[Qemu-devel] [PATCH v8 00/10] Dirty bitmap changes for migration/persistence work

[Qemu-devel] [PATCH v8 00/10] Dirty bitmap changes for migration/persistence work

[John Snow]

Key:
[----] : patches are identical
[####] : number of functional differences between upstream/downstream patch
[down] : patch is downstream-only
The flags [FC] indicate (F)unctional and (C)ontextual differences, respectively

001/10:[----] [-C] 'block: Hide HBitmap in block dirty bitmap interface'
002/10:[----] [--] 'HBitmap: Introduce "meta" bitmap to track bit changes'
003/10:[----] [--] 'tests: Add test code for meta bitmap'
004/10:[0004] [FC] 'block: Support meta dirty bitmap'
005/10:[----] [--] 'block: Add two dirty bitmap getters'
006/10:[----] [--] 'block: Assert that bdrv_release_dirty_bitmap succeeded'
007/10:[----] [--] 'hbitmap: serialization'
008/10:[----] [-C] 'block: BdrvDirtyBitmap serialization interface'
009/10:[----] [--] 'tests: Add test code for hbitmap serialization'
010/10:[----] [--] 'block: More operations for meta dirty bitmap'

===
v8: Hello, is it v8 you're looking for?
===

01: Rebase conflict over int64_t header for bdrv_reset_dirty_bitmap.
04: Revised sector math to make literally any sense.
08: Rebase conflict over int64_t header for bdrv_reset_dirty_bitmap.

===
v7:
===

02: Fix rebase mishap.
04: Slight loop adjustment.
09: Fix constant on 32bit machines.

===
v6: Rebase. Stole series from Fam.
===

02: Added documentation changes as suggested by Max.

===
v5: Rebase: first 5 patches from last revision are already merged.
===

Addressed Max's comments:

01: - "block.c" -> "block/dirty-bitmap.c" in commit message.
    - "an BdrvDirtyBitmapIter" -> "an BdrvDirtyBitmapIter" in code comment.
    - hbitmap_next => next_dirty as variable name.
    - bdrv_dirty_iter_free()/bdrv_dirty_iter_new() pairs =>
      bdrv_set_dirty_iter.

02: Move the assert fix into 01.

04: Truncate the meta bitmap (done by hbitmap_truncate).

06: Add Max's r-b.

07: I left the memcpy vs cpu_to_le32/64w as is to pick up Max's r-b. That
    could be improved on top if wanted.

10: Add Max's r-b.

________________________________________________________________________________

For convenience, this branch is available at:
https://github.com/jnsnow/qemu.git branch meta-bitmap
https://github.com/jnsnow/qemu/tree/meta-bitmap

This version is tagged meta-bitmap-v8:
https://github.com/jnsnow/qemu/releases/tag/meta-bitmap-v8

Fam Zheng (8):
  block: Hide HBitmap in block dirty bitmap interface
  HBitmap: Introduce "meta" bitmap to track bit changes
  tests: Add test code for meta bitmap
  block: Support meta dirty bitmap
  block: Add two dirty bitmap getters
  block: Assert that bdrv_release_dirty_bitmap succeeded
  tests: Add test code for hbitmap serialization
  block: More operations for meta dirty bitmap

Vladimir Sementsov-Ogievskiy (2):
  hbitmap: serialization
  block: BdrvDirtyBitmap serialization interface

 block/backup.c               |  14 ++-
 block/dirty-bitmap.c         | 160 ++++++++++++++++++++++++++-
 block/mirror.c               |  24 ++--
 include/block/dirty-bitmap.h |  35 +++++-
 include/qemu/hbitmap.h       | 100 +++++++++++++++++
 include/qemu/typedefs.h      |   1 +
 tests/test-hbitmap.c         | 255 +++++++++++++++++++++++++++++++++++++++++++
 util/hbitmap.c               | 206 +++++++++++++++++++++++++++++++---
 8 files changed, 755 insertions(+), 40 deletions(-)

-- 
2.7.4

[Qemu-devel] [PATCH v8 01/10] block: Hide HBitmap in block dirty bitmap interface

[John Snow]

From: Fam Zheng <famz@redhat.com>

HBitmap is an implementation detail of block dirty bitmap that should be hidden
from users. Introduce a BdrvDirtyBitmapIter to encapsulate the underlying
HBitmapIter.

A small difference in the interface is, before, an HBitmapIter is initialized
in place, now the new BdrvDirtyBitmapIter must be dynamically allocated because
the structure definition is in block/dirty-bitmap.c.

Two current users are converted too.

Signed-off-by: Fam Zheng <famz@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: John Snow <jsnow@redhat.com>
---
 block/backup.c               | 14 ++++++++------
 block/dirty-bitmap.c         | 39 +++++++++++++++++++++++++++++++++------
 block/mirror.c               | 24 +++++++++++++-----------
 include/block/dirty-bitmap.h |  7 +++++--
 include/qemu/typedefs.h      |  1 +
 5 files changed, 60 insertions(+), 25 deletions(-)

diff --git a/block/backup.c b/block/backup.c
index 2c05323..fc0fccf 100644
--- a/block/backup.c
+++ b/block/backup.c
@@ -325,14 +325,14 @@ static int coroutine_fn backup_run_incremental(BackupBlockJob *job)
     int64_t end;
     int64_t last_cluster = -1;
     int64_t sectors_per_cluster = cluster_size_sectors(job);
-    HBitmapIter hbi;
+    BdrvDirtyBitmapIter *dbi;
 
     granularity = bdrv_dirty_bitmap_granularity(job->sync_bitmap);
     clusters_per_iter = MAX((granularity / job->cluster_size), 1);
-    bdrv_dirty_iter_init(job->sync_bitmap, &hbi);
+    dbi = bdrv_dirty_iter_new(job->sync_bitmap, 0);
 
     /* Find the next dirty sector(s) */
-    while ((sector = hbitmap_iter_next(&hbi)) != -1) {
+    while ((sector = bdrv_dirty_iter_next(dbi)) != -1) {
         cluster = sector / sectors_per_cluster;
 
         /* Fake progress updates for any clusters we skipped */
@@ -344,7 +344,7 @@ static int coroutine_fn backup_run_incremental(BackupBlockJob *job)
         for (end = cluster + clusters_per_iter; cluster < end; cluster++) {
             do {
                 if (yield_and_check(job)) {
-                    return ret;
+                    goto out;
                 }
                 ret = backup_do_cow(job, cluster * sectors_per_cluster,
                                     sectors_per_cluster, &error_is_read,
@@ -352,7 +352,7 @@ static int coroutine_fn backup_run_incremental(BackupBlockJob *job)
                 if ((ret < 0) &&
                     backup_error_action(job, error_is_read, -ret) ==
                     BLOCK_ERROR_ACTION_REPORT) {
-                    return ret;
+                    goto out;
                 }
             } while (ret < 0);
         }
@@ -360,7 +360,7 @@ static int coroutine_fn backup_run_incremental(BackupBlockJob *job)
         /* If the bitmap granularity is smaller than the backup granularity,
          * we need to advance the iterator pointer to the next cluster. */
         if (granularity < job->cluster_size) {
-            bdrv_set_dirty_iter(&hbi, cluster * sectors_per_cluster);
+            bdrv_set_dirty_iter(dbi, cluster * sectors_per_cluster);
         }
 
         last_cluster = cluster - 1;
@@ -372,6 +372,8 @@ static int coroutine_fn backup_run_incremental(BackupBlockJob *job)
         job->common.offset += ((end - last_cluster - 1) * job->cluster_size);
     }
 
+out:
+    bdrv_dirty_iter_free(dbi);
     return ret;
 }
 
diff --git a/block/dirty-bitmap.c b/block/dirty-bitmap.c
index f2bfdcf..c572dfa 100644
--- a/block/dirty-bitmap.c
+++ b/block/dirty-bitmap.c
@@ -42,9 +42,15 @@ struct BdrvDirtyBitmap {
     char *name;                 /* Optional non-empty unique ID */
     int64_t size;               /* Size of the bitmap (Number of sectors) */
     bool disabled;              /* Bitmap is read-only */
+    int active_iterators;       /* How many iterators are active */
     QLIST_ENTRY(BdrvDirtyBitmap) list;
 };
 
+struct BdrvDirtyBitmapIter {
+    HBitmapIter hbi;
+    BdrvDirtyBitmap *bitmap;
+};
+
 BdrvDirtyBitmap *bdrv_find_dirty_bitmap(BlockDriverState *bs, const char *name)
 {
     BdrvDirtyBitmap *bm;
@@ -212,6 +218,7 @@ void bdrv_dirty_bitmap_truncate(BlockDriverState *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;
     }
@@ -224,6 +231,7 @@ static void bdrv_do_release_matching_dirty_bitmap(BlockDriverState *bs,
     BdrvDirtyBitmap *bm, *next;
     QLIST_FOREACH_SAFE(bm, &bs->dirty_bitmaps, list, next) {
         if ((!bitmap || bm == bitmap) && (!only_named || bm->name)) {
+            assert(!bm->active_iterators);
             assert(!bdrv_dirty_bitmap_frozen(bm));
             QLIST_REMOVE(bm, list);
             hbitmap_free(bm->bitmap);
@@ -320,9 +328,29 @@ uint32_t bdrv_dirty_bitmap_granularity(BdrvDirtyBitmap *bitmap)
     return BDRV_SECTOR_SIZE << hbitmap_granularity(bitmap->bitmap);
 }
 
-void bdrv_dirty_iter_init(BdrvDirtyBitmap *bitmap, HBitmapIter *hbi)
+BdrvDirtyBitmapIter *bdrv_dirty_iter_new(BdrvDirtyBitmap *bitmap,
+                                         uint64_t first_sector)
 {
-    hbitmap_iter_init(hbi, bitmap->bitmap, 0);
+    BdrvDirtyBitmapIter *iter = g_new(BdrvDirtyBitmapIter, 1);
+    hbitmap_iter_init(&iter->hbi, bitmap->bitmap, first_sector);
+    iter->bitmap = bitmap;
+    bitmap->active_iterators++;
+    return iter;
+}
+
+void bdrv_dirty_iter_free(BdrvDirtyBitmapIter *iter)
+{
+    if (!iter) {
+        return;
+    }
+    assert(iter->bitmap->active_iterators > 0);
+    iter->bitmap->active_iterators--;
+    g_free(iter);
+}
+
+int64_t bdrv_dirty_iter_next(BdrvDirtyBitmapIter *iter)
+{
+    return hbitmap_iter_next(&iter->hbi);
 }
 
 void bdrv_set_dirty_bitmap(BdrvDirtyBitmap *bitmap,
@@ -373,12 +401,11 @@ void bdrv_set_dirty(BlockDriverState *bs, int64_t cur_sector,
 }
 
 /**
- * Advance an HBitmapIter to an arbitrary offset.
+ * Advance a BdrvDirtyBitmapIter to an arbitrary offset.
  */
-void bdrv_set_dirty_iter(HBitmapIter *hbi, int64_t offset)
+void bdrv_set_dirty_iter(BdrvDirtyBitmapIter *iter, int64_t sector_num)
 {
-    assert(hbi->hb);
-    hbitmap_iter_init(hbi, hbi->hb, offset);
+    hbitmap_iter_init(&iter->hbi, iter->hbi.hb, sector_num);
 }
 
 int64_t bdrv_get_dirty_count(BdrvDirtyBitmap *bitmap)
diff --git a/block/mirror.c b/block/mirror.c
index d6034f5..8df5aa2 100644
--- a/block/mirror.c
+++ b/block/mirror.c
@@ -55,7 +55,7 @@ typedef struct MirrorBlockJob {
     int64_t bdev_length;
     unsigned long *cow_bitmap;
     BdrvDirtyBitmap *dirty_bitmap;
-    HBitmapIter hbi;
+    BdrvDirtyBitmapIter *dbi;
     uint8_t *buf;
     QSIMPLEQ_HEAD(, MirrorBuffer) buf_free;
     int buf_free_count;
@@ -330,10 +330,10 @@ static uint64_t coroutine_fn mirror_iteration(MirrorBlockJob *s)
     int max_io_sectors = MAX((s->buf_size >> BDRV_SECTOR_BITS) / MAX_IN_FLIGHT,
                              MAX_IO_SECTORS);
 
-    sector_num = hbitmap_iter_next(&s->hbi);
+    sector_num = bdrv_dirty_iter_next(s->dbi);
     if (sector_num < 0) {
-        bdrv_dirty_iter_init(s->dirty_bitmap, &s->hbi);
-        sector_num = hbitmap_iter_next(&s->hbi);
+        bdrv_set_dirty_iter(s->dbi, 0);
+        sector_num = bdrv_dirty_iter_next(s->dbi);
         trace_mirror_restart_iter(s, bdrv_get_dirty_count(s->dirty_bitmap));
         assert(sector_num >= 0);
     }
@@ -349,7 +349,7 @@ static uint64_t coroutine_fn mirror_iteration(MirrorBlockJob *s)
     /* Find the number of consective dirty chunks following the first dirty
      * one, and wait for in flight requests in them. */
     while (nb_chunks * sectors_per_chunk < (s->buf_size >> BDRV_SECTOR_BITS)) {
-        int64_t hbitmap_next;
+        int64_t next_dirty;
         int64_t next_sector = sector_num + nb_chunks * sectors_per_chunk;
         int64_t next_chunk = next_sector / sectors_per_chunk;
         if (next_sector >= end ||
@@ -360,13 +360,13 @@ static uint64_t coroutine_fn mirror_iteration(MirrorBlockJob *s)
             break;
         }
 
-        hbitmap_next = hbitmap_iter_next(&s->hbi);
-        if (hbitmap_next > next_sector || hbitmap_next < 0) {
+        next_dirty = bdrv_dirty_iter_next(s->dbi);
+        if (next_dirty > next_sector || next_dirty < 0) {
             /* The bitmap iterator's cache is stale, refresh it */
-            bdrv_set_dirty_iter(&s->hbi, next_sector);
-            hbitmap_next = hbitmap_iter_next(&s->hbi);
+            bdrv_set_dirty_iter(s->dbi, next_sector);
+            next_dirty = bdrv_dirty_iter_next(s->dbi);
         }
-        assert(hbitmap_next == next_sector);
+        assert(next_dirty == next_sector);
         nb_chunks++;
     }
 
@@ -675,7 +675,8 @@ static void coroutine_fn mirror_run(void *opaque)
         }
     }
 
-    bdrv_dirty_iter_init(s->dirty_bitmap, &s->hbi);
+    assert(!s->dbi);
+    s->dbi = bdrv_dirty_iter_new(s->dirty_bitmap, 0);
     for (;;) {
         uint64_t delay_ns = 0;
         int64_t cnt, delta;
@@ -789,6 +790,7 @@ immediate_exit:
     qemu_vfree(s->buf);
     g_free(s->cow_bitmap);
     g_free(s->in_flight_bitmap);
+    bdrv_dirty_iter_free(s->dbi);
     bdrv_release_dirty_bitmap(bs, s->dirty_bitmap);
 
     data = g_malloc(sizeof(*data));
diff --git a/include/block/dirty-bitmap.h b/include/block/dirty-bitmap.h
index ee3388f..0ef927d 100644
--- a/include/block/dirty-bitmap.h
+++ b/include/block/dirty-bitmap.h
@@ -36,8 +36,11 @@ void bdrv_set_dirty_bitmap(BdrvDirtyBitmap *bitmap,
                            int64_t cur_sector, int64_t nr_sectors);
 void bdrv_reset_dirty_bitmap(BdrvDirtyBitmap *bitmap,
                              int64_t cur_sector, int64_t nr_sectors);
-void bdrv_dirty_iter_init(BdrvDirtyBitmap *bitmap, struct HBitmapIter *hbi);
-void bdrv_set_dirty_iter(struct HBitmapIter *hbi, int64_t offset);
+BdrvDirtyBitmapIter *bdrv_dirty_iter_new(BdrvDirtyBitmap *bitmap,
+                                         uint64_t first_sector);
+void bdrv_dirty_iter_free(BdrvDirtyBitmapIter *iter);
+int64_t bdrv_dirty_iter_next(BdrvDirtyBitmapIter *iter);
+void bdrv_set_dirty_iter(BdrvDirtyBitmapIter *hbi, int64_t sector_num);
 int64_t bdrv_get_dirty_count(BdrvDirtyBitmap *bitmap);
 void bdrv_dirty_bitmap_truncate(BlockDriverState *bs);
 
diff --git a/include/qemu/typedefs.h b/include/qemu/typedefs.h
index b113fcf..1b8c30a 100644
--- a/include/qemu/typedefs.h
+++ b/include/qemu/typedefs.h
@@ -11,6 +11,7 @@ typedef struct AioContext AioContext;
 typedef struct AllwinnerAHCIState AllwinnerAHCIState;
 typedef struct AudioState AudioState;
 typedef struct BdrvDirtyBitmap BdrvDirtyBitmap;
+typedef struct BdrvDirtyBitmapIter BdrvDirtyBitmapIter;
 typedef struct BlockBackend BlockBackend;
 typedef struct BlockBackendRootState BlockBackendRootState;
 typedef struct BlockDriverState BlockDriverState;
-- 
2.7.4

[Qemu-devel] [PATCH v8 02/10] HBitmap: Introduce "meta" bitmap to track bit changes

[John Snow]

From: Fam Zheng <famz@redhat.com>

Upon each bit toggle, the corresponding bit in the meta bitmap will be
set.

Signed-off-by: Fam Zheng <famz@redhat.com>
[Amended text inline. --js]
Reviewed-by: Max Reitz <mreitz@redhat.com>

Signed-off-by: John Snow <jsnow@redhat.com>
---
 include/qemu/hbitmap.h | 21 +++++++++++++++
 util/hbitmap.c         | 69 +++++++++++++++++++++++++++++++++++++++-----------
 2 files changed, 75 insertions(+), 15 deletions(-)

diff --git a/include/qemu/hbitmap.h b/include/qemu/hbitmap.h
index 8ab721e..1725919 100644
--- a/include/qemu/hbitmap.h
+++ b/include/qemu/hbitmap.h
@@ -178,6 +178,27 @@ void hbitmap_iter_init(HBitmapIter *hbi, const HBitmap *hb, uint64_t first);
  */
 unsigned long hbitmap_iter_skip_words(HBitmapIter *hbi);
 
+/* hbitmap_create_meta:
+ * Create a "meta" hbitmap to track dirtiness of the bits in this HBitmap.
+ * The caller owns the created bitmap and must call hbitmap_free_meta(hb) to
+ * free it.
+ *
+ * Currently, we only guarantee that if a bit in the hbitmap is changed it
+ * will be reflected in the meta bitmap, but we do not yet guarantee the
+ * opposite.
+ *
+ * @hb: The HBitmap to operate on.
+ * @chunk_size: How many bits in @hb does one bit in the meta track.
+ */
+HBitmap *hbitmap_create_meta(HBitmap *hb, int chunk_size);
+
+/* hbitmap_free_meta:
+ * Free the meta bitmap of @hb.
+ *
+ * @hb: The HBitmap whose meta bitmap should be freed.
+ */
+void hbitmap_free_meta(HBitmap *hb);
+
 /**
  * hbitmap_iter_next:
  * @hbi: HBitmapIter to operate on.
diff --git a/util/hbitmap.c b/util/hbitmap.c
index 99fd2ba..f303975 100644
--- a/util/hbitmap.c
+++ b/util/hbitmap.c
@@ -78,6 +78,9 @@ struct HBitmap {
      */
     int granularity;
 
+    /* A meta dirty bitmap to track the dirtiness of bits in this HBitmap. */
+    HBitmap *meta;
+
     /* A number of progressively less coarse bitmaps (i.e. level 0 is the
      * coarsest).  Each bit in level N represents a word in level N+1 that
      * has a set bit, except the last level where each bit represents the
@@ -209,25 +212,27 @@ static uint64_t hb_count_between(HBitmap *hb, uint64_t start, uint64_t last)
 }
 
 /* Setting starts at the last layer and propagates up if an element
- * changes from zero to non-zero.
+ * changes.
  */
 static inline bool hb_set_elem(unsigned long *elem, uint64_t start, uint64_t last)
 {
     unsigned long mask;
-    bool changed;
+    unsigned long old;
 
     assert((last >> BITS_PER_LEVEL) == (start >> BITS_PER_LEVEL));
     assert(start <= last);
 
     mask = 2UL << (last & (BITS_PER_LONG - 1));
     mask -= 1UL << (start & (BITS_PER_LONG - 1));
-    changed = (*elem == 0);
+    old = *elem;
     *elem |= mask;
-    return changed;
+    return old != *elem;
 }
 
-/* The recursive workhorse (the depth is limited to HBITMAP_LEVELS)... */
-static void hb_set_between(HBitmap *hb, int level, uint64_t start, uint64_t last)
+/* The recursive workhorse (the depth is limited to HBITMAP_LEVELS)...
+ * Returns true if at least one bit is changed. */
+static bool hb_set_between(HBitmap *hb, int level, uint64_t start,
+                           uint64_t last)
 {
     size_t pos = start >> BITS_PER_LEVEL;
     size_t lastpos = last >> BITS_PER_LEVEL;
@@ -256,23 +261,28 @@ static void hb_set_between(HBitmap *hb, int level, uint64_t start, uint64_t last
     if (level > 0 && changed) {
         hb_set_between(hb, level - 1, pos, lastpos);
     }
+    return changed;
 }
 
 void hbitmap_set(HBitmap *hb, uint64_t start, uint64_t count)
 {
     /* Compute range in the last layer.  */
+    uint64_t first, n;
     uint64_t last = start + count - 1;
 
     trace_hbitmap_set(hb, start, count,
                       start >> hb->granularity, last >> hb->granularity);
 
-    start >>= hb->granularity;
+    first = start >> hb->granularity;
     last >>= hb->granularity;
-    count = last - start + 1;
     assert(last < hb->size);
+    n = last - first + 1;
 
-    hb->count += count - hb_count_between(hb, start, last);
-    hb_set_between(hb, HBITMAP_LEVELS - 1, start, last);
+    hb->count += n - hb_count_between(hb, first, last);
+    if (hb_set_between(hb, HBITMAP_LEVELS - 1, first, last) &&
+        hb->meta) {
+        hbitmap_set(hb->meta, start, count);
+    }
 }
 
 /* Resetting works the other way round: propagate up if the new
@@ -293,8 +303,10 @@ static inline bool hb_reset_elem(unsigned long *elem, uint64_t start, uint64_t l
     return blanked;
 }
 
-/* The recursive workhorse (the depth is limited to HBITMAP_LEVELS)... */
-static void hb_reset_between(HBitmap *hb, int level, uint64_t start, uint64_t last)
+/* The recursive workhorse (the depth is limited to HBITMAP_LEVELS)...
+ * Returns true if at least one bit is changed. */
+static bool hb_reset_between(HBitmap *hb, int level, uint64_t start,
+                             uint64_t last)
 {
     size_t pos = start >> BITS_PER_LEVEL;
     size_t lastpos = last >> BITS_PER_LEVEL;
@@ -337,22 +349,29 @@ static void hb_reset_between(HBitmap *hb, int level, uint64_t start, uint64_t la
     if (level > 0 && changed) {
         hb_reset_between(hb, level - 1, pos, lastpos);
     }
+
+    return changed;
+
 }
 
 void hbitmap_reset(HBitmap *hb, uint64_t start, uint64_t count)
 {
     /* Compute range in the last layer.  */
+    uint64_t first;
     uint64_t last = start + count - 1;
 
     trace_hbitmap_reset(hb, start, count,
                         start >> hb->granularity, last >> hb->granularity);
 
-    start >>= hb->granularity;
+    first = start >> hb->granularity;
     last >>= hb->granularity;
     assert(last < hb->size);
 
-    hb->count -= hb_count_between(hb, start, last);
-    hb_reset_between(hb, HBITMAP_LEVELS - 1, start, last);
+    hb->count -= hb_count_between(hb, first, last);
+    if (hb_reset_between(hb, HBITMAP_LEVELS - 1, first, last) &&
+        hb->meta) {
+        hbitmap_set(hb->meta, start, count);
+    }
 }
 
 void hbitmap_reset_all(HBitmap *hb)
@@ -381,6 +400,7 @@ bool hbitmap_get(const HBitmap *hb, uint64_t item)
 void hbitmap_free(HBitmap *hb)
 {
     unsigned i;
+    assert(!hb->meta);
     for (i = HBITMAP_LEVELS; i-- > 0; ) {
         g_free(hb->levels[i]);
     }
@@ -458,6 +478,9 @@ void hbitmap_truncate(HBitmap *hb, uint64_t size)
                    (size - old) * sizeof(*hb->levels[i]));
         }
     }
+    if (hb->meta) {
+        hbitmap_truncate(hb->meta, hb->size << hb->granularity);
+    }
 }
 
 
@@ -493,3 +516,19 @@ bool hbitmap_merge(HBitmap *a, const HBitmap *b)
 
     return true;
 }
+
+HBitmap *hbitmap_create_meta(HBitmap *hb, int chunk_size)
+{
+    assert(!(chunk_size & (chunk_size - 1)));
+    assert(!hb->meta);
+    hb->meta = hbitmap_alloc(hb->size << hb->granularity,
+                             hb->granularity + ctz32(chunk_size));
+    return hb->meta;
+}
+
+void hbitmap_free_meta(HBitmap *hb)
+{
+    assert(hb->meta);
+    hbitmap_free(hb->meta);
+    hb->meta = NULL;
+}
-- 
2.7.4

[Qemu-devel] [PATCH v8 03/10] tests: Add test code for meta bitmap

[John Snow]

From: Fam Zheng <famz@redhat.com>

Signed-off-by: Fam Zheng <famz@redhat.com>
Reviewed-by: John Snow <jsnow@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: John Snow <jsnow@redhat.com>
---
 tests/test-hbitmap.c | 116 +++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 116 insertions(+)

diff --git a/tests/test-hbitmap.c b/tests/test-hbitmap.c
index c0e9895..e3abde1 100644
--- a/tests/test-hbitmap.c
+++ b/tests/test-hbitmap.c
@@ -11,6 +11,7 @@
 
 #include "qemu/osdep.h"
 #include "qemu/hbitmap.h"
+#include "block/block.h"
 
 #define LOG_BITS_PER_LONG          (BITS_PER_LONG == 32 ? 5 : 6)
 
@@ -20,6 +21,7 @@
 
 typedef struct TestHBitmapData {
     HBitmap       *hb;
+    HBitmap       *meta;
     unsigned long *bits;
     size_t         size;
     size_t         old_size;
@@ -91,6 +93,14 @@ static void hbitmap_test_init(TestHBitmapData *data,
     }
 }
 
+static void hbitmap_test_init_meta(TestHBitmapData *data,
+                                   uint64_t size, int granularity,
+                                   int meta_chunk)
+{
+    hbitmap_test_init(data, size, granularity);
+    data->meta = hbitmap_create_meta(data->hb, meta_chunk);
+}
+
 static inline size_t hbitmap_test_array_size(size_t bits)
 {
     size_t n = DIV_ROUND_UP(bits, BITS_PER_LONG);
@@ -133,6 +143,9 @@ static void hbitmap_test_teardown(TestHBitmapData *data,
                                   const void *unused)
 {
     if (data->hb) {
+        if (data->meta) {
+            hbitmap_free_meta(data->hb);
+        }
         hbitmap_free(data->hb);
         data->hb = NULL;
     }
@@ -634,6 +647,103 @@ static void test_hbitmap_truncate_shrink_large(TestHBitmapData *data,
     hbitmap_test_truncate(data, size, -diff, 0);
 }
 
+static void hbitmap_check_meta(TestHBitmapData *data,
+                               int64_t start, int count)
+{
+    int64_t i;
+
+    for (i = 0; i < data->size; i++) {
+        if (i >= start && i < start + count) {
+            g_assert(hbitmap_get(data->meta, i));
+        } else {
+            g_assert(!hbitmap_get(data->meta, i));
+        }
+    }
+}
+
+static void hbitmap_test_meta(TestHBitmapData *data,
+                              int64_t start, int count,
+                              int64_t check_start, int check_count)
+{
+    hbitmap_reset_all(data->hb);
+    hbitmap_reset_all(data->meta);
+
+    /* Test "unset" -> "unset" will not update meta. */
+    hbitmap_reset(data->hb, start, count);
+    hbitmap_check_meta(data, 0, 0);
+
+    /* Test "unset" -> "set" will update meta */
+    hbitmap_set(data->hb, start, count);
+    hbitmap_check_meta(data, check_start, check_count);
+
+    /* Test "set" -> "set" will not update meta */
+    hbitmap_reset_all(data->meta);
+    hbitmap_set(data->hb, start, count);
+    hbitmap_check_meta(data, 0, 0);
+
+    /* Test "set" -> "unset" will update meta */
+    hbitmap_reset_all(data->meta);
+    hbitmap_reset(data->hb, start, count);
+    hbitmap_check_meta(data, check_start, check_count);
+}
+
+static void hbitmap_test_meta_do(TestHBitmapData *data, int chunk_size)
+{
+    uint64_t size = chunk_size * 100;
+    hbitmap_test_init_meta(data, size, 0, chunk_size);
+
+    hbitmap_test_meta(data, 0, 1, 0, chunk_size);
+    hbitmap_test_meta(data, 0, chunk_size, 0, chunk_size);
+    hbitmap_test_meta(data, chunk_size - 1, 1, 0, chunk_size);
+    hbitmap_test_meta(data, chunk_size - 1, 2, 0, chunk_size * 2);
+    hbitmap_test_meta(data, chunk_size - 1, chunk_size + 1, 0, chunk_size * 2);
+    hbitmap_test_meta(data, chunk_size - 1, chunk_size + 2, 0, chunk_size * 3);
+    hbitmap_test_meta(data, 7 * chunk_size - 1, chunk_size + 2,
+                      6 * chunk_size, chunk_size * 3);
+    hbitmap_test_meta(data, size - 1, 1, size - chunk_size, chunk_size);
+    hbitmap_test_meta(data, 0, size, 0, size);
+}
+
+static void test_hbitmap_meta_byte(TestHBitmapData *data, const void *unused)
+{
+    hbitmap_test_meta_do(data, BITS_PER_BYTE);
+}
+
+static void test_hbitmap_meta_word(TestHBitmapData *data, const void *unused)
+{
+    hbitmap_test_meta_do(data, BITS_PER_LONG);
+}
+
+static void test_hbitmap_meta_sector(TestHBitmapData *data, const void *unused)
+{
+    hbitmap_test_meta_do(data, BDRV_SECTOR_SIZE * BITS_PER_BYTE);
+}
+
+/**
+ * Create an HBitmap and test set/unset.
+ */
+static void test_hbitmap_meta_one(TestHBitmapData *data, const void *unused)
+{
+    int i;
+    int64_t offsets[] = {
+        0, 1, L1 - 1, L1, L1 + 1, L2 - 1, L2, L2 + 1, L3 - 1, L3, L3 + 1
+    };
+
+    hbitmap_test_init_meta(data, L3 * 2, 0, 1);
+    for (i = 0; i < ARRAY_SIZE(offsets); i++) {
+        hbitmap_test_meta(data, offsets[i], 1, offsets[i], 1);
+        hbitmap_test_meta(data, offsets[i], L1, offsets[i], L1);
+        hbitmap_test_meta(data, offsets[i], L2, offsets[i], L2);
+    }
+}
+
+static void test_hbitmap_meta_zero(TestHBitmapData *data, const void *unused)
+{
+    hbitmap_test_init_meta(data, 0, 0, 1);
+
+    hbitmap_check_meta(data, 0, 0);
+}
+
 static void hbitmap_test_add(const char *testpath,
                                    void (*test_func)(TestHBitmapData *data, const void *user_data))
 {
@@ -683,6 +793,12 @@ int main(int argc, char **argv)
                      test_hbitmap_truncate_grow_large);
     hbitmap_test_add("/hbitmap/truncate/shrink/large",
                      test_hbitmap_truncate_shrink_large);
+
+    hbitmap_test_add("/hbitmap/meta/zero", test_hbitmap_meta_zero);
+    hbitmap_test_add("/hbitmap/meta/one", test_hbitmap_meta_one);
+    hbitmap_test_add("/hbitmap/meta/byte", test_hbitmap_meta_byte);
+    hbitmap_test_add("/hbitmap/meta/word", test_hbitmap_meta_word);
+    hbitmap_test_add("/hbitmap/meta/sector", test_hbitmap_meta_sector);
     g_test_run();
 
     return 0;
-- 
2.7.4

[Qemu-devel] [PATCH v8 04/10] block: Support meta dirty bitmap

[John Snow]

From: Fam Zheng <famz@redhat.com>

The added group of operations enables tracking of the changed bits in
the dirty bitmap.

Signed-off-by: Fam Zheng <famz@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: John Snow <jsnow@redhat.com>
---
 block/dirty-bitmap.c         | 52 ++++++++++++++++++++++++++++++++++++++++++++
 include/block/dirty-bitmap.h |  9 ++++++++
 2 files changed, 61 insertions(+)

diff --git a/block/dirty-bitmap.c b/block/dirty-bitmap.c
index c572dfa..9c6febb 100644
--- a/block/dirty-bitmap.c
+++ b/block/dirty-bitmap.c
@@ -38,6 +38,7 @@
  */
 struct BdrvDirtyBitmap {
     HBitmap *bitmap;            /* Dirty sector bitmap implementation */
+    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) */
@@ -103,6 +104,56 @@ BdrvDirtyBitmap *bdrv_create_dirty_bitmap(BlockDriverState *bs,
     return bitmap;
 }
 
+/* bdrv_create_meta_dirty_bitmap
+ *
+ * Create a meta dirty bitmap that tracks the changes of bits in @bitmap. I.e.
+ * when a dirty status bit in @bitmap is changed (either from reset to set or
+ * the other way around), its respective meta dirty bitmap bit will be marked
+ * dirty as well.
+ *
+ * @bitmap: the block dirty bitmap for which to create a meta dirty bitmap.
+ * @chunk_size: how many bytes of bitmap data does each bit in the meta bitmap
+ * track.
+ */
+void bdrv_create_meta_dirty_bitmap(BdrvDirtyBitmap *bitmap,
+                                   int chunk_size)
+{
+    assert(!bitmap->meta);
+    bitmap->meta = hbitmap_create_meta(bitmap->bitmap,
+                                       chunk_size * BITS_PER_BYTE);
+}
+
+void bdrv_release_meta_dirty_bitmap(BdrvDirtyBitmap *bitmap)
+{
+    assert(bitmap->meta);
+    hbitmap_free_meta(bitmap->bitmap);
+    bitmap->meta = NULL;
+}
+
+int bdrv_dirty_bitmap_get_meta(BlockDriverState *bs,
+                               BdrvDirtyBitmap *bitmap, int64_t sector,
+                               int nb_sectors)
+{
+    uint64_t i;
+    int sectors_per_bit = 1 << hbitmap_granularity(bitmap->meta);
+
+    /* To optimize: we can make hbitmap to internally check the range in a
+     * coarse level, or at least do it word by word. */
+    for (i = sector; i < sector + nb_sectors; i += sectors_per_bit) {
+        if (hbitmap_get(bitmap->meta, i)) {
+            return true;
+        }
+    }
+    return false;
+}
+
+void bdrv_dirty_bitmap_reset_meta(BlockDriverState *bs,
+                                  BdrvDirtyBitmap *bitmap, int64_t sector,
+                                  int nb_sectors)
+{
+    hbitmap_reset(bitmap->meta, sector, nb_sectors);
+}
+
 bool bdrv_dirty_bitmap_frozen(BdrvDirtyBitmap *bitmap)
 {
     return bitmap->successor;
@@ -233,6 +284,7 @@ static void bdrv_do_release_matching_dirty_bitmap(BlockDriverState *bs,
         if ((!bitmap || bm == bitmap) && (!only_named || bm->name)) {
             assert(!bm->active_iterators);
             assert(!bdrv_dirty_bitmap_frozen(bm));
+            assert(!bm->meta);
             QLIST_REMOVE(bm, list);
             hbitmap_free(bm->bitmap);
             g_free(bm->name);
diff --git a/include/block/dirty-bitmap.h b/include/block/dirty-bitmap.h
index 0ef927d..69c500b 100644
--- a/include/block/dirty-bitmap.h
+++ b/include/block/dirty-bitmap.h
@@ -8,6 +8,9 @@ BdrvDirtyBitmap *bdrv_create_dirty_bitmap(BlockDriverState *bs,
                                           uint32_t granularity,
                                           const char *name,
                                           Error **errp);
+void bdrv_create_meta_dirty_bitmap(BdrvDirtyBitmap *bitmap,
+                                   int chunk_size);
+void bdrv_release_meta_dirty_bitmap(BdrvDirtyBitmap *bitmap);
 int bdrv_dirty_bitmap_create_successor(BlockDriverState *bs,
                                        BdrvDirtyBitmap *bitmap,
                                        Error **errp);
@@ -36,6 +39,12 @@ void bdrv_set_dirty_bitmap(BdrvDirtyBitmap *bitmap,
                            int64_t cur_sector, int64_t nr_sectors);
 void bdrv_reset_dirty_bitmap(BdrvDirtyBitmap *bitmap,
                              int64_t cur_sector, int64_t nr_sectors);
+int bdrv_dirty_bitmap_get_meta(BlockDriverState *bs,
+                               BdrvDirtyBitmap *bitmap, int64_t sector,
+                               int nb_sectors);
+void bdrv_dirty_bitmap_reset_meta(BlockDriverState *bs,
+                                  BdrvDirtyBitmap *bitmap, int64_t sector,
+                                  int nb_sectors);
 BdrvDirtyBitmapIter *bdrv_dirty_iter_new(BdrvDirtyBitmap *bitmap,
                                          uint64_t first_sector);
 void bdrv_dirty_iter_free(BdrvDirtyBitmapIter *iter);
-- 
2.7.4

[Qemu-devel] [PATCH v8 05/10] block: Add two dirty bitmap getters

[John Snow]

From: Fam Zheng <famz@redhat.com>

For dirty bitmap users to get the size and the name of a
BdrvDirtyBitmap.

Signed-off-by: Fam Zheng <famz@redhat.com>
Reviewed-by: John Snow <jsnow@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: John Snow <jsnow@redhat.com>
---
 block/dirty-bitmap.c         | 10 ++++++++++
 include/block/dirty-bitmap.h |  2 ++
 2 files changed, 12 insertions(+)

diff --git a/block/dirty-bitmap.c b/block/dirty-bitmap.c
index 9c6febb..860acc9 100644
--- a/block/dirty-bitmap.c
+++ b/block/dirty-bitmap.c
@@ -154,6 +154,16 @@ void bdrv_dirty_bitmap_reset_meta(BlockDriverState *bs,
     hbitmap_reset(bitmap->meta, sector, nb_sectors);
 }
 
+int64_t bdrv_dirty_bitmap_size(const BdrvDirtyBitmap *bitmap)
+{
+    return bitmap->size;
+}
+
+const char *bdrv_dirty_bitmap_name(const BdrvDirtyBitmap *bitmap)
+{
+    return bitmap->name;
+}
+
 bool bdrv_dirty_bitmap_frozen(BdrvDirtyBitmap *bitmap)
 {
     return bitmap->successor;
diff --git a/include/block/dirty-bitmap.h b/include/block/dirty-bitmap.h
index 69c500b..c4e7858 100644
--- a/include/block/dirty-bitmap.h
+++ b/include/block/dirty-bitmap.h
@@ -32,6 +32,8 @@ uint32_t bdrv_get_default_bitmap_granularity(BlockDriverState *bs);
 uint32_t bdrv_dirty_bitmap_granularity(BdrvDirtyBitmap *bitmap);
 bool bdrv_dirty_bitmap_enabled(BdrvDirtyBitmap *bitmap);
 bool bdrv_dirty_bitmap_frozen(BdrvDirtyBitmap *bitmap);
+const char *bdrv_dirty_bitmap_name(const BdrvDirtyBitmap *bitmap);
+int64_t bdrv_dirty_bitmap_size(const BdrvDirtyBitmap *bitmap);
 DirtyBitmapStatus bdrv_dirty_bitmap_status(BdrvDirtyBitmap *bitmap);
 int bdrv_get_dirty(BlockDriverState *bs, BdrvDirtyBitmap *bitmap,
                    int64_t sector);
-- 
2.7.4

[Qemu-devel] [PATCH v8 06/10] block: Assert that bdrv_release_dirty_bitmap succeeded

[John Snow]

From: Fam Zheng <famz@redhat.com>

We use a loop over bs->dirty_bitmaps to make sure the caller is
only releasing a bitmap owned by bs. Let's also assert that in this case
the caller is releasing a bitmap that does exist.

Signed-off-by: Fam Zheng <famz@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: John Snow <jsnow@redhat.com>
---
 block/dirty-bitmap.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/block/dirty-bitmap.c b/block/dirty-bitmap.c
index 860acc9..31d5296 100644
--- a/block/dirty-bitmap.c
+++ b/block/dirty-bitmap.c
@@ -305,6 +305,9 @@ static void bdrv_do_release_matching_dirty_bitmap(BlockDriverState *bs,
             }
         }
     }
+    if (bitmap) {
+        abort();
+    }
 }
 
 void bdrv_release_dirty_bitmap(BlockDriverState *bs, BdrvDirtyBitmap *bitmap)
-- 
2.7.4

[Qemu-devel] [PATCH v8 07/10] hbitmap: serialization

[John Snow]

From: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>

Functions to serialize / deserialize(restore) HBitmap. HBitmap should be
saved to linear sequence of bits independently of endianness and bitmap
array element (unsigned long) size. Therefore Little Endian is chosen.

These functions are appropriate for dirty bitmap migration, restoring
the bitmap in several steps is available. To save performance, every
step writes only the last level of the bitmap. All other levels are
restored by hbitmap_deserialize_finish() as a last step of restoring.
So, HBitmap is inconsistent while restoring.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
[Fix left shift operand to 1UL; add "finish" parameter. - Fam]
Signed-off-by: Fam Zheng <famz@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>

Signed-off-by: John Snow <jsnow@redhat.com>
---
 include/qemu/hbitmap.h |  79 ++++++++++++++++++++++++++++
 util/hbitmap.c         | 137 +++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 216 insertions(+)

diff --git a/include/qemu/hbitmap.h b/include/qemu/hbitmap.h
index 1725919..eb46475 100644
--- a/include/qemu/hbitmap.h
+++ b/include/qemu/hbitmap.h
@@ -146,6 +146,85 @@ void hbitmap_reset_all(HBitmap *hb);
 bool hbitmap_get(const HBitmap *hb, uint64_t item);
 
 /**
+ * hbitmap_serialization_granularity:
+ * @hb: HBitmap to operate on.
+ *
+ * Granularity of serialization chunks, used by other serialization functions.
+ * For every chunk:
+ * 1. Chunk start should be aligned to this granularity.
+ * 2. Chunk size should be aligned too, except for last chunk (for which
+ *      start + count == hb->size)
+ */
+uint64_t hbitmap_serialization_granularity(const HBitmap *hb);
+
+/**
+ * hbitmap_serialization_size:
+ * @hb: HBitmap to operate on.
+ * @start: Starting bit
+ * @count: Number of bits
+ *
+ * Return number of bytes hbitmap_(de)serialize_part needs
+ */
+uint64_t hbitmap_serialization_size(const HBitmap *hb,
+                                    uint64_t start, uint64_t count);
+
+/**
+ * hbitmap_serialize_part
+ * @hb: HBitmap to operate on.
+ * @buf: Buffer to store serialized bitmap.
+ * @start: First bit to store.
+ * @count: Number of bits to store.
+ *
+ * Stores HBitmap data corresponding to given region. The format of saved data
+ * is linear sequence of bits, so it can be used by hbitmap_deserialize_part
+ * independently of endianness and size of HBitmap level array elements
+ */
+void hbitmap_serialize_part(const HBitmap *hb, uint8_t *buf,
+                            uint64_t start, uint64_t count);
+
+/**
+ * hbitmap_deserialize_part
+ * @hb: HBitmap to operate on.
+ * @buf: Buffer to restore bitmap data from.
+ * @start: First bit to restore.
+ * @count: Number of bits to restore.
+ * @finish: Whether to call hbitmap_deserialize_finish automatically.
+ *
+ * Restores HBitmap data corresponding to given region. The format is the same
+ * as for hbitmap_serialize_part.
+ *
+ * If @finish is false, caller must call hbitmap_serialize_finish before using
+ * the bitmap.
+ */
+void hbitmap_deserialize_part(HBitmap *hb, uint8_t *buf,
+                              uint64_t start, uint64_t count,
+                              bool finish);
+
+/**
+ * hbitmap_deserialize_zeroes
+ * @hb: HBitmap to operate on.
+ * @start: First bit to restore.
+ * @count: Number of bits to restore.
+ * @finish: Whether to call hbitmap_deserialize_finish automatically.
+ *
+ * Fills the bitmap with zeroes.
+ *
+ * If @finish is false, caller must call hbitmap_serialize_finish before using
+ * the bitmap.
+ */
+void hbitmap_deserialize_zeroes(HBitmap *hb, uint64_t start, uint64_t count,
+                                bool finish);
+
+/**
+ * hbitmap_deserialize_finish
+ * @hb: HBitmap to operate on.
+ *
+ * Repair HBitmap after calling hbitmap_deserialize_data. Actually, all HBitmap
+ * layers are restored here.
+ */
+void hbitmap_deserialize_finish(HBitmap *hb);
+
+/**
  * hbitmap_free:
  * @hb: HBitmap to operate on.
  *
diff --git a/util/hbitmap.c b/util/hbitmap.c
index f303975..6a13c12 100644
--- a/util/hbitmap.c
+++ b/util/hbitmap.c
@@ -397,6 +397,143 @@ bool hbitmap_get(const HBitmap *hb, uint64_t item)
     return (hb->levels[HBITMAP_LEVELS - 1][pos >> BITS_PER_LEVEL] & bit) != 0;
 }
 
+uint64_t hbitmap_serialization_granularity(const HBitmap *hb)
+{
+    /* Require at least 64 bit granularity to be safe on both 64 bit and 32 bit
+     * hosts. */
+    return 64 << hb->granularity;
+}
+
+/* Start should be aligned to serialization granularity, chunk size should be
+ * aligned to serialization granularity too, except for last chunk.
+ */
+static void serialization_chunk(const HBitmap *hb,
+                                uint64_t start, uint64_t count,
+                                unsigned long **first_el, size_t *el_count)
+{
+    uint64_t last = start + count - 1;
+    uint64_t gran = hbitmap_serialization_granularity(hb);
+
+    assert((start & (gran - 1)) == 0);
+    assert((last >> hb->granularity) < hb->size);
+    if ((last >> hb->granularity) != hb->size - 1) {
+        assert((count & (gran - 1)) == 0);
+    }
+
+    start = (start >> hb->granularity) >> BITS_PER_LEVEL;
+    last = (last >> hb->granularity) >> BITS_PER_LEVEL;
+
+    *first_el = &hb->levels[HBITMAP_LEVELS - 1][start];
+    *el_count = last - start + 1;
+}
+
+uint64_t hbitmap_serialization_size(const HBitmap *hb,
+                                    uint64_t start, uint64_t count)
+{
+    uint64_t el_count;
+    unsigned long *cur;
+
+    if (!count) {
+        return 0;
+    }
+    serialization_chunk(hb, start, count, &cur, &el_count);
+
+    return el_count * sizeof(unsigned long);
+}
+
+void hbitmap_serialize_part(const HBitmap *hb, uint8_t *buf,
+                            uint64_t start, uint64_t count)
+{
+    uint64_t el_count;
+    unsigned long *cur, *end;
+
+    if (!count) {
+        return;
+    }
+    serialization_chunk(hb, start, count, &cur, &el_count);
+    end = cur + el_count;
+
+    while (cur != end) {
+        unsigned long el =
+            (BITS_PER_LONG == 32 ? cpu_to_le32(*cur) : cpu_to_le64(*cur));
+
+        memcpy(buf, &el, sizeof(el));
+        buf += sizeof(el);
+        cur++;
+    }
+}
+
+void hbitmap_deserialize_part(HBitmap *hb, uint8_t *buf,
+                              uint64_t start, uint64_t count,
+                              bool finish)
+{
+    uint64_t el_count;
+    unsigned long *cur, *end;
+
+    if (!count) {
+        return;
+    }
+    serialization_chunk(hb, start, count, &cur, &el_count);
+    end = cur + el_count;
+
+    while (cur != end) {
+        memcpy(cur, buf, sizeof(*cur));
+
+        if (BITS_PER_LONG == 32) {
+            le32_to_cpus((uint32_t *)cur);
+        } else {
+            le64_to_cpus((uint64_t *)cur);
+        }
+
+        buf += sizeof(unsigned long);
+        cur++;
+    }
+    if (finish) {
+        hbitmap_deserialize_finish(hb);
+    }
+}
+
+void hbitmap_deserialize_zeroes(HBitmap *hb, uint64_t start, uint64_t count,
+                                bool finish)
+{
+    uint64_t el_count;
+    unsigned long *first;
+
+    if (!count) {
+        return;
+    }
+    serialization_chunk(hb, start, count, &first, &el_count);
+
+    memset(first, 0, el_count * sizeof(unsigned long));
+    if (finish) {
+        hbitmap_deserialize_finish(hb);
+    }
+}
+
+void hbitmap_deserialize_finish(HBitmap *bitmap)
+{
+    int64_t i, size, prev_size;
+    int lev;
+
+    /* restore levels starting from penultimate to zero level, assuming
+     * that the last level is ok */
+    size = MAX((bitmap->size + BITS_PER_LONG - 1) >> BITS_PER_LEVEL, 1);
+    for (lev = HBITMAP_LEVELS - 1; lev-- > 0; ) {
+        prev_size = size;
+        size = MAX((size + BITS_PER_LONG - 1) >> BITS_PER_LEVEL, 1);
+        memset(bitmap->levels[lev], 0, size * sizeof(unsigned long));
+
+        for (i = 0; i < prev_size; ++i) {
+            if (bitmap->levels[lev + 1][i]) {
+                bitmap->levels[lev][i >> BITS_PER_LEVEL] |=
+                    1UL << (i & (BITS_PER_LONG - 1));
+            }
+        }
+    }
+
+    bitmap->levels[0][0] |= 1UL << (BITS_PER_LONG - 1);
+}
+
 void hbitmap_free(HBitmap *hb)
 {
     unsigned i;
-- 
2.7.4

[Qemu-devel] [PATCH v8 08/10] block: BdrvDirtyBitmap serialization interface

[John Snow]

From: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>

Several functions to provide necessary access to BdrvDirtyBitmap for
block-migration.c

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
[Add the "finish" parameters. - Fam]
Signed-off-by: Fam Zheng <famz@redhat.com>
Reviewed-by: John Snow <jsnow@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>

Signed-off-by: John Snow <jsnow@redhat.com>
---
 block/dirty-bitmap.c         | 37 +++++++++++++++++++++++++++++++++++++
 include/block/dirty-bitmap.h | 14 ++++++++++++++
 2 files changed, 51 insertions(+)

diff --git a/block/dirty-bitmap.c b/block/dirty-bitmap.c
index 31d5296..384146b 100644
--- a/block/dirty-bitmap.c
+++ b/block/dirty-bitmap.c
@@ -453,6 +453,43 @@ void bdrv_undo_clear_dirty_bitmap(BdrvDirtyBitmap *bitmap, HBitmap *in)
     hbitmap_free(tmp);
 }
 
+uint64_t bdrv_dirty_bitmap_serialization_size(const BdrvDirtyBitmap *bitmap,
+                                              uint64_t start, uint64_t count)
+{
+    return hbitmap_serialization_size(bitmap->bitmap, start, count);
+}
+
+uint64_t bdrv_dirty_bitmap_serialization_align(const BdrvDirtyBitmap *bitmap)
+{
+    return hbitmap_serialization_granularity(bitmap->bitmap);
+}
+
+void bdrv_dirty_bitmap_serialize_part(const BdrvDirtyBitmap *bitmap,
+                                      uint8_t *buf, uint64_t start,
+                                      uint64_t count)
+{
+    hbitmap_serialize_part(bitmap->bitmap, buf, start, count);
+}
+
+void bdrv_dirty_bitmap_deserialize_part(BdrvDirtyBitmap *bitmap,
+                                        uint8_t *buf, uint64_t start,
+                                        uint64_t count, bool finish)
+{
+    hbitmap_deserialize_part(bitmap->bitmap, buf, start, count, finish);
+}
+
+void bdrv_dirty_bitmap_deserialize_zeroes(BdrvDirtyBitmap *bitmap,
+                                          uint64_t start, uint64_t count,
+                                          bool finish)
+{
+    hbitmap_deserialize_zeroes(bitmap->bitmap, start, count, finish);
+}
+
+void bdrv_dirty_bitmap_deserialize_finish(BdrvDirtyBitmap *bitmap)
+{
+    hbitmap_deserialize_finish(bitmap->bitmap);
+}
+
 void bdrv_set_dirty(BlockDriverState *bs, int64_t cur_sector,
                     int64_t nr_sectors)
 {
diff --git a/include/block/dirty-bitmap.h b/include/block/dirty-bitmap.h
index c4e7858..efc2965 100644
--- a/include/block/dirty-bitmap.h
+++ b/include/block/dirty-bitmap.h
@@ -55,4 +55,18 @@ void bdrv_set_dirty_iter(BdrvDirtyBitmapIter *hbi, int64_t sector_num);
 int64_t bdrv_get_dirty_count(BdrvDirtyBitmap *bitmap);
 void bdrv_dirty_bitmap_truncate(BlockDriverState *bs);
 
+uint64_t bdrv_dirty_bitmap_serialization_size(const BdrvDirtyBitmap *bitmap,
+                                              uint64_t start, uint64_t count);
+uint64_t bdrv_dirty_bitmap_serialization_align(const BdrvDirtyBitmap *bitmap);
+void bdrv_dirty_bitmap_serialize_part(const BdrvDirtyBitmap *bitmap,
+                                      uint8_t *buf, uint64_t start,
+                                      uint64_t count);
+void bdrv_dirty_bitmap_deserialize_part(BdrvDirtyBitmap *bitmap,
+                                        uint8_t *buf, uint64_t start,
+                                        uint64_t count, bool finish);
+void bdrv_dirty_bitmap_deserialize_zeroes(BdrvDirtyBitmap *bitmap,
+                                          uint64_t start, uint64_t count,
+                                          bool finish);
+void bdrv_dirty_bitmap_deserialize_finish(BdrvDirtyBitmap *bitmap);
+
 #endif
-- 
2.7.4

[Qemu-devel] [PATCH v8 09/10] tests: Add test code for hbitmap serialization

[John Snow]

From: Fam Zheng <famz@redhat.com>

Signed-off-by: Fam Zheng <famz@redhat.com>
[Fixed minor constant issue. --js]
Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>

Signed-off-by: John Snow <jsnow@redhat.com>
---
 tests/test-hbitmap.c | 139 +++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 139 insertions(+)

diff --git a/tests/test-hbitmap.c b/tests/test-hbitmap.c
index e3abde1..0ed918c 100644
--- a/tests/test-hbitmap.c
+++ b/tests/test-hbitmap.c
@@ -11,6 +11,7 @@
 
 #include "qemu/osdep.h"
 #include "qemu/hbitmap.h"
+#include "qemu/bitmap.h"
 #include "block/block.h"
 
 #define LOG_BITS_PER_LONG          (BITS_PER_LONG == 32 ? 5 : 6)
@@ -737,6 +738,16 @@ static void test_hbitmap_meta_one(TestHBitmapData *data, const void *unused)
     }
 }
 
+static void test_hbitmap_serialize_granularity(TestHBitmapData *data,
+                                               const void *unused)
+{
+    int r;
+
+    hbitmap_test_init(data, L3 * 2, 3);
+    r = hbitmap_serialization_granularity(data->hb);
+    g_assert_cmpint(r, ==, 64 << 3);
+}
+
 static void test_hbitmap_meta_zero(TestHBitmapData *data, const void *unused)
 {
     hbitmap_test_init_meta(data, 0, 0, 1);
@@ -744,6 +755,125 @@ static void test_hbitmap_meta_zero(TestHBitmapData *data, const void *unused)
     hbitmap_check_meta(data, 0, 0);
 }
 
+static void hbitmap_test_serialize_range(TestHBitmapData *data,
+                                         uint8_t *buf, size_t buf_size,
+                                         uint64_t pos, uint64_t count)
+{
+    size_t i;
+
+    assert(hbitmap_granularity(data->hb) == 0);
+    hbitmap_reset_all(data->hb);
+    memset(buf, 0, buf_size);
+    if (count) {
+        hbitmap_set(data->hb, pos, count);
+    }
+    hbitmap_serialize_part(data->hb, buf, 0, data->size);
+    for (i = 0; i < data->size; i++) {
+        int is_set = test_bit(i, (unsigned long *)buf);
+        if (i >= pos && i < pos + count) {
+            g_assert(is_set);
+        } else {
+            g_assert(!is_set);
+        }
+    }
+    hbitmap_reset_all(data->hb);
+    hbitmap_deserialize_part(data->hb, buf, 0, data->size, true);
+
+    for (i = 0; i < data->size; i++) {
+        int is_set = hbitmap_get(data->hb, i);
+        if (i >= pos && i < pos + count) {
+            g_assert(is_set);
+        } else {
+            g_assert(!is_set);
+        }
+    }
+}
+
+static void test_hbitmap_serialize_basic(TestHBitmapData *data,
+                                         const void *unused)
+{
+    int i, j;
+    size_t buf_size;
+    uint8_t *buf;
+    uint64_t positions[] = { 0, 1, L1 - 1, L1, L2 - 1, L2, L2 + 1, L3 - 1 };
+    int num_positions = sizeof(positions) / sizeof(positions[0]);
+
+    hbitmap_test_init(data, L3, 0);
+    buf_size = hbitmap_serialization_size(data->hb, 0, data->size);
+    buf = g_malloc0(buf_size);
+
+    for (i = 0; i < num_positions; i++) {
+        for (j = 0; j < num_positions; j++) {
+            hbitmap_test_serialize_range(data, buf, buf_size,
+                                         positions[i],
+                                         MIN(positions[j], L3 - positions[i]));
+        }
+    }
+
+    g_free(buf);
+}
+
+static void test_hbitmap_serialize_part(TestHBitmapData *data,
+                                        const void *unused)
+{
+    int i, j, k;
+    size_t buf_size;
+    uint8_t *buf;
+    uint64_t positions[] = { 0, 1, L1 - 1, L1, L2 - 1, L2, L2 + 1, L3 - 1 };
+    int num_positions = sizeof(positions) / sizeof(positions[0]);
+
+    hbitmap_test_init(data, L3, 0);
+    buf_size = L2;
+    buf = g_malloc0(buf_size);
+
+    for (i = 0; i < num_positions; i++) {
+        hbitmap_set(data->hb, positions[i], 1);
+    }
+
+    for (i = 0; i < data->size; i += buf_size) {
+        hbitmap_serialize_part(data->hb, buf, i, buf_size);
+        for (j = 0; j < buf_size; j++) {
+            bool should_set = false;
+            for (k = 0; k < num_positions; k++) {
+                if (positions[k] == j + i) {
+                    should_set = true;
+                    break;
+                }
+            }
+            g_assert_cmpint(should_set, ==, test_bit(j, (unsigned long *)buf));
+        }
+    }
+
+    g_free(buf);
+}
+
+static void test_hbitmap_serialize_zeroes(TestHBitmapData *data,
+                                          const void *unused)
+{
+    int i;
+    HBitmapIter iter;
+    int64_t next;
+    uint64_t positions[] = { 0, L1, L2, L3 - L1};
+    int num_positions = sizeof(positions) / sizeof(positions[0]);
+
+    hbitmap_test_init(data, L3, 0);
+
+    for (i = 0; i < num_positions; i++) {
+        hbitmap_set(data->hb, positions[i], L1);
+    }
+
+    for (i = 0; i < num_positions; i++) {
+        hbitmap_deserialize_zeroes(data->hb, positions[i], L1, true);
+        hbitmap_iter_init(&iter, data->hb, 0);
+        next = hbitmap_iter_next(&iter);
+        if (i == num_positions - 1) {
+            g_assert_cmpint(next, ==, -1);
+        } else {
+            g_assert_cmpint(next, ==, positions[i + 1]);
+        }
+    }
+}
+
 static void hbitmap_test_add(const char *testpath,
                                    void (*test_func)(TestHBitmapData *data, const void *user_data))
 {
@@ -799,6 +929,15 @@ int main(int argc, char **argv)
     hbitmap_test_add("/hbitmap/meta/byte", test_hbitmap_meta_byte);
     hbitmap_test_add("/hbitmap/meta/word", test_hbitmap_meta_word);
     hbitmap_test_add("/hbitmap/meta/sector", test_hbitmap_meta_sector);
+
+    hbitmap_test_add("/hbitmap/serialize/granularity",
+                     test_hbitmap_serialize_granularity);
+    hbitmap_test_add("/hbitmap/serialize/basic",
+                     test_hbitmap_serialize_basic);
+    hbitmap_test_add("/hbitmap/serialize/part",
+                     test_hbitmap_serialize_part);
+    hbitmap_test_add("/hbitmap/serialize/zeroes",
+                     test_hbitmap_serialize_zeroes);
     g_test_run();
 
     return 0;
-- 
2.7.4

[Qemu-devel] [PATCH v8 10/10] block: More operations for meta dirty bitmap

[John Snow]

From: Fam Zheng <famz@redhat.com>

Callers can create an iterator of meta bitmap with
bdrv_dirty_meta_iter_new(), then use the bdrv_dirty_iter_* operations on
it. Meta iterators are also counted by bitmap->active_iterators.

Also add a couple of functions to retrieve granularity and count.

Signed-off-by: Fam Zheng <famz@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: John Snow <jsnow@redhat.com>
---
 block/dirty-bitmap.c         | 19 +++++++++++++++++++
 include/block/dirty-bitmap.h |  3 +++
 2 files changed, 22 insertions(+)

diff --git a/block/dirty-bitmap.c b/block/dirty-bitmap.c
index 384146b..519737c 100644
--- a/block/dirty-bitmap.c
+++ b/block/dirty-bitmap.c
@@ -393,6 +393,11 @@ uint32_t bdrv_dirty_bitmap_granularity(BdrvDirtyBitmap *bitmap)
     return BDRV_SECTOR_SIZE << hbitmap_granularity(bitmap->bitmap);
 }
 
+uint32_t bdrv_dirty_bitmap_meta_granularity(BdrvDirtyBitmap *bitmap)
+{
+    return BDRV_SECTOR_SIZE << hbitmap_granularity(bitmap->meta);
+}
+
 BdrvDirtyBitmapIter *bdrv_dirty_iter_new(BdrvDirtyBitmap *bitmap,
                                          uint64_t first_sector)
 {
@@ -403,6 +408,15 @@ BdrvDirtyBitmapIter *bdrv_dirty_iter_new(BdrvDirtyBitmap *bitmap,
     return iter;
 }
 
+BdrvDirtyBitmapIter *bdrv_dirty_meta_iter_new(BdrvDirtyBitmap *bitmap)
+{
+    BdrvDirtyBitmapIter *iter = g_new(BdrvDirtyBitmapIter, 1);
+    hbitmap_iter_init(&iter->hbi, bitmap->meta, 0);
+    iter->bitmap = bitmap;
+    bitmap->active_iterators++;
+    return iter;
+}
+
 void bdrv_dirty_iter_free(BdrvDirtyBitmapIter *iter)
 {
     if (!iter) {
@@ -514,3 +528,8 @@ int64_t bdrv_get_dirty_count(BdrvDirtyBitmap *bitmap)
 {
     return hbitmap_count(bitmap->bitmap);
 }
+
+int64_t bdrv_get_meta_dirty_count(BdrvDirtyBitmap *bitmap)
+{
+    return hbitmap_count(bitmap->meta);
+}
diff --git a/include/block/dirty-bitmap.h b/include/block/dirty-bitmap.h
index efc2965..9dea14b 100644
--- a/include/block/dirty-bitmap.h
+++ b/include/block/dirty-bitmap.h
@@ -30,6 +30,7 @@ void bdrv_enable_dirty_bitmap(BdrvDirtyBitmap *bitmap);
 BlockDirtyInfoList *bdrv_query_dirty_bitmaps(BlockDriverState *bs);
 uint32_t bdrv_get_default_bitmap_granularity(BlockDriverState *bs);
 uint32_t bdrv_dirty_bitmap_granularity(BdrvDirtyBitmap *bitmap);
+uint32_t bdrv_dirty_bitmap_meta_granularity(BdrvDirtyBitmap *bitmap);
 bool bdrv_dirty_bitmap_enabled(BdrvDirtyBitmap *bitmap);
 bool bdrv_dirty_bitmap_frozen(BdrvDirtyBitmap *bitmap);
 const char *bdrv_dirty_bitmap_name(const BdrvDirtyBitmap *bitmap);
@@ -47,12 +48,14 @@ int bdrv_dirty_bitmap_get_meta(BlockDriverState *bs,
 void bdrv_dirty_bitmap_reset_meta(BlockDriverState *bs,
                                   BdrvDirtyBitmap *bitmap, int64_t sector,
                                   int nb_sectors);
+BdrvDirtyBitmapIter *bdrv_dirty_meta_iter_new(BdrvDirtyBitmap *bitmap);
 BdrvDirtyBitmapIter *bdrv_dirty_iter_new(BdrvDirtyBitmap *bitmap,
                                          uint64_t first_sector);
 void bdrv_dirty_iter_free(BdrvDirtyBitmapIter *iter);
 int64_t bdrv_dirty_iter_next(BdrvDirtyBitmapIter *iter);
 void bdrv_set_dirty_iter(BdrvDirtyBitmapIter *hbi, int64_t sector_num);
 int64_t bdrv_get_dirty_count(BdrvDirtyBitmap *bitmap);
+int64_t bdrv_get_meta_dirty_count(BdrvDirtyBitmap *bitmap);
 void bdrv_dirty_bitmap_truncate(BlockDriverState *bs);
 
 uint64_t bdrv_dirty_bitmap_serialization_size(const BdrvDirtyBitmap *bitmap,
-- 
2.7.4

Re: [Qemu-devel] [PATCH v8 04/10] block: Support meta dirty bitmap

[Max Reitz]

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On 02.08.2016 02:12, John Snow wrote:
> From: Fam Zheng <famz@redhat.com>
> 
> The added group of operations enables tracking of the changed bits in
> the dirty bitmap.
> 
> Signed-off-by: Fam Zheng <famz@redhat.com>
> Reviewed-by: Max Reitz <mreitz@redhat.com>

Indeed. :-)

Max

> Signed-off-by: John Snow <jsnow@redhat.com>
> ---
>  block/dirty-bitmap.c         | 52 ++++++++++++++++++++++++++++++++++++++++++++
>  include/block/dirty-bitmap.h |  9 ++++++++
>  2 files changed, 61 insertions(+)



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Re: [Qemu-devel] [PATCH v8 00/10] Dirty bitmap changes for migration/persistence work

[Max Reitz]

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On 02.08.2016 02:12, John Snow wrote:
> Key:
> [----] : patches are identical
> [####] : number of functional differences between upstream/downstream patch
> [down] : patch is downstream-only
> The flags [FC] indicate (F)unctional and (C)ontextual differences, respectively
> 
> 001/10:[----] [-C] 'block: Hide HBitmap in block dirty bitmap interface'
> 002/10:[----] [--] 'HBitmap: Introduce "meta" bitmap to track bit changes'
> 003/10:[----] [--] 'tests: Add test code for meta bitmap'
> 004/10:[0004] [FC] 'block: Support meta dirty bitmap'
> 005/10:[----] [--] 'block: Add two dirty bitmap getters'
> 006/10:[----] [--] 'block: Assert that bdrv_release_dirty_bitmap succeeded'
> 007/10:[----] [--] 'hbitmap: serialization'
> 008/10:[----] [-C] 'block: BdrvDirtyBitmap serialization interface'
> 009/10:[----] [--] 'tests: Add test code for hbitmap serialization'
> 010/10:[----] [--] 'block: More operations for meta dirty bitmap'
> 
> ===
> v8: Hello, is it v8 you're looking for?
> ===

Thanks, queued for 2.8:

https://github.com/XanClic/qemu/commits/block-next

(Any volunteers for a MAINTAINERS entry regarding the bitmap code? :-))

Max


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Re: [Qemu-devel] [PATCH v8 00/10] Dirty bitmap changes for migration/persistence work

[John Snow]

On 08/03/2016 12:44 PM, Max Reitz wrote:
> On 02.08.2016 02:12, John Snow wrote:
>> Key:
>> [----] : patches are identical
>> [####] : number of functional differences between upstream/downstream patch
>> [down] : patch is downstream-only
>> The flags [FC] indicate (F)unctional and (C)ontextual differences, respectively
>>
>> 001/10:[----] [-C] 'block: Hide HBitmap in block dirty bitmap interface'
>> 002/10:[----] [--] 'HBitmap: Introduce "meta" bitmap to track bit changes'
>> 003/10:[----] [--] 'tests: Add test code for meta bitmap'
>> 004/10:[0004] [FC] 'block: Support meta dirty bitmap'
>> 005/10:[----] [--] 'block: Add two dirty bitmap getters'
>> 006/10:[----] [--] 'block: Assert that bdrv_release_dirty_bitmap succeeded'
>> 007/10:[----] [--] 'hbitmap: serialization'
>> 008/10:[----] [-C] 'block: BdrvDirtyBitmap serialization interface'
>> 009/10:[----] [--] 'tests: Add test code for hbitmap serialization'
>> 010/10:[----] [--] 'block: More operations for meta dirty bitmap'
>>
>> ===
>> v8: Hello, is it v8 you're looking for?
>> ===
>
> Thanks, queued for 2.8:
>
> https://github.com/XanClic/qemu/commits/block-next
>
> (Any volunteers for a MAINTAINERS entry regarding the bitmap code? :-))
>
> Max
>

Fam and I as co-maintainers, perhaps?

--js

Re: [Qemu-devel] [PATCH v8 00/10] Dirty bitmap changes for migration/persistence work

[Fam Zheng]

On Wed, 08/03 13:00, John Snow wrote:
> 
> 
> On 08/03/2016 12:44 PM, Max Reitz wrote:
> > On 02.08.2016 02:12, John Snow wrote:
> > > Key:
> > > [----] : patches are identical
> > > [####] : number of functional differences between upstream/downstream patch
> > > [down] : patch is downstream-only
> > > The flags [FC] indicate (F)unctional and (C)ontextual differences, respectively
> > > 
> > > 001/10:[----] [-C] 'block: Hide HBitmap in block dirty bitmap interface'
> > > 002/10:[----] [--] 'HBitmap: Introduce "meta" bitmap to track bit changes'
> > > 003/10:[----] [--] 'tests: Add test code for meta bitmap'
> > > 004/10:[0004] [FC] 'block: Support meta dirty bitmap'
> > > 005/10:[----] [--] 'block: Add two dirty bitmap getters'
> > > 006/10:[----] [--] 'block: Assert that bdrv_release_dirty_bitmap succeeded'
> > > 007/10:[----] [--] 'hbitmap: serialization'
> > > 008/10:[----] [-C] 'block: BdrvDirtyBitmap serialization interface'
> > > 009/10:[----] [--] 'tests: Add test code for hbitmap serialization'
> > > 010/10:[----] [--] 'block: More operations for meta dirty bitmap'
> > > 
> > > ===
> > > v8: Hello, is it v8 you're looking for?
> > > ===
> > 
> > Thanks, queued for 2.8:
> > 
> > https://github.com/XanClic/qemu/commits/block-next
> > 
> > (Any volunteers for a MAINTAINERS entry regarding the bitmap code? :-))
> > 
> > Max
> > 
> 
> Fam and I as co-maintainers, perhaps?

Sounds good to me, feel free to send a patch, John.

Fam

Re: [Qemu-devel] [PATCH v8 07/10] hbitmap: serialization

[Max Reitz]

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On 02.08.2016 02:12, John Snow wrote:
> From: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
> 
> Functions to serialize / deserialize(restore) HBitmap. HBitmap should be
> saved to linear sequence of bits independently of endianness and bitmap
> array element (unsigned long) size. Therefore Little Endian is chosen.
> 
> These functions are appropriate for dirty bitmap migration, restoring
> the bitmap in several steps is available. To save performance, every
> step writes only the last level of the bitmap. All other levels are
> restored by hbitmap_deserialize_finish() as a last step of restoring.
> So, HBitmap is inconsistent while restoring.
> 
> Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
> [Fix left shift operand to 1UL; add "finish" parameter. - Fam]
> Signed-off-by: Fam Zheng <famz@redhat.com>
> Reviewed-by: Max Reitz <mreitz@redhat.com>
> 
> Signed-off-by: John Snow <jsnow@redhat.com>
> ---
>  include/qemu/hbitmap.h |  79 ++++++++++++++++++++++++++++
>  util/hbitmap.c         | 137 +++++++++++++++++++++++++++++++++++++++++++++++++
>  2 files changed, 216 insertions(+)
> 

[...]

> diff --git a/util/hbitmap.c b/util/hbitmap.c
> index f303975..6a13c12 100644
> --- a/util/hbitmap.c
> +++ b/util/hbitmap.c
> @@ -397,6 +397,143 @@ bool hbitmap_get(const HBitmap *hb, uint64_t item)
>      return (hb->levels[HBITMAP_LEVELS - 1][pos >> BITS_PER_LEVEL] & bit) != 0;
>  }
>  
> +uint64_t hbitmap_serialization_granularity(const HBitmap *hb)
> +{
> +    /* Require at least 64 bit granularity to be safe on both 64 bit and 32 bit
> +     * hosts. */
> +    return 64 << hb->granularity;
> +}
> +
> +/* Start should be aligned to serialization granularity, chunk size should be
> + * aligned to serialization granularity too, except for last chunk.
> + */
> +static void serialization_chunk(const HBitmap *hb,
> +                                uint64_t start, uint64_t count,
> +                                unsigned long **first_el, size_t *el_count)

As spotted by both Peter and the automatic build system, the last
parameter should be a uint64_t *.

Also, there's the issue Peter spotted on a BE machine:

http://lists.nongnu.org/archive/html/qemu-block/2016-09/msg00261.html

Because the latter is probably not as trivially fixable as the former, I
guess I'll have to drop this series from my queue for now.

Max

> +{
> +    uint64_t last = start + count - 1;
> +    uint64_t gran = hbitmap_serialization_granularity(hb);
> +
> +    assert((start & (gran - 1)) == 0);
> +    assert((last >> hb->granularity) < hb->size);
> +    if ((last >> hb->granularity) != hb->size - 1) {
> +        assert((count & (gran - 1)) == 0);
> +    }
> +
> +    start = (start >> hb->granularity) >> BITS_PER_LEVEL;
> +    last = (last >> hb->granularity) >> BITS_PER_LEVEL;
> +
> +    *first_el = &hb->levels[HBITMAP_LEVELS - 1][start];
> +    *el_count = last - start + 1;
> +}
> +


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