102 lines
4.0 KiB
Diff
102 lines
4.0 KiB
Diff
From 3e603e344b81b3ecfea6fb9589ba91f70a22139d Mon Sep 17 00:00:00 2001
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From: Kevin Wolf <kwolf@redhat.com>
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Date: Mon, 8 Jun 2020 15:01:33 +0100
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Subject: [PATCH 05/17] qcow2: Support BDRV_REQ_ZERO_WRITE for truncate
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RH-Author: Kevin Wolf <kwolf@redhat.com>
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Message-id: <20200608150140.38218-5-kwolf@redhat.com>
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Patchwork-id: 97449
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O-Subject: [RHEL-AV-8.2.1 qemu-kvm PATCH 04/11] qcow2: Support BDRV_REQ_ZERO_WRITE for truncate
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Bugzilla: 1780574
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RH-Acked-by: Sergio Lopez Pascual <slp@redhat.com>
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RH-Acked-by: Eric Blake <eblake@redhat.com>
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RH-Acked-by: Max Reitz <mreitz@redhat.com>
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If BDRV_REQ_ZERO_WRITE is set and we're extending the image, calling
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qcow2_cluster_zeroize() with flags=0 does the right thing: It doesn't
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undo any previous preallocation, but just adds the zero flag to all
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relevant L2 entries. If an external data file is in use, a write_zeroes
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request to the data file is made instead.
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Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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Message-Id: <20200424125448.63318-5-kwolf@redhat.com>
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Reviewed-by: Eric Blake <eblake@redhat.com>
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Reviewed-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 f01643fb8b47e8a70c04bbf45e0f12a9e5bc54de)
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Signed-off-by: Kevin Wolf <kwolf@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/qcow2-cluster.c | 2 +-
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block/qcow2.c | 34 ++++++++++++++++++++++++++++++++++
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2 files changed, 35 insertions(+), 1 deletion(-)
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diff --git a/block/qcow2-cluster.c b/block/qcow2-cluster.c
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index dc3c270..9d04f8d 100644
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--- a/block/qcow2-cluster.c
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+++ b/block/qcow2-cluster.c
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@@ -1784,7 +1784,7 @@ int qcow2_cluster_zeroize(BlockDriverState *bs, uint64_t offset,
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/* Caller must pass aligned values, except at image end */
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assert(QEMU_IS_ALIGNED(offset, s->cluster_size));
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assert(QEMU_IS_ALIGNED(end_offset, s->cluster_size) ||
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- end_offset == bs->total_sectors << BDRV_SECTOR_BITS);
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+ end_offset >= bs->total_sectors << BDRV_SECTOR_BITS);
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/* The zero flag is only supported by version 3 and newer */
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if (s->qcow_version < 3) {
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diff --git a/block/qcow2.c b/block/qcow2.c
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index 86aa74a..f3d6cb0 100644
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--- a/block/qcow2.c
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+++ b/block/qcow2.c
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@@ -1726,6 +1726,7 @@ static int coroutine_fn qcow2_do_open(BlockDriverState *bs, QDict *options,
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}
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bs->supported_zero_flags = header.version >= 3 ? BDRV_REQ_MAY_UNMAP : 0;
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+ bs->supported_truncate_flags = BDRV_REQ_ZERO_WRITE;
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/* Repair image if dirty */
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if (!(flags & (BDRV_O_CHECK | BDRV_O_INACTIVE)) && !bs->read_only &&
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@@ -4197,6 +4198,39 @@ static int coroutine_fn qcow2_co_truncate(BlockDriverState *bs, int64_t offset,
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g_assert_not_reached();
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}
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+ if ((flags & BDRV_REQ_ZERO_WRITE) && offset > old_length) {
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+ uint64_t zero_start = QEMU_ALIGN_UP(old_length, s->cluster_size);
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+
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+ /*
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+ * Use zero clusters as much as we can. qcow2_cluster_zeroize()
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+ * requires a cluster-aligned start. The end may be unaligned if it is
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+ * at the end of the image (which it is here).
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+ */
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+ ret = qcow2_cluster_zeroize(bs, zero_start, offset - zero_start, 0);
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+ if (ret < 0) {
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+ error_setg_errno(errp, -ret, "Failed to zero out new clusters");
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+ goto fail;
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+ }
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+
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+ /* Write explicit zeros for the unaligned head */
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+ if (zero_start > old_length) {
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+ uint64_t len = zero_start - old_length;
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+ uint8_t *buf = qemu_blockalign0(bs, len);
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+ QEMUIOVector qiov;
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+ qemu_iovec_init_buf(&qiov, buf, len);
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+
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+ qemu_co_mutex_unlock(&s->lock);
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+ ret = qcow2_co_pwritev_part(bs, old_length, len, &qiov, 0, 0);
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+ qemu_co_mutex_lock(&s->lock);
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+
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+ qemu_vfree(buf);
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+ if (ret < 0) {
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+ error_setg_errno(errp, -ret, "Failed to zero out the new area");
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+ goto fail;
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+ }
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+ }
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+ }
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+
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if (prealloc != PREALLOC_MODE_OFF) {
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/* Flush metadata before actually changing the image size */
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ret = qcow2_write_caches(bs);
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--
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1.8.3.1
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