Re: [Qemu-devel] [RFC PATCH 17/41] block: Request real permissions in blk_new_open()

[Max Reitz]

On 13.02.2017 18:22, Kevin Wolf wrote:
> We can figure out the necessary permissions from the flags that the
> caller passed.
> 
> Signed-off-by: Kevin Wolf 
> ---
>  block/block-backend.c | 16 ++--
>  1 file changed, 14 insertions(+), 2 deletions(-)
> 
> diff --git a/block/block-backend.c b/block/block-backend.c
> index 1f80854..e10a278 100644
> --- a/block/block-backend.c
> +++ b/block/block-backend.c
> @@ -160,6 +160,7 @@ BlockBackend *blk_new_open(const char *filename, const 
> char *reference,
>  {
>  BlockBackend *blk;
>  BlockDriverState *bs;
> +uint64_t perm;
>  
>  blk = blk_new(0, BLK_PERM_ALL);

What about this?

Max

>  bs = bdrv_open(filename, reference, options, flags, errp);
> @@ -168,9 +169,20 @@ BlockBackend *blk_new_open(const char *filename, const 
> char *reference,
>  return NULL;
>  }
>  
> -/* FIXME Use real permissions */
> +/* blk_new_open() is mainly used in .bdrv_create implementations and the
> + * tools where sharing isn't a concern because the BDS stays private, so 
> we
> + * just request permission according to the flags.
> + *
> + * The exceptions are xen_disk and blockdev_init(); in these cases, the
> + * caller of blk_new_open() doesn't make use of the permissions, but they
> + * shouldn't hurt either. We can still share everything here because the
> + * guest devices will add their own blockers if they can't share. */
> +perm = BLK_PERM_CONSISTENT_READ;
> +if (flags & BDRV_O_RDWR) {
> +perm |= BLK_PERM_WRITE;
> +}
>  blk->root = bdrv_root_attach_child(bs, "root", _root,
> -   0, BLK_PERM_ALL, blk, _abort);
> +   perm, BLK_PERM_ALL, blk, 
> _abort);
>  
>  return blk;
>  }
> 




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[Qemu-devel] [RFC PATCH 17/41] block: Request real permissions in blk_new_open()

[Kevin Wolf]

We can figure out the necessary permissions from the flags that the
caller passed.

Signed-off-by: Kevin Wolf 
---
 block/block-backend.c | 16 ++--
 1 file changed, 14 insertions(+), 2 deletions(-)

diff --git a/block/block-backend.c b/block/block-backend.c
index 1f80854..e10a278 100644
--- a/block/block-backend.c
+++ b/block/block-backend.c
@@ -160,6 +160,7 @@ BlockBackend *blk_new_open(const char *filename, const char 
*reference,
 {
 BlockBackend *blk;
 BlockDriverState *bs;
+uint64_t perm;
 
 blk = blk_new(0, BLK_PERM_ALL);
 bs = bdrv_open(filename, reference, options, flags, errp);
@@ -168,9 +169,20 @@ BlockBackend *blk_new_open(const char *filename, const 
char *reference,
 return NULL;
 }
 
-/* FIXME Use real permissions */
+/* blk_new_open() is mainly used in .bdrv_create implementations and the
+ * tools where sharing isn't a concern because the BDS stays private, so we
+ * just request permission according to the flags.
+ *
+ * The exceptions are xen_disk and blockdev_init(); in these cases, the
+ * caller of blk_new_open() doesn't make use of the permissions, but they
+ * shouldn't hurt either. We can still share everything here because the
+ * guest devices will add their own blockers if they can't share. */
+perm = BLK_PERM_CONSISTENT_READ;
+if (flags & BDRV_O_RDWR) {
+perm |= BLK_PERM_WRITE;
+}
 blk->root = bdrv_root_attach_child(bs, "root", _root,
-   0, BLK_PERM_ALL, blk, _abort);
+   perm, BLK_PERM_ALL, blk, _abort);
 
 return blk;
 }
-- 
1.8.3.1