From aa6f5ffbdba45aa8e19e5048648fc6c7b25376d3 Mon Sep 17 00:00:00 2001 From: merge Date: Thu, 22 Jan 2009 13:55:32 +0000 Subject: MERGE-via-pending-tracking-hist-MERGE-via-stable-tracking-MERGE-via-mokopatches-tracking-fix-stray-endmenu-patch-1232632040-1232632141 pending-tracking-hist top was MERGE-via-stable-tracking-MERGE-via-mokopatches-tracking-fix-stray-endmenu-patch-1232632040-1232632141 / fdf777a63bcb59e0dfd78bfe2c6242e01f6d4eb9 ... parent commitmessage: From: merge MERGE-via-stable-tracking-hist-MERGE-via-mokopatches-tracking-fix-stray-endmenu-patch-1232632040 stable-tracking-hist top was MERGE-via-mokopatches-tracking-fix-stray-endmenu-patch-1232632040 / 90463bfd2d5a3c8b52f6e6d71024a00e052b0ced ... parent commitmessage: From: merge MERGE-via-mokopatches-tracking-hist-fix-stray-endmenu-patch mokopatches-tracking-hist top was fix-stray-endmenu-patch / 3630e0be570de8057e7f8d2fe501ed353cdf34e6 ... parent commitmessage: From: Andy Green fix-stray-endmenu.patch Signed-off-by: Andy Green --- fs/ocfs2/blockcheck.c | 477 ++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 477 insertions(+) create mode 100644 fs/ocfs2/blockcheck.c (limited to 'fs/ocfs2/blockcheck.c') diff --git a/fs/ocfs2/blockcheck.c b/fs/ocfs2/blockcheck.c new file mode 100644 index 00000000000..2a947c44e59 --- /dev/null +++ b/fs/ocfs2/blockcheck.c @@ -0,0 +1,477 @@ +/* -*- mode: c; c-basic-offset: 8; -*- + * vim: noexpandtab sw=8 ts=8 sts=0: + * + * blockcheck.c + * + * Checksum and ECC codes for the OCFS2 userspace library. + * + * Copyright (C) 2006, 2008 Oracle. All rights reserved. + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public + * License, version 2, as published by the Free Software Foundation. + * + * This program is distributed in the hope that 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 +#include +#include +#include +#include +#include + +#include + +#include "ocfs2.h" + +#include "blockcheck.h" + + +/* + * We use the following conventions: + * + * d = # data bits + * p = # parity bits + * c = # total code bits (d + p) + */ + + +/* + * Calculate the bit offset in the hamming code buffer based on the bit's + * offset in the data buffer. Since the hamming code reserves all + * power-of-two bits for parity, the data bit number and the code bit + * number are offest by all the parity bits beforehand. + * + * Recall that bit numbers in hamming code are 1-based. This function + * takes the 0-based data bit from the caller. + * + * An example. Take bit 1 of the data buffer. 1 is a power of two (2^0), + * so it's a parity bit. 2 is a power of two (2^1), so it's a parity bit. + * 3 is not a power of two. So bit 1 of the data buffer ends up as bit 3 + * in the code buffer. + * + * The caller can pass in *p if it wants to keep track of the most recent + * number of parity bits added. This allows the function to start the + * calculation at the last place. + */ +static unsigned int calc_code_bit(unsigned int i, unsigned int *p_cache) +{ + unsigned int b, p = 0; + + /* + * Data bits are 0-based, but we're talking code bits, which + * are 1-based. + */ + b = i + 1; + + /* Use the cache if it is there */ + if (p_cache) + p = *p_cache; + b += p; + + /* + * For every power of two below our bit number, bump our bit. + * + * We compare with (b + 1) because we have to compare with what b + * would be _if_ it were bumped up by the parity bit. Capice? + * + * p is set above. + */ + for (; (1 << p) < (b + 1); p++) + b++; + + if (p_cache) + *p_cache = p; + + return b; +} + +/* + * This is the low level encoder function. It can be called across + * multiple hunks just like the crc32 code. 'd' is the number of bits + * _in_this_hunk_. nr is the bit offset of this hunk. So, if you had + * two 512B buffers, you would do it like so: + * + * parity = ocfs2_hamming_encode(0, buf1, 512 * 8, 0); + * parity = ocfs2_hamming_encode(parity, buf2, 512 * 8, 512 * 8); + * + * If you just have one buffer, use ocfs2_hamming_encode_block(). + */ +u32 ocfs2_hamming_encode(u32 parity, void *data, unsigned int d, unsigned int nr) +{ + unsigned int i, b, p = 0; + + BUG_ON(!d); + + /* + * b is the hamming code bit number. Hamming code specifies a + * 1-based array, but C uses 0-based. So 'i' is for C, and 'b' is + * for the algorithm. + * + * The i++ in the for loop is so that the start offset passed + * to ocfs2_find_next_bit_set() is one greater than the previously + * found bit. + */ + for (i = 0; (i = ocfs2_find_next_bit(data, d, i)) < d; i++) + { + /* + * i is the offset in this hunk, nr + i is the total bit + * offset. + */ + b = calc_code_bit(nr + i, &p); + + /* + * Data bits in the resultant code are checked by + * parity bits that are part of the bit number + * representation. Huh? + * + * + * In other words, the parity bit at position 2^k + * checks bits in positions having bit k set in + * their binary representation. Conversely, for + * instance, bit 13, i.e. 1101(2), is checked by + * bits 1000(2) = 8, 0100(2)=4 and 0001(2) = 1. + * + * + * Note that 'k' is the _code_ bit number. 'b' in + * our loop. + */ + parity ^= b; + } + + /* While the data buffer was treated as little endian, the + * return value is in host endian. */ + return parity; +} + +u32 ocfs2_hamming_encode_block(void *data, unsigned int blocksize) +{ + return ocfs2_hamming_encode(0, data, blocksize * 8, 0); +} + +/* + * Like ocfs2_hamming_encode(), this can handle hunks. nr is the bit + * offset of the current hunk. If bit to be fixed is not part of the + * current hunk, this does nothing. + * + * If you only have one hunk, use ocfs2_hamming_fix_block(). + */ +void ocfs2_hamming_fix(void *data, unsigned int d, unsigned int nr, + unsigned int fix) +{ + unsigned int i, b; + + BUG_ON(!d); + + /* + * If the bit to fix has an hweight of 1, it's a parity bit. One + * busted parity bit is its own error. Nothing to do here. + */ + if (hweight32(fix) == 1) + return; + + /* + * nr + d is the bit right past the data hunk we're looking at. + * If fix after that, nothing to do + */ + if (fix >= calc_code_bit(nr + d, NULL)) + return; + + /* + * nr is the offset in the data hunk we're starting at. Let's + * start b at the offset in the code buffer. See hamming_encode() + * for a more detailed description of 'b'. + */ + b = calc_code_bit(nr, NULL); + /* If the fix is before this hunk, nothing to do */ + if (fix < b) + return; + + for (i = 0; i < d; i++, b++) + { + /* Skip past parity bits */ + while (hweight32(b) == 1) + b++; + + /* + * i is the offset in this data hunk. + * nr + i is the offset in the total data buffer. + * b is the offset in the total code buffer. + * + * Thus, when b == fix, bit i in the current hunk needs + * fixing. + */ + if (b == fix) + { + if (ocfs2_test_bit(i, data)) + ocfs2_clear_bit(i, data); + else + ocfs2_set_bit(i, data); + break; + } + } +} + +void ocfs2_hamming_fix_block(void *data, unsigned int blocksize, + unsigned int fix) +{ + ocfs2_hamming_fix(data, blocksize * 8, 0, fix); +} + +/* + * This function generates check information for a block. + * data is the block to be checked. bc is a pointer to the + * ocfs2_block_check structure describing the crc32 and the ecc. + * + * bc should be a pointer inside data, as the function will + * take care of zeroing it before calculating the check information. If + * bc does not point inside data, the caller must make sure any inline + * ocfs2_block_check structures are zeroed. + * + * The data buffer must be in on-disk endian (little endian for ocfs2). + * bc will be filled with little-endian values and will be ready to go to + * disk. + */ +void ocfs2_block_check_compute(void *data, size_t blocksize, + struct ocfs2_block_check *bc) +{ + u32 crc; + u32 ecc; + + memset(bc, 0, sizeof(struct ocfs2_block_check)); + + crc = crc32_le(~0, data, blocksize); + ecc = ocfs2_hamming_encode_block(data, blocksize); + + /* + * No ecc'd ocfs2 structure is larger than 4K, so ecc will be no + * larger than 16 bits. + */ + BUG_ON(ecc > USHORT_MAX); + + bc->bc_crc32e = cpu_to_le32(crc); + bc->bc_ecc = cpu_to_le16((u16)ecc); +} + +/* + * This function validates existing check information. Like _compute, + * the function will take care of zeroing bc before calculating check codes. + * If bc is not a pointer inside data, the caller must have zeroed any + * inline ocfs2_block_check structures. + * + * Again, the data passed in should be the on-disk endian. + */ +int ocfs2_block_check_validate(void *data, size_t blocksize, + struct ocfs2_block_check *bc) +{ + int rc = 0; + struct ocfs2_block_check check; + u32 crc, ecc; + + check.bc_crc32e = le32_to_cpu(bc->bc_crc32e); + check.bc_ecc = le16_to_cpu(bc->bc_ecc); + + memset(bc, 0, sizeof(struct ocfs2_block_check)); + + /* Fast path - if the crc32 validates, we're good to go */ + crc = crc32_le(~0, data, blocksize); + if (crc == check.bc_crc32e) + goto out; + + mlog(ML_ERROR, + "CRC32 failed: stored: %u, computed %u. Applying ECC.\n", + (unsigned int)check.bc_crc32e, (unsigned int)crc); + + /* Ok, try ECC fixups */ + ecc = ocfs2_hamming_encode_block(data, blocksize); + ocfs2_hamming_fix_block(data, blocksize, ecc ^ check.bc_ecc); + + /* And check the crc32 again */ + crc = crc32_le(~0, data, blocksize); + if (crc == check.bc_crc32e) + goto out; + + mlog(ML_ERROR, "Fixed CRC32 failed: stored: %u, computed %u\n", + (unsigned int)check.bc_crc32e, (unsigned int)crc); + + rc = -EIO; + +out: + bc->bc_crc32e = cpu_to_le32(check.bc_crc32e); + bc->bc_ecc = cpu_to_le16(check.bc_ecc); + + return rc; +} + +/* + * This function generates check information for a list of buffer_heads. + * bhs is the blocks to be checked. bc is a pointer to the + * ocfs2_block_check structure describing the crc32 and the ecc. + * + * bc should be a pointer inside data, as the function will + * take care of zeroing it before calculating the check information. If + * bc does not point inside data, the caller must make sure any inline + * ocfs2_block_check structures are zeroed. + * + * The data buffer must be in on-disk endian (little endian for ocfs2). + * bc will be filled with little-endian values and will be ready to go to + * disk. + */ +void ocfs2_block_check_compute_bhs(struct buffer_head **bhs, int nr, + struct ocfs2_block_check *bc) +{ + int i; + u32 crc, ecc; + + BUG_ON(nr < 0); + + if (!nr) + return; + + memset(bc, 0, sizeof(struct ocfs2_block_check)); + + for (i = 0, crc = ~0, ecc = 0; i < nr; i++) { + crc = crc32_le(crc, bhs[i]->b_data, bhs[i]->b_size); + /* + * The number of bits in a buffer is obviously b_size*8. + * The offset of this buffer is b_size*i, so the bit offset + * of this buffer is b_size*8*i. + */ + ecc = (u16)ocfs2_hamming_encode(ecc, bhs[i]->b_data, + bhs[i]->b_size * 8, + bhs[i]->b_size * 8 * i); + } + + /* + * No ecc'd ocfs2 structure is larger than 4K, so ecc will be no + * larger than 16 bits. + */ + BUG_ON(ecc > USHORT_MAX); + + bc->bc_crc32e = cpu_to_le32(crc); + bc->bc_ecc = cpu_to_le16((u16)ecc); +} + +/* + * This function validates existing check information on a list of + * buffer_heads. Like _compute_bhs, the function will take care of + * zeroing bc before calculating check codes. If bc is not a pointer + * inside data, the caller must have zeroed any inline + * ocfs2_block_check structures. + * + * Again, the data passed in should be the on-disk endian. + */ +int ocfs2_block_check_validate_bhs(struct buffer_head **bhs, int nr, + struct ocfs2_block_check *bc) +{ + int i, rc = 0; + struct ocfs2_block_check check; + u32 crc, ecc, fix; + + BUG_ON(nr < 0); + + if (!nr) + return 0; + + check.bc_crc32e = le32_to_cpu(bc->bc_crc32e); + check.bc_ecc = le16_to_cpu(bc->bc_ecc); + + memset(bc, 0, sizeof(struct ocfs2_block_check)); + + /* Fast path - if the crc32 validates, we're good to go */ + for (i = 0, crc = ~0; i < nr; i++) + crc = crc32_le(crc, bhs[i]->b_data, bhs[i]->b_size); + if (crc == check.bc_crc32e) + goto out; + + mlog(ML_ERROR, + "CRC32 failed: stored: %u, computed %u. Applying ECC.\n", + (unsigned int)check.bc_crc32e, (unsigned int)crc); + + /* Ok, try ECC fixups */ + for (i = 0, ecc = 0; i < nr; i++) { + /* + * The number of bits in a buffer is obviously b_size*8. + * The offset of this buffer is b_size*i, so the bit offset + * of this buffer is b_size*8*i. + */ + ecc = (u16)ocfs2_hamming_encode(ecc, bhs[i]->b_data, + bhs[i]->b_size * 8, + bhs[i]->b_size * 8 * i); + } + fix = ecc ^ check.bc_ecc; + for (i = 0; i < nr; i++) { + /* + * Try the fix against each buffer. It will only affect + * one of them. + */ + ocfs2_hamming_fix(bhs[i]->b_data, bhs[i]->b_size * 8, + bhs[i]->b_size * 8 * i, fix); + } + + /* And check the crc32 again */ + for (i = 0, crc = ~0; i < nr; i++) + crc = crc32_le(crc, bhs[i]->b_data, bhs[i]->b_size); + if (crc == check.bc_crc32e) + goto out; + + mlog(ML_ERROR, "Fixed CRC32 failed: stored: %u, computed %u\n", + (unsigned int)check.bc_crc32e, (unsigned int)crc); + + rc = -EIO; + +out: + bc->bc_crc32e = cpu_to_le32(check.bc_crc32e); + bc->bc_ecc = cpu_to_le16(check.bc_ecc); + + return rc; +} + +/* + * These are the main API. They check the superblock flag before + * calling the underlying operations. + * + * They expect the buffer(s) to be in disk format. + */ +void ocfs2_compute_meta_ecc(struct super_block *sb, void *data, + struct ocfs2_block_check *bc) +{ + 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; + + if (ocfs2_meta_ecc(OCFS2_SB(sb))) + rc = ocfs2_block_check_validate(data, sb->s_blocksize, bc); + + 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; + + if (ocfs2_meta_ecc(OCFS2_SB(sb))) + rc = ocfs2_block_check_validate_bhs(bhs, nr, bc); + + return rc; +} + -- cgit v1.2.3