[v3,3/8] qcow2: Declare BDRV_REQ_NO_FALLBACK supported
diff mbox series

Message ID 20191122160511.8377-4-kwolf@redhat.com
State New
Headers show
Series
  • block: Fix resize (extending) of short overlays
Related show

Commit Message

Kevin Wolf Nov. 22, 2019, 4:05 p.m. UTC
In the common case, qcow2_co_pwrite_zeroes() already only modifies
metadata case, so we're fine with or without BDRV_REQ_NO_FALLBACK set.

The only exception is when using an external data file, where the
request is passed down to the block driver of the external data file. We
are forwarding the BDRV_REQ_NO_FALLBACK flag there, though, so this is
fine, too.

Declare the flag supported therefore.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 block/qcow2.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

Comments

Eric Blake Nov. 22, 2019, 6:03 p.m. UTC | #1
On 11/22/19 10:05 AM, Kevin Wolf wrote:
> In the common case, qcow2_co_pwrite_zeroes() already only modifies
> metadata case, so we're fine with or without BDRV_REQ_NO_FALLBACK set.
> 
> The only exception is when using an external data file, where the
> request is passed down to the block driver of the external data file. We
> are forwarding the BDRV_REQ_NO_FALLBACK flag there, though, so this is
> fine, too.
> 
> Declare the flag supported therefore.
> 
> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> ---
>   block/qcow2.c | 3 ++-
>   1 file changed, 2 insertions(+), 1 deletion(-)

Reviewed-by: Eric Blake <eblake@redhat.com>

> 
> diff --git a/block/qcow2.c b/block/qcow2.c
> index b201383c3d..3fa10bf807 100644
> --- a/block/qcow2.c
> +++ b/block/qcow2.c
> @@ -1722,7 +1722,8 @@ static int coroutine_fn qcow2_do_open(BlockDriverState *bs, QDict *options,
>           }
>       }
>   
> -    bs->supported_zero_flags = header.version >= 3 ? BDRV_REQ_MAY_UNMAP : 0;
> +    bs->supported_zero_flags = header.version >= 3 ?
> +                               BDRV_REQ_MAY_UNMAP | BDRV_REQ_NO_FALLBACK : 0;
>   
>       /* Repair image if dirty */
>       if (!(flags & (BDRV_O_CHECK | BDRV_O_INACTIVE)) && !bs->read_only &&
>
Max Reitz Nov. 25, 2019, 12:02 p.m. UTC | #2
On 22.11.19 17:05, Kevin Wolf wrote:
> In the common case, qcow2_co_pwrite_zeroes() already only modifies
> metadata case, so we're fine with or without BDRV_REQ_NO_FALLBACK set.
> 
> The only exception is when using an external data file, where the
> request is passed down to the block driver of the external data file. We
> are forwarding the BDRV_REQ_NO_FALLBACK flag there, though, so this is
> fine, too.
> 
> Declare the flag supported therefore.
> 
> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> ---
>  block/qcow2.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)

Reviewed-by: Max Reitz <mreitz@redhat.com>
Alberto Garcia Nov. 25, 2019, 2:53 p.m. UTC | #3
On Fri 22 Nov 2019 05:05:06 PM CET, Kevin Wolf wrote:
> In the common case, qcow2_co_pwrite_zeroes() already only modifies
> metadata case, so we're fine with or without BDRV_REQ_NO_FALLBACK set.
>
> The only exception is when using an external data file, where the
> request is passed down to the block driver of the external data file. We
> are forwarding the BDRV_REQ_NO_FALLBACK flag there, though, so this is
> fine, too.
>
> Declare the flag supported therefore.
>
> Signed-off-by: Kevin Wolf <kwolf@redhat.com>

Reviewed-by: Alberto Garcia <berto@igalia.com>

Berto

Patch
diff mbox series

diff --git a/block/qcow2.c b/block/qcow2.c
index b201383c3d..3fa10bf807 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -1722,7 +1722,8 @@  static int coroutine_fn qcow2_do_open(BlockDriverState *bs, QDict *options,
         }
     }
 
-    bs->supported_zero_flags = header.version >= 3 ? BDRV_REQ_MAY_UNMAP : 0;
+    bs->supported_zero_flags = header.version >= 3 ?
+                               BDRV_REQ_MAY_UNMAP | BDRV_REQ_NO_FALLBACK : 0;
 
     /* Repair image if dirty */
     if (!(flags & (BDRV_O_CHECK | BDRV_O_INACTIVE)) && !bs->read_only &&