/* * 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 (!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 (!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; }