From 7b1d9c4df0603fbc526226a9c5ef91118aa6c957 Mon Sep 17 00:00:00 2001 From: Max Reitz Date: Fri, 8 Nov 2019 13:34:51 +0100 Subject: [PATCH] block: Add bdrv_qapi_perm_to_blk_perm() MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit We need some way to correlate QAPI BlockPermission values with BLK_PERM_* flags. We could: (1) have the same order in the QAPI definition as the the BLK_PERM_* flags are in LSb-first order. However, then there is no guarantee that they actually match (e.g. when someone modifies the QAPI schema without thinking of the BLK_PERM_* definitions). We could add static assertions, but these would break what’s good about this solution, namely its simplicity. (2) define the BLK_PERM_* flags based on the BlockPermission values. But this way whenever someone were to modify the QAPI order (perfectly sensible in theory), the BLK_PERM_* values would change. Because these values are used for file locking, this might break file locking between different qemu versions. Therefore, go the slightly more cumbersome way: Add a function to translate from the QAPI constants to the BLK_PERM_* flags. Signed-off-by: Max Reitz Message-id: 20191108123455.39445-2-mreitz@redhat.com Reviewed-by: Vladimir Sementsov-Ogievskiy Signed-off-by: Max Reitz --- block.c | 18 ++++++++++++++++++ include/block/block.h | 1 + 2 files changed, 19 insertions(+) diff --git a/block.c b/block.c index 1b6f7c86e8..28eb5a774c 100644 --- a/block.c +++ b/block.c @@ -2227,6 +2227,24 @@ void bdrv_format_default_perms(BlockDriverState *bs, BdrvChild *c, *nshared = shared; } +uint64_t bdrv_qapi_perm_to_blk_perm(BlockPermission qapi_perm) +{ + static const uint64_t permissions[] = { + [BLOCK_PERMISSION_CONSISTENT_READ] = BLK_PERM_CONSISTENT_READ, + [BLOCK_PERMISSION_WRITE] = BLK_PERM_WRITE, + [BLOCK_PERMISSION_WRITE_UNCHANGED] = BLK_PERM_WRITE_UNCHANGED, + [BLOCK_PERMISSION_RESIZE] = BLK_PERM_RESIZE, + [BLOCK_PERMISSION_GRAPH_MOD] = BLK_PERM_GRAPH_MOD, + }; + + QEMU_BUILD_BUG_ON(ARRAY_SIZE(permissions) != BLOCK_PERMISSION__MAX); + QEMU_BUILD_BUG_ON(1UL << ARRAY_SIZE(permissions) != BLK_PERM_ALL + 1); + + assert(qapi_perm < BLOCK_PERMISSION__MAX); + + return permissions[qapi_perm]; +} + static void bdrv_replace_child_noperm(BdrvChild *child, BlockDriverState *new_bs) { diff --git a/include/block/block.h b/include/block/block.h index 1df9848e74..e9dcfef7fa 100644 --- a/include/block/block.h +++ b/include/block/block.h @@ -280,6 +280,7 @@ enum { }; char *bdrv_perm_names(uint64_t perm); +uint64_t bdrv_qapi_perm_to_blk_perm(BlockPermission qapi_perm); /* disk I/O throttling */ void bdrv_init(void);