diff mbox series

[1/7] migration/block-dirty-bitmap: refactor incoming state to be one struct

Message ID 20200122132328.31156-2-vsementsov@virtuozzo.com
State New
Headers show
Series Fix crashes on early shutdown during bitmaps postcopy | expand

Commit Message

Vladimir Sementsov-Ogievskiy Jan. 22, 2020, 1:23 p.m. UTC 
Move enabled_bitmaps and finish_lock, which are part of incoming state
to DirtyBitmapLoadState, and make static global variable to store state
instead of static local one.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
---
 migration/block-dirty-bitmap.c | 77 +++++++++++++++++++---------------
 1 file changed, 43 insertions(+), 34 deletions(-)

Comments

Juan Quintela Jan. 24, 2020, 10:56 a.m. UTC | #1 
Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> wrote:
> Move enabled_bitmaps and finish_lock, which are part of incoming state
> to DirtyBitmapLoadState, and make static global variable to store state
> instead of static local one.
>
> Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
> ---
>  migration/block-dirty-bitmap.c | 77 +++++++++++++++++++---------------
>  1 file changed, 43 insertions(+), 34 deletions(-)
>
> diff --git a/migration/block-dirty-bitmap.c b/migration/block-dirty-bitmap.c
> index 7eafface61..281d20f41d 100644
> --- a/migration/block-dirty-bitmap.c
> +++ b/migration/block-dirty-bitmap.c
> @@ -125,6 +125,13 @@ typedef struct DirtyBitmapMigState {
>      BlockDriverState *prev_bs;
>      BdrvDirtyBitmap *prev_bitmap;
>  } DirtyBitmapMigState;
> +static DirtyBitmapMigState dirty_bitmap_mig_state;

Missing new line.

> +
> +typedef struct DirtyBitmapLoadBitmapState {
> +    BlockDriverState *bs;
> +    BdrvDirtyBitmap *bitmap;
> +    bool migrated;
> +} DirtyBitmapLoadBitmapState;
>  
>  typedef struct DirtyBitmapLoadState {
>      uint32_t flags;
> @@ -132,21 +139,15 @@ typedef struct DirtyBitmapLoadState {
>      char bitmap_name[256];
>      BlockDriverState *bs;
>      BdrvDirtyBitmap *bitmap;
> -} DirtyBitmapLoadState;
>  
> -static DirtyBitmapMigState dirty_bitmap_mig_state;
> -
> -typedef struct DirtyBitmapLoadBitmapState {
> -    BlockDriverState *bs;
> -    BdrvDirtyBitmap *bitmap;
> -    bool migrated;
> -} DirtyBitmapLoadBitmapState;
> -static GSList *enabled_bitmaps;
> -QemuMutex finish_lock;
> +    GSList *enabled_bitmaps;
> +    QemuMutex finish_lock;
> +} DirtyBitmapLoadState;
> +static DirtyBitmapLoadState dbm_load_state;

You move two global variables to an struct (good)
But you create a even bigger global variable (i.e. state that was not
shared before.)

>  /* First occurrence of this bitmap. It should be created if doesn't exist */
> -static int dirty_bitmap_load_start(QEMUFile *f, DirtyBitmapLoadState *s)
> +static int dirty_bitmap_load_start(QEMUFile *f)
>  {
> +    DirtyBitmapLoadState *s = &dbm_load_state;

You create a local alias.

>      Error *local_err = NULL;
>      uint32_t granularity = qemu_get_be32(f);
>      uint8_t flags = qemu_get_byte(f);
> @@ -482,7 +484,8 @@ static int dirty_bitmap_load_start(QEMUFile *f, DirtyBitmapLoadState *s)
>          b->bs = s->bs;
>          b->bitmap = s->bitmap;
>          b->migrated = false;
> -        enabled_bitmaps = g_slist_prepend(enabled_bitmaps, b);
> +        dbm_load_state.enabled_bitmaps =
> +            g_slist_prepend(dbm_load_state.enabled_bitmaps, b);

And then you access it using the global variable?

> -static void dirty_bitmap_load_complete(QEMUFile *f, DirtyBitmapLoadState *s)
> +static void dirty_bitmap_load_complete(QEMUFile *f)
>  {
> +    DirtyBitmapLoadState *s = &dbm_load_state;

Exactly the same on this function.

I still don't understand why you are removing the pass as parameters of
this function.


> -    static DirtyBitmapLoadState s;

Aha, this is why you are moving it as a global.

But, why can't you put this inside dirty_bitmap_mig_state?  Then you:
a- don't have to have "yet" another global variable
b- you can clean it up on save_cleanup handler.

not related to this patch, but to the file in general:

static void dirty_bitmap_save_cleanup(void *opaque)
{
    dirty_bitmap_mig_cleanup();
}

We have opaque here, that we can do:

DirtyBitmapMigBitmapState *dbms = opaque;

And then pass dbms to dirty_bitmap_mig_cleanup().

/* Called with iothread lock taken.  */
static void dirty_bitmap_mig_cleanup(void)
{
    DirtyBitmapMigBitmapState *dbms;

    while ((dbms = QSIMPLEQ_FIRST(&dirty_bitmap_mig_state.dbms_list)) != NULL) {
        QSIMPLEQ_REMOVE_HEAD(&dirty_bitmap_mig_state.dbms_list, entry);
        bdrv_dirty_bitmap_set_busy(dbms->bitmap, false);
        bdrv_unref(dbms->bs);
        g_free(dbms);
    }
}


Because here we just use the global variable.

Later, Juan.
Vladimir Sementsov-Ogievskiy Feb. 11, 2020, 3:03 p.m. UTC | #2 
24.01.2020 13:56, Juan Quintela wrote:
> Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> wrote:
>> Move enabled_bitmaps and finish_lock, which are part of incoming state
>> to DirtyBitmapLoadState, and make static global variable to store state
>> instead of static local one.
>>
>> Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
>> ---
>>   migration/block-dirty-bitmap.c | 77 +++++++++++++++++++---------------
>>   1 file changed, 43 insertions(+), 34 deletions(-)
>>
>> diff --git a/migration/block-dirty-bitmap.c b/migration/block-dirty-bitmap.c
>> index 7eafface61..281d20f41d 100644
>> --- a/migration/block-dirty-bitmap.c
>> +++ b/migration/block-dirty-bitmap.c
>> @@ -125,6 +125,13 @@ typedef struct DirtyBitmapMigState {
>>       BlockDriverState *prev_bs;
>>       BdrvDirtyBitmap *prev_bitmap;
>>   } DirtyBitmapMigState;
>> +static DirtyBitmapMigState dirty_bitmap_mig_state;
> 
> Missing new line.
> 
>> +
>> +typedef struct DirtyBitmapLoadBitmapState {
>> +    BlockDriverState *bs;
>> +    BdrvDirtyBitmap *bitmap;
>> +    bool migrated;
>> +} DirtyBitmapLoadBitmapState;
>>   
>>   typedef struct DirtyBitmapLoadState {
>>       uint32_t flags;
>> @@ -132,21 +139,15 @@ typedef struct DirtyBitmapLoadState {
>>       char bitmap_name[256];
>>       BlockDriverState *bs;
>>       BdrvDirtyBitmap *bitmap;
>> -} DirtyBitmapLoadState;
>>   
>> -static DirtyBitmapMigState dirty_bitmap_mig_state;
>> -
>> -typedef struct DirtyBitmapLoadBitmapState {
>> -    BlockDriverState *bs;
>> -    BdrvDirtyBitmap *bitmap;
>> -    bool migrated;
>> -} DirtyBitmapLoadBitmapState;
>> -static GSList *enabled_bitmaps;
>> -QemuMutex finish_lock;
>> +    GSList *enabled_bitmaps;
>> +    QemuMutex finish_lock;
>> +} DirtyBitmapLoadState;
>> +static DirtyBitmapLoadState dbm_load_state;
> 
> You move two global variables to an struct (good)
> But you create a even bigger global variable (i.e. state that was not
> shared before.)
> 
>>   /* First occurrence of this bitmap. It should be created if doesn't exist */
>> -static int dirty_bitmap_load_start(QEMUFile *f, DirtyBitmapLoadState *s)
>> +static int dirty_bitmap_load_start(QEMUFile *f)
>>   {
>> +    DirtyBitmapLoadState *s = &dbm_load_state;
> 
> You create a local alias.
> 
>>       Error *local_err = NULL;
>>       uint32_t granularity = qemu_get_be32(f);
>>       uint8_t flags = qemu_get_byte(f);
>> @@ -482,7 +484,8 @@ static int dirty_bitmap_load_start(QEMUFile *f, DirtyBitmapLoadState *s)
>>           b->bs = s->bs;
>>           b->bitmap = s->bitmap;
>>           b->migrated = false;
>> -        enabled_bitmaps = g_slist_prepend(enabled_bitmaps, b);
>> +        dbm_load_state.enabled_bitmaps =
>> +            g_slist_prepend(dbm_load_state.enabled_bitmaps, b);
> 
> And then you access it using the global variable?
> 
>> -static void dirty_bitmap_load_complete(QEMUFile *f, DirtyBitmapLoadState *s)
>> +static void dirty_bitmap_load_complete(QEMUFile *f)
>>   {
>> +    DirtyBitmapLoadState *s = &dbm_load_state;
> 
> Exactly the same on this function.
> 
> I still don't understand why you are removing the pass as parameters of
> this function.
> 
> 
>> -    static DirtyBitmapLoadState s;
> 
> Aha, this is why you are moving it as a global.
> 
> But, why can't you put this inside dirty_bitmap_mig_state?  Then you:
> a- don't have to have "yet" another global variable
> b- you can clean it up on save_cleanup handler.

Because dirty_bitmap_mig_state is source state, and new dbm_load_state is
destination state. So, at least [b] will not work...

Do you think it's good to combine both source and destination states into one
struct, and use opaque everywhere?

It will look like

DirtyBitmapMigSourceState *s = ((DirtyBitmapMigState *)opaque)->source_state;

in save functions

and
DirtyBitmapIncomingState *s = ((DirtyBitmapMigState *)opaque)->incoming_state;

in load function

> 
> not related to this patch, but to the file in general:
> 
> static void dirty_bitmap_save_cleanup(void *opaque)
> {
>      dirty_bitmap_mig_cleanup();
> }
> 
> We have opaque here, that we can do:
> 
> DirtyBitmapMigBitmapState *dbms = opaque;
> 
> And then pass dbms to dirty_bitmap_mig_cleanup().
> 
> /* Called with iothread lock taken.  */
> static void dirty_bitmap_mig_cleanup(void)
> {
>      DirtyBitmapMigBitmapState *dbms;
> 
>      while ((dbms = QSIMPLEQ_FIRST(&dirty_bitmap_mig_state.dbms_list)) != NULL) {
>          QSIMPLEQ_REMOVE_HEAD(&dirty_bitmap_mig_state.dbms_list, entry);
>          bdrv_dirty_bitmap_set_busy(dbms->bitmap, false);
>          bdrv_unref(dbms->bs);
>          g_free(dbms);
>      }
> }
> 
> 
> Because here we just use the global variable.
> 
> Later, Juan.
>
diff mbox series

Patch

diff --git a/migration/block-dirty-bitmap.c b/migration/block-dirty-bitmap.c
index 7eafface61..281d20f41d 100644
--- a/migration/block-dirty-bitmap.c
+++ b/migration/block-dirty-bitmap.c
@@ -125,6 +125,13 @@  typedef struct DirtyBitmapMigState {
     BlockDriverState *prev_bs;
     BdrvDirtyBitmap *prev_bitmap;
 } DirtyBitmapMigState;
+static DirtyBitmapMigState dirty_bitmap_mig_state;
+
+typedef struct DirtyBitmapLoadBitmapState {
+    BlockDriverState *bs;
+    BdrvDirtyBitmap *bitmap;
+    bool migrated;
+} DirtyBitmapLoadBitmapState;
 
 typedef struct DirtyBitmapLoadState {
     uint32_t flags;
@@ -132,21 +139,15 @@  typedef struct DirtyBitmapLoadState {
     char bitmap_name[256];
     BlockDriverState *bs;
     BdrvDirtyBitmap *bitmap;
-} DirtyBitmapLoadState;
 
-static DirtyBitmapMigState dirty_bitmap_mig_state;
-
-typedef struct DirtyBitmapLoadBitmapState {
-    BlockDriverState *bs;
-    BdrvDirtyBitmap *bitmap;
-    bool migrated;
-} DirtyBitmapLoadBitmapState;
-static GSList *enabled_bitmaps;
-QemuMutex finish_lock;
+    GSList *enabled_bitmaps;
+    QemuMutex finish_lock;
+} DirtyBitmapLoadState;
+static DirtyBitmapLoadState dbm_load_state;
 
 void init_dirty_bitmap_incoming_migration(void)
 {
-    qemu_mutex_init(&finish_lock);
+    qemu_mutex_init(&dbm_load_state.finish_lock);
 }
 
 static uint32_t qemu_get_bitmap_flags(QEMUFile *f)
@@ -439,8 +440,9 @@  static void dirty_bitmap_save_pending(QEMUFile *f, void *opaque,
 }
 
 /* First occurrence of this bitmap. It should be created if doesn't exist */
-static int dirty_bitmap_load_start(QEMUFile *f, DirtyBitmapLoadState *s)
+static int dirty_bitmap_load_start(QEMUFile *f)
 {
+    DirtyBitmapLoadState *s = &dbm_load_state;
     Error *local_err = NULL;
     uint32_t granularity = qemu_get_be32(f);
     uint8_t flags = qemu_get_byte(f);
@@ -482,7 +484,8 @@  static int dirty_bitmap_load_start(QEMUFile *f, DirtyBitmapLoadState *s)
         b->bs = s->bs;
         b->bitmap = s->bitmap;
         b->migrated = false;
-        enabled_bitmaps = g_slist_prepend(enabled_bitmaps, b);
+        dbm_load_state.enabled_bitmaps =
+            g_slist_prepend(dbm_load_state.enabled_bitmaps, b);
     }
 
     return 0;
@@ -492,9 +495,11 @@  void dirty_bitmap_mig_before_vm_start(void)
 {
     GSList *item;
 
-    qemu_mutex_lock(&finish_lock);
+    qemu_mutex_lock(&dbm_load_state.finish_lock);
 
-    for (item = enabled_bitmaps; item; item = g_slist_next(item)) {
+    for (item = dbm_load_state.enabled_bitmaps; item;
+         item = g_slist_next(item))
+    {
         DirtyBitmapLoadBitmapState *b = item->data;
 
         if (b->migrated) {
@@ -506,21 +511,24 @@  void dirty_bitmap_mig_before_vm_start(void)
         g_free(b);
     }
 
-    g_slist_free(enabled_bitmaps);
-    enabled_bitmaps = NULL;
+    g_slist_free(dbm_load_state.enabled_bitmaps);
+    dbm_load_state.enabled_bitmaps = NULL;
 
-    qemu_mutex_unlock(&finish_lock);
+    qemu_mutex_unlock(&dbm_load_state.finish_lock);
 }
 
-static void dirty_bitmap_load_complete(QEMUFile *f, DirtyBitmapLoadState *s)
+static void dirty_bitmap_load_complete(QEMUFile *f)
 {
+    DirtyBitmapLoadState *s = &dbm_load_state;
     GSList *item;
     trace_dirty_bitmap_load_complete();
     bdrv_dirty_bitmap_deserialize_finish(s->bitmap);
 
-    qemu_mutex_lock(&finish_lock);
+    qemu_mutex_lock(&dbm_load_state.finish_lock);
 
-    for (item = enabled_bitmaps; item; item = g_slist_next(item)) {
+    for (item = dbm_load_state.enabled_bitmaps; item;
+         item = g_slist_next(item))
+    {
         DirtyBitmapLoadBitmapState *b = item->data;
 
         if (b->bitmap == s->bitmap) {
@@ -531,7 +539,7 @@  static void dirty_bitmap_load_complete(QEMUFile *f, DirtyBitmapLoadState *s)
 
     if (bdrv_dirty_bitmap_has_successor(s->bitmap)) {
         bdrv_dirty_bitmap_lock(s->bitmap);
-        if (enabled_bitmaps == NULL) {
+        if (dbm_load_state.enabled_bitmaps == NULL) {
             /* in postcopy */
             bdrv_reclaim_dirty_bitmap_locked(s->bitmap, &error_abort);
             bdrv_enable_dirty_bitmap_locked(s->bitmap);
@@ -550,11 +558,12 @@  static void dirty_bitmap_load_complete(QEMUFile *f, DirtyBitmapLoadState *s)
         bdrv_dirty_bitmap_unlock(s->bitmap);
     }
 
-    qemu_mutex_unlock(&finish_lock);
+    qemu_mutex_unlock(&dbm_load_state.finish_lock);
 }
 
-static int dirty_bitmap_load_bits(QEMUFile *f, DirtyBitmapLoadState *s)
+static int dirty_bitmap_load_bits(QEMUFile *f)
 {
+    DirtyBitmapLoadState *s = &dbm_load_state;
     uint64_t first_byte = qemu_get_be64(f) << BDRV_SECTOR_BITS;
     uint64_t nr_bytes = (uint64_t)qemu_get_be32(f) << BDRV_SECTOR_BITS;
     trace_dirty_bitmap_load_bits_enter(first_byte >> BDRV_SECTOR_BITS,
@@ -598,8 +607,9 @@  static int dirty_bitmap_load_bits(QEMUFile *f, DirtyBitmapLoadState *s)
     return 0;
 }
 
-static int dirty_bitmap_load_header(QEMUFile *f, DirtyBitmapLoadState *s)
+static int dirty_bitmap_load_header(QEMUFile *f)
 {
+    DirtyBitmapLoadState *s = &dbm_load_state;
     Error *local_err = NULL;
     bool nothing;
     s->flags = qemu_get_bitmap_flags(f);
@@ -647,7 +657,6 @@  static int dirty_bitmap_load_header(QEMUFile *f, DirtyBitmapLoadState *s)
 
 static int dirty_bitmap_load(QEMUFile *f, void *opaque, int version_id)
 {
-    static DirtyBitmapLoadState s;
     int ret = 0;
 
     trace_dirty_bitmap_load_enter();
@@ -657,17 +666,17 @@  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);
         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 (dbm_load_state.flags & DIRTY_BITMAP_MIG_FLAG_START) {
+            ret = dirty_bitmap_load_start(f);
+        } else if (dbm_load_state.flags & DIRTY_BITMAP_MIG_FLAG_COMPLETE) {
+            dirty_bitmap_load_complete(f);
+        } else if (dbm_load_state.flags & DIRTY_BITMAP_MIG_FLAG_BITS) {
+            ret = dirty_bitmap_load_bits(f);
         }
 
         if (!ret) {
@@ -677,7 +686,7 @@  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 (!(dbm_load_state.flags & DIRTY_BITMAP_MIG_FLAG_EOS));
 
     trace_dirty_bitmap_load_success();
     return 0;