diff options
Diffstat (limited to 'e2fslib/unix_io.c')
| -rw-r--r-- | e2fslib/unix_io.c | 556 |
1 files changed, 0 insertions, 556 deletions
diff --git a/e2fslib/unix_io.c b/e2fslib/unix_io.c deleted file mode 100644 index 40bb6c2..0000000 --- a/e2fslib/unix_io.c +++ /dev/null @@ -1,556 +0,0 @@ -/* - * unix_io.c --- This is the Unix I/O interface to the I/O manager. - * - * Implements a one-block write-through cache. - * - * Copyright (C) 1993, 1994, 1995 Theodore Ts'o. - * - * %Begin-Header% - * This file may be redistributed under the terms of the GNU Public - * License. - * %End-Header% - */ - -#define _LARGEFILE_SOURCE -#define _LARGEFILE64_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> -#if HAVE_SYS_STAT_H -#include <sys/stat.h> -#endif -#if HAVE_SYS_TYPES_H -#include <sys/types.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; - int dirty:1; - int in_use:1; -}; - -#define CACHE_SIZE 8 -#define WRITE_VIA_CACHE_SIZE 4 /* Must be smaller than CACHE_SIZE */ - -struct unix_private_data { - int magic; - int dev; - int flags; - int access_time; - 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 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 -}; - -io_manager unix_io_manager = &struct_unix_manager; - -/* - * Here are the raw I/O functions - */ -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; - ext2_loff_t location; - int actual = 0; - - size = (count < 0) ? -count : count * channel->block_size; - location = (ext2_loff_t) block * channel->block_size; - 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; -} - -static errcode_t raw_write_blk(io_channel channel, - struct unix_private_data *data, - unsigned long block, - int count, const void *buf) -{ - size_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; - 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, - (void **) &cache->buf))) - return retval; - } - return 0; -} - -/* Free the cache buffers */ -static void free_cache(io_channel channel, - 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((void **) &cache->buf); - cache->buf = 0; - } -} - -/* - * Try to find a block in the cache. If get_cache is non-zero, then - * if the block isn't in the cache, evict the oldest block in the - * cache and create a new cache entry for the requested block. - */ -static struct unix_cache *find_cached_block(io_channel channel, - struct unix_private_data *data, - unsigned long block, - int get_cache) -{ - 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) { - 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 (!get_cache) - return 0; - - /* - * Try to allocate cache slot. - */ - if (unused_cache) - cache = unused_cache; - else { - cache = oldest_cache; - if (cache->dirty) - raw_write_blk(channel, data, - cache->block, 1, cache->buf); - } - cache->in_use = 1; - cache->block = block; - cache->access_time = ++data->access_time; - return cache; -} - -/* - * 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; -} - - - -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; - - if (name == 0) - return EXT2_ET_BAD_DEVICE_NAME; - retval = ext2fs_get_mem(sizeof(struct struct_io_channel), - (void **) &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), - (void **) &data); - if (retval) - goto cleanup; - - io->manager = unix_io_manager; - retval = ext2fs_get_mem(strlen(name)+1, (void **) &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 HAVE_OPEN64 - data->dev = open64(name, open_flags); -#else - data->dev = open(name, open_flags); -#endif - if (data->dev < 0) { - retval = errno; - goto cleanup; - } - *channel = io; - return 0; - -cleanup: - if (data) { - free_cache(io, data); - ext2fs_free_mem((void **) &data); - } - if (io) - ext2fs_free_mem((void **) &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; - - retval = flush_cached_blocks(channel, data, 0); - - if (close(data->dev) < 0) - retval = errno; - free_cache(channel, data); - if (channel->private_data) - ext2fs_free_mem((void **) &channel->private_data); - if (channel->name) - ext2fs_free_mem((void **) &channel->name); - ext2fs_free_mem((void **) &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) { - if ((retval = flush_cached_blocks(channel, data, 0))) - return retval; - - channel->block_size = blksize; - free_cache(channel, 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; - 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); - - /* - * If we're doing an odd-sized read, flush out the cache and - * then do a direct read. - */ - if (count < 0) { - 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(channel, data, block, 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(channel, data, block+i, 0)) - 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 = find_cached_block(channel, data, block++, 1); - if (cache) - memcpy(cache->buf, cp, channel->block_size); - cp += channel->block_size; - } - } - return 0; -} - -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; - errcode_t retval = 0, retval2; - 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); - - /* - * 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_VIA_CACHE_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(channel, data, block, 1); - if (!cache) { - /* - * Oh shit, we couldn't get cache descriptor. - * Force the write directly. - */ - if ((retval2 = raw_write_blk(channel, data, block, - 1, cp))) - retval = retval2; - } else { - memcpy(cache->buf, cp, channel->block_size); - cache->dirty = !writethrough; - } - count--; - block++; - cp += channel->block_size; - } - return retval; -} - -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; - size_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); - - /* - * Flush out the cache completely - */ - if ((retval = flush_cached_blocks(channel, data, 1))) - return retval; - - if (lseek(data->dev, 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); - - retval = flush_cached_blocks(channel, data, 0); - fsync(data->dev); - return retval; -} - |