UBIFS: improve find function interface

Make 'ubifs_find_free_space()' return offset where free space starts,
rather than the amount of free space. This is just more appropriat
for its caller.

Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
diff --git a/fs/ubifs/journal.c b/fs/ubifs/journal.c
index a11ca09..a2d334e 100644
--- a/fs/ubifs/journal.c
+++ b/fs/ubifs/journal.c
@@ -114,7 +114,7 @@
  */
 static int reserve_space(struct ubifs_info *c, int jhead, int len)
 {
-	int err = 0, err1, retries = 0, avail, lnum, offs, free, squeeze;
+	int err = 0, err1, retries = 0, avail, lnum, offs, squeeze;
 	struct ubifs_wbuf *wbuf = &c->jheads[jhead].wbuf;
 
 	/*
@@ -139,10 +139,9 @@
 	 * Write buffer wasn't seek'ed or there is no enough space - look for an
 	 * LEB with some empty space.
 	 */
-	lnum = ubifs_find_free_space(c, len, &free, squeeze);
+	lnum = ubifs_find_free_space(c, len, &offs, squeeze);
 	if (lnum >= 0) {
 		/* Found an LEB, add it to the journal head */
-		offs = c->leb_size - free;
 		err = ubifs_add_bud_to_log(c, jhead, lnum, offs);
 		if (err)
 			goto out_return;