Re: [PATCH v12 5/7] config: add check to block layer

[Dmitry Fomichev]

On Sun, 2022-10-16 at 22:51 +0800, Sam Li wrote:
> Putting zoned/non-zoned BlockDrivers on top of each other is not
> allowed.
> 
> Signed-off-by: Sam Li 
> Reviewed-by: Stefan Hajnoczi 
> Reviewed-by: Hannes Reinecke 

Reviewed-by: Dmitry Fomichev 

> ---
>  block.c  | 19 +++
>  block/file-posix.c   | 12 
>  block/raw-format.c   |  1 +
>  include/block/block_int-common.h |  5 +
>  4 files changed, 37 insertions(+)
> 
> diff --git a/block.c b/block.c
> index 1fbf6b9e69..5d6fa4a25a 100644
> --- a/block.c
> +++ b/block.c
> @@ -7951,6 +7951,25 @@ void bdrv_add_child(BlockDriverState *parent_bs,
> BlockDriverState *child_bs,
>  return;
>  }
>  
> +    /*
> + * Non-zoned block drivers do not follow zoned storage constraints
> + * (i.e. sequential writes to zones). Refuse mixing zoned and non-zoned
> + * drivers in a graph.
> + */
> +    if (!parent_bs->drv->supports_zoned_children &&
> +    child_bs->bl.zoned == BLK_Z_HM) {
> +    /*
> + * The host-aware model allows zoned storage constraints and random
> + * write. Allow mixing host-aware and non-zoned drivers. Using
> + * host-aware device as a regular device.
> + */
> +    error_setg(errp, "Cannot add a %s child to a %s parent",
> +   child_bs->bl.zoned == BLK_Z_HM ? "zoned" : "non-zoned",
> +   parent_bs->drv->supports_zoned_children ?
> +   "support zoned children" : "not support zoned children");
> +    return;
> +    }
> +
>  if (!QLIST_EMPTY(_bs->parents)) {
>  error_setg(errp, "The node %s already has a parent",
>     child_bs->node_name);
> diff --git a/block/file-posix.c b/block/file-posix.c
> index bd28e3eaea..7c5a330fc1 100644
> --- a/block/file-posix.c
> +++ b/block/file-posix.c
> @@ -776,6 +776,18 @@ static int raw_open_common(BlockDriverState *bs, QDict
> *options,
>  goto fail;
>  }
>  }
> +#ifdef CONFIG_BLKZONED
> +    /*
> + * The kernel page cache does not reliably work for writes to SWR zones
> + * of zoned block device because it can not guarantee the order of 
> writes.
> + */
> +    if ((strcmp(bs->drv->format_name, "zoned_host_device") == 0) &&
> +    (!(s->open_flags & O_DIRECT))) {
> +    error_setg(errp, "driver=zoned_host_device was specified, but it "
> +   "requires cache.direct=on, which was not specified.");
> +    return -EINVAL; /* No host kernel page cache */
> +    }
> +#endif
>  
>  if (S_ISBLK(st.st_mode)) {
>  #ifdef __linux__
> diff --git a/block/raw-format.c b/block/raw-format.c
> index bac43f1d25..18dc52a150 100644
> --- a/block/raw-format.c
> +++ b/block/raw-format.c
> @@ -615,6 +615,7 @@ static void raw_child_perm(BlockDriverState *bs, BdrvChild
> *c,
>  BlockDriver bdrv_raw = {
>  .format_name  = "raw",
>  .instance_size    = sizeof(BDRVRawState),
> +    .supports_zoned_children = true,
>  .bdrv_probe   = _probe,
>  .bdrv_reopen_prepare  = _reopen_prepare,
>  .bdrv_reopen_commit   = _reopen_commit,
> diff --git a/include/block/block_int-common.h b/include/block/block_int-
> common.h
> index cdc06e77a6..37dddc603c 100644
> --- a/include/block/block_int-common.h
> +++ b/include/block/block_int-common.h
> @@ -127,6 +127,11 @@ struct BlockDriver {
>   */
>  bool is_format;
>  
> +    /*
> + * Set to true if the BlockDriver supports zoned children.
> + */
> +    bool supports_zoned_children;
> +
>  /*
>   * Drivers not implementing bdrv_parse_filename nor bdrv_open should have
>   * this field set to true, except ones that are defined only by their

[PATCH v12 5/7] config: add check to block layer

[Sam Li]

Putting zoned/non-zoned BlockDrivers on top of each other is not
allowed.

Signed-off-by: Sam Li 
Reviewed-by: Stefan Hajnoczi 
Reviewed-by: Hannes Reinecke 
---
 block.c  | 19 +++
 block/file-posix.c   | 12 
 block/raw-format.c   |  1 +
 include/block/block_int-common.h |  5 +
 4 files changed, 37 insertions(+)

diff --git a/block.c b/block.c
index 1fbf6b9e69..5d6fa4a25a 100644
--- a/block.c
+++ b/block.c
@@ -7951,6 +7951,25 @@ void bdrv_add_child(BlockDriverState *parent_bs, 
BlockDriverState *child_bs,
 return;
 }
 
+/*
+ * Non-zoned block drivers do not follow zoned storage constraints
+ * (i.e. sequential writes to zones). Refuse mixing zoned and non-zoned
+ * drivers in a graph.
+ */
+if (!parent_bs->drv->supports_zoned_children &&
+child_bs->bl.zoned == BLK_Z_HM) {
+/*
+ * The host-aware model allows zoned storage constraints and random
+ * write. Allow mixing host-aware and non-zoned drivers. Using
+ * host-aware device as a regular device.
+ */
+error_setg(errp, "Cannot add a %s child to a %s parent",
+   child_bs->bl.zoned == BLK_Z_HM ? "zoned" : "non-zoned",
+   parent_bs->drv->supports_zoned_children ?
+   "support zoned children" : "not support zoned children");
+return;
+}
+
 if (!QLIST_EMPTY(_bs->parents)) {
 error_setg(errp, "The node %s already has a parent",
child_bs->node_name);
diff --git a/block/file-posix.c b/block/file-posix.c
index bd28e3eaea..7c5a330fc1 100644
--- a/block/file-posix.c
+++ b/block/file-posix.c
@@ -776,6 +776,18 @@ static int raw_open_common(BlockDriverState *bs, QDict 
*options,
 goto fail;
 }
 }
+#ifdef CONFIG_BLKZONED
+/*
+ * The kernel page cache does not reliably work for writes to SWR zones
+ * of zoned block device because it can not guarantee the order of writes.
+ */
+if ((strcmp(bs->drv->format_name, "zoned_host_device") == 0) &&
+(!(s->open_flags & O_DIRECT))) {
+error_setg(errp, "driver=zoned_host_device was specified, but it "
+   "requires cache.direct=on, which was not specified.");
+return -EINVAL; /* No host kernel page cache */
+}
+#endif
 
 if (S_ISBLK(st.st_mode)) {
 #ifdef __linux__
diff --git a/block/raw-format.c b/block/raw-format.c
index bac43f1d25..18dc52a150 100644
--- a/block/raw-format.c
+++ b/block/raw-format.c
@@ -615,6 +615,7 @@ static void raw_child_perm(BlockDriverState *bs, BdrvChild 
*c,
 BlockDriver bdrv_raw = {
 .format_name  = "raw",
 .instance_size= sizeof(BDRVRawState),
+.supports_zoned_children = true,
 .bdrv_probe   = _probe,
 .bdrv_reopen_prepare  = _reopen_prepare,
 .bdrv_reopen_commit   = _reopen_commit,
diff --git a/include/block/block_int-common.h b/include/block/block_int-common.h
index cdc06e77a6..37dddc603c 100644
--- a/include/block/block_int-common.h
+++ b/include/block/block_int-common.h
@@ -127,6 +127,11 @@ struct BlockDriver {
  */
 bool is_format;
 
+/*
+ * Set to true if the BlockDriver supports zoned children.
+ */
+bool supports_zoned_children;
+
 /*
  * Drivers not implementing bdrv_parse_filename nor bdrv_open should have
  * this field set to true, except ones that are defined only by their
-- 
2.37.3