block/dirty-bitmaps: implement inconsistent bit
Set the inconsistent bit on load instead of rejecting such bitmaps.
There is no way to un-set it; the only option is to delete the bitmap.
Obvervations:
- bitmap loading does not need to update the header for in_use bitmaps.
- inconsistent bitmaps don't need to have their data loaded; they're
glorified corruption sentinels.
- bitmap saving does not need to save inconsistent bitmaps back to disk.
- bitmap reopening DOES need to drop the readonly flag from inconsistent
bitmaps to allow reopening of qcow2 files with non-qemu-owned bitmaps
being eventually flushed back to disk.
Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-id: 20190301191545.8728-8-jsnow@redhat.com
Signed-off-by: John Snow <jsnow@redhat.com>
diff --git a/block/qcow2-bitmap.c b/block/qcow2-bitmap.c
index 9d968bd..2c3e088 100644
--- a/block/qcow2-bitmap.c
+++ b/block/qcow2-bitmap.c
@@ -343,11 +343,17 @@
uint32_t granularity;
BdrvDirtyBitmap *bitmap = NULL;
- if (bm->flags & BME_FLAG_IN_USE) {
- error_setg(errp, "Bitmap '%s' is in use", bm->name);
+ granularity = 1U << bm->granularity_bits;
+ bitmap = bdrv_create_dirty_bitmap(bs, granularity, bm->name, errp);
+ if (bitmap == NULL) {
goto fail;
}
+ if (bm->flags & BME_FLAG_IN_USE) {
+ /* Data is unusable, skip loading it */
+ return bitmap;
+ }
+
ret = bitmap_table_load(bs, &bm->table, &bitmap_table);
if (ret < 0) {
error_setg_errno(errp, -ret,
@@ -356,12 +362,6 @@
goto fail;
}
- granularity = 1U << bm->granularity_bits;
- bitmap = bdrv_create_dirty_bitmap(bs, granularity, bm->name, errp);
- if (bitmap == NULL) {
- goto fail;
- }
-
ret = load_bitmap_data(bs, bitmap_table, bm->table.size, bitmap);
if (ret < 0) {
error_setg_errno(errp, -ret, "Could not read bitmap '%s' from image",
@@ -950,6 +950,7 @@
Qcow2Bitmap *bm;
GSList *created_dirty_bitmaps = NULL;
bool header_updated = false;
+ bool needs_update = false;
if (s->nb_bitmaps == 0) {
/* No bitmaps - nothing to do */
@@ -963,35 +964,39 @@
}
QSIMPLEQ_FOREACH(bm, bm_list, entry) {
- if (!(bm->flags & BME_FLAG_IN_USE)) {
- BdrvDirtyBitmap *bitmap = load_bitmap(bs, bm, errp);
- if (bitmap == NULL) {
- goto fail;
- }
-
- if (!(bm->flags & BME_FLAG_AUTO)) {
- bdrv_disable_dirty_bitmap(bitmap);
- }
- bdrv_dirty_bitmap_set_persistance(bitmap, true);
- bm->flags |= BME_FLAG_IN_USE;
- created_dirty_bitmaps =
- g_slist_append(created_dirty_bitmaps, bitmap);
+ BdrvDirtyBitmap *bitmap = load_bitmap(bs, bm, errp);
+ if (bitmap == NULL) {
+ goto fail;
}
+
+ bdrv_dirty_bitmap_set_persistance(bitmap, true);
+ if (bm->flags & BME_FLAG_IN_USE) {
+ bdrv_dirty_bitmap_set_inconsistent(bitmap);
+ } else {
+ /* NB: updated flags only get written if can_write(bs) is true. */
+ bm->flags |= BME_FLAG_IN_USE;
+ needs_update = true;
+ }
+ if (!(bm->flags & BME_FLAG_AUTO)) {
+ bdrv_disable_dirty_bitmap(bitmap);
+ }
+ created_dirty_bitmaps =
+ g_slist_append(created_dirty_bitmaps, bitmap);
}
- if (created_dirty_bitmaps != NULL) {
- if (can_write(bs)) {
- /* in_use flags must be updated */
- int ret = update_ext_header_and_dir_in_place(bs, bm_list);
- if (ret < 0) {
- error_setg_errno(errp, -ret, "Can't update bitmap directory");
- goto fail;
- }
- header_updated = true;
- } else {
- g_slist_foreach(created_dirty_bitmaps, set_readonly_helper,
- (gpointer)true);
+ if (needs_update && can_write(bs)) {
+ /* in_use flags must be updated */
+ int ret = update_ext_header_and_dir_in_place(bs, bm_list);
+ if (ret < 0) {
+ error_setg_errno(errp, -ret, "Can't update bitmap directory");
+ goto fail;
}
+ header_updated = true;
+ }
+
+ if (!can_write(bs)) {
+ g_slist_foreach(created_dirty_bitmaps, set_readonly_helper,
+ (gpointer)true);
}
g_slist_free(created_dirty_bitmaps);
@@ -1113,23 +1118,21 @@
}
QSIMPLEQ_FOREACH(bm, bm_list, entry) {
- if (!(bm->flags & BME_FLAG_IN_USE)) {
- BdrvDirtyBitmap *bitmap = bdrv_find_dirty_bitmap(bs, bm->name);
- if (bitmap == NULL) {
- continue;
- }
-
- if (!bdrv_dirty_bitmap_readonly(bitmap)) {
- error_setg(errp, "Bitmap %s is not readonly but not marked"
- "'IN_USE' in the image. Something went wrong,"
- "all the bitmaps may be corrupted", bm->name);
- ret = -EINVAL;
- goto out;
- }
-
- bm->flags |= BME_FLAG_IN_USE;
- ro_dirty_bitmaps = g_slist_append(ro_dirty_bitmaps, bitmap);
+ BdrvDirtyBitmap *bitmap = bdrv_find_dirty_bitmap(bs, bm->name);
+ if (bitmap == NULL) {
+ continue;
}
+
+ if (!bdrv_dirty_bitmap_readonly(bitmap)) {
+ error_setg(errp, "Bitmap %s was loaded prior to rw-reopen, but was "
+ "not marked as readonly. This is a bug, something went "
+ "wrong. All of the bitmaps may be corrupted", bm->name);
+ ret = -EINVAL;
+ goto out;
+ }
+
+ bm->flags |= BME_FLAG_IN_USE;
+ ro_dirty_bitmaps = g_slist_append(ro_dirty_bitmaps, bitmap);
}
if (ro_dirty_bitmaps != NULL) {
@@ -1425,8 +1428,8 @@
Qcow2Bitmap *bm;
if (!bdrv_dirty_bitmap_get_persistance(bitmap) ||
- bdrv_dirty_bitmap_readonly(bitmap))
- {
+ bdrv_dirty_bitmap_readonly(bitmap) ||
+ bdrv_dirty_bitmap_inconsistent(bitmap)) {
continue;
}
