ubi: Rework Fastmap attach base code

Introduce a new list to the UBI attach information
object to be able to deal better with old and corrupted
Fastmap eraseblocks.
Also move more Fastmap specific code into fastmap.c.

Signed-off-by: Richard Weinberger <richard@nod.at>

1 files changed, 33 insertions, 3 deletions

diff --git a/drivers/mtd/ubi/fastmap.c b/drivers/mtd/ubi/fastmap.c
index ab337e67e1f3..12bdb0902327 100644
--- a/drivers/mtd/ubi/fastmap.c
+++ b/drivers/mtd/ubi/fastmap.c
@@ -850,27 +850,57 @@ fail:
 }
 
 /**
+ * find_fm_anchor - find the most recent Fastmap superblock (anchor)
+ * @ai: UBI attach info to be filled
+ */
+static int find_fm_anchor(struct ubi_attach_info *ai)
+{
+        int ret = -1;
+        struct ubi_ainf_peb *aeb;
+        unsigned long long max_sqnum = 0;
+
+        list_for_each_entry(aeb, &ai->fastmap, u.list) {
+                if (aeb->vol_id == UBI_FM_SB_VOLUME_ID && aeb->sqnum > max_sqnum) {
+                        max_sqnum = aeb->sqnum;
+                        ret = aeb->pnum;
+                }
+        }
+
+        return ret;
+}
+
+/**
  * ubi_scan_fastmap - scan the fastmap.
  * @ubi: UBI device object
  * @ai: UBI attach info to be filled
- * @fm_anchor: The fastmap starts at this PEB
+ * @scan_ai: UBI attach info from the first 64 PEBs,
+ *           used to find the most recent Fastmap data structure
  *
  * Returns 0 on success, UBI_NO_FASTMAP if no fastmap was found,
  * UBI_BAD_FASTMAP if one was found but is not usable.
  * < 0 indicates an internal error.
  */
 int ubi_scan_fastmap(struct ubi_device *ubi, struct ubi_attach_info *ai,
-                     int fm_anchor)
+                     struct ubi_attach_info *scan_ai)
 {
         struct ubi_fm_sb *fmsb, *fmsb2;
         struct ubi_vid_hdr *vh;
         struct ubi_ec_hdr *ech;
         struct ubi_fastmap_layout *fm;
-        int i, used_blocks, pnum, ret = 0;
+        struct ubi_ainf_peb *tmp_aeb, *aeb;
+        int i, used_blocks, pnum, fm_anchor, ret = 0;
         size_t fm_size;
         __be32 crc, tmp_crc;
         unsigned long long sqnum = 0;
 
+        fm_anchor = find_fm_anchor(scan_ai);
+        if (fm_anchor < 0)
+                return UBI_NO_FASTMAP;
+
+        /* Move all (possible) fastmap blocks into our new attach structure. */
+        list_for_each_entry_safe(aeb, tmp_aeb, &scan_ai->fastmap, u.list)
+                list_move_tail(&aeb->u.list, &ai->fastmap);
+
         down_write(&ubi->fm_protect);
         memset(ubi->fm_buf, 0, ubi->fm_size);