[4.2.y-ckt stable] Patch "ubi: fastmap: Implement produce_free_peb()" has been added to staging queue

[Kamal Mostafa]

This is a note to let you know that I have just added a patch titled

    ubi: fastmap: Implement produce_free_peb()

to the linux-4.2.y-queue branch of the 4.2.y-ckt extended stable tree 
which can be found at:

    http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-4.2.y-queue

This patch is scheduled to be released in version 4.2.8-ckt1.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 4.2.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

------

>From 74dfbf49462d6dec4793277c4baccf74ccab8d9b Mon Sep 17 00:00:00 2001
From: Richard Weinberger <richard at nod.at>
Date: Tue, 11 Aug 2015 23:27:44 +0200
Subject: ubi: fastmap: Implement produce_free_peb()
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

commit 1cb8f9776c7dcadc57885c6653943511d282633b upstream.

If fastmap requests a free PEB for a pool and UBI is busy
with erasing PEBs we need to offer a function to wait for one.
We can reuse produce_free_peb() from the non-fastmap WL code
but with different locking semantics.

Reported-and-tested-by: Jörg Krause <joerg.krause at embedded.rocks>
Signed-off-by: Richard Weinberger <richard at nod.at>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 drivers/mtd/ubi/fastmap-wl.c | 29 +++++++++++++++++++++++++++++
 1 file changed, 29 insertions(+)

diff --git a/drivers/mtd/ubi/fastmap-wl.c b/drivers/mtd/ubi/fastmap-wl.c
index b2a6653..30d3999 100644
--- a/drivers/mtd/ubi/fastmap-wl.c
+++ b/drivers/mtd/ubi/fastmap-wl.c
@@ -172,6 +172,30 @@ void ubi_refill_pools(struct ubi_device *ubi)
 }

 /**
+ * produce_free_peb - produce a free physical eraseblock.
+ * @ubi: UBI device description object
+ *
+ * This function tries to make a free PEB by means of synchronous execution of
+ * pending works. This may be needed if, for example the background thread is
+ * disabled. Returns zero in case of success and a negative error code in case
+ * of failure.
+ */
+static int produce_free_peb(struct ubi_device *ubi)
+{
+	int err;
+
+	while (!ubi->free.rb_node && ubi->works_count) {
+		dbg_wl("do one work synchronously");
+		err = do_work(ubi);
+
+		if (err)
+			return err;
+	}
+
+	return 0;
+}
+
+/**
  * ubi_wl_get_peb - get a physical eraseblock.
  * @ubi: UBI device description object
  *
@@ -213,6 +237,11 @@ again:
 		}
 		retried = 1;
 		up_read(&ubi->fm_eba_sem);
+		ret = produce_free_peb(ubi);
+		if (ret < 0) {
+			down_read(&ubi->fm_eba_sem);
+			goto out;
+		}
 		goto again;
 	}

--
1.9.1