diff mbox series

[v4,6/9] file-posix: Support BDRV_REQ_ZERO_WRITE for truncate

Message ID 20200420133214.28921-7-kwolf@redhat.com
State New
Headers show
Series [v4,1/9] block: Add flags to BlockDriver.bdrv_co_truncate() | expand

Commit Message

Kevin Wolf April 20, 2020, 1:32 p.m. UTC 
For regular files, we always get BDRV_REQ_ZERO_WRITE behaviour from the
OS, so we can advertise the flag and just ignore it.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 block/file-posix.c | 4 ++++
 1 file changed, 4 insertions(+)
diff mbox series

Patch

diff --git a/block/file-posix.c b/block/file-posix.c
index 53f475ed61..1dca220a81 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)) {