blob: 429e6a8359a55a82671d8e950d9a53ee50f7598c [file] [log] [blame]
 // SPDX-License-Identifier: GPL-2.0-only /* -*- 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. */ #include #include #include #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 offset 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); } /* * Debugfs handling. */ #ifdef CONFIG_DEBUG_FS static int blockcheck_u64_get(void *data, u64 *val) { *val = *(u64 *)data; return 0; } DEFINE_SIMPLE_ATTRIBUTE(blockcheck_fops, blockcheck_u64_get, NULL, "%llu\n"); static struct dentry *blockcheck_debugfs_create(const char *name, struct dentry *parent, u64 *value) { return debugfs_create_file(name, S_IFREG | S_IRUSR, parent, value, &blockcheck_fops); } static void ocfs2_blockcheck_debug_remove(struct ocfs2_blockcheck_stats *stats) { if (stats) { debugfs_remove_recursive(stats->b_debug_dir); stats->b_debug_dir = NULL; } } static void ocfs2_blockcheck_debug_install(struct ocfs2_blockcheck_stats *stats, struct dentry *parent) { stats->b_debug_dir = debugfs_create_dir("blockcheck", parent); blockcheck_debugfs_create("blocks_checked", stats->b_debug_dir, &stats->b_check_count); blockcheck_debugfs_create("checksums_failed", stats->b_debug_dir, &stats->b_failure_count); blockcheck_debugfs_create("ecc_recoveries", stats->b_debug_dir, &stats->b_recover_count); } #else static inline void ocfs2_blockcheck_debug_install(struct ocfs2_blockcheck_stats *stats, struct dentry *parent) { } static inline void ocfs2_blockcheck_debug_remove(struct ocfs2_blockcheck_stats *stats) { } #endif /* CONFIG_DEBUG_FS */ /* Always-called wrappers for starting and stopping the debugfs files */ void ocfs2_blockcheck_stats_debugfs_install(struct ocfs2_blockcheck_stats *stats, struct dentry *parent) { ocfs2_blockcheck_debug_install(stats, parent); } void ocfs2_blockcheck_stats_debugfs_remove(struct ocfs2_blockcheck_stats *stats) { ocfs2_blockcheck_debug_remove(stats); } static void ocfs2_blockcheck_inc_check(struct ocfs2_blockcheck_stats *stats) { u64 new_count; if (!stats) return; spin_lock(&stats->b_lock); stats->b_check_count++; new_count = stats->b_check_count; spin_unlock(&stats->b_lock); if (!new_count) mlog(ML_NOTICE, "Block check count has wrapped\n"); } static void ocfs2_blockcheck_inc_failure(struct ocfs2_blockcheck_stats *stats) { u64 new_count; if (!stats) return; spin_lock(&stats->b_lock); stats->b_failure_count++; new_count = stats->b_failure_count; spin_unlock(&stats->b_lock); if (!new_count) mlog(ML_NOTICE, "Checksum failure count has wrapped\n"); } static void ocfs2_blockcheck_inc_recover(struct ocfs2_blockcheck_stats *stats) { u64 new_count; if (!stats) return; spin_lock(&stats->b_lock); stats->b_recover_count++; new_count = stats->b_recover_count; spin_unlock(&stats->b_lock); if (!new_count) mlog(ML_NOTICE, "ECC recovery count has wrapped\n"); } /* * These are the low-level APIs for using the ocfs2_block_check structure. */ /* * 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 > USHRT_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, struct ocfs2_blockcheck_stats *stats) { int rc = 0; u32 bc_crc32e; u16 bc_ecc; u32 crc, ecc; ocfs2_blockcheck_inc_check(stats); bc_crc32e = le32_to_cpu(bc->bc_crc32e); 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 == bc_crc32e) goto out; ocfs2_blockcheck_inc_failure(stats); mlog(ML_ERROR, "CRC32 failed: stored: 0x%x, computed 0x%x. Applying ECC.\n", (unsigned int)bc_crc32e, (unsigned int)crc); /* Ok, try ECC fixups */ ecc = ocfs2_hamming_encode_block(data, blocksize); ocfs2_hamming_fix_block(data, blocksize, ecc ^ bc_ecc); /* And check the crc32 again */ crc = crc32_le(~0, data, blocksize); if (crc == bc_crc32e) { ocfs2_blockcheck_inc_recover(stats); goto out; } mlog(ML_ERROR, "Fixed CRC32 failed: stored: 0x%x, computed 0x%x\n", (unsigned int)bc_crc32e, (unsigned int)crc); rc = -EIO; out: bc->bc_crc32e = cpu_to_le32(bc_crc32e); bc->bc_ecc = cpu_to_le16(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 > USHRT_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, struct ocfs2_blockcheck_stats *stats) { int i, rc = 0; u32 bc_crc32e; u16 bc_ecc; u32 crc, ecc, fix; BUG_ON(nr < 0); if (!nr) return 0; ocfs2_blockcheck_inc_check(stats); bc_crc32e = le32_to_cpu(bc->bc_crc32e); 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 == bc_crc32e) goto out; ocfs2_blockcheck_inc_failure(stats); mlog(ML_ERROR, "CRC32 failed: stored: %u, computed %u. Applying ECC.\n", (unsigned int)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 ^ 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 == bc_crc32e) { ocfs2_blockcheck_inc_recover(stats); goto out; } mlog(ML_ERROR, "Fixed CRC32 failed: stored: %u, computed %u\n", (unsigned int)bc_crc32e, (unsigned int)crc); rc = -EIO; out: bc->bc_crc32e = cpu_to_le32(bc_crc32e); bc->bc_ecc = cpu_to_le16(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; 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; }