mtd/ubi/wl.c

12  * physical eraseblocks and erase counters and knows nothing about logical
13  * eraseblocks, volumes, etc. From this sub-system's perspective all physical
14  * eraseblocks are of two types - used and free. Used physical eraseblocks are
15  * those that were "get" by the 'ubi_wl_get_peb()' function, and free physical
18  * Physical eraseblocks returned by 'ubi_wl_get_peb()' have only erase counter
19  * header. The rest of the physical eraseblock contains only %0xFF bytes.
21  * When physical eraseblocks are returned to the WL sub-system by means of the
27  * physical eraseblocks with low erase counter to free physical eraseblocks
30  * If the WL sub-system fails to erase a physical eraseblock, it marks it as
34  * in a physical eraseblock, it has to be moved. Technically this is the same
37  * As it was said, for the UBI sub-system all physical eraseblocks are either
42  * When the WL sub-system returns a physical eraseblock, the physical
44  * the physical eraseblock is not directly moved from the @wl->free tree to the
46  * physical eraseblock is temporarily stored (@wl->pq).
49  *  o we don't want to move physical eraseblocks just after we have given them
52  *  o there is a chance that the user will put the physical eraseblock very
55  * Physical eraseblocks stay protected only for limited time. But the "time" is
62  * To put it differently, each physical eraseblock has 2 main states: free and
71  * Depending on the sub-state, wear-leveling entries of the used physical
74  * Note, in this implementation, we keep a small in-RAM object for each physical
100 /* Number of physical eraseblocks reserved for wear-leveling purposes */
105  * exceeded, the WL sub-system starts moving data from used physical
106  * eraseblocks with low erase counter to free physical eraseblocks with high
112  * When a physical eraseblock is moved, the WL sub-system has to pick the target
113  * physical eraseblock to move to. The simplest way would be just to pick the
115  * to an unlimited wear of one or few physical eraseblock. Indeed, imagine a
116  * situation when the picked physical eraseblock is constantly erased after the
118  * counter of the free physical eraseblock to pick. Namely, the WL sub-system
141  * Note, we use (erase counter, physical eraseblock number) pairs as keys in
273  * prot_queue_add - add physical eraseblock to the protection queue.
275  * @e: the physical eraseblock to add
387 	 * Move the physical eraseblock to the protection queue where it will  in wl_get_wle()
398  * prot_queue_del - remove a physical eraseblock from the protection queue.
400  * @pnum: the physical eraseblock to remove
422  * sync_erase - synchronously erase a physical eraseblock.
424  * @e: the the physical eraseblock to erase
425  * @torture: if the physical eraseblock has to be tortured
496 	 * There may be several protected physical eraseblock to remove,  in serve_prot_queue()
595  * @e: the WL entry of the physical eraseblock to erase
598  * @torture: if the physical eraseblock has to be tortured
634  * @e: the WL entry of the physical eraseblock to erase
637  * @torture: if the physical eraseblock has to be tortured
666  * This function copies a more worn out physical eraseblock to a less worn out
697 		 * No free physical eraseblocks? Well, they must be waiting in
699 		 * triggered again when a free physical eraseblock appears.
701 		 * No used physical eraseblocks? They must be temporarily
732 		 * Now pick the least worn-out used physical eraseblock and a
733 		 * highly worn-out free physical eraseblock. If the erase
772 	 * Now we are going to copy physical eraseblock @e1->pnum to @e2->pnum.
773 	 * We so far do not know which logical eraseblock our physical
998 			/* No physical eraseblocks - no deal */
1003 		 * lowest erase counter of used physical eraseblocks and a high
1004 		 * erase counter of free physical eraseblocks is greater than
1049  * erase_worker - physical eraseblock erase worker function.
1055  * This function erases a physical eraseblock and perform torture testing if
1056  * needed. It also takes care about marking the physical eraseblock bad if
1091 		 * protected physical eraseblocks.
1120 		 * this physical eraseblock for erasure again would cause
1128 		ubi_err(ubi, "bad physical eraseblock %d detected", pnum);
1136 			ubi_err(ubi, "no reserved/available physical eraseblocks");
1190  * @pnum: physical eraseblock to return
1191  * @torture: if this physical eraseblock has to be tortured
1193  * This function is called to return physical eraseblock @pnum to the pool of
1194  * free physical eraseblocks. The @torture flag has to be set if an I/O error
1215 		 * User is putting the physical eraseblock which was selected to
1228 		 * User is putting the physical eraseblock which was selected
1281  * ubi_wl_scrub_peb - schedule a physical eraseblock for scrubbing.
1283  * @pnum: the physical eraseblock to schedule
1285  * If a bit-flip in a physical eraseblock is detected, this physical eraseblock
1286  * needs scrubbing. This function schedules a physical eraseblock for
1307 		 * This physical eraseblock was used to move data to. The data
1635 		ubi_err(ubi, "no enough physical eraseblocks (%d, need %d)",
1698  * @pnum: the physical eraseblock number to check
1701  * This function returns zero if the erase counter of physical eraseblock @pnum
1805  * produce_free_peb - produce a free physical eraseblock.
1832  * ubi_wl_get_peb - get a physical eraseblock.
1835  * This function returns a physical eraseblock in case of success and a