50 lines
2.1 KiB
Diff
50 lines
2.1 KiB
Diff
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From db04524f820582ebf1189223b6378de238511da1 Mon Sep 17 00:00:00 2001
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From: Kevin Wolf <kwolf@redhat.com>
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Date: Mon, 29 Apr 2019 12:52:21 +0200
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Subject: [PATCH] qcow2: Fix qcow2_make_empty() with external data file
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make_completely_empty() is an optimisated path for bdrv_make_empty()
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where completely new metadata is created inside the image file instead
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of going through all clusters and discarding them. For an external data
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file, however, we actually need to do discard operations on the data
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file; just overwriting the qcow2 file doesn't get rid of the data.
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The necessary slow path with an explicit discard operation already
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exists for other cases. Use it for external data files, too.
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Cc: qemu-stable@nongnu.org
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Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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Reviewed-by: Eric Blake <eblake@redhat.com>
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(cherry-picked from commit db04524f820582ebf1189223b6378de238511da1)
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---
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block/qcow2.c | 7 +++++--
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1 file changed, 5 insertions(+), 2 deletions(-)
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diff --git a/block/qcow2.c b/block/qcow2.c
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index 7fbef97aab..840f289a48 100644
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--- a/block/qcow2.c
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+++ b/block/qcow2.c
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@@ -4384,14 +4384,17 @@ static int qcow2_make_empty(BlockDriverState *bs)
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if (s->qcow_version >= 3 && !s->snapshots && !s->nb_bitmaps &&
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3 + l1_clusters <= s->refcount_block_size &&
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- s->crypt_method_header != QCOW_CRYPT_LUKS) {
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+ s->crypt_method_header != QCOW_CRYPT_LUKS &&
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+ !has_data_file(bs)) {
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/* The following function only works for qcow2 v3 images (it
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* requires the dirty flag) and only as long as there are no
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* features that reserve extra clusters (such as snapshots,
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* LUKS header, or persistent bitmaps), because it completely
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* empties the image. Furthermore, the L1 table and three
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* additional clusters (image header, refcount table, one
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- * refcount block) have to fit inside one refcount block. */
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+ * refcount block) have to fit inside one refcount block. It
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+ * only resets the image file, i.e. does not work with an
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+ * external data file. */
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return make_completely_empty(bs);
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}
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--
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2.19.1
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