UBI: simplify PEB protection code
UBI has 2 RB-trees to implement PEB protection, which is too
much for simply prevent PEB from being moved for some time.
This patch implements this using lists. The benefits:
1. No need to allocate protection entry on each PEB get.
2. No need to maintain balanced trees and walk them.
Signed-off-by: Xiaochuan-Xu <xiaochuan-xu@cqu.edu.cn>
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
diff --git a/drivers/mtd/ubi/ubi.h b/drivers/mtd/ubi/ubi.h
index 46a4763..4a8ec48 100644
--- a/drivers/mtd/ubi/ubi.h
+++ b/drivers/mtd/ubi/ubi.h
@@ -74,6 +74,13 @@
#define UBI_IO_RETRIES 3
/*
+ * Length of the protection queue. The length is effectively equivalent to the
+ * number of (global) erase cycles PEBs are protected from the wear-leveling
+ * worker.
+ */
+#define UBI_PROT_QUEUE_LEN 10
+
+/*
* Error codes returned by the I/O sub-system.
*
* UBI_IO_PEB_EMPTY: the physical eraseblock is empty, i.e. it contains only
@@ -96,6 +103,7 @@
/**
* struct ubi_wl_entry - wear-leveling entry.
* @u.rb: link in the corresponding (free/used) RB-tree
+ * @u.list: link in the protection queue
* @ec: erase counter
* @pnum: physical eraseblock number
*
@@ -106,6 +114,7 @@
struct ubi_wl_entry {
union {
struct rb_node rb;
+ struct list_head list;
} u;
int ec;
int pnum;
@@ -290,7 +299,7 @@
* @beb_rsvd_level: normal level of PEBs reserved for bad PEB handling
*
* @autoresize_vol_id: ID of the volume which has to be auto-resized at the end
- * of UBI ititializetion
+ * of UBI initialization
* @vtbl_slots: how many slots are available in the volume table
* @vtbl_size: size of the volume table in bytes
* @vtbl: in-RAM volume table copy
@@ -308,18 +317,17 @@
* @used: RB-tree of used physical eraseblocks
* @free: RB-tree of free physical eraseblocks
* @scrub: RB-tree of physical eraseblocks which need scrubbing
- * @prot: protection trees
- * @prot.pnum: protection tree indexed by physical eraseblock numbers
- * @prot.aec: protection tree indexed by absolute erase counter value
- * @wl_lock: protects the @used, @free, @prot, @lookuptbl, @abs_ec, @move_from,
- * @move_to, @move_to_put @erase_pending, @wl_scheduled, and @works
- * fields
+ * @pq: protection queue (contain physical eraseblocks which are temporarily
+ * protected from the wear-leveling worker)
+ * @pq_head: protection queue head
+ * @wl_lock: protects the @used, @free, @pq, @pq_head, @lookuptbl, @move_from,
+ * @move_to, @move_to_put @erase_pending, @wl_scheduled and @works
+ * fields
* @move_mutex: serializes eraseblock moves
- * @work_sem: sycnhronizes the WL worker with use tasks
+ * @work_sem: synchronizes the WL worker with use tasks
* @wl_scheduled: non-zero if the wear-leveling was scheduled
* @lookuptbl: a table to quickly find a &struct ubi_wl_entry object for any
* physical eraseblock
- * @abs_ec: absolute erase counter
* @move_from: physical eraseblock from where the data is being moved
* @move_to: physical eraseblock where the data is being moved to
* @move_to_put: if the "to" PEB was put
@@ -353,11 +361,11 @@
*
* @peb_buf1: a buffer of PEB size used for different purposes
* @peb_buf2: another buffer of PEB size used for different purposes
- * @buf_mutex: proptects @peb_buf1 and @peb_buf2
+ * @buf_mutex: protects @peb_buf1 and @peb_buf2
* @ckvol_mutex: serializes static volume checking when opening
- * @mult_mutex: serializes operations on multiple volumes, like re-nameing
+ * @mult_mutex: serializes operations on multiple volumes, like re-naming
* @dbg_peb_buf: buffer of PEB size used for debugging
- * @dbg_buf_mutex: proptects @dbg_peb_buf
+ * @dbg_buf_mutex: protects @dbg_peb_buf
*/
struct ubi_device {
struct cdev cdev;
@@ -394,16 +402,13 @@
struct rb_root used;
struct rb_root free;
struct rb_root scrub;
- struct {
- struct rb_root pnum;
- struct rb_root aec;
- } prot;
+ struct list_head pq[UBI_PROT_QUEUE_LEN];
+ int pq_head;
spinlock_t wl_lock;
struct mutex move_mutex;
struct rw_semaphore work_sem;
int wl_scheduled;
struct ubi_wl_entry **lookuptbl;
- unsigned long long abs_ec;
struct ubi_wl_entry *move_from;
struct ubi_wl_entry *move_to;
int move_to_put;