ext4: move the calculation of wbc->nr_to_write to mpage_folio_done()

commit f922c8c upstream.

mpage_folio_done() should be a more appropriate place than
mpage_submit_folio() for updating the wbc->nr_to_write after we have
submitted a fully mapped folio. Preparing to make mpage_submit_folio()
allows to submit partially mapped folio that is still under processing.

Signed-off-by: Zhang Yi <[email protected]>
Reviewed-by: Jan Kara <[email protected]>
Reviewed-by: Baokun Li <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Theodore Ts'o <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>

Author: zhangyi089

fs/ext4/inode.c

@@ -2027,6 +2027,7 @@ int ext4_da_get_block_prep(struct inode *inode, sector_t iblock,
 static void mpage_folio_done(struct mpage_da_data *mpd, struct folio *folio)
 {
 	mpd->start_pos += folio_size(folio);
+	mpd->wbc->nr_to_write -= folio_nr_pages(folio);
 	folio_unlock(folio);
 }
 
@@ -2057,8 +2058,6 @@ static int mpage_submit_folio(struct mpage_da_data *mpd, struct folio *folio)
 	    !ext4_verity_in_progress(mpd->inode))
 		len = size & (len - 1);
 	err = ext4_bio_write_folio(&mpd->io_submit, folio, len);
-	if (!err)
-		mpd->wbc->nr_to_write -= folio_nr_pages(folio);
 
 	return err;
 }