Skip to content

Commit

Permalink
qcow2: Employ metadata overlap checks
Browse files Browse the repository at this point in the history 
The pre-write overlap check function is now called before most of the
qcow2 writes (aborting it on collision or other error).

Signed-off-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
  • Loading branch information
@XanClic @kevmw
XanClic authored and kevmw committed Aug 30, 2013
1 parent a40f1c2 commit cf93980
Show file tree
Hide file tree
Showing 4 changed files with 86 additions and 0 deletions.
17 changes: 17 additions & 0 deletions block/qcow2-cache.c
View file
Expand Up @@ -114,6 +114,23 @@ static int qcow2_cache_entry_flush(BlockDriverState *bs, Qcow2Cache *c, int i)
return ret;
}

if (c == s->refcount_block_cache) {
ret = qcow2_pre_write_overlap_check(bs,
QCOW2_OL_DEFAULT & ~QCOW2_OL_REFCOUNT_BLOCK,
c->entries[i].offset, s->cluster_size);
} else if (c == s->l2_table_cache) {
ret = qcow2_pre_write_overlap_check(bs,
QCOW2_OL_DEFAULT & ~QCOW2_OL_ACTIVE_L2,
c->entries[i].offset, s->cluster_size);
} else {
ret = qcow2_pre_write_overlap_check(bs, QCOW2_OL_DEFAULT,
c->entries[i].offset, s->cluster_size);
}

if (ret < 0) {
return ret;
}

if (c == s->refcount_block_cache) {
BLKDBG_EVENT(bs->file, BLKDBG_REFBLOCK_UPDATE_PART);
} else if (c == s->l2_table_cache) {
Expand Down
21 changes: 21 additions & 0 deletions block/qcow2-cluster.c
View file
Expand Up @@ -80,6 +80,14 @@ int qcow2_grow_l1_table(BlockDriverState *bs, uint64_t min_size,
goto fail;
}

/* the L1 position has not yet been updated, so these clusters must
* indeed be completely free */
ret = qcow2_pre_write_overlap_check(bs, QCOW2_OL_DEFAULT,
new_l1_table_offset, new_l1_size2);
if (ret < 0) {
goto fail;
}

BLKDBG_EVENT(bs->file, BLKDBG_L1_GROW_WRITE_TABLE);
for(i = 0; i < s->l1_size; i++)
new_l1_table[i] = cpu_to_be64(new_l1_table[i]);
Expand Down Expand Up @@ -149,6 +157,13 @@ static int write_l1_entry(BlockDriverState *bs, int l1_index)
buf[i] = cpu_to_be64(s->l1_table[l1_start_index + i]);
}

ret = qcow2_pre_write_overlap_check(bs,
QCOW2_OL_DEFAULT & ~QCOW2_OL_ACTIVE_L1,
s->l1_table_offset + 8 * l1_start_index, sizeof(buf));
if (ret < 0) {
return ret;
}

BLKDBG_EVENT(bs->file, BLKDBG_L1_UPDATE);
ret = bdrv_pwrite_sync(bs->file, s->l1_table_offset + 8 * l1_start_index,
buf, sizeof(buf));
Expand Down Expand Up @@ -368,6 +383,12 @@ static int coroutine_fn copy_sectors(BlockDriverState *bs,
&s->aes_encrypt_key);
}

ret = qcow2_pre_write_overlap_check(bs, QCOW2_OL_DEFAULT,
cluster_offset + n_start * BDRV_SECTOR_SIZE, n * BDRV_SECTOR_SIZE);
if (ret < 0) {
goto out;
}

BLKDBG_EVENT(bs->file, BLKDBG_COW_WRITE);
ret = bdrv_co_writev(bs->file, (cluster_offset >> 9) + n_start, n, &qiov);
if (ret < 0) {
Expand Down
22 changes: 22 additions & 0 deletions block/qcow2-snapshot.c
View file
Expand Up @@ -189,6 +189,15 @@ static int qcow2_write_snapshots(BlockDriverState *bs)
return ret;
}

/* The snapshot list position has not yet been updated, so these clusters
* must indeed be completely free */
ret = qcow2_pre_write_overlap_check(bs, QCOW2_OL_DEFAULT, offset,
s->snapshots_size);
if (ret < 0) {
return ret;
}


/* Write all snapshots to the new list */
for(i = 0; i < s->nb_snapshots; i++) {
sn = s->snapshots + i;
Expand Down Expand Up @@ -363,6 +372,12 @@ int qcow2_snapshot_create(BlockDriverState *bs, QEMUSnapshotInfo *sn_info)
l1_table[i] = cpu_to_be64(s->l1_table[i]);
}

ret = qcow2_pre_write_overlap_check(bs, QCOW2_OL_DEFAULT,
sn->l1_table_offset, s->l1_size * sizeof(uint64_t));
if (ret < 0) {
goto fail;
}

ret = bdrv_pwrite(bs->file, sn->l1_table_offset, l1_table,
s->l1_size * sizeof(uint64_t));
if (ret < 0) {
Expand Down Expand Up @@ -475,6 +490,13 @@ int qcow2_snapshot_goto(BlockDriverState *bs, const char *snapshot_id)
goto fail;
}

ret = qcow2_pre_write_overlap_check(bs,
QCOW2_OL_DEFAULT & ~QCOW2_OL_ACTIVE_L1,
s->l1_table_offset, cur_l1_bytes);
if (ret < 0) {
goto fail;
}

ret = bdrv_pwrite_sync(bs->file, s->l1_table_offset, sn_l1_table,
cur_l1_bytes);
if (ret < 0) {
Expand Down
26 changes: 26 additions & 0 deletions block/qcow2.c
View file
Expand Up @@ -624,6 +624,8 @@ static int qcow2_open(BlockDriverState *bs, QDict *options, int flags)
qcow2_free_snapshots(bs);
qcow2_refcount_close(bs);
g_free(s->l1_table);
/* else pre-write overlap checks in cache_destroy may crash */
s->l1_table = NULL;
if (s->l2_table_cache) {
qcow2_cache_destroy(bs, s->l2_table_cache);
}
Expand Down Expand Up @@ -923,6 +925,13 @@ static coroutine_fn int qcow2_co_writev(BlockDriverState *bs,
cur_nr_sectors * 512);
}

ret = qcow2_pre_write_overlap_check(bs, QCOW2_OL_DEFAULT,
cluster_offset + index_in_cluster * BDRV_SECTOR_SIZE,
cur_nr_sectors * BDRV_SECTOR_SIZE);
if (ret < 0) {
goto fail;
}

qemu_co_mutex_unlock(&s->lock);
BLKDBG_EVENT(bs->file, BLKDBG_WRITE_AIO);
trace_qcow2_writev_data(qemu_coroutine_self(),
Expand Down Expand Up @@ -989,6 +998,8 @@ static void qcow2_close(BlockDriverState *bs)
{
BDRVQcowState *s = bs->opaque;
g_free(s->l1_table);
/* else pre-write overlap checks in cache_destroy may crash */
s->l1_table = NULL;

qcow2_cache_flush(bs, s->l2_table_cache);
qcow2_cache_flush(bs, s->refcount_block_cache);
Expand Down Expand Up @@ -1668,6 +1679,14 @@ static int qcow2_write_compressed(BlockDriverState *bs, int64_t sector_num,

if (ret != Z_STREAM_END || out_len >= s->cluster_size) {
/* could not compress: write normal cluster */

ret = qcow2_pre_write_overlap_check(bs, QCOW2_OL_DEFAULT,
sector_num * BDRV_SECTOR_SIZE,
s->cluster_sectors * BDRV_SECTOR_SIZE);
if (ret < 0) {
goto fail;
}

ret = bdrv_write(bs, sector_num, buf, s->cluster_sectors);
if (ret < 0) {
goto fail;
Expand All @@ -1680,6 +1699,13 @@ static int qcow2_write_compressed(BlockDriverState *bs, int64_t sector_num,
goto fail;
}
cluster_offset &= s->cluster_offset_mask;

ret = qcow2_pre_write_overlap_check(bs, QCOW2_OL_DEFAULT,
cluster_offset, out_len);
if (ret < 0) {
goto fail;
}

BLKDBG_EVENT(bs->file, BLKDBG_WRITE_COMPRESSED);
ret = bdrv_pwrite(bs->file, cluster_offset, out_buf, out_len);
if (ret < 0) {
Expand Down

0 comments on commit cf93980

Please sign in to comment.