fs/xfs/xfs_mru_cache.c

12  * supplies an element lifetime in milliseconds and a group count, as well as a
23  * period in time.  When the first element is added, time zero for the data
28  * If an element is accessed at any point, it is removed from its list and
32  * have elapsed since the first element was added.  The reason for this is that
38  * (t + t/g) seconds, where t is the inactive element lifetime and g is the
50  * introduces a granularity to element lifetimes, so there's no point storing an
51  * individual timeout with each element that specifies a more precise reap time.
52  * The bonus is a saving of sizeof(long) bytes of memory per element stored.
57  * removing an element would involve walking large portions of the entire list,
61  * When an element is touched or deleted, it needs to be removed from its
99 	unsigned long		time_zero; /* Time first element was added. */
116  * has been advanced sufficiently to be within the immediate element lifetime.
184  * When inserting or doing a lookup, an element needs to be inserted into the
186  * up-to-date, otherwise the new element could be given a shorter lifetime in
214 	/* Insert the element at the tail of the corresponding list. */  in _xfs_mru_cache_list_insert()
220  * list need to be deleted.  For each element this involves removing it from the
222  * function and deleting the element from the element zone.
238 		/* Remove the element from the data store. */  in _xfs_mru_cache_clear_reap_list()
414  * To insert an element, call xfs_mru_cache_insert() with the data store, the
415  * element's key and the client data pointer.  This function returns 0 on
416  * success or ENOMEM if memory for the data element couldn't be allocated.
447  * To remove an element without calling the free function, call
448  * xfs_mru_cache_remove() with the data store and the element's key.  On success
449  * the client data pointer for the removed element is returned, otherwise this
473  * To remove and element and call the free function, call xfs_mru_cache_delete()
474  * with the data store and the element's key.
489  * To look up an element using its key, call xfs_mru_cache_lookup() with the
490  * data store and the element's key.  If found, the element will be moved to the
499  * of the returned data structure, the extra per-element memory isn't warranted.
501  * If the element isn't found, this function returns NULL and the spinlock is