mars/kernel/lib_log.h

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/*
* MARS Long Distance Replication Software
*
* This file is part of MARS project: http://schoebel.github.io/mars/
*
* Copyright (C) 2010-2014 Thomas Schoebel-Theuer
* Copyright (C) 2011-2014 1&1 Internet AG
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* 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.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
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/* Definitions for logfile format.
*
* This is meant for sharing between different transaction logger variants,
* and/or for sharing with userspace tools (e.g. logfile analyzers).
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* TODO: factor out some remaining kernelspace issues.
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*/
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#ifndef LIB_LOG_H
#define LIB_LOG_H
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#ifdef __KERNEL__
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#include "mars.h"
extern atomic_t global_mref_flying;
#endif
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/* The following structure is memory-only.
* Transfers to disk are indirectly via the
* format conversion functions below.
* The advantage is that even newer disk formats can be parsed
* by old code (of course, not all information / features will be
* available then).
*/
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#define log_header log_header_v1
struct log_header_v1 {
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struct lamport_time l_stamp;
struct lamport_time l_written;
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loff_t l_pos;
short l_len;
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short l_code;
unsigned int l_seq_nr;
int l_crc;
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};
#define FORMAT_VERSION 1 // version of disk format, currently there is no other one
#define CODE_UNKNOWN 0
#define CODE_WRITE_NEW 1
#define CODE_WRITE_OLD 2
#define START_MAGIC 0xa8f7e908d9177957ll
#define END_MAGIC 0x74941fb74ab5726dll
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#define START_OVERHEAD \
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( \
sizeof(START_MAGIC) + \
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sizeof(char) + \
sizeof(char) + \
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sizeof(short) + \
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sizeof(struct lamport_time) + \
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sizeof(loff_t) + \
sizeof(int) + \
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sizeof(int) + \
sizeof(short) + \
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sizeof(short) + \
0 \
)
#define END_OVERHEAD \
( \
sizeof(END_MAGIC) + \
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sizeof(int) + \
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sizeof(char) + \
3 + 4 /*spare*/ + \
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sizeof(struct lamport_time) + \
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0 \
)
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#define OVERHEAD (START_OVERHEAD + END_OVERHEAD)
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// TODO: make this bytesex-aware.
#define DATA_PUT(data,offset,val) \
do { \
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*((typeof(val)*)((data)+offset)) = val; \
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offset += sizeof(val); \
} while (0)
#define DATA_GET(data,offset,val) \
do { \
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val = *((typeof(val)*)((data)+offset)); \
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offset += sizeof(val); \
} while (0)
#define SCAN_TXT "at file_pos = %lld file_offset = %d scan_offset = %d (%lld) test_offset = %d (%lld) restlen = %d: "
#define SCAN_PAR file_pos, file_offset, offset, file_pos + file_offset + offset, i, file_pos + file_offset + i, restlen
static inline
int log_scan(void *buf, int len, loff_t file_pos, int file_offset, bool sloppy, struct log_header *lh, void **payload, int *payload_len, unsigned int *seq_nr)
{
bool dirty = false;
int offset;
int i;
*payload = NULL;
*payload_len = 0;
for (i = 0; i < len && i <= len - OVERHEAD; i += sizeof(long)) {
long long start_magic;
char format_version;
char valid_flag;
short total_len;
long long end_magic;
char valid_copy;
int restlen = 0;
int found_offset;
offset = i;
if (unlikely(i > 0 && !sloppy)) {
MARS_ERR(SCAN_TXT "detected a hole / bad data\n", SCAN_PAR);
return -EBADMSG;
}
DATA_GET(buf, offset, start_magic);
if (unlikely(start_magic != START_MAGIC)) {
if (start_magic != 0)
dirty = true;
continue;
}
restlen = len - i;
if (unlikely(restlen < START_OVERHEAD)) {
MARS_WRN(SCAN_TXT "magic found, but restlen is too small\n", SCAN_PAR);
return -EAGAIN;
}
DATA_GET(buf, offset, format_version);
if (unlikely(format_version != FORMAT_VERSION)) {
MARS_ERR(SCAN_TXT "found unknown data format %d\n", SCAN_PAR, (int)format_version);
return -EBADMSG;
}
DATA_GET(buf, offset, valid_flag);
if (unlikely(!valid_flag)) {
MARS_WRN(SCAN_TXT "data is explicitly marked invalid (was there a short write?)\n", SCAN_PAR);
continue;
}
DATA_GET(buf, offset, total_len);
if (unlikely(total_len > restlen)) {
MARS_WRN(SCAN_TXT "total_len = %d but available data restlen = %d. Was the logfile truncated?\n", SCAN_PAR, total_len, restlen);
return -EAGAIN;
}
memset(lh, 0, sizeof(struct log_header));
DATA_GET(buf, offset, lh->l_stamp.tv_sec);
DATA_GET(buf, offset, lh->l_stamp.tv_nsec);
DATA_GET(buf, offset, lh->l_pos);
DATA_GET(buf, offset, lh->l_len);
offset += 2; // skip spare
offset += 4; // skip spare
DATA_GET(buf, offset, lh->l_code);
offset += 2; // skip spare
found_offset = offset;
offset += lh->l_len;
restlen = len - offset;
if (unlikely(restlen < END_OVERHEAD)) {
MARS_WRN(SCAN_TXT "restlen %d is too small\n", SCAN_PAR, restlen);
return -EAGAIN;
}
DATA_GET(buf, offset, end_magic);
if (unlikely(end_magic != END_MAGIC)) {
MARS_WRN(SCAN_TXT "bad end_magic 0x%llx, is the logfile truncated?\n", SCAN_PAR, end_magic);
return -EBADMSG;
}
DATA_GET(buf, offset, lh->l_crc);
DATA_GET(buf, offset, valid_copy);
if (unlikely(valid_copy != 1)) {
MARS_WRN(SCAN_TXT "found data marked as uncompleted / invalid, len = %d, valid_flag = %d\n", SCAN_PAR, lh->l_len, (int)valid_copy);
return -EBADMSG;
}
// skip spares
offset += 3;
DATA_GET(buf, offset, lh->l_seq_nr);
DATA_GET(buf, offset, lh->l_written.tv_sec);
DATA_GET(buf, offset, lh->l_written.tv_nsec);
if (unlikely(lh->l_seq_nr > *seq_nr + 1 && lh->l_seq_nr && *seq_nr)) {
MARS_ERR(SCAN_TXT "record sequence number %u mismatch, expected was %u\n", SCAN_PAR, lh->l_seq_nr, *seq_nr + 1);
return -EBADMSG;
} else if (unlikely(lh->l_seq_nr != *seq_nr + 1 && lh->l_seq_nr && *seq_nr)) {
MARS_WRN(SCAN_TXT "record sequence number %u mismatch, expected was %u\n", SCAN_PAR, lh->l_seq_nr, *seq_nr + 1);
}
*seq_nr = lh->l_seq_nr;
if (lh->l_crc) {
unsigned char checksum[mars_digest_size];
mars_digest(checksum, buf + found_offset, lh->l_len);
if (unlikely(*(int*)checksum != lh->l_crc)) {
MARS_ERR(SCAN_TXT "data checksumming mismatch, length = %d\n", SCAN_PAR, lh->l_len);
return -EBADMSG;
}
}
// last check
if (unlikely(total_len != offset - i)) {
MARS_ERR(SCAN_TXT "internal size mismatch: %d != %d\n", SCAN_PAR, total_len, offset - i);
return -EBADMSG;
}
// Success...
*payload = buf + found_offset;
*payload_len = lh->l_len;
// don't cry when nullbytes have been skipped
if (i > 0 && dirty) {
MARS_WRN(SCAN_TXT "skipped %d dirty bytes to find valid data\n", SCAN_PAR, i);
}
return offset;
}
MARS_ERR("could not find any useful data within len=%d bytes\n", len);
return -EAGAIN;
}
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////////////////////////////////////////////////////////////////////////////
#ifdef __KERNEL__
/* Bookkeeping status between calls
*/
struct log_status {
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// interfacing
wait_queue_head_t *signal_event;
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int *signal_flag;
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// tunables
loff_t start_pos;
loff_t end_pos;
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int align_size; // alignment between requests
int chunk_size; // must be at least 8K (better 64k)
int max_size; // max payload length
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int io_prio;
bool do_crc;
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// informational
atomic_t mref_flying;
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int count;
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loff_t log_pos;
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struct lamport_time log_pos_stamp;
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// internal
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struct lamport_time tmp_pos_stamp;
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struct mars_input *input;
struct mars_brick *brick;
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struct mars_info info;
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int offset;
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int validflag_offset;
int reallen_offset;
int payload_offset;
int payload_len;
unsigned int seq_nr;
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struct mref_object *log_mref;
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struct mref_object *read_mref;
wait_queue_head_t event;
int error_code;
bool got;
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bool do_free;
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void *private;
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};
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void init_logst(struct log_status *logst, struct mars_input *input, loff_t start_pos, loff_t end_pos);
void exit_logst(struct log_status *logst);
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void log_flush(struct log_status *logst);
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void *log_reserve(struct log_status *logst, struct log_header *lh);
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bool log_finalize(struct log_status *logst, int len, void (*endio)(void *private, int error), void *private);
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int log_read(struct log_status *logst, bool sloppy, struct log_header *lh, void **payload, int *payload_len);
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/////////////////////////////////////////////////////////////////////////
// init
extern int init_log_format(void);
extern void exit_log_format(void);
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#endif
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#endif