orangefs: adjust counting code to recover from 665575c

A late commit to 6.14-rc7! broke orangefs. 665575c seems like a
good change, but maybe should have been introduced during the merge
window. This patch adjusts the counting code associated with
writing out pages so that orangefs works in a 665575c world.

Signed-off-by: Mike Marshall <hubcap@omnibond.com>

Author: hubcapsc

fs/orangefs/inode.c

@@ -32,12 +32,13 @@ static int orangefs_writepage_locked(struct folio *folio,
 	len = i_size_read(inode);
 	if (folio->private) {
 		wr = folio->private;
-		WARN_ON(wr->pos >= len);
 		off = wr->pos;
-		if (off + wr->len > len)
+		if ((off + wr->len > len) && (off <= len))
 			wlen = len - off;
 		else
 			wlen = wr->len;
+		if (wlen == 0)
+			wlen = wr->len;
 	} else {
 		WARN_ON(1);
 		off = folio_pos(folio);
@@ -46,8 +47,6 @@ static int orangefs_writepage_locked(struct folio *folio,
 		if (wlen > len - off)
 			wlen = len - off;
 	}
-	/* Should've been handled in orangefs_invalidate_folio. */
-	WARN_ON(off == len || off + wlen > len);
 
 	WARN_ON(wlen == 0);
 	bvec_set_folio(&bv, folio, wlen, offset_in_folio(folio, off));
@@ -320,6 +319,8 @@ static int orangefs_write_begin(struct file *file,
 			wr->len += len;
 			goto okay;
 		} else {
+			wr->pos = pos;
+			wr->len = len;
 			ret = orangefs_launder_folio(folio);
 			if (ret)
 				return ret;