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/*
* QEMU Enhanced Disk Format Consistency Check
*
* Copyright IBM, Corp. 2010
*
* Authors:
* Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
*
* This work is licensed under the terms of the GNU LGPL, version 2 or later.
* See the COPYING.LIB file in the top-level directory.
*
*/
#include "qed.h"
typedef struct {
BDRVQEDState *s;
BdrvCheckResult *result;
bool fix; /* whether to fix invalid offsets */
size_t nclusters;
uint32_t *used_clusters; /* referenced cluster bitmap */
QEDRequest request;
} QEDCheck;
static bool qed_test_bit(uint32_t *bitmap, uint64_t n) {
return !!(bitmap[n / 32] & (1 << (n % 32)));
}
static void qed_set_bit(uint32_t *bitmap, uint64_t n) {
bitmap[n / 32] |= 1 << (n % 32);
}
/**
* Set bitmap bits for clusters
*
* @check: Check structure
* @offset: Starting offset in bytes
* @n: Number of clusters
*/
static bool qed_set_used_clusters(QEDCheck *check, uint64_t offset,
unsigned int n)
{
uint64_t cluster = qed_bytes_to_clusters(check->s, offset);
unsigned int corruptions = 0;
while (n-- != 0) {
/* Clusters should only be referenced once */
if (qed_test_bit(check->used_clusters, cluster)) {
corruptions++;
}
qed_set_bit(check->used_clusters, cluster);
cluster++;
}
check->result->corruptions += corruptions;
return corruptions == 0;
}
/**
* Check an L2 table
*
* @ret: Number of invalid cluster offsets
*/
static unsigned int qed_check_l2_table(QEDCheck *check, QEDTable *table)
{
BDRVQEDState *s = check->s;
unsigned int i, num_invalid = 0;
for (i = 0; i < s->table_nelems; i++) {
uint64_t offset = table->offsets[i];
if (qed_offset_is_unalloc_cluster(offset) ||
qed_offset_is_zero_cluster(offset)) {
continue;
}
/* Detect invalid cluster offset */
if (!qed_check_cluster_offset(s, offset)) {
if (check->fix) {
table->offsets[i] = 0;
} else {
check->result->corruptions++;
}
num_invalid++;
continue;
}
qed_set_used_clusters(check, offset, 1);
}
return num_invalid;
}
/**
* Descend tables and check each cluster is referenced once only
*/
static int qed_check_l1_table(QEDCheck *check, QEDTable *table)
{
BDRVQEDState *s = check->s;
unsigned int i, num_invalid_l1 = 0;
int ret, last_error = 0;
/* Mark L1 table clusters used */
qed_set_used_clusters(check, s->header.l1_table_offset,
s->header.table_size);
for (i = 0; i < s->table_nelems; i++) {
unsigned int num_invalid_l2;
uint64_t offset = table->offsets[i];
if (qed_offset_is_unalloc_cluster(offset)) {
continue;
}
/* Detect invalid L2 offset */
if (!qed_check_table_offset(s, offset)) {
/* Clear invalid offset */
if (check->fix) {
table->offsets[i] = 0;
} else {
check->result->corruptions++;
}
num_invalid_l1++;
continue;
}
if (!qed_set_used_clusters(check, offset, s->header.table_size)) {
continue; /* skip an invalid table */
}
ret = qed_read_l2_table_sync(s, &check->request, offset);
if (ret) {
check->result->check_errors++;
last_error = ret;
continue;
}
num_invalid_l2 = qed_check_l2_table(check,
check->request.l2_table->table);
/* Write out fixed L2 table */
if (num_invalid_l2 > 0 && check->fix) {
ret = qed_write_l2_table_sync(s, &check->request, 0,
s->table_nelems, false);
if (ret) {
check->result->check_errors++;
last_error = ret;
continue;
}
}
}
/* Drop reference to final table */
qed_unref_l2_cache_entry(check->request.l2_table);
check->request.l2_table = NULL;
/* Write out fixed L1 table */
if (num_invalid_l1 > 0 && check->fix) {
ret = qed_write_l1_table_sync(s, 0, s->table_nelems);
if (ret) {
check->result->check_errors++;
last_error = ret;
}
}
return last_error;
}
/**
* Check for unreferenced (leaked) clusters
*/
static void qed_check_for_leaks(QEDCheck *check)
{
BDRVQEDState *s = check->s;
size_t i;
for (i = s->header.header_size; i < check->nclusters; i++) {
if (!qed_test_bit(check->used_clusters, i)) {
check->result->leaks++;
}
}
}
int qed_check(BDRVQEDState *s, BdrvCheckResult *result, bool fix)
{
QEDCheck check = {
.s = s,
.result = result,
.nclusters = qed_bytes_to_clusters(s, s->file_size),
.request = { .l2_table = NULL },
.fix = fix,
};
int ret;
check.used_clusters = qemu_mallocz(((check.nclusters + 31) / 32) *
sizeof(check.used_clusters[0]));
ret = qed_check_l1_table(&check, s->l1_table);
if (ret == 0) {
/* Only check for leaks if entire image was scanned successfully */
qed_check_for_leaks(&check);
}
qemu_free(check.used_clusters);
return ret;
}
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