diff options
Diffstat (limited to 'qemu/block/qed-check.c')
| -rw-r--r-- | qemu/block/qed-check.c | 250 |
1 files changed, 250 insertions, 0 deletions
diff --git a/qemu/block/qed-check.c b/qemu/block/qed-check.c new file mode 100644 index 000000000..36ecd290d --- /dev/null +++ b/qemu/block/qed-check.c @@ -0,0 +1,250 @@ +/* + * 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; +} |