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607 lines
15 KiB
607 lines
15 KiB
// SPDX-License-Identifier: GPL-2.0-only |
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/* -*- mode: c; c-basic-offset: 8; -*- |
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* vim: noexpandtab sw=8 ts=8 sts=0: |
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* |
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* blockcheck.c |
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* |
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* Checksum and ECC codes for the OCFS2 userspace library. |
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* |
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* Copyright (C) 2006, 2008 Oracle. All rights reserved. |
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*/ |
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#include <linux/kernel.h> |
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#include <linux/types.h> |
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#include <linux/crc32.h> |
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#include <linux/buffer_head.h> |
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#include <linux/bitops.h> |
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#include <linux/debugfs.h> |
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#include <linux/module.h> |
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#include <linux/fs.h> |
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#include <asm/byteorder.h> |
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#include <cluster/masklog.h> |
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#include "ocfs2.h" |
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#include "blockcheck.h" |
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/* |
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* We use the following conventions: |
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* |
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* d = # data bits |
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* p = # parity bits |
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* c = # total code bits (d + p) |
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*/ |
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/* |
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* Calculate the bit offset in the hamming code buffer based on the bit's |
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* offset in the data buffer. Since the hamming code reserves all |
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* power-of-two bits for parity, the data bit number and the code bit |
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* number are offset by all the parity bits beforehand. |
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* |
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* Recall that bit numbers in hamming code are 1-based. This function |
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* takes the 0-based data bit from the caller. |
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* |
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* An example. Take bit 1 of the data buffer. 1 is a power of two (2^0), |
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* so it's a parity bit. 2 is a power of two (2^1), so it's a parity bit. |
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* 3 is not a power of two. So bit 1 of the data buffer ends up as bit 3 |
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* in the code buffer. |
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* |
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* The caller can pass in *p if it wants to keep track of the most recent |
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* number of parity bits added. This allows the function to start the |
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* calculation at the last place. |
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*/ |
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static unsigned int calc_code_bit(unsigned int i, unsigned int *p_cache) |
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{ |
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unsigned int b, p = 0; |
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/* |
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* Data bits are 0-based, but we're talking code bits, which |
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* are 1-based. |
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*/ |
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b = i + 1; |
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/* Use the cache if it is there */ |
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if (p_cache) |
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p = *p_cache; |
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b += p; |
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/* |
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* For every power of two below our bit number, bump our bit. |
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* |
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* We compare with (b + 1) because we have to compare with what b |
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* would be _if_ it were bumped up by the parity bit. Capice? |
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* |
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* p is set above. |
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*/ |
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for (; (1 << p) < (b + 1); p++) |
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b++; |
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if (p_cache) |
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*p_cache = p; |
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return b; |
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} |
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/* |
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* This is the low level encoder function. It can be called across |
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* multiple hunks just like the crc32 code. 'd' is the number of bits |
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* _in_this_hunk_. nr is the bit offset of this hunk. So, if you had |
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* two 512B buffers, you would do it like so: |
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* |
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* parity = ocfs2_hamming_encode(0, buf1, 512 * 8, 0); |
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* parity = ocfs2_hamming_encode(parity, buf2, 512 * 8, 512 * 8); |
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* |
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* If you just have one buffer, use ocfs2_hamming_encode_block(). |
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*/ |
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u32 ocfs2_hamming_encode(u32 parity, void *data, unsigned int d, unsigned int nr) |
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{ |
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unsigned int i, b, p = 0; |
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BUG_ON(!d); |
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/* |
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* b is the hamming code bit number. Hamming code specifies a |
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* 1-based array, but C uses 0-based. So 'i' is for C, and 'b' is |
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* for the algorithm. |
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* |
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* The i++ in the for loop is so that the start offset passed |
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* to ocfs2_find_next_bit_set() is one greater than the previously |
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* found bit. |
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*/ |
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for (i = 0; (i = ocfs2_find_next_bit(data, d, i)) < d; i++) |
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{ |
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/* |
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* i is the offset in this hunk, nr + i is the total bit |
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* offset. |
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*/ |
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b = calc_code_bit(nr + i, &p); |
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/* |
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* Data bits in the resultant code are checked by |
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* parity bits that are part of the bit number |
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* representation. Huh? |
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* |
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* <wikipedia href="https://en.wikipedia.org/wiki/Hamming_code"> |
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* In other words, the parity bit at position 2^k |
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* checks bits in positions having bit k set in |
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* their binary representation. Conversely, for |
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* instance, bit 13, i.e. 1101(2), is checked by |
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* bits 1000(2) = 8, 0100(2)=4 and 0001(2) = 1. |
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* </wikipedia> |
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* |
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* Note that 'k' is the _code_ bit number. 'b' in |
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* our loop. |
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*/ |
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parity ^= b; |
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} |
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/* While the data buffer was treated as little endian, the |
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* return value is in host endian. */ |
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return parity; |
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} |
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u32 ocfs2_hamming_encode_block(void *data, unsigned int blocksize) |
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{ |
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return ocfs2_hamming_encode(0, data, blocksize * 8, 0); |
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} |
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/* |
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* Like ocfs2_hamming_encode(), this can handle hunks. nr is the bit |
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* offset of the current hunk. If bit to be fixed is not part of the |
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* current hunk, this does nothing. |
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* |
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* If you only have one hunk, use ocfs2_hamming_fix_block(). |
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*/ |
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void ocfs2_hamming_fix(void *data, unsigned int d, unsigned int nr, |
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unsigned int fix) |
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{ |
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unsigned int i, b; |
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BUG_ON(!d); |
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/* |
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* If the bit to fix has an hweight of 1, it's a parity bit. One |
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* busted parity bit is its own error. Nothing to do here. |
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*/ |
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if (hweight32(fix) == 1) |
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return; |
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/* |
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* nr + d is the bit right past the data hunk we're looking at. |
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* If fix after that, nothing to do |
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*/ |
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if (fix >= calc_code_bit(nr + d, NULL)) |
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return; |
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/* |
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* nr is the offset in the data hunk we're starting at. Let's |
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* start b at the offset in the code buffer. See hamming_encode() |
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* for a more detailed description of 'b'. |
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*/ |
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b = calc_code_bit(nr, NULL); |
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/* If the fix is before this hunk, nothing to do */ |
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if (fix < b) |
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return; |
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for (i = 0; i < d; i++, b++) |
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{ |
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/* Skip past parity bits */ |
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while (hweight32(b) == 1) |
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b++; |
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/* |
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* i is the offset in this data hunk. |
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* nr + i is the offset in the total data buffer. |
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* b is the offset in the total code buffer. |
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* |
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* Thus, when b == fix, bit i in the current hunk needs |
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* fixing. |
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*/ |
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if (b == fix) |
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{ |
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if (ocfs2_test_bit(i, data)) |
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ocfs2_clear_bit(i, data); |
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else |
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ocfs2_set_bit(i, data); |
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break; |
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} |
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} |
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} |
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void ocfs2_hamming_fix_block(void *data, unsigned int blocksize, |
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unsigned int fix) |
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{ |
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ocfs2_hamming_fix(data, blocksize * 8, 0, fix); |
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} |
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/* |
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* Debugfs handling. |
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*/ |
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#ifdef CONFIG_DEBUG_FS |
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static int blockcheck_u64_get(void *data, u64 *val) |
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{ |
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*val = *(u64 *)data; |
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return 0; |
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} |
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DEFINE_SIMPLE_ATTRIBUTE(blockcheck_fops, blockcheck_u64_get, NULL, "%llu\n"); |
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static void ocfs2_blockcheck_debug_remove(struct ocfs2_blockcheck_stats *stats) |
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{ |
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if (stats) { |
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debugfs_remove_recursive(stats->b_debug_dir); |
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stats->b_debug_dir = NULL; |
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} |
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} |
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static void ocfs2_blockcheck_debug_install(struct ocfs2_blockcheck_stats *stats, |
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struct dentry *parent) |
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{ |
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struct dentry *dir; |
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dir = debugfs_create_dir("blockcheck", parent); |
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stats->b_debug_dir = dir; |
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debugfs_create_file("blocks_checked", S_IFREG | S_IRUSR, dir, |
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&stats->b_check_count, &blockcheck_fops); |
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debugfs_create_file("checksums_failed", S_IFREG | S_IRUSR, dir, |
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&stats->b_failure_count, &blockcheck_fops); |
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debugfs_create_file("ecc_recoveries", S_IFREG | S_IRUSR, dir, |
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&stats->b_recover_count, &blockcheck_fops); |
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} |
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#else |
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static inline void ocfs2_blockcheck_debug_install(struct ocfs2_blockcheck_stats *stats, |
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struct dentry *parent) |
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{ |
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} |
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static inline void ocfs2_blockcheck_debug_remove(struct ocfs2_blockcheck_stats *stats) |
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{ |
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} |
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#endif /* CONFIG_DEBUG_FS */ |
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/* Always-called wrappers for starting and stopping the debugfs files */ |
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void ocfs2_blockcheck_stats_debugfs_install(struct ocfs2_blockcheck_stats *stats, |
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struct dentry *parent) |
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{ |
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ocfs2_blockcheck_debug_install(stats, parent); |
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} |
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void ocfs2_blockcheck_stats_debugfs_remove(struct ocfs2_blockcheck_stats *stats) |
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{ |
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ocfs2_blockcheck_debug_remove(stats); |
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} |
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static void ocfs2_blockcheck_inc_check(struct ocfs2_blockcheck_stats *stats) |
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{ |
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u64 new_count; |
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if (!stats) |
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return; |
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spin_lock(&stats->b_lock); |
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stats->b_check_count++; |
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new_count = stats->b_check_count; |
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spin_unlock(&stats->b_lock); |
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if (!new_count) |
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mlog(ML_NOTICE, "Block check count has wrapped\n"); |
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} |
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static void ocfs2_blockcheck_inc_failure(struct ocfs2_blockcheck_stats *stats) |
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{ |
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u64 new_count; |
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if (!stats) |
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return; |
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spin_lock(&stats->b_lock); |
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stats->b_failure_count++; |
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new_count = stats->b_failure_count; |
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spin_unlock(&stats->b_lock); |
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if (!new_count) |
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mlog(ML_NOTICE, "Checksum failure count has wrapped\n"); |
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} |
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static void ocfs2_blockcheck_inc_recover(struct ocfs2_blockcheck_stats *stats) |
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{ |
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u64 new_count; |
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if (!stats) |
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return; |
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spin_lock(&stats->b_lock); |
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stats->b_recover_count++; |
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new_count = stats->b_recover_count; |
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spin_unlock(&stats->b_lock); |
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if (!new_count) |
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mlog(ML_NOTICE, "ECC recovery count has wrapped\n"); |
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} |
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/* |
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* These are the low-level APIs for using the ocfs2_block_check structure. |
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*/ |
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/* |
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* This function generates check information for a block. |
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* data is the block to be checked. bc is a pointer to the |
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* ocfs2_block_check structure describing the crc32 and the ecc. |
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* |
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* bc should be a pointer inside data, as the function will |
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* take care of zeroing it before calculating the check information. If |
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* bc does not point inside data, the caller must make sure any inline |
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* ocfs2_block_check structures are zeroed. |
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* |
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* The data buffer must be in on-disk endian (little endian for ocfs2). |
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* bc will be filled with little-endian values and will be ready to go to |
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* disk. |
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*/ |
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void ocfs2_block_check_compute(void *data, size_t blocksize, |
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struct ocfs2_block_check *bc) |
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{ |
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u32 crc; |
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u32 ecc; |
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memset(bc, 0, sizeof(struct ocfs2_block_check)); |
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crc = crc32_le(~0, data, blocksize); |
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ecc = ocfs2_hamming_encode_block(data, blocksize); |
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/* |
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* No ecc'd ocfs2 structure is larger than 4K, so ecc will be no |
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* larger than 16 bits. |
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*/ |
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BUG_ON(ecc > USHRT_MAX); |
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bc->bc_crc32e = cpu_to_le32(crc); |
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bc->bc_ecc = cpu_to_le16((u16)ecc); |
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} |
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/* |
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* This function validates existing check information. Like _compute, |
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* the function will take care of zeroing bc before calculating check codes. |
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* If bc is not a pointer inside data, the caller must have zeroed any |
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* inline ocfs2_block_check structures. |
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* |
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* Again, the data passed in should be the on-disk endian. |
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*/ |
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int ocfs2_block_check_validate(void *data, size_t blocksize, |
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struct ocfs2_block_check *bc, |
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struct ocfs2_blockcheck_stats *stats) |
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{ |
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int rc = 0; |
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u32 bc_crc32e; |
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u16 bc_ecc; |
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u32 crc, ecc; |
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ocfs2_blockcheck_inc_check(stats); |
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bc_crc32e = le32_to_cpu(bc->bc_crc32e); |
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bc_ecc = le16_to_cpu(bc->bc_ecc); |
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memset(bc, 0, sizeof(struct ocfs2_block_check)); |
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/* Fast path - if the crc32 validates, we're good to go */ |
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crc = crc32_le(~0, data, blocksize); |
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if (crc == bc_crc32e) |
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goto out; |
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ocfs2_blockcheck_inc_failure(stats); |
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mlog(ML_ERROR, |
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"CRC32 failed: stored: 0x%x, computed 0x%x. Applying ECC.\n", |
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(unsigned int)bc_crc32e, (unsigned int)crc); |
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/* Ok, try ECC fixups */ |
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ecc = ocfs2_hamming_encode_block(data, blocksize); |
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ocfs2_hamming_fix_block(data, blocksize, ecc ^ bc_ecc); |
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/* And check the crc32 again */ |
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crc = crc32_le(~0, data, blocksize); |
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if (crc == bc_crc32e) { |
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ocfs2_blockcheck_inc_recover(stats); |
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goto out; |
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} |
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mlog(ML_ERROR, "Fixed CRC32 failed: stored: 0x%x, computed 0x%x\n", |
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(unsigned int)bc_crc32e, (unsigned int)crc); |
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rc = -EIO; |
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out: |
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bc->bc_crc32e = cpu_to_le32(bc_crc32e); |
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bc->bc_ecc = cpu_to_le16(bc_ecc); |
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return rc; |
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} |
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/* |
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* This function generates check information for a list of buffer_heads. |
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* bhs is the blocks to be checked. bc is a pointer to the |
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* ocfs2_block_check structure describing the crc32 and the ecc. |
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* |
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* bc should be a pointer inside data, as the function will |
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* take care of zeroing it before calculating the check information. If |
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* bc does not point inside data, the caller must make sure any inline |
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* ocfs2_block_check structures are zeroed. |
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* |
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* The data buffer must be in on-disk endian (little endian for ocfs2). |
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* bc will be filled with little-endian values and will be ready to go to |
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* disk. |
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*/ |
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void ocfs2_block_check_compute_bhs(struct buffer_head **bhs, int nr, |
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struct ocfs2_block_check *bc) |
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{ |
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int i; |
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u32 crc, ecc; |
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BUG_ON(nr < 0); |
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if (!nr) |
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return; |
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memset(bc, 0, sizeof(struct ocfs2_block_check)); |
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for (i = 0, crc = ~0, ecc = 0; i < nr; i++) { |
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crc = crc32_le(crc, bhs[i]->b_data, bhs[i]->b_size); |
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/* |
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* The number of bits in a buffer is obviously b_size*8. |
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* The offset of this buffer is b_size*i, so the bit offset |
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* of this buffer is b_size*8*i. |
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*/ |
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ecc = (u16)ocfs2_hamming_encode(ecc, bhs[i]->b_data, |
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bhs[i]->b_size * 8, |
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bhs[i]->b_size * 8 * i); |
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} |
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|
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/* |
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* No ecc'd ocfs2 structure is larger than 4K, so ecc will be no |
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* larger than 16 bits. |
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*/ |
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BUG_ON(ecc > USHRT_MAX); |
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bc->bc_crc32e = cpu_to_le32(crc); |
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bc->bc_ecc = cpu_to_le16((u16)ecc); |
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} |
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|
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/* |
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* This function validates existing check information on a list of |
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* buffer_heads. Like _compute_bhs, the function will take care of |
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* zeroing bc before calculating check codes. If bc is not a pointer |
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* inside data, the caller must have zeroed any inline |
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* ocfs2_block_check structures. |
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* |
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* Again, the data passed in should be the on-disk endian. |
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*/ |
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int ocfs2_block_check_validate_bhs(struct buffer_head **bhs, int nr, |
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struct ocfs2_block_check *bc, |
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struct ocfs2_blockcheck_stats *stats) |
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{ |
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int i, rc = 0; |
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u32 bc_crc32e; |
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u16 bc_ecc; |
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u32 crc, ecc, fix; |
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BUG_ON(nr < 0); |
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|
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if (!nr) |
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return 0; |
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ocfs2_blockcheck_inc_check(stats); |
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bc_crc32e = le32_to_cpu(bc->bc_crc32e); |
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bc_ecc = le16_to_cpu(bc->bc_ecc); |
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memset(bc, 0, sizeof(struct ocfs2_block_check)); |
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|
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/* Fast path - if the crc32 validates, we're good to go */ |
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for (i = 0, crc = ~0; i < nr; i++) |
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crc = crc32_le(crc, bhs[i]->b_data, bhs[i]->b_size); |
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if (crc == bc_crc32e) |
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goto out; |
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ocfs2_blockcheck_inc_failure(stats); |
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mlog(ML_ERROR, |
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"CRC32 failed: stored: %u, computed %u. Applying ECC.\n", |
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(unsigned int)bc_crc32e, (unsigned int)crc); |
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|
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/* Ok, try ECC fixups */ |
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for (i = 0, ecc = 0; i < nr; i++) { |
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/* |
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* The number of bits in a buffer is obviously b_size*8. |
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* The offset of this buffer is b_size*i, so the bit offset |
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* of this buffer is b_size*8*i. |
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*/ |
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ecc = (u16)ocfs2_hamming_encode(ecc, bhs[i]->b_data, |
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bhs[i]->b_size * 8, |
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bhs[i]->b_size * 8 * i); |
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} |
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fix = ecc ^ bc_ecc; |
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for (i = 0; i < nr; i++) { |
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/* |
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* Try the fix against each buffer. It will only affect |
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* one of them. |
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*/ |
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ocfs2_hamming_fix(bhs[i]->b_data, bhs[i]->b_size * 8, |
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bhs[i]->b_size * 8 * i, fix); |
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} |
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|
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/* And check the crc32 again */ |
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for (i = 0, crc = ~0; i < nr; i++) |
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crc = crc32_le(crc, bhs[i]->b_data, bhs[i]->b_size); |
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if (crc == bc_crc32e) { |
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ocfs2_blockcheck_inc_recover(stats); |
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goto out; |
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} |
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|
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mlog(ML_ERROR, "Fixed CRC32 failed: stored: %u, computed %u\n", |
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(unsigned int)bc_crc32e, (unsigned int)crc); |
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|
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rc = -EIO; |
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out: |
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bc->bc_crc32e = cpu_to_le32(bc_crc32e); |
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bc->bc_ecc = cpu_to_le16(bc_ecc); |
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|
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return rc; |
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} |
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|
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/* |
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* These are the main API. They check the superblock flag before |
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* calling the underlying operations. |
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* |
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* They expect the buffer(s) to be in disk format. |
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*/ |
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void ocfs2_compute_meta_ecc(struct super_block *sb, void *data, |
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struct ocfs2_block_check *bc) |
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{ |
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if (ocfs2_meta_ecc(OCFS2_SB(sb))) |
|
ocfs2_block_check_compute(data, sb->s_blocksize, bc); |
|
} |
|
|
|
int ocfs2_validate_meta_ecc(struct super_block *sb, void *data, |
|
struct ocfs2_block_check *bc) |
|
{ |
|
int rc = 0; |
|
struct ocfs2_super *osb = OCFS2_SB(sb); |
|
|
|
if (ocfs2_meta_ecc(osb)) |
|
rc = ocfs2_block_check_validate(data, sb->s_blocksize, bc, |
|
&osb->osb_ecc_stats); |
|
|
|
return rc; |
|
} |
|
|
|
void ocfs2_compute_meta_ecc_bhs(struct super_block *sb, |
|
struct buffer_head **bhs, int nr, |
|
struct ocfs2_block_check *bc) |
|
{ |
|
if (ocfs2_meta_ecc(OCFS2_SB(sb))) |
|
ocfs2_block_check_compute_bhs(bhs, nr, bc); |
|
} |
|
|
|
int ocfs2_validate_meta_ecc_bhs(struct super_block *sb, |
|
struct buffer_head **bhs, int nr, |
|
struct ocfs2_block_check *bc) |
|
{ |
|
int rc = 0; |
|
struct ocfs2_super *osb = OCFS2_SB(sb); |
|
|
|
if (ocfs2_meta_ecc(osb)) |
|
rc = ocfs2_block_check_validate_bhs(bhs, nr, bc, |
|
&osb->osb_ecc_stats); |
|
|
|
return rc; |
|
} |
|
|
|
|