ubi: Fix producing anchor PEBs
When a new fastmap is about to be written UBI must make sure it has a
free block for a fastmap anchor available. For this ubi_update_fastmap()
calls ubi_ensure_anchor_pebs(). This stopped working with 2e8f08deabbc
("ubi: Fix races around ubi_refill_pools()"), with this commit the wear
leveling code is blocked and can no longer produce free PEBs. UBI then
more often than not falls back to write the new fastmap anchor to the
same block it was already on which means the same erase block gets
erased during each fastmap write and wears out quite fast.
As the locking prevents us from producing the anchor PEB when we
actually need it, this patch changes the strategy for creating the
anchor PEB. We no longer create it on demand right before we want to
write a fastmap, but instead we create an anchor PEB right after we have
written a fastmap. This gives us enough time to produce a new anchor PEB
before it is needed. To make sure we have an anchor PEB for the very
first fastmap write we call ubi_ensure_anchor_pebs() during
initialisation as well.
Fixes: 2e8f08deabbc ("ubi: Fix races around ubi_refill_pools()")
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: Richard Weinberger <richard@nod.at>
diff --git a/drivers/mtd/ubi/fastmap-wl.c b/drivers/mtd/ubi/fastmap-wl.c
index c44c847..426820a 100644
--- a/drivers/mtd/ubi/fastmap-wl.c
+++ b/drivers/mtd/ubi/fastmap-wl.c
@@ -57,18 +57,6 @@
}
}
-static int anchor_pebs_available(struct rb_root *root)
-{
- struct rb_node *p;
- struct ubi_wl_entry *e;
-
- ubi_rb_for_each_entry(p, e, root, u.rb)
- if (e->pnum < UBI_FM_MAX_START)
- return 1;
-
- return 0;
-}
-
/**
* ubi_wl_get_fm_peb - find a physical erase block with a given maximal number.
* @ubi: UBI device description object
@@ -277,8 +265,26 @@
int ubi_ensure_anchor_pebs(struct ubi_device *ubi)
{
struct ubi_work *wrk;
+ struct ubi_wl_entry *anchor;
spin_lock(&ubi->wl_lock);
+
+ /* Do we already have an anchor? */
+ if (ubi->fm_anchor) {
+ spin_unlock(&ubi->wl_lock);
+ return 0;
+ }
+
+ /* See if we can find an anchor PEB on the list of free PEBs */
+ anchor = ubi_wl_get_fm_peb(ubi, 1);
+ if (anchor) {
+ ubi->fm_anchor = anchor;
+ spin_unlock(&ubi->wl_lock);
+ return 0;
+ }
+
+ /* No luck, trigger wear leveling to produce a new anchor PEB */
+ ubi->fm_do_produce_anchor = 1;
if (ubi->wl_scheduled) {
spin_unlock(&ubi->wl_lock);
return 0;
@@ -294,7 +300,6 @@
return -ENOMEM;
}
- wrk->anchor = 1;
wrk->func = &wear_leveling_worker;
__schedule_ubi_work(ubi, wrk);
return 0;
diff --git a/drivers/mtd/ubi/fastmap.c b/drivers/mtd/ubi/fastmap.c
index 30621c6..1c7be4e 100644
--- a/drivers/mtd/ubi/fastmap.c
+++ b/drivers/mtd/ubi/fastmap.c
@@ -1540,14 +1540,6 @@
return 0;
}
- ret = ubi_ensure_anchor_pebs(ubi);
- if (ret) {
- up_write(&ubi->fm_eba_sem);
- up_write(&ubi->work_sem);
- up_write(&ubi->fm_protect);
- return ret;
- }
-
new_fm = kzalloc(sizeof(*new_fm), GFP_KERNEL);
if (!new_fm) {
up_write(&ubi->fm_eba_sem);
@@ -1618,7 +1610,8 @@
}
spin_lock(&ubi->wl_lock);
- tmp_e = ubi_wl_get_fm_peb(ubi, 1);
+ tmp_e = ubi->fm_anchor;
+ ubi->fm_anchor = NULL;
spin_unlock(&ubi->wl_lock);
if (old_fm) {
@@ -1670,6 +1663,9 @@
up_write(&ubi->work_sem);
up_write(&ubi->fm_protect);
kfree(old_fm);
+
+ ubi_ensure_anchor_pebs(ubi);
+
return ret;
err:
diff --git a/drivers/mtd/ubi/ubi.h b/drivers/mtd/ubi/ubi.h
index 75e818ca..9688b41 100644
--- a/drivers/mtd/ubi/ubi.h
+++ b/drivers/mtd/ubi/ubi.h
@@ -491,6 +491,8 @@
* @fm_work: fastmap work queue
* @fm_work_scheduled: non-zero if fastmap work was scheduled
* @fast_attach: non-zero if UBI was attached by fastmap
+ * @fm_anchor: The next anchor PEB to use for fastmap
+ * @fm_do_produce_anchor: If true produce an anchor PEB in wl
*
* @used: RB-tree of used physical eraseblocks
* @erroneous: RB-tree of erroneous used physical eraseblocks
@@ -599,6 +601,8 @@
struct work_struct fm_work;
int fm_work_scheduled;
int fast_attach;
+ struct ubi_wl_entry *fm_anchor;
+ int fm_do_produce_anchor;
/* Wear-leveling sub-system's stuff */
struct rb_root used;
@@ -789,7 +793,6 @@
* @vol_id: the volume ID on which this erasure is being performed
* @lnum: the logical eraseblock number
* @torture: if the physical eraseblock has to be tortured
- * @anchor: produce a anchor PEB to by used by fastmap
*
* The @func pointer points to the worker function. If the @shutdown argument is
* not zero, the worker has to free the resources and exit immediately as the
@@ -805,7 +808,6 @@
int vol_id;
int lnum;
int torture;
- int anchor;
};
#include "debug.h"
diff --git a/drivers/mtd/ubi/wl.c b/drivers/mtd/ubi/wl.c
index 3fcdefe..5d77a38 100644
--- a/drivers/mtd/ubi/wl.c
+++ b/drivers/mtd/ubi/wl.c
@@ -339,13 +339,6 @@
}
}
- /* If no fastmap has been written and this WL entry can be used
- * as anchor PEB, hold it back and return the second best WL entry
- * such that fastmap can use the anchor PEB later. */
- if (prev_e && !ubi->fm_disabled &&
- !ubi->fm && e->pnum < UBI_FM_MAX_START)
- return prev_e;
-
return e;
}
@@ -656,9 +649,6 @@
{
int err, scrubbing = 0, torture = 0, protect = 0, erroneous = 0;
int erase = 0, keep = 0, vol_id = -1, lnum = -1;
-#ifdef CONFIG_MTD_UBI_FASTMAP
- int anchor = wrk->anchor;
-#endif
struct ubi_wl_entry *e1, *e2;
struct ubi_vid_io_buf *vidb;
struct ubi_vid_hdr *vid_hdr;
@@ -698,11 +688,7 @@
}
#ifdef CONFIG_MTD_UBI_FASTMAP
- /* Check whether we need to produce an anchor PEB */
- if (!anchor)
- anchor = !anchor_pebs_available(&ubi->free);
-
- if (anchor) {
+ if (ubi->fm_do_produce_anchor) {
e1 = find_anchor_wl_entry(&ubi->used);
if (!e1)
goto out_cancel;
@@ -719,6 +705,7 @@
self_check_in_wl_tree(ubi, e1, &ubi->used);
rb_erase(&e1->u.rb, &ubi->used);
dbg_wl("anchor-move PEB %d to PEB %d", e1->pnum, e2->pnum);
+ ubi->fm_do_produce_anchor = 0;
} else if (!ubi->scrub.rb_node) {
#else
if (!ubi->scrub.rb_node) {
@@ -1051,7 +1038,6 @@
goto out_cancel;
}
- wrk->anchor = 0;
wrk->func = &wear_leveling_worker;
if (nested)
__schedule_ubi_work(ubi, wrk);
@@ -1093,8 +1079,15 @@
err = sync_erase(ubi, e, wl_wrk->torture);
if (!err) {
spin_lock(&ubi->wl_lock);
- wl_tree_add(e, &ubi->free);
- ubi->free_count++;
+
+ if (!ubi->fm_anchor && e->pnum < UBI_FM_MAX_START) {
+ ubi->fm_anchor = e;
+ ubi->fm_do_produce_anchor = 0;
+ } else {
+ wl_tree_add(e, &ubi->free);
+ ubi->free_count++;
+ }
+
spin_unlock(&ubi->wl_lock);
/*
@@ -1882,6 +1875,9 @@
if (err)
goto out_free;
+#ifdef CONFIG_MTD_UBI_FASTMAP
+ ubi_ensure_anchor_pebs(ubi);
+#endif
return 0;
out_free:
diff --git a/drivers/mtd/ubi/wl.h b/drivers/mtd/ubi/wl.h
index a9e2d66..c93a532 100644
--- a/drivers/mtd/ubi/wl.h
+++ b/drivers/mtd/ubi/wl.h
@@ -2,7 +2,6 @@
#ifndef UBI_WL_H
#define UBI_WL_H
#ifdef CONFIG_MTD_UBI_FASTMAP
-static int anchor_pebs_available(struct rb_root *root);
static void update_fastmap_work_fn(struct work_struct *wrk);
static struct ubi_wl_entry *find_anchor_wl_entry(struct rb_root *root);
static struct ubi_wl_entry *get_peb_for_wl(struct ubi_device *ubi);
