qemu/block/qed-check.c
Markus Armbruster 02c4f26b15 block: Use g_new() & friends to avoid multiplying sizes
g_new(T, n) is safer than g_malloc(sizeof(*v) * n) for two reasons.
One, it catches multiplication overflowing size_t.  Two, it returns
T * rather than void *, which lets the compiler catch more type
errors.

Perhaps a conversion to g_malloc_n() would be neater in places, but
that's merely four years old, and we can't use such newfangled stuff.

This commit only touches allocations with size arguments of the form
sizeof(T), plus two that use 4 instead of sizeof(uint32_t).  We can
make the others safe by converting to g_malloc_n() when it becomes
available to us in a couple of years.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Jeff Cody <jcody@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2014-08-20 11:51:28 +02:00

251 lines
6.6 KiB
C

/*
* 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 */
uint64_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;
uint64_t last_offset = 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;
}
check->result->bfi.allocated_clusters++;
if (last_offset && (last_offset + s->header.cluster_size != offset)) {
check->result->bfi.fragmented_clusters++;
}
last_offset = offset;
/* Detect invalid cluster offset */
if (!qed_check_cluster_offset(s, offset)) {
if (check->fix) {
table->offsets[i] = 0;
check->result->corruptions_fixed++;
} 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;
check->result->corruptions_fixed++;
} 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;
uint64_t i;
for (i = s->header.header_size; i < check->nclusters; i++) {
if (!qed_test_bit(check->used_clusters, i)) {
check->result->leaks++;
}
}
}
/**
* Mark an image clean once it passes check or has been repaired
*/
static void qed_check_mark_clean(BDRVQEDState *s, BdrvCheckResult *result)
{
/* Skip if there were unfixable corruptions or I/O errors */
if (result->corruptions > 0 || result->check_errors > 0) {
return;
}
/* Skip if image is already marked clean */
if (!(s->header.features & QED_F_NEED_CHECK)) {
return;
}
/* Ensure fixes reach storage before clearing check bit */
bdrv_flush(s->bs);
s->header.features &= ~QED_F_NEED_CHECK;
qed_write_header_sync(s);
}
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 = g_try_new0(uint32_t, (check.nclusters + 31) / 32);
if (check.nclusters && check.used_clusters == NULL) {
return -ENOMEM;
}
check.result->bfi.total_clusters =
(s->header.image_size + s->header.cluster_size - 1) /
s->header.cluster_size;
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);
if (fix) {
qed_check_mark_clean(s, result);
}
}
g_free(check.used_clusters);
return ret;
}