crypto: acomp - define max size for destination

The acomp API allows to send requests with a NULL destination buffer. In
this case, the algorithm implementation needs to allocate the
destination scatter list, perform the operation and return the buffer to
the user. For decompression, data is likely to expand and be bigger
than the allocated buffer.

Define the maximum size (128KB) that acomp implementations will allocate
for decompression operations as destination buffer when they receive a
request with a NULL destination buffer.

Suggested-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Giovanni Cabiddu <giovanni.cabiddu@intel.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

include/crypto/acompress.h

@@ -11,6 +11,7 @@
 #include <linux/crypto.h>
 
 #define CRYPTO_ACOMP_ALLOC_OUTPUT	0x00000001
+#define CRYPTO_ACOMP_DST_MAX		131072
 
 /**
  * struct acomp_req - asynchronous (de)compression request