afs: convert pagevec to folio_batch in afs_extend_writeback()

Patch series "Remove pagevecs".

Removes a folio->page->folio conversion for each folio that's involved. 
More importantly, removes one of the last few uses of a pagevec.

Link: https://lkml.kernel.org/r/20230621164557.3510324-1-willy@infradead.org
Link: https://lkml.kernel.org/r/20230621164557.3510324-2-willy@infradead.orgSigned-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

fs/afs/write.c

@@ -465,7 +465,7 @@ static void afs_extend_writeback(struct address_space *mapping,
 				 bool caching,
 				 unsigned int *_len)
 {
-	struct pagevec pvec;
+	struct folio_batch fbatch;
 	struct folio *folio;
 	unsigned long priv;
 	unsigned int psize, filler = 0;
@@ -476,7 +476,7 @@ static void afs_extend_writeback(struct address_space *mapping,
 	unsigned int i;
 
 	XA_STATE(xas, &mapping->i_pages, index);
-	pagevec_init(&pvec);
+	folio_batch_init(&fbatch);
 
 	do {
 		/* Firstly, we gather up a batch of contiguous dirty pages
@@ -535,7 +535,7 @@ static void afs_extend_writeback(struct address_space *mapping,
 				stop = false;
 
 			index += folio_nr_pages(folio);
-			if (!pagevec_add(&pvec, &folio->page))
+			if (!folio_batch_add(&fbatch, folio))
 				break;
 			if (stop)
 				break;
@@ -545,14 +545,14 @@ static void afs_extend_writeback(struct address_space *mapping,
 			xas_pause(&xas);
 		rcu_read_unlock();
 
-		/* Now, if we obtained any pages, we can shift them to being
+		/* Now, if we obtained any folios, we can shift them to being
 		 * writable and mark them for caching.
 		 */
-		if (!pagevec_count(&pvec))
+		if (!folio_batch_count(&fbatch))
 			break;
 
-		for (i = 0; i < pagevec_count(&pvec); i++) {
-			folio = page_folio(pvec.pages[i]);
+		for (i = 0; i < folio_batch_count(&fbatch); i++) {
+			folio = fbatch.folios[i];
 			trace_afs_folio_dirty(vnode, tracepoint_string("store+"), folio);
 
 			if (!folio_clear_dirty_for_io(folio))
@@ -565,7 +565,7 @@ static void afs_extend_writeback(struct address_space *mapping,
 			folio_unlock(folio);
 		}
 
-		pagevec_release(&pvec);
+		folio_batch_release(&fbatch);
 		cond_resched();
 	} while (!stop);