Merge branch 'linux-next' of git://git.infradead.org/ubi-2.6

* 'linux-next' of git://git.infradead.org/ubi-2.6:
UBI: do not warn unnecessarily
UBI: do not print message about corruptes PEBs if we have none of them
UBI: improve delete-compatible volumes handling
UBI: fix error message and compilation warnings
UBI: generate random image_seq when formatting MTD devices
UBI: improve ECC error message
UBI: improve corrupted flash handling
UBI: introduce eraseblock counter variables
UBI: introduce a new IO return code
UBI: simplify IO error codes

drivers/mtd/ubi/build.c

···
 	ubi->good_peb_count = ubi->peb_count - ubi->bad_peb_count;
 	ubi->max_ec = si->max_ec;
 	ubi->mean_ec = si->mean_ec;
+	ubi_msg("max. sequence number:       %llu", si->max_sqnum);
 
 	err = ubi_read_volume_table(ubi, si);
 	if (err)
···
 	ubi_msg("number of PEBs reserved for bad PEB handling: %d",
 		ubi->beb_rsvd_pebs);
 	ubi_msg("max/mean erase counter: %d/%d", ubi->max_ec, ubi->mean_ec);
-	ubi_msg("image sequence number: %d", ubi->image_seq);
+	ubi_msg("image sequence number:  %d", ubi->image_seq);
 
 	/*
 	 * The below lock makes sure we do not race with 'ubi_thread()' which

drivers/mtd/ubi/eba.c

···
 				 * may try to recover data. FIXME: but this is
 				 * not implemented.
 				 */
-				if (err == UBI_IO_BAD_VID_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);
···
  */
 static int is_error_sane(int err)
 {
-	if (err == -EIO || err == -ENOMEM || err == UBI_IO_BAD_VID_HDR ||
-	    err == -ETIMEDOUT)
+	if (err == -EIO || err == -ENOMEM || err == UBI_IO_BAD_HDR ||
+	    err == UBI_IO_BAD_HDR_READ || err == -ETIMEDOUT)
 		return 0;
 	return 1;
 }
···
 }
 
 /**
+ * print_rsvd_warning - warn about not having enough reserved PEBs.
+ * @ubi: UBI device description object
+ *
+ * This is a helper function for 'ubi_eba_init_scan()' which is called when UBI
+ * cannot reserve enough PEBs for bad block handling. This function makes a
+ * decision whether we have to print a warning or not. The algorithm is as
+ * follows:
+ *   o if this is a new UBI image, then just print the warning
+ *   o if this is an UBI image which has already been used for some time, print
+ *     a warning only if we can reserve less than 10% of the expected amount of
+ *     the reserved PEB.
+ *
+ * The idea is that when UBI is used, PEBs become bad, and the reserved pool
+ * of PEBs becomes smaller, which is normal and we do not want to scare users
+ * with a warning every time they attach the MTD device. This was an issue
+ * reported by real users.
+ */
+static void print_rsvd_warning(struct ubi_device *ubi,
+			       struct ubi_scan_info *si)
+{
+	/*
+	 * The 1 << 18 (256KiB) number is picked randomly, just a reasonably
+	 * large number to distinguish between newly flashed and used images.
+	 */
+	if (si->max_sqnum > (1 << 18)) {
+		int min = ubi->beb_rsvd_level / 10;
+
+		if (!min)
+			min = 1;
+		if (ubi->beb_rsvd_pebs > min)
+			return;
+	}
+
+	ubi_warn("cannot reserve enough PEBs for bad PEB handling, reserved %d,"
+		 " need %d", ubi->beb_rsvd_pebs, ubi->beb_rsvd_level);
+}
+
+/**
  * ubi_eba_init_scan - initialize the EBA sub-system using scanning information.
  * @ubi: UBI device description object
  * @si: scanning information
···
 		if (ubi->avail_pebs < ubi->beb_rsvd_level) {
 			/* No enough free physical eraseblocks */
 			ubi->beb_rsvd_pebs = ubi->avail_pebs;
-			ubi_warn("cannot reserve enough PEBs for bad PEB "
-				 "handling, reserved %d, need %d",
-				 ubi->beb_rsvd_pebs, ubi->beb_rsvd_level);
+			print_rsvd_warning(ubi, si);
 		} else
 			ubi->beb_rsvd_pebs = ubi->beb_rsvd_level;
 

drivers/mtd/ubi/io.c

···
 retry:
 	err = ubi->mtd->read(ubi->mtd, addr, len, &read, buf);
 	if (err) {
+		const char *errstr = (err == -EBADMSG) ? " (ECC error)" : "";
+
 		if (err == -EUCLEAN) {
 			/*
 			 * -EUCLEAN is reported if there was a bit-flip which
···
 		}
 
 		if (read != len && retries++ < UBI_IO_RETRIES) {
-			dbg_io("error %d while reading %d bytes from PEB %d:%d,"
+			dbg_io("error %d%s while reading %d bytes from PEB %d:%d,"
 			       " read only %zd bytes, retry",
-			       err, len, pnum, offset, read);
+			       err, errstr, len, pnum, offset, read);
 			yield();
 			goto retry;
 		}
 
-		ubi_err("error %d while reading %d bytes from PEB %d:%d, "
-			"read %zd bytes", err, len, pnum, offset, read);
+		ubi_err("error %d%s while reading %d bytes from PEB %d:%d, "
+			"read %zd bytes", err, errstr, len, pnum, offset, read);
 		ubi_dbg_dump_stack();
 
 		/*
···
 	 * 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_VID_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
···
  * o %UBI_IO_BITFLIPS if the CRC is correct, but bit-flips were detected
  *   and corrected by the flash driver; this is harmless but may indicate that
  *   this eraseblock may become bad soon (but may be not);
- * o %UBI_IO_BAD_EC_HDR if the erase counter header is corrupted (a CRC error);
+ * o %UBI_IO_BAD_HDR if the erase counter header is corrupted (a CRC error);
  * o %UBI_IO_PEB_EMPTY if the physical eraseblock is empty;
  * o a negative error code in case of failure.
  */
···
 		 * 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, "
···
 		} else if (UBI_IO_DEBUG)
 			dbg_msg("bad magic number at PEB %d: %08x instead of "
 				"%08x", pnum, magic, UBI_EC_HDR_MAGIC);
-		return UBI_IO_BAD_EC_HDR;
+		return UBI_IO_BAD_HDR;
 	}
 
 	crc = crc32(UBI_CRC32_INIT, ec_hdr, UBI_EC_HDR_SIZE_CRC);
···
 		} 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_EC_HDR;
+		return read_err ?: UBI_IO_BAD_HDR;
 	}
 
 	/* And of course validate what has just been read from the media */
···
 		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;
 }
 
···
  * o %UBI_IO_BITFLIPS if the CRC is correct, but bit-flips were detected
  *   and corrected by the flash driver; this is harmless but may indicate that
  *   this eraseblock may become bad soon;
- * o %UBI_IO_BAD_VID_HDR if the volume identifier header is corrupted (a CRC
+ * o %UBI_IO_BAD_HDR if the volume identifier header is corrupted (a CRC
  *   error detected);
  * o %UBI_IO_PEB_FREE if the physical eraseblock is free (i.e., there is no VID
  *   header there);
···
 		 * 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, "
···
 		} else if (UBI_IO_DEBUG)
 			dbg_msg("bad magic number at PEB %d: %08x instead of "
 				"%08x", pnum, magic, UBI_VID_HDR_MAGIC);
-		return UBI_IO_BAD_VID_HDR;
+		return UBI_IO_BAD_HDR;
 	}
 
 	crc = crc32(UBI_CRC32_INIT, vid_hdr, UBI_VID_HDR_SIZE_CRC);
···
 		} else if (UBI_IO_DEBUG)
 			dbg_msg("bad CRC at PEB %d, calculated %#08x, "
 				"read %#08x", pnum, crc, hdr_crc);
-		return UBI_IO_BAD_VID_HDR;
+		return read_err ?: UBI_IO_BAD_HDR;
 	}
 
 	/* Validate the VID header that we have just read */
···
 		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;
 }
 

drivers/mtd/ubi/scan.c

···
 #include <linux/slab.h>
 #include <linux/crc32.h>
 #include <linux/math64.h>
+#include <linux/random.h>
 #include "ubi.h"
 
 #ifdef CONFIG_MTD_UBI_DEBUG_PARANOID
···
 {
 	struct ubi_scan_leb *seb;
 
-	if (list == &si->free)
+	if (list == &si->free) {
 		dbg_bld("add to free: PEB %d, EC %d", pnum, ec);
-	else if (list == &si->erase)
+		si->free_peb_count += 1;
+	} else if (list == &si->erase) {
 		dbg_bld("add to erase: PEB %d, EC %d", pnum, ec);
-	else if (list == &si->corr) {
+		si->erase_peb_count += 1;
+	} else if (list == &si->corr) {
 		dbg_bld("add to corrupted: PEB %d, EC %d", pnum, ec);
-		si->corr_count += 1;
-	} else if (list == &si->alien)
+		si->corr_peb_count += 1;
+	} else if (list == &si->alien) {
 		dbg_bld("add to alien: PEB %d, EC %d", pnum, ec);
-	else
+		si->alien_peb_count += 1;
+	} else
 		BUG();
 
 	seb = kmalloc(sizeof(struct ubi_scan_leb), GFP_KERNEL);
···
 	sv->leb_count += 1;
 	rb_link_node(&seb->u.rb, parent, p);
 	rb_insert_color(&seb->u.rb, &sv->root);
+	si->used_peb_count += 1;
 	return 0;
 }
 
···
 		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_EC_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
 		 * moved and EC be re-created.
 		 */
-		ec_corr = 1;
+		ec_corr = err;
 		ec = UBI_SCAN_UNKNOWN_EC;
 		bitflips = 1;
 	}
-
-	si->is_empty = 0;
 
 	if (!ec_corr) {
 		int image_seq;
···
 		return err;
 	else if (err == UBI_IO_BITFLIPS)
 		bitflips = 1;
-	else if (err == UBI_IO_BAD_VID_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 */
+		if (err == UBI_IO_BAD_HDR_READ ||
+		    ec_corr == UBI_IO_BAD_HDR_READ)
+			si->read_err_count += 1;
 		err = add_to_list(si, pnum, ec, &si->corr);
 		if (err)
 			return err;
···
 		switch (vidh->compat) {
 		case UBI_COMPAT_DELETE:
 			ubi_msg("\"delete\" compatible internal volume %d:%d"
-				" found, remove it", vol_id, lnum);
+				" found, will remove it", vol_id, lnum);
 			err = add_to_list(si, pnum, ec, &si->corr);
 			if (err)
 				return err;
-			break;
+			return 0;
 
 		case UBI_COMPAT_RO:
 			ubi_msg("read-only compatible internal volume %d:%d"
···
 			err = add_to_list(si, pnum, ec, &si->alien);
 			if (err)
 				return err;
-			si->alien_peb_count += 1;
 			return 0;
 
 		case UBI_COMPAT_REJECT:
···
 }
 
 /**
+ * check_what_we_have - check what PEB were found by scanning.
+ * @ubi: UBI device description object
+ * @si: scanning information
+ *
+ * This is a helper function which takes a look what PEBs were found by
+ * scanning, and decides whether the flash is empty and should be formatted and
+ * whether there are too many corrupted PEBs and we should not attach this
+ * MTD device. Returns zero if we should proceed with attaching the MTD device,
+ * and %-EINVAL if we should not.
+ */
+static int check_what_we_have(struct ubi_device *ubi, struct ubi_scan_info *si)
+{
+	struct ubi_scan_leb *seb;
+	int max_corr;
+
+	max_corr = ubi->peb_count - si->bad_peb_count - si->alien_peb_count;
+	max_corr = max_corr / 20 ?: 8;
+
+	/*
+	 * Few corrupted PEBs are not a problem and may be just a result of
+	 * unclean reboots. However, many of them may indicate some problems
+	 * with the flash HW or driver.
+	 */
+	if (si->corr_peb_count >= 8) {
+		ubi_warn("%d PEBs are corrupted", si->corr_peb_count);
+		printk(KERN_WARNING "corrupted PEBs are:");
+		list_for_each_entry(seb, &si->corr, u.list)
+			printk(KERN_CONT " %d", seb->pnum);
+		printk(KERN_CONT "\n");
+
+		/*
+		 * If too many PEBs are corrupted, we refuse attaching,
+		 * otherwise, only print a warning.
+		 */
+		if (si->corr_peb_count >= max_corr) {
+			ubi_err("too many corrupted PEBs, refusing this device");
+			return -EINVAL;
+		}
+	}
+
+	if (si->free_peb_count + si->used_peb_count +
+	    si->alien_peb_count == 0) {
+		/* No UBI-formatted eraseblocks were found */
+		if (si->corr_peb_count == si->read_err_count &&
+		    si->corr_peb_count < 8) {
+			/* No or just few corrupted PEBs, and all of them had a
+			 * read error. We assume that those are bad PEBs, which
+			 * were just not marked as bad so far.
+			 *
+			 * This piece of code basically tries to distinguish
+			 * between the following 2 situations:
+			 *
+			 * 1. Flash is empty, but there are few bad PEBs, which
+			 *    are not marked as bad so far, and which were read
+			 *    with error. We want to go ahead and format this
+			 *    flash. While formating, the faulty PEBs will
+			 *    probably be marked as bad.
+			 *
+			 * 2. Flash probably contains non-UBI data and we do
+			 * not want to format it and destroy possibly needed
+			 * data (e.g., consider the case when the bootloader
+			 * MTD partition was accidentally fed to UBI).
+			 */
+			si->is_empty = 1;
+			ubi_msg("empty MTD device detected");
+			get_random_bytes(&ubi->image_seq, sizeof(ubi->image_seq));
+		} else {
+			ubi_err("MTD device possibly contains non-UBI data, "
+				"refusing it");
+			return -EINVAL;
+		}
+	}
+
+	if (si->corr_peb_count > 0)
+		ubi_msg("corrupted PEBs will be formatted");
+	return 0;
+}
+
+/**
  * ubi_scan - scan an MTD device.
  * @ubi: UBI device description object
  *
···
 	INIT_LIST_HEAD(&si->erase);
 	INIT_LIST_HEAD(&si->alien);
 	si->volumes = RB_ROOT;
-	si->is_empty = 1;
 
 	err = -ENOMEM;
 	ech = kzalloc(ubi->ec_hdr_alsize, GFP_KERNEL);
···
 	if (si->ec_count)
 		si->mean_ec = div_u64(si->ec_sum, si->ec_count);
 
-	if (si->is_empty)
-		ubi_msg("empty MTD device detected");
-
-	/*
-	 * Few corrupted PEBs are not a problem and may be just a result of
-	 * unclean reboots. However, many of them may indicate some problems
-	 * with the flash HW or driver. Print a warning in this case.
-	 */
-	if (si->corr_count >= 8 || si->corr_count >= ubi->peb_count / 4) {
-		ubi_warn("%d PEBs are corrupted", si->corr_count);
-		printk(KERN_WARNING "corrupted PEBs are:");
-		list_for_each_entry(seb, &si->corr, u.list)
-			printk(KERN_CONT " %d", seb->pnum);
-		printk(KERN_CONT "\n");
-	}
+	err = check_what_we_have(ubi, si);
+	if (err)
+		goto out_vidh;
 
 	/*
 	 * In case of unknown erase counter we use the mean erase counter

drivers/mtd/ubi/scan.h

···
  * @erase: list of physical eraseblocks which have to be erased
  * @alien: list of physical eraseblocks which should not be used by UBI (e.g.,
  *         those belonging to "preserve"-compatible internal volumes)
+ * @used_peb_count: count of used PEBs
+ * @corr_peb_count: count of PEBs in the @corr list
+ * @read_err_count: count of PEBs read with error (%UBI_IO_BAD_HDR_READ was
+ *                  returned)
+ * @free_peb_count: count of PEBs in the @free list
+ * @erase_peb_count: count of PEBs in the @erase list
+ * @alien_peb_count: count of PEBs in the @alien list
  * @bad_peb_count: count of bad physical eraseblocks
  * @vols_found: number of volumes found during scanning
  * @highest_vol_id: highest volume ID
- * @alien_peb_count: count of physical eraseblocks in the @alien list
  * @is_empty: flag indicating whether the MTD device is empty or not
  * @min_ec: lowest erase counter value
  * @max_ec: highest erase counter value
···
  * @mean_ec: mean erase counter value
  * @ec_sum: a temporary variable used when calculating @mean_ec
  * @ec_count: a temporary variable used when calculating @mean_ec
- * @corr_count: count of corrupted PEBs
  *
  * This data structure contains the result of scanning and may be used by other
  * UBI sub-systems to build final UBI data structures, further error-recovery
···
 	struct list_head free;
 	struct list_head erase;
 	struct list_head alien;
+	int used_peb_count;
+	int corr_peb_count;
+	int read_err_count;
+	int free_peb_count;
+	int erase_peb_count;
+	int alien_peb_count;
 	int bad_peb_count;
 	int vols_found;
 	int highest_vol_id;
-	int alien_peb_count;
 	int is_empty;
 	int min_ec;
 	int max_ec;
···
 	int mean_ec;
 	uint64_t ec_sum;
 	int ec_count;
-	int corr_count;
 };
 
 struct ubi_device;
···
  * ubi_scan_move_to_list - move a PEB from the volume tree to a list.
  *
  * @sv: volume scanning information
- * @seb: scanning eraseblock infprmation
+ * @seb: scanning eraseblock information
  * @list: the list to move to
  */
 static inline void ubi_scan_move_to_list(struct ubi_scan_volume *sv,

drivers/mtd/ubi/ubi.h

···
  *                   %0xFF bytes
  * 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_EC_HDR: the erase counter header is corrupted (bad magic or CRC)
- * UBI_IO_BAD_VID_HDR: the volume identifier header is corrupted (bad magic or
- *                     CRC)
+ * 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_EC_HDR,
-	UBI_IO_BAD_VID_HDR,
+	UBI_IO_BAD_HDR,
+	UBI_IO_BAD_HDR_READ,
 	UBI_IO_BITFLIPS
 };