From 8e4bff4cab0ddac6060645b0715210484d02ff40 Mon Sep 17 00:00:00 2001
From: Yuval Adam <_@yuv.al>
Date: Wed, 30 Aug 2017 08:25:59 +0000
Subject: Initial file dump from open source release

---
 fs/ext2/xip.c | 91 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 91 insertions(+)
 create mode 100644 fs/ext2/xip.c

(limited to 'fs/ext2/xip.c')

diff --git a/fs/ext2/xip.c b/fs/ext2/xip.c
new file mode 100644
index 00000000..e98171a1
--- /dev/null
+++ b/fs/ext2/xip.c
@@ -0,0 +1,91 @@
+/*
+ *  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/blkdev.h>
+#include "ext2.h"
+#include "xip.h"
+
+static inline int
+__inode_direct_access(struct inode *inode, sector_t block,
+		      void **kaddr, unsigned long *pfn)
+{
+	struct block_device *bdev = inode->i_sb->s_bdev;
+	const struct block_device_operations *ops = bdev->bd_disk->fops;
+	sector_t sector;
+
+	sector = block * (PAGE_SIZE / 512); /* ext2 block to bdev sector */
+
+	BUG_ON(!ops->direct_access);
+	return ops->direct_access(bdev, sector, kaddr, pfn);
+}
+
+static inline int
+__ext2_get_block(struct inode *inode, pgoff_t pgoff, int create,
+		   sector_t *result)
+{
+	struct buffer_head tmp;
+	int rc;
+
+	memset(&tmp, 0, sizeof(struct buffer_head));
+	tmp.b_size = 1 << inode->i_blkbits;
+	rc = ext2_get_block(inode, pgoff, &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, sector_t block)
+{
+	void *kaddr;
+	unsigned long pfn;
+	int rc;
+
+	rc = __inode_direct_access(inode, block, &kaddr, &pfn);
+	if (!rc)
+		clear_page(kaddr);
+	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_msg(sb, KERN_WARNING,
+			     "warning: ignoring xip option - "
+			     "not supported by bdev");
+	}
+}
+
+int ext2_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 sector number */
+	rc = __ext2_get_block(mapping->host, pgoff, create, &block);
+	if (rc)
+		return rc;
+
+	/* retrieve address of the target data */
+	rc = __inode_direct_access(mapping->host, block, kmem, pfn);
+	return rc;
+}
-- 
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