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Blame SOURCES/kvm-dirty-bitmap-make-it-possible-to-restore-bitmap-afte.patch

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From 4122c0993f5b6de8db0227f5751e1f49e0b4354c Mon Sep 17 00:00:00 2001
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From: John Snow <jsnow@redhat.com>
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Date: Tue, 20 Nov 2018 18:18:13 +0000
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Subject: [PATCH 19/35] dirty-bitmap: make it possible to restore bitmap after
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 merge
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RH-Author: John Snow <jsnow@redhat.com>
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Message-id: <20181120181828.15132-10-jsnow@redhat.com>
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Patchwork-id: 83057
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O-Subject: [RHEL8/rhel qemu-kvm PATCH 09/24] dirty-bitmap: make it possible to restore bitmap after merge
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Bugzilla: 1518989
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RH-Acked-by: Laurent Vivier <lvivier@redhat.com>
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RH-Acked-by: Max Reitz <mreitz@redhat.com>
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RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
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From: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
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Add backup parameter to bdrv_merge_dirty_bitmap() to be used then with
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bdrv_restore_dirty_bitmap() if it needed to restore the bitmap after
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merge operation.
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This is needed to implement bitmap merge transaction action in further
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commit.
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Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
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Reviewed-by: John Snow <jsnow@redhat.com>
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(cherry picked from commit fa000f2f9fd96a75a0a33d50ead247fce11da92a)
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Signed-off-by: John Snow <jsnow@redhat.com>
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Signed-off-by: Danilo C. L. de Paula <ddepaula@redhat.com>
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---
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 block/dirty-bitmap.c         | 17 ++++++++++++++---
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 blockdev.c                   |  2 +-
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 include/block/dirty-bitmap.h |  2 +-
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 include/qemu/hbitmap.h       | 25 ++++++++++++++++---------
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 util/hbitmap.c               | 11 ++++++++---
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 5 files changed, 40 insertions(+), 17 deletions(-)
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diff --git a/block/dirty-bitmap.c b/block/dirty-bitmap.c
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index 017ee9d..8ac933c 100644
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--- a/block/dirty-bitmap.c
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+++ b/block/dirty-bitmap.c
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@@ -314,7 +314,7 @@ BdrvDirtyBitmap *bdrv_reclaim_dirty_bitmap_locked(BlockDriverState *bs,
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         return NULL;
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     }
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-    if (!hbitmap_merge(parent->bitmap, successor->bitmap)) {
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+    if (!hbitmap_merge(parent->bitmap, successor->bitmap, parent->bitmap)) {
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         error_setg(errp, "Merging of parent and successor bitmap failed");
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         return NULL;
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     }
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@@ -791,8 +791,10 @@ int64_t bdrv_dirty_bitmap_next_zero(BdrvDirtyBitmap *bitmap, uint64_t offset)
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 }
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 void bdrv_merge_dirty_bitmap(BdrvDirtyBitmap *dest, const BdrvDirtyBitmap *src,
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-                             Error **errp)
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+                             HBitmap **backup, Error **errp)
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 {
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+    bool ret;
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+
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     /* only bitmaps from one bds are supported */
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     assert(dest->mutex == src->mutex);
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@@ -810,11 +812,20 @@ void bdrv_merge_dirty_bitmap(BdrvDirtyBitmap *dest, const BdrvDirtyBitmap *src,
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         goto out;
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     }
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-    if (!hbitmap_merge(dest->bitmap, src->bitmap)) {
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+    if (!hbitmap_can_merge(dest->bitmap, src->bitmap)) {
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         error_setg(errp, "Bitmaps are incompatible and can't be merged");
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         goto out;
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     }
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+    if (backup) {
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+        *backup = dest->bitmap;
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+        dest->bitmap = hbitmap_alloc(dest->size, hbitmap_granularity(*backup));
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+        ret = hbitmap_merge(*backup, src->bitmap, dest->bitmap);
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+    } else {
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+        ret = hbitmap_merge(dest->bitmap, src->bitmap, dest->bitmap);
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+    }
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+    assert(ret);
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+
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 out:
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     qemu_mutex_unlock(dest->mutex);
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 }
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diff --git a/blockdev.c b/blockdev.c
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index 2d86465..a10fbbd 100644
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--- a/blockdev.c
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+++ b/blockdev.c
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@@ -3077,7 +3077,7 @@ void qmp_x_block_dirty_bitmap_merge(const char *node, const char *dst_name,
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         return;
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     }
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-    bdrv_merge_dirty_bitmap(dst, src, errp);
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+    bdrv_merge_dirty_bitmap(dst, src, NULL, errp);
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 }
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 BlockDirtyBitmapSha256 *qmp_x_debug_block_dirty_bitmap_sha256(const char *node,
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diff --git a/include/block/dirty-bitmap.h b/include/block/dirty-bitmap.h
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index 259bd27..201ff7f 100644
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--- a/include/block/dirty-bitmap.h
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+++ b/include/block/dirty-bitmap.h
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@@ -71,7 +71,7 @@ void bdrv_dirty_bitmap_set_persistance(BdrvDirtyBitmap *bitmap,
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                                        bool persistent);
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 void bdrv_dirty_bitmap_set_qmp_locked(BdrvDirtyBitmap *bitmap, bool qmp_locked);
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 void bdrv_merge_dirty_bitmap(BdrvDirtyBitmap *dest, const BdrvDirtyBitmap *src,
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-                             Error **errp);
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+                             HBitmap **backup, Error **errp);
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 /* Functions that require manual locking.  */
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 void bdrv_dirty_bitmap_lock(BdrvDirtyBitmap *bitmap);
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diff --git a/include/qemu/hbitmap.h b/include/qemu/hbitmap.h
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index ddca52c..a7cb780 100644
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--- a/include/qemu/hbitmap.h
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+++ b/include/qemu/hbitmap.h
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@@ -73,16 +73,23 @@ void hbitmap_truncate(HBitmap *hb, uint64_t size);
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 /**
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  * hbitmap_merge:
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- * @a: The bitmap to store the result in.
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- * @b: The bitmap to merge into @a.
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- * @return true if the merge was successful,
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- *         false if it was not attempted.
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- *
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- * Merge two bitmaps together.
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- * A := A (BITOR) B.
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- * B is left unmodified.
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+ *
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+ * Store result of merging @a and @b into @result.
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+ * @result is allowed to be equal to @a or @b.
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+ *
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+ * Return true if the merge was successful,
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+ *        false if it was not attempted.
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+ */
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+bool hbitmap_merge(const HBitmap *a, const HBitmap *b, HBitmap *result);
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+
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+/**
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+ * hbitmap_can_merge:
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+ *
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+ * hbitmap_can_merge(a, b) && hbitmap_can_merge(a, result) is sufficient and
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+ * necessary for hbitmap_merge will not fail.
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+ *
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  */
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-bool hbitmap_merge(HBitmap *a, const HBitmap *b);
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+bool hbitmap_can_merge(const HBitmap *a, const HBitmap *b);
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 /**
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  * hbitmap_empty:
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diff --git a/util/hbitmap.c b/util/hbitmap.c
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index bcd3040..d5aca51 100644
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--- a/util/hbitmap.c
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+++ b/util/hbitmap.c
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@@ -723,6 +723,10 @@ void hbitmap_truncate(HBitmap *hb, uint64_t size)
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     }
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 }
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+bool hbitmap_can_merge(const HBitmap *a, const HBitmap *b)
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+{
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+    return (a->size == b->size) && (a->granularity == b->granularity);
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+}
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 /**
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  * Given HBitmaps A and B, let A := A (BITOR) B.
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@@ -731,14 +735,15 @@ void hbitmap_truncate(HBitmap *hb, uint64_t size)
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  * @return true if the merge was successful,
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  *         false if it was not attempted.
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  */
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-bool hbitmap_merge(HBitmap *a, const HBitmap *b)
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+bool hbitmap_merge(const HBitmap *a, const HBitmap *b, HBitmap *result)
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 {
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     int i;
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     uint64_t j;
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-    if ((a->size != b->size) || (a->granularity != b->granularity)) {
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+    if (!hbitmap_can_merge(a, b) || !hbitmap_can_merge(a, result)) {
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         return false;
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     }
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+    assert(hbitmap_can_merge(b, result));
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     if (hbitmap_count(b) == 0) {
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         return true;
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@@ -750,7 +755,7 @@ bool hbitmap_merge(HBitmap *a, const HBitmap *b)
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      */
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     for (i = HBITMAP_LEVELS - 1; i >= 0; i--) {
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         for (j = 0; j < a->sizes[i]; j++) {
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-            a->levels[i][j] |= b->levels[i][j];
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+            result->levels[i][j] = a->levels[i][j] | b->levels[i][j];
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         }
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     }
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-- 
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1.8.3.1
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