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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
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

16
block.c
View File

@ -3545,12 +3545,18 @@ int bdrv_truncate(BdrvChild *child, int64_t offset, PreallocMode prealloc,
assert(!(bs->open_flags & BDRV_O_INACTIVE));
ret = drv->bdrv_truncate(bs, offset, prealloc, errp);
if (ret == 0) {
ret = refresh_total_sectors(bs, offset >> BDRV_SECTOR_BITS);
bdrv_dirty_bitmap_truncate(bs);
bdrv_parent_cb_resize(bs);
atomic_inc(&bs->write_gen);
if (ret < 0) {
return ret;
}
ret = refresh_total_sectors(bs, offset >> BDRV_SECTOR_BITS);
if (ret < 0) {
error_setg_errno(errp, -ret, "Could not refresh total sector count");
} else {
offset = bs->total_sectors * BDRV_SECTOR_SIZE;
}
bdrv_dirty_bitmap_truncate(bs, offset);
bdrv_parent_cb_resize(bs);
atomic_inc(&bs->write_gen);
return ret;
}

6
block/dirty-bitmap.c
View File

@ -1,7 +1,7 @@
/*
* Block Dirty Bitmap
*
* Copyright (c) 2016 Red Hat. Inc
* Copyright (c) 2016-2017 Red Hat. Inc
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
@ -302,10 +302,10 @@ BdrvDirtyBitmap *bdrv_reclaim_dirty_bitmap(BlockDriverState *bs,
* Truncates _all_ bitmaps attached to a BDS.
* Called with BQL taken.
*/
void bdrv_dirty_bitmap_truncate(BlockDriverState *bs)
void bdrv_dirty_bitmap_truncate(BlockDriverState *bs, int64_t bytes)
{
BdrvDirtyBitmap *bitmap;
uint64_t size = bdrv_nb_sectors(bs);
int64_t size = DIV_ROUND_UP(bytes, BDRV_SECTOR_SIZE);
bdrv_dirty_bitmaps_lock(bs);
QLIST_FOREACH(bitmap, &bs->dirty_bitmaps, list) {

2
include/block/dirty-bitmap.h
View File

@ -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);