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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>
This commit is contained in:
John Snow 2019-03-12 12:05:49 -04:00
parent cb8e58e3de
commit 74da6b9435
1 changed files with 54 additions and 51 deletions
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105
block/qcow2-bitmap.c
View File

@ -343,11 +343,17 @@ static BdrvDirtyBitmap *load_bitmap(BlockDriverState *bs,
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 @@ static BdrvDirtyBitmap *load_bitmap(BlockDriverState *bs,
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 @@ bool qcow2_load_dirty_bitmaps(BlockDriverState *bs, Error **errp)
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 @@ bool qcow2_load_dirty_bitmaps(BlockDriverState *bs, Error **errp)
}
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 @@ int qcow2_reopen_bitmaps_rw_hint(BlockDriverState *bs, bool *header_updated,
}
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 @@ void qcow2_store_persistent_dirty_bitmaps(BlockDriverState *bs, Error **errp)
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;
}