Date:	Wed, 6 Feb 2013 15:02:03 +0000
From:	James Hogan <james.hogan@...tec.com>
To:	James Hogan <james.hogan@...tec.com>
CC:	<linux-kernel@...r.kernel.org>, <linux-arch@...r.kernel.org>,
	"Arnd Bergmann" <arnd@...db.de>,
	Alexander Viro <viro@...iv.linux.org.uk>,
	"Andrew Morton" <akpm@...ux-foundation.org>,
	Mauro Carvalho Chehab <mchehab@...hat.com>,
	Cesar Eduardo Barros <cesarb@...arb.net>,
	Joe Perches <joe@...ches.com>,
	"David S. Miller" <davem@...emloft.net>,
	<linux-fsdevel@...r.kernel.org>
Subject: Re: [PATCH v4 43/43] fs: imgdafs: Add IMG DAFS filesystem for metag

Ping.

Any chance of an Ack from somebody on this patch? I'm currently holding
off including it in the arch/metag tree.

Thanks
James

On 29/01/13 14:15, James Hogan wrote:
> Add the IMG Debug Adapter File System (DAFS) for metag, which uses
> SWITCH operations to communicate with a file server on a host computer
> via a JTAG debug adapter.
> 
> Signed-off-by: James Hogan <james.hogan@...tec.com>
> Cc: Alexander Viro <viro@...iv.linux.org.uk>
> Cc: Andrew Morton <akpm@...ux-foundation.org>
> Cc: Mauro Carvalho Chehab <mchehab@...hat.com>
> Cc: Cesar Eduardo Barros <cesarb@...arb.net>
> Cc: Joe Perches <joe@...ches.com>
> Cc: "David S. Miller" <davem@...emloft.net>
> Cc: linux-fsdevel@...r.kernel.org
> ---
> v4:
>   * clean up fscall similarly to chancall in tty/metag_da
> 
> v2:
>   * fixed fserrno problem (Al Viro)
>   * renamed to imgdafs
> 
>  MAINTAINERS          |    1 +
>  arch/metag/Kconfig   |    1 +
>  fs/Kconfig           |    1 +
>  fs/Makefile          |    1 +
>  fs/imgdafs/Kconfig   |    6 +
>  fs/imgdafs/Makefile  |    7 +
>  fs/imgdafs/imgdafs.h |   80 +++++
>  fs/imgdafs/inode.c   |  843 ++++++++++++++++++++++++++++++++++++++++++++++++++
>  8 files changed, 940 insertions(+), 0 deletions(-)
>  create mode 100644 fs/imgdafs/Kconfig
>  create mode 100644 fs/imgdafs/Makefile
>  create mode 100644 fs/imgdafs/imgdafs.h
>  create mode 100644 fs/imgdafs/inode.c
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index cb89fe3..6b02aea 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -5044,6 +5044,7 @@ F:	drivers/clocksource/metag_generic.c
>  F:	drivers/irqchip/irq-metag.c
>  F:	drivers/irqchip/irq-metag-ext.c
>  F:	drivers/tty/metag_da.c
> +F:	fs/imgdafs/
>  
>  MICROBLAZE ARCHITECTURE
>  M:	Michal Simek <monstr@...str.eu>
> diff --git a/arch/metag/Kconfig b/arch/metag/Kconfig
> index 9cba2f9..30adc78 100644
> --- a/arch/metag/Kconfig
> +++ b/arch/metag/Kconfig
> @@ -224,6 +224,7 @@ config METAG_DA
>  	  This enables support for services provided by DA JTAG debug adapters,
>  	  such as:
>  	  - communication over DA channels (such as the console driver).
> +	  - use of the DA filesystem.
>  
>  menu "Boot options"
>  
> diff --git a/fs/Kconfig b/fs/Kconfig
> index 780725a..6deefc1 100644
> --- a/fs/Kconfig
> +++ b/fs/Kconfig
> @@ -211,6 +211,7 @@ source "fs/sysv/Kconfig"
>  source "fs/ufs/Kconfig"
>  source "fs/exofs/Kconfig"
>  source "fs/f2fs/Kconfig"
> +source "fs/imgdafs/Kconfig"
>  
>  endif # MISC_FILESYSTEMS
>  
> diff --git a/fs/Makefile b/fs/Makefile
> index 9d53192..b070fca 100644
> --- a/fs/Makefile
> +++ b/fs/Makefile
> @@ -127,3 +127,4 @@ obj-$(CONFIG_F2FS_FS)		+= f2fs/
>  obj-y				+= exofs/ # Multiple modules
>  obj-$(CONFIG_CEPH_FS)		+= ceph/
>  obj-$(CONFIG_PSTORE)		+= pstore/
> +obj-$(CONFIG_IMGDAFS_FS)	+= imgdafs/
> diff --git a/fs/imgdafs/Kconfig b/fs/imgdafs/Kconfig
> new file mode 100644
> index 0000000..5293adb
> --- /dev/null
> +++ b/fs/imgdafs/Kconfig
> @@ -0,0 +1,6 @@
> +config IMGDAFS_FS
> +	bool "Meta DA filesystem support"
> +	depends on METAG_DA
> +	help
> +	  This enables the DA filesystem, which allows Linux to
> +	  to access files on a system attached via a debug adapter.
> diff --git a/fs/imgdafs/Makefile b/fs/imgdafs/Makefile
> new file mode 100644
> index 0000000..169a3c6
> --- /dev/null
> +++ b/fs/imgdafs/Makefile
> @@ -0,0 +1,7 @@
> +#
> +# Makefile for DAfs the Debug Adapter filesystem.
> +#
> +
> +obj-$(CONFIG_IMGDAFS_FS) += imgdafs.o
> +
> +imgdafs-objs := inode.o
> diff --git a/fs/imgdafs/imgdafs.h b/fs/imgdafs/imgdafs.h
> new file mode 100644
> index 0000000..6c1da13
> --- /dev/null
> +++ b/fs/imgdafs/imgdafs.h
> @@ -0,0 +1,80 @@
> +#ifndef _IMGDAFS_H_
> +#define _IMGDAFS_H_
> +
> +#define DA_OP_OPEN 0
> +#define DA_OP_CREAT 1
> +#define DA_OP_READ 2
> +#define DA_OP_WRITE 3
> +#define DA_OP_CLOSE 4
> +#define DA_OP_LINK 5
> +#define DA_OP_LSEEK 6
> +#define DA_OP_UNLINK 7
> +#define DA_OP_ISATTY 8
> +#define DA_OP_FCNTL 9
> +#define DA_OP_STAT 10
> +#define DA_OP_FSTAT 11
> +#define DA_OP_GETCWD 12
> +#define DA_OP_CHDIR 13
> +#define DA_OP_MKDIR 14
> +#define DA_OP_RMDIR 15
> +#define DA_OP_FINDFIRST 16
> +#define DA_OP_FINDNEXT 17
> +#define DA_OP_FINDCLOSE 18
> +#define DA_OP_CHMOD 19
> +#define DA_OP_PREAD 20
> +#define DA_OP_PWRITE 21
> +
> +#define OS_TYPE_FILE 1
> +#define OS_TYPE_DIR 2
> +#define OS_TYPE_SYMLINK 3
> +#define OS_TYPE_CHARDEV 4
> +#define OS_TYPE_BLOCKDEV 5
> +#define OS_TYPE_FIFO 6
> +#define OS_TYPE_SOCK 7
> +
> +#define DA_O_RDONLY 0
> +#define DA_O_WRONLY 1
> +#define DA_O_RDWR 2
> +#define DA_O_APPEND 8
> +#define DA_O_CREAT 0x0200
> +#define DA_O_TRUNC 0x0400
> +#define DA_O_EXCL 0x0800
> +
> +#define DA_O_AFFINITY_THREAD_0 0x10000
> +#define DA_O_AFFINITY_THREAD_1 0x20000
> +#define DA_O_AFFINITY_THREAD_2 0x40000
> +#define DA_O_AFFINITY_THREAD_3 0x80000
> +#define DA_O_AFFINITY_SHIFT 16
> +
> +#define DA_S_IWUSR	0200	/* 0x80 */
> +#define DA_S_IRUSR	0400	/* 0x100 */
> +
> +struct da_stat {
> +	short st_dev;
> +	unsigned short st_ino;
> +	unsigned st_mode;
> +	unsigned short st_nlink;
> +	unsigned short st_uid;
> +	unsigned short st_gid;
> +	short st_rdev;
> +	int st_size;
> +	int st_atime;
> +	int st_spare1;
> +	int st_mtime;
> +	int st_spare2;
> +	int st_ctime;
> +	int st_spare3;
> +	int st_blksize;
> +	int st_blocks;
> +	int st_spare4[2];
> +};
> +
> +#define _A_SUBDIR 0x10
> +
> +struct da_finddata {
> +	unsigned long size;
> +	unsigned long attrib;
> +	char name[260];
> +};
> +
> +#endif
> diff --git a/fs/imgdafs/inode.c b/fs/imgdafs/inode.c
> new file mode 100644
> index 0000000..5808d90
> --- /dev/null
> +++ b/fs/imgdafs/inode.c
> @@ -0,0 +1,843 @@
> +/*
> + * Copyright (C) 2008,2009,2010 Imagination Technologies Ltd.
> + * Licensed under the GPL
> + *
> + * Based on hostfs for UML.
> + *
> + */
> +
> +#include <linux/fs.h>
> +#include <linux/module.h>
> +#include <linux/mm.h>
> +#include <linux/pagemap.h>
> +#include <linux/seq_file.h>
> +#include <linux/mount.h>
> +#include <linux/slab.h>
> +
> +#include <asm/da.h>
> +#include <asm/hwthread.h>
> +
> +#include "imgdafs.h"
> +
> +static int fscall(int in_system_call, int in_arg1, int in_arg2, int in_arg3,
> +		  int in_arg4, int in_arg5, int *fserrno)
> +{
> +	register int arg1            asm("D1Ar1") = in_arg1;
> +	register int arg2            asm("D0Ar2") = in_arg2;
> +	register int arg3            asm("D1Ar3") = in_arg3;
> +	register int arg4            asm("D0Ar4") = in_arg4;
> +	register int arg5            asm("D1Ar5") = in_arg5;
> +	register int system_call     asm("D0Ar6") = in_system_call;
> +	register int result          asm("D0Re0");
> +	register int errno           asm("D1Re0");
> +
> +	asm volatile (
> +		"MSETL	[A0StP++], %7,%5,%3\n\t"
> +		"ADD	A0StP, A0StP, #8\n\t"
> +		"SWITCH	#0x0C00208\n\t"
> +		"GETL	%0, %1, [A0StP+#-8]\n\t"
> +		"SUB	A0StP, A0StP, #(4*6)+8\n\t"
> +		: "=r" (result),
> +		  "=r" (errno)
> +		: "r" (arg1),
> +		  "r" (arg2),
> +		  "r" (arg3),
> +		  "r" (arg4),
> +		  "r" (arg5),
> +		  "r" (system_call)
> +		: "memory");
> +
> +	if (fserrno)
> +		*fserrno = errno;
> +
> +	return result;
> +}
> +
> +struct dafs_inode_info {
> +	int fd;
> +	int mode;
> +	struct inode vfs_inode;
> +};
> +
> +static inline struct dafs_inode_info *DAFS_I(struct inode *inode)
> +{
> +	return container_of(inode, struct dafs_inode_info, vfs_inode);
> +}
> +
> +#define FILE_DAFS_I(file) DAFS_I((file)->f_path.dentry->d_inode)
> +
> +static int dafs_d_delete(const struct dentry *dentry)
> +{
> +	return 1;
> +}
> +
> +static const struct dentry_operations dafs_dentry_ops = {
> +	.d_delete		= dafs_d_delete,
> +};
> +
> +#define DAFS_SUPER_MAGIC 0xdadadaf5
> +
> +static const struct inode_operations dafs_iops;
> +static const struct inode_operations dafs_dir_iops;
> +
> +static char *__dentry_name(struct dentry *dentry, char *name)
> +{
> +	char *p = dentry_path_raw(dentry, name, PATH_MAX);
> +	char *root;
> +	size_t len;
> +
> +	root = dentry->d_sb->s_fs_info;
> +	len = strlen(root);
> +	if (IS_ERR(p)) {
> +		__putname(name);
> +		return NULL;
> +	}
> +
> +	strlcpy(name, root, PATH_MAX);
> +	if (len > p - name) {
> +		__putname(name);
> +		return NULL;
> +	}
> +	if (p > name + len) {
> +		char *s = name + len;
> +		while ((*s++ = *p++) != '\0')
> +			;
> +	}
> +	return name;
> +}
> +
> +static char *dentry_name(struct dentry *dentry)
> +{
> +	char *name = __getname();
> +	if (!name)
> +		return NULL;
> +
> +	return __dentry_name(dentry, name); /* will unlock */
> +}
> +
> +static int stat_file(const char *path, struct da_stat *p, int fd)
> +{
> +	int ret;
> +	int fserrno;
> +	memset(p, 0, sizeof(*p));
> +
> +	if (fd >= 0) {
> +		ret = fscall(DA_OP_FSTAT, fd, (int)p, 0, 0, 0, &fserrno);
> +		if (ret < 0) {
> +			/* Some versions of Codescape do not fill out errno. */
> +			if (ret < 0 && fserrno == 0)
> +				fserrno = ENOENT;
> +			return -fserrno;
> +		}
> +	} else {
> +		ret = fscall(DA_OP_STAT, (int)path, (int)p, strlen(path), 0, 0,
> +			     &fserrno);
> +		if (ret < 0) {
> +			/* Some versions of Codescape do not fill out errno. */
> +			if (ret < 0 && fserrno == 0)
> +				fserrno = ENOENT;
> +			return -fserrno;
> +		}
> +	}
> +
> +	return 0;
> +}
> +
> +static struct inode *dafs_iget(struct super_block *sb)
> +{
> +	struct inode *inode = new_inode(sb);
> +	if (!inode)
> +		return ERR_PTR(-ENOMEM);
> +	return inode;
> +}
> +
> +static struct inode *dafs_alloc_inode(struct super_block *sb)
> +{
> +	struct dafs_inode_info *hi;
> +
> +	hi = kzalloc(sizeof(*hi), GFP_KERNEL);
> +	if (hi == NULL)
> +		return NULL;
> +
> +	hi->fd = -1;
> +	inode_init_once(&hi->vfs_inode);
> +	return &hi->vfs_inode;
> +}
> +
> +static void close_file(void *stream)
> +{
> +	int fd = *((int *) stream);
> +
> +	fscall(DA_OP_CLOSE, fd, 0, 0, 0, 0, NULL);
> +}
> +
> +static void dafs_evict_inode(struct inode *inode)
> +{
> +	truncate_inode_pages(&inode->i_data, 0);
> +	clear_inode(inode);
> +	if (DAFS_I(inode)->fd != -1) {
> +		close_file(&DAFS_I(inode)->fd);
> +		DAFS_I(inode)->fd = -1;
> +	}
> +}
> +
> +static void dafs_i_callback(struct rcu_head *head)
> +{
> +	struct inode *inode = container_of(head, struct inode, i_rcu);
> +	kfree(DAFS_I(inode));
> +}
> +
> +static void dafs_destroy_inode(struct inode *inode)
> +{
> +	call_rcu(&inode->i_rcu, dafs_i_callback);
> +}
> +
> +static const struct super_operations dafs_sbops = {
> +	.alloc_inode	= dafs_alloc_inode,
> +	.drop_inode	= generic_delete_inode,
> +	.evict_inode	= dafs_evict_inode,
> +	.destroy_inode	= dafs_destroy_inode,
> +};
> +
> +static int open_dir(char *path, struct da_finddata *finddata, int *fserrno)
> +{
> +	int len = strlen(path);
> +	char buf[len + 3];
> +
> +	strcpy(buf, path);
> +	if (buf[len - 1] != '/')
> +		strcat(buf, "/*");
> +	else
> +		strcat(buf, "*");
> +
> +	return fscall(DA_OP_FINDFIRST, (int)buf, (int)finddata, 0, 0, 0,
> +		      fserrno);
> +}
> +
> +static void close_dir(int handle)
> +{
> +	fscall(DA_OP_FINDCLOSE, handle, 0, 0, 0, 0, NULL);
> +}
> +
> +static int read_dir(int handle, struct da_finddata *finddata)
> +{
> +	return fscall(DA_OP_FINDNEXT, handle, (int)finddata, 0, 0, 0, NULL);
> +}
> +
> +static int dafs_readdir(struct file *file, void *ent, filldir_t filldir)
> +{
> +	struct inode *inode = file->f_path.dentry->d_inode;
> +	struct super_block *sb = inode->i_sb;
> +	char *name;
> +	int handle;
> +	int fserrno;
> +	unsigned long long next, ino;
> +	int error = 0;
> +	struct da_finddata finddata;
> +
> +	name = dentry_name(file->f_path.dentry);
> +	if (name == NULL)
> +		return -ENOMEM;
> +	handle = open_dir(name, &finddata, &fserrno);
> +	__putname(name);
> +	if (handle == -1)
> +		return -fserrno;
> +
> +	next = 1;
> +
> +	if (file->f_pos == 0) {
> +		error = (*filldir)(ent, ".", file->f_pos + 1,
> +				   file->f_pos, inode->i_ino,
> +				   DT_DIR);
> +		if (error < 0)
> +			goto out;
> +		file->f_pos++;
> +	}
> +
> +	while (1) {
> +		error = read_dir(handle, &finddata);
> +		if (error)
> +			break;
> +
> +		if (next >= file->f_pos) {
> +			size_t len = strlen(finddata.name);
> +			ino = iunique(sb, 100);
> +			error = (*filldir)(ent, finddata.name, len,
> +					   file->f_pos, ino,
> +					   (finddata.attrib & _A_SUBDIR) ?
> +					    DT_DIR : DT_REG);
> +			if (error)
> +				break;
> +			file->f_pos++;
> +		}
> +		next++;
> +	}
> +out:
> +	close_dir(handle);
> +	return 0;
> +}
> +
> +static int dafs_file_open(struct inode *ino, struct file *file)
> +{
> +	static DEFINE_MUTEX(open_mutex);
> +	char *name;
> +	int mode, fmode, flags = 0, r = 0, w = 0, fd;
> +	int cpu;
> +
> +	fmode = file->f_mode & (FMODE_READ | FMODE_WRITE);
> +	if ((fmode & DAFS_I(ino)->mode) == fmode)
> +		return 0;
> +
> +	mode = ino->i_mode & (DA_S_IWUSR | DA_S_IRUSR);
> +
> +	mode |= DAFS_I(ino)->mode;
> +
> +	DAFS_I(ino)->mode |= fmode;
> +	if (DAFS_I(ino)->mode & FMODE_READ)
> +		r = 1;
> +	if (DAFS_I(ino)->mode & FMODE_WRITE) {
> +		w = 1;
> +		r = 1;
> +	}
> +
> +retry:
> +	if (r && !w)
> +		flags |= DA_O_RDONLY;
> +	else if (!r && w)
> +		flags |= DA_O_WRONLY;
> +	else if (r && w)
> +		flags |= DA_O_RDWR;
> +
> +	if (file->f_flags & O_CREAT)
> +		flags |= DA_O_CREAT;
> +
> +	if (file->f_flags & O_TRUNC)
> +		flags |= DA_O_TRUNC;
> +
> +	/*
> +	 * Set the affinity for this file handle to all CPUs. If we
> +	 * don't do this then, if the process that opened the file
> +	 * migrates to a different cpu, the FileServer will not accept
> +	 * the file handle.
> +	 */
> +	for_each_possible_cpu(cpu) {
> +		u8 hwthread = cpu_2_hwthread_id[cpu];
> +		flags |= (1 << (DA_O_AFFINITY_SHIFT + hwthread));
> +	}
> +
> +	name = dentry_name(file->f_path.dentry);
> +	if (name == NULL)
> +		return -ENOMEM;
> +
> +	fd = fscall(DA_OP_OPEN, (int)name, flags, mode, strlen(name), 0, NULL);
> +	__putname(name);
> +	if (fd < 0)
> +		return fd;
> +
> +	mutex_lock(&open_mutex);
> +	/* somebody else had handled it first? */
> +	if ((mode & DAFS_I(ino)->mode) == mode) {
> +		mutex_unlock(&open_mutex);
> +		return 0;
> +	}
> +	if ((mode | DAFS_I(ino)->mode) != mode) {
> +		mode |= DAFS_I(ino)->mode;
> +		mutex_unlock(&open_mutex);
> +		close_file(&fd);
> +		goto retry;
> +	}
> +	DAFS_I(ino)->fd = fd;
> +	DAFS_I(ino)->mode = mode;
> +	mutex_unlock(&open_mutex);
> +
> +	return 0;
> +}
> +
> +static const struct file_operations dafs_file_fops = {
> +	.llseek		= generic_file_llseek,
> +	.read		= do_sync_read,
> +	.splice_read	= generic_file_splice_read,
> +	.aio_read	= generic_file_aio_read,
> +	.aio_write	= generic_file_aio_write,
> +	.write		= do_sync_write,
> +	.mmap		= generic_file_mmap,
> +	.open		= dafs_file_open,
> +	.release	= NULL,
> +};
> +
> +static const struct file_operations dafs_dir_fops = {
> +	.llseek		= generic_file_llseek,
> +	.readdir	= dafs_readdir,
> +	.read		= generic_read_dir,
> +};
> +
> +static int read_file(int fd, unsigned long long *offset, const char *buf,
> +		     int len)
> +{
> +	int n;
> +	int fserrno;
> +
> +	n = fscall(DA_OP_PREAD, fd, (int)buf, len, (int)*offset, 0, &fserrno);
> +
> +	if (n < 0)
> +		return -fserrno;
> +
> +	return n;
> +}
> +
> +static int write_file(int fd, unsigned long long *offset, const char *buf,
> +		      int len)
> +{
> +	int n;
> +	int fserrno;
> +
> +	n = fscall(DA_OP_PWRITE, fd, (int)buf, len, (int)*offset, 0, &fserrno);
> +
> +	if (n < 0)
> +		return -fserrno;
> +
> +	return n;
> +}
> +
> +static int dafs_writepage(struct page *page, struct writeback_control *wbc)
> +{
> +	struct address_space *mapping = page->mapping;
> +	struct inode *inode = mapping->host;
> +	char *buffer;
> +	unsigned long long base;
> +	int count = PAGE_CACHE_SIZE;
> +	int end_index = inode->i_size >> PAGE_CACHE_SHIFT;
> +	int err;
> +
> +	if (page->index >= end_index)
> +		count = inode->i_size & (PAGE_CACHE_SIZE-1);
> +
> +	buffer = kmap(page);
> +	base = ((unsigned long long) page->index) << PAGE_CACHE_SHIFT;
> +
> +	err = write_file(DAFS_I(inode)->fd, &base, buffer, count);
> +	if (err != count) {
> +		ClearPageUptodate(page);
> +		goto out;
> +	}
> +
> +	if (base > inode->i_size)
> +		inode->i_size = base;
> +
> +	if (PageError(page))
> +		ClearPageError(page);
> +	err = 0;
> +
> + out:
> +	kunmap(page);
> +
> +	unlock_page(page);
> +	return err;
> +}
> +
> +static int dafs_readpage(struct file *file, struct page *page)
> +{
> +	char *buffer;
> +	long long start;
> +	int err = 0;
> +
> +	start = (long long) page->index << PAGE_CACHE_SHIFT;
> +	buffer = kmap(page);
> +	err = read_file(FILE_DAFS_I(file)->fd, &start, buffer,
> +			PAGE_CACHE_SIZE);
> +	if (err < 0)
> +		goto out;
> +
> +	memset(&buffer[err], 0, PAGE_CACHE_SIZE - err);
> +
> +	flush_dcache_page(page);
> +	SetPageUptodate(page);
> +	if (PageError(page))
> +		ClearPageError(page);
> +	err = 0;
> + out:
> +	kunmap(page);
> +	unlock_page(page);
> +	return err;
> +}
> +
> +static int dafs_write_begin(struct file *file, struct address_space *mapping,
> +			loff_t pos, unsigned len, unsigned flags,
> +			struct page **pagep, void **fsdata)
> +{
> +	pgoff_t index = pos >> PAGE_CACHE_SHIFT;
> +
> +	*pagep = grab_cache_page_write_begin(mapping, index, flags);
> +	if (!*pagep)
> +		return -ENOMEM;
> +	return 0;
> +}
> +
> +static int dafs_write_end(struct file *file, struct address_space *mapping,
> +			loff_t pos, unsigned len, unsigned copied,
> +			struct page *page, void *fsdata)
> +{
> +	struct inode *inode = mapping->host;
> +	void *buffer;
> +	unsigned from = pos & (PAGE_CACHE_SIZE - 1);
> +	int err;
> +
> +	buffer = kmap(page);
> +	err = write_file(FILE_DAFS_I(file)->fd, &pos, buffer + from, copied);
> +	kunmap(page);
> +
> +	if (!PageUptodate(page) && err == PAGE_CACHE_SIZE)
> +		SetPageUptodate(page);
> +
> +	/*
> +	 * If err > 0, write_file has added err to pos, so we are comparing
> +	 * i_size against the last byte written.
> +	 */
> +	if (err > 0 && (pos > inode->i_size))
> +		inode->i_size = pos;
> +	unlock_page(page);
> +	page_cache_release(page);
> +
> +	return err;
> +}
> +
> +static const struct address_space_operations dafs_aops = {
> +	.writepage	= dafs_writepage,
> +	.readpage	= dafs_readpage,
> +	.set_page_dirty	= __set_page_dirty_nobuffers,
> +	.write_begin	= dafs_write_begin,
> +	.write_end	= dafs_write_end,
> +};
> +
> +static int read_name(struct inode *ino, char *name)
> +{
> +	dev_t rdev;
> +	struct da_stat st;
> +	int err = stat_file(name, &st, -1);
> +	if (err)
> +		return err;
> +
> +	/* No valid maj and min from DA.*/
> +	rdev = MKDEV(0, 0);
> +
> +	switch (st.st_mode & S_IFMT) {
> +	case S_IFDIR:
> +		ino->i_op = &dafs_dir_iops;
> +		ino->i_fop = &dafs_dir_fops;
> +		break;
> +	case S_IFCHR:
> +	case S_IFBLK:
> +	case S_IFIFO:
> +	case S_IFSOCK:
> +		init_special_inode(ino, st.st_mode & S_IFMT, rdev);
> +		ino->i_op = &dafs_iops;
> +		break;
> +
> +	case S_IFLNK:
> +	default:
> +		ino->i_op = &dafs_iops;
> +		ino->i_fop = &dafs_file_fops;
> +		ino->i_mapping->a_ops = &dafs_aops;
> +	}
> +
> +	ino->i_ino = st.st_ino;
> +	ino->i_mode = st.st_mode;
> +	set_nlink(ino, st.st_nlink);
> +
> +	i_uid_write(ino, st.st_uid);
> +	i_gid_write(ino, st.st_gid);
> +	ino->i_atime.tv_sec = st.st_atime;
> +	ino->i_atime.tv_nsec = 0;
> +	ino->i_mtime.tv_sec = st.st_mtime;
> +	ino->i_mtime.tv_nsec = 0;
> +	ino->i_ctime.tv_sec = st.st_ctime;
> +	ino->i_ctime.tv_nsec = 0;
> +	ino->i_size = st.st_size;
> +	ino->i_blocks = st.st_blocks;
> +	return 0;
> +}
> +
> +static int dafs_create(struct inode *dir, struct dentry *dentry, umode_t mode,
> +		       bool excl)
> +{
> +	struct inode *inode;
> +	char *name;
> +	int error, fd;
> +	int damode;
> +	int creat_flags = DA_O_TRUNC | DA_O_CREAT | DA_O_WRONLY;
> +	int cpu;
> +
> +	inode = dafs_iget(dir->i_sb);
> +	if (IS_ERR(inode)) {
> +		error = PTR_ERR(inode);
> +		goto out;
> +	}
> +
> +	damode = mode & (DA_S_IWUSR | DA_S_IRUSR);
> +
> +	error = -ENOMEM;
> +	name = dentry_name(dentry);
> +	if (name == NULL)
> +		goto out_put;
> +
> +	/*
> +	 * creat() will only create text mode files on a Windows host
> +	 * at present.  Replicate the creat() functionality with an
> +	 * open() call, which always creates binary files. Set the
> +	 * affinity to all hardware threads.
> +	 */
> +	for_each_possible_cpu(cpu) {
> +		u8 hwthread = cpu_2_hwthread_id[cpu];
> +		creat_flags |= (1 << (DA_O_AFFINITY_SHIFT + hwthread));
> +	}
> +
> +	fd = fscall(DA_OP_OPEN, (int)name, creat_flags, damode, strlen(name),
> +		    0, NULL);
> +	if (fd < 0)
> +		error = fd;
> +	else
> +		error = read_name(inode, name);
> +
> +	kfree(name);
> +	if (error)
> +		goto out_put;
> +
> +	DAFS_I(inode)->fd = fd;
> +	DAFS_I(inode)->mode = FMODE_READ | FMODE_WRITE;
> +	d_instantiate(dentry, inode);
> +	return 0;
> +
> + out_put:
> +	iput(inode);
> + out:
> +	return error;
> +}
> +
> +static struct dentry *dafs_lookup(struct inode *ino, struct dentry *dentry,
> +				  unsigned int flags)
> +{
> +	struct inode *inode;
> +	char *name;
> +	int err;
> +
> +	inode = dafs_iget(ino->i_sb);
> +	if (IS_ERR(inode)) {
> +		err = PTR_ERR(inode);
> +		goto out;
> +	}
> +
> +	err = -ENOMEM;
> +	name = dentry_name(dentry);
> +	if (name == NULL)
> +		goto out_put;
> +
> +	err = read_name(inode, name);
> +
> +	__putname(name);
> +	if (err == -ENOENT) {
> +		iput(inode);
> +		inode = NULL;
> +	} else if (err)
> +		goto out_put;
> +
> +	d_add(dentry, inode);
> +	return NULL;
> +
> + out_put:
> +	iput(inode);
> + out:
> +	return ERR_PTR(err);
> +}
> +
> +static int dafs_link(struct dentry *to, struct inode *ino, struct dentry *from)
> +{
> +	char *from_name, *to_name;
> +	int err;
> +
> +	from_name = dentry_name(from);
> +	if (from_name == NULL)
> +		return -ENOMEM;
> +	to_name = dentry_name(to);
> +	if (to_name == NULL) {
> +		__putname(from_name);
> +		return -ENOMEM;
> +	}
> +	err = -EINVAL;
> +	__putname(from_name);
> +	__putname(to_name);
> +	return err;
> +}
> +
> +static int dafs_unlink(struct inode *ino, struct dentry *dentry)
> +{
> +	char *file;
> +	int err;
> +	int fserrno;
> +
> +	file = dentry_name(dentry);
> +	if (file == NULL)
> +		return -ENOMEM;
> +
> +	err = fscall(DA_OP_UNLINK, (int)file, 0, 0, 0, 0, &fserrno);
> +	__putname(file);
> +	if (err)
> +		return -fserrno;
> +	return 0;
> +}
> +
> +static int do_mkdir(const char *file, int mode)
> +{
> +	int err;
> +	int fserrno;
> +
> +	err = fscall(DA_OP_MKDIR, (int)file, mode, strlen(file), 0, 0,
> +		     &fserrno);
> +	if (err)
> +		return -fserrno;
> +	return 0;
> +}
> +
> +static int dafs_mkdir(struct inode *ino, struct dentry *dentry, umode_t mode)
> +{
> +	char *file;
> +	int err;
> +
> +	file = dentry_name(dentry);
> +	if (file == NULL)
> +		return -ENOMEM;
> +	err = do_mkdir(file, mode);
> +	__putname(file);
> +	return err;
> +}
> +
> +static int do_rmdir(const char *file)
> +{
> +	int err;
> +	int fserrno;
> +
> +	err = fscall(DA_OP_RMDIR, (int)file, strlen(file), 0, 0, 0, &fserrno);
> +	if (err)
> +		return -fserrno;
> +	return 0;
> +}
> +
> +static int dafs_rmdir(struct inode *ino, struct dentry *dentry)
> +{
> +	char *file;
> +	int err;
> +
> +	file = dentry_name(dentry);
> +	if (file == NULL)
> +		return -ENOMEM;
> +	err = do_rmdir(file);
> +	__putname(file);
> +	return err;
> +}
> +
> +static int dafs_rename(struct inode *from_ino, struct dentry *from,
> +		  struct inode *to_ino, struct dentry *to)
> +{
> +	char *from_name, *to_name;
> +	int err;
> +
> +	from_name = dentry_name(from);
> +	if (from_name == NULL)
> +		return -ENOMEM;
> +	to_name = dentry_name(to);
> +	if (to_name == NULL) {
> +		__putname(from_name);
> +		return -ENOMEM;
> +	}
> +	err = -EINVAL;
> +	__putname(from_name);
> +	__putname(to_name);
> +	return err;
> +}
> +
> +static const struct inode_operations dafs_iops = {
> +	.create		= dafs_create,
> +	.link		= dafs_link,
> +	.unlink		= dafs_unlink,
> +	.mkdir		= dafs_mkdir,
> +	.rmdir		= dafs_rmdir,
> +	.rename		= dafs_rename,
> +};
> +
> +static const struct inode_operations dafs_dir_iops = {
> +	.create		= dafs_create,
> +	.lookup		= dafs_lookup,
> +	.link		= dafs_link,
> +	.unlink		= dafs_unlink,
> +	.mkdir		= dafs_mkdir,
> +	.rmdir		= dafs_rmdir,
> +	.rename		= dafs_rename,
> +};
> +
> +static char *host_root_path = ".";
> +
> +static int dafs_fill_sb_common(struct super_block *sb, void *d, int silent)
> +{
> +	struct inode *root_inode;
> +	int err;
> +
> +	sb->s_blocksize = 1024;
> +	sb->s_blocksize_bits = 10;
> +	sb->s_magic = DAFS_SUPER_MAGIC;
> +	sb->s_op = &dafs_sbops;
> +	sb->s_d_op = &dafs_dentry_ops;
> +	sb->s_maxbytes = MAX_LFS_FILESIZE;
> +
> +	err = -ENOMEM;
> +
> +	root_inode = new_inode(sb);
> +	if (!root_inode)
> +		goto out;
> +
> +	err = read_name(root_inode, host_root_path);
> +	if (err)
> +		goto out_put;
> +
> +	err = -ENOMEM;
> +	sb->s_fs_info = host_root_path;
> +	sb->s_root = d_make_root(root_inode);
> +	if (sb->s_root == NULL)
> +		goto out;
> +
> +	return 0;
> +
> +out_put:
> +	iput(root_inode);
> +out:
> +	return err;
> +}
> +
> +static struct dentry *dafs_read_sb(struct file_system_type *type,
> +				   int flags, const char *dev_name,
> +				   void *data)
> +{
> +	if (!metag_da_enabled())
> +		return ERR_PTR(-ENODEV);
> +	return mount_nodev(type, flags, data, dafs_fill_sb_common);
> +}
> +
> +static struct file_system_type dafs_type = {
> +	.owner		= THIS_MODULE,
> +	.name		= "imgdafs",
> +	.mount		= dafs_read_sb,
> +	.kill_sb	= kill_anon_super,
> +	.fs_flags	= 0,
> +};
> +
> +static int __init init_dafs(void)
> +{
> +	return register_filesystem(&dafs_type);
> +}
> +
> +static void __exit exit_dafs(void)
> +{
> +	unregister_filesystem(&dafs_type);
> +}
> +
> +module_init(init_dafs)
> +module_exit(exit_dafs)
> +MODULE_LICENSE("GPL");
> 

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