Blame SOURCES/kvm-qcow2-Add-refcount-update-reason-to-all-callers.patch

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From 2e86e4a584cd9054a99d6bb8d3d4d7e8878bff4a Mon Sep 17 00:00:00 2001
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From: Kevin Wolf <kwolf@redhat.com>
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Date: Mon, 9 Sep 2013 14:28:00 +0200
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Subject: [PATCH 09/38] qcow2: Add refcount update reason to all callers
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RH-Author: Kevin Wolf <kwolf@redhat.com>
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Message-id: <1378736903-18489-10-git-send-email-kwolf@redhat.com>
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Patchwork-id: 54198
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O-Subject: [RHEL-7.0 qemu-kvm PATCH 09/32] qcow2: Add refcount update reason to all callers
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Bugzilla: 1005818
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RH-Acked-by: Fam Zheng <famz@redhat.com>
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RH-Acked-by: Max Reitz <mreitz@redhat.com>
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RH-Acked-by: Miroslav Rezanina <mrezanin@redhat.com>
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Bugzilla: 1005818
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This adds a refcount update reason to all callers of update_refcounts(),
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so that a follow-up patch can use this information to decide whether
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clusters that reach a refcount of 0 should be discarded in the image
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file.
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Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
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(cherry picked from commit 6cfcb9b8b91d303ab51b78623f2299b5288d2d51)
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Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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---
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 block/qcow2-cluster.c  | 19 +++++++++++------
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 block/qcow2-refcount.c | 55 +++++++++++++++++++++++++++++++-------------------
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 block/qcow2-snapshot.c |  6 ++++--
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 block/qcow2.c          |  3 ++-
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 block/qcow2.h          | 16 ++++++++++++---
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 5 files changed, 66 insertions(+), 33 deletions(-)
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Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
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---
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 block/qcow2-cluster.c  |   19 +++++++++++-----
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 block/qcow2-refcount.c |   55 +++++++++++++++++++++++++++++------------------
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 block/qcow2-snapshot.c |    6 +++-
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 block/qcow2.c          |    3 +-
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 block/qcow2.h          |   16 +++++++++++--
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 5 files changed, 66 insertions(+), 33 deletions(-)
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diff --git a/block/qcow2-cluster.c b/block/qcow2-cluster.c
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index 76f30e5..3191d6b 100644
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--- a/block/qcow2-cluster.c
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+++ b/block/qcow2-cluster.c
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@@ -98,14 +98,16 @@ int qcow2_grow_l1_table(BlockDriverState *bs, uint64_t min_size,
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         goto fail;
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     }
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     g_free(s->l1_table);
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-    qcow2_free_clusters(bs, s->l1_table_offset, s->l1_size * sizeof(uint64_t));
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+    qcow2_free_clusters(bs, s->l1_table_offset, s->l1_size * sizeof(uint64_t),
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+                        QCOW2_DISCARD_OTHER);
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     s->l1_table_offset = new_l1_table_offset;
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     s->l1_table = new_l1_table;
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     s->l1_size = new_l1_size;
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     return 0;
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  fail:
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     g_free(new_l1_table);
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-    qcow2_free_clusters(bs, new_l1_table_offset, new_l1_size2);
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+    qcow2_free_clusters(bs, new_l1_table_offset, new_l1_size2,
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+                        QCOW2_DISCARD_OTHER);
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     return ret;
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 }
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@@ -548,7 +550,8 @@ static int get_cluster_table(BlockDriverState *bs, uint64_t offset,
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         /* Then decrease the refcount of the old table */
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         if (l2_offset) {
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-            qcow2_free_clusters(bs, l2_offset, s->l2_size * sizeof(uint64_t));
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+            qcow2_free_clusters(bs, l2_offset, s->l2_size * sizeof(uint64_t),
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+                                QCOW2_DISCARD_OTHER);
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         }
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     }
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@@ -715,10 +718,14 @@ int qcow2_alloc_cluster_link_l2(BlockDriverState *bs, QCowL2Meta *m)
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     /*
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      * If this was a COW, we need to decrease the refcount of the old cluster.
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      * Also flush bs->file to get the right order for L2 and refcount update.
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+     *
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+     * Don't discard clusters that reach a refcount of 0 (e.g. compressed
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+     * clusters), the next write will reuse them anyway.
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      */
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     if (j != 0) {
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         for (i = 0; i < j; i++) {
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-            qcow2_free_any_clusters(bs, be64_to_cpu(old_cluster[i]), 1);
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+            qcow2_free_any_clusters(bs, be64_to_cpu(old_cluster[i]), 1,
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+                                    QCOW2_DISCARD_NEVER);
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         }
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     }
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@@ -1339,7 +1346,7 @@ static int discard_single_l2(BlockDriverState *bs, uint64_t offset,
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         l2_table[l2_index + i] = cpu_to_be64(0);
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         /* Then decrease the refcount */
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-        qcow2_free_any_clusters(bs, old_offset, 1);
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+        qcow2_free_any_clusters(bs, old_offset, 1, QCOW2_DISCARD_REQUEST);
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     }
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     ret = qcow2_cache_put(bs, s->l2_table_cache, (void**) &l2_table);
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@@ -1415,7 +1422,7 @@ static int zero_single_l2(BlockDriverState *bs, uint64_t offset,
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         qcow2_cache_entry_mark_dirty(s->l2_table_cache, l2_table);
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         if (old_offset & QCOW_OFLAG_COMPRESSED) {
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             l2_table[l2_index + i] = cpu_to_be64(QCOW_OFLAG_ZERO);
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-            qcow2_free_any_clusters(bs, old_offset, 1);
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+            qcow2_free_any_clusters(bs, old_offset, 1, QCOW2_DISCARD_REQUEST);
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         } else {
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             l2_table[l2_index + i] |= cpu_to_be64(QCOW_OFLAG_ZERO);
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         }
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diff --git a/block/qcow2-refcount.c b/block/qcow2-refcount.c
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index b32738f..6d35e49 100644
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--- a/block/qcow2-refcount.c
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+++ b/block/qcow2-refcount.c
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@@ -29,7 +29,7 @@
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 static int64_t alloc_clusters_noref(BlockDriverState *bs, int64_t size);
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 static int QEMU_WARN_UNUSED_RESULT update_refcount(BlockDriverState *bs,
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                             int64_t offset, int64_t length,
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-                            int addend);
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+                            int addend, enum qcow2_discard_type type);
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 /*********************************************************/
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@@ -235,7 +235,8 @@ static int alloc_refcount_block(BlockDriverState *bs,
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     } else {
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         /* Described somewhere else. This can recurse at most twice before we
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          * arrive at a block that describes itself. */
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-        ret = update_refcount(bs, new_block, s->cluster_size, 1);
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+        ret = update_refcount(bs, new_block, s->cluster_size, 1,
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+                              QCOW2_DISCARD_NEVER);
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         if (ret < 0) {
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             goto fail_block;
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         }
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@@ -399,7 +400,8 @@ static int alloc_refcount_block(BlockDriverState *bs,
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     /* Free old table. Remember, we must not change free_cluster_index */
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     uint64_t old_free_cluster_index = s->free_cluster_index;
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-    qcow2_free_clusters(bs, old_table_offset, old_table_size * sizeof(uint64_t));
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+    qcow2_free_clusters(bs, old_table_offset, old_table_size * sizeof(uint64_t),
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+                        QCOW2_DISCARD_OTHER);
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     s->free_cluster_index = old_free_cluster_index;
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     ret = load_refcount_block(bs, new_block, (void**) refcount_block);
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@@ -420,7 +422,7 @@ fail_block:
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 /* XXX: cache several refcount block clusters ? */
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 static int QEMU_WARN_UNUSED_RESULT update_refcount(BlockDriverState *bs,
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-    int64_t offset, int64_t length, int addend)
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+    int64_t offset, int64_t length, int addend, enum qcow2_discard_type type)
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 {
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     BDRVQcowState *s = bs->opaque;
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     int64_t start, last, cluster_offset;
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@@ -506,7 +508,8 @@ fail:
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      */
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     if (ret < 0) {
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         int dummy;
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-        dummy = update_refcount(bs, offset, cluster_offset - offset, -addend);
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+        dummy = update_refcount(bs, offset, cluster_offset - offset, -addend,
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+                                QCOW2_DISCARD_NEVER);
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         (void)dummy;
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     }
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@@ -522,12 +525,14 @@ fail:
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  */
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 static int update_cluster_refcount(BlockDriverState *bs,
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                                    int64_t cluster_index,
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-                                   int addend)
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+                                   int addend,
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+                                   enum qcow2_discard_type type)
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 {
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     BDRVQcowState *s = bs->opaque;
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     int ret;
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-    ret = update_refcount(bs, cluster_index << s->cluster_bits, 1, addend);
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+    ret = update_refcount(bs, cluster_index << s->cluster_bits, 1, addend,
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+                          type);
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     if (ret < 0) {
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         return ret;
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     }
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@@ -579,7 +584,7 @@ int64_t qcow2_alloc_clusters(BlockDriverState *bs, int64_t size)
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         return offset;
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     }
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-    ret = update_refcount(bs, offset, size, 1);
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+    ret = update_refcount(bs, offset, size, 1, QCOW2_DISCARD_NEVER);
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     if (ret < 0) {
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         return ret;
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     }
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@@ -611,7 +616,8 @@ int qcow2_alloc_clusters_at(BlockDriverState *bs, uint64_t offset,
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     old_free_cluster_index = s->free_cluster_index;
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     s->free_cluster_index = cluster_index + i;
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-    ret = update_refcount(bs, offset, i << s->cluster_bits, 1);
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+    ret = update_refcount(bs, offset, i << s->cluster_bits, 1,
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+                          QCOW2_DISCARD_NEVER);
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     if (ret < 0) {
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         return ret;
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     }
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@@ -649,7 +655,8 @@ int64_t qcow2_alloc_bytes(BlockDriverState *bs, int size)
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         if (free_in_cluster == 0)
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             s->free_byte_offset = 0;
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         if ((offset & (s->cluster_size - 1)) != 0)
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-            update_cluster_refcount(bs, offset >> s->cluster_bits, 1);
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+            update_cluster_refcount(bs, offset >> s->cluster_bits, 1,
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+                                    QCOW2_DISCARD_NEVER);
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     } else {
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         offset = qcow2_alloc_clusters(bs, s->cluster_size);
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         if (offset < 0) {
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@@ -659,7 +666,8 @@ int64_t qcow2_alloc_bytes(BlockDriverState *bs, int size)
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         if ((cluster_offset + s->cluster_size) == offset) {
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             /* we are lucky: contiguous data */
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             offset = s->free_byte_offset;
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-            update_cluster_refcount(bs, offset >> s->cluster_bits, 1);
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+            update_cluster_refcount(bs, offset >> s->cluster_bits, 1,
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+                                    QCOW2_DISCARD_NEVER);
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             s->free_byte_offset += size;
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         } else {
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             s->free_byte_offset = offset;
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@@ -676,12 +684,13 @@ int64_t qcow2_alloc_bytes(BlockDriverState *bs, int size)
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 }
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 void qcow2_free_clusters(BlockDriverState *bs,
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-                          int64_t offset, int64_t size)
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+                          int64_t offset, int64_t size,
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+                          enum qcow2_discard_type type)
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 {
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     int ret;
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     BLKDBG_EVENT(bs->file, BLKDBG_CLUSTER_FREE);
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-    ret = update_refcount(bs, offset, size, -1);
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+    ret = update_refcount(bs, offset, size, -1, type);
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     if (ret < 0) {
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         fprintf(stderr, "qcow2_free_clusters failed: %s\n", strerror(-ret));
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         /* TODO Remember the clusters to free them later and avoid leaking */
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@@ -692,8 +701,8 @@ void qcow2_free_clusters(BlockDriverState *bs,
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  * Free a cluster using its L2 entry (handles clusters of all types, e.g.
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  * normal cluster, compressed cluster, etc.)
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  */
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-void qcow2_free_any_clusters(BlockDriverState *bs,
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-    uint64_t l2_entry, int nb_clusters)
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+void qcow2_free_any_clusters(BlockDriverState *bs, uint64_t l2_entry,
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+                             int nb_clusters, enum qcow2_discard_type type)
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 {
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     BDRVQcowState *s = bs->opaque;
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@@ -705,12 +714,12 @@ void qcow2_free_any_clusters(BlockDriverState *bs,
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                            s->csize_mask) + 1;
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             qcow2_free_clusters(bs,
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                 (l2_entry & s->cluster_offset_mask) & ~511,
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-                nb_csectors * 512);
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+                nb_csectors * 512, type);
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         }
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         break;
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     case QCOW2_CLUSTER_NORMAL:
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         qcow2_free_clusters(bs, l2_entry & L2E_OFFSET_MASK,
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-                            nb_clusters << s->cluster_bits);
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+                            nb_clusters << s->cluster_bits, type);
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         break;
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     case QCOW2_CLUSTER_UNALLOCATED:
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     case QCOW2_CLUSTER_ZERO:
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@@ -785,7 +794,8 @@ int qcow2_update_snapshot_refcount(BlockDriverState *bs,
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                             int ret;
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                             ret = update_refcount(bs,
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                                 (offset & s->cluster_offset_mask) & ~511,
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-                                nb_csectors * 512, addend);
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+                                nb_csectors * 512, addend,
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+                                QCOW2_DISCARD_SNAPSHOT);
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                             if (ret < 0) {
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                                 goto fail;
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                             }
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@@ -795,7 +805,8 @@ int qcow2_update_snapshot_refcount(BlockDriverState *bs,
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                     } else {
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                         uint64_t cluster_index = (offset & L2E_OFFSET_MASK) >> s->cluster_bits;
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                         if (addend != 0) {
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-                            refcount = update_cluster_refcount(bs, cluster_index, addend);
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+                            refcount = update_cluster_refcount(bs, cluster_index, addend,
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+                                                               QCOW2_DISCARD_SNAPSHOT);
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                         } else {
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                             refcount = get_refcount(bs, cluster_index);
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                         }
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@@ -827,7 +838,8 @@ int qcow2_update_snapshot_refcount(BlockDriverState *bs,
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             if (addend != 0) {
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-                refcount = update_cluster_refcount(bs, l2_offset >> s->cluster_bits, addend);
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+                refcount = update_cluster_refcount(bs, l2_offset >> s->cluster_bits, addend,
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+                                                   QCOW2_DISCARD_SNAPSHOT);
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             } else {
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                 refcount = get_refcount(bs, l2_offset >> s->cluster_bits);
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             }
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@@ -1253,7 +1265,8 @@ int qcow2_check_refcounts(BlockDriverState *bs, BdrvCheckResult *res,
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             if (num_fixed) {
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                 ret = update_refcount(bs, i << s->cluster_bits, 1,
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-                                      refcount2 - refcount1);
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+                                      refcount2 - refcount1,
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+                                      QCOW2_DISCARD_ALWAYS);
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                 if (ret >= 0) {
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                     (*num_fixed)++;
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                     continue;
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diff --git a/block/qcow2-snapshot.c b/block/qcow2-snapshot.c
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index 992a5c8..0caac90 100644
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--- a/block/qcow2-snapshot.c
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+++ b/block/qcow2-snapshot.c
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@@ -262,7 +262,8 @@ static int qcow2_write_snapshots(BlockDriverState *bs)
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     }
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     /* free the old snapshot table */
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-    qcow2_free_clusters(bs, s->snapshots_offset, s->snapshots_size);
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+    qcow2_free_clusters(bs, s->snapshots_offset, s->snapshots_size,
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+                        QCOW2_DISCARD_SNAPSHOT);
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     s->snapshots_offset = snapshots_offset;
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     s->snapshots_size = snapshots_size;
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     return 0;
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@@ -569,7 +570,8 @@ int qcow2_snapshot_delete(BlockDriverState *bs, const char *snapshot_id)
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     if (ret < 0) {
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         return ret;
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     }
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-    qcow2_free_clusters(bs, sn.l1_table_offset, sn.l1_size * sizeof(uint64_t));
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+    qcow2_free_clusters(bs, sn.l1_table_offset, sn.l1_size * sizeof(uint64_t),
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+                        QCOW2_DISCARD_SNAPSHOT);
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     /* must update the copied flag on the current cluster offsets */
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     ret = qcow2_update_snapshot_refcount(bs, s->l1_table_offset, s->l1_size, 0);
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diff --git a/block/qcow2.c b/block/qcow2.c
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index 0fa5cb2..e28ea47 100644
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--- a/block/qcow2.c
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+++ b/block/qcow2.c
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@@ -1196,7 +1196,8 @@ static int preallocate(BlockDriverState *bs)
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         ret = qcow2_alloc_cluster_link_l2(bs, meta);
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         if (ret < 0) {
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-            qcow2_free_any_clusters(bs, meta->alloc_offset, meta->nb_clusters);
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+            qcow2_free_any_clusters(bs, meta->alloc_offset, meta->nb_clusters,
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+                                    QCOW2_DISCARD_NEVER);
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             return ret;
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         }
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diff --git a/block/qcow2.h b/block/qcow2.h
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index 6959c6a..64a6479 100644
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--- a/block/qcow2.h
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+++ b/block/qcow2.h
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@@ -129,6 +129,15 @@ enum {
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     QCOW2_COMPAT_FEAT_MASK            = QCOW2_COMPAT_LAZY_REFCOUNTS,
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 };
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+enum qcow2_discard_type {
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+    QCOW2_DISCARD_NEVER = 0,
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+    QCOW2_DISCARD_ALWAYS,
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+    QCOW2_DISCARD_REQUEST,
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+    QCOW2_DISCARD_SNAPSHOT,
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+    QCOW2_DISCARD_OTHER,
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+    QCOW2_DISCARD_MAX
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+};
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+
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 typedef struct Qcow2Feature {
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     uint8_t type;
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     uint8_t bit;
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@@ -349,9 +358,10 @@ int qcow2_alloc_clusters_at(BlockDriverState *bs, uint64_t offset,
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     int nb_clusters);
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 int64_t qcow2_alloc_bytes(BlockDriverState *bs, int size);
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 void qcow2_free_clusters(BlockDriverState *bs,
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-    int64_t offset, int64_t size);
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-void qcow2_free_any_clusters(BlockDriverState *bs,
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-    uint64_t cluster_offset, int nb_clusters);
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+                          int64_t offset, int64_t size,
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+                          enum qcow2_discard_type type);
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+void qcow2_free_any_clusters(BlockDriverState *bs, uint64_t l2_entry,
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+                             int nb_clusters, enum qcow2_discard_type type);
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 int qcow2_update_snapshot_refcount(BlockDriverState *bs,
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     int64_t l1_table_offset, int l1_size, int addend);
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-- 
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1.7.1
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