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-rw-r--r--block/file-posix.c4
1 files changed, 4 insertions, 0 deletions
diff --git a/block/file-posix.c b/block/file-posix.c
index 58326a0a60..bf09ad8bc0 100644
--- a/block/file-posix.c
+++ b/block/file-posix.c
@@ -702,6 +702,10 @@ static int raw_open_common(BlockDriverState *bs, QDict *options,
#endif
bs->supported_zero_flags = BDRV_REQ_MAY_UNMAP | BDRV_REQ_NO_FALLBACK;
+ if (S_ISREG(st.st_mode)) {
+ /* When extending regular files, we get zeros from the OS */
+ bs->supported_truncate_flags = BDRV_REQ_ZERO_WRITE;
+ }
ret = 0;
fail:
if (filename && (bdrv_flags & BDRV_O_TEMPORARY)) {