1 files changed, 93 insertions, 0 deletions
diff --git a/fs/ext2/xip.c b/fs/ext2/xip.c
new file mode 100644
index 000000000000..ca7f00312388
--- /dev/null
+++ b/fs/ext2/xip.c
@@ -0,0 +1,93 @@
+/*
+ *  linux/fs/ext2/xip.c
+ *
+ * Copyright (C) 2005 IBM Corporation
+ * Author: Carsten Otte (cotte@de.ibm.com)
+ */
+
+#include <linux/mm.h>
+#include <linux/fs.h>
+#include <linux/genhd.h>
+#include <linux/buffer_head.h>
+#include <linux/ext2_fs_sb.h>
+#include <linux/ext2_fs.h>
+#include "ext2.h"
+#include "xip.h"
+
+static inline int
+__inode_direct_access(struct inode *inode, sector_t sector,
+		      unsigned long *data)
+{
+	BUG_ON(!inode->i_sb->s_bdev->bd_disk->fops->direct_access);
+	return inode->i_sb->s_bdev->bd_disk->fops
+		->direct_access(inode->i_sb->s_bdev,sector,data);
+}
+
+static inline int
+__ext2_get_sector(struct inode *inode, sector_t offset, int create,
+		   sector_t *result)
+{
+	struct buffer_head tmp;
+	int rc;
+
+	memset(&tmp, 0, sizeof(struct buffer_head));
+	rc = ext2_get_block(inode, offset/ (PAGE_SIZE/512), &tmp,
+			    create);
+	*result = tmp.b_blocknr;
+
+	/* did we get a sparse block (hole in the file)? */
+	if (!tmp.b_blocknr && !rc) {
+		BUG_ON(create);
+		rc = -ENODATA;
+	}
+
+	return rc;
+}
+
+int
+ext2_clear_xip_target(struct inode *inode, int block)
+{
+	sector_t sector = block * (PAGE_SIZE/512);
+	unsigned long data;
+	int rc;
+
+	rc = __inode_direct_access(inode, sector, &data);
+	if (!rc)
+		clear_page((void*)data);
+	return rc;
+}
+
+void ext2_xip_verify_sb(struct super_block *sb)
+{
+	struct ext2_sb_info *sbi = EXT2_SB(sb);
+
+	if ((sbi->s_mount_opt & EXT2_MOUNT_XIP) &&
+	    !sb->s_bdev->bd_disk->fops->direct_access) {
+		sbi->s_mount_opt &= (~EXT2_MOUNT_XIP);
+		ext2_warning(sb, __FUNCTION__,
+			     "ignoring xip option - not supported by bdev");
+	}
+}
+
+struct page *
+ext2_get_xip_page(struct address_space *mapping, sector_t offset,
+		   int create)
+{
+	int rc;
+	unsigned long data;
+	sector_t sector;
+
+	/* first, retrieve the sector number */
+	rc = __ext2_get_sector(mapping->host, offset, create, &sector);
+	if (rc)
+		goto error;
+
+	/* retrieve address of the target data */
+	rc = __inode_direct_access
+		(mapping->host, sector * (PAGE_SIZE/512), &data);
+	if (!rc)
+		return virt_to_page(data);
+
+ error:
+	return ERR_PTR(rc);
+}