UBI: introduce a new IO return code

This patch introduces the %UBI_IO_BAD_HDR_READ return code for
the I/O level function. We will use this code in order to distinguish
between "corrupted header possibly because this is non-ubi data" and
"corrupted header possibly because of real data corruption and ECC error".

So far this patch does not introduce any functional change, just a
preparation.

This patch is pased on a patch from
Sebastian Andrzej Siewior <sebastian@breakpoint.cc>

Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
Reviewed-by: Sebastian Andrzej Siewior <sebastian@breakpoint.cc>
Tested-by: Sebastian Andrzej Siewior <sebastian@breakpoint.cc>

4 files changed, 31 insertions, 23 deletions

diff --git a/drivers/mtd/ubi/eba.c b/drivers/mtd/ubi/eba.c
index 8e8226744320..b582671ca3a0 100644
--- a/drivers/mtd/ubi/eba.c
+++ b/drivers/mtd/ubi/eba.c
@@ -418,7 +418,8 @@ retry:
                                  * may try to recover data. FIXME: but this is
                                  * not implemented.
                                  */
-                                if (err == UBI_IO_BAD_HDR) {
+                                if (err == UBI_IO_BAD_HDR_READ ||
+                                    err == UBI_IO_BAD_HDR) {
                                         ubi_warn("corrupted VID header at PEB "
                                                  "%d, LEB %d:%d", pnum, vol_id,
                                                  lnum);
@@ -962,7 +963,7 @@ write_error:
 static int is_error_sane(int err)
 {
         if (err == -EIO || err == -ENOMEM || err == UBI_IO_BAD_HDR ||
-            err == -ETIMEDOUT)
+            err == UBI_IO_BAD_HDR_READ || err == -ETIMEDOUT)
                 return 0;
         return 1;
 }
diff --git a/drivers/mtd/ubi/io.c b/drivers/mtd/ubi/io.c
index 02b19327dcc4..b812f8805367 100644
--- a/drivers/mtd/ubi/io.c
+++ b/drivers/mtd/ubi/io.c
@@ -515,7 +515,7 @@ static int nor_erase_prepare(struct ubi_device *ubi, int pnum)
          * In this case we probably anyway have garbage in this PEB.
          */
         err1 = ubi_io_read_vid_hdr(ubi, pnum, &vid_hdr, 0);
-        if (err1 == UBI_IO_BAD_HDR)
+        if (err1 == UBI_IO_BAD_HDR_READ || err1 == UBI_IO_BAD_HDR)
                 /*
                  * The VID header is corrupted, so we can safely erase this
                  * PEB and not afraid that it will be treated as a valid PEB in
@@ -736,23 +736,21 @@ int ubi_io_read_ec_hdr(struct ubi_device *ubi, int pnum,
                  * header is still OK, we just report this as there was a
                  * bit-flip.
                  */
-                read_err = err;
+                if (err == -EBADMSG)
+                        read_err = UBI_IO_BAD_HDR_READ;
         }
 
         magic = be32_to_cpu(ec_hdr->magic);
         if (magic != UBI_EC_HDR_MAGIC) {
+                if (read_err)
+                        return read_err;
+
                 /*
                  * The magic field is wrong. Let's check if we have read all
                  * 0xFF. If yes, this physical eraseblock is assumed to be
                  * empty.
-                 *
-                 * But if there was a read error, we do not test it for all
-                 * 0xFFs. Even if it does contain all 0xFFs, this error
-                 * indicates that something is still wrong with this physical
-                 * eraseblock and we anyway cannot treat it as empty.
                  */
-                if (read_err != -EBADMSG &&
-                    check_pattern(ec_hdr, 0xFF, UBI_EC_HDR_SIZE)) {
+                if (check_pattern(ec_hdr, 0xFF, UBI_EC_HDR_SIZE)) {
                         /* The physical eraseblock is supposedly empty */
                         if (verbose)
                                 ubi_warn("no EC header found at PEB %d, "
@@ -788,7 +786,7 @@ int ubi_io_read_ec_hdr(struct ubi_device *ubi, int pnum,
                 } else if (UBI_IO_DEBUG)
                         dbg_msg("bad EC header CRC at PEB %d, calculated "
                                 "%#08x, read %#08x", pnum, crc, hdr_crc);
-                return UBI_IO_BAD_HDR;
+                return read_err ?: UBI_IO_BAD_HDR;
         }
 
         /* And of course validate what has just been read from the media */
@@ -798,6 +796,10 @@ int ubi_io_read_ec_hdr(struct ubi_device *ubi, int pnum,
                 return -EINVAL;
         }
 
+        /*
+         * If there was %-EBADMSG, but the header CRC is still OK, report about
+         * a bit-flip to force scrubbing on this PEB.
+         */
         return read_err ? UBI_IO_BITFLIPS : 0;
 }
 
@@ -1008,22 +1010,20 @@ int ubi_io_read_vid_hdr(struct ubi_device *ubi, int pnum,
                  * CRC check-sum and we will identify this. If the VID header is
                  * still OK, we just report this as there was a bit-flip.
                  */
-                read_err = err;
+                if (err == -EBADMSG)
+                        read_err = UBI_IO_BAD_HDR_READ;
         }
 
         magic = be32_to_cpu(vid_hdr->magic);
         if (magic != UBI_VID_HDR_MAGIC) {
+                if (read_err)
+                        return read_err;
+
                 /*
                  * If we have read all 0xFF bytes, the VID header probably does
                  * not exist and the physical eraseblock is assumed to be free.
-                 *
-                 * But if there was a read error, we do not test the data for
-                 * 0xFFs. Even if it does contain all 0xFFs, this error
-                 * indicates that something is still wrong with this physical
-                 * eraseblock and it cannot be regarded as free.
                  */
-                if (read_err != -EBADMSG &&
-                    check_pattern(vid_hdr, 0xFF, UBI_VID_HDR_SIZE)) {
+                if (check_pattern(vid_hdr, 0xFF, UBI_VID_HDR_SIZE)) {
                         /* The physical eraseblock is supposedly free */
                         if (verbose)
                                 ubi_warn("no VID header found at PEB %d, "
@@ -1059,7 +1059,7 @@ int ubi_io_read_vid_hdr(struct ubi_device *ubi, int pnum,
                 } else if (UBI_IO_DEBUG)
                         dbg_msg("bad CRC at PEB %d, calculated %#08x, "
                                 "read %#08x", pnum, crc, hdr_crc);
-                return UBI_IO_BAD_HDR;
+                return read_err ?: UBI_IO_BAD_HDR;
         }
 
         /* Validate the VID header that we have just read */
@@ -1069,6 +1069,10 @@ int ubi_io_read_vid_hdr(struct ubi_device *ubi, int pnum,
                 return -EINVAL;
         }
 
+        /*
+         * If there was a read error (%-EBADMSG), but the header CRC is still
+         * OK, report about a bit-flip to force scrubbing on this PEB.
+         */
         return read_err ? UBI_IO_BITFLIPS : 0;
 }
 
diff --git a/drivers/mtd/ubi/scan.c b/drivers/mtd/ubi/scan.c
index b878a7661f5a..c45900744107 100644
--- a/drivers/mtd/ubi/scan.c
+++ b/drivers/mtd/ubi/scan.c
@@ -745,7 +745,7 @@ static int process_eb(struct ubi_device *ubi, struct ubi_scan_info *si,
                 bitflips = 1;
         else if (err == UBI_IO_PEB_EMPTY)
                 return add_to_list(si, pnum, UBI_SCAN_UNKNOWN_EC, &si->erase);
-        else if (err == UBI_IO_BAD_HDR) {
+        else if (err == UBI_IO_BAD_HDR_READ || err == UBI_IO_BAD_HDR) {
                 /*
                  * We have to also look at the VID header, possibly it is not
                  * corrupted. Set %bitflips flag in order to make this PEB be
@@ -813,7 +813,7 @@ static int process_eb(struct ubi_device *ubi, struct ubi_scan_info *si,
                 return err;
         else if (err == UBI_IO_BITFLIPS)
                 bitflips = 1;
-        else if (err == UBI_IO_BAD_HDR ||
+        else if (err == UBI_IO_BAD_HDR_READ || err == UBI_IO_BAD_HDR ||
                  (err == UBI_IO_PEB_FREE && ec_corr)) {
                 /* VID header is corrupted */
                 err = add_to_list(si, pnum, ec, &si->corr);
diff --git a/drivers/mtd/ubi/ubi.h b/drivers/mtd/ubi/ubi.h
index 539b3f6c7a56..0359e0cce482 100644
--- a/drivers/mtd/ubi/ubi.h
+++ b/drivers/mtd/ubi/ubi.h
@@ -90,12 +90,15 @@
  * UBI_IO_PEB_FREE: the physical eraseblock is free, i.e. it contains only a
  *                  valid erase counter header, and the rest are %0xFF bytes
  * UBI_IO_BAD_HDR: the EC or VID header is corrupted (bad magic or CRC)
+ * UBI_IO_BAD_HDR_READ: the same as %UBI_IO_BAD_HDR, but also there was a read
+ *                      error reported by the flash driver
  * UBI_IO_BITFLIPS: bit-flips were detected and corrected
  */
 enum {
         UBI_IO_PEB_EMPTY = 1,
         UBI_IO_PEB_FREE,
         UBI_IO_BAD_HDR,
+        UBI_IO_BAD_HDR_READ,
         UBI_IO_BITFLIPS
 };