f2fs: return correct errno in f2fs_gc

BugLink: https://bugs.launchpad.net/bugs/1853881

[ Upstream commit 61f7725a ]

This fixes overriding error number in f2fs_gc.
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Connor Kuehl <connor.kuehl@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>

fs/f2fs/gc.c

@@ -880,7 +880,7 @@ int f2fs_gc(struct f2fs_sb_info *sbi, bool sync)
 
 	put_gc_inode(&gc_list);
 
-	if (sync)
+	if (sync && !ret)
 		ret = sec_freed ? 0 : -EAGAIN;
 	return ret;
 }