586 lines
14 KiB
C
586 lines
14 KiB
C
/*
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* Bad block management
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*
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* - Heavily based on MD badblocks code from Neil Brown
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*
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* Copyright (c) 2015, Intel Corporation.
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms and conditions of the GNU General Public License,
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* version 2, as published by the Free Software Foundation.
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*
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* This program is distributed in the hope it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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* more details.
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*/
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#include <linux/badblocks.h>
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#include <linux/seqlock.h>
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#include <linux/device.h>
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/stddef.h>
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#include <linux/types.h>
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#include <linux/slab.h>
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/**
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* badblocks_check() - check a given range for bad sectors
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* @bb: the badblocks structure that holds all badblock information
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* @s: sector (start) at which to check for badblocks
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* @sectors: number of sectors to check for badblocks
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* @first_bad: pointer to store location of the first badblock
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* @bad_sectors: pointer to store number of badblocks after @first_bad
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*
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* We can record which blocks on each device are 'bad' and so just
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* fail those blocks, or that stripe, rather than the whole device.
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* Entries in the bad-block table are 64bits wide. This comprises:
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* Length of bad-range, in sectors: 0-511 for lengths 1-512
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* Start of bad-range, sector offset, 54 bits (allows 8 exbibytes)
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* A 'shift' can be set so that larger blocks are tracked and
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* consequently larger devices can be covered.
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* 'Acknowledged' flag - 1 bit. - the most significant bit.
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*
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* Locking of the bad-block table uses a seqlock so badblocks_check
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* might need to retry if it is very unlucky.
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* We will sometimes want to check for bad blocks in a bi_end_io function,
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* so we use the write_seqlock_irq variant.
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*
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* When looking for a bad block we specify a range and want to
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* know if any block in the range is bad. So we binary-search
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* to the last range that starts at-or-before the given endpoint,
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* (or "before the sector after the target range")
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* then see if it ends after the given start.
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*
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* Return:
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* 0: there are no known bad blocks in the range
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* 1: there are known bad block which are all acknowledged
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* -1: there are bad blocks which have not yet been acknowledged in metadata.
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* plus the start/length of the first bad section we overlap.
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*/
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int badblocks_check(struct badblocks *bb, sector_t s, int sectors,
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sector_t *first_bad, int *bad_sectors)
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{
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int hi;
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int lo;
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u64 *p = bb->page;
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int rv;
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sector_t target = s + sectors;
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unsigned seq;
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if (bb->shift > 0) {
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/* round the start down, and the end up */
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s >>= bb->shift;
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target += (1<<bb->shift) - 1;
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target >>= bb->shift;
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sectors = target - s;
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}
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/* 'target' is now the first block after the bad range */
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retry:
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seq = read_seqbegin(&bb->lock);
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lo = 0;
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rv = 0;
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hi = bb->count;
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/* Binary search between lo and hi for 'target'
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* i.e. for the last range that starts before 'target'
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*/
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/* INVARIANT: ranges before 'lo' and at-or-after 'hi'
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* are known not to be the last range before target.
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* VARIANT: hi-lo is the number of possible
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* ranges, and decreases until it reaches 1
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*/
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while (hi - lo > 1) {
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int mid = (lo + hi) / 2;
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sector_t a = BB_OFFSET(p[mid]);
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if (a < target)
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/* This could still be the one, earlier ranges
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* could not.
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*/
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lo = mid;
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else
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/* This and later ranges are definitely out. */
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hi = mid;
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}
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/* 'lo' might be the last that started before target, but 'hi' isn't */
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if (hi > lo) {
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/* need to check all range that end after 's' to see if
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* any are unacknowledged.
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*/
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while (lo >= 0 &&
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BB_OFFSET(p[lo]) + BB_LEN(p[lo]) > s) {
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if (BB_OFFSET(p[lo]) < target) {
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/* starts before the end, and finishes after
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* the start, so they must overlap
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*/
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if (rv != -1 && BB_ACK(p[lo]))
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rv = 1;
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else
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rv = -1;
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*first_bad = BB_OFFSET(p[lo]);
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*bad_sectors = BB_LEN(p[lo]);
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}
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lo--;
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}
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}
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if (read_seqretry(&bb->lock, seq))
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goto retry;
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return rv;
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}
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EXPORT_SYMBOL_GPL(badblocks_check);
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/**
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* badblocks_set() - Add a range of bad blocks to the table.
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* @bb: the badblocks structure that holds all badblock information
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* @s: first sector to mark as bad
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* @sectors: number of sectors to mark as bad
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* @acknowledged: weather to mark the bad sectors as acknowledged
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*
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* This might extend the table, or might contract it if two adjacent ranges
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* can be merged. We binary-search to find the 'insertion' point, then
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* decide how best to handle it.
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*
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* Return:
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* 0: success
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* 1: failed to set badblocks (out of space)
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*/
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int badblocks_set(struct badblocks *bb, sector_t s, int sectors,
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int acknowledged)
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{
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u64 *p;
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int lo, hi;
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int rv = 0;
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unsigned long flags;
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if (bb->shift < 0)
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/* badblocks are disabled */
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return 0;
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if (bb->shift) {
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/* round the start down, and the end up */
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sector_t next = s + sectors;
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s >>= bb->shift;
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next += (1<<bb->shift) - 1;
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next >>= bb->shift;
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sectors = next - s;
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}
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write_seqlock_irqsave(&bb->lock, flags);
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p = bb->page;
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lo = 0;
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hi = bb->count;
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/* Find the last range that starts at-or-before 's' */
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while (hi - lo > 1) {
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int mid = (lo + hi) / 2;
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sector_t a = BB_OFFSET(p[mid]);
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if (a <= s)
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lo = mid;
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else
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hi = mid;
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}
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if (hi > lo && BB_OFFSET(p[lo]) > s)
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hi = lo;
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if (hi > lo) {
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/* we found a range that might merge with the start
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* of our new range
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*/
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sector_t a = BB_OFFSET(p[lo]);
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sector_t e = a + BB_LEN(p[lo]);
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int ack = BB_ACK(p[lo]);
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if (e >= s) {
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/* Yes, we can merge with a previous range */
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if (s == a && s + sectors >= e)
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/* new range covers old */
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ack = acknowledged;
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else
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ack = ack && acknowledged;
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if (e < s + sectors)
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e = s + sectors;
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if (e - a <= BB_MAX_LEN) {
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p[lo] = BB_MAKE(a, e-a, ack);
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s = e;
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} else {
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/* does not all fit in one range,
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* make p[lo] maximal
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*/
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if (BB_LEN(p[lo]) != BB_MAX_LEN)
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p[lo] = BB_MAKE(a, BB_MAX_LEN, ack);
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s = a + BB_MAX_LEN;
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}
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sectors = e - s;
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}
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}
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if (sectors && hi < bb->count) {
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/* 'hi' points to the first range that starts after 's'.
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* Maybe we can merge with the start of that range
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*/
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sector_t a = BB_OFFSET(p[hi]);
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sector_t e = a + BB_LEN(p[hi]);
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int ack = BB_ACK(p[hi]);
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if (a <= s + sectors) {
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/* merging is possible */
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if (e <= s + sectors) {
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/* full overlap */
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e = s + sectors;
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ack = acknowledged;
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} else
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ack = ack && acknowledged;
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a = s;
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if (e - a <= BB_MAX_LEN) {
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p[hi] = BB_MAKE(a, e-a, ack);
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s = e;
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} else {
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p[hi] = BB_MAKE(a, BB_MAX_LEN, ack);
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s = a + BB_MAX_LEN;
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}
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sectors = e - s;
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lo = hi;
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hi++;
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}
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}
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if (sectors == 0 && hi < bb->count) {
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/* we might be able to combine lo and hi */
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/* Note: 's' is at the end of 'lo' */
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sector_t a = BB_OFFSET(p[hi]);
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int lolen = BB_LEN(p[lo]);
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int hilen = BB_LEN(p[hi]);
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int newlen = lolen + hilen - (s - a);
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if (s >= a && newlen < BB_MAX_LEN) {
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/* yes, we can combine them */
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int ack = BB_ACK(p[lo]) && BB_ACK(p[hi]);
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p[lo] = BB_MAKE(BB_OFFSET(p[lo]), newlen, ack);
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memmove(p + hi, p + hi + 1,
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(bb->count - hi - 1) * 8);
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bb->count--;
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}
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}
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while (sectors) {
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/* didn't merge (it all).
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* Need to add a range just before 'hi'
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*/
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if (bb->count >= MAX_BADBLOCKS) {
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/* No room for more */
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rv = 1;
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break;
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} else {
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int this_sectors = sectors;
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memmove(p + hi + 1, p + hi,
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(bb->count - hi) * 8);
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bb->count++;
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if (this_sectors > BB_MAX_LEN)
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this_sectors = BB_MAX_LEN;
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p[hi] = BB_MAKE(s, this_sectors, acknowledged);
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sectors -= this_sectors;
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s += this_sectors;
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}
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}
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bb->changed = 1;
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if (!acknowledged)
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bb->unacked_exist = 1;
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write_sequnlock_irqrestore(&bb->lock, flags);
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return rv;
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}
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EXPORT_SYMBOL_GPL(badblocks_set);
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/**
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* badblocks_clear() - Remove a range of bad blocks to the table.
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* @bb: the badblocks structure that holds all badblock information
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* @s: first sector to mark as bad
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* @sectors: number of sectors to mark as bad
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*
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* This may involve extending the table if we spilt a region,
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* but it must not fail. So if the table becomes full, we just
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* drop the remove request.
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*
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* Return:
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* 0: success
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* 1: failed to clear badblocks
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*/
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int badblocks_clear(struct badblocks *bb, sector_t s, int sectors)
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{
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u64 *p;
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int lo, hi;
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sector_t target = s + sectors;
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int rv = 0;
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if (bb->shift > 0) {
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/* When clearing we round the start up and the end down.
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* This should not matter as the shift should align with
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* the block size and no rounding should ever be needed.
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* However it is better the think a block is bad when it
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* isn't than to think a block is not bad when it is.
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*/
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s += (1<<bb->shift) - 1;
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s >>= bb->shift;
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target >>= bb->shift;
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sectors = target - s;
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}
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write_seqlock_irq(&bb->lock);
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p = bb->page;
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lo = 0;
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hi = bb->count;
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/* Find the last range that starts before 'target' */
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while (hi - lo > 1) {
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int mid = (lo + hi) / 2;
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sector_t a = BB_OFFSET(p[mid]);
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if (a < target)
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lo = mid;
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else
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hi = mid;
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}
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if (hi > lo) {
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/* p[lo] is the last range that could overlap the
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* current range. Earlier ranges could also overlap,
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* but only this one can overlap the end of the range.
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*/
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if (BB_OFFSET(p[lo]) + BB_LEN(p[lo]) > target) {
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/* Partial overlap, leave the tail of this range */
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int ack = BB_ACK(p[lo]);
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sector_t a = BB_OFFSET(p[lo]);
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sector_t end = a + BB_LEN(p[lo]);
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if (a < s) {
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/* we need to split this range */
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if (bb->count >= MAX_BADBLOCKS) {
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rv = -ENOSPC;
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goto out;
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}
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memmove(p+lo+1, p+lo, (bb->count - lo) * 8);
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bb->count++;
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p[lo] = BB_MAKE(a, s-a, ack);
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lo++;
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}
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p[lo] = BB_MAKE(target, end - target, ack);
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/* there is no longer an overlap */
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hi = lo;
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lo--;
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}
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while (lo >= 0 &&
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BB_OFFSET(p[lo]) + BB_LEN(p[lo]) > s) {
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/* This range does overlap */
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if (BB_OFFSET(p[lo]) < s) {
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/* Keep the early parts of this range. */
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int ack = BB_ACK(p[lo]);
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sector_t start = BB_OFFSET(p[lo]);
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p[lo] = BB_MAKE(start, s - start, ack);
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/* now low doesn't overlap, so.. */
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break;
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}
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lo--;
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}
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/* 'lo' is strictly before, 'hi' is strictly after,
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* anything between needs to be discarded
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*/
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if (hi - lo > 1) {
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memmove(p+lo+1, p+hi, (bb->count - hi) * 8);
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bb->count -= (hi - lo - 1);
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}
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}
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bb->changed = 1;
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out:
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write_sequnlock_irq(&bb->lock);
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return rv;
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}
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EXPORT_SYMBOL_GPL(badblocks_clear);
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/**
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* ack_all_badblocks() - Acknowledge all bad blocks in a list.
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* @bb: the badblocks structure that holds all badblock information
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*
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* This only succeeds if ->changed is clear. It is used by
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* in-kernel metadata updates
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*/
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void ack_all_badblocks(struct badblocks *bb)
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{
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if (bb->page == NULL || bb->changed)
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/* no point even trying */
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return;
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write_seqlock_irq(&bb->lock);
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if (bb->changed == 0 && bb->unacked_exist) {
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u64 *p = bb->page;
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int i;
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for (i = 0; i < bb->count ; i++) {
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if (!BB_ACK(p[i])) {
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sector_t start = BB_OFFSET(p[i]);
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int len = BB_LEN(p[i]);
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p[i] = BB_MAKE(start, len, 1);
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}
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}
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bb->unacked_exist = 0;
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}
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write_sequnlock_irq(&bb->lock);
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}
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EXPORT_SYMBOL_GPL(ack_all_badblocks);
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/**
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* badblocks_show() - sysfs access to bad-blocks list
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* @bb: the badblocks structure that holds all badblock information
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* @page: buffer received from sysfs
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* @unack: weather to show unacknowledged badblocks
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*
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* Return:
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* Length of returned data
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*/
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ssize_t badblocks_show(struct badblocks *bb, char *page, int unack)
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{
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size_t len;
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int i;
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u64 *p = bb->page;
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unsigned seq;
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if (bb->shift < 0)
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return 0;
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retry:
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seq = read_seqbegin(&bb->lock);
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len = 0;
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i = 0;
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while (len < PAGE_SIZE && i < bb->count) {
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sector_t s = BB_OFFSET(p[i]);
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unsigned int length = BB_LEN(p[i]);
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int ack = BB_ACK(p[i]);
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i++;
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if (unack && ack)
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continue;
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len += snprintf(page+len, PAGE_SIZE-len, "%llu %u\n",
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(unsigned long long)s << bb->shift,
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length << bb->shift);
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}
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if (unack && len == 0)
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bb->unacked_exist = 0;
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if (read_seqretry(&bb->lock, seq))
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goto retry;
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return len;
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}
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EXPORT_SYMBOL_GPL(badblocks_show);
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/**
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* badblocks_store() - sysfs access to bad-blocks list
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* @bb: the badblocks structure that holds all badblock information
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* @page: buffer received from sysfs
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* @len: length of data received from sysfs
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* @unack: weather to show unacknowledged badblocks
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*
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* Return:
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* Length of the buffer processed or -ve error.
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*/
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ssize_t badblocks_store(struct badblocks *bb, const char *page, size_t len,
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int unack)
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{
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unsigned long long sector;
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int length;
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char newline;
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switch (sscanf(page, "%llu %d%c", §or, &length, &newline)) {
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case 3:
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if (newline != '\n')
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return -EINVAL;
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case 2:
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if (length <= 0)
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return -EINVAL;
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break;
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default:
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return -EINVAL;
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}
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if (badblocks_set(bb, sector, length, !unack))
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return -ENOSPC;
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else
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return len;
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}
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EXPORT_SYMBOL_GPL(badblocks_store);
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static int __badblocks_init(struct device *dev, struct badblocks *bb,
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int enable)
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{
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bb->dev = dev;
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bb->count = 0;
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if (enable)
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bb->shift = 0;
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else
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bb->shift = -1;
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if (dev)
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bb->page = devm_kzalloc(dev, PAGE_SIZE, GFP_KERNEL);
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else
|
|
bb->page = kzalloc(PAGE_SIZE, GFP_KERNEL);
|
|
if (!bb->page) {
|
|
bb->shift = -1;
|
|
return -ENOMEM;
|
|
}
|
|
seqlock_init(&bb->lock);
|
|
|
|
return 0;
|
|
}
|
|
|
|
/**
|
|
* 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)
|
|
{
|
|
return __badblocks_init(NULL, bb, enable);
|
|
}
|
|
EXPORT_SYMBOL_GPL(badblocks_init);
|
|
|
|
int devm_init_badblocks(struct device *dev, struct badblocks *bb)
|
|
{
|
|
if (!bb)
|
|
return -EINVAL;
|
|
return __badblocks_init(dev, bb, 1);
|
|
}
|
|
EXPORT_SYMBOL_GPL(devm_init_badblocks);
|
|
|
|
/**
|
|
* badblocks_exit() - free the badblocks structure
|
|
* @bb: the badblocks structure that holds all badblock information
|
|
*/
|
|
void badblocks_exit(struct badblocks *bb)
|
|
{
|
|
if (!bb)
|
|
return;
|
|
if (bb->dev)
|
|
devm_kfree(bb->dev, bb->page);
|
|
else
|
|
kfree(bb->page);
|
|
bb->page = NULL;
|
|
}
|
|
EXPORT_SYMBOL_GPL(badblocks_exit);
|