Message-ID: <1374854132-8159-1-git-send-email-james.hogan@imgtec.com>
Date:	Fri, 26 Jul 2013 16:55:32 +0100
From:	James Hogan <james.hogan@...tec.com>
To:	Alexander Viro <viro@...iv.linux.org.uk>,
	<linux-fsdevel@...r.kernel.org>, <linux-kernel@...r.kernel.org>
CC:	James Hogan <james.hogan@...tec.com>
Subject: [PATCH v9] fs: imgdafs: Add IMG DAFS filesystem for metag

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: linux-fsdevel@...r.kernel.org
---
v9:
  * updated dafs_readdir to use iterate() file operation and dir_emit()
    to match changes in v3.11-rc1.

v8:
  * enabled building as a module (commit e605ff8 merged during v3.10
    merge window exports the necessary symbols)

v7:
  * use explicit sized types in da_stat and da_finddata (Al Viro)
  * move IMGDAFS_SUPER_MAGIC to <linux/magic.h> (Al Viro)
  * use fmode_t instead of int in a couple of places (Al Viro)
  * removed "will unlock" comment (Al Viro)
  * use kmalloc and init hi->mode explicitly (Al Viro)
  * kmalloc instead of using dynamic array for path (Al Viro)
  * use file_inode() helper in dafs_readdir (Al Viro)

v6:
  * use file_inode() helper introduced in v3.9-rc1
  * remove dafs_iops as it only contained directory methods
  * add MODULE_ALIAS_FS()

v5:
  * removed arch/metag changes (the arch/metag patchset it was
    previously part of is now mainline with those changes)

v4:
  * clean up fscall similarly to chancall in tty/metag_da

v2:
  * fixed fserrno problem (Al Viro)
  * renamed to imgdafs

 fs/Kconfig                 |   1 +
 fs/Makefile                |   1 +
 fs/imgdafs/Kconfig         |   6 +
 fs/imgdafs/Makefile        |   7 +
 fs/imgdafs/imgdafs.h       |  82 +++++
 fs/imgdafs/inode.c         | 837 +++++++++++++++++++++++++++++++++++++++++++++
 include/uapi/linux/magic.h |   1 +
 7 files changed, 935 insertions(+)
 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/fs/Kconfig b/fs/Kconfig
index c229f82..839ef10 100644
--- a/fs/Kconfig
+++ b/fs/Kconfig
@@ -212,6 +212,7 @@ source "fs/ufs/Kconfig"
 source "fs/exofs/Kconfig"
 source "fs/f2fs/Kconfig"
 source "fs/efivarfs/Kconfig"
+source "fs/imgdafs/Kconfig"
 
 endif # MISC_FILESYSTEMS
 
diff --git a/fs/Makefile b/fs/Makefile
index 4fe6df3..25a93c7 100644
--- a/fs/Makefile
+++ b/fs/Makefile
@@ -126,3 +126,4 @@ obj-y				+= exofs/ # Multiple modules
 obj-$(CONFIG_CEPH_FS)		+= ceph/
 obj-$(CONFIG_PSTORE)		+= pstore/
 obj-$(CONFIG_EFIVAR_FS)		+= efivarfs/
+obj-$(CONFIG_IMGDAFS_FS)	+= imgdafs/
diff --git a/fs/imgdafs/Kconfig b/fs/imgdafs/Kconfig
new file mode 100644
index 0000000..844e6cf
--- /dev/null
+++ b/fs/imgdafs/Kconfig
@@ -0,0 +1,6 @@
+config IMGDAFS_FS
+	tristate "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..0350220
--- /dev/null
+++ b/fs/imgdafs/imgdafs.h
@@ -0,0 +1,82 @@
+#ifndef _IMGDAFS_H_
+#define _IMGDAFS_H_
+
+#include <linux/types.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 {
+	s16 st_dev;
+	u16 st_ino;
+	u32 st_mode;
+	u16 st_nlink;
+	u16 st_uid;
+	u16 st_gid;
+	s16 st_rdev;
+	s32 st_size;
+	s32 st_atime;
+	s32 st_spare1;
+	s32 st_mtime;
+	s32 st_spare2;
+	s32 st_ctime;
+	s32 st_spare3;
+	s32 st_blksize;
+	s32 st_blocks;
+	s32 st_spare4[2];
+};
+
+#define _A_SUBDIR 0x10
+
+struct da_finddata {
+	u32 size;
+	u32 attrib;
+	u8 name[260];
+};
+
+#endif
diff --git a/fs/imgdafs/inode.c b/fs/imgdafs/inode.c
new file mode 100644
index 0000000..9118f13
--- /dev/null
+++ b/fs/imgdafs/inode.c
@@ -0,0 +1,837 @@
+/*
+ * Copyright (C) 2008-2013 Imagination Technologies Ltd.
+ * Licensed under the GPL
+ *
+ * Based on hostfs for UML.
+ *
+ */
+
+#include <linux/fs.h>
+#include <linux/magic.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;
+	fmode_t 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_inode(file))
+
+static int dafs_d_delete(const struct dentry *dentry)
+{
+	return 1;
+}
+
+static const struct dentry_operations dafs_dentry_ops = {
+	.d_delete		= dafs_d_delete,
+};
+
+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);
+}
+
+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 = kmalloc(sizeof(*hi), GFP_KERNEL);
+	if (hi == NULL)
+		return NULL;
+
+	hi->fd = -1;
+	hi->mode = 0;
+	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;
+	int ret;
+
+	buf = kmalloc(len + 3, GFP_KERNEL);
+	if (!buf) {
+		*fserrno = ENOMEM;
+		return -1;
+	}
+
+	strcpy(buf, path);
+	if (buf[len - 1] != '/')
+		strcat(buf, "/*");
+	else
+		strcat(buf, "*");
+
+	ret = fscall(DA_OP_FINDFIRST, (int)buf, (int)finddata, 0, 0, 0,
+		     fserrno);
+	kfree(buf);
+	return ret;
+}
+
+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, struct dir_context *ctx)
+{
+	struct inode *inode = file_inode(file);
+	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 (ctx->pos == 0) {
+		if (!dir_emit(ctx, ".", ctx->pos + 1, inode->i_ino, DT_DIR))
+			goto out;
+		ctx->pos++;
+	}
+
+	while (1) {
+		error = read_dir(handle, &finddata);
+		if (error)
+			break;
+
+		if (next >= ctx->pos) {
+			size_t len = strlen(finddata.name);
+			ino = iunique(sb, 100);
+			if (!dir_emit(ctx, finddata.name, len, ino,
+				      (finddata.attrib & _A_SUBDIR) ?
+				      DT_DIR : DT_REG))
+				break;
+			ctx->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;
+	fmode_t mode, fmode;
+	int 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,
+	.iterate	= 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);
+		break;
+
+	case S_IFLNK:
+	default:
+		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_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 = IMGDAFS_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,
+};
+MODULE_ALIAS_FS("imgdafs");
+
+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");
diff --git a/include/uapi/linux/magic.h b/include/uapi/linux/magic.h
index 2944278..0acdf2a 100644
--- a/include/uapi/linux/magic.h
+++ b/include/uapi/linux/magic.h
@@ -31,6 +31,7 @@
 #define PSTOREFS_MAGIC		0x6165676C
 #define EFIVARFS_MAGIC		0xde5e81e4
 #define HOSTFS_SUPER_MAGIC	0x00c0ffee
+#define IMGDAFS_SUPER_MAGIC	0xdadadaf5
 
 #define MINIX_SUPER_MAGIC	0x137F		/* minix v1 fs, 14 char names */
 #define MINIX_SUPER_MAGIC2	0x138F		/* minix v1 fs, 30 char names */
-- 
1.8.1.2


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