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/blkdev.h>
13 #include "ext2.h"
14 #include "xip.h"
15
16 static inline int
__inode_direct_access(struct inode * inode,sector_t block,void ** kaddr,unsigned long * pfn)17 __inode_direct_access(struct inode *inode, sector_t block,
18 void **kaddr, unsigned long *pfn)
19 {
20 struct block_device *bdev = inode->i_sb->s_bdev;
21 const struct block_device_operations *ops = bdev->bd_disk->fops;
22 sector_t sector;
23
24 sector = block * (PAGE_SIZE / 512); /* ext2 block to bdev sector */
25
26 BUG_ON(!ops->direct_access);
27 return ops->direct_access(bdev, sector, kaddr, pfn);
28 }
29
30 static inline int
__ext2_get_block(struct inode * inode,pgoff_t pgoff,int create,sector_t * result)31 __ext2_get_block(struct inode *inode, pgoff_t pgoff, int create,
32 sector_t *result)
33 {
34 struct buffer_head tmp;
35 int rc;
36
37 memset(&tmp, 0, sizeof(struct buffer_head));
38 rc = ext2_get_block(inode, pgoff, &tmp, create);
39 *result = tmp.b_blocknr;
40
41 /* did we get a sparse block (hole in the file)? */
42 if (!tmp.b_blocknr && !rc) {
43 BUG_ON(create);
44 rc = -ENODATA;
45 }
46
47 return rc;
48 }
49
50 int
ext2_clear_xip_target(struct inode * inode,sector_t block)51 ext2_clear_xip_target(struct inode *inode, sector_t block)
52 {
53 void *kaddr;
54 unsigned long pfn;
55 int rc;
56
57 rc = __inode_direct_access(inode, block, &kaddr, &pfn);
58 if (!rc)
59 clear_page(kaddr);
60 return rc;
61 }
62
ext2_xip_verify_sb(struct super_block * sb)63 void ext2_xip_verify_sb(struct super_block *sb)
64 {
65 struct ext2_sb_info *sbi = EXT2_SB(sb);
66
67 if ((sbi->s_mount_opt & EXT2_MOUNT_XIP) &&
68 !sb->s_bdev->bd_disk->fops->direct_access) {
69 sbi->s_mount_opt &= (~EXT2_MOUNT_XIP);
70 ext2_msg(sb, KERN_WARNING,
71 "warning: ignoring xip option - "
72 "not supported by bdev");
73 }
74 }
75
ext2_get_xip_mem(struct address_space * mapping,pgoff_t pgoff,int create,void ** kmem,unsigned long * pfn)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 }
91