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>

fs/ubifs/find.c

@@ -478,7 +478,7 @@ const struct ubifs_lprops *do_find_free_space(struct ubifs_info *c,
  * ubifs_find_free_space - find a data LEB with free space.
  * @c: the UBIFS file-system description object
  * @min_space: minimum amount of required free space
- * @free: contains amount of free space in the LEB on exit
+ * @offs: contains offset of where free space starts on exit
  * @squeeze: whether to try to find space in a non-empty LEB first
  *
  * This function looks for an LEB with at least @min_space bytes of free space.
@@ -490,7 +490,7 @@ const struct ubifs_lprops *do_find_free_space(struct ubifs_info *c,
  * failed to find a LEB with @min_space bytes of free space and other a negative
  * error codes in case of failure.
  */
-int ubifs_find_free_space(struct ubifs_info *c, int min_space, int *free,
+int ubifs_find_free_space(struct ubifs_info *c, int min_space, int *offs,
 			  int squeeze)
 {
 	const struct ubifs_lprops *lprops;
@@ -558,10 +558,10 @@ int ubifs_find_free_space(struct ubifs_info *c, int min_space, int *free,
 		spin_unlock(&c->space_lock);
 	}
 
-	*free = lprops->free;
+	*offs = c->leb_size - lprops->free;
 	ubifs_release_lprops(c);
 
-	if (*free == c->leb_size) {
+	if (*offs == 0) {
 		/*
 		 * Ensure that empty LEBs have been unmapped. They may not have
 		 * been, for example, because of an unclean unmount.  Also
@@ -573,8 +573,8 @@ int ubifs_find_free_space(struct ubifs_info *c, int min_space, int *free,
 			return err;
 	}
 
-	dbg_find("found LEB %d, free %d", lnum, *free);
-	ubifs_assert(*free >= min_space);
+	dbg_find("found LEB %d, free %d", lnum, c->leb_size - *offs);
+	ubifs_assert(*offs <= c->leb_size - min_space);
 	return lnum;
 
 out:

fs/ubifs/journal.c

@@ -114,7 +114,7 @@ static inline void zero_trun_node_unused(struct ubifs_trun_node *trun)
  */
 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 @@ again:
 	 * 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;

fs/ubifs/ubifs.h

@@ -1500,7 +1500,7 @@ long long ubifs_reported_space(const struct ubifs_info *c, long long free);
 long long ubifs_calc_available(const struct ubifs_info *c, int min_idx_lebs);
 
 /* find.c */
-int ubifs_find_free_space(struct ubifs_info *c, int min_space, int *free,
+int ubifs_find_free_space(struct ubifs_info *c, int min_space, int *offs,
 			  int squeeze);
 int ubifs_find_free_leb_for_idx(struct ubifs_info *c);
 int ubifs_find_dirty_leb(struct ubifs_info *c, struct ubifs_lprops *ret_lp,