6 files changed, 67 insertions, 7 deletions

diff --git a/drivers/mtd/mtdchar.c b/drivers/mtd/mtdchar.c
index a825002123c..24d35ba62b8 100644
--- a/drivers/mtd/mtdchar.c
+++ b/drivers/mtd/mtdchar.c
@@ -477,6 +477,39 @@ static int mtd_do_readoob(struct mtd_info *mtd, uint64_t start,
         return ret;
 }
 
+/*
+ * Copies (and truncates, if necessary) data from the larger struct,
+ * nand_ecclayout, to the smaller, deprecated layout struct,
+ * nand_ecclayout_user. This is necessary only to suppport the deprecated
+ * API ioctl ECCGETLAYOUT while allowing all new functionality to use
+ * nand_ecclayout flexibly (i.e. the struct may change size in new
+ * releases without requiring major rewrites).
+ */
+static int shrink_ecclayout(const struct nand_ecclayout *from,
+                struct nand_ecclayout_user *to)
+{
+        int i;
+
+        if (!from || !to)
+                return -EINVAL;
+
+        memset(to, 0, sizeof(*to));
+
+        to->eccbytes = min((int)from->eccbytes, MTD_MAX_ECCPOS_ENTRIES_OLD);
+        for (i = 0; i < to->eccbytes; i++)
+                to->eccpos[i] = from->eccpos[i];
+
+        for (i = 0; i < MTD_MAX_OOBFREE_ENTRIES; i++) {
+                if (from->oobfree[i].length == 0 &&
+                                from->oobfree[i].offset == 0)
+                        break;
+                to->oobavail += from->oobfree[i].length;
+                to->oobfree[i] = from->oobfree[i];
+        }
+
+        return 0;
+}
+
 static int mtd_ioctl(struct file *file, u_int cmd, u_long arg)
 {
         struct mtd_file_info *mfi = file->private_data;
@@ -812,14 +845,23 @@ static int mtd_ioctl(struct file *file, u_int cmd, u_long arg)
         }
 #endif
 
+        /* This ioctl is being deprecated - it truncates the ecc layout */
         case ECCGETLAYOUT:
         {
+                struct nand_ecclayout_user *usrlay;
+
                 if (!mtd->ecclayout)
                         return -EOPNOTSUPP;
 
-                if (copy_to_user(argp, mtd->ecclayout,
-                                 sizeof(struct nand_ecclayout)))
-                        return -EFAULT;
+                usrlay = kmalloc(sizeof(*usrlay), GFP_KERNEL);
+                if (!usrlay)
+                        return -ENOMEM;
+
+                shrink_ecclayout(mtd->ecclayout, usrlay);
+
+                if (copy_to_user(argp, usrlay, sizeof(*usrlay)))
+                        ret = -EFAULT;
+                kfree(usrlay);
                 break;
         }
 
diff --git a/drivers/mtd/nand/davinci_nand.c b/drivers/mtd/nand/davinci_nand.c
index 2ac7367afe7..70698e86e43 100644
--- a/drivers/mtd/nand/davinci_nand.c
+++ b/drivers/mtd/nand/davinci_nand.c
@@ -749,6 +749,9 @@ static int __init nand_davinci_probe(struct platform_device *pdev)
                  * breaks userspace ioctl interface with mtd-utils. Once we
                  * resolve this issue, NAND_ECC_HW_OOB_FIRST mode can be used
                  * for the 4KiB page chips.
+                 *
+                 * TODO: Note that nand_ecclayout has now been expanded and can
+                 *  hold plenty of OOB entries.
                  */
                 dev_warn(&pdev->dev, "no 4-bit ECC support yet "
                                 "for 4KiB-page NAND\n");
diff --git a/include/linux/mtd/mtd.h b/include/linux/mtd/mtd.h
index 8485e42a9b0..03a1e954c58 100644
--- a/include/linux/mtd/mtd.h
+++ b/include/linux/mtd/mtd.h
@@ -110,6 +110,21 @@ struct mtd_oob_ops {
         uint8_t         *oobbuf;
 };
 
+#define MTD_MAX_OOBFREE_ENTRIES_LARGE   32
+#define MTD_MAX_ECCPOS_ENTRIES_LARGE    448
+#define MTD_MAX_ECCPOS_ENTRIES_OLD      64      /* Previous maximum */
+/*
+ * Correct ECC layout control structure. This replaces old nand_ecclayout
+ * (mtd-abi.h) that is exported via ECCGETLAYOUT ioctl. It should be expandable
+ *  in the future simply by the above macros.
+ */
+struct nand_ecclayout {
+        __u32 eccbytes;
+        __u32 eccpos[MTD_MAX_ECCPOS_ENTRIES_LARGE];
+        __u32 oobavail;
+        struct nand_oobfree oobfree[MTD_MAX_OOBFREE_ENTRIES_LARGE];
+};
+
 struct mtd_info {
         u_char type;
         uint32_t flags;
diff --git a/include/linux/mtd/partitions.h b/include/linux/mtd/partitions.h
index 274b6196091..930c8ac198d 100644
--- a/include/linux/mtd/partitions.h
+++ b/include/linux/mtd/partitions.h
@@ -39,7 +39,7 @@ struct mtd_partition {
         uint64_t size;                  /* partition size */
         uint64_t offset;                /* offset within the master MTD space */
         uint32_t mask_flags;            /* master MTD flags to mask out for this partition */
-        struct nand_ecclayout *ecclayout;       /* out of band layout for this partition (NAND only)*/
+        struct nand_ecclayout *ecclayout;       /* out of band layout for this partition (NAND only) */
 };
 
 #define MTDPART_OFS_NXTBLK      (-2)
diff --git a/include/mtd/mtd-abi.h b/include/mtd/mtd-abi.h
index 4debb451463..5bce0838434 100644
--- a/include/mtd/mtd-abi.h
+++ b/include/mtd/mtd-abi.h
@@ -119,7 +119,7 @@ struct otp_info {
 #define OTPGETREGIONCOUNT       _IOW('M', 14, int)
 #define OTPGETREGIONINFO        _IOW('M', 15, struct otp_info)
 #define OTPLOCK                 _IOR('M', 16, struct otp_info)
-#define ECCGETLAYOUT            _IOR('M', 17, struct nand_ecclayout)
+#define ECCGETLAYOUT            _IOR('M', 17, struct nand_ecclayout_user)
 #define ECCGETSTATS             _IOR('M', 18, struct mtd_ecc_stats)
 #define MTDFILEMODE             _IO('M', 19)
 #define MEMERASE64              _IOW('M', 20, struct erase_info_user64)
@@ -148,7 +148,7 @@ struct nand_oobfree {
  * ECC layout control structure. Exported to userspace for
  * diagnosis and to allow creation of raw images
  */
-struct nand_ecclayout {
+struct nand_ecclayout_user {
         __u32 eccbytes;
         __u32 eccpos[64];
         __u32 oobavail;
diff --git a/include/mtd/mtd-user.h b/include/mtd/mtd-user.h
index aa3c2f86a91..83327c808c8 100644
--- a/include/mtd/mtd-user.h
+++ b/include/mtd/mtd-user.h
@@ -29,6 +29,6 @@ typedef struct mtd_info_user mtd_info_t;
 typedef struct erase_info_user erase_info_t;
 typedef struct region_info_user region_info_t;
 typedef struct nand_oobinfo nand_oobinfo_t;
-typedef struct nand_ecclayout nand_ecclayout_t;
+typedef struct nand_ecclayout_user nand_ecclayout_t;
 
 #endif /* __MTD_USER_H__ */