f2fs: fix to cover __allocate_new_section() with curseg_lock

In order to avoid race with f2fs_do_replace_block().

Fixes: f5a53edc ("f2fs: support aligned pinned file")
Signed-off-by: NChao Yu <yuchao0@huawei.com>
Signed-off-by: NJaegeuk Kim <jaegeuk@kernel.org>

fs/f2fs/segment.c

@@ -2945,19 +2945,23 @@ static void __allocate_new_section(struct f2fs_sb_info *sbi, int type)
 
 void f2fs_allocate_new_section(struct f2fs_sb_info *sbi, int type)
 {
+	down_read(&SM_I(sbi)->curseg_lock);
 	down_write(&SIT_I(sbi)->sentry_lock);
 	__allocate_new_section(sbi, type);
 	up_write(&SIT_I(sbi)->sentry_lock);
+	up_read(&SM_I(sbi)->curseg_lock);
 }
 
 void f2fs_allocate_new_segments(struct f2fs_sb_info *sbi)
 {
 	int i;
 
+	down_read(&SM_I(sbi)->curseg_lock);
 	down_write(&SIT_I(sbi)->sentry_lock);
 	for (i = CURSEG_HOT_DATA; i <= CURSEG_COLD_DATA; i++)
 		__allocate_new_segment(sbi, i, false);
 	up_write(&SIT_I(sbi)->sentry_lock);
+	up_read(&SM_I(sbi)->curseg_lock);
 }
 
 static const struct segment_allocation default_salloc_ops = {