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authorMax Reitz <mreitz@redhat.com>2019-05-22 19:03:46 +0200
committerKevin Wolf <kwolf@redhat.com>2019-06-18 16:41:10 +0200
commitc1087f12066a1ff34153dd10662c1a46a874087c (patch)
tree11bcae3d454cd19afb63da0c8047e9326e4456ff /include/block
parent094e36394481fd2c8493cec2a7c026f342232f15 (diff)
block: Add bdrv_child_refresh_perms()
If a block node uses bdrv_child_try_set_perm() to change the permission it takes on its child, the result may be very short-lived. If anything makes the block layer recalculate the permissions internally, it will invoke the node driver's .bdrv_child_perm() implementation. The permission/shared permissions masks that returns will then override the values previously passed to bdrv_child_try_set_perm(). If drivers want a child edge to have specific values for the permissions/shared permissions mask, it must return them in .bdrv_child_perm(). Consequentially, there is no need for them to pass the same values to bdrv_child_try_set_perm() then: It is better to have a function that invokes .bdrv_child_perm() and calls bdrv_child_try_set_perm() with the result. This patch adds such a function under the name of bdrv_child_refresh_perms(). Signed-off-by: Max Reitz <mreitz@redhat.com> Reviewed-by: Kevin Wolf <kwolf@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Diffstat (limited to 'include/block')
-rw-r--r--include/block/block_int.h15
1 files changed, 15 insertions, 0 deletions
diff --git a/include/block/block_int.h b/include/block/block_int.h
index a498c2670b..d6415b53c1 100644
--- a/include/block/block_int.h
+++ b/include/block/block_int.h
@@ -1165,9 +1165,24 @@ BdrvChild *bdrv_root_attach_child(BlockDriverState *child_bs,
void *opaque, Error **errp);
void bdrv_root_unref_child(BdrvChild *child);
+/**
+ * Sets a BdrvChild's permissions. Avoid if the parent is a BDS; use
+ * bdrv_child_refresh_perms() instead and make the parent's
+ * .bdrv_child_perm() implementation return the correct values.
+ */
int bdrv_child_try_set_perm(BdrvChild *c, uint64_t perm, uint64_t shared,
Error **errp);
+/**
+ * Calls bs->drv->bdrv_child_perm() and updates the child's permission
+ * masks with the result.
+ * Drivers should invoke this function whenever an event occurs that
+ * makes their .bdrv_child_perm() implementation return different
+ * values than before, but which will not result in the block layer
+ * automatically refreshing the permissions.
+ */
+int bdrv_child_refresh_perms(BlockDriverState *bs, BdrvChild *c, 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 */