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[Qemu-devel] [PATCH v2 05/43] block: Default .bdrv_child_perm() for filt


From: Kevin Wolf
Subject: [Qemu-devel] [PATCH v2 05/43] block: Default .bdrv_child_perm() for filter drivers
Date: Mon, 27 Feb 2017 21:09:06 +0100

Most filters need permissions related to read and write for their
children, but only if the node has a parent that wants to use the same
operation on the filter. The same is true for resize.

This adds a default implementation that simply forwards all necessary
permissions to all children of the node and leaves the other permissions
unchanged.

Signed-off-by: Kevin Wolf <address@hidden>
---
 block.c                   | 24 ++++++++++++++++++++++++
 include/block/block_int.h |  8 ++++++++
 2 files changed, 32 insertions(+)

diff --git a/block.c b/block.c
index 803a688..597da9a 100644
--- a/block.c
+++ b/block.c
@@ -1531,6 +1531,30 @@ int bdrv_child_try_set_perm(BdrvChild *c, uint64_t perm, 
uint64_t shared,
     return 0;
 }
 
+#define DEFAULT_PERM_PASSTHROUGH (BLK_PERM_CONSISTENT_READ \
+                                 | BLK_PERM_WRITE \
+                                 | BLK_PERM_WRITE_UNCHANGED \
+                                 | BLK_PERM_RESIZE)
+#define DEFAULT_PERM_UNCHANGED (BLK_PERM_ALL & ~DEFAULT_PERM_PASSTHROUGH)
+
+void bdrv_filter_default_perms(BlockDriverState *bs, BdrvChild *c,
+                               const BdrvChildRole *role,
+                               uint64_t perm, uint64_t shared,
+                               uint64_t *nperm, uint64_t *nshared)
+{
+    if (c == NULL) {
+        *nperm = perm & DEFAULT_PERM_PASSTHROUGH;
+        *nshared = (shared & DEFAULT_PERM_PASSTHROUGH) | 
DEFAULT_PERM_UNCHANGED;
+        return;
+    }
+
+    *nperm = (perm & DEFAULT_PERM_PASSTHROUGH) |
+             (c->perm & DEFAULT_PERM_UNCHANGED);
+    *nshared = (shared & DEFAULT_PERM_PASSTHROUGH) |
+               (c->shared_perm & DEFAULT_PERM_UNCHANGED);
+}
+
+
 static void bdrv_replace_child(BdrvChild *child, BlockDriverState *new_bs)
 {
     BlockDriverState *old_bs = child->bs;
diff --git a/include/block/block_int.h b/include/block/block_int.h
index cef2b6e..17f4c2d 100644
--- a/include/block/block_int.h
+++ b/include/block/block_int.h
@@ -872,6 +872,14 @@ void bdrv_child_abort_perm_update(BdrvChild *c);
 int bdrv_child_try_set_perm(BdrvChild *c, uint64_t perm, uint64_t shared,
                             Error **errp);
 
+/* Default implementation for BlockDriver.bdrv_child_perm() that can be used by
+ * block filters: Forward CONSISTENT_READ, WRITE, WRITE_UNCHANGED and RESIZE to
+ * all children */
+void bdrv_filter_default_perms(BlockDriverState *bs, BdrvChild *c,
+                               const BdrvChildRole *role,
+                               uint64_t perm, uint64_t shared,
+                               uint64_t *nperm, uint64_t *nshared);
+
 
 const char *bdrv_get_parent_name(const BlockDriverState *bs);
 void blk_dev_change_media_cb(BlockBackend *blk, bool load);
-- 
1.8.3.1




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