> +/* > + * At most times, fine grained cluster lock is sufficient to protect
Can we call out those times, please? > + * the operations on sis->swap_map. Please be careful with the naming. You can call it 'si' because that's what the function argument is named. Or, swap_info_struct because that's the struct name. Calling it 'sis' is a bit sloppy, no? > No need to acquire gross grained "coarse" is a conventional antonym for "fine". > + * sis->lock. But cluster and cluster lock isn't available for HDD, > + * so sis->lock will be instead for them. > + */ > static inline struct swap_cluster_info *lock_cluster_or_swap_info( > struct swap_info_struct *si, > unsigned long offset) What I already knew was: there are two locks. We use one sometimes and the other at other times. What I don't know is why there are two locks, and the heuristics why we choose between them. This comment doesn't help explain the things I don't know.
