Add dirty bitmap extension as specified in docs/specs/qcow2.txt.
Load bitmap headers on open. Handle close and update_header.
Handle resize: for now, just block resize if there are dirty bitmaps.
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsement...@virtuozzo.com>
---
block/qcow2.c | 89 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 89 insertions(+)
diff --git a/block/qcow2.c b/block/qcow2.c
index 75ec4c0..6b6914d 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -61,6 +61,7 @@ typedef struct {
#define QCOW2_EXT_MAGIC_END 0
#define QCOW2_EXT_MAGIC_BACKING_FORMAT 0xE2792ACA
#define QCOW2_EXT_MAGIC_FEATURE_TABLE 0x6803f857
+#define QCOW2_EXT_MAGIC_DIRTY_BITMAPS 0x23852875
static int qcow2_probe(const uint8_t *buf, int buf_size, const char *filename)
{
@@ -90,6 +91,7 @@ static int qcow2_read_extensions(BlockDriverState *bs,
uint64_t start_offset,
QCowExtension ext;
uint64_t offset;
int ret;
+ Qcow2BitmapHeaderExt bitmaps_ext;
#ifdef DEBUG_EXT
printf("qcow2_read_extensions: start=%ld end=%ld\n", start_offset,
end_offset);
@@ -160,6 +162,67 @@ static int qcow2_read_extensions(BlockDriverState *bs,
uint64_t start_offset,
}
break;
+ case QCOW2_EXT_MAGIC_DIRTY_BITMAPS:
+ ret = bdrv_pread(bs->file->bs, offset, &bitmaps_ext, ext.len);
+ if (ret < 0) {
+ error_setg_errno(errp, -ret, "ERROR: bitmaps_ext: "
+ "Could not read ext header");
+ return ret;
+ }
+
+ if (bitmaps_ext.reserved32 != 0) {
+ error_setg_errno(errp, -ret, "ERROR: bitmaps_ext: "
+ "Reserved field is not zero.");
+ return -EINVAL;
+ }
+
+ be32_to_cpus(&bitmaps_ext.nb_bitmaps);
+ be64_to_cpus(&bitmaps_ext.bitmap_directory_size);
+ be64_to_cpus(&bitmaps_ext.bitmap_directory_offset);
+
+ if (bitmaps_ext.nb_bitmaps > QCOW_MAX_DIRTY_BITMAPS) {
+ error_setg(errp, "ERROR: bitmaps_ext: "
+ "too many dirty bitmaps");
+ return -EINVAL;
+ }
+
+ if (bitmaps_ext.nb_bitmaps == 0) {
+ error_setg(errp, "ERROR: bitmaps_ext: "
+ "found bitmaps extension with zero bitmaps");
+ return -EINVAL;
+ }
+
+ if (bitmaps_ext.bitmap_directory_offset & (s->cluster_size - 1)) {
+ error_setg(errp, "ERROR: bitmaps_ext: "
+ "wrong dirty bitmap directory offset");
+ return -EINVAL;
+ }
+
+ if (bitmaps_ext.bitmap_directory_size >
+ QCOW_MAX_DIRTY_BITMAP_DIRECTORY_SIZE) {
+ error_setg(errp, "ERROR: bitmaps_ext: "
+ "too large dirty bitmap directory");
+ return -EINVAL;
+ }
+
+ s->nb_bitmaps = bitmaps_ext.nb_bitmaps;
+ s->bitmap_directory_offset =
+ bitmaps_ext.bitmap_directory_offset;
+ s->bitmap_directory_size =
+ bitmaps_ext.bitmap_directory_size;
+
+ ret = qcow2_read_bitmaps(bs, errp);
+ if (ret < 0) {
+ return ret;
+ }
+
+#ifdef DEBUG_EXT
+ printf("Qcow2: Got dirty bitmaps extension:"
+ " offset=%" PRIu64 " nb_bitmaps=%" PRIu32 "\n",
+ s->bitmaps_offset, s->nb_bitmaps);
+#endif
+ break;
+
default:
/* unknown magic - save it in case we need to rewrite the header */
{
@@ -1177,6 +1240,7 @@ static int qcow2_open(BlockDriverState *bs, QDict
*options, int flags,
g_free(s->unknown_header_fields);
cleanup_unknown_header_ext(bs);
qcow2_free_snapshots(bs);
+ qcow2_free_bitmaps(bs);
qcow2_refcount_close(bs);
qemu_vfree(s->l1_table);
/* else pre-write overlap checks in cache_destroy may crash */
@@ -1740,6 +1804,7 @@ static void qcow2_close(BlockDriverState *bs)
qemu_vfree(s->cluster_data);
qcow2_refcount_close(bs);
qcow2_free_snapshots(bs);
+ qcow2_free_bitmaps(bs);
}
static void qcow2_invalidate_cache(BlockDriverState *bs, Error **errp)
@@ -1937,6 +2002,24 @@ int qcow2_update_header(BlockDriverState *bs)
buflen -= ret;
}
+ if (s->nb_bitmaps > 0) {
+ Qcow2BitmapHeaderExt bitmaps_header = {
+ .nb_bitmaps = cpu_to_be32(s->nb_bitmaps),
+ .bitmap_directory_size =
+ cpu_to_be64(s->bitmap_directory_size),
+ .bitmap_directory_offset =
+ cpu_to_be64(s->bitmap_directory_offset)
+ };
+ ret = header_ext_add(buf, QCOW2_EXT_MAGIC_DIRTY_BITMAPS,
+ &bitmaps_header, sizeof(bitmaps_header),
+ buflen);
+ if (ret < 0) {
+ goto fail;
+ }
+ buf += ret;
+ buflen -= ret;
+ }
+
/* Keep unknown header extensions */
QLIST_FOREACH(uext, &s->unknown_header_ext, next) {
ret = header_ext_add(buf, uext->magic, uext->data, uext->len, buflen);
@@ -2460,6 +2543,12 @@ static int qcow2_truncate(BlockDriverState *bs, int64_t
offset)
return -ENOTSUP;
}
+ /* cannot proceed if image has bitmaps */
+ if (s->nb_bitmaps) {
+ error_report("Can't resize an image which has dirty bitmaps");
+ return -ENOTSUP;
+ }
+
/* shrinking is currently not supported */
if (offset < bs->total_sectors * 512) {
error_report("qcow2 doesn't support shrinking images yet");
--
1.8.3.1
