pramfs: XIP operations

diff -Nurp linux-2.6.36-orig/fs/pramfs/xip.c linux-2.6.36/fs/pramfs/xip.c
@@ -0,0 +1,90 @@
+/*
+ * FILE NAME fs/pramfs/xip.c
+ *
+ * BRIEF DESCRIPTION
+ *
+ * XIP operations.
+ *
+ * Copyright 2009-2010 Marco Stornelli <[email protected]>
+ * This file is licensed under the terms of the GNU General Public
+ * License version 2. This program is licensed "as is" without any
+ * warranty of any kind, whether express or implied.
+ */
+
+#include <linux/mm.h>
+#include <linux/fs.h>
+#include <linux/genhd.h>
+#include <linux/buffer_head.h>
+#include "pram.h"
+#include "xip.h"
+
+static int pram_find_and_alloc_blocks(struct inode *inode, sector_t iblock,
+				     sector_t *data_block, int create)
+{
+	int err = -EIO;
+	u64 block;
+
+	mutex_lock(&PRAM_I(inode)->truncate_lock);
+
+	block = pram_find_data_block(inode, iblock);
+
+	if (!block) {
+		if (!create) {
+			err = -ENODATA;
+			goto err;
+		}
+
+		err = pram_alloc_blocks(inode, iblock, 1);
+		if (err)
+			goto err;
+
+		block = pram_find_data_block(inode, iblock);
+		if (!block) {
+			err = -ENODATA;
+			goto err;
+		}
+	}
+
+	*data_block = block;
+	err = 0;
+
+ err:
+	mutex_unlock(&PRAM_I(inode)->truncate_lock);
+	return err;
+}
+
+
+static int __pram_get_block(struct inode *inode, pgoff_t pgoff, int create,
+		   sector_t *result)
+{
+	int rc = 0;
+	sector_t iblock;
+
+	/* find starting block number to access */
+	iblock = (sector_t)pgoff << (PAGE_CACHE_SHIFT - inode->i_blkbits);
+
+	rc = pram_find_and_alloc_blocks(inode, iblock, result, create);
+
+	if (rc == -ENODATA)
+		BUG_ON(create);
+
+	return rc;
+}
+
+int pram_get_xip_mem(struct address_space *mapping, pgoff_t pgoff, int create,
+				void **kmem, unsigned long *pfn)
+{
+	int rc;
+	sector_t block;
+
+	/* first, retrieve the block */
+	rc = __pram_get_block(mapping->host, pgoff, create, &block);
+	if (rc)
+		goto exit;
+
+	*kmem = pram_get_block(mapping->host->i_sb, block);
+	*pfn = page_to_pfn(virt_to_page((unsigned long)*kmem));
+
+exit:
+	return rc;
+}

diff -Nurp linux-2.6.36-orig/fs/pramfs/xip.h linux-2.6.36/fs/pramfs/xip.h
@@ -0,0 +1,24 @@
+/*
+ * FILE NAME fs/pramfs/xip.h
+ *
+ * BRIEF DESCRIPTION
+ *
+ * XIP operations.
+ *
+ * Copyright 2009-2010 Marco Stornelli <[email protected]>
+ * This file is licensed under the terms of the GNU General Public
+ * License version 2. This program is licensed "as is" without any
+ * warranty of any kind, whether express or implied.
+ */
+
+#ifdef CONFIG_PRAMFS_XIP
+
+int pram_get_xip_mem(struct address_space *, pgoff_t, int, void **,
+							      unsigned long *);
+
+#else
+
+#define pram_get_xip_mem NULL
+
+#endif
+