io_uring/rsrc: get rid of io_mapped_ubuf->folio_mask

We don't really need to cache this, let's reclaim 8 bytes from struct
io_mapped_ubuf and just calculate it when we need it. The only hot path
here is io_import_fixed().
Signed-off-by: Jens Axboe <axboe@kernel.dk>

io_uring/rsrc.c

@@ -988,13 +988,10 @@ static int io_sqe_buffer_register(struct io_ring_ctx *ctx, struct iovec *iov,
 	imu->ubuf_end = imu->ubuf + iov->iov_len;
 	imu->nr_bvecs = nr_pages;
 	imu->folio_shift = PAGE_SHIFT;
-	imu->folio_mask = PAGE_MASK;
-	if (coalesced) {
+	if (coalesced)
 		imu->folio_shift = data.folio_shift;
-		imu->folio_mask = ~((1UL << data.folio_shift) - 1);
-	}
 	refcount_set(&imu->refs, 1);
-	off = (unsigned long) iov->iov_base & ~imu->folio_mask;
+	off = (unsigned long) iov->iov_base & ((1UL << imu->folio_shift) - 1);
 	*pimu = imu;
 	ret = 0;
 
@@ -1132,7 +1129,7 @@ int io_import_fixed(int ddir, struct iov_iter *iter,
 			iter->bvec = bvec + seg_skip;
 			iter->nr_segs -= seg_skip;
 			iter->count -= bvec->bv_len + offset;
-			iter->iov_offset = offset & ~imu->folio_mask;
+			iter->iov_offset = offset & ((1UL << imu->folio_shift) - 1);
 		}
 	}
 

io_uring/rsrc.h

@@ -46,7 +46,6 @@ struct io_mapped_ubuf {
 	unsigned int	nr_bvecs;
 	unsigned int    folio_shift;
 	unsigned long	acct_pages;
-	unsigned long   folio_mask;
 	refcount_t	refs;
 	struct bio_vec	bvec[] __counted_by(nr_bvecs);
 };