diff options
Diffstat (limited to 'e2fsprogs/ext2fs/unix_io.c')
| -rw-r--r-- | e2fsprogs/ext2fs/unix_io.c | 707 |
1 files changed, 707 insertions, 0 deletions
diff --git a/e2fsprogs/ext2fs/unix_io.c b/e2fsprogs/ext2fs/unix_io.c new file mode 100644 index 000000000..5bc7a6abe --- /dev/null +++ b/e2fsprogs/ext2fs/unix_io.c @@ -0,0 +1,707 @@ +/* + * 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 Public + * License. + * %End-Header% + */ + +#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 +#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 + +#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 access_time; + ext2_loff_t offset; + struct unix_cache cache[CACHE_SIZE]; +}; + +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 void reuse_cache(io_channel channel, struct unix_private_data *data, + struct unix_cache *cache, unsigned long block); + +/* __FreeBSD_kernel__ is defined by GNU/kFreeBSD - the FreeBSD kernel + * does not know buffered block devices - everything is raw. */ +#if defined(__CYGWIN__) || defined(__FreeBSD__) || defined(__FreeBSD_kernel__) +#define NEED_BOUNCE_BUFFER +#else +#undef NEED_BOUNCE_BUFFER +#endif + +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, +#ifdef NEED_BOUNCE_BUFFER + 0, +#else + unix_write_byte, +#endif + unix_set_option +}; + +io_manager unix_io_manager = &struct_unix_manager; + +/* + * Here are the raw I/O functions + */ +#ifndef NEED_BOUNCE_BUFFER +static errcode_t raw_read_blk(io_channel channel, + struct unix_private_data *data, + unsigned 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; + 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; + } + actual = read(data->dev, buf, size); + if (actual != size) { + if (actual < 0) + actual = 0; + retval = EXT2_ET_SHORT_READ; + goto error_out; + } + 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; +} +#else /* NEED_BOUNCE_BUFFER */ +/* + * Windows and FreeBSD block devices only allow sector alignment IO in offset and size + */ +static errcode_t raw_read_blk(io_channel channel, + struct unix_private_data *data, + unsigned long block, + int count, void *buf) +{ + errcode_t retval; + size_t size, alignsize, fragment; + ext2_loff_t location; + int total = 0, actual; +#define BLOCKALIGN 512 + char sector[BLOCKALIGN]; + + size = (count < 0) ? -count : count * channel->block_size; + location = ((ext2_loff_t) block * channel->block_size) + data->offset; +#ifdef DEBUG + printf("count=%d, size=%d, block=%d, blk_size=%d, location=%lx\n", + count, size, block, channel->block_size, location); +#endif + if (ext2fs_llseek(data->dev, location, SEEK_SET) != location) { + retval = errno ? errno : EXT2_ET_LLSEEK_FAILED; + goto error_out; + } + fragment = size % BLOCKALIGN; + alignsize = size - fragment; + if (alignsize) { + actual = read(data->dev, buf, alignsize); + if (actual != alignsize) + goto short_read; + } + if (fragment) { + actual = read(data->dev, sector, BLOCKALIGN); + if (actual != BLOCKALIGN) + goto short_read; + memcpy(buf+alignsize, sector, fragment); + } + return 0; + +short_read: + if (actual>0) + total += actual; + retval = EXT2_ET_SHORT_READ; + +error_out: + memset((char *) buf+total, 0, size-actual); + if (channel->read_error) + retval = (channel->read_error)(channel, block, count, buf, + size, actual, retval); + return retval; +} +#endif + +static errcode_t raw_write_blk(io_channel channel, + struct unix_private_data *data, + unsigned 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; + } + + 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; + } + + actual = write(data->dev, buf, size); + if (actual != size) { + retval = EXT2_ET_SHORT_WRITE; + goto error_out; + } + 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 ((retval = ext2fs_get_mem(channel->block_size, + &cache->buf))) + return retval; + } + return 0; +} + +/* 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); + cache->buf = 0; + } +} + +#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 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 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; + 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; + + if ((retval = alloc_cache(io, data))) + goto cleanup; + + open_flags = (flags & IO_FLAG_RW) ? O_RDWR : O_RDONLY; +#ifdef CONFIG_LFS + data->dev = open64(io->name, open_flags); +#else + data->dev = open(io->name, open_flags); +#endif + if (data->dev < 0) { + retval = errno; + goto cleanup; + } + +#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_blk(io_channel channel, unsigned 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 %d\n", block); +#endif + memcpy(cp, cache->buf, channel->block_size); + count--; + block++; + cp += channel->block_size; + continue; + } + /* + * 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 %d\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_write_blk(io_channel channel, unsigned 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_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); + +#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 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 = strtoul(arg, &end, 0); + if (*end) + return EXT2_ET_INVALID_ARGUMENT; + data->offset = tmp; + return 0; + } + return EXT2_ET_INVALID_ARGUMENT; +} |