File: /usr/src/linux/fs/fat/file.c

1     /*
2      *  linux/fs/fat/file.c
3      *
4      *  Written 1992,1993 by Werner Almesberger
5      *
6      *  regular file handling primitives for fat-based filesystems
7      */
8     
9     #include <linux/sched.h>
10     #include <linux/locks.h>
11     #include <linux/fs.h>
12     #include <linux/msdos_fs.h>
13     #include <linux/errno.h>
14     #include <linux/fcntl.h>
15     #include <linux/stat.h>
16     #include <linux/string.h>
17     #include <linux/pagemap.h>
18     #include <linux/fat_cvf.h>
19     
20     #include <asm/uaccess.h>
21     #include <asm/system.h>
22     
23     #define PRINTK(x)
24     #define Printk(x) printk x
25     
26     struct file_operations fat_file_operations = {
27     	llseek:		generic_file_llseek,
28     	read:		fat_file_read,
29     	write:		fat_file_write,
30     	mmap:		generic_file_mmap,
31     	fsync:		file_fsync,
32     };
33     
34     struct inode_operations fat_file_inode_operations = {
35     	truncate:	fat_truncate,
36     	setattr:	fat_notify_change,
37     };
38     
39     ssize_t fat_file_read(
40     	struct file *filp,
41     	char *buf,
42     	size_t count,
43     	loff_t *ppos)
44     {
45     	struct inode *inode = filp->f_dentry->d_inode;
46     	return MSDOS_SB(inode->i_sb)->cvf_format
47     			->cvf_file_read(filp,buf,count,ppos);
48     }
49     
50     
51     int fat_get_block(struct inode *inode, long iblock, struct buffer_head *bh_result, int create)
52     {
53     	struct super_block *sb = inode->i_sb;
54     	unsigned long phys;
55     
56     	phys = fat_bmap(inode, iblock);
57     	if (phys) {
58     		bh_result->b_dev = inode->i_dev;
59     		bh_result->b_blocknr = phys;
60     		bh_result->b_state |= (1UL << BH_Mapped);
61     		return 0;
62     	}
63     	if (!create)
64     		return 0;
65     	if (iblock << sb->s_blocksize_bits != MSDOS_I(inode)->mmu_private) {
66     		BUG();
67     		return -EIO;
68     	}
69     	if (!(iblock % MSDOS_SB(inode->i_sb)->cluster_size)) {
70     		if (fat_add_cluster(inode) < 0)
71     			return -ENOSPC;
72     	}
73     	MSDOS_I(inode)->mmu_private += sb->s_blocksize;
74     	phys = fat_bmap(inode, iblock);
75     	if (!phys)
76     		BUG();
77     	bh_result->b_dev = inode->i_dev;
78     	bh_result->b_blocknr = phys;
79     	bh_result->b_state |= (1UL << BH_Mapped);
80     	bh_result->b_state |= (1UL << BH_New);
81     	return 0;
82     }
83     
84     ssize_t fat_file_write(
85     	struct file *filp,
86     	const char *buf,
87     	size_t count,
88     	loff_t *ppos)
89     {
90     	struct inode *inode = filp->f_dentry->d_inode;
91     	struct super_block *sb = inode->i_sb;
92     	return MSDOS_SB(sb)->cvf_format
93     			->cvf_file_write(filp,buf,count,ppos);
94     }
95     
96     ssize_t default_fat_file_write(
97     	struct file *filp,
98     	const char *buf,
99     	size_t count,
100     	loff_t *ppos)
101     {
102     	struct inode *inode = filp->f_dentry->d_inode;
103     	int retval;
104     
105     	retval = generic_file_write(filp, buf, count, ppos);
106     	if (retval > 0) {
107     		inode->i_mtime = inode->i_ctime = CURRENT_TIME;
108     		MSDOS_I(inode)->i_attrs |= ATTR_ARCH;
109     		mark_inode_dirty(inode);
110     	}
111     	return retval;
112     }
113     
114     void fat_truncate(struct inode *inode)
115     {
116     	struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
117     	int cluster;
118     
119     	/* Why no return value?  Surely the disk could fail... */
120     	if (IS_RDONLY (inode))
121     		return /* -EPERM */;
122     	if (IS_IMMUTABLE(inode))
123     		return /* -EPERM */;
124     	cluster = 1 << sbi->cluster_bits;
125     	/* 
126     	 * This protects against truncating a file bigger than it was then
127     	 * trying to write into the hole.
128     	 */
129     	if (MSDOS_I(inode)->mmu_private > inode->i_size)
130     		MSDOS_I(inode)->mmu_private = inode->i_size;
131     
132     	fat_free(inode, (inode->i_size + (cluster - 1)) >> sbi->cluster_bits);
133     	MSDOS_I(inode)->i_attrs |= ATTR_ARCH;
134     	inode->i_ctime = inode->i_mtime = CURRENT_TIME;
135     	mark_inode_dirty(inode);
136     }
137