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[PATCH v9 24/34] qcow2: Add subcluster support to check_refcounts_l2()
From: |
Alberto Garcia |
Subject: |
[PATCH v9 24/34] qcow2: Add subcluster support to check_refcounts_l2() |
Date: |
Sun, 28 Jun 2020 13:02:33 +0200 |
The offset field of an uncompressed cluster's L2 entry must be aligned
to the cluster size, otherwise it is invalid. If the cluster has no
data then it means that the offset points to a preallocation, so we
can clear the offset field without affecting the guest-visible data.
This is what 'qemu-img check' does when run in repair mode.
On traditional qcow2 images this can only happen when QCOW_OFLAG_ZERO
is set, and repairing such entries turns the clusters from ZERO_ALLOC
into ZERO_PLAIN.
Extended L2 entries have no ZERO_ALLOC clusters and no QCOW_OFLAG_ZERO
but the idea is the same: if none of the subclusters are allocated
then we can clear the offset field and leave the bitmap untouched.
Signed-off-by: Alberto Garcia <berto@igalia.com>
---
block/qcow2-refcount.c | 16 +++++++++++-----
tests/qemu-iotests/060.out | 2 +-
2 files changed, 12 insertions(+), 6 deletions(-)
diff --git a/block/qcow2-refcount.c b/block/qcow2-refcount.c
index 770c5dbc83..aae52607eb 100644
--- a/block/qcow2-refcount.c
+++ b/block/qcow2-refcount.c
@@ -1669,12 +1669,18 @@ static int check_refcounts_l2(BlockDriverState *bs,
BdrvCheckResult *res,
/* Correct offsets are cluster aligned */
if (offset_into_cluster(s, offset)) {
+ bool contains_data;
res->corruptions++;
- if (qcow2_get_cluster_type(bs, l2_entry) ==
- QCOW2_CLUSTER_ZERO_ALLOC)
- {
- fprintf(stderr, "%s offset=%" PRIx64 ": Preallocated zero "
+ if (has_subclusters(s)) {
+ uint64_t l2_bitmap = get_l2_bitmap(s, l2_table, i);
+ contains_data = (l2_bitmap & QCOW_L2_BITMAP_ALL_ALLOC);
+ } else {
+ contains_data = !(l2_entry & QCOW_OFLAG_ZERO);
+ }
+
+ if (!contains_data) {
+ fprintf(stderr, "%s offset=%" PRIx64 ": Preallocated "
"cluster is not properly aligned; L2 entry "
"corrupted.\n",
fix & BDRV_FIX_ERRORS ? "Repairing" : "ERROR",
@@ -1686,7 +1692,7 @@ static int check_refcounts_l2(BlockDriverState *bs,
BdrvCheckResult *res,
int ign = active ? QCOW2_OL_ACTIVE_L2 :
QCOW2_OL_INACTIVE_L2;
- l2_entry = QCOW_OFLAG_ZERO;
+ l2_entry = has_subclusters(s) ? 0 : QCOW_OFLAG_ZERO;
set_l2_entry(s, l2_table, i, l2_entry);
ret = qcow2_pre_write_overlap_check(bs, ign,
l2e_offset, l2_entry_size(s), false);
diff --git a/tests/qemu-iotests/060.out b/tests/qemu-iotests/060.out
index be5f8707a3..fa3d68f0df 100644
--- a/tests/qemu-iotests/060.out
+++ b/tests/qemu-iotests/060.out
@@ -320,7 +320,7 @@ discard 65536/65536 bytes at offset 0
qcow2: Marking image as corrupt: Preallocated zero cluster offset 0x2a00
unaligned (guest offset: 0); further corruption events will be suppressed
write failed: Input/output error
--- Repairing ---
-Repairing offset=2a00: Preallocated zero cluster is not properly aligned; L2
entry corrupted.
+Repairing offset=2a00: Preallocated cluster is not properly aligned; L2 entry
corrupted.
The following inconsistencies were found and repaired:
0 leaked clusters
--
2.20.1
- [PATCH v9 26/34] qcow2: Clear the L2 bitmap when allocating a compressed cluster, (continued)
- [PATCH v9 26/34] qcow2: Clear the L2 bitmap when allocating a compressed cluster, Alberto Garcia, 2020/06/28
- [PATCH v9 03/34] qcow2: Add calculate_l2_meta(), Alberto Garcia, 2020/06/28
- [PATCH v9 04/34] qcow2: Split cluster_needs_cow() out of count_cow_clusters(), Alberto Garcia, 2020/06/28
- [PATCH v9 06/34] qcow2: Add get_l2_entry() and set_l2_entry(), Alberto Garcia, 2020/06/28
- [PATCH v9 10/34] qcow2: Add offset_to_sc_index(), Alberto Garcia, 2020/06/28
- [PATCH v9 08/34] qcow2: Add dummy has_subclusters() function, Alberto Garcia, 2020/06/28
- [PATCH v9 05/34] qcow2: Process QCOW2_CLUSTER_ZERO_ALLOC clusters in handle_copied(), Alberto Garcia, 2020/06/28
- [PATCH v9 02/34] qcow2: Convert qcow2_get_cluster_offset() into qcow2_get_host_offset(), Alberto Garcia, 2020/06/28
- [PATCH v9 07/34] qcow2: Document the Extended L2 Entries feature, Alberto Garcia, 2020/06/28
- [PATCH v9 13/34] qcow2: Update get/set_l2_entry() and add get/set_l2_bitmap(), Alberto Garcia, 2020/06/28
- [PATCH v9 24/34] qcow2: Add subcluster support to check_refcounts_l2(),
Alberto Garcia <=
- [PATCH v9 29/34] qcow2: Add subcluster support to qcow2_measure(), Alberto Garcia, 2020/06/28
- [PATCH v9 22/34] qcow2: Add subcluster support to zero_in_l2_slice(), Alberto Garcia, 2020/06/28
- [PATCH v9 19/34] qcow2: Handle QCOW2_SUBCLUSTER_UNALLOCATED_ALLOC, Alberto Garcia, 2020/06/28
- [PATCH v9 09/34] qcow2: Add subcluster-related fields to BDRVQcow2State, Alberto Garcia, 2020/06/28
- [PATCH v9 11/34] qcow2: Add offset_into_subcluster() and size_to_subclusters(), Alberto Garcia, 2020/06/28
- [PATCH v9 16/34] qcow2: Add qcow2_cluster_is_allocated(), Alberto Garcia, 2020/06/28
- [PATCH v9 30/34] qcow2: Add prealloc field to QCowL2Meta, Alberto Garcia, 2020/06/28
- [PATCH v9 25/34] qcow2: Update L2 bitmap in qcow2_alloc_cluster_link_l2(), Alberto Garcia, 2020/06/28
- [PATCH v9 01/34] qcow2: Make Qcow2AioTask store the full host offset, Alberto Garcia, 2020/06/28
- [PATCH v9 33/34] qcow2: Assert that expand_zero_clusters_in_l1() does not support subclusters, Alberto Garcia, 2020/06/28