mtd/ubi/wl.c

12  * physical eraseblocks and erase counters and knows nothing about logical
18  * Physical eraseblocks returned by 'ubi_wl_get_peb()' have only erase counter
27  * physical eraseblocks with low erase counter to free physical eraseblocks
28  * with high erase counter.
30  * If the WL sub-system fails to erase a physical eraseblock, it marks it as
56  * measured in erase cycles in this case. This is implemented with help of the
59  * head of the queue on each erase operation (for any eraseblock). So the
60  * length of the queue defines how may (global) erase cycles PEBs are protected.
82  * example, when we move a PEB with low erase counter, and we need to pick the
99  * Maximum difference between two erase counters. If this threshold is
101  * eraseblocks with low erase counter to free physical eraseblocks with high
102  * erase counter.
109  * one with the highest erase counter. But in certain workloads this could lead
112  * data is written to it. So, we have a constant which limits the highest erase
114  * does not pick eraseblocks with erase counter greater than the lowest erase
136  * Note, we use (erase counter, physical eraseblock number) pairs as keys in
300  * @e will stay for %UBI_PROT_QUEUE_LEN erase operations and will be
316  * find_wl_entry - find wear-leveling entry closest to certain erase counter.
319  * @diff: maximum possible difference from the smallest erase counter
320  * @pick_max: pick PEB even its erase counter beyonds 'min_ec + @diff'
322  * This function looks for a wear leveling entry with erase counter closest to
323  * min + @diff, where min is the smallest erase counter.
355  * find_mean_wl_entry - find wear-leveling entry with medium erase counter.
359  * This function looks for a wear leveling entry with medium erase counter,
360  * but not greater or equivalent than the lowest erase counter plus
443  * ubi_sync_erase - synchronously erase a physical eraseblock.
445  * @e: the physical eraseblock to erase
457 	dbg_wl("erase PEB %d, old EC %llu", e->pnum, ec);
475 		 * erase counters internally.
477 		ubi_err(ubi, "erase counter overflow at PEB %d, EC %llu",
506  * This function is called after each erase operation and removes PEBs from the
584  * schedule_erase - schedule an erase work.
586  * @e: the WL entry of the physical eraseblock to erase
624  * do_sync_erase - run the erase worker synchronously.
626  * @e: the WL entry of the physical eraseblock to erase
637 	dbg_wl("sync erase of PEB %i", e->pnum);
663 	int erase = 0, keep = 0, vol_id = -1, lnum = -1;
738 		 * highly worn-out free physical eraseblock. If the erase
822 			erase = 1;
918 		dbg_wl("PEB %d (LEB %d:%d) was put meanwhile, erase",
971 	if (erase) {
1050 		 * lowest erase counter of used physical eraseblocks and a high
1051 		 * erase counter of free physical eraseblocks is greater than
1089  * __erase_worker - physical eraseblock erase worker function.
1106 	dbg_wl("erase PEB %d EC %d LEB %d:%d",
1129 		 * One more erase operation has happened, take care about
1139 	ubi_err(ubi, "failed to erase PEB %d, error %d", pnum, err);
1525 	 * erase worker frees a wl entry under us.
1745  * erase_aeb - erase a PEB given in UBI attach info PEB
1748  * @sync: If true, erase synchronously. Otherwise schedule for erasure
1819 	list_for_each_entry_safe(aeb, tmp, &ai->erase, u.list) {
1904 			 * find any outdated fastmap anchors, hence we erase the
1992  * self_check_ec - make sure that the erase counter of a PEB is correct.
1995  * @ec: the erase counter to check
1997  * This function returns zero if the erase counter of physical eraseblock @pnum