[PATCH 1/2] UBI: fix documentation and improve readability

[PATCH 1/2] UBI: fix documentation and improve readability

[Artem Bityutskiy]

From: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>

The "max" parameter of 'find_wl_entry()' was documented incorrectly and
it actually means the maximum possible difference from th smallest erase
counter. Rename it to "diff" instead, and amend the documentation.

Reported-by: Shmulik Ladkani <shmulik.ladkani@gmail.com>
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Reviewed-by: Shmulik Ladkani <shmulik.ladkani@gmail.com>
---
 drivers/mtd/ubi/wl.c |    9 +++++----
 1 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/drivers/mtd/ubi/wl.c b/drivers/mtd/ubi/wl.c
index 0696e36..8616f52 100644
--- a/drivers/mtd/ubi/wl.c
+++ b/drivers/mtd/ubi/wl.c
@@ -350,18 +350,19 @@ static void prot_queue_add(struct ubi_device *ubi, struct ubi_wl_entry *e)
 /**
  * find_wl_entry - find wear-leveling entry closest to certain erase counter.
  * @root: the RB-tree where to look for
- * @max: highest possible erase counter
+ * @diff: maximum possible difference from the smallest erase counter
  *
  * This function looks for a wear leveling entry with erase counter closest to
- * @max and less than @max.
+ * min + @diff, where min is the smallest erase counter.
  */
-static struct ubi_wl_entry *find_wl_entry(struct rb_root *root, int max)
+static struct ubi_wl_entry *find_wl_entry(struct rb_root *root, int diff)
 {
 	struct rb_node *p;
 	struct ubi_wl_entry *e;
+	int max;
 
 	e = rb_entry(rb_first(root), struct ubi_wl_entry, u.rb);
-	max += e->ec;
+	max = e->ec + diff;
 
 	p = root->rb_node;
 	while (p) {
-- 
1.7.9.1

[PATCH 2/2] UBI: fix eraseblock picking criteria

[Artem Bityutskiy]

From: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>

The 'find_wl_entry()' function expects the maximum difference as the second
argument, not the maximum absolute value. So the "unknown" eraseblock picking
was incorrect, as Shmulik Ladkani spotted. This patch fixes the issue.

Reported-by: Shmulik Ladkani <shmulik.ladkani@gmail.com>
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Reviewed-by: Shmulik Ladkani <shmulik.ladkani@gmail.com>
Cc: stable@kernel.org
---
 drivers/mtd/ubi/wl.c |   10 ++++------
 1 files changed, 4 insertions(+), 6 deletions(-)

diff --git a/drivers/mtd/ubi/wl.c b/drivers/mtd/ubi/wl.c
index 8616f52..512eab0 100644
--- a/drivers/mtd/ubi/wl.c
+++ b/drivers/mtd/ubi/wl.c
@@ -390,7 +390,7 @@ static struct ubi_wl_entry *find_wl_entry(struct rb_root *root, int diff)
  */
 int ubi_wl_get_peb(struct ubi_device *ubi, int dtype)
 {
-	int err, medium_ec;
+	int err;
 	struct ubi_wl_entry *e, *first, *last;
 
 	ubi_assert(dtype == UBI_LONGTERM || dtype == UBI_SHORTTERM ||
@@ -428,7 +428,7 @@ retry:
 		 * For unknown data we pick a physical eraseblock with medium
 		 * erase counter. But we by no means can pick a physical
 		 * eraseblock with erase counter greater or equivalent than the
-		 * lowest erase counter plus %WL_FREE_MAX_DIFF.
+		 * lowest erase counter plus %WL_FREE_MAX_DIFF/2.
 		 */
 		first = rb_entry(rb_first(&ubi->free), struct ubi_wl_entry,
 					u.rb);
@@ -437,10 +437,8 @@ retry:
 		if (last->ec - first->ec < WL_FREE_MAX_DIFF)
 			e = rb_entry(ubi->free.rb_node,
 					struct ubi_wl_entry, u.rb);
-		else {
-			medium_ec = (first->ec + WL_FREE_MAX_DIFF)/2;
-			e = find_wl_entry(&ubi->free, medium_ec);
-		}
+		else
+			e = find_wl_entry(&ubi->free, WL_FREE_MAX_DIFF/2);
 		break;
 	case UBI_SHORTTERM:
 		/*
-- 
1.7.9.1

Re: [PATCH 1/2] UBI: fix documentation and improve readability

[Shmulik Ladkani]

On Thu,  8 Mar 2012 16:21:30 +0200 Artem Bityutskiy <dedekind1@gmail.com> wrote:
> From: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
> 
> The "max" parameter of 'find_wl_entry()' was documented incorrectly and
> it actually means the maximum possible difference from th smallest erase

s/ th / the /

Regards,
Shmulik

Re: [PATCH 1/2] UBI: fix documentation and improve readability

[Artem Bityutskiy]

On Thu, 2012-03-08 at 17:57 +0200, Shmulik Ladkani wrote:
> On Thu,  8 Mar 2012 16:21:30 +0200 Artem Bityutskiy <dedekind1@gmail.com> wrote:
> > From: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
> > 
> > The "max" parameter of 'find_wl_entry()' was documented incorrectly and
> > it actually means the maximum possible difference from th smallest erase
> 
> s/ th / the /

Fixed, thanks!

-- 
Best Regards,
Artem Bityutskiy