block: use bvec_kmap_local in t10_pi_type1_{prepare,complete}

Using local kmaps slightly reduces the chances to stray writes, and
the bvec interface cleans up the code a little bit.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Link: https://lore.kernel.org/r/20210727055646.118787-15-hch@lst.deSigned-off-by: Jens Axboe <axboe@kernel.dk>

block/t10-pi.c

@@ -147,11 +147,10 @@ static void t10_pi_type1_prepare(struct request *rq)
 			break;
 
 		bip_for_each_vec(iv, bip, iter) {
-			void *p, *pmap;
 			unsigned int j;
+			void *p;
 
-			pmap = kmap_atomic(iv.bv_page);
-			p = pmap + iv.bv_offset;
+			p = bvec_kmap_local(&iv);
 			for (j = 0; j < iv.bv_len; j += tuple_sz) {
 				struct t10_pi_tuple *pi = p;
 
@@ -161,8 +160,7 @@ static void t10_pi_type1_prepare(struct request *rq)
 				ref_tag++;
 				p += tuple_sz;
 			}
-
-			kunmap_atomic(pmap);
+			kunmap_local(p);
 		}
 
 		bip->bip_flags |= BIP_MAPPED_INTEGRITY;
@@ -195,11 +193,10 @@ static void t10_pi_type1_complete(struct request *rq, unsigned int nr_bytes)
 		struct bvec_iter iter;
 
 		bip_for_each_vec(iv, bip, iter) {
-			void *p, *pmap;
 			unsigned int j;
+			void *p;
 
-			pmap = kmap_atomic(iv.bv_page);
-			p = pmap + iv.bv_offset;
+			p = bvec_kmap_local(&iv);
 			for (j = 0; j < iv.bv_len && intervals; j += tuple_sz) {
 				struct t10_pi_tuple *pi = p;
 
@@ -210,8 +207,7 @@ static void t10_pi_type1_complete(struct request *rq, unsigned int nr_bytes)
 				intervals--;
 				p += tuple_sz;
 			}
-
-			kunmap_atomic(pmap);
+			kunmap_local(p);
 		}
 	}
 }