diff options
Diffstat (limited to 'block/qcow2.c')
| -rw-r--r-- | block/qcow2.c | 27 |
1 files changed, 27 insertions, 0 deletions
diff --git a/block/qcow2.c b/block/qcow2.c index d64a4bab3d..bf871d58f4 100644 --- a/block/qcow2.c +++ b/block/qcow2.c @@ -2230,6 +2230,32 @@ fail: return ret; } +static int qcow2_make_empty(BlockDriverState *bs) +{ + int ret = 0; + uint64_t start_sector; + int sector_step = INT_MAX / BDRV_SECTOR_SIZE; + + for (start_sector = 0; start_sector < bs->total_sectors; + start_sector += sector_step) + { + /* As this function is generally used after committing an external + * snapshot, QCOW2_DISCARD_SNAPSHOT seems appropriate. Also, the + * default action for this kind of discard is to pass the discard, + * which will ideally result in an actually smaller image file, as + * is probably desired. */ + ret = qcow2_discard_clusters(bs, start_sector * BDRV_SECTOR_SIZE, + MIN(sector_step, + bs->total_sectors - start_sector), + QCOW2_DISCARD_SNAPSHOT, true); + if (ret < 0) { + break; + } + } + + return ret; +} + static coroutine_fn int qcow2_co_flush_to_os(BlockDriverState *bs) { BDRVQcowState *s = bs->opaque; @@ -2676,6 +2702,7 @@ static BlockDriver bdrv_qcow2 = { .bdrv_co_discard = qcow2_co_discard, .bdrv_truncate = qcow2_truncate, .bdrv_write_compressed = qcow2_write_compressed, + .bdrv_make_empty = qcow2_make_empty, .bdrv_snapshot_create = qcow2_snapshot_create, .bdrv_snapshot_goto = qcow2_snapshot_goto, |