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[PATCH v11 24/34] qcow2: Add subcluster support to check_refcounts_l2()
From: |
Alberto Garcia |
Subject: |
[PATCH v11 24/34] qcow2: Add subcluster support to check_refcounts_l2() |
Date: |
Fri, 10 Jul 2020 18:13:06 +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>
Reviewed-by: Max Reitz <mreitz@redhat.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 v11 04/34] qcow2: Split cluster_needs_cow() out of count_cow_clusters(), (continued)
- [PATCH v11 04/34] qcow2: Split cluster_needs_cow() out of count_cow_clusters(), Alberto Garcia, 2020/07/10
- [PATCH v11 07/34] qcow2: Document the Extended L2 Entries feature, Alberto Garcia, 2020/07/10
- [PATCH v11 05/34] qcow2: Process QCOW2_CLUSTER_ZERO_ALLOC clusters in handle_copied(), Alberto Garcia, 2020/07/10
- [PATCH v11 13/34] qcow2: Update get/set_l2_entry() and add get/set_l2_bitmap(), Alberto Garcia, 2020/07/10
- [PATCH v11 15/34] qcow2: Add qcow2_get_subcluster_range_type(), Alberto Garcia, 2020/07/10
- [PATCH v11 19/34] qcow2: Handle QCOW2_SUBCLUSTER_UNALLOCATED_ALLOC, Alberto Garcia, 2020/07/10
- [PATCH v11 09/34] qcow2: Add subcluster-related fields to BDRVQcow2State, Alberto Garcia, 2020/07/10
- [PATCH v11 20/34] qcow2: Add subcluster support to calculate_l2_meta(), Alberto Garcia, 2020/07/10
- [PATCH v11 18/34] qcow2: Replace QCOW2_CLUSTER_* with QCOW2_SUBCLUSTER_*, Alberto Garcia, 2020/07/10
- [PATCH v11 22/34] qcow2: Add subcluster support to zero_in_l2_slice(), Alberto Garcia, 2020/07/10
- [PATCH v11 24/34] qcow2: Add subcluster support to check_refcounts_l2(),
Alberto Garcia <=
- [PATCH v11 10/34] qcow2: Add offset_to_sc_index(), Alberto Garcia, 2020/07/10
- [PATCH v11 11/34] qcow2: Add offset_into_subcluster() and size_to_subclusters(), Alberto Garcia, 2020/07/10
- [PATCH v11 12/34] qcow2: Add l2_entry_size(), Alberto Garcia, 2020/07/10
- [PATCH v11 32/34] qcow2: Allow preallocation and backing files if extended_l2 is set, Alberto Garcia, 2020/07/10
- [PATCH v11 25/34] qcow2: Update L2 bitmap in qcow2_alloc_cluster_link_l2(), Alberto Garcia, 2020/07/10
- [PATCH v11 26/34] qcow2: Clear the L2 bitmap when allocating a compressed cluster, Alberto Garcia, 2020/07/10
- [PATCH v11 14/34] qcow2: Add QCow2SubclusterType and qcow2_get_subcluster_type(), Alberto Garcia, 2020/07/10
- [PATCH v11 17/34] qcow2: Add cluster type parameter to qcow2_get_host_offset(), Alberto Garcia, 2020/07/10
- [PATCH v11 28/34] qcow2: Add subcluster support to qcow2_co_pwrite_zeroes(), Alberto Garcia, 2020/07/10
- [PATCH v11 30/34] qcow2: Add prealloc field to QCowL2Meta, Alberto Garcia, 2020/07/10