1 files changed, 102 insertions, 0 deletions
diff --git a/fs/msdos/mmap.c b/fs/msdos/mmap.c
new file mode 100644
index 000000000..0e85584e9
--- /dev/null
+++ b/fs/msdos/mmap.c
@@ -0,0 +1,102 @@
+/*
+ *	fs/msdos/mmap.c
+ *
+ *	Written by Jacques Gelinas (jacques@solucorp.qc.ca)
+ *	Inspired by fs/nfs/mmap.c (Jaon Tombs 15 Aug 1993)
+ *
+ *	msdos mmap handling
+ */
+#include <linux/stat.h>
+#include <linux/sched.h>
+#include <linux/kernel.h>
+#include <linux/mm.h>
+#include <linux/shm.h>
+#include <linux/errno.h>
+#include <linux/mman.h>
+#include <linux/string.h>
+#include <linux/malloc.h>
+#include <asm/segment.h>
+#include <asm/system.h>
+#include <linux/msdos_fs.h>
+
+/*
+ * Fill in the supplied page for mmap
+ */
+static unsigned long msdos_file_mmap_nopage(
+	struct vm_area_struct * area,
+	unsigned long address,
+	unsigned long page,
+	int error_code)
+{
+	struct inode * inode = area->vm_inode;
+	unsigned int clear;
+	int pos;
+	long gap;	/* distance from eof to pos */
+
+	address &= PAGE_MASK;
+	pos = address - area->vm_start + area->vm_offset;
+
+	clear = 0;
+	gap = inode->i_size - pos;
+	if (gap <= 0){
+		/* mmaping beyond end of file */
+		clear = PAGE_SIZE;
+	}else{
+		int cur_read;
+		int need_read;
+		struct file filp;
+		if (gap < PAGE_SIZE){
+			clear = PAGE_SIZE - gap;
+		}
+		filp.f_pos = pos;
+		need_read = PAGE_SIZE - clear;
+		{
+			unsigned long cur_fs = get_fs();
+			set_fs (KERNEL_DS);
+			cur_read = msdos_file_read (inode,&filp,(char*)page
+				,need_read);
+			set_fs (cur_fs);
+		}
+		if (cur_read != need_read){
+			printk ("MSDOS: Error while reading an mmap file %d <> %d\n"
+				,cur_read,need_read);
+		}
+	}
+	if (clear > 0){
+		memset ((char*)page+PAGE_SIZE-clear,0,clear);
+	}
+	return page;
+}
+
+struct vm_operations_struct msdos_file_mmap = {
+	NULL,			/* open */
+	NULL,			/* close */
+	msdos_file_mmap_nopage,	/* nopage */
+	NULL,			/* wppage */
+	NULL,			/* share */
+	NULL,			/* unmap */
+};
+
+/*
+ * This is used for a general mmap of an msdos file
+ * Returns 0 if ok, or a negative error code if not.
+ */
+int msdos_mmap(struct inode * inode, struct file * file, struct vm_area_struct * vma)
+{
+	if (vma->vm_page_prot & PAGE_RW)	/* only PAGE_COW or read-only supported now */
+		return -EINVAL;
+	if (vma->vm_offset & (inode->i_sb->s_blocksize - 1))
+		return -EINVAL;
+	if (!inode->i_sb || !S_ISREG(inode->i_mode))
+		return -EACCES;
+	if (!IS_RDONLY(inode)) {
+		inode->i_atime = CURRENT_TIME;
+		inode->i_dirt = 1;
+	}
+
+	vma->vm_inode = inode;
+	inode->i_count++;
+	vma->vm_ops = &msdos_file_mmap;
+	return 0;
+}
+