From: Anton Nefedov <anton.nefedov@virtuozzo.com>
To: qemu-devel@nongnu.org
Cc: qemu-block@nongnu.org, kwolf@redhat.com, mreitz@redhat.com,
stefanha@redhat.com, famz@redhat.com, eblake@redhat.com,
berto@igalia.com, Anton Nefedov <anton.nefedov@virtuozzo.com>
Subject: [Qemu-devel] [PATCH v3 2/2] block: fix write with zero flag set and iovector provided
Date: Wed, 14 Feb 2018 19:09:20 +0300 [thread overview]
Message-ID: <1518624560-38060-3-git-send-email-anton.nefedov@virtuozzo.com> (raw)
In-Reply-To: <1518624560-38060-1-git-send-email-anton.nefedov@virtuozzo.com>
The normal bdrv_co_pwritev() use is either
- BDRV_REQ_ZERO_WRITE clear and iovector provided
- BDRV_REQ_ZERO_WRITE set and iovector == NULL
while
- the flag clear and iovector == NULL is an assertion failure
in bdrv_co_do_zero_pwritev()
- the flag set and iovector provided is in fact allowed
(the flag prevails and zeroes are written)
However the alignment logic does not support the latter case so the padding
areas get overwritten with zeroes.
Currently, general functions like bdrv_rw_co() do provide iovector
regardless of flags. So, keep it supported and use bdrv_co_do_zero_pwritev()
alignment for it which also makes the code a bit more obvious anyway.
Signed-off-by: Anton Nefedov <anton.nefedov@virtuozzo.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Alberto Garcia <berto@igalia.com>
---
block/io.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/block/io.c b/block/io.c
index 89d0745..40df3be 100644
--- a/block/io.c
+++ b/block/io.c
@@ -1701,7 +1701,7 @@ int coroutine_fn bdrv_co_pwritev(BdrvChild *child,
*/
tracked_request_begin(&req, bs, offset, bytes, BDRV_TRACKED_WRITE);
- if (!qiov) {
+ if (flags & BDRV_REQ_ZERO_WRITE) {
ret = bdrv_co_do_zero_pwritev(child, offset, bytes, flags, &req);
goto out;
}
--
2.7.4
next prev parent reply other threads:[~2018-02-14 16:09 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-02-14 16:09 [Qemu-devel] [PATCH v3 0/2] block: fix write with zero flag set and iovector provided Anton Nefedov
2018-02-14 16:09 ` [Qemu-devel] [PATCH v3 1/2] iotest 033: add misaligned write-zeroes test via truncate Anton Nefedov
2018-02-14 18:31 ` Eric Blake
2018-02-14 16:09 ` Anton Nefedov [this message]
2018-02-14 17:28 ` [Qemu-devel] [PATCH v3 0/2] block: fix write with zero flag set and iovector provided Kevin Wolf
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