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dirty-bitmap: Avoid size query failure during truncate

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We've previously fixed several places where we failed to account
for possible errors from bdrv_nb_sectors().  Fix another one by
making bdrv_dirty_bitmap_truncate() take the new size from the
caller instead of querying itself; then adjust the sole caller
bdrv_truncate() to pass the size just determined by a successful
resize, or to reuse the size given to the original truncate
operation when refresh_total_sectors() was not able to confirm the
actual size (the two sizes can potentially differ according to
rounding constraints), thus avoiding sizing the bitmaps to -1.
This also fixes a bug where not all failure paths in
bdrv_truncate() would set errp.

Note that bdrv_truncate() is still a bit awkward.  We may want
to revisit it later and clean up things to better guarantee that
a resize attempt either fails cleanly up front, or cannot fail
after guest-visible changes have been made (if temporary changes
are made, then they need to be cleanly rolled back).  But that
is a task for another day; for now, the goal is the bare minimum
fix to ensure that just bdrv_dirty_bitmap_truncate() cannot fail.

Signed-off-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: John Snow <jsnow@redhat.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Eric Blake 2017-09-25 09:55:11 -05:00 • committed by Kevin Wolf
parent dfe55c3577
commit 1b6cc579de
3 changed files with 15 additions and 9 deletions
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2
include/block/dirty-bitmap.h
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@ -83,7 +83,7 @@ int64_t bdrv_dirty_iter_next(BdrvDirtyBitmapIter *iter);
void bdrv_set_dirty_iter(BdrvDirtyBitmapIter *hbi, int64_t sector_num);
int64_t bdrv_get_dirty_count(BdrvDirtyBitmap *bitmap);
int64_t bdrv_get_meta_dirty_count(BdrvDirtyBitmap *bitmap);
void bdrv_dirty_bitmap_truncate(BlockDriverState *bs);
void bdrv_dirty_bitmap_truncate(BlockDriverState *bs, int64_t bytes);
bool bdrv_dirty_bitmap_readonly(const BdrvDirtyBitmap *bitmap);
bool bdrv_has_readonly_bitmaps(BlockDriverState *bs);
bool bdrv_dirty_bitmap_get_autoload(const BdrvDirtyBitmap *bitmap);