nilfs2: convert nilfs_find_uncommited_extent() to use filemap_get_folios_contig()

Convert function to use folios throughout.  This is in preparation for the
removal of find_get_pages_contig().  Now also supports large folios.

Also clean up an unnecessary if statement - pvec.pages[0]->index > index
will always evaluate to false, and filemap_get_folios_contig() returns 0
if there is no folio found at index.

Link: https://lkml.kernel.org/r/20220824004023.77310-6-vishal.moola@gmail.comSigned-off-by: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Acked-by: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Chris Mason <clm@fb.com>
Cc: David Sterba <dsterba@suse.com>
Cc: David Sterba <dsterb@suse.com>
Cc: Josef Bacik <josef@toxicpanda.com>
Cc: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

fs/nilfs2/page.c

@@ -480,41 +480,36 @@ unsigned long nilfs_find_uncommitted_extent(struct inode *inode,
 					    sector_t start_blk,
 					    sector_t *blkoff)
 {
-	unsigned int i;
+	unsigned int i, nr_folios;
 	pgoff_t index;
-	unsigned int nblocks_in_page;
 	unsigned long length = 0;
-	sector_t b;
-	struct pagevec pvec;
-	struct page *page;
+	struct folio_batch fbatch;
+	struct folio *folio;
 
 	if (inode->i_mapping->nrpages == 0)
 		return 0;
 
 	index = start_blk >> (PAGE_SHIFT - inode->i_blkbits);
-	nblocks_in_page = 1U << (PAGE_SHIFT - inode->i_blkbits);
 
-	pagevec_init(&pvec);
+	folio_batch_init(&fbatch);
 
 repeat:
-	pvec.nr = find_get_pages_contig(inode->i_mapping, index, PAGEVEC_SIZE,
-					pvec.pages);
-	if (pvec.nr == 0)
+	nr_folios = filemap_get_folios_contig(inode->i_mapping, &index, ULONG_MAX,
+			&fbatch);
+	if (nr_folios == 0)
 		return length;
 
-	if (length > 0 && pvec.pages[0]->index > index)
-		goto out;
-
-	b = pvec.pages[0]->index << (PAGE_SHIFT - inode->i_blkbits);
 	i = 0;
 	do {
-		page = pvec.pages[i];
+		folio = fbatch.folios[i];
 
-		lock_page(page);
-		if (page_has_buffers(page)) {
+		folio_lock(folio);
+		if (folio_buffers(folio)) {
 			struct buffer_head *bh, *head;
+			sector_t b;
 
-			bh = head = page_buffers(page);
+			b = folio->index << (PAGE_SHIFT - inode->i_blkbits);
+			bh = head = folio_buffers(folio);
 			do {
 				if (b < start_blk)
 					continue;
@@ -529,21 +524,17 @@ unsigned long nilfs_find_uncommitted_extent(struct inode *inode,
 		} else {
 			if (length > 0)
 				goto out_locked;
-
-			b += nblocks_in_page;
 		}
-		unlock_page(page);
+		folio_unlock(folio);
 
-	} while (++i < pagevec_count(&pvec));
+	} while (++i < nr_folios);
 
-	index = page->index + 1;
-	pagevec_release(&pvec);
+	folio_batch_release(&fbatch);
 	cond_resched();
 	goto repeat;
 
 out_locked:
-	unlock_page(page);
-out:
-	pagevec_release(&pvec);
+	folio_unlock(folio);
+	folio_batch_release(&fbatch);
 	return length;
 }