UBI: fix eraseblock picking criteria

commit 7eb3aa65853e1b223bfc786b023b702018cb76c0 upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 4 insertions, 6 deletions

diff --git a/drivers/mtd/ubi/wl.c b/drivers/mtd/ubi/wl.c
index 12e44c90b32..25f18e9b643 100644
--- a/drivers/mtd/ubi/wl.c
+++ b/drivers/mtd/ubi/wl.c
@@ -386,7 +386,7 @@ static struct ubi_wl_entry *find_wl_entry(struct rb_root *root, int max)
  */
 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 ||
@@ -424,7 +424,7 @@ 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);
@@ -433,10 +433,8 @@ 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:
                 /*