cifs: DIO to/from KVEC-type iterators should now work

DIO to/from KVEC-type iterators should now work as the iterator is passed
down to the socket in non-RDMA/non-crypto mode and in RDMA or crypto mode
care is taken to handle vmap/vmalloc correctly and not take page refs when
building a scatterlist.

Signed-off-by: David Howells <[email protected]>
cc: Steve French <[email protected]>
cc: Shyam Prasad N <[email protected]>
cc: Rohith Surabattula <[email protected]>
cc: Tom Talpey <[email protected]>
cc: Jeff Layton <[email protected]>
cc: [email protected]
Signed-off-by: Steve French <[email protected]>

Author: dhowells

fs/cifs/file.c

@@ -3549,16 +3549,6 @@ static ssize_t __cifs_writev(
 	struct cifs_aio_ctx *ctx;
 	int rc;
 
-	/*
-	 * iov_iter_get_pages_alloc doesn't work with ITER_KVEC.
-	 * In this case, fall back to non-direct write function.
-	 * this could be improved by getting pages directly in ITER_KVEC
-	 */
-	if (direct && iov_iter_is_kvec(from)) {
-		cifs_dbg(FYI, "use non-direct cifs_writev for kvec I/O\n");
-		direct = false;
-	}
-
 	rc = generic_write_checks(iocb, from);
 	if (rc <= 0)
 		return rc;
@@ -4092,16 +4082,6 @@ static ssize_t __cifs_readv(
 	loff_t offset = iocb->ki_pos;
 	struct cifs_aio_ctx *ctx;
 
-	/*
-	 * iov_iter_get_pages_alloc() doesn't work with ITER_KVEC,
-	 * fall back to data copy read path
-	 * this could be improved by getting pages directly in ITER_KVEC
-	 */
-	if (direct && iov_iter_is_kvec(to)) {
-		cifs_dbg(FYI, "use non-direct cifs_user_readv for kvec I/O\n");
-		direct = false;
-	}
-
 	len = iov_iter_count(to);
 	if (!len)
 		return 0;