UBI: fastmap: fix backward compatibility with image_seq

Some old UBI implementations (e.g. U-Boot) have not implemented the image
sequence feature.
So, when erase blocks are written, the image sequence in the ec header
is lost (set to zero).
UBI scan_all() takes this case into account (commits
32bc4820287a1a03982979515949e8ea56eac641 and
2eadaad67b2b6bd132eda105128d2d466298b8e3)

But fastmap scan functions (ubi_scan_fastmap() and scan_pool()) didn't.

This patch fixes the issue.

Signed-off-by: Richard Genoud <richard.genoud@gmail.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>

diff --git a/drivers/mtd/ubi/fastmap.c b/drivers/mtd/ubi/fastmap.c
index 9b42add0553c223f4ee92142cba9b39549260797..05067f522476a7709b44c488c578954328d35784 100644 (file)
--- a/drivers/mtd/ubi/fastmap.c
+++ b/drivers/mtd/ubi/fastmap.c
@@ -407,6 +407,7 @@ static int scan_pool(struct ubi_device *ubi, struct ubi_attach_info *ai,
         */
        for (i = 0; i < pool_size; i++) {
                int scrub = 0;
+               int image_seq;
 
                pnum = be32_to_cpu(pebs[i]);
 
@@ -425,7 +426,13 @@ static int scan_pool(struct ubi_device *ubi, struct ubi_attach_info *ai,
                } else if (ret == UBI_IO_BITFLIPS)
                        scrub = 1;
 
-               if (be32_to_cpu(ech->image_seq) != ubi->image_seq) {
+               /*
+                * Older UBI implementations have image_seq set to zero, so
+                * we shouldn't fail if image_seq == 0.
+                */
+               image_seq = be32_to_cpu(ech->image_seq);
+
+               if (image_seq && (image_seq != ubi->image_seq)) {
                        ubi_err("bad image seq: 0x%x, expected: 0x%x",
                                be32_to_cpu(ech->image_seq), ubi->image_seq);
                        ret = UBI_BAD_FASTMAP;
@@ -923,6 +930,8 @@ int ubi_scan_fastmap(struct ubi_device *ubi, struct ubi_attach_info *ai,
        }
 
        for (i = 0; i < used_blocks; i++) {
+               int image_seq;
+
                pnum = be32_to_cpu(fmsb->block_loc[i]);
 
                if (ubi_io_is_bad(ubi, pnum)) {
@@ -940,10 +949,17 @@ int ubi_scan_fastmap(struct ubi_device *ubi, struct ubi_attach_info *ai,
                } else if (ret == UBI_IO_BITFLIPS)
                        fm->to_be_tortured[i] = 1;
 
+               image_seq = be32_to_cpu(ech->image_seq);
                if (!ubi->image_seq)
-                       ubi->image_seq = be32_to_cpu(ech->image_seq);
+                       ubi->image_seq = image_seq;
 
-               if (be32_to_cpu(ech->image_seq) != ubi->image_seq) {
+               /*
+                * Older UBI implementations have image_seq set to zero, so
+                * we shouldn't fail if image_seq == 0.
+                */
+               if (image_seq && (image_seq != ubi->image_seq)) {
+                       ubi_err("wrong image seq:%d instead of %d",
+                               be32_to_cpu(ech->image_seq), ubi->image_seq);
                        ret = UBI_BAD_FASTMAP;
                        goto free_hdr;
                }