From: Max Reitz <mreitz@redhat.com>
To: qemu-block@nongnu.org
Cc: Kevin Wolf <kwolf@redhat.com>,
qemu-devel@nongnu.org, Max Reitz <mreitz@redhat.com>
Subject: [Qemu-devel] [PATCH for-4.2 06/13] qcow2: Separate qcow2_check_read_snapshot_table()
Date: Tue, 30 Jul 2019 19:25:01 +0200 [thread overview]
Message-ID: <20190730172508.19911-7-mreitz@redhat.com> (raw)
In-Reply-To: <20190730172508.19911-1-mreitz@redhat.com>
Reading the snapshot table can fail. That is a problem when we want to
repair the image.
Therefore, stop reading the snapshot table in qcow2_do_open() in check
mode. Instead, add a new function qcow2_check_read_snapshot_table()
that reads the snapshot table at a later point. In the future, we want
to handle errors here and fix them.
Signed-off-by: Max Reitz <mreitz@redhat.com>
---
block/qcow2.h | 4 +++
block/qcow2-snapshot.c | 58 ++++++++++++++++++++++++++++++++
block/qcow2.c | 76 ++++++++++++++++++++++++++++++++----------
3 files changed, 120 insertions(+), 18 deletions(-)
diff --git a/block/qcow2.h b/block/qcow2.h
index 77586d81b9..50c7eefb5b 100644
--- a/block/qcow2.h
+++ b/block/qcow2.h
@@ -712,6 +712,10 @@ void qcow2_free_snapshots(BlockDriverState *bs);
int qcow2_read_snapshots(BlockDriverState *bs, Error **errp);
int qcow2_write_snapshots(BlockDriverState *bs);
+int coroutine_fn qcow2_check_read_snapshot_table(BlockDriverState *bs,
+ BdrvCheckResult *result,
+ BdrvCheckMode fix);
+
/* qcow2-cache.c functions */
Qcow2Cache *qcow2_cache_create(BlockDriverState *bs, int num_tables,
unsigned table_size);
diff --git a/block/qcow2-snapshot.c b/block/qcow2-snapshot.c
index 3d097b92d7..cbc6d699b6 100644
--- a/block/qcow2-snapshot.c
+++ b/block/qcow2-snapshot.c
@@ -321,6 +321,64 @@ fail:
return ret;
}
+int coroutine_fn qcow2_check_read_snapshot_table(BlockDriverState *bs,
+ BdrvCheckResult *result,
+ BdrvCheckMode fix)
+{
+ BDRVQcow2State *s = bs->opaque;
+ Error *local_err = NULL;
+ int ret;
+ struct {
+ uint32_t nb_snapshots;
+ uint64_t snapshots_offset;
+ } QEMU_PACKED snapshot_table_pointer;
+
+ /* qcow2_do_open() discards this information in check mode */
+ ret = bdrv_pread(bs->file, 60, &snapshot_table_pointer,
+ sizeof(snapshot_table_pointer));
+ if (ret < 0) {
+ result->check_errors++;
+ fprintf(stderr, "ERROR failed to read the snapshot table pointer from "
+ "the image header: %s\n", strerror(-ret));
+ return ret;
+ }
+
+ s->snapshots_offset = be64_to_cpu(snapshot_table_pointer.snapshots_offset);
+ s->nb_snapshots = be32_to_cpu(snapshot_table_pointer.nb_snapshots);
+
+ ret = qcow2_validate_table(bs, s->snapshots_offset, s->nb_snapshots,
+ sizeof(QCowSnapshotHeader),
+ sizeof(QCowSnapshotHeader) * QCOW_MAX_SNAPSHOTS,
+ "snapshot table", &local_err);
+ if (ret < 0) {
+ result->check_errors++;
+ error_reportf_err(local_err, "ERROR ");
+
+ /* We did not read the snapshot table, so invalidate this information */
+ s->snapshots_offset = 0;
+ s->nb_snapshots = 0;
+
+ return ret;
+ }
+
+ qemu_co_mutex_unlock(&s->lock);
+ ret = qcow2_read_snapshots(bs, &local_err);
+ qemu_co_mutex_lock(&s->lock);
+ if (ret < 0) {
+ result->check_errors++;
+ error_reportf_err(local_err,
+ "ERROR failed to read the snapshot table: ");
+
+ /* We did not read the snapshot table, so invalidate this information */
+ s->snapshots_offset = 0;
+ s->nb_snapshots = 0;
+
+ return ret;
+ }
+
+ return 0;
+}
+
static void find_new_snapshot_id(BlockDriverState *bs,
char *id_str, int id_str_size)
{
diff --git a/block/qcow2.c b/block/qcow2.c
index 75d41683a1..2983a7795a 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -567,11 +567,40 @@ int qcow2_mark_consistent(BlockDriverState *bs)
return 0;
}
+static void qcow2_add_check_result(BdrvCheckResult *out,
+ const BdrvCheckResult *src,
+ bool set_allocation_info)
+{
+ out->corruptions += src->corruptions;
+ out->leaks += src->leaks;
+ out->check_errors += src->check_errors;
+ out->corruptions_fixed += src->corruptions_fixed;
+ out->leaks_fixed += src->leaks_fixed;
+
+ if (set_allocation_info) {
+ out->image_end_offset = src->image_end_offset;
+ out->bfi = src->bfi;
+ }
+}
+
static int coroutine_fn qcow2_co_check_locked(BlockDriverState *bs,
BdrvCheckResult *result,
BdrvCheckMode fix)
{
- int ret = qcow2_check_refcounts(bs, result, fix);
+ BdrvCheckResult snapshot_res = {};
+ BdrvCheckResult refcount_res = {};
+ int ret;
+
+ memset(result, 0, sizeof(*result));
+
+ ret = qcow2_check_read_snapshot_table(bs, &snapshot_res, fix);
+ qcow2_add_check_result(result, &snapshot_res, false);
+ if (ret < 0) {
+ return ret;
+ }
+
+ ret = qcow2_check_refcounts(bs, &refcount_res, fix);
+ qcow2_add_check_result(result, &refcount_res, true);
if (ret < 0) {
return ret;
}
@@ -1403,17 +1432,22 @@ static int coroutine_fn qcow2_do_open(BlockDriverState *bs, QDict *options,
goto fail;
}
- /* The total size in bytes of the snapshot table is checked in
- * qcow2_read_snapshots() because the size of each snapshot is
- * variable and we don't know it yet.
- * Here we only check the offset and number of snapshots. */
- ret = qcow2_validate_table(bs, header.snapshots_offset,
- header.nb_snapshots,
- sizeof(QCowSnapshotHeader),
- sizeof(QCowSnapshotHeader) * QCOW_MAX_SNAPSHOTS,
- "Snapshot table", errp);
- if (ret < 0) {
- goto fail;
+ if (!(flags & BDRV_O_CHECK)) {
+ /*
+ * The total size in bytes of the snapshot table is checked in
+ * qcow2_read_snapshots() because the size of each snapshot is
+ * variable and we don't know it yet.
+ * Here we only check the offset and number of snapshots.
+ */
+ ret = qcow2_validate_table(bs, header.snapshots_offset,
+ header.nb_snapshots,
+ sizeof(QCowSnapshotHeader),
+ sizeof(QCowSnapshotHeader) *
+ QCOW_MAX_SNAPSHOTS,
+ "Snapshot table", errp);
+ if (ret < 0) {
+ goto fail;
+ }
}
/* read the level 1 table */
@@ -1573,13 +1607,19 @@ static int coroutine_fn qcow2_do_open(BlockDriverState *bs, QDict *options,
s->image_backing_file = g_strdup(bs->auto_backing_file);
}
- /* Internal snapshots */
- s->snapshots_offset = header.snapshots_offset;
- s->nb_snapshots = header.nb_snapshots;
+ /*
+ * Internal snapshots; skip reading them in check mode, because
+ * we do not need them then, and we do not want to abort because
+ * of a broken table.
+ */
+ if (!(flags & BDRV_O_CHECK)) {
+ s->snapshots_offset = header.snapshots_offset;
+ s->nb_snapshots = header.nb_snapshots;
- ret = qcow2_read_snapshots(bs, errp);
- if (ret < 0) {
- goto fail;
+ ret = qcow2_read_snapshots(bs, errp);
+ if (ret < 0) {
+ goto fail;
+ }
}
/* Clear unknown autoclear feature bits */
--
2.21.0
next prev parent reply other threads:[~2019-07-30 17:35 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-30 17:24 [Qemu-devel] [PATCH for-4.2 00/13] qcow2: Let check -r all repair some snapshot bits Max Reitz
2019-07-30 17:24 ` [Qemu-devel] [PATCH for-4.2 01/13] qcow2: Add Error ** to qcow2_read_snapshots() Max Reitz
2019-07-30 17:41 ` Eric Blake
2019-07-30 17:24 ` [Qemu-devel] [PATCH for-4.2 02/13] qcow2: Keep unknown extra snapshot data Max Reitz
2019-07-30 17:56 ` Eric Blake
2019-07-31 8:54 ` Max Reitz
2019-08-16 2:09 ` Max Reitz
2019-07-30 17:24 ` [Qemu-devel] [PATCH for-4.2 03/13] qcow2: Make qcow2_write_snapshots() public Max Reitz
2019-07-30 17:57 ` Eric Blake
2019-07-30 17:24 ` [Qemu-devel] [PATCH for-4.2 04/13] qcow2: Put qcow2_upgrade() into an own function Max Reitz
2019-07-30 18:00 ` Eric Blake
2019-07-30 17:25 ` [Qemu-devel] [PATCH for-4.2 05/13] qcow2: Write v3-compliant snapshot list on upgrade Max Reitz
2019-07-30 18:10 ` Eric Blake
2019-07-31 8:56 ` Max Reitz
2019-07-30 17:25 ` Max Reitz [this message]
2019-07-30 18:53 ` [Qemu-devel] [PATCH for-4.2 06/13] qcow2: Separate qcow2_check_read_snapshot_table() Eric Blake
2019-07-31 8:59 ` Max Reitz
2019-07-30 17:25 ` [Qemu-devel] [PATCH for-4.2 07/13] qcow2: Add qcow2_check_fix_snapshot_table() Max Reitz
2019-07-30 18:54 ` Eric Blake
2019-07-30 17:25 ` [Qemu-devel] [PATCH for-4.2 08/13] qcow2: Fix broken snapshot table entries Max Reitz
2019-07-30 19:02 ` Eric Blake
2019-07-31 9:06 ` Max Reitz
2019-07-30 17:25 ` [Qemu-devel] [PATCH for-4.2 09/13] qcow2: Fix overly long snapshot tables Max Reitz
2019-07-30 19:08 ` Eric Blake
2019-07-31 9:22 ` Max Reitz
2019-08-16 18:06 ` Max Reitz
2019-07-30 17:25 ` [Qemu-devel] [PATCH for-4.2 10/13] qcow2: Repair snapshot table with too many entries Max Reitz
2019-07-30 19:10 ` Eric Blake
2019-07-31 9:25 ` Max Reitz
2019-07-30 17:25 ` [Qemu-devel] [PATCH for-4.2 11/13] qcow2: Fix v3 snapshot table entry compliancy Max Reitz
2019-07-30 19:12 ` Eric Blake
2019-07-30 17:25 ` [Qemu-devel] [PATCH for-4.2 12/13] iotests: Add peek_file* functions Max Reitz
2019-07-30 19:22 ` Eric Blake
2019-07-31 9:27 ` Max Reitz
2019-07-30 17:25 ` [Qemu-devel] [PATCH for-4.2 13/13] iotests: Test qcow2's snapshot table handling Max Reitz
2019-07-30 19:56 ` Eric Blake
2019-07-31 9:36 ` Max Reitz
2019-07-30 17:39 ` [Qemu-devel] [PATCH for-4.2 00/13] qcow2: Let check -r all repair some snapshot bits Eric Blake
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