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From: Eric Blake <eblake@redhat.com>
To: qemu-devel@nongnu.org
Cc: kwolf@redhat.com, jsnow@redhat.com, famz@redhat.com,
	vsementsov@virtuozzo.com, qemu-block@nongnu.org,
	Max Reitz <mreitz@redhat.com>
Subject: [Qemu-devel] [PATCH v10 07/20] dirty-bitmap: Track bitmap size by bytes
Date: Mon, 25 Sep 2017 09:55:13 -0500	[thread overview]
Message-ID: <20170925145526.32690-8-eblake@redhat.com> (raw)
In-Reply-To: <20170925145526.32690-1-eblake@redhat.com>

We are still using an internal hbitmap that tracks a size in sectors,
with the granularity scaled down accordingly, because it lets us
use a shortcut for our iterators which are currently sector-based.
But there's no reason we can't track the dirty bitmap size in bytes,
since it is (mostly) an internal-only variable (remember, the size
is how many bytes are covered by the bitmap, not how many bytes the
bitmap occupies).  A later cleanup will convert dirty bitmap
internals to be entirely byte-based, eliminating the intermediate
sector rounding added here; and technically, since bdrv_getlength()
already rounds up to sectors, our use of DIV_ROUND_UP is more for
theoretical completeness than for any actual rounding.

Use is_power_of_2() while at it, instead of open-coding that.

Signed-off-by: Eric Blake <eblake@redhat.com>
Reviewed-by: John Snow <jsnow@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Fam Zheng <famz@redhat.com>

---
v8: rebase to earlier truncate changes, R-b kept
v7: split external from internal [Kevin], drop R-b
v6: no change
v5: fix bdrv_dirty_bitmap_truncate [John], drop R-b
v4: retitle from "Track size in bytes", rebase to persistent bitmaps,
round up when converting bytes to sectors
v3: no change
v2: tweak commit message, no code change
---
 block/dirty-bitmap.c | 26 ++++++++++++++------------
 1 file changed, 14 insertions(+), 12 deletions(-)

diff --git a/block/dirty-bitmap.c b/block/dirty-bitmap.c
index 755555af32..6d32554b4e 100644
--- a/block/dirty-bitmap.c
+++ b/block/dirty-bitmap.c
@@ -42,7 +42,7 @@ struct BdrvDirtyBitmap {
     HBitmap *meta;              /* Meta dirty bitmap */
     BdrvDirtyBitmap *successor; /* Anonymous child; implies frozen status */
     char *name;                 /* Optional non-empty unique ID */
-    int64_t size;               /* Size of the bitmap (Number of sectors) */
+    int64_t size;               /* Size of the bitmap, in bytes */
     bool disabled;              /* Bitmap is disabled. It ignores all writes to
                                    the device */
     int active_iterators;       /* How many iterators are active */
@@ -115,17 +115,14 @@ BdrvDirtyBitmap *bdrv_create_dirty_bitmap(BlockDriverState *bs,
 {
     int64_t bitmap_size;
     BdrvDirtyBitmap *bitmap;
-    uint32_t sector_granularity;

-    assert((granularity & (granularity - 1)) == 0);
+    assert(is_power_of_2(granularity) && granularity >= BDRV_SECTOR_SIZE);

     if (name && bdrv_find_dirty_bitmap(bs, name)) {
         error_setg(errp, "Bitmap already exists: %s", name);
         return NULL;
     }
-    sector_granularity = granularity >> BDRV_SECTOR_BITS;
-    assert(sector_granularity);
-    bitmap_size = bdrv_nb_sectors(bs);
+    bitmap_size = bdrv_getlength(bs);
     if (bitmap_size < 0) {
         error_setg_errno(errp, -bitmap_size, "could not get length of device");
         errno = -bitmap_size;
@@ -133,7 +130,12 @@ BdrvDirtyBitmap *bdrv_create_dirty_bitmap(BlockDriverState *bs,
     }
     bitmap = g_new0(BdrvDirtyBitmap, 1);
     bitmap->mutex = &bs->dirty_bitmap_mutex;
-    bitmap->bitmap = hbitmap_alloc(bitmap_size, ctz32(sector_granularity));
+    /*
+     * TODO - let hbitmap track full granularity. For now, it is tracking
+     * only sector granularity, as a shortcut for our iterators.
+     */
+    bitmap->bitmap = hbitmap_alloc(DIV_ROUND_UP(bitmap_size, BDRV_SECTOR_SIZE),
+                                   ctz32(granularity) - BDRV_SECTOR_BITS);
     bitmap->size = bitmap_size;
     bitmap->name = g_strdup(name);
     bitmap->disabled = false;
@@ -175,7 +177,7 @@ void bdrv_release_meta_dirty_bitmap(BdrvDirtyBitmap *bitmap)

 int64_t bdrv_dirty_bitmap_size(const BdrvDirtyBitmap *bitmap)
 {
-    return bitmap->size * BDRV_SECTOR_SIZE;
+    return bitmap->size;
 }

 const char *bdrv_dirty_bitmap_name(const BdrvDirtyBitmap *bitmap)
@@ -305,14 +307,13 @@ BdrvDirtyBitmap *bdrv_reclaim_dirty_bitmap(BlockDriverState *bs,
 void bdrv_dirty_bitmap_truncate(BlockDriverState *bs, int64_t bytes)
 {
     BdrvDirtyBitmap *bitmap;
-    int64_t size = DIV_ROUND_UP(bytes, BDRV_SECTOR_SIZE);

     bdrv_dirty_bitmaps_lock(bs);
     QLIST_FOREACH(bitmap, &bs->dirty_bitmaps, list) {
         assert(!bdrv_dirty_bitmap_frozen(bitmap));
         assert(!bitmap->active_iterators);
-        hbitmap_truncate(bitmap->bitmap, size);
-        bitmap->size = size;
+        hbitmap_truncate(bitmap->bitmap, DIV_ROUND_UP(bytes, BDRV_SECTOR_SIZE));
+        bitmap->size = bytes;
     }
     bdrv_dirty_bitmaps_unlock(bs);
 }
@@ -549,7 +550,8 @@ void bdrv_clear_dirty_bitmap(BdrvDirtyBitmap *bitmap, HBitmap **out)
         hbitmap_reset_all(bitmap->bitmap);
     } else {
         HBitmap *backup = bitmap->bitmap;
-        bitmap->bitmap = hbitmap_alloc(bitmap->size,
+        bitmap->bitmap = hbitmap_alloc(DIV_ROUND_UP(bitmap->size,
+                                                    BDRV_SECTOR_SIZE),
                                        hbitmap_granularity(backup));
         *out = backup;
     }
-- 
2.13.5

  parent reply	other threads:[~2017-09-25 14:56 UTC|newest]

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-09-25 14:55 [Qemu-devel] [PATCH v10 00/20] make dirty-bitmap byte-based Eric Blake
2017-09-25 14:55 ` [Qemu-devel] [PATCH v10 01/20] block: Make bdrv_img_create() size selection easier to read Eric Blake
2017-09-25 14:55 ` [Qemu-devel] [PATCH v10 02/20] hbitmap: Rename serialization_granularity to serialization_align Eric Blake
2017-09-25 14:55 ` [Qemu-devel] [PATCH v10 03/20] qcow2: Ensure bitmap serialization is aligned Eric Blake
2017-09-25 14:55 ` [Qemu-devel] [PATCH v10 04/20] dirty-bitmap: Drop unused functions Eric Blake
2017-09-25 14:55 ` [Qemu-devel] [PATCH v10 05/20] dirty-bitmap: Avoid size query failure during truncate Eric Blake
2017-09-25 15:23   ` Vladimir Sementsov-Ogievskiy
2017-09-25 15:46     ` Eric Blake
2017-10-02 16:06       ` Kevin Wolf
2017-09-25 20:54   ` John Snow
2017-09-26  1:25   ` Fam Zheng
2017-09-25 14:55 ` [Qemu-devel] [PATCH v10 06/20] dirty-bitmap: Change bdrv_dirty_bitmap_size() to report bytes Eric Blake
2017-09-25 14:55 ` Eric Blake [this message]
2017-09-25 14:55 ` [Qemu-devel] [PATCH v10 08/20] dirty-bitmap: Change bdrv_dirty_bitmap_*serialize*() to take bytes Eric Blake
2017-09-25 14:55 ` [Qemu-devel] [PATCH v10 09/20] qcow2: Switch sectors_covered_by_bitmap_cluster() to byte-based Eric Blake
2017-09-25 14:55 ` [Qemu-devel] [PATCH v10 10/20] dirty-bitmap: Set iterator start by offset, not sector Eric Blake
2017-09-25 14:55 ` [Qemu-devel] [PATCH v10 11/20] dirty-bitmap: Change bdrv_dirty_iter_next() to report byte offset Eric Blake
2017-09-25 14:55 ` [Qemu-devel] [PATCH v10 12/20] dirty-bitmap: Change bdrv_get_dirty_count() to report bytes Eric Blake
2017-09-25 14:55 ` [Qemu-devel] [PATCH v10 13/20] dirty-bitmap: Change bdrv_get_dirty_locked() to take bytes Eric Blake
2017-09-25 14:55 ` [Qemu-devel] [PATCH v10 14/20] dirty-bitmap: Change bdrv_[re]set_dirty_bitmap() to use bytes Eric Blake
2017-09-25 14:55 ` [Qemu-devel] [PATCH v10 15/20] mirror: Switch mirror_dirty_init() to byte-based iteration Eric Blake
2017-09-25 14:55 ` [Qemu-devel] [PATCH v10 16/20] qcow2: Switch qcow2_measure() " Eric Blake
2017-09-25 14:55 ` [Qemu-devel] [PATCH v10 17/20] qcow2: Switch load_bitmap_data() " Eric Blake
2017-09-25 14:55 ` [Qemu-devel] [PATCH v10 18/20] qcow2: Switch store_bitmap_data() " Eric Blake
2017-09-25 15:22   ` Vladimir Sementsov-Ogievskiy
2017-09-25 21:00   ` John Snow
2017-09-26  1:30   ` Fam Zheng
2017-09-25 14:55 ` [Qemu-devel] [PATCH v10 19/20] dirty-bitmap: Switch bdrv_set_dirty() to bytes Eric Blake
2017-09-25 14:55 ` [Qemu-devel] [PATCH v10 20/20] dirty-bitmap: Convert internal hbitmap size/granularity Eric Blake
2017-09-25 22:18 ` [Qemu-devel] [PATCH v10 00/20] make dirty-bitmap byte-based John Snow
2017-10-02 16:22 ` Kevin Wolf

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