1 files changed, 89 insertions, 1 deletions

diff --git a/drivers/mtd/ubi/eba.c b/drivers/mtd/ubi/eba.c
index 250e30fac61b..593a4f9d97e3 100644
--- a/drivers/mtd/ubi/eba.c
+++ b/drivers/mtd/ubi/eba.c
@@ -490,6 +490,82 @@ out_unlock:
         return err;
 }
 
+#ifdef CONFIG_MTD_UBI_FASTMAP
+/**
+ * check_mapping - check and fixup a mapping
+ * @ubi: UBI device description object
+ * @vol: volume description object
+ * @lnum: logical eraseblock number
+ * @pnum: physical eraseblock number
+ *
+ * Checks whether a given mapping is valid. Fastmap cannot track LEB unmap
+ * operations, if such an operation is interrupted the mapping still looks
+ * good, but upon first read an ECC is reported to the upper layer.
+ * Normaly during the full-scan at attach time this is fixed, for Fastmap
+ * we have to deal with it while reading.
+ * If the PEB behind a LEB shows this symthom we change the mapping to
+ * %UBI_LEB_UNMAPPED and schedule the PEB for erasure.
+ *
+ * Returns 0 on success, negative error code in case of failure.
+ */
+static int check_mapping(struct ubi_device *ubi, struct ubi_volume *vol, int lnum,
+                         int *pnum)
+{
+        int err;
+        struct ubi_vid_io_buf *vidb;
+
+        if (!ubi->fast_attach)
+                return 0;
+
+        vidb = ubi_alloc_vid_buf(ubi, GFP_NOFS);
+        if (!vidb)
+                return -ENOMEM;
+
+        err = ubi_io_read_vid_hdr(ubi, *pnum, vidb, 0);
+        if (err > 0 && err != UBI_IO_BITFLIPS) {
+                int torture = 0;
+
+                switch (err) {
+                        case UBI_IO_FF:
+                        case UBI_IO_FF_BITFLIPS:
+                        case UBI_IO_BAD_HDR:
+                        case UBI_IO_BAD_HDR_EBADMSG:
+                                break;
+                        default:
+                                ubi_assert(0);
+                }
+
+                if (err == UBI_IO_BAD_HDR_EBADMSG || err == UBI_IO_FF_BITFLIPS)
+                        torture = 1;
+
+                down_read(&ubi->fm_eba_sem);
+                vol->eba_tbl->entries[lnum].pnum = UBI_LEB_UNMAPPED;
+                up_read(&ubi->fm_eba_sem);
+                ubi_wl_put_peb(ubi, vol->vol_id, lnum, *pnum, torture);
+
+                *pnum = UBI_LEB_UNMAPPED;
+        } else if (err < 0) {
+                ubi_err(ubi, "unable to read VID header back from PEB %i: %i",
+                        *pnum, err);
+
+                goto out_free;
+        }
+
+        err = 0;
+
+out_free:
+        ubi_free_vid_buf(vidb);
+
+        return err;
+}
+#else
+static int check_mapping(struct ubi_device *ubi, struct ubi_volume *vol, int lnum,
+                  int *pnum)
+{
+        return 0;
+}
+#endif
+
 /**
  * ubi_eba_read_leb - read data.
  * @ubi: UBI device description object
@@ -522,7 +598,13 @@ int ubi_eba_read_leb(struct ubi_device *ubi, struct ubi_volume *vol, int lnum,
                 return err;
 
         pnum = vol->eba_tbl->entries[lnum].pnum;
-        if (pnum < 0) {
+        if (pnum >= 0) {
+                err = check_mapping(ubi, vol, lnum, &pnum);
+                if (err < 0)
+                        goto out_unlock;
+        }
+
+        if (pnum == UBI_LEB_UNMAPPED) {
                 /*
                  * The logical eraseblock is not mapped, fill the whole buffer
                  * with 0xFF bytes. The exception is static volumes for which
@@ -931,6 +1013,12 @@ int ubi_eba_write_leb(struct ubi_device *ubi, struct ubi_volume *vol, int lnum,
 
         pnum = vol->eba_tbl->entries[lnum].pnum;
         if (pnum >= 0) {
+                err = check_mapping(ubi, vol, lnum, &pnum);
+                if (err < 0)
+                        goto out;
+        }
+
+        if (pnum >= 0) {
                 dbg_eba("write %d bytes at offset %d of LEB %d:%d, PEB %d",
                         len, offset, vol_id, lnum, pnum);