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osd-contiki/core/cfs/cfs-coffee.c

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/*
* Copyright (c) 2008, 2009, Swedish Institute of Computer Science
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the Institute nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* This file is part of the Contiki operating system.
*
*/
/**
* \file
* Coffee: A file system for a variety of storage types in
* memory-constrained devices.
*
* For further information, see "Enabling Large-Scale Storage in
* Sensor Networks with the Coffee File System" in the proceedings
* of ACM/IEEE IPSN 2009.
*
* \author
* Nicolas Tsiftes <nvt@sics.se>
*/
#include <limits.h>
#include <string.h>
#define DEBUG 0
#if DEBUG
#include <stdio.h>
#define PRINTF(...) printf(__VA_ARGS__)
#else
#define PRINTF(...)
#endif
#include "contiki-conf.h"
#include "cfs/cfs.h"
#include "cfs-coffee-arch.h"
#include "cfs/cfs-coffee.h"
/* Micro logs enable modifications on storage types that do not support
in-place updates. This applies primarily to flash memories. */
#ifndef COFFEE_MICRO_LOGS
#define COFFEE_MICRO_LOGS 1
#endif
/* If the files are expected to be appended to only, this parameter
can be set to save some code space. */
#ifndef COFFEE_APPEND_ONLY
#define COFFEE_APPEND_ONLY 0
#endif
#if COFFEE_MICRO_LOGS && COFFEE_APPEND_ONLY
#error "Cannot have COFFEE_APPEND_ONLY set when COFFEE_MICRO_LOGS is set."
#endif
/* I/O semantics can be set on file descriptors in order to optimize
file access on certain storage types. */
#ifndef COFFEE_IO_SEMANTICS
#define COFFEE_IO_SEMANTICS 0
#endif
/*
* Prevent sectors from being erased directly after file removal.
* This will level the wear across sectors better, but may lead
* to longer garbage collection procedures.
*/
#ifndef COFFEE_EXTENDED_WEAR_LEVELLING
#define COFFEE_EXTENDED_WEAR_LEVELLING 1
#endif
#if COFFEE_START & (COFFEE_SECTOR_SIZE - 1)
#error COFFEE_START must point to the first byte in a sector.
#endif
#define COFFEE_FD_FREE 0x0
#define COFFEE_FD_READ 0x1
#define COFFEE_FD_WRITE 0x2
#define COFFEE_FD_APPEND 0x4
#define COFFEE_FILE_MODIFIED 0x1
#define INVALID_PAGE ((coffee_page_t)-1)
#define UNKNOWN_OFFSET ((cfs_offset_t)-1)
#define REMOVE_LOG 1
#define CLOSE_FDS 1
#define ALLOW_GC 1
/* "Greedy" garbage collection erases as many sectors as possible. */
#define GC_GREEDY 0
/* "Reluctant" garbage collection stops after erasing one sector. */
#define GC_RELUCTANT 1
/* File descriptor macros. */
#define FD_VALID(fd) ((fd) >= 0 && (fd) < COFFEE_FD_SET_SIZE && \
coffee_fd_set[(fd)].flags != COFFEE_FD_FREE)
#define FD_READABLE(fd) (coffee_fd_set[(fd)].flags & CFS_READ)
#define FD_WRITABLE(fd) (coffee_fd_set[(fd)].flags & CFS_WRITE)
#define FD_APPENDABLE(fd) (coffee_fd_set[(fd)].flags & CFS_APPEND)
/* File object macros. */
#define FILE_MODIFIED(file) ((file)->flags & COFFEE_FILE_MODIFIED)
#define FILE_FREE(file) ((file)->max_pages == 0)
#define FILE_UNREFERENCED(file) ((file)->references == 0)
/* File header flags. */
#define HDR_FLAG_VALID 0x01 /* Completely written header. */
#define HDR_FLAG_ALLOCATED 0x02 /* Allocated file. */
#define HDR_FLAG_OBSOLETE 0x04 /* File marked for GC. */
#define HDR_FLAG_MODIFIED 0x08 /* Modified file, log exists. */
#define HDR_FLAG_LOG 0x10 /* Log file. */
#define HDR_FLAG_ISOLATED 0x20 /* Isolated page. */
/* File header macros. */
#define CHECK_FLAG(hdr, flag) ((hdr).flags & (flag))
#define HDR_VALID(hdr) CHECK_FLAG(hdr, HDR_FLAG_VALID)
#define HDR_ALLOCATED(hdr) CHECK_FLAG(hdr, HDR_FLAG_ALLOCATED)
#define HDR_FREE(hdr) !HDR_ALLOCATED(hdr)
#define HDR_LOG(hdr) CHECK_FLAG(hdr, HDR_FLAG_LOG)
#define HDR_MODIFIED(hdr) CHECK_FLAG(hdr, HDR_FLAG_MODIFIED)
#define HDR_ISOLATED(hdr) CHECK_FLAG(hdr, HDR_FLAG_ISOLATED)
#define HDR_OBSOLETE(hdr) CHECK_FLAG(hdr, HDR_FLAG_OBSOLETE)
#define HDR_ACTIVE(hdr) (HDR_ALLOCATED(hdr) && \
!HDR_OBSOLETE(hdr) && \
!HDR_ISOLATED(hdr))
/* Shortcuts derived from the hardware-dependent configuration of Coffee. */
#define COFFEE_SECTOR_COUNT \
(coffee_page_t)(COFFEE_SIZE / COFFEE_SECTOR_SIZE)
#define COFFEE_PAGE_COUNT \
((coffee_page_t)(COFFEE_SIZE / COFFEE_PAGE_SIZE))
#define COFFEE_PAGES_PER_SECTOR \
((coffee_page_t)(COFFEE_SECTOR_SIZE / COFFEE_PAGE_SIZE))
/* This structure is used for garbage collection statistics. */
struct sector_status {
coffee_page_t active;
coffee_page_t obsolete;
coffee_page_t free;
};
/* The structure of cached file objects. */
struct file {
cfs_offset_t end;
coffee_page_t page;
coffee_page_t max_pages;
int16_t record_count;
uint8_t references;
uint8_t flags;
};
/* The file descriptor structure. */
struct file_desc {
cfs_offset_t offset;
struct file *file;
uint8_t flags;
#if COFFEE_IO_SEMANTICS
uint8_t io_flags;
#endif
};
/* The file header structure mimics the representation of file headers
in the physical storage medium. */
struct file_header {
coffee_page_t log_page;
uint16_t log_records;
uint16_t log_record_size;
coffee_page_t max_pages;
uint8_t deprecated_eof_hint;
uint8_t flags;
char name[COFFEE_NAME_LENGTH];
};
/* This is needed because of a buggy compiler. */
struct log_param {
cfs_offset_t offset;
const char *buf;
uint16_t size;
};
/*
* Variables that keep track of opened files and internal
* optimization information for Coffee.
*/
static struct file coffee_files[COFFEE_MAX_OPEN_FILES];
static struct file_desc coffee_fd_set[COFFEE_FD_SET_SIZE];
static coffee_page_t next_free;
static char gc_wait;
/*---------------------------------------------------------------------------*/
static void
write_header(struct file_header *hdr, coffee_page_t page)
{
hdr->flags |= HDR_FLAG_VALID;
COFFEE_WRITE(hdr, sizeof(*hdr), page * COFFEE_PAGE_SIZE);
}
/*---------------------------------------------------------------------------*/
static void
read_header(struct file_header *hdr, coffee_page_t page)
{
COFFEE_READ(hdr, sizeof(*hdr), page * COFFEE_PAGE_SIZE);
#if DEBUG
if(HDR_ACTIVE(*hdr) && !HDR_VALID(*hdr)) {
PRINTF("Invalid header at page %u!\n", (unsigned)page);
}
#endif
}
/*---------------------------------------------------------------------------*/
static cfs_offset_t
absolute_offset(coffee_page_t page, cfs_offset_t offset)
{
return page * COFFEE_PAGE_SIZE + sizeof(struct file_header) + offset;
}
/*---------------------------------------------------------------------------*/
static coffee_page_t
get_sector_status(coffee_page_t sector, struct sector_status *stats)
{
static coffee_page_t skip_pages;
static char last_pages_are_active;
struct file_header hdr;
coffee_page_t active, obsolete, free;
coffee_page_t sector_start, sector_end;
coffee_page_t page;
memset(stats, 0, sizeof(*stats));
active = obsolete = free = 0;
/*
* get_sector_status() is an iterative function using local static
* state. It therefore requires that the caller starts iterating from
* sector 0 in order to reset the internal state.
*/
if(sector == 0) {
skip_pages = 0;
last_pages_are_active = 0;
}
sector_start = sector * COFFEE_PAGES_PER_SECTOR;
sector_end = sector_start + COFFEE_PAGES_PER_SECTOR;
/*
* Account for pages belonging to a file starting in a previous
* segment that extends into this segment. If the whole segment is
* covered, we do not need to continue counting pages in this iteration.
*/
if(last_pages_are_active) {
if(skip_pages >= COFFEE_PAGES_PER_SECTOR) {
stats->active = COFFEE_PAGES_PER_SECTOR;
skip_pages -= COFFEE_PAGES_PER_SECTOR;
return 0;
}
active = skip_pages;
} else {
if(skip_pages >= COFFEE_PAGES_PER_SECTOR) {
stats->obsolete = COFFEE_PAGES_PER_SECTOR;
skip_pages -= COFFEE_PAGES_PER_SECTOR;
return skip_pages >= COFFEE_PAGES_PER_SECTOR ? 0 : skip_pages;
}
obsolete = skip_pages;
}
/* Determine the amount of pages of each type that have not been
accounted for yet in the current sector. */
for(page = sector_start + skip_pages; page < sector_end;) {
read_header(&hdr, page);
last_pages_are_active = 0;
if(HDR_ACTIVE(hdr)) {
last_pages_are_active = 1;
page += hdr.max_pages;
active += hdr.max_pages;
} else if(HDR_ISOLATED(hdr)) {
page++;
obsolete++;
} else if(HDR_OBSOLETE(hdr)) {
page += hdr.max_pages;
obsolete += hdr.max_pages;
} else {
free = sector_end - page;
break;
}
}
/*
* Determine the amount of pages in the following sectors that
* should be remembered for the next iteration. This is necessary
* because no file page except the first contains information
* about what type of page it is. A side effect of remembering this
* amount is that there is no need to read in the headers of each
* of these pages from the storage.
*/
skip_pages = active + obsolete + free - COFFEE_PAGES_PER_SECTOR;
if(skip_pages > 0) {
if(last_pages_are_active) {
active = COFFEE_PAGES_PER_SECTOR - obsolete;
} else {
obsolete = COFFEE_PAGES_PER_SECTOR - active;
}
}
stats->active = active;
stats->obsolete = obsolete;
stats->free = free;
/*
* To avoid unnecessary page isolation, we notify the caller that
* "skip_pages" pages should be isolated only if the current file extent
* ends in the next sector. If the file extent ends in a more distant
* sector, however, the garbage collection can free the next sector
* immediately without requiring page isolation.
*/
return (last_pages_are_active || (skip_pages >= COFFEE_PAGES_PER_SECTOR)) ?
0 : skip_pages;
}
/*---------------------------------------------------------------------------*/
static void
isolate_pages(coffee_page_t start, coffee_page_t skip_pages)
{
struct file_header hdr;
coffee_page_t page;
/* Split an obsolete file starting in the previous sector and mark
the following pages as isolated. */
memset(&hdr, 0, sizeof(hdr));
hdr.flags = HDR_FLAG_ALLOCATED | HDR_FLAG_ISOLATED;
/* Isolation starts from the next sector. */
for(page = 0; page < skip_pages; page++) {
write_header(&hdr, start + page);
}
PRINTF("Coffee: Isolated %u pages starting in sector %d\n",
(unsigned)skip_pages, (int)start / COFFEE_PAGES_PER_SECTOR);
}
/*---------------------------------------------------------------------------*/
static void
collect_garbage(int mode)
{
coffee_page_t sector;
struct sector_status stats;
coffee_page_t first_page, isolation_count;
PRINTF("Coffee: Running the garbage collector in %s mode\n",
mode == GC_RELUCTANT ? "reluctant" : "greedy");
/*
* The garbage collector erases as many sectors as possible. A sector is
* erasable if there are only free or obsolete pages in it.
*/
for(sector = 0; sector < COFFEE_SECTOR_COUNT; sector++) {
isolation_count = get_sector_status(sector, &stats);
PRINTF("Coffee: Sector %u has %u active, %u obsolete, and %u free pages.\n",
(unsigned)sector, (unsigned)stats.active,
(unsigned)stats.obsolete, (unsigned)stats.free);
if(stats.active > 0) {
continue;
}
if((mode == GC_RELUCTANT && stats.free == 0) ||
(mode == GC_GREEDY && stats.obsolete > 0)) {
first_page = sector * COFFEE_PAGES_PER_SECTOR;
if(first_page < next_free) {
next_free = first_page;
}
if(isolation_count > 0) {
isolate_pages(first_page + COFFEE_PAGES_PER_SECTOR, isolation_count);
}
COFFEE_ERASE(sector);
PRINTF("Coffee: Erased sector %d!\n", sector);
if(mode == GC_RELUCTANT && isolation_count > 0) {
break;
}
}
}
}
/*---------------------------------------------------------------------------*/
static coffee_page_t
next_file(coffee_page_t page, struct file_header *hdr)
{
/*
* The quick-skip algorithm for finding file extents is the most
* essential part of Coffee. The file allocation rules enable this
* algorithm to quickly jump over free areas and allocated extents
* after reading single headers and determining their status.
*
* The worst-case performance occurs when we encounter multiple long
* sequences of isolated pages, but such sequences are uncommon and
* always shorter than a sector.
*/
if(HDR_FREE(*hdr)) {
return (page + COFFEE_PAGES_PER_SECTOR) & ~(COFFEE_PAGES_PER_SECTOR - 1);
} else if(HDR_ISOLATED(*hdr)) {
return page + 1;
}
return page + hdr->max_pages;
}
/*---------------------------------------------------------------------------*/
static struct file *
load_file(coffee_page_t start, struct file_header *hdr)
{
int i, unreferenced, free;
struct file *file;
/*
* We prefer to overwrite a free slot since unreferenced ones
* contain usable data. Free slots are designated by the page
* value INVALID_PAGE.
*/
for(i = 0, unreferenced = free = -1; i < COFFEE_MAX_OPEN_FILES; i++) {
if(FILE_FREE(&coffee_files[i])) {
free = i;
break;
} else if(FILE_UNREFERENCED(&coffee_files[i])) {
unreferenced = i;
}
}
if(free == -1) {
if(unreferenced != -1) {
i = unreferenced;
} else {
return NULL;
}
}
file = &coffee_files[i];
file->page = start;
file->end = UNKNOWN_OFFSET;
file->max_pages = hdr->max_pages;
file->flags = 0;
if(HDR_MODIFIED(*hdr)) {
file->flags |= COFFEE_FILE_MODIFIED;
}
/* We don't know the amount of records yet. */
file->record_count = -1;
return file;
}
/*---------------------------------------------------------------------------*/
static struct file *
find_file(const char *name)
{
int i;
struct file_header hdr;
coffee_page_t page;
/* First check if the file metadata is cached. */
for(i = 0; i < COFFEE_MAX_OPEN_FILES; i++) {
if(FILE_FREE(&coffee_files[i])) {
continue;
}
read_header(&hdr, coffee_files[i].page);
if(HDR_ACTIVE(hdr) && !HDR_LOG(hdr) && strcmp(name, hdr.name) == 0) {
return &coffee_files[i];
}
}
/* Scan the flash memory sequentially otherwise. */
for(page = 0; page < COFFEE_PAGE_COUNT; page = next_file(page, &hdr)) {
read_header(&hdr, page);
if(HDR_ACTIVE(hdr) && !HDR_LOG(hdr) && strcmp(name, hdr.name) == 0) {
return load_file(page, &hdr);
}
}
return NULL;
}
/*---------------------------------------------------------------------------*/
static cfs_offset_t
file_end(coffee_page_t start)
{
struct file_header hdr;
unsigned char buf[COFFEE_PAGE_SIZE];
coffee_page_t page;
int i;
read_header(&hdr, start);
/*
* Move from the end of the range towards the beginning and look for
* a byte that has been modified.
*
* An important implication of this is that if the last written bytes
* are zeroes, then these are skipped from the calculation.
*/
for(page = hdr.max_pages - 1; page >= 0; page--) {
COFFEE_READ(buf, sizeof(buf), (start + page) * COFFEE_PAGE_SIZE);
for(i = COFFEE_PAGE_SIZE - 1; i >= 0; i--) {
if(buf[i] != 0) {
if(page == 0 && i < sizeof(hdr)) {
return 0;
}
return 1 + i + (page * COFFEE_PAGE_SIZE) - sizeof(hdr);
}
}
}
/* All bytes are writable. */
return 0;
}
/*---------------------------------------------------------------------------*/
static coffee_page_t
find_contiguous_pages(coffee_page_t amount)
{
coffee_page_t page, start;
struct file_header hdr;
start = INVALID_PAGE;
for(page = next_free; page < COFFEE_PAGE_COUNT;) {
read_header(&hdr, page);
if(HDR_FREE(hdr)) {
if(start == INVALID_PAGE) {
start = page;
if(start + amount >= COFFEE_PAGE_COUNT) {
/* We can stop immediately if the remaining pages are not enough. */
break;
}
}
/* All remaining pages in this sector are free --
jump to the next sector. */
page = next_file(page, &hdr);
if(start + amount <= page) {
if(start == next_free) {
next_free = start + amount;
}
return start;
}
} else {
start = INVALID_PAGE;
page = next_file(page, &hdr);
}
}
return INVALID_PAGE;
}
/*---------------------------------------------------------------------------*/
static int
remove_by_page(coffee_page_t page, int remove_log, int close_fds,
int gc_allowed)
{
struct file_header hdr;
int i;
read_header(&hdr, page);
if(!HDR_ACTIVE(hdr)) {
return -1;
}
if(remove_log && HDR_MODIFIED(hdr)) {
if(remove_by_page(hdr.log_page, !REMOVE_LOG, !CLOSE_FDS, !ALLOW_GC) < 0) {
return -1;
}
}
hdr.flags |= HDR_FLAG_OBSOLETE;
write_header(&hdr, page);
gc_wait = 0;
/* Close all file descriptors that reference the removed file. */
if(close_fds) {
for(i = 0; i < COFFEE_FD_SET_SIZE; i++) {
if(coffee_fd_set[i].file != NULL && coffee_fd_set[i].file->page == page) {
coffee_fd_set[i].flags = COFFEE_FD_FREE;
}
}
}
for(i = 0; i < COFFEE_MAX_OPEN_FILES; i++) {
if(coffee_files[i].page == page) {
coffee_files[i].page = INVALID_PAGE;
coffee_files[i].references = 0;
coffee_files[i].max_pages = 0;
}
}
#if !COFFEE_EXTENDED_WEAR_LEVELLING
if(gc_allowed) {
collect_garbage(GC_RELUCTANT);
}
#endif
return 0;
}
/*---------------------------------------------------------------------------*/
static coffee_page_t
page_count(cfs_offset_t size)
{
return (size + sizeof(struct file_header) + COFFEE_PAGE_SIZE - 1) /
COFFEE_PAGE_SIZE;
}
/*---------------------------------------------------------------------------*/
static struct file *
reserve(const char *name, coffee_page_t pages,
int allow_duplicates, unsigned flags)
{
struct file_header hdr;
coffee_page_t page;
struct file *file;
if(!allow_duplicates && find_file(name) != NULL) {
return NULL;
}
page = find_contiguous_pages(pages);
if(page == INVALID_PAGE) {
if(gc_wait) {
return NULL;
}
collect_garbage(GC_GREEDY);
page = find_contiguous_pages(pages);
if(page == INVALID_PAGE) {
gc_wait = 1;
return NULL;
}
}
memset(&hdr, 0, sizeof(hdr));
strncpy(hdr.name, name, sizeof(hdr.name) - 1);
hdr.max_pages = pages;
hdr.flags = HDR_FLAG_ALLOCATED | flags;
write_header(&hdr, page);
PRINTF("Coffee: Reserved %u pages starting from %u for file %s\n",
(unsigned)pages, (unsigned)page, name);
file = load_file(page, &hdr);
if(file != NULL) {
file->end = 0;
}
return file;
}
/*---------------------------------------------------------------------------*/
#if COFFEE_MICRO_LOGS
static void
adjust_log_config(struct file_header *hdr,
uint16_t *log_record_size, uint16_t *log_records)
{
*log_record_size = hdr->log_record_size == 0 ?
COFFEE_PAGE_SIZE : hdr->log_record_size;
*log_records = hdr->log_records == 0 ?
COFFEE_LOG_SIZE / *log_record_size : hdr->log_records;
}
#endif /* COFFEE_MICRO_LOGS */
/*---------------------------------------------------------------------------*/
#if COFFEE_MICRO_LOGS
static uint16_t
modify_log_buffer(uint16_t log_record_size,
cfs_offset_t *offset, uint16_t *size)
{
uint16_t region;
region = *offset / log_record_size;
*offset %= log_record_size;
if(*size > log_record_size - *offset) {
*size = log_record_size - *offset;
}
return region;
}
#endif /* COFFEE_MICRO_LOGS */
/*---------------------------------------------------------------------------*/
#if COFFEE_MICRO_LOGS
static int
get_record_index(coffee_page_t log_page, uint16_t search_records,
uint16_t region)
{
cfs_offset_t base;
uint16_t processed;
uint16_t batch_size;
int16_t match_index, i;
base = absolute_offset(log_page, sizeof(uint16_t) * search_records);
batch_size = search_records > COFFEE_LOG_TABLE_LIMIT ?
COFFEE_LOG_TABLE_LIMIT : search_records;
processed = 0;
match_index = -1;
{
uint16_t indices[batch_size];
while(processed < search_records && match_index < 0) {
if(batch_size + processed > search_records) {
batch_size = search_records - processed;
}
base -= batch_size * sizeof(indices[0]);
COFFEE_READ(&indices, sizeof(indices[0]) * batch_size, base);
for(i = batch_size - 1; i >= 0; i--) {
if(indices[i] - 1 == region) {
match_index = search_records - processed - (batch_size - i);
break;
}
}
processed += batch_size;
}
}
return match_index;
}
#endif /* COFFEE_MICRO_LOGS */
/*---------------------------------------------------------------------------*/
#if COFFEE_MICRO_LOGS
static int
read_log_page(struct file_header *hdr, int16_t record_count,
struct log_param *lp)
{
uint16_t region;
int16_t match_index;
uint16_t log_record_size;
uint16_t log_records;
cfs_offset_t base;
uint16_t search_records;
adjust_log_config(hdr, &log_record_size, &log_records);
region = modify_log_buffer(log_record_size, &lp->offset, &lp->size);
search_records = record_count < 0 ? log_records : record_count;
match_index = get_record_index(hdr->log_page, search_records, region);
if(match_index < 0) {
return -1;
}
base = absolute_offset(hdr->log_page, log_records * sizeof(region));
base += (cfs_offset_t)match_index * log_record_size;
base += lp->offset;
COFFEE_READ(lp->buf, lp->size, base);
return lp->size;
}
#endif /* COFFEE_MICRO_LOGS */
/*---------------------------------------------------------------------------*/
#if COFFEE_MICRO_LOGS
static coffee_page_t
create_log(struct file *file, struct file_header *hdr)
{
uint16_t log_record_size, log_records;
cfs_offset_t size;
struct file *log_file;
adjust_log_config(hdr, &log_record_size, &log_records);
/* Log index size + log data size. */
size = log_records * (sizeof(uint16_t) + log_record_size);
log_file = reserve(hdr->name, page_count(size), 1, HDR_FLAG_LOG);
if(log_file == NULL) {
return INVALID_PAGE;
}
hdr->flags |= HDR_FLAG_MODIFIED;
hdr->log_page = log_file->page;
write_header(hdr, file->page);
file->flags |= COFFEE_FILE_MODIFIED;
return log_file->page;
}
#endif /* COFFEE_MICRO_LOGS */
/*---------------------------------------------------------------------------*/
static int
merge_log(coffee_page_t file_page, int extend)
{
struct file_header hdr, hdr2;
int fd, n;
cfs_offset_t offset;
coffee_page_t max_pages;
struct file *new_file;
int i;
read_header(&hdr, file_page);
fd = cfs_open(hdr.name, CFS_READ);
if(fd < 0) {
return -1;
}
/*
* The reservation function adds extra space for the header, which has
* already been accounted for in the previous reservation.
*/
max_pages = hdr.max_pages << extend;
new_file = reserve(hdr.name, max_pages, 1, 0);
if(new_file == NULL) {
cfs_close(fd);
return -1;
}
offset = 0;
do {
char buf[hdr.log_record_size == 0 ? COFFEE_PAGE_SIZE : hdr.log_record_size];
n = cfs_read(fd, buf, sizeof(buf));
if(n < 0) {
remove_by_page(new_file->page, !REMOVE_LOG, !CLOSE_FDS, ALLOW_GC);
cfs_close(fd);
return -1;
} else if(n > 0) {
COFFEE_WRITE(buf, n, absolute_offset(new_file->page, offset));
offset += n;
}
} while(n != 0);
for(i = 0; i < COFFEE_FD_SET_SIZE; i++) {
if(coffee_fd_set[i].flags != COFFEE_FD_FREE &&
coffee_fd_set[i].file->page == file_page) {
coffee_fd_set[i].file = new_file;
new_file->references++;
}
}
if(remove_by_page(file_page, REMOVE_LOG, !CLOSE_FDS, !ALLOW_GC) < 0) {
remove_by_page(new_file->page, !REMOVE_LOG, !CLOSE_FDS, !ALLOW_GC);
cfs_close(fd);
return -1;
}
/* Copy the log configuration. */
read_header(&hdr2, new_file->page);
hdr2.log_record_size = hdr.log_record_size;
hdr2.log_records = hdr.log_records;
write_header(&hdr2, new_file->page);
new_file->flags &= ~COFFEE_FILE_MODIFIED;
new_file->end = offset;
cfs_close(fd);
return 0;
}
/*---------------------------------------------------------------------------*/
#if COFFEE_MICRO_LOGS
static int
find_next_record(struct file *file, coffee_page_t log_page,
int log_records)
{
int log_record, preferred_batch_size;
if(file->record_count >= 0) {
return file->record_count;
}
preferred_batch_size = log_records > COFFEE_LOG_TABLE_LIMIT ?
COFFEE_LOG_TABLE_LIMIT : log_records;
{
/* The next log record is unknown at this point; search for it. */
uint16_t indices[preferred_batch_size];
uint16_t processed;
uint16_t batch_size;
log_record = log_records;
for(processed = 0; processed < log_records; processed += batch_size) {
batch_size = log_records - processed >= preferred_batch_size ?
preferred_batch_size : log_records - processed;
COFFEE_READ(&indices, batch_size * sizeof(indices[0]),
absolute_offset(log_page, processed * sizeof(indices[0])));
for(log_record = 0; log_record < batch_size; log_record++) {
if(indices[log_record] == 0) {
log_record += processed;
break;
}
}
}
}
return log_record;
}
#endif /* COFFEE_MICRO_LOGS */
/*---------------------------------------------------------------------------*/
#if COFFEE_MICRO_LOGS
static int
write_log_page(struct file *file, struct log_param *lp)
{
struct file_header hdr;
uint16_t region;
coffee_page_t log_page;
int16_t log_record;
uint16_t log_record_size;
uint16_t log_records;
cfs_offset_t offset;
struct log_param lp_out;
read_header(&hdr, file->page);
adjust_log_config(&hdr, &log_record_size, &log_records);
region = modify_log_buffer(log_record_size, &lp->offset, &lp->size);
log_page = 0;
if(HDR_MODIFIED(hdr)) {
/* A log structure has already been created. */
log_page = hdr.log_page;
log_record = find_next_record(file, log_page, log_records);
if(log_record >= log_records) {
/* The log is full; merge the log. */
PRINTF("Coffee: Merging the file %s with its log\n", hdr.name);
return merge_log(file->page, 0);
}
} else {
/* Create a log structure. */
log_page = create_log(file, &hdr);
if(log_page == INVALID_PAGE) {
return -1;
}
PRINTF("Coffee: Created a log structure for file %s at page %u\n",
hdr.name, (unsigned)log_page);
hdr.log_page = log_page;
log_record = 0;
}
{
char copy_buf[log_record_size];
lp_out.offset = offset = region * log_record_size;
lp_out.buf = copy_buf;
lp_out.size = log_record_size;
if((lp->offset > 0 || lp->size != log_record_size) &&
read_log_page(&hdr, log_record, &lp_out) < 0) {
COFFEE_READ(copy_buf, sizeof(copy_buf),
absolute_offset(file->page, offset));
}
memcpy(&copy_buf[lp->offset], lp->buf, lp->size);
/*
* Write the region number in the region index table.
* The region number is incremented to avoid values of zero.
*/
offset = absolute_offset(log_page, 0);
++region;
COFFEE_WRITE(&region, sizeof(region),
offset + log_record * sizeof(region));
offset += log_records * sizeof(region);
COFFEE_WRITE(copy_buf, sizeof(copy_buf),
offset + log_record * log_record_size);
file->record_count = log_record + 1;
}
return lp->size;
}
#endif /* COFFEE_MICRO_LOGS */
/*---------------------------------------------------------------------------*/
static int
get_available_fd(void)
{
int i;
for(i = 0; i < COFFEE_FD_SET_SIZE; i++) {
if(coffee_fd_set[i].flags == COFFEE_FD_FREE) {
return i;
}
}
return -1;
}
/*---------------------------------------------------------------------------*/
int
cfs_open(const char *name, int flags)
{
int fd;
struct file_desc *fdp;
fd = get_available_fd();
if(fd < 0) {
PRINTF("Coffee: Failed to allocate a new file descriptor!\n");
return -1;
}
fdp = &coffee_fd_set[fd];
fdp->flags = 0;
fdp->file = find_file(name);
if(fdp->file == NULL) {
if((flags & (CFS_READ | CFS_WRITE)) == CFS_READ) {
return -1;
}
fdp->file = reserve(name, page_count(COFFEE_DYN_SIZE), 1, 0);
if(fdp->file == NULL) {
return -1;
}
fdp->file->end = 0;
} else if(fdp->file->end == UNKNOWN_OFFSET) {
fdp->file->end = file_end(fdp->file->page);
}
fdp->flags |= flags;
fdp->offset = flags & CFS_APPEND ? fdp->file->end : 0;
fdp->file->references++;
return fd;
}
/*---------------------------------------------------------------------------*/
void
cfs_close(int fd)
{
if(FD_VALID(fd)) {
coffee_fd_set[fd].flags = COFFEE_FD_FREE;
coffee_fd_set[fd].file->references--;
coffee_fd_set[fd].file = NULL;
}
}
/*---------------------------------------------------------------------------*/
cfs_offset_t
cfs_seek(int fd, cfs_offset_t offset, int whence)
{
struct file_desc *fdp;
cfs_offset_t new_offset;
if(!FD_VALID(fd)) {
return -1;
}
fdp = &coffee_fd_set[fd];
if(whence == CFS_SEEK_SET) {
new_offset = offset;
} else if(whence == CFS_SEEK_END) {
new_offset = fdp->file->end + offset;
} else if(whence == CFS_SEEK_CUR) {
new_offset = fdp->offset + offset;
} else {
return (cfs_offset_t)-1;
}
if(new_offset < 0 || new_offset > fdp->file->max_pages * COFFEE_PAGE_SIZE) {
return -1;
}
if(fdp->file->end < new_offset) {
fdp->file->end = new_offset;
}
return fdp->offset = new_offset;
}
/*---------------------------------------------------------------------------*/
int
cfs_remove(const char *name)
{
struct file *file;
/*
* Coffee removes files by marking them as obsolete. The space
* is not guaranteed to be reclaimed immediately, but must be
* sweeped by the garbage collector. The garbage collector is
* called once a file reservation request cannot be granted.
*/
file = find_file(name);
if(file == NULL) {
return -1;
}
return remove_by_page(file->page, REMOVE_LOG, CLOSE_FDS, ALLOW_GC);
}
/*---------------------------------------------------------------------------*/
int
cfs_read(int fd, void *buf, unsigned size)
{
struct file_desc *fdp;
struct file *file;
#if COFFEE_MICRO_LOGS
struct file_header hdr;
struct log_param lp;
unsigned bytes_left;
int r;
#endif
if(!(FD_VALID(fd) && FD_READABLE(fd))) {
return -1;
}
fdp = &coffee_fd_set[fd];
file = fdp->file;
#if COFFEE_IO_SEMANTICS
if(fdp->io_flags & CFS_COFFEE_IO_ENSURE_READ_LENGTH) {
while(fdp->offset + size > file->end) {
((char*)buf)[--size] = 0;
}
} else {
#endif
if(fdp->offset + size > file->end) {
size = file->end - fdp->offset;
}
#if COFFEE_IO_SEMANTICS
}
#endif
/* If the file is not modified, read directly from the file extent. */
if(!FILE_MODIFIED(file)) {
COFFEE_READ(buf, size, absolute_offset(file->page, fdp->offset));
fdp->offset += size;
return size;
}
#if COFFEE_MICRO_LOGS
read_header(&hdr, file->page);
/*
* Copy the contents of the most recent log record. If there is
* no log record for the file area to read from, we simply read
* from the original file extent.
*/
for(bytes_left = size; bytes_left > 0; bytes_left -= r) {
lp.offset = fdp->offset;
lp.buf = buf;
lp.size = bytes_left;
r = read_log_page(&hdr, file->record_count, &lp);
/* Read from the original file if we cannot find the data in the log. */
if(r < 0) {
COFFEE_READ(buf, lp.size, absolute_offset(file->page, fdp->offset));
r = lp.size;
}
fdp->offset += r;
buf = (char *)buf + r;
}
#endif /* COFFEE_MICRO_LOGS */
return size;
}
/*---------------------------------------------------------------------------*/
int
cfs_write(int fd, const void *buf, unsigned size)
{
struct file_desc *fdp;
struct file *file;
#if COFFEE_MICRO_LOGS
int i;
struct log_param lp;
cfs_offset_t bytes_left;
int8_t need_dummy_write;
const char dummy[1] = { 0xff };
#endif
if(!(FD_VALID(fd) && FD_WRITABLE(fd))) {
return -1;
}
fdp = &coffee_fd_set[fd];
file = fdp->file;
/* Attempt to extend the file if we try to write past the end. */
#if COFFEE_IO_SEMANTICS
if(!(fdp->io_flags & CFS_COFFEE_IO_FIRM_SIZE)) {
#endif
while(size + fdp->offset + sizeof(struct file_header) >
(file->max_pages * COFFEE_PAGE_SIZE)) {
if(merge_log(file->page, 1) < 0) {
return -1;
}
file = fdp->file;
PRINTF("Extended the file at page %u\n", (unsigned)file->page);
}
#if COFFEE_IO_SEMANTICS
}
#endif
#if COFFEE_MICRO_LOGS
#if COFFEE_IO_SEMANTICS
if(!(fdp->io_flags & CFS_COFFEE_IO_FLASH_AWARE) &&
(FILE_MODIFIED(file) || fdp->offset < file->end)) {
#else
if(FILE_MODIFIED(file) || fdp->offset < file->end) {
#endif
need_dummy_write = 0;
for(bytes_left = size; bytes_left > 0;) {
lp.offset = fdp->offset;
lp.buf = buf;
lp.size = bytes_left;
i = write_log_page(file, &lp);
if(i < 0) {
/* Return -1 if we wrote nothing because the log write failed. */
if(size == bytes_left) {
return -1;
}
break;
} else if(i == 0) {
/* The file was merged with the log. */
file = fdp->file;
} else {
/* A log record was written. */
bytes_left -= i;
fdp->offset += i;
buf = (char *)buf + i;
/* Update the file end for a potential log merge that might
occur while writing log records. */
if(fdp->offset > file->end) {
file->end = fdp->offset;
need_dummy_write = 1;
}
}
}
if(need_dummy_write) {
/*
* A log record has been written at an offset beyond the original
* extent's end. Consequently, we need to write a dummy value at the
* corresponding end offset in the original extent to ensure that
* the correct file size is calculated when opening the file again.
*/
COFFEE_WRITE(dummy, 1, absolute_offset(file->page, fdp->offset - 1));
}
} else {
#endif /* COFFEE_MICRO_LOGS */
#if COFFEE_APPEND_ONLY
if(fdp->offset < file->end) {
return -1;
}
#endif /* COFFEE_APPEND_ONLY */
COFFEE_WRITE(buf, size, absolute_offset(file->page, fdp->offset));
fdp->offset += size;
#if COFFEE_MICRO_LOGS
}
#endif /* COFFEE_MICRO_LOGS */
if(fdp->offset > file->end) {
file->end = fdp->offset;
}
return size;
}
/*---------------------------------------------------------------------------*/
int
cfs_opendir(struct cfs_dir *dir, const char *name)
{
/*
* Coffee is only guaranteed to support the directory names "/" and ".",
* but it does not enforce this currently.
*/
memset(dir->dummy_space, 0, sizeof(coffee_page_t));
return 0;
}
/*---------------------------------------------------------------------------*/
int
cfs_readdir(struct cfs_dir *dir, struct cfs_dirent *record)
{
struct file_header hdr;
coffee_page_t page;
coffee_page_t next_page;
memcpy(&page, dir->dummy_space, sizeof(coffee_page_t));
while(page < COFFEE_PAGE_COUNT) {
read_header(&hdr, page);
if(HDR_ACTIVE(hdr) && !HDR_LOG(hdr)) {
memcpy(record->name, hdr.name, sizeof(record->name));
record->name[sizeof(record->name) - 1] = '\0';
record->size = file_end(page);
next_page = next_file(page, &hdr);
memcpy(dir->dummy_space, &next_page, sizeof(coffee_page_t));
return 0;
}
page = next_file(page, &hdr);
}
return -1;
}
/*---------------------------------------------------------------------------*/
void
cfs_closedir(struct cfs_dir *dir)
{
return;
}
/*---------------------------------------------------------------------------*/
int
cfs_coffee_reserve(const char *name, cfs_offset_t size)
{
return reserve(name, page_count(size), 0, 0) == NULL ? -1 : 0;
}
/*---------------------------------------------------------------------------*/
int
cfs_coffee_configure_log(const char *filename, unsigned log_size,
unsigned log_record_size)
{
struct file *file;
struct file_header hdr;
if(log_record_size == 0 || log_record_size > COFFEE_PAGE_SIZE ||
log_size < log_record_size) {
return -1;
}
file = find_file(filename);
if(file == NULL) {
return -1;
}
read_header(&hdr, file->page);
if(HDR_MODIFIED(hdr)) {
/* Too late to customize the log. */
return -1;
}
hdr.log_records = log_size / log_record_size;
hdr.log_record_size = log_record_size;
write_header(&hdr, file->page);
return 0;
}
/*---------------------------------------------------------------------------*/
#if COFFEE_IO_SEMANTICS
int
cfs_coffee_set_io_semantics(int fd, unsigned flags)
{
if(!FD_VALID(fd)) {
return -1;
}
coffee_fd_set[fd].io_flags |= flags;
return 0;
}
#endif
/*---------------------------------------------------------------------------*/
int
cfs_coffee_format(void)
{
coffee_page_t i;
PRINTF("Coffee: Formatting %u sectors", (unsigned)COFFEE_SECTOR_COUNT);
for(i = 0; i < COFFEE_SECTOR_COUNT; i++) {
COFFEE_ERASE(i);
PRINTF(".");
}
/* Formatting invalidates the file information. */
memset(&coffee_files, 0, sizeof(coffee_files));
memset(&coffee_fd_set, 0, sizeof(coffee_fd_set));
next_free = 0;
gc_wait = 1;
PRINTF(" done!\n");
return 0;
}
/*---------------------------------------------------------------------------*/
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