[Qemu-devel] [PATCH v2 1/5] block: Add zoned device model property

[Dmitry Fomichev <dmitry.fomichev@wdc.com>]

This commit adds Zoned Device Model (as defined in T10 ZBC and
T13 ZAC standards) as a block driver property, along with some
useful access functions.

A new backend driver permission, BLK_PERM_SUPPORT_ZONED, is also
introduced. Only the drivers having this permission will be allowed
to open zoned block devices.

No code is added yet to initialize or check the value of this new
property, therefore this commit doesn't change any functionality.

Signed-off-by: Dmitry Fomichev <dmitry.fomichev@wdc.com>
---
 block.c                   | 19 +++++++++++++++++++
 include/block/block.h     | 21 ++++++++++++++++++++-
 include/block/block_int.h |  4 ++++
 3 files changed, 43 insertions(+), 1 deletion(-)

diff --git a/block.c b/block.c
index 29e931e217..cbdf044d43 100644
--- a/block.c
+++ b/block.c
@@ -4671,6 +4671,25 @@ void bdrv_get_geometry(BlockDriverState *bs, uint64_t *nb_sectors_ptr)
     *nb_sectors_ptr = nb_sectors < 0 ? 0 : nb_sectors;
 }
 
+uint8_t bdrv_get_zoned_model(BlockDriverState *bs)
+{
+    if (bs->drv->bdrv_get_zoned_info) {
+        bs->drv->bdrv_get_zoned_info(bs);
+    }
+
+    return bs->bl.zoned_model;
+}
+
+uint8_t bdrv_is_zoned(BlockDriverState *bs)
+{
+    /*
+     * Host Aware zone devices are supposed to be able to work
+     * just like regular block devices. Thus, we only consider
+     * Host Managed devices to be zoned here.
+     */
+    return bdrv_get_zoned_model(bs) == BLK_ZONED_MODEL_HM;
+}
+
 bool bdrv_is_sg(BlockDriverState *bs)
 {
     return bs->sg;
diff --git a/include/block/block.h b/include/block/block.h
index 734c9d2f76..a465da31b8 100644
--- a/include/block/block.h
+++ b/include/block/block.h
@@ -266,18 +266,35 @@ enum {
      */
     BLK_PERM_GRAPH_MOD          = 0x10,
 
+    /** This permission is required to open zoned block devices. */
+    BLK_PERM_SUPPORT_ZONED      = 0x20,
+
     BLK_PERM_ALL                = 0x1f,
 
     DEFAULT_PERM_PASSTHROUGH    = BLK_PERM_CONSISTENT_READ
                                  | BLK_PERM_WRITE
                                  | BLK_PERM_WRITE_UNCHANGED
-                                 | BLK_PERM_RESIZE,
+                                 | BLK_PERM_RESIZE
+                                 | BLK_PERM_SUPPORT_ZONED,
 
     DEFAULT_PERM_UNCHANGED      = BLK_PERM_ALL & ~DEFAULT_PERM_PASSTHROUGH,
 };
 
 char *bdrv_perm_names(uint64_t perm);
 
+/*
+ * Known zoned device models.
+ *
+ * TODO For a Linux host, it could be preferrable to include
+ * /usr/include/linux/blkzoned.h instead of defining ZBD-specific
+ * values here.
+ */
+enum blk_zoned_model {
+    BLK_ZONED_MODEL_NONE, /* Regular block device */
+    BLK_ZONED_MODEL_HA,   /* Host-aware zoned block device */
+    BLK_ZONED_MODEL_HM,   /* Host-managed zoned block device */
+};
+
 /* disk I/O throttling */
 void bdrv_init(void);
 void bdrv_init_with_whitelist(void);
@@ -354,6 +371,8 @@ int64_t bdrv_get_allocated_file_size(BlockDriverState *bs);
 BlockMeasureInfo *bdrv_measure(BlockDriver *drv, QemuOpts *opts,
                                BlockDriverState *in_bs, Error **errp);
 void bdrv_get_geometry(BlockDriverState *bs, uint64_t *nb_sectors_ptr);
+uint8_t bdrv_get_zoned_model(BlockDriverState *bs);
+uint8_t bdrv_is_zoned(BlockDriverState *bs);
 void bdrv_refresh_limits(BlockDriverState *bs, Error **errp);
 int bdrv_commit(BlockDriverState *bs);
 int bdrv_change_backing_file(BlockDriverState *bs,
diff --git a/include/block/block_int.h b/include/block/block_int.h
index 50902531b7..73fbccbe8a 100644
--- a/include/block/block_int.h
+++ b/include/block/block_int.h
@@ -416,6 +416,7 @@ struct BlockDriver {
     bool (*bdrv_debug_is_suspended)(BlockDriverState *bs, const char *tag);
 
     void (*bdrv_refresh_limits)(BlockDriverState *bs, Error **errp);
+    void (*bdrv_get_zoned_info)(BlockDriverState *bs);
 
     /*
      * Returns 1 if newly created images are guaranteed to contain only
@@ -614,6 +615,9 @@ typedef struct BlockLimits {
 
     /* maximum number of iovec elements */
     int max_iov;
+
+    /* Zoned device model. Zero value indicates a regular block device */
+    uint8_t zoned_model;
 } BlockLimits;
 
 typedef struct BdrvOpBlocker BdrvOpBlocker;
-- 
2.21.0