From b7661ca5d84a7d330acc3c3f471e757e55261f84 Mon Sep 17 00:00:00 2001 From: John Snow Date: Mon, 29 Jul 2019 16:35:53 -0400 Subject: block/dirty-bitmap: add bdrv_dirty_bitmap_merge_internal I'm surprised it didn't come up sooner, but sometimes we have a +busy bitmap as a source. This is dangerous from the QMP API, but if we are the owner that marked the bitmap busy, it's safe to merge it using it as a read only source. It is not safe in the general case to allow users to read from in-use bitmaps, so create an internal variant that foregoes the safety checking. Signed-off-by: John Snow Reviewed-by: Max Reitz Message-id: 20190709232550.10724-10-jsnow@redhat.com Signed-off-by: John Snow --- block/dirty-bitmap.c | 54 +++++++++++++++++++++++++++++++++++++++++++++++----- 1 file changed, 49 insertions(+), 5 deletions(-) (limited to 'block') diff --git a/block/dirty-bitmap.c b/block/dirty-bitmap.c index 95a9c2a..7881fea 100644 --- a/block/dirty-bitmap.c +++ b/block/dirty-bitmap.c @@ -810,6 +810,12 @@ bool bdrv_dirty_bitmap_next_dirty_area(BdrvDirtyBitmap *bitmap, return hbitmap_next_dirty_area(bitmap->bitmap, offset, bytes); } +/** + * bdrv_merge_dirty_bitmap: merge src into dest. + * Ensures permissions on bitmaps are reasonable; use for public API. + * + * @backup: If provided, make a copy of dest here prior to merge. + */ void bdrv_merge_dirty_bitmap(BdrvDirtyBitmap *dest, const BdrvDirtyBitmap *src, HBitmap **backup, Error **errp) { @@ -833,6 +839,42 @@ void bdrv_merge_dirty_bitmap(BdrvDirtyBitmap *dest, const BdrvDirtyBitmap *src, goto out; } + ret = bdrv_dirty_bitmap_merge_internal(dest, src, backup, false); + assert(ret); + +out: + qemu_mutex_unlock(dest->mutex); + if (src->mutex != dest->mutex) { + qemu_mutex_unlock(src->mutex); + } +} + +/** + * bdrv_dirty_bitmap_merge_internal: merge src into dest. + * Does NOT check bitmap permissions; not suitable for use as public API. + * + * @backup: If provided, make a copy of dest here prior to merge. + * @lock: If true, lock and unlock bitmaps on the way in/out. + * returns true if the merge succeeded; false if unattempted. + */ +bool bdrv_dirty_bitmap_merge_internal(BdrvDirtyBitmap *dest, + const BdrvDirtyBitmap *src, + HBitmap **backup, + bool lock) +{ + bool ret; + + assert(!bdrv_dirty_bitmap_readonly(dest)); + assert(!bdrv_dirty_bitmap_inconsistent(dest)); + assert(!bdrv_dirty_bitmap_inconsistent(src)); + + if (lock) { + qemu_mutex_lock(dest->mutex); + if (src->mutex != dest->mutex) { + qemu_mutex_lock(src->mutex); + } + } + if (backup) { *backup = dest->bitmap; dest->bitmap = hbitmap_alloc(dest->size, hbitmap_granularity(*backup)); @@ -840,11 +882,13 @@ void bdrv_merge_dirty_bitmap(BdrvDirtyBitmap *dest, const BdrvDirtyBitmap *src, } else { ret = hbitmap_merge(dest->bitmap, src->bitmap, dest->bitmap); } - assert(ret); -out: - qemu_mutex_unlock(dest->mutex); - if (src->mutex != dest->mutex) { - qemu_mutex_unlock(src->mutex); + if (lock) { + qemu_mutex_unlock(dest->mutex); + if (src->mutex != dest->mutex) { + qemu_mutex_unlock(src->mutex); + } } + + return ret; } -- cgit v1.1