/*
* unix_io.c --- This is the Unix (well, really POSIX) implementation
* of the I/O manager.
*
* Implements a one-block write-through cache.
*
* Includes support for Windows NT support under Cygwin.
*
* Copyright (C) 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001,
* 2002 by Theodore Ts'o.
*
* %Begin-Header%
* This file may be redistributed under the terms of the GNU Library
* General Public License, version 2.
* %End-Header%
*/
#define _LARGEFILE_SOURCE
#define _LARGEFILE64_SOURCE
#define _GNU_SOURCE
#include <stdio.h>
#include <string.h>
#if HAVE_UNISTD_H
#include <unistd.h>
#endif
#if HAVE_ERRNO_H
#include <errno.h>
#endif
#include <fcntl.h>
#include <time.h>
#ifdef __linux__
#include <sys/utsname.h>
#endif
#ifdef HAVE_SYS_IOCTL_H
#include <sys/ioctl.h>
#endif
#ifdef HAVE_SYS_MOUNT_H
#include <sys/mount.h>
#endif
#if HAVE_SYS_STAT_H
#include <sys/stat.h>
#endif
#if HAVE_SYS_TYPES_H
#include <sys/types.h>
#endif
#if HAVE_SYS_RESOURCE_H
#include <sys/resource.h>
#endif
#if defined(__linux__) && defined(_IO) && !defined(BLKROGET)
#define BLKROGET _IO(0x12, 94) /* Get read-only status (0 = read_write). */
#endif
#if defined(__linux__) && defined(_IO) && !defined(BLKSSZGET)
#define BLKSSZGET _IO(0x12,104)/* get block device sector size */
#endif
#undef ALIGN_DEBUG
#include "ext2_fs.h"
#include "ext2fs.h"
/*
* For checking structure magic numbers...
*/
#define EXT2_CHECK_MAGIC(struct, code) \
if ((struct)->magic != (code)) return (code)
struct unix_cache {
char *buf;
unsigned long block;
int access_time;
unsigned dirty:1;
unsigned in_use:1;
};
#define CACHE_SIZE 8
#define WRITE_DIRECT_SIZE 4 /* Must be smaller than CACHE_SIZE */
#define READ_DIRECT_SIZE 4 /* Should be smaller than CACHE_SIZE */
struct unix_private_data {
int magic;
int dev;
int flags;
int align;
int access_time;
ext2_loff_t offset;
struct unix_cache cache[CACHE_SIZE];
void *bounce;
struct struct_io_stats io_stats;
};
#define IS_ALIGNED(n, align) ((((unsigned long) n) & \
((unsigned long) ((align)-1))) == 0)
static errcode_t unix_open(const char *name, int flags, io_channel *channel);
static errcode_t unix_close(io_channel channel);
static errcode_t unix_set_blksize(io_channel channel, int blksize);
static errcode_t unix_read_blk(io_channel channel, unsigned long block,
int count, void *data);
static errcode_t unix_write_blk(io_channel channel, unsigned long block,
int count, const void *data);
static errcode_t unix_flush(io_channel channel);
static errcode_t unix_write_byte(io_channel channel, unsigned long offset,
int size, const void *data);
static errcode_t unix_set_option(io_channel channel, const char *option,
const char *arg);
static errcode_t unix_get_stats(io_channel channel, io_stats *stats)
;
static void reuse_cache(io_channel channel, struct unix_private_data *data,
struct unix_cache *cache, unsigned long long block);
static errcode_t unix_read_blk64(io_channel channel, unsigned long long block,
int count, void *data);
static errcode_t unix_write_blk64(io_channel channel, unsigned long long block,
int count, const void *data);
static struct struct_io_manager struct_unix_manager = {
EXT2_ET_MAGIC_IO_MANAGER,
"Unix I/O Manager",
unix_open,
unix_close,
unix_set_blksize,
unix_read_blk,
unix_write_blk,
unix_flush,
unix_write_byte,
unix_set_option,
unix_get_stats,
unix_read_blk64,
unix_write_blk64,
};
io_manager unix_io_manager = &struct_unix_manager;
static errcode_t unix_get_stats(io_channel channel, io_stats *stats)
{
errcode_t retval = 0;
struct unix_private_data *data;
EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
data = (struct unix_private_data *) channel->private_data;
EXT2_CHECK_MAGIC(data, EXT2_ET_MAGIC_UNIX_IO_CHANNEL);
if (stats)
*stats = &data->io_stats;
return retval;
}
/*
* Here are the raw I/O functions
*/
static errcode_t raw_read_blk(io_channel channel,
struct unix_private_data *data,
unsigned long long block,
int count, void *buf)
{
errcode_t retval;
ssize_t size;
ext2_loff_t location;
int actual = 0;
size = (count < 0) ? -count : count * channel->block_size;
data->io_stats.bytes_read += size;
location = ((ext2_loff_t) block * channel->block_size) + data->offset;
if (ext2fs_llseek(data->dev, location, SEEK_SET) != location) {
retval = errno ? errno : EXT2_ET_LLSEEK_FAILED;
goto error_out;
}
if ((data->align == 0) ||
((IS_ALIGNED(buf, data->align)) && IS_ALIGNED(size, data->align))) {
actual = read(data->dev, buf, size);
if (actual != size) {
short_read:
if (actual < 0)
actual = 0;
retval = EXT2_ET_SHORT_READ;
goto error_out;
}
return 0;
}
#ifdef ALIGN_DEBUG
printf("raw_read_blk: O_DIRECT fallback: %p %lu\n", buf,
(unsigned long) size);
#endif
/*
* The buffer or size which we're trying to read isn't aligned
* to the O_DIRECT rules, so we need to do this the hard way...
*/
while (size > 0) {
actual = read(data->dev, data->bounce, channel->block_size);
if (actual != channel->block_size)
goto short_read;
actual = size;
if (size > channel->block_size)
actual = channel->block_size;
memcpy(buf, data->bounce, actual);
size -= actual;
buf += actual;
}
return 0;
error_out:
memset((char *) buf+actual, 0, size-actual);
if (channel->read_error)
retval = (channel->read_error)(channel, block, count, buf,
size, actual, retval);
return retval;
}
static errcode_t raw_write_blk(io_channel channel,
struct unix_private_data *data,
unsigned long long block,
int count, const void *buf)
{
ssize_t size;
ext2_loff_t location;
int actual = 0;
errcode_t retval;
if (count == 1)
size = channel->block_size;
else {
if (count < 0)
size = -count;
else
size = count * channel->block_size;
}
data->io_stats.bytes_written += size;
location = ((ext2_loff_t) block * channel->block_size) + data->offset;
if (ext2fs_llseek(data->dev, location, SEEK_SET) != location) {
retval = errno ? errno : EXT2_ET_LLSEEK_FAILED;
goto error_out;
}
if ((data->align == 0) ||
((IS_ALIGNED(buf, data->align)) && IS_ALIGNED(size, data->align))) {
actual = write(data->dev, buf, size);
if (actual != size) {
short_write:
retval = EXT2_ET_SHORT_WRITE;
goto error_out;
}
return 0;
}
#ifdef ALIGN_DEBUG
printf("raw_write_blk: O_DIRECT fallback: %p %lu\n", buf,
(unsigned long) size);
#endif
/*
* The buffer or size which we're trying to write isn't aligned
* to the O_DIRECT rules, so we need to do this the hard way...
*/
while (size > 0) {
if (size < channel->block_size) {
actual = read(data->dev, data->bounce,
channel->block_size);
if (actual != channel->block_size) {
retval = EXT2_ET_SHORT_READ;
goto error_out;
}
}
actual = size;
if (size > channel->block_size)
actual = channel->block_size;
memcpy(data->bounce, buf, actual);
actual = write(data->dev, data->bounce, channel->block_size);
if (actual != channel->block_size)
goto short_write;
size -= actual;
buf += actual;
}
return 0;
error_out:
if (channel->write_error)
retval = (channel->write_error)(channel, block, count, buf,
size, actual, retval);
return retval;
}
/*
* Here we implement the cache functions
*/
/* Allocate the cache buffers */
static errcode_t alloc_cache(io_channel channel,
struct unix_private_data *data)
{
errcode_t retval;
struct unix_cache *cache;
int i;
data->access_time = 0;
for (i=0, cache = data->cache; i < CACHE_SIZE; i++, cache++) {
cache->block = 0;
cache->access_time = 0;
cache->dirty = 0;
cache->in_use = 0;
if (cache->buf)
ext2fs_free_mem(&cache->buf);
retval = ext2fs_get_memalign(channel->block_size,
data->align, &cache->buf);
if (retval)
return retval;
}
if (data->align) {
if (data->bounce)
ext2fs_free_mem(&data->bounce);
retval = ext2fs_get_memalign(channel->block_size, data->align,
&data->bounce);
}
return retval;
}
/* Free the cache buffers */
static void free_cache(struct unix_private_data *data)
{
struct unix_cache *cache;
int i;
data->access_time = 0;
for (i=0, cache = data->cache; i < CACHE_SIZE; i++, cache++) {
cache->block = 0;
cache->access_time = 0;
cache->dirty = 0;
cache->in_use = 0;
if (cache->buf)
ext2fs_free_mem(&cache->buf);
}
if (data->bounce)
ext2fs_free_mem(&data->bounce);
}
#ifndef NO_IO_CACHE
/*
* Try to find a block in the cache. If the block is not found, and
* eldest is a non-zero pointer, then fill in eldest with the cache
* entry to that should be reused.
*/
static struct unix_cache *find_cached_block(struct unix_private_data *data,
unsigned long long block,
struct unix_cache **eldest)
{
struct unix_cache *cache, *unused_cache, *oldest_cache;
int i;
unused_cache = oldest_cache = 0;
for (i=0, cache = data->cache; i < CACHE_SIZE; i++, cache++) {
if (!cache->in_use) {
if (!unused_cache)
unused_cache = cache;
continue;
}
if (cache->block == block) {
cache->access_time = ++data->access_time;
return cache;
}
if (!oldest_cache ||
(cache->access_time < oldest_cache->access_time))
oldest_cache = cache;
}
if (eldest)
*eldest = (unused_cache) ? unused_cache : oldest_cache;
return 0;
}
/*
* Reuse a particular cache entry for another block.
*/
static void reuse_cache(io_channel channel, struct unix_private_data *data,
struct unix_cache *cache, unsigned long long block)
{
if (cache->dirty && cache->in_use)
raw_write_blk(channel, data, cache->block, 1, cache->buf);
cache->in_use = 1;
cache->dirty = 0;
cache->block = block;
cache->access_time = ++data->access_time;
}
/*
* Flush all of the blocks in the cache
*/
static errcode_t flush_cached_blocks(io_channel channel,
struct unix_private_data *data,
int invalidate)
{
struct unix_cache *cache;
errcode_t retval, retval2;
int i;
retval2 = 0;
for (i=0, cache = data->cache; i < CACHE_SIZE; i++, cache++) {
if (!cache->in_use)
continue;
if (invalidate)
cache->in_use = 0;
if (!cache->dirty)
continue;
retval = raw_write_blk(channel, data,
cache->block, 1, cache->buf);
if (retval)
retval2 = retval;
else
cache->dirty = 0;
}
return retval2;
}
#endif /* NO_IO_CACHE */
static errcode_t unix_open(const char *name, int flags, io_channel *channel)
{
io_channel io = NULL;
struct unix_private_data *data = NULL;
errcode_t retval;
int open_flags;
int f_nocache = 0;
struct stat st;
#ifdef __linux__
struct utsname ut;
#endif
if (name == 0)
return EXT2_ET_BAD_DEVICE_NAME;
retval = ext2fs_get_mem(sizeof(struct struct_io_channel), &io);
if (retval)
return retval;
memset(io, 0, sizeof(struct struct_io_channel));
io->magic = EXT2_ET_MAGIC_IO_CHANNEL;
retval = ext2fs_get_mem(sizeof(struct unix_private_data), &data);
if (retval)
goto cleanup;
io->manager = unix_io_manager;
retval = ext2fs_get_mem(strlen(name)+1, &io->name);
if (retval)
goto cleanup;
strcpy(io->name, name);
io->private_data = data;
io->block_size = 1024;
io->read_error = 0;
io->write_error = 0;
io->refcount = 1;
memset(data, 0, sizeof(struct unix_private_data));
data->magic = EXT2_ET_MAGIC_UNIX_IO_CHANNEL;
data->io_stats.num_fields = 2;
open_flags = (flags & IO_FLAG_RW) ? O_RDWR : O_RDONLY;
if (flags & IO_FLAG_EXCLUSIVE)
open_flags |= O_EXCL;
if (flags & IO_FLAG_DIRECT_IO)
#if !defined(O_DIRECT) && defined(F_NOCACHE)
f_nocache = F_NOCACHE;
#else
open_flags |= O_DIRECT;
#endif
data->flags = flags;
#ifdef HAVE_OPEN64
data->dev = open64(io->name, open_flags);
#else
data->dev = open(io->name, open_flags);
#endif
if (data->dev < 0) {
retval = errno;
goto cleanup;
}
if (f_nocache) {
if (fcntl(data->dev, f_nocache, 1) < 0) {
retval = errno;
goto cleanup;
}
}
#ifdef BLKSSZGET
if (flags & IO_FLAG_DIRECT_IO) {
if (ioctl(data->dev, BLKSSZGET, &data->align) != 0)
data->align = io->block_size;
}
#endif
#if defined(__CYGWIN__) || defined(__FreeBSD__) || defined(__FreeBSD_kernel__)
/*
* Some operating systems require that the buffers be aligned,
* regardless of O_DIRECT
*/
data->align = 512;
#endif
if ((retval = alloc_cache(io, data)))
goto cleanup;
#ifdef BLKROGET
if (flags & IO_FLAG_RW) {
int error;
int readonly = 0;
/* Is the block device actually writable? */
error = ioctl(data->dev, BLKROGET, &readonly);
if (!error && readonly) {
close(data->dev);
retval = EPERM;
goto cleanup;
}
}
#endif
#ifdef __linux__
#undef RLIM_INFINITY
#if (defined(__alpha__) || ((defined(__sparc__) || defined(__mips__)) && (SIZEOF_LONG == 4)))
#define RLIM_INFINITY ((unsigned long)(~0UL>>1))
#else
#define RLIM_INFINITY (~0UL)
#endif
/*
* Work around a bug in 2.4.10-2.4.18 kernels where writes to
* block devices are wrongly getting hit by the filesize
* limit. This workaround isn't perfect, since it won't work
* if glibc wasn't built against 2.2 header files. (Sigh.)
*
*/
if ((flags & IO_FLAG_RW) &&
(uname(&ut) == 0) &&
((ut.release[0] == '2') && (ut.release[1] == '.') &&
(ut.release[2] == '4') && (ut.release[3] == '.') &&
(ut.release[4] == '1') && (ut.release[5] >= '0') &&
(ut.release[5] < '8')) &&
(fstat(data->dev, &st) == 0) &&
(S_ISBLK(st.st_mode))) {
struct rlimit rlim;
rlim.rlim_cur = rlim.rlim_max = (unsigned long) RLIM_INFINITY;
setrlimit(RLIMIT_FSIZE, &rlim);
getrlimit(RLIMIT_FSIZE, &rlim);
if (((unsigned long) rlim.rlim_cur) <
((unsigned long) rlim.rlim_max)) {
rlim.rlim_cur = rlim.rlim_max;
setrlimit(RLIMIT_FSIZE, &rlim);
}
}
#endif
*channel = io;
return 0;
cleanup:
if (data) {
free_cache(data);
ext2fs_free_mem(&data);
}
if (io)
ext2fs_free_mem(&io);
return retval;
}
static errcode_t unix_close(io_channel channel)
{
struct unix_private_data *data;
errcode_t retval = 0;
EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
data = (struct unix_private_data *) channel->private_data;
EXT2_CHECK_MAGIC(data, EXT2_ET_MAGIC_UNIX_IO_CHANNEL);
if (--channel->refcount > 0)
return 0;
#ifndef NO_IO_CACHE
retval = flush_cached_blocks(channel, data, 0);
#endif
if (close(data->dev) < 0)
retval = errno;
free_cache(data);
ext2fs_free_mem(&channel->private_data);
if (channel->name)
ext2fs_free_mem(&channel->name);
ext2fs_free_mem(&channel);
return retval;
}
static errcode_t unix_set_blksize(io_channel channel, int blksize)
{
struct unix_private_data *data;
errcode_t retval;
EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
data = (struct unix_private_data *) channel->private_data;
EXT2_CHECK_MAGIC(data, EXT2_ET_MAGIC_UNIX_IO_CHANNEL);
if (channel->block_size != blksize) {
#ifndef NO_IO_CACHE
if ((retval = flush_cached_blocks(channel, data, 0)))
return retval;
#endif
channel->block_size = blksize;
free_cache(data);
if ((retval = alloc_cache(channel, data)))
return retval;
}
return 0;
}
static errcode_t unix_read_blk64(io_channel channel, unsigned long long block,
int count, void *buf)
{
struct unix_private_data *data;
struct unix_cache *cache, *reuse[READ_DIRECT_SIZE];
errcode_t retval;
char *cp;
int i, j;
EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
data = (struct unix_private_data *) channel->private_data;
EXT2_CHECK_MAGIC(data, EXT2_ET_MAGIC_UNIX_IO_CHANNEL);
#ifdef NO_IO_CACHE
return raw_read_blk(channel, data, block, count, buf);
#else
/*
* If we're doing an odd-sized read or a very large read,
* flush out the cache and then do a direct read.
*/
if (count < 0 || count > WRITE_DIRECT_SIZE) {
if ((retval = flush_cached_blocks(channel, data, 0)))
return retval;
return raw_read_blk(channel, data, block, count, buf);
}
cp = buf;
while (count > 0) {
/* If it's in the cache, use it! */
if ((cache = find_cached_block(data, block, &reuse[0]))) {
#ifdef DEBUG
printf("Using cached block %lu\n", block);
#endif
memcpy(cp, cache->buf, channel->block_size);
count--;
block++;
cp += channel->block_size;
continue;
}
if (count == 1) {
/*
* Special case where we read directly into the
* cache buffer; important in the O_DIRECT case
*/
cache = reuse[0];
reuse_cache(channel, data, cache, block);
if ((retval = raw_read_blk(channel, data, block, 1,
cache->buf))) {
cache->in_use = 0;
return retval;
}
memcpy(cp, cache->buf, channel->block_size);
return 0;
}
/*
* Find the number of uncached blocks so we can do a
* single read request
*/
for (i=1; i < count; i++)
if (find_cached_block(data, block+i, &reuse[i]))
break;
#ifdef DEBUG
printf("Reading %d blocks starting at %lu\n", i, block);
#endif
if ((retval = raw_read_blk(channel, data, block, i, cp)))
return retval;
/* Save the results in the cache */
for (j=0; j < i; j++) {
count--;
cache = reuse[j];
reuse_cache(channel, data, cache, block++);
memcpy(cache->buf, cp, channel->block_size);
cp += channel->block_size;
}
}
return 0;
#endif /* NO_IO_CACHE */
}
static errcode_t unix_read_blk(io_channel channel, unsigned long block,
int count, void *buf)
{
return unix_read_blk64(channel, block, count, buf);
}
static errcode_t unix_write_blk64(io_channel channel, unsigned long long block,
int count, const void *buf)
{
struct unix_private_data *data;
struct unix_cache *cache, *reuse;
errcode_t retval = 0;
const char *cp;
int writethrough;
EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
data = (struct unix_private_data *) channel->private_data;
EXT2_CHECK_MAGIC(data, EXT2_ET_MAGIC_UNIX_IO_CHANNEL);
#ifdef NO_IO_CACHE
return raw_write_blk(channel, data, block, count, buf);
#else
/*
* If we're doing an odd-sized write or a very large write,
* flush out the cache completely and then do a direct write.
*/
if (count < 0 || count > WRITE_DIRECT_SIZE) {
if ((retval = flush_cached_blocks(channel, data, 1)))
return retval;
return raw_write_blk(channel, data, block, count, buf);
}
/*
* For a moderate-sized multi-block write, first force a write
* if we're in write-through cache mode, and then fill the
* cache with the blocks.
*/
writethrough = channel->flags & CHANNEL_FLAGS_WRITETHROUGH;
if (writethrough)
retval = raw_write_blk(channel, data, block, count, buf);
cp = buf;
while (count > 0) {
cache = find_cached_block(data, block, &reuse);
if (!cache) {
cache = reuse;
reuse_cache(channel, data, cache, block);
}
memcpy(cache->buf, cp, channel->block_size);
cache->dirty = !writethrough;
count--;
block++;
cp += channel->block_size;
}
return retval;
#endif /* NO_IO_CACHE */
}
static errcode_t unix_write_blk(io_channel channel, unsigned long block,
int count, const void *buf)
{
return unix_write_blk64(channel, block, count, buf);
}
static errcode_t unix_write_byte(io_channel channel, unsigned long offset,
int size, const void *buf)
{
struct unix_private_data *data;
errcode_t retval = 0;
ssize_t actual;
EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
data = (struct unix_private_data *) channel->private_data;
EXT2_CHECK_MAGIC(data, EXT2_ET_MAGIC_UNIX_IO_CHANNEL);
if (data->align != 0) {
#ifdef ALIGN_DEBUG
printf("unix_write_byte: O_DIRECT fallback\n");
#endif
return EXT2_ET_UNIMPLEMENTED;
}
#ifndef NO_IO_CACHE
/*
* Flush out the cache completely
*/
if ((retval = flush_cached_blocks(channel, data, 1)))
return retval;
#endif
if (lseek(data->dev, offset + data->offset, SEEK_SET) < 0)
return errno;
actual = write(data->dev, buf, size);
if (actual != size)
return EXT2_ET_SHORT_WRITE;
return 0;
}
/*
* Flush data buffers to disk.
*/
static errcode_t unix_flush(io_channel channel)
{
struct unix_private_data *data;
errcode_t retval = 0;
EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
data = (struct unix_private_data *) channel->private_data;
EXT2_CHECK_MAGIC(data, EXT2_ET_MAGIC_UNIX_IO_CHANNEL);
#ifndef NO_IO_CACHE
retval = flush_cached_blocks(channel, data, 0);
#endif
fsync(data->dev);
return retval;
}
static errcode_t unix_set_option(io_channel channel, const char *option,
const char *arg)
{
struct unix_private_data *data;
unsigned long long tmp;
char *end;
EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
data = (struct unix_private_data *) channel->private_data;
EXT2_CHECK_MAGIC(data, EXT2_ET_MAGIC_UNIX_IO_CHANNEL);
if (!strcmp(option, "offset")) {
if (!arg)
return EXT2_ET_INVALID_ARGUMENT;
tmp = strtoull(arg, &end, 0);
if (*end)
return EXT2_ET_INVALID_ARGUMENT;
data->offset = tmp;
if (data->offset < 0)
return EXT2_ET_INVALID_ARGUMENT;
return 0;
}
return EXT2_ET_INVALID_ARGUMENT;
}