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[PATCH v2 2/3] parallels: Add checking and repairing duplicate offsets i
From: |
alexander . ivanov |
Subject: |
[PATCH v2 2/3] parallels: Add checking and repairing duplicate offsets in BAT |
Date: |
Fri, 5 Aug 2022 17:47:51 +0200 |
From: Alexander Ivanov <alexander.ivanov@virtuozzo.com>
There could be corruptions in the image file:
two guest memory areas refer to the same host cluster.
If a duplicate offset is found fix it by copying the content
of the referred cluster to a new allocated cluster and
replace one of the two referring entries by the new cluster offset.
Signed-off-by: Natalia Kuzmina <natalia.kuzmina@openvz.org>
Signed-off-by: Alexander Ivanov <alexander.ivanov@virtuozzo.com>
---
block/parallels.c | 135 ++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 135 insertions(+)
diff --git a/block/parallels.c b/block/parallels.c
index a0eb7ec3c3..73264b4bd1 100644
--- a/block/parallels.c
+++ b/block/parallels.c
@@ -64,6 +64,11 @@ static QEnumLookup prealloc_mode_lookup = {
#define PARALLELS_OPT_PREALLOC_MODE "prealloc-mode"
#define PARALLELS_OPT_PREALLOC_SIZE "prealloc-size"
+#define REVERSED_BAT_UNTOUCHED 0xFFFFFFFF
+
+#define HOST_CLUSTER_INDEX(s, off) \
+ ((off - ((s->header->data_off) << BDRV_SECTOR_BITS)) / (s->cluster_size))
+
static QemuOptsList parallels_runtime_opts = {
.name = "parallels",
.head = QTAILQ_HEAD_INITIALIZER(parallels_runtime_opts.head),
@@ -559,6 +564,131 @@ static int check_leak(BlockDriverState *bs,
return 0;
}
+static int check_duplicate(BlockDriverState *bs,
+ BdrvCheckResult *res,
+ BdrvCheckMode fix)
+{
+ BDRVParallelsState *s = bs->opaque;
+ QEMUIOVector qiov;
+ int64_t off, high_off, size, sector_num;
+ uint32_t i, idx_host;
+ int ret = 0, n;
+ g_autofree uint32_t *reversed_bat = NULL;
+ g_autofree int64_t *cluster_buf = NULL;
+ bool sync_and_truncate = false;
+
+ /*
+ * Make a reversed BAT.
+ * Each cluster in the host file could represent only one cluster
+ * from the guest point of view. Reversed BAT provides mapping of that
type.
+ * Initially the table is filled with REVERSED_BAT_UNTOUCHED values.
+ */
+ reversed_bat = g_malloc(s->bat_size * sizeof(uint32_t));
+ for (i = 0; i < s->bat_size; i++) {
+ reversed_bat[i] = REVERSED_BAT_UNTOUCHED;
+ }
+
+ cluster_buf = g_malloc(s->cluster_size);
+ qemu_iovec_init(&qiov, 0);
+ qemu_iovec_add(&qiov, cluster_buf, s->cluster_size);
+
+ high_off = 0;
+ for (i = 0; i < s->bat_size; i++) {
+ off = bat2sect(s, i) << BDRV_SECTOR_BITS;
+ if (off == 0) {
+ continue;
+ }
+
+ if (off > high_off) {
+ high_off = off;
+ }
+
+ idx_host = HOST_CLUSTER_INDEX(s, off);
+ if (idx_host >= s->bat_size) {
+ res->check_errors++;
+ goto out;
+ }
+
+ if (reversed_bat[idx_host] != REVERSED_BAT_UNTOUCHED) {
+ /*
+ * We have alreade written a guest cluster index for this
+ * host cluster. It means there is a duplicated offset in BAT.
+ */
+ fprintf(stderr,
+ "%s BAT offset in entry %u duplicates offset in entry
%u\n",
+ fix & BDRV_FIX_ERRORS ? "Repairing" : "ERROR",
+ i, reversed_bat[idx_host]);
+ res->corruptions++;
+
+ if (fix & BDRV_FIX_ERRORS) {
+ /*
+ * Write zero to the current BAT entry, allocate a new cluster
+ * for the relevant guest offset and copy the host cluster
+ * to the new allocated cluster.
+ * In this way mwe will have two identical clusters and two
+ * BAT entries with the offsets of these clusters.
+ */
+ s->bat_bitmap[i] = 0;
+
+ sector_num = bat2sect(s, reversed_bat[idx_host]);
+ ret = bdrv_pread(bs->file, sector_num << BDRV_SECTOR_BITS,
+ s->cluster_size, cluster_buf, 0);
+ if (ret < 0) {
+ res->check_errors++;
+ goto out;
+ }
+
+ sector_num = (i * s->cluster_size) >> BDRV_SECTOR_BITS;
+ off = allocate_clusters(bs, sector_num, s->tracks, &n);
+ if (off < 0) {
+ res->check_errors++;
+ ret = off;
+ goto out;
+ }
+ off <<= BDRV_SECTOR_BITS;
+
+ ret = bdrv_co_pwritev(bs->file, off, s->cluster_size, &qiov,
0);
+ if (ret < 0) {
+ res->check_errors++;
+ goto out;
+ }
+
+ /* off is new and we should repair idx_host accordingly. */
+ idx_host = HOST_CLUSTER_INDEX(s, off);
+ res->corruptions_fixed++;
+ sync_and_truncate = true;
+ }
+ }
+ reversed_bat[idx_host] = i;
+ }
+
+ if (sync_and_truncate) {
+ ret = sync_header(bs, res);
+ if (ret < 0) {
+ goto out;
+ }
+
+ size = bdrv_getlength(bs->file->bs);
+ if (size < 0) {
+ res->check_errors++;
+ ret = size;
+ goto out;
+ }
+
+ res->image_end_offset = high_off + s->cluster_size;
+ if (size > res->image_end_offset) {
+ ret = truncate_file(bs, res->image_end_offset);
+ if (ret < 0) {
+ goto out;
+ }
+ }
+ }
+
+out:
+ qemu_iovec_destroy(&qiov);
+ return ret;
+}
+
static void collect_statistics(BlockDriverState *bs, BdrvCheckResult *res)
{
BDRVParallelsState *s = bs->opaque;
@@ -598,6 +728,11 @@ static int coroutine_fn
parallels_co_check(BlockDriverState *bs,
goto out;
}
+ ret = check_duplicate(bs, res, fix);
+ if (ret != 0) {
+ goto out;
+ }
+
collect_statistics(bs, res);
out:
--
2.34.1