[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
[Qemu-devel] [PATCH v5 02/12] qcow2: Implement bdrv_make_empty()
From: |
Max Reitz |
Subject: |
[Qemu-devel] [PATCH v5 02/12] qcow2: Implement bdrv_make_empty() |
Date: |
Thu, 17 Apr 2014 23:59:42 +0200 |
Implement bdrv_make_empty() by making all clusters in the image fall
through to the backing file (via the now modified discard).
Signed-off-by: Max Reitz <address@hidden>
---
block/qcow2.c | 22 ++++++++++++++++++++++
1 file changed, 22 insertions(+)
diff --git a/block/qcow2.c b/block/qcow2.c
index 1e7b7d5..4d70665 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -2006,6 +2006,27 @@ fail:
return ret;
}
+static int qcow2_make_empty(BlockDriverState *bs)
+{
+ uint64_t start_sector;
+ int ret = 0;
+
+ /* The step taken here may not exceed INT_MAX when multiplied by
+ * BDRV_SECTOR_SIZE. 64k is arbitrary, but works well. */
+ for (start_sector = 0; start_sector < bs->total_sectors;
+ start_sector += 65536)
+ {
+ ret = qcow2_discard_clusters(bs, start_sector * BDRV_SECTOR_SIZE,
+ MIN(65536, bs->total_sectors - start_sector),
+ QCOW2_DISCARD_REQUEST, true);
+ if (ret < 0) {
+ break;
+ }
+ }
+
+ return ret;
+}
+
static coroutine_fn int qcow2_co_flush_to_os(BlockDriverState *bs)
{
BDRVQcowState *s = bs->opaque;
@@ -2388,6 +2409,7 @@ 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,
--
1.9.2
- [Qemu-devel] [PATCH v5 09/12] qemu-img: Specify backing file for commit, (continued)