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[PATCH v10 32/34] qcow2: Allow preallocation and backing files if extend
From: |
Alberto Garcia |
Subject: |
[PATCH v10 32/34] qcow2: Allow preallocation and backing files if extended_l2 is set |
Date: |
Fri, 3 Jul 2020 17:58:18 +0200 |
Traditional qcow2 images don't allow preallocation if a backing file
is set. This is because once a cluster is allocated there is no way to
tell that its data should be read from the backing file.
Extended L2 entries have individual allocation bits for each
subcluster, and therefore it is perfectly possible to have an
allocated cluster with all its subclusters unallocated.
Signed-off-by: Alberto Garcia <berto@igalia.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
---
block/qcow2.c | 7 ++++---
tests/qemu-iotests/206.out | 2 +-
2 files changed, 5 insertions(+), 4 deletions(-)
diff --git a/block/qcow2.c b/block/qcow2.c
index 3dfb56ccca..06e5c53b70 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -3451,10 +3451,11 @@ qcow2_co_create(BlockdevCreateOptions *create_options,
Error **errp)
qcow2_opts->preallocation = PREALLOC_MODE_OFF;
}
if (qcow2_opts->has_backing_file &&
- qcow2_opts->preallocation != PREALLOC_MODE_OFF)
+ qcow2_opts->preallocation != PREALLOC_MODE_OFF &&
+ !qcow2_opts->extended_l2)
{
- error_setg(errp, "Backing file and preallocation cannot be used at "
- "the same time");
+ error_setg(errp, "Backing file and preallocation can only be used at "
+ "the same time if extended_l2 is on");
ret = -EINVAL;
goto out;
}
diff --git a/tests/qemu-iotests/206.out b/tests/qemu-iotests/206.out
index 363c5abe35..a100849fcb 100644
--- a/tests/qemu-iotests/206.out
+++ b/tests/qemu-iotests/206.out
@@ -203,7 +203,7 @@ Job failed: Different refcount widths than 16 bits require
compatibility level 1
=== Invalid backing file options ===
{"execute": "blockdev-create", "arguments": {"job-id": "job0", "options":
{"backing-file": "/dev/null", "driver": "qcow2", "file": "node0",
"preallocation": "full", "size": 67108864}}}
{"return": {}}
-Job failed: Backing file and preallocation cannot be used at the same time
+Job failed: Backing file and preallocation can only be used at the same time
if extended_l2 is on
{"execute": "job-dismiss", "arguments": {"id": "job0"}}
{"return": {}}
--
2.20.1
- [PATCH v10 20/34] qcow2: Add subcluster support to calculate_l2_meta(), (continued)
- [PATCH v10 20/34] qcow2: Add subcluster support to calculate_l2_meta(), Alberto Garcia, 2020/07/03
- [PATCH v10 23/34] qcow2: Add subcluster support to discard_in_l2_slice(), Alberto Garcia, 2020/07/03
- [PATCH v10 26/34] qcow2: Clear the L2 bitmap when allocating a compressed cluster, Alberto Garcia, 2020/07/03
- [PATCH v10 22/34] qcow2: Add subcluster support to zero_in_l2_slice(), Alberto Garcia, 2020/07/03
- [PATCH v10 13/34] qcow2: Update get/set_l2_entry() and add get/set_l2_bitmap(), Alberto Garcia, 2020/07/03
- [PATCH v10 24/34] qcow2: Add subcluster support to check_refcounts_l2(), Alberto Garcia, 2020/07/03
- [PATCH v10 17/34] qcow2: Add cluster type parameter to qcow2_get_host_offset(), Alberto Garcia, 2020/07/03
- [PATCH v10 27/34] qcow2: Add subcluster support to handle_alloc_space(), Alberto Garcia, 2020/07/03
- [PATCH v10 29/34] qcow2: Add subcluster support to qcow2_measure(), Alberto Garcia, 2020/07/03
- [PATCH v10 30/34] qcow2: Add prealloc field to QCowL2Meta, Alberto Garcia, 2020/07/03
- [PATCH v10 32/34] qcow2: Allow preallocation and backing files if extended_l2 is set,
Alberto Garcia <=
- [PATCH v10 34/34] iotests: Add tests for qcow2 images with extended L2 entries, Alberto Garcia, 2020/07/03
- [PATCH v10 31/34] qcow2: Add the 'extended_l2' option and the QCOW2_INCOMPAT_EXTL2 bit, Alberto Garcia, 2020/07/03