commit 9ac228e02cf16202547e7025ef300369e0db7781
Author: Kevin Wolf <kwolf@redhat.com>
Date:   Tue Jun 29 12:37:54 2010 +0200

    qcow2/vdi: Change check to distinguish error cases
    
    This distinguishes between harmless leaks and real corruption. Hopefully users
    better understand what qemu-img check wants to tell them.
    
    Signed-off-by: Kevin Wolf <kwolf@redhat.com>

diff --git a/block/qcow2-refcount.c b/block/qcow2-refcount.c
index 4a96d98..4c19e7e 100644
--- a/block/qcow2-refcount.c
+++ b/block/qcow2-refcount.c
@@ -884,9 +884,10 @@ int qcow2_update_snapshot_refcount(BlockDriverState *bs,
  * This is used to construct a temporary refcount table out of L1 and L2 tables
  * which can be compared the the refcount table saved in the image.
  *
- * Returns the number of errors in the image that were found
+ * Modifies the number of errors in res.
  */
-static int inc_refcounts(BlockDriverState *bs,
+static void inc_refcounts(BlockDriverState *bs,
+                          BdrvCheckResult *res,
                           uint16_t *refcount_table,
                           int refcount_table_size,
                           int64_t offset, int64_t size)
@@ -894,30 +895,32 @@ static int inc_refcounts(BlockDriverState *bs,
     BDRVQcowState *s = bs->opaque;
     int64_t start, last, cluster_offset;
     int k;
-    int errors = 0;
 
     if (size <= 0)
-        return 0;
+        return;
 
     start = offset & ~(s->cluster_size - 1);
     last = (offset + size - 1) & ~(s->cluster_size - 1);
     for(cluster_offset = start; cluster_offset <= last;
         cluster_offset += s->cluster_size) {
         k = cluster_offset >> s->cluster_bits;
-        if (k < 0 || k >= refcount_table_size) {
+        if (k < 0) {
             fprintf(stderr, "ERROR: invalid cluster offset=0x%" PRIx64 "\n",
                 cluster_offset);
-            errors++;
+            res->corruptions++;
+        } else if (k >= refcount_table_size) {
+            fprintf(stderr, "Warning: cluster offset=0x%" PRIx64 " is after "
+                "the end of the image file, can't properly check refcounts.\n",
+                cluster_offset);
+            res->check_errors++;
         } else {
             if (++refcount_table[k] == 0) {
                 fprintf(stderr, "ERROR: overflow cluster offset=0x%" PRIx64
                     "\n", cluster_offset);
-                errors++;
+                res->corruptions++;
             }
         }
     }
-
-    return errors;
 }
 
 /*
@@ -928,14 +931,13 @@ static int inc_refcounts(BlockDriverState *bs,
  * Returns the number of errors found by the checks or -errno if an internal
  * error occurred.
  */
-static int check_refcounts_l2(BlockDriverState *bs,
+static int check_refcounts_l2(BlockDriverState *bs, BdrvCheckResult *res,
     uint16_t *refcount_table, int refcount_table_size, int64_t l2_offset,
     int check_copied)
 {
     BDRVQcowState *s = bs->opaque;
     uint64_t *l2_table, offset;
     int i, l2_size, nb_csectors, refcount;
-    int errors = 0;
 
     /* Read L2 table from disk */
     l2_size = s->l2_size * sizeof(uint64_t);
@@ -955,16 +957,15 @@ static int check_refcounts_l2(BlockDriverState *bs,
                         "copied flag must never be set for compressed "
                         "clusters\n", offset >> s->cluster_bits);
                     offset &= ~QCOW_OFLAG_COPIED;
-                    errors++;
+                    res->corruptions++;
                 }
 
                 /* Mark cluster as used */
                 nb_csectors = ((offset >> s->csize_shift) &
                                s->csize_mask) + 1;
                 offset &= s->cluster_offset_mask;
-                errors += inc_refcounts(bs, refcount_table,
-                              refcount_table_size,
-                              offset & ~511, nb_csectors * 512);
+                inc_refcounts(bs, res, refcount_table, refcount_table_size,
+                    offset & ~511, nb_csectors * 512);
             } else {
                 /* QCOW_OFLAG_COPIED must be set iff refcount == 1 */
                 if (check_copied) {
@@ -974,35 +975,35 @@ static int check_refcounts_l2(BlockDriverState *bs,
                     if (refcount < 0) {
                         fprintf(stderr, "Can't get refcount for offset %"
                             PRIx64 ": %s\n", entry, strerror(-refcount));
+                        goto fail;
                     }
                     if ((refcount == 1) != ((entry & QCOW_OFLAG_COPIED) != 0)) {
                         fprintf(stderr, "ERROR OFLAG_COPIED: offset=%"
                             PRIx64 " refcount=%d\n", entry, refcount);
-                        errors++;
+                        res->corruptions++;
                     }
                 }
 
                 /* Mark cluster as used */
                 offset &= ~QCOW_OFLAG_COPIED;
-                errors += inc_refcounts(bs, refcount_table,
-                              refcount_table_size,
-                              offset, s->cluster_size);
+                inc_refcounts(bs, res, refcount_table,refcount_table_size,
+                    offset, s->cluster_size);
 
                 /* Correct offsets are cluster aligned */
                 if (offset & (s->cluster_size - 1)) {
                     fprintf(stderr, "ERROR offset=%" PRIx64 ": Cluster is not "
                         "properly aligned; L2 entry corrupted.\n", offset);
-                    errors++;
+                    res->corruptions++;
                 }
             }
         }
     }
 
     qemu_free(l2_table);
-    return errors;
+    return 0;
 
 fail:
-    fprintf(stderr, "ERROR: I/O error in check_refcounts_l1\n");
+    fprintf(stderr, "ERROR: I/O error in check_refcounts_l2\n");
     qemu_free(l2_table);
     return -EIO;
 }
@@ -1016,6 +1017,7 @@ fail:
  * error occurred.
  */
 static int check_refcounts_l1(BlockDriverState *bs,
+                              BdrvCheckResult *res,
                               uint16_t *refcount_table,
                               int refcount_table_size,
                               int64_t l1_table_offset, int l1_size,
@@ -1024,13 +1026,12 @@ static int check_refcounts_l1(BlockDriverState *bs,
     BDRVQcowState *s = bs->opaque;
     uint64_t *l1_table, l2_offset, l1_size2;
     int i, refcount, ret;
-    int errors = 0;
 
     l1_size2 = l1_size * sizeof(uint64_t);
 
     /* Mark L1 table as used */
-    errors += inc_refcounts(bs, refcount_table, refcount_table_size,
-                  l1_table_offset, l1_size2);
+    inc_refcounts(bs, res, refcount_table, refcount_table_size,
+        l1_table_offset, l1_size2);
 
     /* Read L1 table entries from disk */
     if (l1_size2 == 0) {
@@ -1055,42 +1056,41 @@ static int check_refcounts_l1(BlockDriverState *bs,
                 if (refcount < 0) {
                     fprintf(stderr, "Can't get refcount for l2_offset %"
                         PRIx64 ": %s\n", l2_offset, strerror(-refcount));
+                    goto fail;
                 }
                 if ((refcount == 1) != ((l2_offset & QCOW_OFLAG_COPIED) != 0)) {
                     fprintf(stderr, "ERROR OFLAG_COPIED: l2_offset=%" PRIx64
                         " refcount=%d\n", l2_offset, refcount);
-                    errors++;
+                    res->corruptions++;
                 }
             }
 
             /* Mark L2 table as used */
             l2_offset &= ~QCOW_OFLAG_COPIED;
-            errors += inc_refcounts(bs, refcount_table,
-                          refcount_table_size,
-                          l2_offset,
-                          s->cluster_size);
+            inc_refcounts(bs, res, refcount_table, refcount_table_size,
+                l2_offset, s->cluster_size);
 
             /* L2 tables are cluster aligned */
             if (l2_offset & (s->cluster_size - 1)) {
                 fprintf(stderr, "ERROR l2_offset=%" PRIx64 ": Table is not "
                     "cluster aligned; L1 entry corrupted\n", l2_offset);
-                errors++;
+                res->corruptions++;
             }
 
             /* Process and check L2 entries */
-            ret = check_refcounts_l2(bs, refcount_table, refcount_table_size,
-                l2_offset, check_copied);
+            ret = check_refcounts_l2(bs, res, refcount_table,
+                refcount_table_size, l2_offset, check_copied);
             if (ret < 0) {
                 goto fail;
             }
-            errors += ret;
         }
     }
     qemu_free(l1_table);
-    return errors;
+    return 0;
 
 fail:
     fprintf(stderr, "ERROR: I/O error in check_refcounts_l1\n");
+    res->check_errors++;
     qemu_free(l1_table);
     return -EIO;
 }
@@ -1101,44 +1101,47 @@ fail:
  * Returns 0 if no errors are found, the number of errors in case the image is
  * detected as corrupted, and -errno when an internal error occured.
  */
-int qcow2_check_refcounts(BlockDriverState *bs)
+int qcow2_check_refcounts(BlockDriverState *bs, BdrvCheckResult *res)
 {
     BDRVQcowState *s = bs->opaque;
     int64_t size;
     int nb_clusters, refcount1, refcount2, i;
     QCowSnapshot *sn;
     uint16_t *refcount_table;
-    int ret, errors = 0;
+    int ret;
 
     size = bdrv_getlength(bs->file);
     nb_clusters = size_to_clusters(s, size);
     refcount_table = qemu_mallocz(nb_clusters * sizeof(uint16_t));
 
     /* header */
-    errors += inc_refcounts(bs, refcount_table, nb_clusters,
-                  0, s->cluster_size);
+    inc_refcounts(bs, res, refcount_table, nb_clusters,
+        0, s->cluster_size);
 
     /* current L1 table */
-    ret = check_refcounts_l1(bs, refcount_table, nb_clusters,
+    ret = check_refcounts_l1(bs, res, refcount_table, nb_clusters,
                        s->l1_table_offset, s->l1_size, 1);
     if (ret < 0) {
         return ret;
     }
-    errors += ret;
 
     /* snapshots */
     for(i = 0; i < s->nb_snapshots; i++) {
         sn = s->snapshots + i;
-        check_refcounts_l1(bs, refcount_table, nb_clusters,
-                           sn->l1_table_offset, sn->l1_size, 0);
+        ret = check_refcounts_l1(bs, res, refcount_table, nb_clusters,
+            sn->l1_table_offset, sn->l1_size, 0);
+        if (ret < 0) {
+            return ret;
+        }
     }
-    errors += inc_refcounts(bs, refcount_table, nb_clusters,
-                  s->snapshots_offset, s->snapshots_size);
+    inc_refcounts(bs, res, refcount_table, nb_clusters,
+        s->snapshots_offset, s->snapshots_size);
 
     /* refcount data */
-    errors += inc_refcounts(bs, refcount_table, nb_clusters,
-                  s->refcount_table_offset,
-                  s->refcount_table_size * sizeof(uint64_t));
+    inc_refcounts(bs, res, refcount_table, nb_clusters,
+        s->refcount_table_offset,
+        s->refcount_table_size * sizeof(uint64_t));
+
     for(i = 0; i < s->refcount_table_size; i++) {
         uint64_t offset, cluster;
         offset = s->refcount_table[i];
@@ -1148,22 +1151,23 @@ int qcow2_check_refcounts(BlockDriverState *bs)
         if (offset & (s->cluster_size - 1)) {
             fprintf(stderr, "ERROR refcount block %d is not "
                 "cluster aligned; refcount table entry corrupted\n", i);
-            errors++;
+            res->corruptions++;
             continue;
         }
 
         if (cluster >= nb_clusters) {
             fprintf(stderr, "ERROR refcount block %d is outside image\n", i);
-            errors++;
+            res->corruptions++;
             continue;
         }
 
         if (offset != 0) {
-            errors += inc_refcounts(bs, refcount_table, nb_clusters,
-                          offset, s->cluster_size);
+            inc_refcounts(bs, res, refcount_table, nb_clusters,
+                offset, s->cluster_size);
             if (refcount_table[cluster] != 1) {
                 fprintf(stderr, "ERROR refcount block %d refcount=%d\n",
                     i, refcount_table[cluster]);
+                res->corruptions++;
             }
         }
     }
@@ -1174,19 +1178,25 @@ int qcow2_check_refcounts(BlockDriverState *bs)
         if (refcount1 < 0) {
             fprintf(stderr, "Can't get refcount for cluster %d: %s\n",
                 i, strerror(-refcount1));
+            res->check_errors++;
             continue;
         }
 
         refcount2 = refcount_table[i];
         if (refcount1 != refcount2) {
-            fprintf(stderr, "ERROR cluster %d refcount=%d reference=%d\n",
+            fprintf(stderr, "%s cluster %d refcount=%d reference=%d\n",
+                   refcount1 < refcount2 ? "ERROR" : "Leaked",
                    i, refcount1, refcount2);
-            errors++;
+            if (refcount1 < refcount2) {
+                res->corruptions++;
+            } else {
+                res->leaks++;
+            }
         }
     }
 
     qemu_free(refcount_table);
 
-    return errors;
+    return 0;
 }
 
