badblocks: Add core badblock management code

			blk-iopoll.o blk-lib.o blk-mq.o blk-mq-tag.o \

			blk-mq-sysfs.o blk-mq-cpu.o blk-mq-cpumap.o ioctl.o \

			genhd.o scsi_ioctl.o partition-generic.o ioprio.o \

			partitions/

			badblocks.o partitions/

obj-$(CONFIG_BOUNCE)	+= bounce.o

obj-$(CONFIG_BLK_DEV_BSG)	+= bsg.o

/*

 * Bad block management

 *

 * - Heavily based on MD badblocks code from Neil Brown

 *

 * Copyright (c) 2015, Intel Corporation.

 *

 * This program is free software; you can redistribute it and/or modify it

 * under the terms and conditions of the GNU General Public License,

 * version 2, as published by the Free Software Foundation.

 *

 * This program is distributed in the hope it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for

 * more details.

 */

#include <linux/badblocks.h>

#include <linux/seqlock.h>

#include <linux/kernel.h>

#include <linux/module.h>

#include <linux/stddef.h>

#include <linux/types.h>

#include <linux/slab.h>

/**

 * badblocks_check() - check a given range for bad sectors

 * @bb:		the badblocks structure that holds all badblock information

 * @s:		sector (start) at which to check for badblocks

 * @sectors:	number of sectors to check for badblocks

 * @first_bad:	pointer to store location of the first badblock

 * @bad_sectors: pointer to store number of badblocks after @first_bad

 *

 * We can record which blocks on each device are 'bad' and so just

 * fail those blocks, or that stripe, rather than the whole device.

 * Entries in the bad-block table are 64bits wide.  This comprises:

 * Length of bad-range, in sectors: 0-511 for lengths 1-512

 * Start of bad-range, sector offset, 54 bits (allows 8 exbibytes)

 *  A 'shift' can be set so that larger blocks are tracked and

 *  consequently larger devices can be covered.

 * 'Acknowledged' flag - 1 bit. - the most significant bit.

 *

 * Locking of the bad-block table uses a seqlock so badblocks_check

 * might need to retry if it is very unlucky.

 * We will sometimes want to check for bad blocks in a bi_end_io function,

 * so we use the write_seqlock_irq variant.

 *

 * When looking for a bad block we specify a range and want to

 * know if any block in the range is bad.  So we binary-search

 * to the last range that starts at-or-before the given endpoint,

 * (or "before the sector after the target range")

 * then see if it ends after the given start.

 *

 * Return:

 *  0: there are no known bad blocks in the range

 *  1: there are known bad block which are all acknowledged

 * -1: there are bad blocks which have not yet been acknowledged in metadata.

 * plus the start/length of the first bad section we overlap.

 */

int badblocks_check(struct badblocks *bb, sector_t s, int sectors,

			sector_t *first_bad, int *bad_sectors)

{

	int hi;

	int lo;

	u64 *p = bb->page;

	int rv;

	sector_t target = s + sectors;

	unsigned seq;

	if (bb->shift > 0) {

		/* round the start down, and the end up */

		s >>= bb->shift;

		target += (1<<bb->shift) - 1;

		target >>= bb->shift;

		sectors = target - s;

	}

	/* 'target' is now the first block after the bad range */

retry:

	seq = read_seqbegin(&bb->lock);

	lo = 0;

	rv = 0;

	hi = bb->count;

	/* Binary search between lo and hi for 'target'

	 * i.e. for the last range that starts before 'target'

	 */

	/* INVARIANT: ranges before 'lo' and at-or-after 'hi'

	 * are known not to be the last range before target.

	 * VARIANT: hi-lo is the number of possible

	 * ranges, and decreases until it reaches 1

	 */

	while (hi - lo > 1) {

		int mid = (lo + hi) / 2;

		sector_t a = BB_OFFSET(p[mid]);

		if (a < target)

			/* This could still be the one, earlier ranges

			 * could not.

			 */

			lo = mid;

		else

			/* This and later ranges are definitely out. */

			hi = mid;

	}

	/* 'lo' might be the last that started before target, but 'hi' isn't */

	if (hi > lo) {

		/* need to check all range that end after 's' to see if

		 * any are unacknowledged.

		 */

		while (lo >= 0 &&

		       BB_OFFSET(p[lo]) + BB_LEN(p[lo]) > s) {

			if (BB_OFFSET(p[lo]) < target) {

				/* starts before the end, and finishes after

				 * the start, so they must overlap

				 */

				if (rv != -1 && BB_ACK(p[lo]))

					rv = 1;

				else

					rv = -1;

				*first_bad = BB_OFFSET(p[lo]);

				*bad_sectors = BB_LEN(p[lo]);

			}

			lo--;

		}

	}

	if (read_seqretry(&bb->lock, seq))

		goto retry;

	return rv;

}

EXPORT_SYMBOL_GPL(badblocks_check);

/**

 * badblocks_set() - Add a range of bad blocks to the table.

 * @bb:		the badblocks structure that holds all badblock information

 * @s:		first sector to mark as bad

 * @sectors:	number of sectors to mark as bad

 * @acknowledged: weather to mark the bad sectors as acknowledged

 *

 * This might extend the table, or might contract it if two adjacent ranges

 * can be merged. We binary-search to find the 'insertion' point, then

 * decide how best to handle it.

 *

 * Return:

 *  0: success

 *  1: failed to set badblocks (out of space)

 */

int badblocks_set(struct badblocks *bb, sector_t s, int sectors,

			int acknowledged)

{

	u64 *p;

	int lo, hi;

	int rv = 0;

	unsigned long flags;

	if (bb->shift < 0)

		/* badblocks are disabled */

		return 0;

	if (bb->shift) {

		/* round the start down, and the end up */

		sector_t next = s + sectors;

		s >>= bb->shift;

		next += (1<<bb->shift) - 1;

		next >>= bb->shift;

		sectors = next - s;

	}

	write_seqlock_irqsave(&bb->lock, flags);

	p = bb->page;

	lo = 0;

	hi = bb->count;

	/* Find the last range that starts at-or-before 's' */

	while (hi - lo > 1) {

		int mid = (lo + hi) / 2;

		sector_t a = BB_OFFSET(p[mid]);

		if (a <= s)

			lo = mid;

		else

			hi = mid;

	}

	if (hi > lo && BB_OFFSET(p[lo]) > s)

		hi = lo;

	if (hi > lo) {

		/* we found a range that might merge with the start

		 * of our new range

		 */

		sector_t a = BB_OFFSET(p[lo]);

		sector_t e = a + BB_LEN(p[lo]);

		int ack = BB_ACK(p[lo]);

		if (e >= s) {

			/* Yes, we can merge with a previous range */

			if (s == a && s + sectors >= e)

				/* new range covers old */

				ack = acknowledged;

			else

				ack = ack && acknowledged;

			if (e < s + sectors)

				e = s + sectors;

			if (e - a <= BB_MAX_LEN) {

				p[lo] = BB_MAKE(a, e-a, ack);

				s = e;

			} else {

				/* does not all fit in one range,

				 * make p[lo] maximal

				 */

				if (BB_LEN(p[lo]) != BB_MAX_LEN)

					p[lo] = BB_MAKE(a, BB_MAX_LEN, ack);

				s = a + BB_MAX_LEN;

			}

			sectors = e - s;

		}

	}

	if (sectors && hi < bb->count) {

		/* 'hi' points to the first range that starts after 's'.

		 * Maybe we can merge with the start of that range

		 */

		sector_t a = BB_OFFSET(p[hi]);

		sector_t e = a + BB_LEN(p[hi]);

		int ack = BB_ACK(p[hi]);

		if (a <= s + sectors) {

			/* merging is possible */

			if (e <= s + sectors) {

				/* full overlap */

				e = s + sectors;

				ack = acknowledged;

			} else

				ack = ack && acknowledged;

			a = s;

			if (e - a <= BB_MAX_LEN) {

				p[hi] = BB_MAKE(a, e-a, ack);

				s = e;

			} else {

				p[hi] = BB_MAKE(a, BB_MAX_LEN, ack);

				s = a + BB_MAX_LEN;

			}

			sectors = e - s;

			lo = hi;

			hi++;

		}

	}

	if (sectors == 0 && hi < bb->count) {

		/* we might be able to combine lo and hi */

		/* Note: 's' is at the end of 'lo' */

		sector_t a = BB_OFFSET(p[hi]);

		int lolen = BB_LEN(p[lo]);

		int hilen = BB_LEN(p[hi]);

		int newlen = lolen + hilen - (s - a);

		if (s >= a && newlen < BB_MAX_LEN) {

			/* yes, we can combine them */

			int ack = BB_ACK(p[lo]) && BB_ACK(p[hi]);

			p[lo] = BB_MAKE(BB_OFFSET(p[lo]), newlen, ack);

			memmove(p + hi, p + hi + 1,

				(bb->count - hi - 1) * 8);

			bb->count--;

		}

	}

	while (sectors) {

		/* didn't merge (it all).

		 * Need to add a range just before 'hi'

		 */

		if (bb->count >= MAX_BADBLOCKS) {

			/* No room for more */

			rv = 1;

			break;

		} else {

			int this_sectors = sectors;

			memmove(p + hi + 1, p + hi,

				(bb->count - hi) * 8);

			bb->count++;

			if (this_sectors > BB_MAX_LEN)

				this_sectors = BB_MAX_LEN;

			p[hi] = BB_MAKE(s, this_sectors, acknowledged);

			sectors -= this_sectors;

			s += this_sectors;

		}

	}

	bb->changed = 1;

	if (!acknowledged)

		bb->unacked_exist = 1;

	write_sequnlock_irqrestore(&bb->lock, flags);

	return rv;

}

EXPORT_SYMBOL_GPL(badblocks_set);

/**

 * badblocks_clear() - Remove a range of bad blocks to the table.

 * @bb:		the badblocks structure that holds all badblock information

 * @s:		first sector to mark as bad

 * @sectors:	number of sectors to mark as bad

 *

 * This may involve extending the table if we spilt a region,

 * but it must not fail.  So if the table becomes full, we just

 * drop the remove request.

 *

 * Return:

 *  0: success

 *  1: failed to clear badblocks

 */

int badblocks_clear(struct badblocks *bb, sector_t s, int sectors)

{

	u64 *p;

	int lo, hi;

	sector_t target = s + sectors;

	int rv = 0;

	if (bb->shift > 0) {

		/* When clearing we round the start up and the end down.

		 * This should not matter as the shift should align with

		 * the block size and no rounding should ever be needed.

		 * However it is better the think a block is bad when it

		 * isn't than to think a block is not bad when it is.

		 */

		s += (1<<bb->shift) - 1;

		s >>= bb->shift;

		target >>= bb->shift;

		sectors = target - s;

	}

	write_seqlock_irq(&bb->lock);

	p = bb->page;

	lo = 0;

	hi = bb->count;

	/* Find the last range that starts before 'target' */

	while (hi - lo > 1) {

		int mid = (lo + hi) / 2;

		sector_t a = BB_OFFSET(p[mid]);

		if (a < target)

			lo = mid;

		else

			hi = mid;

	}

	if (hi > lo) {

		/* p[lo] is the last range that could overlap the

		 * current range.  Earlier ranges could also overlap,

		 * but only this one can overlap the end of the range.

		 */

		if (BB_OFFSET(p[lo]) + BB_LEN(p[lo]) > target) {

			/* Partial overlap, leave the tail of this range */

			int ack = BB_ACK(p[lo]);

			sector_t a = BB_OFFSET(p[lo]);

			sector_t end = a + BB_LEN(p[lo]);

			if (a < s) {

				/* we need to split this range */

				if (bb->count >= MAX_BADBLOCKS) {

					rv = -ENOSPC;

					goto out;

				}

				memmove(p+lo+1, p+lo, (bb->count - lo) * 8);

				bb->count++;

				p[lo] = BB_MAKE(a, s-a, ack);

				lo++;

			}

			p[lo] = BB_MAKE(target, end - target, ack);

			/* there is no longer an overlap */

			hi = lo;

			lo--;

		}

		while (lo >= 0 &&

		       BB_OFFSET(p[lo]) + BB_LEN(p[lo]) > s) {

			/* This range does overlap */

			if (BB_OFFSET(p[lo]) < s) {

				/* Keep the early parts of this range. */

				int ack = BB_ACK(p[lo]);

				sector_t start = BB_OFFSET(p[lo]);

				p[lo] = BB_MAKE(start, s - start, ack);

				/* now low doesn't overlap, so.. */

				break;

			}

			lo--;

		}

		/* 'lo' is strictly before, 'hi' is strictly after,

		 * anything between needs to be discarded

		 */

		if (hi - lo > 1) {

			memmove(p+lo+1, p+hi, (bb->count - hi) * 8);

			bb->count -= (hi - lo - 1);

		}

	}

	bb->changed = 1;

out:

	write_sequnlock_irq(&bb->lock);

	return rv;

}

EXPORT_SYMBOL_GPL(badblocks_clear);

/**

 * ack_all_badblocks() - Acknowledge all bad blocks in a list.

 * @bb:		the badblocks structure that holds all badblock information

 *

 * This only succeeds if ->changed is clear.  It is used by

 * in-kernel metadata updates

 */

void ack_all_badblocks(struct badblocks *bb)

{

	if (bb->page == NULL || bb->changed)

		/* no point even trying */

		return;

	write_seqlock_irq(&bb->lock);

	if (bb->changed == 0 && bb->unacked_exist) {

		u64 *p = bb->page;

		int i;

		for (i = 0; i < bb->count ; i++) {

			if (!BB_ACK(p[i])) {

				sector_t start = BB_OFFSET(p[i]);

				int len = BB_LEN(p[i]);

				p[i] = BB_MAKE(start, len, 1);

			}

		}

		bb->unacked_exist = 0;

	}

	write_sequnlock_irq(&bb->lock);

}

EXPORT_SYMBOL_GPL(ack_all_badblocks);

/**

 * badblocks_show() - sysfs access to bad-blocks list

 * @bb:		the badblocks structure that holds all badblock information

 * @page:	buffer received from sysfs

 * @unack:	weather to show unacknowledged badblocks

 *

 * Return:

 *  Length of returned data

 */

ssize_t badblocks_show(struct badblocks *bb, char *page, int unack)

{

	size_t len;

	int i;

	u64 *p = bb->page;

	unsigned seq;

	if (bb->shift < 0)

		return 0;

retry:

	seq = read_seqbegin(&bb->lock);

	len = 0;

	i = 0;

	while (len < PAGE_SIZE && i < bb->count) {

		sector_t s = BB_OFFSET(p[i]);

		unsigned int length = BB_LEN(p[i]);

		int ack = BB_ACK(p[i]);

		i++;

		if (unack && ack)

			continue;

		len += snprintf(page+len, PAGE_SIZE-len, "%llu %u\n",

				(unsigned long long)s << bb->shift,

				length << bb->shift);

	}

	if (unack && len == 0)

		bb->unacked_exist = 0;

	if (read_seqretry(&bb->lock, seq))

		goto retry;

	return len;

}

EXPORT_SYMBOL_GPL(badblocks_show);

/**

 * badblocks_store() - sysfs access to bad-blocks list

 * @bb:		the badblocks structure that holds all badblock information

 * @page:	buffer received from sysfs

 * @len:	length of data received from sysfs

 * @unack:	weather to show unacknowledged badblocks

 *

 * Return:

 *  Length of the buffer processed or -ve error.

 */

ssize_t badblocks_store(struct badblocks *bb, const char *page, size_t len,

			int unack)

{

	unsigned long long sector;

	int length;

	char newline;

	switch (sscanf(page, "%llu %d%c", &sector, &length, &newline)) {

	case 3:

		if (newline != '\n')

			return -EINVAL;

	case 2:

		if (length <= 0)

			return -EINVAL;

		break;

	default:

		return -EINVAL;

	}

	if (badblocks_set(bb, sector, length, !unack))

		return -ENOSPC;

	else

		return len;

}

EXPORT_SYMBOL_GPL(badblocks_store);

/**

 * badblocks_init() - initialize the badblocks structure

 * @bb:		the badblocks structure that holds all badblock information

 * @enable:	weather to enable badblocks accounting

 *

 * Return:

 *  0: success

 *  -ve errno: on error

 */

int badblocks_init(struct badblocks *bb, int enable)

{

	bb->count = 0;

	if (enable)

		bb->shift = 0;

	else

		bb->shift = -1;

	bb->page = kzalloc(PAGE_SIZE, GFP_KERNEL);

	if (bb->page == (u64 *)0) {

		bb->shift = -1;

		return -ENOMEM;

	}

	seqlock_init(&bb->lock);

	return 0;

}

EXPORT_SYMBOL_GPL(badblocks_init);

/**

 * badblocks_free() - free the badblocks structure

 * @bb:		the badblocks structure that holds all badblock information

 */

void badblocks_free(struct badblocks *bb)

{

	kfree(bb->page);

	bb->page = NULL;

}

EXPORT_SYMBOL_GPL(badblocks_free);

#ifndef _LINUX_BADBLOCKS_H

#define _LINUX_BADBLOCKS_H

#include <linux/seqlock.h>

#include <linux/kernel.h>

#include <linux/stddef.h>

#include <linux/types.h>

#define BB_LEN_MASK	(0x00000000000001FFULL)

#define BB_OFFSET_MASK	(0x7FFFFFFFFFFFFE00ULL)

#define BB_ACK_MASK	(0x8000000000000000ULL)

#define BB_MAX_LEN	512

#define BB_OFFSET(x)	(((x) & BB_OFFSET_MASK) >> 9)

#define BB_LEN(x)	(((x) & BB_LEN_MASK) + 1)

#define BB_ACK(x)	(!!((x) & BB_ACK_MASK))

#define BB_MAKE(a, l, ack) (((a)<<9) | ((l)-1) | ((u64)(!!(ack)) << 63))

/* Bad block numbers are stored sorted in a single page.

 * 64bits is used for each block or extent.

 * 54 bits are sector number, 9 bits are extent size,

 * 1 bit is an 'acknowledged' flag.

 */

#define MAX_BADBLOCKS	(PAGE_SIZE/8)

struct badblocks {

	int count;		/* count of bad blocks */

	int unacked_exist;	/* there probably are unacknowledged

				 * bad blocks.  This is only cleared

				 * when a read discovers none

				 */

	int shift;		/* shift from sectors to block size

				 * a -ve shift means badblocks are

				 * disabled.*/

	u64 *page;		/* badblock list */

	int changed;

	seqlock_t lock;

	sector_t sector;

	sector_t size;		/* in sectors */

};

int badblocks_check(struct badblocks *bb, sector_t s, int sectors,

		   sector_t *first_bad, int *bad_sectors);

int badblocks_set(struct badblocks *bb, sector_t s, int sectors,

			int acknowledged);

int badblocks_clear(struct badblocks *bb, sector_t s, int sectors);

void ack_all_badblocks(struct badblocks *bb);

ssize_t badblocks_show(struct badblocks *bb, char *page, int unack);

ssize_t badblocks_store(struct badblocks *bb, const char *page, size_t len,

			int unack);

int badblocks_init(struct badblocks *bb, int enable);

void badblocks_free(struct badblocks *bb);

#endif