1 /*
2 * linux/fs/ext2/xip.c
3 *
4 * Copyright (C) 2005 IBM Corporation
5 * Author: Carsten Otte (cotte@de.ibm.com)
6 */
7
8 #include <linux/mm.h>
9 #include <linux/fs.h>
10 #include <linux/genhd.h>
11 #include <linux/buffer_head.h>
12 #include <linux/ext2_fs_sb.h>
13 #include <linux/ext2_fs.h>
14 #include <linux/blkdev.h>
15 #include "ext2.h"
16 #include "xip.h"
17
18 static inline int
__inode_direct_access(struct inode * inode,sector_t block,void ** kaddr,unsigned long * pfn)19 __inode_direct_access(struct inode *inode, sector_t block,
20 void **kaddr, unsigned long *pfn)
21 {
22 struct block_device *bdev = inode->i_sb->s_bdev;
23 const struct block_device_operations *ops = bdev->bd_disk->fops;
24 sector_t sector;
25
26 sector = block * (PAGE_SIZE / 512); /* ext2 block to bdev sector */
27
28 BUG_ON(!ops->direct_access);
29 return ops->direct_access(bdev, sector, kaddr, pfn);
30 }
31
32 static inline int
__ext2_get_block(struct inode * inode,pgoff_t pgoff,int create,sector_t * result)33 __ext2_get_block(struct inode *inode, pgoff_t pgoff, int create,
34 sector_t *result)
35 {
36 struct buffer_head tmp;
37 int rc;
38
39 memset(&tmp, 0, sizeof(struct buffer_head));
40 rc = ext2_get_block(inode, pgoff, &tmp, create);
41 *result = tmp.b_blocknr;
42
43 /* did we get a sparse block (hole in the file)? */
44 if (!tmp.b_blocknr && !rc) {
45 BUG_ON(create);
46 rc = -ENODATA;
47 }
48
49 return rc;
50 }
51
52 int
ext2_clear_xip_target(struct inode * inode,sector_t block)53 ext2_clear_xip_target(struct inode *inode, sector_t block)
54 {
55 void *kaddr;
56 unsigned long pfn;
57 int rc;
58
59 rc = __inode_direct_access(inode, block, &kaddr, &pfn);
60 if (!rc)
61 clear_page(kaddr);
62 return rc;
63 }
64
ext2_xip_verify_sb(struct super_block * sb)65 void ext2_xip_verify_sb(struct super_block *sb)
66 {
67 struct ext2_sb_info *sbi = EXT2_SB(sb);
68
69 if ((sbi->s_mount_opt & EXT2_MOUNT_XIP) &&
70 !sb->s_bdev->bd_disk->fops->direct_access) {
71 sbi->s_mount_opt &= (~EXT2_MOUNT_XIP);
72 ext2_msg(sb, KERN_WARNING,
73 "warning: ignoring xip option - "
74 "not supported by bdev");
75 }
76 }
77
ext2_get_xip_mem(struct address_space * mapping,pgoff_t pgoff,int create,void ** kmem,unsigned long * pfn)78 int ext2_get_xip_mem(struct address_space *mapping, pgoff_t pgoff, int create,
79 void **kmem, unsigned long *pfn)
80 {
81 int rc;
82 sector_t block;
83
84 /* first, retrieve the sector number */
85 rc = __ext2_get_block(mapping->host, pgoff, create, &block);
86 if (rc)
87 return rc;
88
89 /* retrieve address of the target data */
90 rc = __inode_direct_access(mapping->host, block, kmem, pfn);
91 return rc;
92 }
93