xip: support non-struct page backed memory
[linux-2.6.git] / fs / ext2 / xip.c
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 "ext2.h"
15 #include "xip.h"
16
17 static inline int
18 __inode_direct_access(struct inode *inode, sector_t block,
19                       void **kaddr, unsigned long *pfn)
20 {
21         struct block_device *bdev = inode->i_sb->s_bdev;
22         struct block_device_operations *ops = bdev->bd_disk->fops;
23         sector_t sector;
24
25         sector = block * (PAGE_SIZE / 512); /* ext2 block to bdev sector */
26
27         BUG_ON(!ops->direct_access);
28         return ops->direct_access(bdev, sector, kaddr, pfn);
29 }
30
31 static inline int
32 __ext2_get_block(struct inode *inode, pgoff_t pgoff, int create,
33                    sector_t *result)
34 {
35         struct buffer_head tmp;
36         int rc;
37
38         memset(&tmp, 0, sizeof(struct buffer_head));
39         rc = ext2_get_block(inode, pgoff, &tmp, create);
40         *result = tmp.b_blocknr;
41
42         /* did we get a sparse block (hole in the file)? */
43         if (!tmp.b_blocknr && !rc) {
44                 BUG_ON(create);
45                 rc = -ENODATA;
46         }
47
48         return rc;
49 }
50
51 int
52 ext2_clear_xip_target(struct inode *inode, sector_t block)
53 {
54         void *kaddr;
55         unsigned long pfn;
56         int rc;
57
58         rc = __inode_direct_access(inode, block, &kaddr, &pfn);
59         if (!rc)
60                 clear_page(kaddr);
61         return rc;
62 }
63
64 void ext2_xip_verify_sb(struct super_block *sb)
65 {
66         struct ext2_sb_info *sbi = EXT2_SB(sb);
67
68         if ((sbi->s_mount_opt & EXT2_MOUNT_XIP) &&
69             !sb->s_bdev->bd_disk->fops->direct_access) {
70                 sbi->s_mount_opt &= (~EXT2_MOUNT_XIP);
71                 ext2_warning(sb, __FUNCTION__,
72                              "ignoring xip option - not supported by bdev");
73         }
74 }
75
76 int ext2_get_xip_mem(struct address_space *mapping, pgoff_t pgoff, int create,
77                                 void **kmem, unsigned long *pfn)
78 {
79         int rc;
80         sector_t block;
81
82         /* first, retrieve the sector number */
83         rc = __ext2_get_block(mapping->host, pgoff, create, &block);
84         if (rc)
85                 return rc;
86
87         /* retrieve address of the target data */
88         rc = __inode_direct_access(mapping->host, block, kmem, pfn);
89         return rc;
90 }