1 files changed, 47 insertions, 0 deletions

diff --git a/drivers/mtd/mtdconcat.c b/drivers/mtd/mtdconcat.c
index 3dbb1b38db66..792b547786b8 100644
--- a/drivers/mtd/mtdconcat.c
+++ b/drivers/mtd/mtdconcat.c
@@ -13,6 +13,7 @@
 #include <linux/slab.h>
 #include <linux/sched.h>
 #include <linux/types.h>
+#include <linux/backing-dev.h>
 
 #include <linux/mtd/mtd.h>
 #include <linux/mtd/concat.h>
@@ -684,6 +685,40 @@ static int concat_block_markbad(struct mtd_info *mtd, loff_t ofs)
 }
 
 /*
+ * try to support NOMMU mmaps on concatenated devices
+ * - we don't support subdev spanning as we can't guarantee it'll work
+ */
+static unsigned long concat_get_unmapped_area(struct mtd_info *mtd,
+                                              unsigned long len,
+                                              unsigned long offset,
+                                              unsigned long flags)
+{
+        struct mtd_concat *concat = CONCAT(mtd);
+        int i;
+
+        for (i = 0; i < concat->num_subdev; i++) {
+                struct mtd_info *subdev = concat->subdev[i];
+
+                if (offset >= subdev->size) {
+                        offset -= subdev->size;
+                        continue;
+                }
+
+                /* we've found the subdev over which the mapping will reside */
+                if (offset + len > subdev->size)
+                        return (unsigned long) -EINVAL;
+
+                if (subdev->get_unmapped_area)
+                        return subdev->get_unmapped_area(subdev, len, offset,
+                                                         flags);
+
+                break;
+        }
+
+        return (unsigned long) -ENOSYS;
+}
+
+/*
  * This function constructs a virtual MTD device by concatenating
  * num_devs MTD devices. A pointer to the new device object is
  * stored to *new_dev upon success. This function does _not_
@@ -740,6 +775,8 @@ struct mtd_info *mtd_concat_create(struct mtd_info *subdev[],	/* subdevices to c
 
         concat->mtd.ecc_stats.badblocks = subdev[0]->ecc_stats.badblocks;
 
+        concat->mtd.backing_dev_info = subdev[0]->backing_dev_info;
+
         concat->subdev[0] = subdev[0];
 
         for (i = 1; i < num_devs; i++) {
@@ -766,6 +803,15 @@ struct mtd_info *mtd_concat_create(struct mtd_info *subdev[],	/* subdevices to c
                                 concat->mtd.flags |=
                                     subdev[i]->flags & MTD_WRITEABLE;
                 }
+
+                /* only permit direct mapping if the BDIs are all the same
+                 * - copy-mapping is still permitted
+                 */
+                if (concat->mtd.backing_dev_info !=
+                    subdev[i]->backing_dev_info)
+                        concat->mtd.backing_dev_info =
+                                &default_backing_dev_info;
+
                 concat->mtd.size += subdev[i]->size;
                 concat->mtd.ecc_stats.badblocks +=
                         subdev[i]->ecc_stats.badblocks;
@@ -796,6 +842,7 @@ struct mtd_info *mtd_concat_create(struct mtd_info *subdev[],	/* subdevices to c
         concat->mtd.unlock = concat_unlock;
         concat->mtd.suspend = concat_suspend;
         concat->mtd.resume = concat_resume;
+        concat->mtd.get_unmapped_area = concat_get_unmapped_area;
 
         /*
          * Combine the erase block size info of the subdevices: