| /* |
| * 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 |
| |
| #if EXT2_FLAT_INCLUDES |
| #include "ext2_fs.h" |
| #else |
| #include <linux/ext2_fs.h> |
| #endif |
| |
| #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 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 |
| }; |
| |
| 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. |
| */ |
| struct unix_cache *find_cached_block(io_channel channel, |
| struct unix_private_data *data, |
| unsigned long block, |
| int get_cache) |
| { |
| struct unix_cache *cache, *free_cache, *oldest_cache; |
| int i; |
| |
| free_cache = oldest_cache = 0; |
| for (i=0, cache = data->cache; i < CACHE_SIZE; i++, cache++) { |
| if (!cache->in_use) { |
| free_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 (free_cache) |
| cache = free_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; |
| 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); |
| } |
| |
| 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(buf, cache->buf, channel->block_size); |
| count--; |
| block++; |
| buf += 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, buf))) |
| 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, buf, channel->block_size); |
| buf += 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; |
| char *cp; |
| int i, 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); |
| |
| 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, buf))) |
| retval = retval2; |
| } else { |
| memcpy(cache->buf, buf, channel->block_size); |
| cache->dirty = !writethrough; |
| } |
| count--; |
| block++; |
| buf += channel->block_size; |
| } |
| return retval; |
| } |
| |
| /* |
| * 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; |
| } |
| |