btrfs: replace for_each_set_bit() with for_each_set_bitmap()

Inside extent_io.c, there are several simple call sites doing things
like:

	for_each_set_bit(bit, bitmap, bitmap_size) {
		/* handle one fs block */
	}

The workload includes:

- set_bit()
  Inside extent_writepage_io().

  This can be replaced with a bitmap_set().

- btrfs_folio_set_lock()
- btrfs_mark_ordered_io_finished()
  Inside writepage_delalloc().

  Instead of calling it multiple times, we can pass a range into the
  function with one call.

Reviewed-by: Boris Burkov <boris@bur.io>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

Author: adam900710

fs/btrfs/extent_io.c

@@ -1426,8 +1426,9 @@ static noinline_for_stack int writepage_delalloc(struct btrfs_inode *inode,
 	u64 delalloc_start = page_start;
 	u64 delalloc_end = page_end;
 	u64 delalloc_to_write = 0;
+	unsigned int start_bit;
+	unsigned int end_bit;
 	int ret = 0;
-	int bit;
 
 	/* Save the dirty bitmap as our submission bitmap will be a subset of it. */
 	if (btrfs_is_subpage(fs_info, folio)) {
@@ -1437,10 +1438,12 @@ static noinline_for_stack int writepage_delalloc(struct btrfs_inode *inode,
 		bio_ctrl->submit_bitmap = 1;
 	}
 
-	for_each_set_bit(bit, &bio_ctrl->submit_bitmap, blocks_per_folio) {
-		u64 start = page_start + (bit << fs_info->sectorsize_bits);
+	for_each_set_bitrange(start_bit, end_bit, &bio_ctrl->submit_bitmap,
+			      blocks_per_folio) {
+		u64 start = page_start + (start_bit << fs_info->sectorsize_bits);
+		u32 len = (end_bit - start_bit) << fs_info->sectorsize_bits;
 
-		btrfs_folio_set_lock(fs_info, folio, start, fs_info->sectorsize);
+		btrfs_folio_set_lock(fs_info, folio, start, len);
 	}
 
 	/* Lock all (subpage) delalloc ranges inside the folio first. */
@@ -1557,10 +1560,13 @@ static noinline_for_stack int writepage_delalloc(struct btrfs_inode *inode,
 				fs_info->sectorsize_bits,
 				blocks_per_folio);
 
-		for_each_set_bit(bit, &bio_ctrl->submit_bitmap, bitmap_size)
-			btrfs_mark_ordered_io_finished(inode, folio,
-				page_start + (bit << fs_info->sectorsize_bits),
-				fs_info->sectorsize, false);
+		for_each_set_bitrange(start_bit, end_bit, &bio_ctrl->submit_bitmap,
+				      bitmap_size) {
+			u64 start = page_start + (start_bit << fs_info->sectorsize_bits);
+			u32 len = (end_bit - start_bit) << fs_info->sectorsize_bits;
+
+			btrfs_mark_ordered_io_finished(inode, folio, start, len, false);
+		}
 		return ret;
 	}
 out:
@@ -1728,8 +1734,8 @@ static noinline_for_stack int extent_writepage_io(struct btrfs_inode *inode,
 		return ret;
 	}
 
-	for (cur = start; cur < end; cur += fs_info->sectorsize)
-		set_bit((cur - folio_start) >> fs_info->sectorsize_bits, &range_bitmap);
+	bitmap_set(&range_bitmap, (start - folio_pos(folio)) >> fs_info->sectorsize_bits,
+		   len >> fs_info->sectorsize_bits);
 	bitmap_and(&bio_ctrl->submit_bitmap, &bio_ctrl->submit_bitmap, &range_bitmap,
 		   blocks_per_folio);