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mars/kernel/lib_log.c
Thomas Schoebel-Theuer 34013933f0 lib_log: safeguard suspected coherence problems 2
2022-08-24 10:22:27 +02:00

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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.
*/
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/bio.h>
#include <linux/bitops.h>
//#define BRICK_DEBUGGING
//#define MARS_DEBUGGING
//#define IO_DEBUGGING
#include "lib_log.h"
#include "brick_wait.h"
__u32 enabled_log_compressions = 0;
__u32 used_log_compression = 0;
atomic_t global_mref_flying = ATOMIC_INIT(0);
EXPORT_SYMBOL_GPL(global_mref_flying);
void exit_logst(struct log_status *logst)
{
int count = 0;
log_flush(logst);
while (atomic_read(&logst->mref_flying) > 0) {
if (!count++)
MARS_DBG("waiting for IO terminating...");
brick_msleep(500);
}
if (logst->read_mref) {
MARS_DBG("putting read_mref\n");
GENERIC_INPUT_CALL_VOID(logst->input, mref_put, logst->read_mref);
logst->read_mref = NULL;
}
if (logst->log_mref) {
MARS_DBG("putting log_mref\n");
GENERIC_INPUT_CALL_VOID(logst->input, mref_put, logst->log_mref);
logst->log_mref = NULL;
}
}
EXPORT_SYMBOL_GPL(exit_logst);
void init_logst(struct log_status *logst, struct mars_input *input, loff_t start_pos, loff_t end_pos)
{
exit_logst(logst);
memset(logst, 0, sizeof(struct log_status));
logst->input = input;
logst->brick = input->brick;
logst->start_pos = start_pos;
logst->log_pos = start_pos;
logst->end_pos = end_pos;
init_waitqueue_head(&logst->event);
}
EXPORT_SYMBOL_GPL(init_logst);
#define MARS_LOG_CB_MAX 32
struct log_cb_info {
struct mref_object *mref;
struct log_status *logst;
struct semaphore mutex;
atomic_t refcount;
int nr_cb;
void (*endios[MARS_LOG_CB_MAX])(void *private, int error);
void *privates[MARS_LOG_CB_MAX];
};
static
void put_log_cb_info(struct log_cb_info *cb_info)
{
if (atomic_dec_and_test(&cb_info->refcount)) {
brick_mem_free(cb_info);
}
}
static
void _do_callbacks(struct log_cb_info *cb_info, int error)
{
int i;
down(&cb_info->mutex);
for (i = 0; i < cb_info->nr_cb; i++) {
void (*end_fn)(void *private, int error);
end_fn = cb_info->endios[i];
cb_info->endios[i] = NULL;
if (end_fn) {
end_fn(cb_info->privates[i], error);
}
}
up(&cb_info->mutex);
}
static
void log_write_endio(struct generic_callback *cb)
{
struct log_cb_info *cb_info = cb->cb_private;
struct log_status *logst;
LAST_CALLBACK(cb);
CHECK_PTR(cb_info, err);
if (cb_info->mref) {
mars_trace(cb_info->mref, "log_endio");
mars_log_trace(cb_info->mref);
}
logst = cb_info->logst;
CHECK_PTR(logst, done);
MARS_IO("nr_cb = %d\n", cb_info->nr_cb);
_do_callbacks(cb_info, cb->cb_error);
done:
put_log_cb_info(cb_info);
atomic_dec(&logst->mref_flying);
atomic_dec(&global_mref_flying);
if (logst->signal_event && logst->signal_flag)
brick_wake_flagged(logst->signal_event,
*(logst->signal_flag));
return;
err:
MARS_FAT("internal pointer corruption\n");
}
static
int log_compress(struct log_status *logst, int len,
int *padded_len,
__u32 *result_flags)
{
struct mref_object *mref = logst->log_mref;
void *inplace_buf;
void *compr_buf;
int compr_len;
int res;
if (unlikely(!mref || !mref->ref_data || len <= 0))
return 0;
compr_len = len + compress_overhead;
compr_buf = brick_mem_alloc(compr_len);
inplace_buf = mref->ref_data + logst->payload_offset;
res = mars_compress(inplace_buf, len,
compr_buf, compr_len,
enabled_log_compressions,
result_flags);
/* pad the resulting length */
if (res > 0) {
int pad_len = ((res + (_LOG_PAD - 1)) / _LOG_PAD) * _LOG_PAD;
/* Did compression pay off? */
if (pad_len < len) {
*padded_len = pad_len;
used_log_compression = *result_flags;
memcpy(inplace_buf, compr_buf, res);
} else {
*padded_len = len;
res = 0;
}
}
brick_mem_free(compr_buf);
return res;
}
void log_flush(struct log_status *logst)
{
struct mref_object *mref = logst->log_mref;
struct log_cb_info *cb_info;
int align_size;
int gap;
if (!mref || !logst->count)
return;
gap = 0;
align_size = (logst->align_size / PAGE_SIZE) * PAGE_SIZE;
if (align_size > 0) {
// round up to next alignment border
int align_offset = logst->offset & (align_size-1);
if (align_offset > 0) {
int restlen = mref->ref_len - logst->offset;
gap = align_size - align_offset;
if (unlikely(gap > restlen)) {
gap = restlen;
}
}
}
if (gap > 0) {
// don't leak information from kernelspace
memset(mref->ref_data + logst->offset, 0, gap);
logst->offset += gap;
}
mref->ref_len = logst->offset;
memcpy(&logst->log_pos_stamp, &logst->tmp_pos_stamp, sizeof(logst->log_pos_stamp));
cb_info = logst->private;
logst->private = NULL;
SETUP_CALLBACK(mref, log_write_endio, cb_info);
cb_info->logst = logst;
mref->ref_flags |= MREF_WRITE | MREF_MAY_WRITE;
mars_trace(mref, "log_flush");
atomic_inc(&logst->mref_flying);
atomic_inc(&global_mref_flying);
GENERIC_INPUT_CALL_VOID(logst->input, mref_io, mref);
GENERIC_INPUT_CALL_VOID(logst->input, mref_put, mref);
logst->log_pos += logst->offset;
logst->offset = 0;
logst->count = 0;
logst->log_mref = NULL;
put_log_cb_info(cb_info);
}
EXPORT_SYMBOL_GPL(log_flush);
void *log_reserve(struct log_status *logst, struct log_header *lh)
{
struct log_cb_info *cb_info = logst->private;
struct mref_object *mref;
void *data;
short total_len = lh->l_len + OVERHEAD;
int offset;
int status;
if (unlikely(lh->l_len <= 0 || lh->l_len > logst->max_size)) {
MARS_ERR("trying to write %d bytes, max allowed = %d\n", lh->l_len, logst->max_size);
goto err;
}
MARS_IO("reserving %d bytes at %lld\n", lh->l_len, logst->log_pos);
mref = logst->log_mref;
if ((mref && total_len > mref->ref_len - logst->offset)
|| !cb_info || cb_info->nr_cb >= MARS_LOG_CB_MAX) {
log_flush(logst);
}
mref = logst->log_mref;
if (!mref) {
if (unlikely(logst->private)) {
MARS_ERR("oops\n");
brick_mem_free(logst->private);
}
logst->private = brick_zmem_alloc(sizeof(struct log_cb_info));
if (unlikely(!logst->private)) {
MARS_ERR("no memory\n");
goto err;
}
cb_info = logst->private;
sema_init(&cb_info->mutex, 1);
atomic_set(&cb_info->refcount, 2);
mref = mars_alloc_mref(logst->brick);
if (unlikely(!mref)) {
MARS_ERR("no mref\n");
goto err;
}
cb_info->mref = mref;
mref->ref_pos = logst->log_pos;
mref->ref_len = logst->chunk_size ? logst->chunk_size : total_len;
mref->ref_flags = MREF_MAY_WRITE;
mref->ref_prio = logst->io_prio;
for (;;) {
status = GENERIC_INPUT_CALL(logst->input, mref_get, mref);
if (likely(status >= 0)) {
break;
}
if (status != -ENOMEM && status != -EAGAIN) {
MARS_ERR("mref_get() failed, status = %d\n", status);
goto err_free;
}
brick_msleep(100);
}
mars_trace(mref, "log_start");
if (unlikely(mref->ref_len < total_len)) {
MARS_ERR("ref_len = %d total_len = %d\n", mref->ref_len, total_len);
goto put;
}
logst->offset = 0;
logst->log_mref = mref;
}
offset = logst->offset;
data = mref->ref_data;
DATA_PUT(data, offset, START_MAGIC);
DATA_PUT(data, offset, (char)FORMAT_VERSION);
logst->validflag_offset = offset;
DATA_PUT(data, offset, (char)0); // valid_flag
logst->totallen_offset = offset;
DATA_PUT(data, offset, total_len); // start of next header
DATA_PUT(data, offset, lh->l_stamp.tv_sec);
DATA_PUT(data, offset, lh->l_stamp.tv_nsec);
DATA_PUT(data, offset, lh->l_pos);
logst->reallen_offset = offset;
DATA_PUT(data, offset, lh->l_len);
logst->decompresslen_offset = offset;
DATA_PUT(data, offset, (short)0); /* placeholder */
DATA_PUT(data, offset, (int)0); // spare
DATA_PUT(data, offset, lh->l_code);
DATA_PUT(data, offset, (short)0); // spare
// remember the last timestamp
memcpy(&logst->tmp_pos_stamp, &lh->l_stamp, sizeof(logst->tmp_pos_stamp));
logst->payload_offset = offset;
logst->payload_len = lh->l_len;
return data + offset;
put:
GENERIC_INPUT_CALL_VOID(logst->input, mref_put, mref);
logst->log_mref = NULL;
return NULL;
err_free:
mars_free_mref(mref);
if (logst->private) {
// TODO: if callbacks are already registered, call them here with some error code
brick_mem_free(logst->private);
}
err:
return NULL;
}
EXPORT_SYMBOL_GPL(log_reserve);
/* Unfortunately, the old logfile format had only 32 bit
* (4 byte) checksums.
* By converting the unused l_written to a checksum, we now
* can use 16 bytes.
* TODO: new backwards-compatible logfile format with even bigger
* checksums (32 bytes).
*/
static
void fold_crc(void *src, void *dst)
{
int i;
memset(dst, 0, LOG_CHKSUM_SIZE);
for (i = 0; i < MARS_DIGEST_SIZE; i += LOG_CHKSUM_SIZE) {
*(__u64*)dst ^= *(__u64*)(src + i);
*(__u64*)(dst + sizeof(__u64)) ^= *(__u64*)(src + i + sizeof(__u64));
}
}
bool log_finalize(struct log_status *logst, int len, void (*endio)(void *private, int error), void *private)
{
struct mref_object *mref = logst->log_mref;
struct log_cb_info *cb_info = logst->private;
void *data;
int offset;
int restlen;
int decompr_len;
int padded_len;
int nr_cb;
unsigned char crc[LOG_CHKSUM_SIZE] = {};
__u32 old_crc = 0;
__u32 check_flags;
__u16 crc_flags;
bool ok = false;
CHECK_PTR(mref, err);
if (unlikely(len > logst->payload_len)) {
MARS_ERR("trying to write more than reserved (%d > %d)\n", len, logst->payload_len);
goto err;
}
restlen = mref->ref_len - logst->offset;
if (unlikely(len + END_OVERHEAD > restlen)) {
MARS_ERR("trying to write more than available (%d > %d)\n", len, (int)(restlen - END_OVERHEAD));
goto err;
}
if (unlikely(!cb_info || cb_info->nr_cb >= MARS_LOG_CB_MAX)) {
MARS_ERR("too many endio() calls\n");
goto err;
}
data = mref->ref_data;
check_flags = 0;
/* Run the CRC on the _original_ data, before compression */
{
unsigned char checksum[MARS_DIGEST_SIZE];
check_flags |=
mars_digest(usable_digest_mask & ~disabled_log_digests,
&used_log_digest,
checksum,
data + logst->payload_offset, len);
if (check_flags & MREF_CHKSUM_MD5_OLD)
old_crc = *(__u32*)checksum;
else
fold_crc(checksum, crc);
}
/*
* Important: when somebody else would be later unable to decompress,
* it will then automatically result in a CRC mismatch.
*/
decompr_len = 0;
padded_len = len;
if (logst->do_compress) {
__u32 new_check_flags = check_flags;
int new_len = log_compress(logst, len,
&padded_len,
&new_check_flags);
/* When compression did not pay off, treat as uncompressed */
if (new_len > 0) {
check_flags = new_check_flags;
/* exchange the lengths */
decompr_len = len;
len = new_len;
}
}
/*
* We have only 16 flag bits in the traditional
* logfile format, which is in production over
* years. To remain compatible, we strip off
* non-checksum related bits.
*/
crc_flags = check_flags >> _MREF_CHKSUM_MD5_OLD;
/* Correct the length in the header.
*/
offset = logst->decompresslen_offset;
DATA_PUT(data, offset, (short)decompr_len);
offset = logst->reallen_offset;
DATA_PUT(data, offset, (short)len);
offset = logst->totallen_offset;
DATA_PUT(data, offset, (short)(padded_len + OVERHEAD));
/* Write the trailer.
*/
offset = logst->payload_offset + padded_len;
DATA_PUT(data, offset, END_MAGIC);
DATA_PUT(data, offset, old_crc);
DATA_PUT(data, offset, (char)1); // valid_flag copy
DATA_PUT(data, offset, (char)0); // spare
DATA_PUT(data, offset, crc_flags);
DATA_PUT(data, offset, logst->seq_nr + 1);
memcpy(data + offset, crc, LOG_CHKSUM_SIZE);
offset += LOG_CHKSUM_SIZE;
if (unlikely(offset > mref->ref_len)) {
MARS_FAT("length calculation was wrong: %d > %d\n", offset, mref->ref_len);
goto err;
}
logst->offset = offset;
/* This must come last. In case of incomplete
* or even overlapping disk transfers, this indicates
* the completeness / integrity of the payload at
* the time of starting the transfer.
*/
offset = logst->validflag_offset;
barrier();
DATA_PUT(data, offset, (char)1);
nr_cb = cb_info->nr_cb++;
cb_info->endios[nr_cb] = endio;
cb_info->privates[nr_cb] = private;
// report success
logst->seq_nr++;
logst->count++;
ok = true;
err:
return ok;
}
EXPORT_SYMBOL_GPL(log_finalize);
static
void log_read_endio(struct generic_callback *cb)
{
struct log_status *logst = cb->cb_private;
LAST_CALLBACK(cb);
CHECK_PTR(logst, err);
logst->posix_error_code = cb->cb_error;
logst->got = true;
brick_wake_smp(&logst->event);
return;
err:
MARS_FAT("internal pointer corruption\n");
}
int log_read(struct log_status *logst,
bool sloppy,
struct log_header *lh,
void **payload, int *payload_len,
void **dealloc)
{
struct mref_object *mref;
int old_offset;
int status;
*dealloc = NULL;
restart:
status = 0;
mref = logst->read_mref;
if (!mref || logst->do_free) {
loff_t this_len;
if (mref) {
GENERIC_INPUT_CALL_VOID(logst->input, mref_put, mref);
logst->read_mref = NULL;
logst->log_pos += logst->offset;
logst->offset = 0;
}
this_len = logst->end_pos - logst->log_pos;
if (this_len > logst->chunk_size) {
this_len = logst->chunk_size;
} else if (unlikely(this_len <= 0)) {
MARS_ERR("tried bad IO len %lld, start_pos = %lld log_pos = %lld end_pos = %lld\n", this_len, logst->start_pos, logst->log_pos, logst->end_pos);
status = -EOVERFLOW;
goto done;
}
mref = mars_alloc_mref(logst->brick);
if (unlikely(!mref)) {
MARS_ERR("no mref\n");
goto done;
}
mref->ref_pos = logst->log_pos;
mref->ref_len = this_len;
mref->ref_prio = logst->io_prio;
status = GENERIC_INPUT_CALL(logst->input, mref_get, mref);
if (unlikely(status < 0)) {
if (status != -ENODATA) {
MARS_ERR("mref_get() failed, status = %d\n", status);
}
goto done_free;
}
if (unlikely(mref->ref_len <= OVERHEAD)) { // EOF
status = 0;
goto done_put;
}
SETUP_CALLBACK(mref, log_read_endio, logst);
logst->offset = 0;
logst->got = false;
logst->do_free = false;
GENERIC_INPUT_CALL_VOID(logst->input, mref_io, mref);
brick_wait_smp(logst->event,
logst->got,
60 * HZ);
status = -ETIME;
if (!logst->got)
goto done_put;
status = logst->posix_error_code;
if (status < 0)
goto done_put;
if (mref->ref_len < this_len) {
/* Short read. May happen when logfiles are
* truncated underneath.
*/
logst->end_pos = logst->log_pos + mref->ref_len;
}
logst->read_mref = mref;
}
status = log_scan(mref->ref_data + logst->offset,
mref->ref_len - logst->offset,
mref->ref_pos,
logst->offset,
sloppy,
lh,
payload,
payload_len,
dealloc,
&logst->seq_nr,
&logst->mars_error_code,
&logst->byte_code);
if (unlikely(status == 0)) {
MARS_ERR("bad logfile scan\n");
status = -EINVAL;
if (!logst->mars_error_code)
logst->mars_error_code = -MARS_ERR_NOSCAN;
goto done_put;
}
if (unlikely(status < 0)) {
goto done_put;
}
// memoize success
logst->offset += status;
if (logst->offset + (logst->max_size + OVERHEAD) * 2 >= mref->ref_len) {
logst->do_free = true;
}
done:
if (status == -ENODATA) {
status = 0; // indicates EOF
}
return status;
done_put:
old_offset = logst->offset;
if (mref) {
GENERIC_INPUT_CALL_VOID(logst->input, mref_put, mref);
logst->read_mref = NULL;
logst->log_pos += logst->offset;
logst->offset = 0;
}
if (status == -EAGAIN && old_offset > 0) {
if (*dealloc) {
brick_mem_free(*dealloc);
}
/* safeguard any suspected coherence problems */
smp_mb();
goto restart;
}
goto done;
done_free:
if (mref) {
mars_free_mref(mref);
}
logst->read_mref = NULL;
goto done;
}
static
int _check_crc(struct log_header *lh,
void *crc,
void *crc_buf,
int crc_len,
__u32 check_flags,
int *mars_error_code)
{
__u32 invalid_check_flags;
bool is_invalid = false;
bool did_simple_retry = false;
int did_iterative_retry = 0;
int bit;
int res;
retry:
res = -EBADMSG;
if (check_flags & (MREF_CHKSUM_ANY - MREF_CHKSUM_MD5_OLD)) {
unsigned char checksum[MARS_DIGEST_SIZE];
unsigned char check_crc[LOG_CHKSUM_SIZE];
mars_digest(check_flags,
&used_log_digest,
checksum,
crc_buf, crc_len);
fold_crc(checksum, check_crc);
if (!memcmp(crc, check_crc, LOG_CHKSUM_SIZE))
res = 0;
} else if (lh->l_crc_old) {
unsigned char checksum[MARS_DIGEST_SIZE];
__u32 old_crc;
mars_digest(check_flags,
&used_log_digest,
checksum,
crc_buf, crc_len);
old_crc = *(int*)checksum;
if (old_crc == lh->l_crc_old)
res = 0;
} else if (!did_iterative_retry) {
invalid_check_flags = check_flags;
is_invalid = true;
}
/* simple retry method */
if (unlikely(res && !did_simple_retry)) {
did_simple_retry = true;
MARS_WRN("RETRY crc check flags=0x%x crc_len=%d\n",
check_flags, crc_len);
check_flags |= usable_digest_mask;
cond_resched();
/* safeguard any suspected coherence problems */
smp_mb();
goto retry;
}
/* when simple retry failed: try the painful iterative method */
if (unlikely(res)) {
/* We are desperate. We want to recover as much data
* as possible. Performance does no longer matter.
* Try to _wildly_ _guess_ what check_flags might by usable.
*/
if (!did_iterative_retry) {
bit = find_first_bit((void *)&usable_digest_mask,
sizeof(usable_digest_mask));
} else {
int next_bit =
find_next_bit((void *)&usable_digest_mask,
sizeof(usable_digest_mask),
bit + 1);
if (next_bit <= bit)
goto failed;
bit = next_bit;
}
if (bit >= 32)
goto failed;
check_flags = (1 << bit);
if (!(check_flags & usable_digest_mask))
goto failed;
did_iterative_retry++;
cond_resched();
/* safeguard any suspected coherence problems */
smp_mb();
goto retry;
failed:
MARS_WRN("ITERATIVE RETRY %d failed\n",
did_iterative_retry);
}
if (is_invalid) {
if (!*mars_error_code)
*mars_error_code = -MARS_ERR_CRC_FLAGS;
MARS_ERR("Found invalid crc flags=0x%x retried=%d+%d\n",
invalid_check_flags,
did_simple_retry, did_iterative_retry);
} else if (res < 0 && !*mars_error_code)
*mars_error_code = -MARS_ERR_CRC_MISMATCH;
return res;
}
static
int classify_bad_magic(unsigned long long this_magic,
unsigned char *found_byte_code,
int *mars_error_code)
{
unsigned long long shifter;
unsigned char pattern;
unsigned char byte;
int j;
/* Variant 1:
* Zero is assumed to be recoverable.
*/
if (!this_magic)
return -ERESTART;
/* Variant 2:
* Repeated bytewise patterns are assumed
* to point at
* (a) uninitialized (or defective) disk data.
* (b) problems in RAID hardware, drivers, DMA, etc.
* (c) CONFIG_DEBUG_PAGEALLOC or similar
* kernel-level sisters (also MARS-specific
* ones like CONFIG_MARS_DEBUG_MEM and
* sisters).
*/
shifter = this_magic;
pattern = (unsigned char)shifter;
for (j = 1; j < sizeof(shifter); j++) {
shifter >>= 8;
byte = shifter;
if (byte != pattern)
goto no_repeat;
}
*found_byte_code = byte;
if (!*mars_error_code)
*mars_error_code = -MARS_ERR_MAGIC_REPEATED;
return -EBADMSG;
no_repeat:
/* Last resort:
* not enough knowledge what might have happened before.
*/
if (!*mars_error_code)
*mars_error_code = -MARS_ERR_MAGIC_BAD;
return -EBADRQC;
}
#define RECORD_ERR(code) \
if (!*mars_error_code) \
*mars_error_code = (code)
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,
void **dealloc,
unsigned int *seq_nr,
int *mars_error_code,
int *byte_code)
{
bool dirty = false;
unsigned char start_byte_code = 0;
int offset;
int i;
*payload = NULL;
*payload_len = 0;
for (i = 0; i < len && i <= len - OVERHEAD; i += sizeof(long)) {
unsigned char crc[LOG_CHKSUM_SIZE];
unsigned long long start_magic;
char format_version;
char valid_flag;
short total_len;
unsigned long long end_magic;
char valid_copy;
__u32 check_flags;
int restlen = 0;
int crc_len;
int decompr_len;
int found_offset;
int crc_status;
int advance;
void *new_buf = NULL;
void *crc_buf;
offset = i;
if (unlikely(i > 0 && !sloppy)) {
MARS_ERR(SCAN_TXT "detected a hole / bad data >= %d\n",
SCAN_PAR, i);
RECORD_ERR(-MARS_ERR_SCAN_HOLE);
return -EBADMSG;
}
DATA_GET(buf, offset, start_magic);
if (unlikely(start_magic != START_MAGIC)) {
/* Skip any zeros without notice.
* This may be used for future extensions, like
* padding at certain places of logfiles.
*/
if (start_magic != 0) {
dirty = true;
classify_bad_magic(start_magic,
&start_byte_code,
mars_error_code);
if (start_byte_code && !*byte_code) {
*byte_code = start_byte_code;
MARS_WRN(SCAN_TXT "found repeated byte pattern 0x%02x",
SCAN_PAR,
start_byte_code);
}
}
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);
RECORD_ERR(-MARS_ERR_SCAN_FORMAT);
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);
RECORD_ERR(-MARS_ERR_SCAN_INVAL);
continue;
}
DATA_GET(buf, offset, total_len);
if (unlikely(!total_len)) {
MARS_WRN(SCAN_TXT "advance is zero\n",
SCAN_PAR);
RECORD_ERR(-MARS_ERR_SCAN_ZERO);
return -ERESTART;
}
if (unlikely(total_len < 0)) {
MARS_WRN(SCAN_TXT "advance %d is wrong\n",
SCAN_PAR, total_len);
RECORD_ERR(-MARS_ERR_SCAN_NEGATIVE);
return -EBADMSG;
}
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);
RECORD_ERR(-MARS_ERR_SCAN_BADLEN);
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);
DATA_GET(buf, offset, lh->l_decompress_len);
offset += 4; // skip spare
DATA_GET(buf, offset, lh->l_code);
offset += 2; // skip spare
found_offset = offset;
advance = total_len - OVERHEAD;
if (unlikely(advance <= 0)) {
MARS_WRN(SCAN_TXT "advance %d is too small\n",
SCAN_PAR, advance);
RECORD_ERR(-MARS_ERR_SCAN_ADVANCE);
return -ERESTART;
}
offset += advance;
restlen = len - offset;
if (unlikely(restlen < END_OVERHEAD)) {
MARS_WRN(SCAN_TXT "restlen %d is too small\n", SCAN_PAR, restlen);
RECORD_ERR(-MARS_ERR_SCAN_RESTLEN);
return -EAGAIN;
}
DATA_GET(buf, offset, end_magic);
if (unlikely(end_magic != END_MAGIC)) {
unsigned char end_byte_code = 0;
int err;
MARS_WRN(SCAN_TXT "bad end_magic 0x%llx, is the logfile truncated?\n",
SCAN_PAR,
end_magic);
err = classify_bad_magic(end_magic,
&end_byte_code,
mars_error_code);
if (end_byte_code && !*byte_code) {
*byte_code = end_byte_code;
MARS_WRN(SCAN_TXT "found repeated byte pattern 0x%02x",
SCAN_PAR,
end_byte_code);
}
return err;
}
DATA_GET(buf, offset, lh->l_crc_old);
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);
RECORD_ERR(-MARS_ERR_SCAN_INCOMPL);
return -EBADMSG;
}
// skip spares
offset += 1;
DATA_GET(buf, offset, lh->l_crc_flags);
DATA_GET(buf, offset, lh->l_seq_nr);
memcpy(crc, buf + offset, LOG_CHKSUM_SIZE);
offset += LOG_CHKSUM_SIZE;
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);
RECORD_ERR(-MARS_ERR_SCAN_SEQ_FW);
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);
/* Theoretically, a backskip of sequence number
* can be tolerated, if it is really true.
* We may use this in future, e.g. for propagation
* of updated records.
* It may also happen in some future record patterns.
*/
RECORD_ERR(-MARS_ERR_SCAN_SEQ_BW);
}
*seq_nr = lh->l_seq_nr;
/*
* We have only 16 flag bits in the traditional
* logfile format, which is in production over
* years. To remain compatible, we strip off
* non-checksum related bits.
*/
check_flags =
(((__u32)lh->l_crc_flags) << _MREF_CHKSUM_MD5_OLD) &
(available_digest_mask | available_compression_mask);
/* compatibility with old logfiles during upgrade */
if (!check_flags)
check_flags = MREF_CHKSUM_MD5_OLD;
decompr_len = lh->l_decompress_len;
crc_len = lh->l_len;
if (decompr_len > 0 &&
unlikely(decompr_len > MARS_MAX_COMPR_SIZE ||
decompr_len <= crc_len ||
(decompr_len % 512) != 0)) {
MARS_ERR(SCAN_TXT "implausible decompr_len: %d ~~ %d\n",
SCAN_PAR, decompr_len, crc_len);
RECORD_ERR(-MARS_ERR_DECOMPR_BADLEN);
return -EBADMSG;
}
if (unlikely(crc_len > MARS_MAX_COMPR_SIZE)) {
MARS_ERR(SCAN_TXT "implausible crc_len: %d > %ld\n",
SCAN_PAR, crc_len, MARS_MAX_COMPR_SIZE);
RECORD_ERR(-MARS_ERR_DECOMPR_TOOBIG);
return -EBADMSG;
}
crc_buf = buf + found_offset;
if ((check_flags & MREF_COMPRESS_ANY) &&
decompr_len > 0) {
new_buf =
mars_decompress(crc_buf, crc_len,
NULL, decompr_len,
check_flags);
if (likely(new_buf)) {
*dealloc = new_buf;
crc_buf = new_buf;
crc_len = decompr_len;
} else {
MARS_ERR(SCAN_TXT "decompression 0x%x failure len=%d/%d\n",
SCAN_PAR, check_flags,
crc_len, decompr_len);
RECORD_ERR(-MARS_ERR_DECOMPR_FAIL);
return -EBADMSG;
}
}
crc_status =
_check_crc(lh,
crc,
crc_buf,
crc_len,
check_flags,
mars_error_code);
if (crc_status) {
MARS_ERR(SCAN_TXT
"data checksumming mismatch, flags=0x%x len=%d/%d err=%d\n",
SCAN_PAR,
check_flags,
lh->l_len, crc_len,
crc_status);
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);
RECORD_ERR(-MARS_ERR_SCAN_SIZE);
return -EBADMSG;
}
// Success...
*payload = crc_buf;
*payload_len = crc_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);
if (start_byte_code && !*byte_code) {
*byte_code = start_byte_code;
MARS_WRN("found repeated byte pattern 0x%02x",
start_byte_code);
}
}
return offset;
}
MARS_ERR("could not find any useful data within len=%d bytes\n", len);
RECORD_ERR(-MARS_ERR_SCAN_GARBAGE);
return -EAGAIN;
}
////////////////// module init stuff /////////////////////////
int __init init_log_format(void)
{
MARS_INF("init_log_format()\n");
return 0;
}
void exit_log_format(void)
{
MARS_INF("exit_log_format()\n");
}
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