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From 68066d2b824a88a45b3263dd1ceb18307c92581f Mon Sep 17 00:00:00 2001
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From: Max Reitz <mreitz@redhat.com>
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Date: Sat, 15 Feb 2014 16:03:47 +0100
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Subject: [PATCH 2/5] qcow2: remove n_start and n_end of qcow2_alloc_cluster_offset()
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RH-Author: Max Reitz <mreitz@redhat.com>
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Message-id: <1392480230-24011-2-git-send-email-mreitz@redhat.com>
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Patchwork-id: 57292
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O-Subject: [RHEL-7.0 qemu-kvm PATCH 1/4] qcow2: remove n_start and n_end of qcow2_alloc_cluster_offset()
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Bugzilla: 1049176
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RH-Acked-by: Kevin Wolf <kwolf@redhat.com>
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RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
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RH-Acked-by: Fam Zheng <famz@redhat.com>
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From: Hu Tao <hutao@cn.fujitsu.com>
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BZ: 1049176
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BZ: 1055848
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n_start can be actually calculated from offset. The number of
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sectors to be allocated(n_end - n_start) can be passed in in
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num. By removing n_start and n_end, we can save two parameters.
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The side effect is there is a bug in qcow2.c:preallocate() that
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passes incorrect n_start to qcow2_alloc_cluster_offset() is
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fixed. The bug can be triggerred by a larger cluster size than
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the default value(65536), for example:
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./qemu-img create -f qcow2 \
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  -o 'cluster_size=131072,preallocation=metadata' file.img 4G
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Signed-off-by: Hu Tao <hutao@cn.fujitsu.com>
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Reviewed-by: Max Reitz <mreitz@redhat.com>
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Reviewed-by: Benoit Canet <benoit@irqsave.net>
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Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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(cherry picked from commit 16f0587e0a5da5b1ad76cb7c3739491bc042201c)
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Signed-off-by: Max Reitz <mreitz@redhat.com>
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---
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 block/qcow2-cluster.c | 14 ++++++--------
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 block/qcow2.c         | 13 +++++++------
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 block/qcow2.h         |  2 +-
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 trace-events          |  2 +-
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 4 files changed, 15 insertions(+), 16 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 |   14 ++++++--------
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 block/qcow2.c         |   13 +++++++------
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 block/qcow2.h         |    2 +-
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 trace-events          |    2 +-
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 4 files changed, 15 insertions(+), 16 deletions(-)
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diff --git a/block/qcow2-cluster.c b/block/qcow2-cluster.c
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index 79c3ae0..862df0f 100644
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--- a/block/qcow2-cluster.c
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+++ b/block/qcow2-cluster.c
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@@ -1173,7 +1173,7 @@ fail:
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  * Return 0 on success and -errno in error cases
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  */
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 int qcow2_alloc_cluster_offset(BlockDriverState *bs, uint64_t offset,
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-    int n_start, int n_end, int *num, uint64_t *host_offset, QCowL2Meta **m)
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+    int *num, uint64_t *host_offset, QCowL2Meta **m)
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 {
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     BDRVQcowState *s = bs->opaque;
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     uint64_t start, remaining;
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@@ -1181,15 +1181,13 @@ int qcow2_alloc_cluster_offset(BlockDriverState *bs, uint64_t offset,
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     uint64_t cur_bytes;
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     int ret;
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-    trace_qcow2_alloc_clusters_offset(qemu_coroutine_self(), offset,
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-                                      n_start, n_end);
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+    trace_qcow2_alloc_clusters_offset(qemu_coroutine_self(), offset, *num);
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-    assert(n_start * BDRV_SECTOR_SIZE == offset_into_cluster(s, offset));
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-    offset = start_of_cluster(s, offset);
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+    assert((offset & ~BDRV_SECTOR_MASK) == 0);
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 again:
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-    start = offset + (n_start << BDRV_SECTOR_BITS);
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-    remaining = (n_end - n_start) << BDRV_SECTOR_BITS;
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+    start = offset;
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+    remaining = *num << BDRV_SECTOR_BITS;
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     cluster_offset = 0;
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     *host_offset = 0;
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     cur_bytes = 0;
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@@ -1275,7 +1273,7 @@ again:
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         }
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     }
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-    *num = (n_end - n_start) - (remaining >> BDRV_SECTOR_BITS);
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+    *num -= remaining >> BDRV_SECTOR_BITS;
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     assert(*num > 0);
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     assert(*host_offset != 0);
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diff --git a/block/qcow2.c b/block/qcow2.c
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index 25a5b5e..fe950b4 100644
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--- a/block/qcow2.c
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+++ b/block/qcow2.c
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@@ -1000,7 +1000,6 @@ static coroutine_fn int qcow2_co_writev(BlockDriverState *bs,
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 {
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     BDRVQcowState *s = bs->opaque;
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     int index_in_cluster;
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-    int n_end;
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     int ret;
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     int cur_nr_sectors; /* number of sectors in current iteration */
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     uint64_t cluster_offset;
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@@ -1024,14 +1023,16 @@ static coroutine_fn int qcow2_co_writev(BlockDriverState *bs,
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         trace_qcow2_writev_start_part(qemu_coroutine_self());
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         index_in_cluster = sector_num & (s->cluster_sectors - 1);
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-        n_end = index_in_cluster + remaining_sectors;
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+        cur_nr_sectors = remaining_sectors;
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         if (s->crypt_method &&
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-            n_end > QCOW_MAX_CRYPT_CLUSTERS * s->cluster_sectors) {
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-            n_end = QCOW_MAX_CRYPT_CLUSTERS * s->cluster_sectors;
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+            cur_nr_sectors >
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+            QCOW_MAX_CRYPT_CLUSTERS * s->cluster_sectors - index_in_cluster) {
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+            cur_nr_sectors =
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+                QCOW_MAX_CRYPT_CLUSTERS * s->cluster_sectors - index_in_cluster;
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         }
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         ret = qcow2_alloc_cluster_offset(bs, sector_num << 9,
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-            index_in_cluster, n_end, &cur_nr_sectors, &cluster_offset, &l2meta);
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+            &cur_nr_sectors, &cluster_offset, &l2meta);
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         if (ret < 0) {
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             goto fail;
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         }
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@@ -1408,7 +1409,7 @@ static int preallocate(BlockDriverState *bs)
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     while (nb_sectors) {
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         num = MIN(nb_sectors, INT_MAX >> 9);
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-        ret = qcow2_alloc_cluster_offset(bs, offset, 0, num, &num,
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+        ret = qcow2_alloc_cluster_offset(bs, offset, &num,
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                                          &host_offset, &meta);
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         if (ret < 0) {
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             return ret;
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diff --git a/block/qcow2.h b/block/qcow2.h
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index 9749f03..4a653c5 100644
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--- a/block/qcow2.h
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+++ b/block/qcow2.h
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@@ -463,7 +463,7 @@ void qcow2_encrypt_sectors(BDRVQcowState *s, int64_t sector_num,
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 int qcow2_get_cluster_offset(BlockDriverState *bs, uint64_t offset,
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     int *num, uint64_t *cluster_offset);
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 int qcow2_alloc_cluster_offset(BlockDriverState *bs, uint64_t offset,
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-    int n_start, int n_end, int *num, uint64_t *host_offset, QCowL2Meta **m);
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+    int *num, uint64_t *host_offset, QCowL2Meta **m);
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 uint64_t qcow2_alloc_compressed_cluster_offset(BlockDriverState *bs,
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                                          uint64_t offset,
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                                          int compressed_size);
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diff --git a/trace-events b/trace-events
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index 5d86cf3..b9144b2 100644
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--- a/trace-events
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+++ b/trace-events
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@@ -485,7 +485,7 @@ qcow2_writev_done_part(void *co, int cur_nr_sectors) "co %p cur_nr_sectors %d"
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 qcow2_writev_data(void *co, uint64_t offset) "co %p offset %" PRIx64
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 # block/qcow2-cluster.c
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-qcow2_alloc_clusters_offset(void *co, uint64_t offset, int n_start, int n_end) "co %p offet %" PRIx64 " n_start %d n_end %d"
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+qcow2_alloc_clusters_offset(void *co, uint64_t offset, int num) "co %p offet %" PRIx64 " num %d"
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 qcow2_handle_copied(void *co, uint64_t guest_offset, uint64_t host_offset, uint64_t bytes) "co %p guest_offet %" PRIx64 " host_offset %" PRIx64 " bytes %" PRIx64
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 qcow2_handle_alloc(void *co, uint64_t guest_offset, uint64_t host_offset, uint64_t bytes) "co %p guest_offet %" PRIx64 " host_offset %" PRIx64 " bytes %" PRIx64
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 qcow2_do_alloc_clusters_offset(void *co, uint64_t guest_offset, uint64_t host_offset, int nb_clusters) "co %p guest_offet %" PRIx64 " host_offset %" PRIx64 " nb_clusters %d"
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-- 
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1.7.1
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