btrfs: LLVMLinux: Remove VLAIS

Replaced the use of a Variable Length Array In Struct (VLAIS) with a C99
compliant equivalent.  This patch instead allocates the appropriate amount of
memory using a char array using the SHASH_DESC_ON_STACK macro.

The new code can be compiled with both gcc and clang.

Signed-off-by: Vinícius Tinti <viniciustinti@gmail.com>
Reviewed-by: Jan-Simon Möller <dl9pf@gmx.de>
Reviewed-by: Mark Charlebois <charlebm@gmail.com>
Signed-off-by: Behan Webster <behanw@converseincode.com>
Acked-by: Chris Mason <clm@fb.com>
Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
Cc: "David S. Miller" <davem@davemloft.net>

1 files changed, 7 insertions, 9 deletions

diff --git a/fs/btrfs/hash.c b/fs/btrfs/hash.c
index 64f15bb30a81..aae520b2aee5 100644
--- a/fs/btrfs/hash.c
+++ b/fs/btrfs/hash.c
@@ -31,18 +31,16 @@ void btrfs_hash_exit(void)
 
 u32 btrfs_crc32c(u32 crc, const void *address, unsigned int length)
 {
-        struct {
-                struct shash_desc shash;
-                char ctx[crypto_shash_descsize(tfm)];
-        } desc;
+        SHASH_DESC_ON_STACK(shash, tfm);
+        u32 *ctx = (u32 *)shash_desc_ctx(shash);
         int err;
 
-        desc.shash.tfm = tfm;
-        desc.shash.flags = 0;
-        *(u32 *)desc.ctx = crc;
+        shash->tfm = tfm;
+        shash->flags = 0;
+        *ctx = crc;
 
-        err = crypto_shash_update(&desc.shash, address, length);
+        err = crypto_shash_update(shash, address, length);
         BUG_ON(err);
 
-        return *(u32 *)desc.ctx;
+        return *ctx;
 }