4 files changed, 67 insertions, 24 deletions

diff --git a/drivers/mtd/ubi/build.c b/drivers/mtd/ubi/build.c
index 5ebe280225d6..f49e49dc5928 100644
--- a/drivers/mtd/ubi/build.c
+++ b/drivers/mtd/ubi/build.c
@@ -672,7 +672,33 @@ static int io_init(struct ubi_device *ubi)
 		ubi->nor_flash = 1;
 	}
 
-	ubi->min_io_size = ubi->mtd->writesize;
+	/*
+	 * Set UBI min. I/O size (@ubi->min_io_size). We use @mtd->writebufsize
+	 * for these purposes, not @mtd->writesize. At the moment this does not
+	 * matter for NAND, because currently @mtd->writebufsize is equivalent to
+	 * @mtd->writesize for all NANDs. However, some CFI NOR flashes may
+	 * have @mtd->writebufsize which is multiple of @mtd->writesize.
+	 *
+	 * The reason we use @mtd->writebufsize for @ubi->min_io_size is that
+	 * UBI and UBIFS recovery algorithms rely on the fact that if there was
+	 * an unclean power cut, then we can find offset of the last corrupted
+	 * node, align the offset to @ubi->min_io_size, read the rest of the
+	 * eraseblock starting from this offset, and check whether there are
+	 * only 0xFF bytes. If yes, then we are probably dealing with a
+	 * corruption caused by a power cut, if not, then this is probably some
+	 * severe corruption.
+	 *
+	 * Thus, we have to use the maximum write unit size of the flash, which
+	 * is @mtd->writebufsize, because @mtd->writesize is the minimum write
+	 * size, not the maximum.
+	 */
+	if (ubi->mtd->type == MTD_NANDFLASH)
+		ubi_assert(ubi->mtd->writebufsize == ubi->mtd->writesize);
+	else if (ubi->mtd->type == MTD_NORFLASH)
+		ubi_assert(ubi->mtd->writebufsize % ubi->mtd->writesize == 0);
+
+	ubi->min_io_size = ubi->mtd->writebufsize;
+
 	ubi->hdrs_min_io_size = ubi->mtd->writesize >> ubi->mtd->subpage_sft;
 
 	/*
diff --git a/drivers/mtd/ubi/io.c b/drivers/mtd/ubi/io.c
index c2960ac9f39c..811775aa8ee8 100644
--- a/drivers/mtd/ubi/io.c
+++ b/drivers/mtd/ubi/io.c
@@ -482,10 +482,17 @@ static int nor_erase_prepare(struct ubi_device *ubi, int pnum)
 	uint32_t data = 0;
 	struct ubi_vid_hdr vid_hdr;
 
-	addr = (loff_t)pnum * ubi->peb_size + ubi->vid_hdr_aloffset;
+	/*
+	 * It is important to first invalidate the EC header, and then the VID
+	 * header. Otherwise a power cut may lead to valid EC header and
+	 * invalid VID header, in which case UBI will treat this PEB as
+	 * corrupted and will try to preserve it, and print scary warnings (see
+	 * the header comment in scan.c for more information).
+	 */
+	addr = (loff_t)pnum * ubi->peb_size;
 	err = ubi->mtd->write(ubi->mtd, addr, 4, &written, (void *)&data);
 	if (!err) {
-		addr -= ubi->vid_hdr_aloffset;
+		addr += ubi->vid_hdr_aloffset;
 		err = ubi->mtd->write(ubi->mtd, addr, 4, &written,
 				      (void *)&data);
 		if (!err)
@@ -494,18 +501,24 @@ static int nor_erase_prepare(struct ubi_device *ubi, int pnum)
 
 	/*
 	 * We failed to write to the media. This was observed with Spansion
-	 * S29GL512N NOR flash. Most probably the eraseblock erasure was
-	 * interrupted at a very inappropriate moment, so it became unwritable.
-	 * In this case we probably anyway have garbage in this PEB.
+	 * S29GL512N NOR flash. Most probably the previously eraseblock erasure
+	 * was interrupted at a very inappropriate moment, so it became
+	 * unwritable. 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_EBADMSG || 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
-		 * case of an unclean reboot.
-		 */
-		return 0;
+	if (err1 == UBI_IO_BAD_HDR_EBADMSG || err1 == UBI_IO_BAD_HDR) {
+		struct ubi_ec_hdr ec_hdr;
+
+		err1 = ubi_io_read_ec_hdr(ubi, pnum, &ec_hdr, 0);
+		if (err1 == UBI_IO_BAD_HDR_EBADMSG || err1 == UBI_IO_BAD_HDR)
+			/*
+			 * Both VID and EC headers are corrupted, so we can
+			 * safely erase this PEB and not afraid that it will be
+			 * treated as a valid PEB in case of an unclean reboot.
+			 */
+			return 0;
+	}
 
 	/*
 	 * The PEB contains a valid VID header, but we cannot invalidate it.
diff --git a/drivers/mtd/ubi/scan.c b/drivers/mtd/ubi/scan.c
index 3c631863bf40..79ca304fc4db 100644
--- a/drivers/mtd/ubi/scan.c
+++ b/drivers/mtd/ubi/scan.c
@@ -787,16 +787,15 @@ static int check_corruption(struct ubi_device *ubi, struct ubi_vid_hdr *vid_hdr,
 		 * erased, so it became unstable and corrupted, and should be
 		 * erased.
 		 */
-		return 0;
+		err = 0;
+		goto out_unlock;
 	}
 
 	if (err)
-		return err;
+		goto out_unlock;
 
-	if (ubi_check_pattern(ubi->peb_buf1, 0xFF, ubi->leb_size)) {
-		mutex_unlock(&ubi->buf_mutex);
-		return 0;
-	}
+	if (ubi_check_pattern(ubi->peb_buf1, 0xFF, ubi->leb_size))
+		goto out_unlock;
 
 	ubi_err("PEB %d contains corrupted VID header, and the data does not "
 		"contain all 0xFF, this may be a non-UBI PEB or a severe VID "
@@ -806,8 +805,11 @@ static int check_corruption(struct ubi_device *ubi, struct ubi_vid_hdr *vid_hdr,
 		pnum, ubi->leb_start, ubi->leb_size);
 	ubi_dbg_print_hex_dump(KERN_DEBUG, "", DUMP_PREFIX_OFFSET, 32, 1,
 			       ubi->peb_buf1, ubi->leb_size, 1);
+	err = 1;
+
+out_unlock:
 	mutex_unlock(&ubi->buf_mutex);
-	return 1;
+	return err;
 }
 
 /**
@@ -951,6 +953,10 @@ static int process_eb(struct ubi_device *ubi, struct ubi_scan_info *si,
 			 * impossible to distinguish it from a PEB which just
 			 * contains garbage because of a power cut during erase
 			 * operation. So we just schedule this PEB for erasure.
+			 *
+			 * Besides, in case of NOR flash, we deliberatly
+			 * corrupt both headers because NOR flash erasure is
+			 * slow and can start from the end.
 			 */
 			err = 0;
 		else
diff --git a/drivers/mtd/ubi/vtbl.c b/drivers/mtd/ubi/vtbl.c
index fcdb7f65fe0b..0b8141fc5c26 100644
--- a/drivers/mtd/ubi/vtbl.c
+++ b/drivers/mtd/ubi/vtbl.c
@@ -425,12 +425,11 @@ static struct ubi_vtbl_record *process_lvol(struct ubi_device *ubi,
 
 	/* Read both LEB 0 and LEB 1 into memory */
 	ubi_rb_for_each_entry(rb, seb, &sv->root, u.rb) {
-		leb[seb->lnum] = vmalloc(ubi->vtbl_size);
+		leb[seb->lnum] = vzalloc(ubi->vtbl_size);
 		if (!leb[seb->lnum]) {
 			err = -ENOMEM;
 			goto out_free;
 		}
-		memset(leb[seb->lnum], 0, ubi->vtbl_size);
 
 		err = ubi_io_read_data(ubi, leb[seb->lnum], seb->pnum, 0,
 				       ubi->vtbl_size);
@@ -516,10 +515,9 @@ static struct ubi_vtbl_record *create_empty_lvol(struct ubi_device *ubi,
 	int i;
 	struct ubi_vtbl_record *vtbl;
 
-	vtbl = vmalloc(ubi->vtbl_size);
+	vtbl = vzalloc(ubi->vtbl_size);
 	if (!vtbl)
 		return ERR_PTR(-ENOMEM);
-	memset(vtbl, 0, ubi->vtbl_size);
 
 	for (i = 0; i < ubi->vtbl_slots; i++)
 		memcpy(&vtbl[i], &empty_vtbl_record, UBI_VTBL_RECORD_SIZE);