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From 7f0500dff4d7da11bda309de3866851f382f6fe8 Mon Sep 17 00:00:00 2001
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From: Max Reitz <mreitz@redhat.com>
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Date: Mon, 4 Nov 2013 22:32:03 +0100
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Subject: [PATCH 10/87] qcow2-refcount: Repair OFLAG_COPIED errors
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RH-Author: Max Reitz <mreitz@redhat.com>
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Message-id: <1383604354-12743-13-git-send-email-mreitz@redhat.com>
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Patchwork-id: 55312
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O-Subject: [RHEL-7.0 qemu-kvm PATCH 12/43] qcow2-refcount: Repair OFLAG_COPIED errors
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Bugzilla: 1004347
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RH-Acked-by: Kevin Wolf <kwolf@redhat.com>
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RH-Acked-by: Laszlo Ersek <lersek@redhat.com>
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RH-Acked-by: Fam Zheng <famz@redhat.com>
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RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
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BZ: 1004347
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Since the OFLAG_COPIED checks are now executed after the refcounts have
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been repaired (if repairing), it is safe to assume that they are correct
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but the OFLAG_COPIED flag may be not. Therefore, if its value differs
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from what it should be (considering the according refcount), that
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discrepancy can be repaired by correctly setting (or clearing that flag.
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Signed-off-by: Max Reitz <mreitz@redhat.com>
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Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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(cherry picked from commit e23e400ec62a03dea58ddb38479b4f1ef86f556d)
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Signed-off-by: Max Reitz <mreitz@redhat.com>
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---
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 block/qcow2-cluster.c  |  4 ++--
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 block/qcow2-refcount.c | 58 ++++++++++++++++++++++++++++++++++++++++++++------
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 block/qcow2.h          |  1 +
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 3 files changed, 55 insertions(+), 8 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  |    4 +-
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 block/qcow2-refcount.c |   58 +++++++++++++++++++++++++++++++++++++++++++-----
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 block/qcow2.h          |    1 +
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 3 files changed, 55 insertions(+), 8 deletions(-)
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diff --git a/block/qcow2-cluster.c b/block/qcow2-cluster.c
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index 7c248aa..2d5aa92 100644
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--- a/block/qcow2-cluster.c
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+++ b/block/qcow2-cluster.c
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@@ -145,7 +145,7 @@ static int l2_load(BlockDriverState *bs, uint64_t l2_offset,
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  * and we really don't want bdrv_pread to perform a read-modify-write)
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  */
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 #define L1_ENTRIES_PER_SECTOR (512 / 8)
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-static int write_l1_entry(BlockDriverState *bs, int l1_index)
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+int qcow2_write_l1_entry(BlockDriverState *bs, int l1_index)
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 {
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     BDRVQcowState *s = bs->opaque;
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     uint64_t buf[L1_ENTRIES_PER_SECTOR];
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@@ -254,7 +254,7 @@ static int l2_allocate(BlockDriverState *bs, int l1_index, uint64_t **table)
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     /* update the L1 entry */
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     trace_qcow2_l2_allocate_write_l1(bs, l1_index);
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     s->l1_table[l1_index] = l2_offset | QCOW_OFLAG_COPIED;
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-    ret = write_l1_entry(bs, l1_index);
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+    ret = qcow2_write_l1_entry(bs, l1_index);
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     if (ret < 0) {
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         goto fail;
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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 ddc3029..92ecc64 100644
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--- a/block/qcow2-refcount.c
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+++ b/block/qcow2-refcount.c
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@@ -1207,7 +1207,8 @@ fail:
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  * been already detected and sufficiently signaled by the calling function
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  * (qcow2_check_refcounts) by the time this function is called).
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  */
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-static int check_oflag_copied(BlockDriverState *bs, BdrvCheckResult *res)
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+static int check_oflag_copied(BlockDriverState *bs, BdrvCheckResult *res,
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+                              BdrvCheckMode fix)
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 {
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     BDRVQcowState *s = bs->opaque;
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     uint64_t *l2_table = qemu_blockalign(bs, s->cluster_size);
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@@ -1218,6 +1219,7 @@ static int check_oflag_copied(BlockDriverState *bs, BdrvCheckResult *res)
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     for (i = 0; i < s->l1_size; i++) {
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         uint64_t l1_entry = s->l1_table[i];
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         uint64_t l2_offset = l1_entry & L1E_OFFSET_MASK;
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+        bool l2_dirty = false;
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         if (!l2_offset) {
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             continue;
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@@ -1229,10 +1231,24 @@ static int check_oflag_copied(BlockDriverState *bs, BdrvCheckResult *res)
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             continue;
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         }
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         if ((refcount == 1) != ((l1_entry & QCOW_OFLAG_COPIED) != 0)) {
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-            fprintf(stderr, "ERROR OFLAG_COPIED L2 cluster: l1_index=%d "
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+            fprintf(stderr, "%s OFLAG_COPIED L2 cluster: l1_index=%d "
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                     "l1_entry=%" PRIx64 " refcount=%d\n",
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+                    fix & BDRV_FIX_ERRORS ? "Repairing" :
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+                                            "ERROR",
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                     i, l1_entry, refcount);
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-            res->corruptions++;
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+            if (fix & BDRV_FIX_ERRORS) {
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+                s->l1_table[i] = refcount == 1
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+                               ? l1_entry |  QCOW_OFLAG_COPIED
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+                               : l1_entry & ~QCOW_OFLAG_COPIED;
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+                ret = qcow2_write_l1_entry(bs, i);
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+                if (ret < 0) {
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+                    res->check_errors++;
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+                    goto fail;
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+                }
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+                res->corruptions_fixed++;
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+            } else {
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+                res->corruptions++;
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+            }
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         }
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         ret = bdrv_pread(bs->file, l2_offset, l2_table,
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@@ -1257,13 +1273,43 @@ static int check_oflag_copied(BlockDriverState *bs, BdrvCheckResult *res)
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                     continue;
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                 }
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                 if ((refcount == 1) != ((l2_entry & QCOW_OFLAG_COPIED) != 0)) {
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-                    fprintf(stderr, "ERROR OFLAG_COPIED data cluster: "
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+                    fprintf(stderr, "%s OFLAG_COPIED data cluster: "
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                             "l2_entry=%" PRIx64 " refcount=%d\n",
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+                            fix & BDRV_FIX_ERRORS ? "Repairing" :
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+                                                    "ERROR",
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                             l2_entry, refcount);
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-                    res->corruptions++;
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+                    if (fix & BDRV_FIX_ERRORS) {
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+                        l2_table[j] = cpu_to_be64(refcount == 1
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+                                    ? l2_entry |  QCOW_OFLAG_COPIED
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+                                    : l2_entry & ~QCOW_OFLAG_COPIED);
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+                        l2_dirty = true;
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+                        res->corruptions_fixed++;
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+                    } else {
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+                        res->corruptions++;
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+                    }
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                 }
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             }
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         }
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+
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+        if (l2_dirty) {
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+            ret = qcow2_pre_write_overlap_check(bs,
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+                    QCOW2_OL_DEFAULT & ~QCOW2_OL_ACTIVE_L2, l2_offset,
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+                    s->cluster_size);
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+            if (ret < 0) {
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+                fprintf(stderr, "ERROR: Could not write L2 table; metadata "
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+                        "overlap check failed: %s\n", strerror(-ret));
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+                res->check_errors++;
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+                goto fail;
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+            }
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+
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+            ret = bdrv_pwrite(bs->file, l2_offset, l2_table, s->cluster_size);
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+            if (ret < 0) {
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+                fprintf(stderr, "ERROR: Could not write L2 table: %s\n",
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+                        strerror(-ret));
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+                res->check_errors++;
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+                goto fail;
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+            }
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+        }
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     }
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     ret = 0;
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@@ -1409,7 +1455,7 @@ int qcow2_check_refcounts(BlockDriverState *bs, BdrvCheckResult *res,
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     }
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     /* check OFLAG_COPIED */
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-    ret = check_oflag_copied(bs, res);
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+    ret = check_oflag_copied(bs, res, fix);
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     if (ret < 0) {
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         goto fail;
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     }
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diff --git a/block/qcow2.h b/block/qcow2.h
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index 86ddb30..10b7bf4 100644
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--- a/block/qcow2.h
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+++ b/block/qcow2.h
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@@ -432,6 +432,7 @@ int qcow2_pre_write_overlap_check(BlockDriverState *bs, int chk, int64_t offset,
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 /* qcow2-cluster.c functions */
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 int qcow2_grow_l1_table(BlockDriverState *bs, uint64_t min_size,
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                         bool exact_size);
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+int qcow2_write_l1_entry(BlockDriverState *bs, int l1_index);
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 void qcow2_l2_cache_reset(BlockDriverState *bs);
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 int qcow2_decompress_cluster(BlockDriverState *bs, uint64_t cluster_offset);
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 void qcow2_encrypt_sectors(BDRVQcowState *s, int64_t sector_num,
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-- 
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1.7.1
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