swiotlb: remove unused fields in io_tlb_mem

Commit 20347fca ("swiotlb: split up the global swiotlb lock") splits
io_tlb_mem into multiple areas. Each area has its own lock and index. The
global ones are not used so remove them.
Signed-off-by: Chao Gao <chao.gao@intel.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>

include/linux/swiotlb.h

@@ -79,11 +79,8 @@ dma_addr_t swiotlb_map(struct device *dev, phys_addr_t phys,
  * @used:	The number of used IO TLB block.
  * @list:	The free list describing the number of free entries available
  *		from each index.
- * @index:	The index to start searching in the next round.
  * @orig_addr:	The original address corresponding to a mapped entry.
  * @alloc_size:	Size of the allocated buffer.
- * @lock:	The lock to protect the above data structures in the map and
- *		unmap calls.
  * @debugfs:	The dentry to debugfs.
  * @late_alloc:	%true if allocated using the page allocator
  * @force_bounce: %true if swiotlb bouncing is forced
@@ -97,8 +94,6 @@ struct io_tlb_mem {
 	void *vaddr;
 	unsigned long nslabs;
 	unsigned long used;
-	unsigned int index;
-	spinlock_t lock;
 	struct dentry *debugfs;
 	bool late_alloc;
 	bool force_bounce;

kernel/dma/swiotlb.c

@@ -253,14 +253,12 @@ static void swiotlb_init_io_tlb_mem(struct io_tlb_mem *mem, phys_addr_t start,
 	mem->nslabs = nslabs;
 	mem->start = start;
 	mem->end = mem->start + bytes;
-	mem->index = 0;
 	mem->late_alloc = late_alloc;
 	mem->nareas = nareas;
 	mem->area_nslabs = nslabs / mem->nareas;
 
 	mem->force_bounce = swiotlb_force_bounce || (flags & SWIOTLB_FORCE);
 
-	spin_lock_init(&mem->lock);
 	for (i = 0; i < mem->nareas; i++) {
 		spin_lock_init(&mem->areas[i].lock);
 		mem->areas[i].index = 0;