ocfs2: remove custom swap functions in favor of built-in sort swap

The custom swap functions used in ocfs2 do not perform any special
operations and can be replaced with the built-in swap function of sort. 
This change not only reduces code size but also improves efficiency,
especially in scenarios where CONFIG_RETPOLINE is enabled, as it makes
indirect function calls more expensive.

By using the built-in swap, we avoid these costly indirect function calls,
leading to better performance.

Link: https://lkml.kernel.org/r/20240810195316.186504-1-visitorckw@gmail.comSigned-off-by: Kuan-Wei Chiu <visitorckw@gmail.com>
Reviewed-by: Joseph Qi <joseph.qi@linux.alibaba.com>
Reviewed-by: Heming Zhao <heming.zhao@suse.com>
Cc: Ching-Chun (Jim) Huang <jserv@ccns.ncku.edu.tw>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Mark Fasheh <mark@fasheh.com>
Cc: Changwei Ge <gechangwei@live.cn>
Cc: Gang He <ghe@suse.com>
Cc: Jun Piao <piaojun@huawei.com>
Cc: Junxiao Bi <junxiao.bi@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

fs/ocfs2/dir.c

@@ -3511,16 +3511,6 @@ static int dx_leaf_sort_cmp(const void *a, const void *b)
 	return 0;
 }
 
-static void dx_leaf_sort_swap(void *a, void *b, int size)
-{
-	struct ocfs2_dx_entry *entry1 = a;
-	struct ocfs2_dx_entry *entry2 = b;
-
-	BUG_ON(size != sizeof(*entry1));
-
-	swap(*entry1, *entry2);
-}
-
 static int ocfs2_dx_leaf_same_major(struct ocfs2_dx_leaf *dx_leaf)
 {
 	struct ocfs2_dx_entry_list *dl_list = &dx_leaf->dl_list;
@@ -3781,7 +3771,7 @@ static int ocfs2_dx_dir_rebalance(struct ocfs2_super *osb, struct inode *dir,
 	 */
 	sort(dx_leaf->dl_list.de_entries, num_used,
 	     sizeof(struct ocfs2_dx_entry), dx_leaf_sort_cmp,
-	     dx_leaf_sort_swap);
+	     NULL);
 
 	ocfs2_journal_dirty(handle, dx_leaf_bh);
 

fs/ocfs2/refcounttree.c

@@ -1392,13 +1392,6 @@ static int cmp_refcount_rec_by_cpos(const void *a, const void *b)
 	return 0;
 }
 
-static void swap_refcount_rec(void *a, void *b, int size)
-{
-	struct ocfs2_refcount_rec *l = a, *r = b;
-
-	swap(*l, *r);
-}
-
 /*
  * The refcount cpos are ordered by their 64bit cpos,
  * But we will use the low 32 bit to be the e_cpos in the b-tree.
@@ -1474,7 +1467,7 @@ static int ocfs2_divide_leaf_refcount_block(struct buffer_head *ref_leaf_bh,
 	 */
 	sort(&rl->rl_recs, le16_to_cpu(rl->rl_used),
 	     sizeof(struct ocfs2_refcount_rec),
-	     cmp_refcount_rec_by_low_cpos, swap_refcount_rec);
+	     cmp_refcount_rec_by_low_cpos, NULL);
 
 	ret = ocfs2_find_refcount_split_pos(rl, &cpos, &split_index);
 	if (ret) {
@@ -1499,11 +1492,11 @@ static int ocfs2_divide_leaf_refcount_block(struct buffer_head *ref_leaf_bh,
 
 	sort(&rl->rl_recs, le16_to_cpu(rl->rl_used),
 	     sizeof(struct ocfs2_refcount_rec),
-	     cmp_refcount_rec_by_cpos, swap_refcount_rec);
+	     cmp_refcount_rec_by_cpos, NULL);
 
 	sort(&new_rl->rl_recs, le16_to_cpu(new_rl->rl_used),
 	     sizeof(struct ocfs2_refcount_rec),
-	     cmp_refcount_rec_by_cpos, swap_refcount_rec);
+	     cmp_refcount_rec_by_cpos, NULL);
 
 	*split_cpos = cpos;
 	return 0;

fs/ocfs2/xattr.c

@@ -4167,15 +4167,6 @@ static int cmp_xe(const void *a, const void *b)
 	return 0;
 }
 
-static void swap_xe(void *a, void *b, int size)
-{
-	struct ocfs2_xattr_entry *l = a, *r = b, tmp;
-
-	tmp = *l;
-	memcpy(l, r, sizeof(struct ocfs2_xattr_entry));
-	memcpy(r, &tmp, sizeof(struct ocfs2_xattr_entry));
-}
-
 /*
  * When the ocfs2_xattr_block is filled up, new bucket will be created
  * and all the xattr entries will be moved to the new bucket.
@@ -4241,7 +4232,7 @@ static void ocfs2_cp_xattr_block_to_bucket(struct inode *inode,
 	trace_ocfs2_cp_xattr_block_to_bucket_end(offset, size, off_change);
 
 	sort(target + offset, count, sizeof(struct ocfs2_xattr_entry),
-	     cmp_xe, swap_xe);
+	     cmp_xe, NULL);
 }
 
 /*
@@ -4436,7 +4427,7 @@ static int ocfs2_defrag_xattr_bucket(struct inode *inode,
 	 */
 	sort(entries, le16_to_cpu(xh->xh_count),
 	     sizeof(struct ocfs2_xattr_entry),
-	     cmp_xe_offset, swap_xe);
+	     cmp_xe_offset, NULL);
 
 	/* Move all name/values to the end of the bucket. */
 	xe = xh->xh_entries;
@@ -4478,7 +4469,7 @@ static int ocfs2_defrag_xattr_bucket(struct inode *inode,
 	/* sort the entries by their name_hash. */
 	sort(entries, le16_to_cpu(xh->xh_count),
 	     sizeof(struct ocfs2_xattr_entry),
-	     cmp_xe, swap_xe);
+	     cmp_xe, NULL);
 
 	buf = bucket_buf;
 	for (i = 0; i < bucket->bu_blocks; i++, buf += blocksize)