X-Git-Url: https://git.whamcloud.com/?a=blobdiff_plain;f=lib%2Fext2fs%2Funix_io.c;h=2ce05631f454612fa32a9695cb50348ecf5dfe4a;hb=fd1c5a0622a9578b86f695d2f60df7d4f8b21875;hp=0baae381ae1f8e74905ae9444e01afb120f5209c;hpb=4cbe8af4b0d0c72fb28bb500c1bd8a46b00fdde3;p=tools%2Fe2fsprogs.git

diff --git a/lib/ext2fs/unix_io.c b/lib/ext2fs/unix_io.c
index 0baae38..2ce0563 100644
--- a/lib/ext2fs/unix_io.c
+++ b/lib/ext2fs/unix_io.c
@@ -1,33 +1,67 @@
 /*
- * unix_io.c --- This is the Unix I/O interface to the I/O manager.
+ * unix_io.c --- This is the Unix (well, really POSIX) implementation
+ * 	of the I/O manager.
  *
  * Implements a one-block write-through cache.
  *
- * Copyright (C) 1993, 1994, 1995 Theodore Ts'o.
+ * 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.
+ * 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
+#ifndef _GNU_SOURCE
+#define _GNU_SOURCE
+#endif
+
+#include "config.h"
 #include <stdio.h>
 #include <string.h>
 #if HAVE_UNISTD_H
 #include <unistd.h>
 #endif
-#include <stdlib.h>
+#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>
-#if HAVE_ERRNO_H
-#include <errno.h>
+#endif
+#if HAVE_SYS_RESOURCE_H
+#include <sys/resource.h>
+#endif
+#if HAVE_LINUX_FALLOC_H
+#include <linux/falloc.h>
 #endif
 
-#include "et/com_err.h"
-#include "ext2fs/ext2_err.h"
-#include "io.h"
+#if defined(__linux__) && defined(_IO) && !defined(BLKROGET)
+#define BLKROGET   _IO(0x12, 94) /* Get read-only status (0 = read_write).  */
+#endif
+
+#undef ALIGN_DEBUG
+
+#include "ext2_fs.h"
+#include "ext2fs.h"
 
 /*
  * For checking structure magic numbers...
@@ -35,15 +69,34 @@
 
 #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;
-	char	*buf;
-	int	buf_block_nr;
+	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);
@@ -52,6 +105,20 @@ static errcode_t unix_read_blk(io_channel channel, unsigned long block,
 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 errcode_t unix_discard(io_channel channel, unsigned long long block,
+			      unsigned long long count);
 
 static struct struct_io_manager struct_unix_manager = {
 	EXT2_ET_MAGIC_IO_MANAGER,
@@ -61,36 +128,341 @@ static struct struct_io_manager struct_unix_manager = {
 	unix_set_blksize,
 	unix_read_blk,
 	unix_write_blk,
-	unix_flush
+	unix_flush,
+	unix_write_byte,
+	unix_set_option,
+	unix_get_stats,
+	unix_read_blk64,
+	unix_write_blk64,
+	unix_discard,
 };
 
 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 *bufv)
+{
+	errcode_t	retval;
+	ssize_t		size;
+	ext2_loff_t	location;
+	int		actual = 0;
+	unsigned char	*buf = bufv;
+
+	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 ((channel->align == 0) ||
+	    (IS_ALIGNED(buf, channel->align) &&
+	     IS_ALIGNED(size, channel->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 *bufv)
+{
+	ssize_t		size;
+	ext2_loff_t	location;
+	int		actual = 0;
+	errcode_t	retval;
+	const unsigned char *buf = bufv;
+
+	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 ((channel->align == 0) ||
+	    (IS_ALIGNED(buf, channel->align) &&
+	     IS_ALIGNED(size, channel->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 = io_channel_alloc_buf(channel, 0, &cache->buf);
+		if (retval)
+			return retval;
+	}
+	if (channel->align) {
+		if (data->bounce)
+			ext2fs_free_mem(&data->bounce);
+		retval = io_channel_alloc_buf(channel, 0, &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 */
+
+#ifdef __linux__
+#ifndef BLKDISCARDZEROES
+#define BLKDISCARDZEROES _IO(0x12,124)
+#endif
+#endif
+
 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, zeroes = 0;
+	int		f_nocache = 0;
+	ext2fs_struct_stat st;
+#ifdef __linux__
+	struct 		utsname ut;
+#endif
 
 	if (name == 0)
 		return EXT2_ET_BAD_DEVICE_NAME;
-	io = (io_channel) malloc(sizeof(struct struct_io_channel));
-	if (!io)
-		return ENOMEM;
+	retval = ext2fs_get_mem(sizeof(struct struct_io_channel), &io);
+	if (retval)
+		goto cleanup;
 	memset(io, 0, sizeof(struct struct_io_channel));
 	io->magic = EXT2_ET_MAGIC_IO_CHANNEL;
-	data = (struct unix_private_data *)
-		malloc(sizeof(struct unix_private_data));
-	if (!data) {
-		retval = ENOMEM;
+	retval = ext2fs_get_mem(sizeof(struct unix_private_data), &data);
+	if (retval)
 		goto cleanup;
-	}
+
 	io->manager = unix_io_manager;
-	io->name = malloc(strlen(name)+1);
-	if (!io->name) {
-		retval = ENOMEM;
+	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;
@@ -100,28 +472,128 @@ static errcode_t unix_open(const char *name, int flags, io_channel *channel)
 
 	memset(data, 0, sizeof(struct unix_private_data));
 	data->magic = EXT2_ET_MAGIC_UNIX_IO_CHANNEL;
-	data->buf = malloc(io->block_size);
-	data->buf_block_nr = -1;
-	if (!data->buf) {
-		retval = ENOMEM;
-		goto cleanup;
+	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 defined(O_DIRECT)
+	if (flags & IO_FLAG_DIRECT_IO) {
+		open_flags |= O_DIRECT;
+		io->align = ext2fs_get_dio_alignment(data->dev);
 	}
-	data->dev = open(name, (flags & IO_FLAG_RW) ? O_RDWR : O_RDONLY);
+#elif defined(F_NOCACHE)
+	if (flags & IO_FLAG_DIRECT_IO) {
+		f_nocache = F_NOCACHE;
+		io->align = 4096;
+	}
+#endif
+	data->flags = flags;
+
+	data->dev = ext2fs_open_file(io->name, open_flags, 0);
 	if (data->dev < 0) {
 		retval = errno;
 		goto cleanup;
 	}
+	if (f_nocache) {
+		if (fcntl(data->dev, f_nocache, 1) < 0) {
+			retval = errno;
+			goto cleanup;
+		}
+	}
+
+	/*
+	 * If the device is really a block device, then set the
+	 * appropriate flag, otherwise we can set DISCARD_ZEROES flag
+	 * because we are going to use punch hole instead of discard
+	 * and if it succeed, subsequent read from sparse area returns
+	 * zero.
+	 */
+	if (ext2fs_stat(io->name, &st) == 0) {
+		if (S_ISBLK(st.st_mode))
+			io->flags |= CHANNEL_FLAGS_BLOCK_DEVICE;
+		else
+			io->flags |= CHANNEL_FLAGS_DISCARD_ZEROES;
+	}
+
+#ifdef BLKDISCARDZEROES
+	ioctl(data->dev, BLKDISCARDZEROES, &zeroes);
+	if (zeroes)
+		io->flags |= CHANNEL_FLAGS_DISCARD_ZEROES;
+#endif
+
+#if defined(__CYGWIN__) || defined(__FreeBSD__) || defined(__FreeBSD_kernel__)
+	/*
+	 * Some operating systems require that the buffers be aligned,
+	 * regardless of O_DIRECT
+	 */
+	if (!io->align)
+		io->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')) &&
+	    (ext2fs_stat(io->name, &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 (io)
-		free(io);
 	if (data) {
-		if (data->buf)
-			free(data->buf);
-		free(data);
+		free_cache(data);
+		ext2fs_free_mem(&data);
 	}
+	if (io)
+		ext2fs_free_mem(&io);
 	return retval;
 }
 
@@ -136,148 +608,316 @@ static errcode_t unix_close(io_channel 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;
-	if (data->buf)
-		free(data->buf);
-	if (channel->private_data)
-		free(channel->private_data);
+	free_cache(data);
+
+	ext2fs_free_mem(&channel->private_data);
 	if (channel->name)
-		free(channel->name);
-	free(channel);
+		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(data->buf);
-		data->buf = malloc(blksize);
-		if (!data->buf)
-			return ENOMEM;
-		data->buf_block_nr = -1;
+		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,
+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;
-	size_t		size;
-	ext2_loff_t	location;
-	int		actual = 0;
+	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 it's in the cache, use it!
+	 * 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 == 1) && (block == data->buf_block_nr)) {
-		memcpy(buf, data->buf, channel->block_size);
-		return 0;
+	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);
 	}
-#if 0
-	printf("read_block %lu (%d)\n", block, count);
+
+	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
-	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_IO_LLSEEK_FAILED;
-		goto error_out;
+			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;
+		}
 	}
-	actual = read(data->dev, buf, size);
-	if (actual != size) {
-		if (actual < 0)
-			actual = 0;
-		retval = EXT2_ET_SHORT_READ;
-		goto error_out;
+	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);
 	}
-	if (count == 1) {
-		data->buf_block_nr = block;
-		memcpy(data->buf, buf, size);	/* Update the cache */
+
+	/*
+	 * 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 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;
+#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;
-	size_t		size;
-	ext2_loff_t	location;
-	int		actual = 0;
-	errcode_t	retval;
+	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 (count == 1)
-		size = channel->block_size;
-	else {
-		data->buf_block_nr = -1; 	/* Invalidate the cache */
-		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_IO_LLSEEK_FAILED;
-		goto error_out;
+	if (channel->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) {
-		retval = EXT2_ET_SHORT_WRITE;
-		goto error_out;
-	}
+	if (actual != size)
+		return EXT2_ET_SHORT_WRITE;
 
-	if ((count == 1) && (block == data->buf_block_nr))
-		memcpy(data->buf, buf, size); /* Update the cache */
-	
 	return 0;
-	
-error_out:
-	if (channel->write_error)
-		retval = (channel->write_error)(channel, block, count, buf,
-						size, actual, retval);
-	return retval;
 }
 
 /*
- * Flush data buffers to disk.  
+ * 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 0;
+	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;
 }
 
+#if defined(__linux__) && !defined(BLKDISCARD)
+#define BLKDISCARD		_IO(0x12,119)
+#endif
+
+static errcode_t unix_discard(io_channel channel, unsigned long long block,
+			      unsigned long long count)
+{
+	struct unix_private_data *data;
+	__uint64_t	range[2];
+	int		ret;
+
+	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->flags & CHANNEL_FLAGS_BLOCK_DEVICE) {
+#ifdef BLKDISCARD
+		range[0] = (__uint64_t)(block) * channel->block_size;
+		range[1] = (__uint64_t)(count) * channel->block_size;
+
+		ret = ioctl(data->dev, BLKDISCARD, &range);
+#else
+		goto unimplemented;
+#endif
+	} else {
+#if defined(HAVE_FALLOCATE) && defined(FALLOC_FL_PUNCH_HOLE)
+		/*
+		 * If we are not on block device, try to use punch hole
+		 * to reclaim free space.
+		 */
+		ret = fallocate(data->dev,
+				FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE,
+				(off_t)(block) * channel->block_size,
+				(off_t)(count) * channel->block_size);
+#else
+		goto unimplemented;
+#endif
+	}
+	if (ret < 0) {
+		if (errno == EOPNOTSUPP)
+			goto unimplemented;
+		return errno;
+	}
+	return 0;
+unimplemented:
+	return EXT2_ET_UNIMPLEMENTED;
+}