[v5] block: Fix resize (extending) of short overlays

[PATCH v5 6/9] file-posix: Support BDRV_REQ_ZERO_WRITE for truncate

Kevin Wolf posted 9 patches 5 years, 9 months ago

Diff against v1 v2 v3 v4 v6 v7
Download mbox

Maintainers: Stefan Weil <sw@weilnetz.de>, John Snow <jsnow@redhat.com>, Max Reitz <mreitz@redhat.com>, Paolo Bonzini <pbonzini@redhat.com>, Liu Yuan <namei.unix@gmail.com>, "Denis V. Lunev" <den@openvz.org>, Jeff Cody <codyprime@gmail.com>, Fam Zheng <fam@euphon.net>, Stefan Hajnoczi <stefanha@redhat.com>, "Richard W.M. Jones" <rjones@redhat.com>, Markus Armbruster <armbru@redhat.com>, Kevin Wolf <kwolf@redhat.com>, Jason Dillaman <dillaman@redhat.com>, Peter Lieven <pl@kamp.de>, Ronnie Sahlberg <ronniesahlberg@gmail.com>

There is a newer version of this series

Expand all Fold all

[PATCH v5 6/9] file-posix: Support BDRV_REQ_ZERO_WRITE for truncate

Posted by Kevin Wolf 5 years, 9 months ago

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>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Alberto Garcia <berto@igalia.com>
---
 block/file-posix.c | 4 ++++
 1 file changed, 4 insertions(+)

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)) {
-- 
2.25.3

Re: [PATCH v5 6/9] file-posix: Support BDRV_REQ_ZERO_WRITE for truncate

Posted by Max Reitz 5 years, 9 months ago

On 22.04.20 17:21, Kevin Wolf wrote:
> 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>
> Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
> Reviewed-by: Alberto Garcia <berto@igalia.com>
> ---
>  block/file-posix.c | 4 ++++
>  1 file changed, 4 insertions(+)

Reviewed-by: Max Reitz <mreitz@redhat.com>