On 01/16/2015 11:28 AM, Max Reitz wrote:
On 2015-01-12 at 11:30, John Snow wrote:
From: Fam Zheng <f...@redhat.com>
This allows to put the dirty bitmap into a disabled state where no more
writes will be tracked.
It will be used before backup or writing to persistent file.
Signed-off-by: Fam Zheng <f...@redhat.com>
Signed-off-by: John Snow <js...@redhat.com>
---
block.c | 24 +++++++++++++++++++++++-
blockdev.c | 40 ++++++++++++++++++++++++++++++++++++++++
include/block/block.h | 3 +++
qapi/block-core.json | 28 ++++++++++++++++++++++++++++
qmp-commands.hx | 10 ++++++++++
5 files changed, 104 insertions(+), 1 deletion(-)
diff --git a/block.c b/block.c
index 7bf7079..bd4b449 100644
--- a/block.c
+++ b/block.c
@@ -56,6 +56,7 @@ struct BdrvDirtyBitmap {
int64_t size;
int64_t granularity;
char *name;
+ bool enabled;
QLIST_ENTRY(BdrvDirtyBitmap) list;
};
@@ -5373,10 +5374,16 @@ BdrvDirtyBitmap
*bdrv_create_dirty_bitmap(BlockDriverState *bs,
bitmap->granularity = granularity;
bitmap->bitmap = hbitmap_alloc(bitmap->size,
ffs(sector_granularity) - 1);
bitmap->name = g_strdup(name);
+ bitmap->enabled = true;
QLIST_INSERT_HEAD(&bs->dirty_bitmaps, bitmap, list);
return bitmap;
}
+bool bdrv_dirty_bitmap_enabled(BdrvDirtyBitmap *bitmap)
+{
+ return bitmap->enabled;
+}
+
void bdrv_release_dirty_bitmap(BlockDriverState *bs, BdrvDirtyBitmap
*bitmap)
{
BdrvDirtyBitmap *bm, *next;
@@ -5391,6 +5398,16 @@ void bdrv_release_dirty_bitmap(BlockDriverState
*bs, BdrvDirtyBitmap *bitmap)
}
}
+void bdrv_disable_dirty_bitmap(BdrvDirtyBitmap *bitmap)
+{
+ bitmap->enabled = false;
+}
+
+void bdrv_enable_dirty_bitmap(BdrvDirtyBitmap *bitmap)
+{
+ bitmap->enabled = true;
+}
+
BlockDirtyInfoList *bdrv_query_dirty_bitmaps(BlockDriverState *bs)
{
BdrvDirtyBitmap *bm;
@@ -5458,7 +5475,9 @@ void bdrv_dirty_iter_init(BlockDriverState *bs,
void bdrv_set_dirty_bitmap(BlockDriverState *bs, BdrvDirtyBitmap
*bitmap,
int64_t cur_sector, int nr_sectors)
{
- hbitmap_set(bitmap->bitmap, cur_sector, nr_sectors);
+ if (bdrv_dirty_bitmap_enabled(bitmap)) {
+ hbitmap_set(bitmap->bitmap, cur_sector, nr_sectors);
+ }
Why are you checking whether the bitmap is enabled here in
bdrv_set_dirty_bitmap(), but neither in bdrv_reset_dirty_bitmap() nor
bdrv_clear_dirty_bitmap()?
It seems consistent with the commit message which only states that
disabled state means that no more writes (i.e. bdrv_set_dirty_bitmap())
will be tracked, but it still seems strange to me.
}
void bdrv_reset_dirty_bitmap(BlockDriverState *bs, BdrvDirtyBitmap
*bitmap,
@@ -5481,6 +5500,9 @@ static void bdrv_set_dirty(BlockDriverState *bs,
int64_t cur_sector,
{
BdrvDirtyBitmap *bitmap;
QLIST_FOREACH(bitmap, &bs->dirty_bitmaps, list) {
+ if (!bdrv_dirty_bitmap_enabled(bitmap)) {
+ continue;
+ }
Same question as above, only this time it's about bdrv_reset_dirty().
In case the answer to the question is "that's intentional":
Reviewed-by: Max Reitz <mre...@redhat.com>
Just because it's intentional doesn't make it a good idea.
Fam is currently suggesting we might just scrap the "enable/disable" and
"frozen/normal" modes altogether in favor of a single unified status,
but the original way he proposed enabled/disabled is that it simply, and
exclusively enabled/disabled new writes to the bitmap -- it never was
intended to block clears/resets.
So the bitmap is still able to be consumed while disabled, for instance.
How useful is this? Perhaps not very useful. Probably more confusing
than useful.
I will *probably* try to unify these parameters as Fam suggested, but I
am really eager to hear from Markus on the QMP interface side before I
bother sending out another minor iteration.
I'll skip the R-b for now, since Fam had some ideas on how to make it nicer.
Thanks!
--js
