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qcow2: Refcount checking code cleanup (Kevin Wolf)

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This is purely cosmetical changes to make the code easier to read. Move L2
table processing from a deeply nested block to its own function, add some
comments.

Patch v2: Fix misplaced bracket causing false positives

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>


git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@7216 c046a42c-6fe2-441c-8c8c-71466251a162
This commit is contained in:
aliguori 2009-04-21 23:11:58 +00:00
parent 1585969c6e
commit ae2f14af54
1 changed files with 105 additions and 44 deletions
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149
block-qcow2.c
View file

@ -2603,6 +2603,90 @@ static int inc_refcounts(BlockDriverState *bs,
return errors;
}
/*
* Increases the refcount in the given refcount table for the all clusters
* referenced in the L2 table. While doing so, performs some checks on L2
* entries.
*
* Returns the number of errors found by the checks or -errno if an internal
* error occurred.
*/
static int check_refcounts_l2(BlockDriverState *bs,
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);
l2_table = qemu_malloc(l2_size);
if (bdrv_pread(s->hd, l2_offset, l2_table, l2_size) != l2_size)
goto fail;
/* Do the actual checks */
for(i = 0; i < s->l2_size; i++) {
offset = be64_to_cpu(l2_table[i]);
if (offset != 0) {
if (offset & QCOW_OFLAG_COMPRESSED) {
/* Compressed clusters don't have QCOW_OFLAG_COPIED */
if (offset & QCOW_OFLAG_COPIED) {
fprintf(stderr, "ERROR: cluster %" PRId64 ": "
"copied flag must never be set for compressed "
"clusters\n", offset >> s->cluster_bits);
offset &= ~QCOW_OFLAG_COPIED;
errors++;
}
/* 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);
} else {
/* QCOW_OFLAG_COPIED must be set iff refcount == 1 */
if (check_copied) {
uint64_t entry = offset;
offset &= ~QCOW_OFLAG_COPIED;
refcount = get_refcount(bs, offset >> s->cluster_bits);
if ((refcount == 1) != ((entry & QCOW_OFLAG_COPIED) != 0)) {
fprintf(stderr, "ERROR OFLAG_COPIED: offset=%"
PRIx64 " refcount=%d\n", entry, refcount);
errors++;
}
}
/* Mark cluster as used */
offset &= ~QCOW_OFLAG_COPIED;
errors += inc_refcounts(bs, refcount_table,
refcount_table_size,
offset, s->cluster_size);
}
}
}
qemu_free(l2_table);
return errors;
fail:
fprintf(stderr, "ERROR: I/O error in check_refcounts_l1\n");
qemu_free(l2_table);
return -EIO;
}
/*
* Increases the refcount for the L1 table, its L2 tables and all referenced
* clusters in the given refcount table. While doing so, performs some checks
* on L1 and L2 entries.
*
* Returns the number of errors found by the checks or -errno if an internal
* error occurred.
*/
static int check_refcounts_l1(BlockDriverState *bs,
uint16_t *refcount_table,
int refcount_table_size,
@ -2610,16 +2694,17 @@ static int check_refcounts_l1(BlockDriverState *bs,
int check_copied)
{
BDRVQcowState *s = bs->opaque;
uint64_t *l1_table, *l2_table, l2_offset, offset, l1_size2;
int l2_size, i, j, nb_csectors, refcount;
uint64_t *l1_table, l2_offset, l1_size2;
int i, refcount, ret;
int errors = 0;
l2_table = NULL;
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);
/* Read L1 table entries from disk */
l1_table = qemu_malloc(l1_size2);
if (bdrv_pread(s->hd, l1_table_offset,
l1_table, l1_size2) != l1_size2)
@ -2627,68 +2712,43 @@ static int check_refcounts_l1(BlockDriverState *bs,
for(i = 0;i < l1_size; i++)
be64_to_cpus(&l1_table[i]);
l2_size = s->l2_size * sizeof(uint64_t);
l2_table = qemu_malloc(l2_size);
/* Do the actual checks */
for(i = 0; i < l1_size; i++) {
l2_offset = l1_table[i];
if (l2_offset) {
/* QCOW_OFLAG_COPIED must be set iff refcount == 1 */
if (check_copied) {
refcount = get_refcount(bs, (l2_offset & ~QCOW_OFLAG_COPIED) >> s->cluster_bits);
refcount = get_refcount(bs, (l2_offset & ~QCOW_OFLAG_COPIED)
>> s->cluster_bits);
if ((refcount == 1) != ((l2_offset & QCOW_OFLAG_COPIED) != 0)) {
fprintf(stderr, "ERROR OFLAG_COPIED: l2_offset=%" PRIx64
" refcount=%d\n", l2_offset, refcount);
errors++;
}
}
/* Mark L2 table as used */
l2_offset &= ~QCOW_OFLAG_COPIED;
if (bdrv_pread(s->hd, l2_offset, l2_table, l2_size) != l2_size)
goto fail;
for(j = 0; j < s->l2_size; j++) {
offset = be64_to_cpu(l2_table[j]);
if (offset != 0) {
if (offset & QCOW_OFLAG_COMPRESSED) {
if (offset & QCOW_OFLAG_COPIED) {
fprintf(stderr, "ERROR: cluster %" PRId64 ": "
"copied flag must never be set for compressed "
"clusters\n", offset >> s->cluster_bits);
offset &= ~QCOW_OFLAG_COPIED;
errors++;
}
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);
} else {
if (check_copied) {
refcount = get_refcount(bs, (offset & ~QCOW_OFLAG_COPIED) >> s->cluster_bits);
if ((refcount == 1) != ((offset & QCOW_OFLAG_COPIED) != 0)) {
fprintf(stderr, "ERROR OFLAG_COPIED: offset=%"
PRIx64 " refcount=%d\n", offset, refcount);
errors++;
}
}
offset &= ~QCOW_OFLAG_COPIED;
errors += inc_refcounts(bs, refcount_table,
refcount_table_size,
offset, s->cluster_size);
}
}
}
errors += inc_refcounts(bs, refcount_table,
refcount_table_size,
l2_offset,
s->cluster_size);
/* Process and check L2 entries */
ret = check_refcounts_l2(bs, refcount_table, refcount_table_size,
l2_offset, check_copied);
if (ret < 0) {
goto fail;
}
errors += ret;
}
}
qemu_free(l1_table);
qemu_free(l2_table);
return errors;
fail:
fail:
fprintf(stderr, "ERROR: I/O error in check_refcounts_l1\n");
qemu_free(l1_table);
qemu_free(l2_table);
return -EIO;
}
@ -2715,6 +2775,7 @@ static int check_refcounts(BlockDriverState *bs)
errors += inc_refcounts(bs, refcount_table, nb_clusters,
0, s->cluster_size);
/* current L1 table */
ret = check_refcounts_l1(bs, refcount_table, nb_clusters,
s->l1_table_offset, s->l1_size, 1);
if (ret < 0) {