, const char *name,
-                                    Error **errp)
-{
-    BlockDriverState *bs;
-    BdrvDirtyBitmap *bitmap;
-
-    bitmap = block_dirty_bitmap_lookup(node, name, &bs, errp);
-    if (!bitmap) {
-        return;
-    }
-
-    if (bdrv_dirty_bitmap_check(bitmap, BDRV_BITMAP_ALLOW_RO, errp)) {
-        return;
-    }
-
-    bdrv_disable_dirty_bitmap(bitmap);
-}
-
-static BdrvDirtyBitmap *do_block_dirty_bitmap_merge(
-        const char *node, const char *target,
-        BlockDirtyBitmapMergeSourceList *bitmaps,
-        HBitmap **backup, Error **errp)
-{
-    BlockDriverState *bs;
-    BdrvDirtyBitmap *dst, *src, *anon;
-    BlockDirtyBitmapMergeSourceList *lst;
-    Error *local_err = NULL;
-
-    dst = block_dirty_bitmap_lookup(node, target, &bs, errp);
-    if (!dst) {
-        return NULL;
-    }
-
-    anon = bdrv_create_dirty_bitmap(bs, bdrv_dirty_bitmap_granularity(dst),
-                                    NULL, errp);
-    if (!anon) {
-        return NULL;
-    }
-
-    for (lst = bitmaps; lst; lst = lst->next) {
-        switch (lst->value->type) {
-            const char *name, *node;
-        case QTYPE_QSTRING:
-            name = lst->value->u.local;
-            src = bdrv_find_dirty_bitmap(bs, name);
-            if (!src) {
-                error_setg(errp, "Dirty bitmap '%s' not found", name);
-                dst = NULL;
-                goto out;
-            }
-            break;
-        case QTYPE_QDICT:
-            node = lst->value->u.external.node;
-            name = lst->value->u.external.name;
-            src = block_dirty_bitmap_lookup(node, name, NULL, errp);
-            if (!src) {
-                dst = NULL;
-                goto out;
-            }
-            break;
-        default:
-            abort();
-        }
-
-        bdrv_merge_dirty_bitmap(anon, src, NULL, &local_err);
-        if (local_err) {
-            error_propagate(errp, local_err);
-            dst = NULL;
-            goto out;
-        }
-    }
-
-    /* Merge into dst; dst is unchanged on failure. */
-    bdrv_merge_dirty_bitmap(dst, anon, backup, errp);
-
- out:
-    bdrv_release_dirty_bitmap(anon);
-    return dst;
-}
-
-void qmp_block_dirty_bitmap_merge(const char *node, const char *target,
-                                  BlockDirtyBitmapMergeSourceList *bitmaps,
-                                  Error **errp)
-{
-    do_block_dirty_bitmap_merge(node, target, bitmaps, NULL, errp);
-}
-
 BlockDirtyBitmapSha256 *qmp_x_debug_block_dirty_bitmap_sha256(const char *node,
                                                               const char *name,
                                                               Error **errp)
diff --git a/MAINTAINERS b/MAINTAINERS
index 8cbc1fac2bfc..769cd357d281 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -1989,6 +1989,7 @@ T: git https://github.com/jnsnow/qemu.git jobs
 Block QAPI, monitor, command line
 M: Markus Armbruster <armbru@redhat.com>
 S: Supported
+F: blockbitmaps.c
 F: blockdev.c
 F: blockdev-hmp-cmds.c
 F: block/qapi.c
-- 
2.26.2

On 21.04.20 23:20, Eric Blake wrote:
> Upcoming patches want to add some basic bitmap manipulation abilities
> to qemu-img.  But blockdev.o is too heavyweight to link into qemu-img
> (among other things, it would drag in block jobs and transaction
> support - qemu-img does offline manipulation, where atomicity is less
> important because there are no concurrent modifications to compete
> with), so it's time to split off the bare bones of what we will need
> into a new file blockbitmaps.o.
> 
> In addition to exposing 6 QMP commands for use by qemu-img (add,
> remove, clear, enable, disable, merge), this also has to export three
> previously-static functions for use by blockdev.c transactions.
> 
> Signed-off-by: Eric Blake <eblake@redhat.com>
> ---
>  Makefile.objs             |   2 +-
>  include/sysemu/blockdev.h |  14 ++
>  blockbitmaps.c            | 324 ++++++++++++++++++++++++++++++++++++++

Hm.  Can we get a better name?  blockdev-bitmaps.c, for example?

>  blockdev.c                | 293 ----------------------------------
>  MAINTAINERS               |   1 +
>  5 files changed, 340 insertions(+), 294 deletions(-)
>  create mode 100644 blockbitmaps.c

[...]

> diff --git a/include/sysemu/blockdev.h b/include/sysemu/blockdev.h
> index a86d99b3d875..523b7493b1cd 100644
> --- a/include/sysemu/blockdev.h
> +++ b/include/sysemu/blockdev.h
> @@ -57,4 +57,18 @@ QemuOpts *drive_add(BlockInterfaceType type, int index, const char *file,
>  DriveInfo *drive_new(QemuOpts *arg, BlockInterfaceType block_default_type,
>                       Error **errp);
> 
> +BdrvDirtyBitmap *block_dirty_bitmap_lookup(const char *node,
> +                                           const char *name,
> +                                           BlockDriverState **pbs,
> +                                           Error **errp);
> +BdrvDirtyBitmap *do_block_dirty_bitmap_remove(const char *node,
> +                                              const char *name, bool release,
> +                                              BlockDriverState **bitmap_bs,
> +                                              Error **errp);
> +BdrvDirtyBitmap *do_block_dirty_bitmap_merge(const char *node,
> +                                             const char *target,
> +                                             BlockDirtyBitmapMergeSourceList *bitmaps,
> +                                             HBitmap **backup, Error **errp);

Putting do_* functions into a normal header seems a bit weird.  Would
these fit better into block_int.h?

> +
>  #endif

[...]
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 8cbc1fac2bfc..769cd357d281 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -1989,6 +1989,7 @@ T: git https://github.com/jnsnow/qemu.git jobs
>  Block QAPI, monitor, command line
>  M: Markus Armbruster <armbru@redhat.com>
>  S: Supported
> +F: blockbitmaps.c

The natural choice for something split off of blockdev.c, but I wonder
if the Dirty Bitmaps section wouldn’t be a better fit.

Max

>  F: blockdev.c
>  F: blockdev-hmp-cmds.c
>  F: block/qapi.c
> 

On 4/30/20 8:59 AM, Max Reitz wrote:
> On 21.04.20 23:20, Eric Blake wrote:
>> Upcoming patches want to add some basic bitmap manipulation abilities
>> to qemu-img.  But blockdev.o is too heavyweight to link into qemu-img
>> (among other things, it would drag in block jobs and transaction
>> support - qemu-img does offline manipulation, where atomicity is less
>> important because there are no concurrent modifications to compete
>> with), so it's time to split off the bare bones of what we will need
>> into a new file blockbitmaps.o.
>>
>> In addition to exposing 6 QMP commands for use by qemu-img (add,
>> remove, clear, enable, disable, merge), this also has to export three
>> previously-static functions for use by blockdev.c transactions.
>>
>> Signed-off-by: Eric Blake <eblake@redhat.com>
>> ---
>>   Makefile.objs             |   2 +-
>>   include/sysemu/blockdev.h |  14 ++
>>   blockbitmaps.c            | 324 ++++++++++++++++++++++++++++++++++++++
> 
> Hm.  Can we get a better name?  blockdev-bitmaps.c, for example?

Sure, I'm open to bike-shed suggestions.  I'd also _really_ love to make 
the new file NOT live in the top-level, but that's a harder task that 
I'm not sure how to do (it's easy to tweak Makefile.objs for another 
file in the same directory, but harder to see through the magic to 
figure out how to relocate things).

> 
>>   blockdev.c                | 293 ----------------------------------
>>   MAINTAINERS               |   1 +
>>   5 files changed, 340 insertions(+), 294 deletions(-)
>>   create mode 100644 blockbitmaps.c
> 
> [...]
> 
>> diff --git a/include/sysemu/blockdev.h b/include/sysemu/blockdev.h
>> index a86d99b3d875..523b7493b1cd 100644
>> --- a/include/sysemu/blockdev.h
>> +++ b/include/sysemu/blockdev.h
>> @@ -57,4 +57,18 @@ QemuOpts *drive_add(BlockInterfaceType type, int index, const char *file,
>>   DriveInfo *drive_new(QemuOpts *arg, BlockInterfaceType block_default_type,
>>                        Error **errp);
>>
>> +BdrvDirtyBitmap *block_dirty_bitmap_lookup(const char *node,
>> +                                           const char *name,
>> +                                           BlockDriverState **pbs,
>> +                                           Error **errp);
>> +BdrvDirtyBitmap *do_block_dirty_bitmap_remove(const char *node,
>> +                                              const char *name, bool release,
>> +                                              BlockDriverState **bitmap_bs,
>> +                                              Error **errp);
>> +BdrvDirtyBitmap *do_block_dirty_bitmap_merge(const char *node,
>> +                                             const char *target,
>> +                                             BlockDirtyBitmapMergeSourceList *bitmaps,
>> +                                             HBitmap **backup, Error **errp);
> 
> Putting do_* functions into a normal header seems a bit weird.  Would
> these fit better into block_int.h?

I don't care which header gets them, as long as things compile. 
block_int.h seems reasonable, so I can try that.  I also wonder if I 
should rename them at all (at which point, maybe I split this into two 
patches - one doing the rename, the other doing the file motion).


>> +++ b/MAINTAINERS
>> @@ -1989,6 +1989,7 @@ T: git https://github.com/jnsnow/qemu.git jobs
>>   Block QAPI, monitor, command line
>>   M: Markus Armbruster <armbru@redhat.com>
>>   S: Supported
>> +F: blockbitmaps.c
> 
> The natural choice for something split off of blockdev.c, but I wonder
> if the Dirty Bitmaps section wouldn’t be a better fit.

Or maybe even both?


-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3226
Virtualization:  qemu.org | libvirt.org

Am 30.04.2020 um 16:50 hat Eric Blake geschrieben:
> On 4/30/20 8:59 AM, Max Reitz wrote:
> > On 21.04.20 23:20, Eric Blake wrote:
> > > Upcoming patches want to add some basic bitmap manipulation abilities
> > > to qemu-img.  But blockdev.o is too heavyweight to link into qemu-img
> > > (among other things, it would drag in block jobs and transaction
> > > support - qemu-img does offline manipulation, where atomicity is less
> > > important because there are no concurrent modifications to compete
> > > with), so it's time to split off the bare bones of what we will need
> > > into a new file blockbitmaps.o.
> > > 
> > > In addition to exposing 6 QMP commands for use by qemu-img (add,
> > > remove, clear, enable, disable, merge), this also has to export three
> > > previously-static functions for use by blockdev.c transactions.
> > > 
> > > Signed-off-by: Eric Blake <eblake@redhat.com>
> > > ---
> > >   Makefile.objs             |   2 +-
> > >   include/sysemu/blockdev.h |  14 ++
> > >   blockbitmaps.c            | 324 ++++++++++++++++++++++++++++++++++++++
> > 
> > Hm.  Can we get a better name?  blockdev-bitmaps.c, for example?
> 
> Sure, I'm open to bike-shed suggestions.  I'd also _really_ love to make the
> new file NOT live in the top-level, but that's a harder task that I'm not
> sure how to do (it's easy to tweak Makefile.objs for another file in the
> same directory, but harder to see through the magic to figure out how to
> relocate things).

Yes, please move it somewhere else. I'd suggest something like
block/monitor/bitmap-qmp-cmds.c for the QMP command handlers, and if
there are functions that are more generally useful, block/bitmaps.c.

Instead of modifying the top-level Makefile.objs, you would just edit
block/monitor/Makefile.objs instead and add the filename there. I don't
think you need to understand any magic apart from knowing that is exists
and does what you would expect.

Kevin

On 5/8/20 6:37 AM, Kevin Wolf wrote:

>>>> ---
>>>>    Makefile.objs             |   2 +-
>>>>    include/sysemu/blockdev.h |  14 ++
>>>>    blockbitmaps.c            | 324 ++++++++++++++++++++++++++++++++++++++
>>>
>>> Hm.  Can we get a better name?  blockdev-bitmaps.c, for example?
>>
>> Sure, I'm open to bike-shed suggestions.  I'd also _really_ love to make the
>> new file NOT live in the top-level, but that's a harder task that I'm not
>> sure how to do (it's easy to tweak Makefile.objs for another file in the
>> same directory, but harder to see through the magic to figure out how to
>> relocate things).
> 
> Yes, please move it somewhere else. I'd suggest something like
> block/monitor/bitmap-qmp-cmds.c for the QMP command handlers, and if
> there are functions that are more generally useful, block/bitmaps.c.
> 
> Instead of modifying the top-level Makefile.objs, you would just edit
> block/monitor/Makefile.objs instead and add the filename there. I don't
> think you need to understand any magic apart from knowing that is exists
> and does what you would expect.

Well, you still have to modify the top-level Makefile.objs to tell it to 
look in the right subdirectories, but I got it figured out finally.  v3 
will use block/monitor/bitmap-qmp-cmds.c.

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3226
Virtualization:  qemu.org | libvirt.org