ed1eefd2ae
- Fix ksm initscript errors on kernel missing ksm (#527653) - Add missing Requires(post): getent, useradd, groupadd (#527087)
141 lines
5.5 KiB
Diff
141 lines
5.5 KiB
Diff
From 1df18d4a961a66b9ea28ab83b409f4d9d470f148 Mon Sep 17 00:00:00 2001
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From: Kevin Wolf <kwolf@redhat.com>
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Date: Thu, 8 Oct 2009 15:02:08 +0200
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Subject: [PATCH] qcow2: Bring synchronous read/write back to life
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When the synchronous read and write functions were dropped, they were replaced
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by generic emulation functions. Unfortunately, these emulation functions don't
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provide the same semantics as the original functions did.
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The original bdrv_read would mean that we read some data synchronously and that
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we won't be interrupted during this read. The latter assumption is no longer
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true with the emulation function which needs to use qemu_aio_poll and therefore
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allows the callback of any other concurrent AIO request to be run during the
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read. Which in turn means that (meta)data read earlier could have changed and
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be invalid now. qcow2 is not prepared to work in this way and it's just scary
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how many places there are where other requests could run.
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I'm not sure yet where exactly it breaks, but you'll see breakage with virtio
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on qcow2 with a backing file. Providing synchronous functions again fixes the
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problem for me.
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Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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Signed-off-by: Mark McLoughlin <markmc@redhat.com>
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Fedora-patch: qemu-fix-qcow2-backing-file-with-virtio.patch
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---
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block/qcow2-cluster.c | 6 ++--
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block/qcow2.c | 51 +++++++++++++++++++++++++++++++++++++++++++++++-
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block/qcow2.h | 3 ++
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3 files changed, 55 insertions(+), 5 deletions(-)
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diff --git a/block/qcow2-cluster.c b/block/qcow2-cluster.c
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index d4631c3..4d0ce16 100644
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--- a/block/qcow2-cluster.c
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+++ b/block/qcow2-cluster.c
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@@ -306,8 +306,8 @@ void qcow2_encrypt_sectors(BDRVQcowState *s, int64_t sector_num,
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}
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-static int qcow_read(BlockDriverState *bs, int64_t sector_num,
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- uint8_t *buf, int nb_sectors)
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+int qcow2_read(BlockDriverState *bs, int64_t sector_num, uint8_t *buf,
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+ int nb_sectors)
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{
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BDRVQcowState *s = bs->opaque;
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int ret, index_in_cluster, n, n1;
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@@ -358,7 +358,7 @@ static int copy_sectors(BlockDriverState *bs, uint64_t start_sect,
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n = n_end - n_start;
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if (n <= 0)
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return 0;
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- ret = qcow_read(bs, start_sect + n_start, s->cluster_data, n);
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+ ret = qcow2_read(bs, start_sect + n_start, s->cluster_data, n);
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if (ret < 0)
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return ret;
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if (s->crypt_method) {
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diff --git a/block/qcow2.c b/block/qcow2.c
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index dd32ea2..ced257e 100644
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--- a/block/qcow2.c
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+++ b/block/qcow2.c
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@@ -855,6 +855,51 @@ static int qcow_make_empty(BlockDriverState *bs)
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return 0;
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}
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+static int qcow2_write(BlockDriverState *bs, int64_t sector_num,
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+ const uint8_t *buf, int nb_sectors)
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+{
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+ BDRVQcowState *s = bs->opaque;
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+ int ret, index_in_cluster, n;
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+ uint64_t cluster_offset;
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+ int n_end;
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+ QCowL2Meta l2meta;
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+
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+ while (nb_sectors > 0) {
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+ memset(&l2meta, 0, sizeof(l2meta));
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+
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+ index_in_cluster = sector_num & (s->cluster_sectors - 1);
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+ n_end = index_in_cluster + nb_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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+ cluster_offset = qcow2_alloc_cluster_offset(bs, sector_num << 9,
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+ index_in_cluster,
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+ n_end, &n, &l2meta);
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+ if (!cluster_offset)
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+ return -1;
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+ if (s->crypt_method) {
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+ qcow2_encrypt_sectors(s, sector_num, s->cluster_data, buf, n, 1,
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+ &s->aes_encrypt_key);
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+ ret = bdrv_pwrite(s->hd, cluster_offset + index_in_cluster * 512,
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+ s->cluster_data, n * 512);
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+ } else {
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+ ret = bdrv_pwrite(s->hd, cluster_offset + index_in_cluster * 512, buf, n * 512);
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+ }
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+ if (ret != n * 512 || qcow2_alloc_cluster_link_l2(bs, cluster_offset, &l2meta) < 0) {
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+ qcow2_free_any_clusters(bs, cluster_offset, l2meta.nb_clusters);
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+ return -1;
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+ }
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+ nb_sectors -= n;
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+ sector_num += n;
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+ buf += n * 512;
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+ if (l2meta.nb_clusters != 0) {
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+ LIST_REMOVE(&l2meta, next_in_flight);
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+ }
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+ }
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+ s->cluster_cache_offset = -1; /* disable compressed cache */
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+ return 0;
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+}
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+
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/* XXX: put compressed sectors first, then all the cluster aligned
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tables to avoid losing bytes in alignment */
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static int qcow_write_compressed(BlockDriverState *bs, int64_t sector_num,
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@@ -1037,8 +1082,10 @@ static BlockDriver bdrv_qcow2 = {
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.bdrv_set_key = qcow_set_key,
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.bdrv_make_empty = qcow_make_empty,
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- .bdrv_aio_readv = qcow_aio_readv,
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- .bdrv_aio_writev = qcow_aio_writev,
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+ .bdrv_read = qcow2_read,
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+ .bdrv_write = qcow2_write,
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+ .bdrv_aio_readv = qcow_aio_readv,
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+ .bdrv_aio_writev = qcow_aio_writev,
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.bdrv_write_compressed = qcow_write_compressed,
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.bdrv_snapshot_create = qcow2_snapshot_create,
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diff --git a/block/qcow2.h b/block/qcow2.h
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index 965a2f4..b41aa63 100644
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--- a/block/qcow2.h
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+++ b/block/qcow2.h
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@@ -202,6 +202,9 @@ uint64_t qcow2_alloc_compressed_cluster_offset(BlockDriverState *bs,
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int qcow2_alloc_cluster_link_l2(BlockDriverState *bs, uint64_t cluster_offset,
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QCowL2Meta *m);
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+int qcow2_read(BlockDriverState *bs, int64_t sector_num, uint8_t *buf,
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+ int nb_sectors);
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+
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/* qcow2-snapshot.c functions */
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int qcow2_snapshot_create(BlockDriverState *bs, QEMUSnapshotInfo *sn_info);
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int qcow2_snapshot_goto(BlockDriverState *bs, const char *snapshot_id);
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--
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1.6.2.5
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