Fix 3.18.8 breakage of UBI devices with EOF marker (e.g. WNDR4300)

This commit re-adds a patch from 3.14 that is required for UBI block
devices with an EOF marker to be successfully mounted.

Signed-off-by: Oliver Smith <oliver@8.c.9.b.0.7.4.0.1.0.0.2.ip6.arpa>
SVN-Revision: 44658

diff --git a/target/linux/generic/patches-3.18/490-mtd-ubi-add-EOF-marker-support.patch b/target/linux/generic/patches-3.18/490-mtd-ubi-add-EOF-marker-support.patch
new file mode 100644 (file)
index 0000000..cd02c13
--- /dev/null
+++ b/target/linux/generic/patches-3.18/490-mtd-ubi-add-EOF-marker-support.patch
@@ -0,0 +1,51 @@
+--- a/drivers/mtd/ubi/attach.c
++++ b/drivers/mtd/ubi/attach.c
+@@ -800,6 +800,13 @@ out_unlock:
+       return err;
+ }
+ 
++static bool ec_hdr_has_eof(struct ubi_ec_hdr *ech)
++{
++      return ech->padding1[0] == 'E' &&
++             ech->padding1[1] == 'O' &&
++             ech->padding1[2] == 'F';
++}
++
+ /**
+  * scan_peb - scan and process UBI headers of a PEB.
+  * @ubi: UBI device description object
+@@ -830,9 +837,21 @@ static int scan_peb(struct ubi_device *u
+               return 0;
+       }
+ 
+-      err = ubi_io_read_ec_hdr(ubi, pnum, ech, 0);
+-      if (err < 0)
+-              return err;
++      if (!ai->eof_found) {
++              err = ubi_io_read_ec_hdr(ubi, pnum, ech, 0);
++              if (err < 0)
++                      return err;
++
++              if (ec_hdr_has_eof(ech)) {
++                      ubi_msg("EOF marker found, PEBs from %d will be erased",
++                              pnum);
++                      ai->eof_found = true;
++              }
++      }
++
++      if (ai->eof_found)
++              err = UBI_IO_FF_BITFLIPS;
++
+       switch (err) {
+       case 0:
+               break;
+--- a/drivers/mtd/ubi/ubi.h
++++ b/drivers/mtd/ubi/ubi.h
+@@ -701,6 +701,7 @@ struct ubi_attach_info {
+       int mean_ec;
+       uint64_t ec_sum;
+       int ec_count;
++      bool eof_found;
+       struct kmem_cache *aeb_slab_cache;
+ };
+