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-rw-r--r--block/qed-check.c210
-rw-r--r--block/qed.c125
-rw-r--r--block/qed.h4
3 files changed, 336 insertions, 3 deletions
diff --git a/block/qed-check.c b/block/qed-check.c
new file mode 100644
index 0000000000..4600932bf2
--- /dev/null
+++ b/block/qed-check.c
@@ -0,0 +1,210 @@
+/*
+ * 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;
+}
diff --git a/block/qed.c b/block/qed.c
index 8e65d18424..085c4f2210 100644
--- a/block/qed.c
+++ b/block/qed.c
@@ -99,6 +99,81 @@ static int qed_write_header_sync(BDRVQEDState *s)
return 0;
}
+typedef struct {
+ GenericCB gencb;
+ BDRVQEDState *s;
+ struct iovec iov;
+ QEMUIOVector qiov;
+ int nsectors;
+ uint8_t *buf;
+} QEDWriteHeaderCB;
+
+static void qed_write_header_cb(void *opaque, int ret)
+{
+ QEDWriteHeaderCB *write_header_cb = opaque;
+
+ qemu_vfree(write_header_cb->buf);
+ gencb_complete(write_header_cb, ret);
+}
+
+static void qed_write_header_read_cb(void *opaque, int ret)
+{
+ QEDWriteHeaderCB *write_header_cb = opaque;
+ BDRVQEDState *s = write_header_cb->s;
+ BlockDriverAIOCB *acb;
+
+ if (ret) {
+ qed_write_header_cb(write_header_cb, ret);
+ return;
+ }
+
+ /* Update header */
+ qed_header_cpu_to_le(&s->header, (QEDHeader *)write_header_cb->buf);
+
+ acb = bdrv_aio_writev(s->bs->file, 0, &write_header_cb->qiov,
+ write_header_cb->nsectors, qed_write_header_cb,
+ write_header_cb);
+ if (!acb) {
+ qed_write_header_cb(write_header_cb, -EIO);
+ }
+}
+
+/**
+ * Update header in-place (does not rewrite backing filename or other strings)
+ *
+ * This function only updates known header fields in-place and does not affect
+ * extra data after the QED header.
+ */
+static void qed_write_header(BDRVQEDState *s, BlockDriverCompletionFunc cb,
+ void *opaque)
+{
+ /* We must write full sectors for O_DIRECT but cannot necessarily generate
+ * the data following the header if an unrecognized compat feature is
+ * active. Therefore, first read the sectors containing the header, update
+ * them, and write back.
+ */
+
+ BlockDriverAIOCB *acb;
+ int nsectors = (sizeof(QEDHeader) + BDRV_SECTOR_SIZE - 1) /
+ BDRV_SECTOR_SIZE;
+ size_t len = nsectors * BDRV_SECTOR_SIZE;
+ QEDWriteHeaderCB *write_header_cb = gencb_alloc(sizeof(*write_header_cb),
+ cb, opaque);
+
+ write_header_cb->s = s;
+ write_header_cb->nsectors = nsectors;
+ write_header_cb->buf = qemu_blockalign(s->bs, len);
+ write_header_cb->iov.iov_base = write_header_cb->buf;
+ write_header_cb->iov.iov_len = len;
+ qemu_iovec_init_external(&write_header_cb->qiov, &write_header_cb->iov, 1);
+
+ acb = bdrv_aio_readv(s->bs->file, 0, &write_header_cb->qiov, nsectors,
+ qed_write_header_read_cb, write_header_cb);
+ if (!acb) {
+ qed_write_header_cb(write_header_cb, -EIO);
+ }
+}
+
static uint64_t qed_max_image_size(uint32_t cluster_size, uint32_t table_size)
{
uint64_t table_entries;
@@ -310,6 +385,32 @@ static int bdrv_qed_open(BlockDriverState *bs, int flags)
ret = qed_read_l1_table_sync(s);
if (ret) {
+ goto out;
+ }
+
+ /* If image was not closed cleanly, check consistency */
+ if (s->header.features & QED_F_NEED_CHECK) {
+ /* Read-only images cannot be fixed. There is no risk of corruption
+ * since write operations are not possible. Therefore, allow
+ * potentially inconsistent images to be opened read-only. This can
+ * aid data recovery from an otherwise inconsistent image.
+ */
+ if (!bdrv_is_read_only(bs->file)) {
+ BdrvCheckResult result = {0};
+
+ ret = qed_check(s, &result, true);
+ if (!ret && !result.corruptions && !result.check_errors) {
+ /* Ensure fixes reach storage before clearing check bit */
+ bdrv_flush(s->bs);
+
+ s->header.features &= ~QED_F_NEED_CHECK;
+ qed_write_header_sync(s);
+ }
+ }
+ }
+
+out:
+ if (ret) {
qed_free_l2_cache(&s->l2_cache);
qemu_vfree(s->l1_table);
}
@@ -320,6 +421,15 @@ static void bdrv_qed_close(BlockDriverState *bs)
{
BDRVQEDState *s = bs->opaque;
+ /* Ensure writes reach stable storage */
+ bdrv_flush(bs->file);
+
+ /* Clean shutdown, no check required on next open */
+ if (s->header.features & QED_F_NEED_CHECK) {
+ s->header.features &= ~QED_F_NEED_CHECK;
+ qed_write_header_sync(s);
+ }
+
qed_free_l2_cache(&s->l2_cache);
qemu_vfree(s->l1_table);
}
@@ -885,8 +995,15 @@ static void qed_aio_write_alloc(QEDAIOCB *acb, size_t len)
acb->cur_cluster = qed_alloc_clusters(s, acb->cur_nclusters);
qemu_iovec_copy(&acb->cur_qiov, acb->qiov, acb->qiov_offset, len);
- /* Write new cluster */
- qed_aio_write_prefill(acb, 0);
+ /* Write new cluster if the image is already marked dirty */
+ if (s->header.features & QED_F_NEED_CHECK) {
+ qed_aio_write_prefill(acb, 0);
+ return;
+ }
+
+ /* Mark the image dirty before writing the new cluster */
+ s->header.features |= QED_F_NEED_CHECK;
+ qed_write_header(s, qed_aio_write_prefill, acb);
}
/**
@@ -1172,7 +1289,9 @@ static int bdrv_qed_change_backing_file(BlockDriverState *bs,
static int bdrv_qed_check(BlockDriverState *bs, BdrvCheckResult *result)
{
- return -ENOTSUP;
+ BDRVQEDState *s = bs->opaque;
+
+ return qed_check(s, result, false);
}
static QEMUOptionParameter qed_create_options[] = {
diff --git a/block/qed.h b/block/qed.h
index 046a4102c0..2925e37b1c 100644
--- a/block/qed.h
+++ b/block/qed.h
@@ -50,11 +50,15 @@ enum {
/* The image supports a backing file */
QED_F_BACKING_FILE = 0x01,
+ /* The image needs a consistency check before use */
+ QED_F_NEED_CHECK = 0x02,
+
/* The backing file format must not be probed, treat as raw image */
QED_F_BACKING_FORMAT_NO_PROBE = 0x04,
/* Feature bits must be used when the on-disk format changes */
QED_FEATURE_MASK = QED_F_BACKING_FILE | /* supported feature bits */
+ QED_F_NEED_CHECK |
QED_F_BACKING_FORMAT_NO_PROBE,
QED_COMPAT_FEATURE_MASK = 0, /* supported compat feature bits */
QED_AUTOCLEAR_FEATURE_MASK = 0, /* supported autoclear feature bits */
generated by cgit v1.2.1 (git 2.18.0) at 2024-06-13 17:59:55 +0000