[PATCH v2 05/22] migration/block-dirty-bitmap: refactor state global variables

[Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>]

Move all state variables into one global struct. Reduce global
variable usage, utilizing opaque pointer where possible.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
---
 migration/block-dirty-bitmap.c | 171 ++++++++++++++++++---------------
 1 file changed, 95 insertions(+), 76 deletions(-)

diff --git a/migration/block-dirty-bitmap.c b/migration/block-dirty-bitmap.c
index 49d4cf8810..7a82b76809 100644
--- a/migration/block-dirty-bitmap.c
+++ b/migration/block-dirty-bitmap.c
@@ -128,6 +128,12 @@ typedef struct DBMSaveState {
     BdrvDirtyBitmap *prev_bitmap;
 } DBMSaveState;
 
+typedef struct LoadBitmapState {
+    BlockDriverState *bs;
+    BdrvDirtyBitmap *bitmap;
+    bool migrated;
+} LoadBitmapState;
+
 /* State of the dirty bitmap migration (DBM) during load process */
 typedef struct DBMLoadState {
     uint32_t flags;
@@ -135,18 +141,17 @@ typedef struct DBMLoadState {
     char bitmap_name[256];
     BlockDriverState *bs;
     BdrvDirtyBitmap *bitmap;
+
+    GSList *enabled_bitmaps;
+    QemuMutex finish_lock;
 } DBMLoadState;
 
-static DBMSaveState dirty_bitmap_mig_state;
+typedef struct DBMState {
+    DBMSaveState save;
+    DBMLoadState load;
+} DBMState;
 
-/* State of one bitmap during load process */
-typedef struct LoadBitmapState {
-    BlockDriverState *bs;
-    BdrvDirtyBitmap *bitmap;
-    bool migrated;
-} LoadBitmapState;
-static GSList *enabled_bitmaps;
-QemuMutex finish_lock;
+static DBMState dbm_state;
 
 static uint32_t qemu_get_bitmap_flags(QEMUFile *f)
 {
@@ -169,21 +174,21 @@ static void qemu_put_bitmap_flags(QEMUFile *f, uint32_t flags)
     qemu_put_byte(f, flags);
 }
 
-static void send_bitmap_header(QEMUFile *f, SaveBitmapState *dbms,
-                               uint32_t additional_flags)
+static void send_bitmap_header(QEMUFile *f, DBMSaveState *s,
+                               SaveBitmapState *dbms, uint32_t additional_flags)
 {
     BlockDriverState *bs = dbms->bs;
     BdrvDirtyBitmap *bitmap = dbms->bitmap;
     uint32_t flags = additional_flags;
     trace_send_bitmap_header_enter();
 
-    if (bs != dirty_bitmap_mig_state.prev_bs) {
-        dirty_bitmap_mig_state.prev_bs = bs;
+    if (bs != s->prev_bs) {
+        s->prev_bs = bs;
         flags |= DIRTY_BITMAP_MIG_FLAG_DEVICE_NAME;
     }
 
-    if (bitmap != dirty_bitmap_mig_state.prev_bitmap) {
-        dirty_bitmap_mig_state.prev_bitmap = bitmap;
+    if (bitmap != s->prev_bitmap) {
+        s->prev_bitmap = bitmap;
         flags |= DIRTY_BITMAP_MIG_FLAG_BITMAP_NAME;
     }
 
@@ -198,19 +203,22 @@ static void send_bitmap_header(QEMUFile *f, SaveBitmapState *dbms,
     }
 }
 
-static void send_bitmap_start(QEMUFile *f, SaveBitmapState *dbms)
+static void send_bitmap_start(QEMUFile *f, DBMSaveState *s,
+                              SaveBitmapState *dbms)
 {
-    send_bitmap_header(f, dbms, DIRTY_BITMAP_MIG_FLAG_START);
+    send_bitmap_header(f, s, dbms, DIRTY_BITMAP_MIG_FLAG_START);
     qemu_put_be32(f, bdrv_dirty_bitmap_granularity(dbms->bitmap));
     qemu_put_byte(f, dbms->flags);
 }
 
-static void send_bitmap_complete(QEMUFile *f, SaveBitmapState *dbms)
+static void send_bitmap_complete(QEMUFile *f, DBMSaveState *s,
+                                 SaveBitmapState *dbms)
 {
-    send_bitmap_header(f, dbms, DIRTY_BITMAP_MIG_FLAG_COMPLETE);
+    send_bitmap_header(f, s, dbms, DIRTY_BITMAP_MIG_FLAG_COMPLETE);
 }
 
-static void send_bitmap_bits(QEMUFile *f, SaveBitmapState *dbms,
+static void send_bitmap_bits(QEMUFile *f, DBMSaveState *s,
+                             SaveBitmapState *dbms,
                              uint64_t start_sector, uint32_t nr_sectors)
 {
     /* align for buffer_is_zero() */
@@ -235,7 +243,7 @@ static void send_bitmap_bits(QEMUFile *f, SaveBitmapState *dbms,
 
     trace_send_bitmap_bits(flags, start_sector, nr_sectors, buf_size);
 
-    send_bitmap_header(f, dbms, flags);
+    send_bitmap_header(f, s, dbms, flags);
 
     qemu_put_be64(f, start_sector);
     qemu_put_be32(f, nr_sectors);
@@ -254,12 +262,12 @@ static void send_bitmap_bits(QEMUFile *f, SaveBitmapState *dbms,
 }
 
 /* Called with iothread lock taken.  */
-static void dirty_bitmap_do_save_cleanup(void)
+static void dirty_bitmap_do_save_cleanup(DBMSaveState *s)
 {
     SaveBitmapState *dbms;
 
-    while ((dbms = QSIMPLEQ_FIRST(&dirty_bitmap_mig_state.dbms_list)) != NULL) {
-        QSIMPLEQ_REMOVE_HEAD(&dirty_bitmap_mig_state.dbms_list, entry);
+    while ((dbms = QSIMPLEQ_FIRST(&s->dbms_list)) != NULL) {
+        QSIMPLEQ_REMOVE_HEAD(&s->dbms_list, entry);
         bdrv_dirty_bitmap_set_busy(dbms->bitmap, false);
         bdrv_unref(dbms->bs);
         g_free(dbms);
@@ -267,17 +275,17 @@ static void dirty_bitmap_do_save_cleanup(void)
 }
 
 /* Called with iothread lock taken. */
-static int init_dirty_bitmap_migration(void)
+static int init_dirty_bitmap_migration(DBMSaveState *s)
 {
     BlockDriverState *bs;
     BdrvDirtyBitmap *bitmap;
     SaveBitmapState *dbms;
     Error *local_err = NULL;
 
-    dirty_bitmap_mig_state.bulk_completed = false;
-    dirty_bitmap_mig_state.prev_bs = NULL;
-    dirty_bitmap_mig_state.prev_bitmap = NULL;
-    dirty_bitmap_mig_state.no_bitmaps = false;
+    s->bulk_completed = false;
+    s->prev_bs = NULL;
+    s->prev_bitmap = NULL;
+    s->no_bitmaps = false;
 
     for (bs = bdrv_next_all_states(NULL); bs; bs = bdrv_next_all_states(bs)) {
         const char *name = bdrv_get_device_or_node_name(bs);
@@ -316,35 +324,36 @@ static int init_dirty_bitmap_migration(void)
                 dbms->flags |= DIRTY_BITMAP_MIG_START_FLAG_PERSISTENT;
             }
 
-            QSIMPLEQ_INSERT_TAIL(&dirty_bitmap_mig_state.dbms_list,
+            QSIMPLEQ_INSERT_TAIL(&s->dbms_list,
                                  dbms, entry);
         }
     }
 
     /* unset migration flags here, to not roll back it */
-    QSIMPLEQ_FOREACH(dbms, &dirty_bitmap_mig_state.dbms_list, entry) {
+    QSIMPLEQ_FOREACH(dbms, &s->dbms_list, entry) {
         bdrv_dirty_bitmap_skip_store(dbms->bitmap, true);
     }
 
-    if (QSIMPLEQ_EMPTY(&dirty_bitmap_mig_state.dbms_list)) {
-        dirty_bitmap_mig_state.no_bitmaps = true;
+    if (QSIMPLEQ_EMPTY(&s->dbms_list)) {
+        s->no_bitmaps = true;
     }
 
     return 0;
 
 fail:
-    dirty_bitmap_do_save_cleanup();
+    dirty_bitmap_do_save_cleanup(s);
 
     return -1;
 }
 
 /* Called with no lock taken.  */
-static void bulk_phase_send_chunk(QEMUFile *f, SaveBitmapState *dbms)
+static void bulk_phase_send_chunk(QEMUFile *f, DBMSaveState *s,
+                                  SaveBitmapState *dbms)
 {
     uint32_t nr_sectors = MIN(dbms->total_sectors - dbms->cur_sector,
                              dbms->sectors_per_chunk);
 
-    send_bitmap_bits(f, dbms, dbms->cur_sector, nr_sectors);
+    send_bitmap_bits(f, s, dbms, dbms->cur_sector, nr_sectors);
 
     dbms->cur_sector += nr_sectors;
     if (dbms->cur_sector >= dbms->total_sectors) {
@@ -353,61 +362,66 @@ static void bulk_phase_send_chunk(QEMUFile *f, SaveBitmapState *dbms)
 }
 
 /* Called with no lock taken.  */
-static void bulk_phase(QEMUFile *f, bool limit)
+static void bulk_phase(QEMUFile *f, DBMSaveState *s, bool limit)
 {
     SaveBitmapState *dbms;
 
-    QSIMPLEQ_FOREACH(dbms, &dirty_bitmap_mig_state.dbms_list, entry) {
+    QSIMPLEQ_FOREACH(dbms, &s->dbms_list, entry) {
         while (!dbms->bulk_completed) {
-            bulk_phase_send_chunk(f, dbms);
+            bulk_phase_send_chunk(f, s, dbms);
             if (limit && qemu_file_rate_limit(f)) {
                 return;
             }
         }
     }
 
-    dirty_bitmap_mig_state.bulk_completed = true;
+    s->bulk_completed = true;
 }
 
 /* for SaveVMHandlers */
 static void dirty_bitmap_save_cleanup(void *opaque)
 {
-    dirty_bitmap_do_save_cleanup();
+    DBMSaveState *s = &((DBMState *)opaque)->save;
+
+    dirty_bitmap_do_save_cleanup(s);
 }
 
 static int dirty_bitmap_save_iterate(QEMUFile *f, void *opaque)
 {
+    DBMSaveState *s = &((DBMState *)opaque)->save;
+
     trace_dirty_bitmap_save_iterate(migration_in_postcopy());
 
-    if (migration_in_postcopy() && !dirty_bitmap_mig_state.bulk_completed) {
-        bulk_phase(f, true);
+    if (migration_in_postcopy() && !s->bulk_completed) {
+        bulk_phase(f, s, true);
     }
 
     qemu_put_bitmap_flags(f, DIRTY_BITMAP_MIG_FLAG_EOS);
 
-    return dirty_bitmap_mig_state.bulk_completed;
+    return s->bulk_completed;
 }
 
 /* Called with iothread lock taken.  */
 
 static int dirty_bitmap_save_complete(QEMUFile *f, void *opaque)
 {
+    DBMSaveState *s = &((DBMState *)opaque)->save;
     SaveBitmapState *dbms;
     trace_dirty_bitmap_save_complete_enter();
 
-    if (!dirty_bitmap_mig_state.bulk_completed) {
-        bulk_phase(f, false);
+    if (!s->bulk_completed) {
+        bulk_phase(f, s, false);
     }
 
-    QSIMPLEQ_FOREACH(dbms, &dirty_bitmap_mig_state.dbms_list, entry) {
-        send_bitmap_complete(f, dbms);
+    QSIMPLEQ_FOREACH(dbms, &s->dbms_list, entry) {
+        send_bitmap_complete(f, s, dbms);
     }
 
     qemu_put_bitmap_flags(f, DIRTY_BITMAP_MIG_FLAG_EOS);
 
     trace_dirty_bitmap_save_complete_finish();
 
-    dirty_bitmap_do_save_cleanup();
+    dirty_bitmap_save_cleanup(opaque);
     return 0;
 }
 
@@ -417,12 +431,13 @@ static void dirty_bitmap_save_pending(QEMUFile *f, void *opaque,
                                       uint64_t *res_compatible,
                                       uint64_t *res_postcopy_only)
 {
+    DBMSaveState *s = &((DBMState *)opaque)->save;
     SaveBitmapState *dbms;
     uint64_t pending = 0;
 
     qemu_mutex_lock_iothread();
 
-    QSIMPLEQ_FOREACH(dbms, &dirty_bitmap_mig_state.dbms_list, entry) {
+    QSIMPLEQ_FOREACH(dbms, &s->dbms_list, entry) {
         uint64_t gran = bdrv_dirty_bitmap_granularity(dbms->bitmap);
         uint64_t sectors = dbms->bulk_completed ? 0 :
                            dbms->total_sectors - dbms->cur_sector;
@@ -481,7 +496,7 @@ static int dirty_bitmap_load_start(QEMUFile *f, DBMLoadState *s)
         b->bs = s->bs;
         b->bitmap = s->bitmap;
         b->migrated = false;
-        enabled_bitmaps = g_slist_prepend(enabled_bitmaps, b);
+        s->enabled_bitmaps = g_slist_prepend(s->enabled_bitmaps, b);
     }
 
     return 0;
@@ -489,11 +504,12 @@ static int dirty_bitmap_load_start(QEMUFile *f, DBMLoadState *s)
 
 void dirty_bitmap_mig_before_vm_start(void)
 {
+    DBMLoadState *s = &dbm_state.load;
     GSList *item;
 
-    qemu_mutex_lock(&finish_lock);
+    qemu_mutex_lock(&s->finish_lock);
 
-    for (item = enabled_bitmaps; item; item = g_slist_next(item)) {
+    for (item = s->enabled_bitmaps; item; item = g_slist_next(item)) {
         LoadBitmapState *b = item->data;
 
         if (b->migrated) {
@@ -505,10 +521,10 @@ void dirty_bitmap_mig_before_vm_start(void)
         g_free(b);
     }
 
-    g_slist_free(enabled_bitmaps);
-    enabled_bitmaps = NULL;
+    g_slist_free(s->enabled_bitmaps);
+    s->enabled_bitmaps = NULL;
 
-    qemu_mutex_unlock(&finish_lock);
+    qemu_mutex_unlock(&s->finish_lock);
 }
 
 static void dirty_bitmap_load_complete(QEMUFile *f, DBMLoadState *s)
@@ -517,9 +533,9 @@ static void dirty_bitmap_load_complete(QEMUFile *f, DBMLoadState *s)
     trace_dirty_bitmap_load_complete();
     bdrv_dirty_bitmap_deserialize_finish(s->bitmap);
 
-    qemu_mutex_lock(&finish_lock);
+    qemu_mutex_lock(&s->finish_lock);
 
-    for (item = enabled_bitmaps; item; item = g_slist_next(item)) {
+    for (item = s->enabled_bitmaps; item; item = g_slist_next(item)) {
         LoadBitmapState *b = item->data;
 
         if (b->bitmap == s->bitmap) {
@@ -530,7 +546,7 @@ static void dirty_bitmap_load_complete(QEMUFile *f, DBMLoadState *s)
 
     if (bdrv_dirty_bitmap_has_successor(s->bitmap)) {
         bdrv_dirty_bitmap_lock(s->bitmap);
-        if (enabled_bitmaps == NULL) {
+        if (s->enabled_bitmaps == NULL) {
             /* in postcopy */
             bdrv_reclaim_dirty_bitmap_locked(s->bitmap, &error_abort);
             bdrv_enable_dirty_bitmap_locked(s->bitmap);
@@ -549,7 +565,7 @@ static void dirty_bitmap_load_complete(QEMUFile *f, DBMLoadState *s)
         bdrv_dirty_bitmap_unlock(s->bitmap);
     }
 
-    qemu_mutex_unlock(&finish_lock);
+    qemu_mutex_unlock(&s->finish_lock);
 }
 
 static int dirty_bitmap_load_bits(QEMUFile *f, DBMLoadState *s)
@@ -646,7 +662,7 @@ static int dirty_bitmap_load_header(QEMUFile *f, DBMLoadState *s)
 
 static int dirty_bitmap_load(QEMUFile *f, void *opaque, int version_id)
 {
-    static DBMLoadState s;
+    DBMLoadState *s = &((DBMState *)opaque)->load;
     int ret = 0;
 
     trace_dirty_bitmap_load_enter();
@@ -656,17 +672,17 @@ static int dirty_bitmap_load(QEMUFile *f, void *opaque, int version_id)
     }
 
     do {
-        ret = dirty_bitmap_load_header(f, &s);
+        ret = dirty_bitmap_load_header(f, s);
         if (ret < 0) {
             return ret;
         }
 
-        if (s.flags & DIRTY_BITMAP_MIG_FLAG_START) {
-            ret = dirty_bitmap_load_start(f, &s);
-        } else if (s.flags & DIRTY_BITMAP_MIG_FLAG_COMPLETE) {
-            dirty_bitmap_load_complete(f, &s);
-        } else if (s.flags & DIRTY_BITMAP_MIG_FLAG_BITS) {
-            ret = dirty_bitmap_load_bits(f, &s);
+        if (s->flags & DIRTY_BITMAP_MIG_FLAG_START) {
+            ret = dirty_bitmap_load_start(f, s);
+        } else if (s->flags & DIRTY_BITMAP_MIG_FLAG_COMPLETE) {
+            dirty_bitmap_load_complete(f, s);
+        } else if (s->flags & DIRTY_BITMAP_MIG_FLAG_BITS) {
+            ret = dirty_bitmap_load_bits(f, s);
         }
 
         if (!ret) {
@@ -676,7 +692,7 @@ static int dirty_bitmap_load(QEMUFile *f, void *opaque, int version_id)
         if (ret) {
             return ret;
         }
-    } while (!(s.flags & DIRTY_BITMAP_MIG_FLAG_EOS));
+    } while (!(s->flags & DIRTY_BITMAP_MIG_FLAG_EOS));
 
     trace_dirty_bitmap_load_success();
     return 0;
@@ -684,13 +700,14 @@ static int dirty_bitmap_load(QEMUFile *f, void *opaque, int version_id)
 
 static int dirty_bitmap_save_setup(QEMUFile *f, void *opaque)
 {
+    DBMSaveState *s = &((DBMState *)opaque)->save;
     SaveBitmapState *dbms = NULL;
-    if (init_dirty_bitmap_migration() < 0) {
+    if (init_dirty_bitmap_migration(s) < 0) {
         return -1;
     }
 
-    QSIMPLEQ_FOREACH(dbms, &dirty_bitmap_mig_state.dbms_list, entry) {
-        send_bitmap_start(f, dbms);
+    QSIMPLEQ_FOREACH(dbms, &s->dbms_list, entry) {
+        send_bitmap_start(f, s, dbms);
     }
     qemu_put_bitmap_flags(f, DIRTY_BITMAP_MIG_FLAG_EOS);
 
@@ -699,7 +716,9 @@ static int dirty_bitmap_save_setup(QEMUFile *f, void *opaque)
 
 static bool dirty_bitmap_is_active(void *opaque)
 {
-    return migrate_dirty_bitmaps() && !dirty_bitmap_mig_state.no_bitmaps;
+    DBMSaveState *s = &((DBMState *)opaque)->save;
+
+    return migrate_dirty_bitmaps() && !s->no_bitmaps;
 }
 
 static bool dirty_bitmap_is_active_iterate(void *opaque)
@@ -727,10 +746,10 @@ static SaveVMHandlers savevm_dirty_bitmap_handlers = {
 
 void dirty_bitmap_mig_init(void)
 {
-    QSIMPLEQ_INIT(&dirty_bitmap_mig_state.dbms_list);
-    qemu_mutex_init(&finish_lock);
+    QSIMPLEQ_INIT(&dbm_state.save.dbms_list);
+    qemu_mutex_init(&dbm_state.load.finish_lock);
 
     register_savevm_live("dirty-bitmap", 0, 1,
                          &savevm_dirty_bitmap_handlers,
-                         &dirty_bitmap_mig_state);
+                         &dbm_state);
 }
-- 
2.21.0