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[/] [or1k/] [trunk/] [rc203soc/] [sw/] [uClinux/] [fs/] [fat/] [file.c] - Blame information for rev 1765

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/*
 *  linux/fs/fat/file.c
 *
 *  Written 1992,1993 by Werner Almesberger
 *
 *  regular file handling primitives for fat-based filesystems
 */
 
#define ASC_LINUX_VERSION(V, P, S)      (((V) * 65536) + ((P) * 256) + (S))
#include <linux/version.h>
#include <linux/sched.h>
#include <linux/locks.h>
#include <linux/fs.h>
#include <linux/msdos_fs.h>
#include <linux/errno.h>
#include <linux/fcntl.h>
#include <linux/stat.h>
#include <linux/string.h>
#include <linux/pagemap.h>
 
#if LINUX_VERSION_CODE >= ASC_LINUX_VERSION(2,1,0)
#include <asm/uaccess.h>
#define FAT_COPY_TO_USER(uaddr, kaddr, len) copy_to_user(uaddr, kaddr, len)
#define FAT_COPY_FROM_USER(uaddr, kaddr, len) copy_from_user(uaddr, kaddr, len)
#define FAT_GET_USER(c, ptr) get_user((c), ptr)
#else
#include <asm/segment.h>
#define FAT_COPY_TO_USER(uaddr, kaddr, len) memcpy_tofs(uaddr, kaddr, len)
#define FAT_COPY_FROM_USER(uaddr, kaddr, len) memcpy_fromfs(uaddr, kaddr, len)
#define FAT_GET_USER(c, ptr) (c) = get_user(ptr)
#endif
#include <asm/system.h>
 
#include "msbuffer.h"
 
#define MIN(a,b) (((a) < (b)) ? (a) : (b))
#define MAX(a,b) (((a) > (b)) ? (a) : (b))
 
#define PRINTK(x)
#define Printk(x) printk x
 
static struct file_operations fat_file_operations = {
        NULL,                   /* lseek - default */
        fat_file_read,          /* read */
        fat_file_write,         /* write */
        NULL,                   /* readdir - bad */
        NULL,                   /* select v2.0.x/poll v2.1.x - default */
        NULL,                   /* ioctl - default */
        generic_file_mmap,      /* mmap */
        NULL,                   /* no special open is needed */
        NULL,                   /* release */
        file_fsync              /* fsync */
};
 
struct inode_operations fat_file_inode_operations = {
        &fat_file_operations,   /* default file operations */
        NULL,                   /* create */
        NULL,                   /* lookup */
        NULL,                   /* link */
        NULL,                   /* unlink */
        NULL,                   /* symlink */
        NULL,                   /* mkdir */
        NULL,                   /* rmdir */
        NULL,                   /* mknod */
        NULL,                   /* rename */
        NULL,                   /* readlink */
        NULL,                   /* follow_link */
        generic_readpage,       /* readpage */
        NULL,                   /* writepage */
        fat_bmap,               /* bmap */
        fat_truncate,           /* truncate */
        NULL,                   /* permission */
        NULL                    /* smap */
};
/* #Specification: msdos / special devices / mmap
        Mmapping does work because a special mmap is provide in that case.
        Note that it is much less efficient than the generic_file_mmap normally
        used since it allocate extra buffer. generic_file_mmap is used for
        normal device (512 bytes hardware sectors).
*/
static struct file_operations fat_file_operations_1024 = {
        NULL,                   /* lseek - default */
        fat_file_read,          /* read */
        fat_file_write,         /* write */
        NULL,                   /* readdir - bad */
        NULL,                   /* select v2.0.x/poll v2.1.x - default */
        NULL,                   /* ioctl - default */
        fat_mmap,               /* mmap */
        NULL,                   /* no special open is needed */
        NULL,                   /* release */
        file_fsync              /* fsync */
};
 
/* #Specification: msdos / special devices / swap file
        Swap file can't work on special devices with a large sector
        size (1024 bytes hard sector). Those devices have a weird
        MsDOS filesystem layout. Generally a single hardware sector
        may contain 2 unrelated logical sector. This mean that there is
        no easy way to do a mapping between disk sector of a file and virtual
        memory. So swap file is difficult (not available right now)
        on those devices. Off course, Ext2 does not have this problem.
*/
struct inode_operations fat_file_inode_operations_1024 = {
        &fat_file_operations_1024,      /* default file operations */
        NULL,                   /* create */
        NULL,                   /* lookup */
        NULL,                   /* link */
        NULL,                   /* unlink */
        NULL,                   /* symlink */
        NULL,                   /* mkdir */
        NULL,                   /* rmdir */
        NULL,                   /* mknod */
        NULL,                   /* rename */
        NULL,                   /* readlink */
        NULL,                   /* follow_link */
        NULL,                   /* readpage */
        NULL,                   /* writepage */
        NULL,                   /* bmap */
        fat_truncate,           /* truncate */
        NULL,                   /* permission */
        NULL                    /* smap */
};
 
#define MSDOS_PREFETCH  32
struct fat_pre {
        int file_sector;/* Next sector to read in the prefetch table */
                        /* This is relative to the file, not the disk */
        struct buffer_head *bhlist[MSDOS_PREFETCH];     /* All buffers needed */
        int nblist;     /* Number of buffers in bhlist */
        int nolist;     /* index in bhlist */
};
/*
        Order the prefetch of more sectors.
*/
static void fat_prefetch (
        struct inode *inode,
        struct fat_pre *pre,
        int nb)         /* How many must we prefetch at once */
{
        struct super_block *sb = inode->i_sb;
        struct buffer_head *bhreq[MSDOS_PREFETCH];      /* Buffers not */
                                                        /* already read */
        int nbreq = 0;                   /* Number of buffers in bhreq */
        int i;
        for (i=0; i<nb; i++){
                int sector = fat_smap(inode,pre->file_sector);
                if (sector != 0){
                        struct buffer_head *bh;
                        PRINTK (("fsector2 %d -> %d\n",pre->file_sector-1,sector));
                        pre->file_sector++;
                        bh = fat_getblk(sb, sector);
                        if (bh == NULL) break;
                        pre->bhlist[pre->nblist++] = bh;
                        if (!fat_is_uptodate(sb,bh))
                                bhreq[nbreq++] = bh;
                }else{
                        break;
                }
        }
        if (nbreq > 0) fat_ll_rw_block (sb,READ,nbreq,bhreq);
        for (i=pre->nblist; i<MSDOS_PREFETCH; i++) pre->bhlist[i] = NULL;
}
 
/*
        Read a file into user space
*/
#if LINUX_VERSION_CODE >= ASC_LINUX_VERSION(2,1,0)
long fat_file_read(struct inode *inode,struct file *filp,char *buf,
                   unsigned long count)
#else
int fat_file_read(struct inode *inode,struct file *filp,char *buf,int count)
#endif
{
        struct super_block *sb = inode->i_sb;
        char *start = buf;
        char *end   = buf + count;
        int i;
        int left_in_file;
        struct fat_pre pre;
 
 
        if (!inode) {
                printk("fat_file_read: inode = NULL\n");
                return -EINVAL;
        }
        /* S_ISLNK allows for UMSDOS. Should never happen for normal MSDOS */
        if (!S_ISREG(inode->i_mode) && !S_ISLNK(inode->i_mode)) {
                printk("fat_file_read: mode = %07o\n",inode->i_mode);
                return -EINVAL;
        }
#if LINUX_VERSION_CODE >= ASC_LINUX_VERSION(2,1,0)
        if (filp->f_pos >= inode->i_size || count == 0) return 0;
#else
        if (filp->f_pos >= inode->i_size || count <= 0) return 0;
#endif
        /*
                Tell the buffer cache which block we expect to read in advance
                Since we are limited with the stack, we preread only MSDOS_PREFETCH
                because we have to keep the result into the local
                arrays pre.bhlist and bhreq.
 
                Each time we process one block in bhlist, we replace
                it by a new prefetch block if needed.
        */
        PRINTK (("#### ino %ld pos %ld size %ld count %d\n",inode->i_ino,filp->f_pos,inode->i_size,count));
        {
                /*
                        We must prefetch complete block, so we must
                        take in account the offset in the first block.
                */
                int count_max = (filp->f_pos & (SECTOR_SIZE-1)) + count;
                int   to_reada; /* How many block to read all at once */
                pre.file_sector = filp->f_pos >> SECTOR_BITS;
                to_reada = count_max / SECTOR_SIZE;
                if (count_max & (SECTOR_SIZE-1)) to_reada++;
                if (filp->f_reada || !MSDOS_I(inode)->i_binary){
                        /* Doing a read ahead on ascii file make sure we always */
                        /* pre read enough, since we don't know how many blocks */
                        /* we really need */
                        int ahead = read_ahead[MAJOR(inode->i_dev)];
                        PRINTK (("to_reada %d ahead %d\n",to_reada,ahead));
                        if (ahead == 0) ahead = 8;
                        to_reada += ahead;
                }
                if (to_reada > MSDOS_PREFETCH) to_reada = MSDOS_PREFETCH;
                pre.nblist = 0;
                fat_prefetch (inode,&pre,to_reada);
        }
        pre.nolist = 0;
        PRINTK (("count %d ahead %d nblist %d\n",count,read_ahead[MAJOR(inode->i_dev)],pre.nblist));
        while ((left_in_file = inode->i_size - filp->f_pos) > 0
                && buf < end){
                struct buffer_head *bh = pre.bhlist[pre.nolist];
                char *data;
                int size,offset;
                if (bh == NULL) break;
                pre.bhlist[pre.nolist] = NULL;
                pre.nolist++;
                if (pre.nolist == MSDOS_PREFETCH/2){
                        memcpy (pre.bhlist,pre.bhlist+MSDOS_PREFETCH/2
                                ,(MSDOS_PREFETCH/2)*sizeof(pre.bhlist[0]));
                        pre.nblist -= MSDOS_PREFETCH/2;
                        fat_prefetch (inode,&pre,MSDOS_PREFETCH/2);
                        pre.nolist = 0;
                }
                PRINTK (("file_read pos %ld nblist %d %d %d\n",filp->f_pos,pre.nblist,pre.fetched,count));
                wait_on_buffer(bh);
                if (!fat_is_uptodate(sb,bh)){
                        /* read error  ? */
                        fat_brelse (sb, bh);
                        break;
                }
                offset = filp->f_pos & (SECTOR_SIZE-1);
                data = bh->b_data + offset;
                size = MIN(SECTOR_SIZE-offset,left_in_file);
                if (MSDOS_I(inode)->i_binary) {
                        size = MIN(size,end-buf);
                        FAT_COPY_TO_USER(buf,data,size);
                        buf += size;
                        filp->f_pos += size;
                }else{
                        for (; size && buf < end; size--) {
                                char ch = *data++;
                                filp->f_pos++;
                                if (ch == 26){
                                        filp->f_pos = inode->i_size;
                                        break;
                                }else if (ch != '\r'){
                                        put_user(ch,buf++);
                                }
                        }
                }
                fat_brelse(sb, bh);
        }
        PRINTK (("--- %d -> %d\n",count,(int)(buf-start)));
        for (i=0; i<pre.nblist; i++)
                fat_brelse (sb, pre.bhlist[i]);
        if (start == buf)
                return -EIO;
        if (!IS_RDONLY(inode))
                inode->i_atime = CURRENT_TIME;
        filp->f_reada = 1;      /* Will be reset if a lseek is done */
        return buf-start;
}
 
/*
        Write to a file either from user space
*/
#if LINUX_VERSION_CODE >= ASC_LINUX_VERSION(2,1,0)
long fat_file_write(struct inode *inode,struct file *filp,const char *buf,
                    unsigned long count)
#else
int fat_file_write(struct inode *inode,struct file *filp,const char *buf,int count)
#endif
{
        struct super_block *sb = inode->i_sb;
        int sector,offset,size,left,written;
        int error,carry;
        const char *start;
        char *to,ch;
        struct buffer_head *bh;
        int binary_mode = MSDOS_I(inode)->i_binary;
 
        if (!inode) {
                printk("fat_file_write: inode = NULL\n");
                return -EINVAL;
        }
        /* S_ISLNK allows for UMSDOS. Should never happen for normal MSDOS */
        if (!S_ISREG(inode->i_mode) && !S_ISLNK(inode->i_mode)) {
                printk("fat_file_write: mode = %07o\n",inode->i_mode);
                return -EINVAL;
        }
        /* system files may be immutable */
        if (IS_IMMUTABLE(inode))
                return -EPERM;
/*
 * ok, append may not work when many processes are writing at the same time
 * but so what. That way leads to madness anyway.
 */
        if (filp->f_flags & O_APPEND)
                filp->f_pos = inode->i_size;
#if LINUX_VERSION_CODE >= ASC_LINUX_VERSION(2,1,0)
        if (count == 0) return 0;
#else
        if (count <= 0) return 0;
#endif
        if (filp->f_pos + count > 0x7FFFFFFFL) {
                count = 0x7FFFFFFFL - filp->f_pos;
                if (!count)
                        return -EFBIG;
        }
 
        error = carry = 0;
        for (start = buf; count || carry; count -= size) {
                while (!(sector = fat_smap(inode,filp->f_pos >> SECTOR_BITS)))
                        if ((error = fat_add_cluster(inode)) < 0) break;
                if (error) {
                        fat_truncate(inode);
                        break;
                }
                offset = filp->f_pos & (SECTOR_SIZE-1);
                size = MIN(SECTOR_SIZE-offset,MAX(carry,count));
                if (binary_mode
                        && offset == 0
                        && (size == SECTOR_SIZE
                                || filp->f_pos + size >= inode->i_size)){
                        /* No need to read the block first since we will */
                        /* completely overwrite it */
                        /* or at least write past the end of file */
                        if (!(bh = fat_getblk(sb,sector))){
                                error = -EIO;
                                break;
                        }
                } else if (!(bh = fat_bread(sb,sector))) {
                        error = -EIO;
                        break;
                }
                if (binary_mode) {
                        FAT_COPY_FROM_USER(bh->b_data+offset,buf,written = size);
                        buf += size;
                } else {
                        written = left = SECTOR_SIZE-offset;
                        to = (char *) bh->b_data+(filp->f_pos & (SECTOR_SIZE-1));
                        if (carry) {
                                *to++ = '\n';
                                left--;
                                carry = 0;
                        }
                        for (size = 0; size < count && left; size++) {
                                FAT_GET_USER(ch, buf++);
                                if (ch == '\n') {
                                        *to++ = '\r';
                                        left--;
                                }
                                if (!left) carry = 1;
                                else {
                                        *to++ = ch;
                                        left--;
                                }
                        }
                        written -= left;
                }
                update_vm_cache(inode, filp->f_pos, bh->b_data + (filp->f_pos & (SECTOR_SIZE-1)), written);
                filp->f_pos += written;
                if (filp->f_pos > inode->i_size) {
                        inode->i_size = filp->f_pos;
                        inode->i_dirt = 1;
                }
                fat_set_uptodate(sb, bh, 1);
                fat_mark_buffer_dirty(sb, bh, 0);
                fat_brelse(sb, bh);
        }
        if (start == buf)
                return error;
        inode->i_mtime = inode->i_ctime = CURRENT_TIME;
        MSDOS_I(inode)->i_attrs |= ATTR_ARCH;
        inode->i_dirt = 1;
        return buf-start;
}
 
void fat_truncate(struct inode *inode)
{
        int cluster;
 
        /* Why no return value?  Surely the disk could fail... */
        if (IS_IMMUTABLE(inode))
                return /* -EPERM */;
        cluster = SECTOR_SIZE*MSDOS_SB(inode->i_sb)->cluster_size;
        (void) fat_free(inode,(inode->i_size+(cluster-1))/cluster);
        MSDOS_I(inode)->i_attrs |= ATTR_ARCH;
        inode->i_dirt = 1;
}

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[/] [or1k/] [trunk/] [rc203soc/] [sw/] [uClinux/] [fs/] [fat/] [file.c] - Blame information for rev 1765

Line No.	Rev	Author	Line
1	1628	jcastillo	`/*`
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			`#define ASC_LINUX_VERSION(V, P, S) (((V) * 65536) + ((P) * 256) + (S))`
10			`#include <linux/version.h>`
11			`#include <linux/sched.h>`
12			`#include <linux/locks.h>`
13			`#include <linux/fs.h>`
14			`#include <linux/msdos_fs.h>`
15			`#include <linux/errno.h>`
16			`#include <linux/fcntl.h>`
17			`#include <linux/stat.h>`
18			`#include <linux/string.h>`
19			`#include <linux/pagemap.h>`
20
21			`#if LINUX_VERSION_CODE >= ASC_LINUX_VERSION(2,1,0)`
22			`#include <asm/uaccess.h>`
23			`#define FAT_COPY_TO_USER(uaddr, kaddr, len) copy_to_user(uaddr, kaddr, len)`
24			`#define FAT_COPY_FROM_USER(uaddr, kaddr, len) copy_from_user(uaddr, kaddr, len)`
25			`#define FAT_GET_USER(c, ptr) get_user((c), ptr)`
26			`#else`
27			`#include <asm/segment.h>`
28			`#define FAT_COPY_TO_USER(uaddr, kaddr, len) memcpy_tofs(uaddr, kaddr, len)`
29			`#define FAT_COPY_FROM_USER(uaddr, kaddr, len) memcpy_fromfs(uaddr, kaddr, len)`
30			`#define FAT_GET_USER(c, ptr) (c) = get_user(ptr)`
31			`#endif`
32			`#include <asm/system.h>`
33
34			`#include "msbuffer.h"`
35
36			`#define MIN(a,b) (((a) < (b)) ? (a) : (b))`
37			`#define MAX(a,b) (((a) > (b)) ? (a) : (b))`
38
39			`#define PRINTK(x)`
40			`#define Printk(x) printk x`
41
42			`static struct file_operations fat_file_operations = {`
43			`NULL, /* lseek - default */`
44			`fat_file_read, /* read */`
45			`fat_file_write, /* write */`
46			`NULL, /* readdir - bad */`
47			`NULL, /* select v2.0.x/poll v2.1.x - default */`
48			`NULL, /* ioctl - default */`
49			`generic_file_mmap, /* mmap */`
50			`NULL, /* no special open is needed */`
51			`NULL, /* release */`
52			`file_fsync /* fsync */`
53			`};`
54
55			`struct inode_operations fat_file_inode_operations = {`
56			`&fat_file_operations, /* default file operations */`
57			`NULL, /* create */`
58			`NULL, /* lookup */`
59			`NULL, /* link */`
60			`NULL, /* unlink */`
61			`NULL, /* symlink */`
62			`NULL, /* mkdir */`
63			`NULL, /* rmdir */`
64			`NULL, /* mknod */`
65			`NULL, /* rename */`
66			`NULL, /* readlink */`
67			`NULL, /* follow_link */`
68			`generic_readpage, /* readpage */`
69			`NULL, /* writepage */`
70			`fat_bmap, /* bmap */`
71			`fat_truncate, /* truncate */`
72			`NULL, /* permission */`
73			`NULL /* smap */`
74			`};`
75			`/* #Specification: msdos / special devices / mmap`
76			`Mmapping does work because a special mmap is provide in that case.`
77			`Note that it is much less efficient than the generic_file_mmap normally`
78			`used since it allocate extra buffer. generic_file_mmap is used for`
79			`normal device (512 bytes hardware sectors).`
80			`*/`
81			`static struct file_operations fat_file_operations_1024 = {`
82			`NULL, /* lseek - default */`
83			`fat_file_read, /* read */`
84			`fat_file_write, /* write */`
85			`NULL, /* readdir - bad */`
86			`NULL, /* select v2.0.x/poll v2.1.x - default */`
87			`NULL, /* ioctl - default */`
88			`fat_mmap, /* mmap */`
89			`NULL, /* no special open is needed */`
90			`NULL, /* release */`
91			`file_fsync /* fsync */`
92			`};`
93
94			`/* #Specification: msdos / special devices / swap file`
95			`Swap file can't work on special devices with a large sector`
96			`size (1024 bytes hard sector). Those devices have a weird`
97			`MsDOS filesystem layout. Generally a single hardware sector`
98			`may contain 2 unrelated logical sector. This mean that there is`
99			`no easy way to do a mapping between disk sector of a file and virtual`
100			`memory. So swap file is difficult (not available right now)`
101			`on those devices. Off course, Ext2 does not have this problem.`
102			`*/`
103			`struct inode_operations fat_file_inode_operations_1024 = {`
104			`&fat_file_operations_1024, /* default file operations */`
105			`NULL, /* create */`
106			`NULL, /* lookup */`
107			`NULL, /* link */`
108			`NULL, /* unlink */`
109			`NULL, /* symlink */`
110			`NULL, /* mkdir */`
111			`NULL, /* rmdir */`
112			`NULL, /* mknod */`
113			`NULL, /* rename */`
114			`NULL, /* readlink */`
115			`NULL, /* follow_link */`
116			`NULL, /* readpage */`
117			`NULL, /* writepage */`
118			`NULL, /* bmap */`
119			`fat_truncate, /* truncate */`
120			`NULL, /* permission */`
121			`NULL /* smap */`
122			`};`
123
124			`#define MSDOS_PREFETCH 32`
125			`struct fat_pre {`
126			`int file_sector;/* Next sector to read in the prefetch table */`
127			`/* This is relative to the file, not the disk */`
128			`struct buffer_head bhlist[MSDOS_PREFETCH]; / All buffers needed */`
129			`int nblist; /* Number of buffers in bhlist */`
130			`int nolist; /* index in bhlist */`
131			`};`
132			`/*`
133			`Order the prefetch of more sectors.`
134			`*/`
135			`static void fat_prefetch (`
136			`struct inode *inode,`
137			`struct fat_pre *pre,`
138			`int nb) /* How many must we prefetch at once */`
139			`{`
140			`struct super_block *sb = inode->i_sb;`
141			`struct buffer_head bhreq[MSDOS_PREFETCH]; / Buffers not */`
142			`/* already read */`
143			`int nbreq = 0; /* Number of buffers in bhreq */`
144			`int i;`
145			`for (i=0; i<nb; i++){`
146			`int sector = fat_smap(inode,pre->file_sector);`
147			`if (sector != 0){`
148			`struct buffer_head *bh;`
149			`PRINTK (("fsector2 %d -> %d\n",pre->file_sector-1,sector));`
150			`pre->file_sector++;`
151			`bh = fat_getblk(sb, sector);`
152			`if (bh == NULL) break;`
153			`pre->bhlist[pre->nblist++] = bh;`
154			`if (!fat_is_uptodate(sb,bh))`
155			`bhreq[nbreq++] = bh;`
156			`}else{`
157			`break;`
158			`}`
159			`}`
160			`if (nbreq > 0) fat_ll_rw_block (sb,READ,nbreq,bhreq);`
161			`for (i=pre->nblist; i<MSDOS_PREFETCH; i++) pre->bhlist[i] = NULL;`
162			`}`
163
164			`/*`
165			`Read a file into user space`
166			`*/`
167			`#if LINUX_VERSION_CODE >= ASC_LINUX_VERSION(2,1,0)`
168			`long fat_file_read(struct inode inode,struct file filp,char *buf,`
169			`unsigned long count)`
170			`#else`
171			`int fat_file_read(struct inode inode,struct file filp,char *buf,int count)`
172			`#endif`
173			`{`
174			`struct super_block *sb = inode->i_sb;`
175			`char *start = buf;`
176			`char *end = buf + count;`
177			`int i;`
178			`int left_in_file;`
179			`struct fat_pre pre;`
180
181
182			`if (!inode) {`
183			`printk("fat_file_read: inode = NULL\n");`
184			`return -EINVAL;`
185			`}`
186			`/* S_ISLNK allows for UMSDOS. Should never happen for normal MSDOS */`
187			`if (!S_ISREG(inode->i_mode) && !S_ISLNK(inode->i_mode)) {`
188			`printk("fat_file_read: mode = %07o\n",inode->i_mode);`
189			`return -EINVAL;`
190			`}`
191			`#if LINUX_VERSION_CODE >= ASC_LINUX_VERSION(2,1,0)`
192			`if (filp->f_pos >= inode->i_size \|\| count == 0) return 0;`
193			`#else`
194			`if (filp->f_pos >= inode->i_size \|\| count <= 0) return 0;`
195			`#endif`
196			`/*`
197			`Tell the buffer cache which block we expect to read in advance`
198			`Since we are limited with the stack, we preread only MSDOS_PREFETCH`
199			`because we have to keep the result into the local`
200			`arrays pre.bhlist and bhreq.`
201
202			`Each time we process one block in bhlist, we replace`
203			`it by a new prefetch block if needed.`
204			`*/`
205			`PRINTK (("#### ino %ld pos %ld size %ld count %d\n",inode->i_ino,filp->f_pos,inode->i_size,count));`
206			`{`
207			`/*`
208			`We must prefetch complete block, so we must`
209			`take in account the offset in the first block.`
210			`*/`
211			`int count_max = (filp->f_pos & (SECTOR_SIZE-1)) + count;`
212			`int to_reada; /* How many block to read all at once */`
213			`pre.file_sector = filp->f_pos >> SECTOR_BITS;`
214			`to_reada = count_max / SECTOR_SIZE;`
215			`if (count_max & (SECTOR_SIZE-1)) to_reada++;`
216			`if (filp->f_reada \|\| !MSDOS_I(inode)->i_binary){`
217			`/* Doing a read ahead on ascii file make sure we always */`
218			`/* pre read enough, since we don't know how many blocks */`
219			`/* we really need */`
220			`int ahead = read_ahead[MAJOR(inode->i_dev)];`
221			`PRINTK (("to_reada %d ahead %d\n",to_reada,ahead));`
222			`if (ahead == 0) ahead = 8;`
223			`to_reada += ahead;`
224			`}`
225			`if (to_reada > MSDOS_PREFETCH) to_reada = MSDOS_PREFETCH;`
226			`pre.nblist = 0;`
227			`fat_prefetch (inode,&pre,to_reada);`
228			`}`
229			`pre.nolist = 0;`
230			`PRINTK (("count %d ahead %d nblist %d\n",count,read_ahead[MAJOR(inode->i_dev)],pre.nblist));`
231			`while ((left_in_file = inode->i_size - filp->f_pos) > 0`
232			`&& buf < end){`
233			`struct buffer_head *bh = pre.bhlist[pre.nolist];`
234			`char *data;`
235			`int size,offset;`
236			`if (bh == NULL) break;`
237			`pre.bhlist[pre.nolist] = NULL;`
238			`pre.nolist++;`
239			`if (pre.nolist == MSDOS_PREFETCH/2){`
240			`memcpy (pre.bhlist,pre.bhlist+MSDOS_PREFETCH/2`
241			`,(MSDOS_PREFETCH/2)*sizeof(pre.bhlist[0]));`
242			`pre.nblist -= MSDOS_PREFETCH/2;`
243			`fat_prefetch (inode,&pre,MSDOS_PREFETCH/2);`
244			`pre.nolist = 0;`
245			`}`
246			`PRINTK (("file_read pos %ld nblist %d %d %d\n",filp->f_pos,pre.nblist,pre.fetched,count));`
247			`wait_on_buffer(bh);`
248			`if (!fat_is_uptodate(sb,bh)){`
249			`/* read error ? */`
250			`fat_brelse (sb, bh);`
251			`break;`
252			`}`
253			`offset = filp->f_pos & (SECTOR_SIZE-1);`
254			`data = bh->b_data + offset;`
255			`size = MIN(SECTOR_SIZE-offset,left_in_file);`
256			`if (MSDOS_I(inode)->i_binary) {`
257			`size = MIN(size,end-buf);`
258			`FAT_COPY_TO_USER(buf,data,size);`
259			`buf += size;`
260			`filp->f_pos += size;`
261			`}else{`
262			`for (; size && buf < end; size--) {`
263			`char ch = *data++;`
264			`filp->f_pos++;`
265			`if (ch == 26){`
266			`filp->f_pos = inode->i_size;`
267			`break;`
268			`}else if (ch != '\r'){`
269			`put_user(ch,buf++);`
270			`}`
271			`}`
272			`}`
273			`fat_brelse(sb, bh);`
274			`}`
275			`PRINTK (("--- %d -> %d\n",count,(int)(buf-start)));`
276			`for (i=0; i<pre.nblist; i++)`
277			`fat_brelse (sb, pre.bhlist[i]);`
278			`if (start == buf)`
279			`return -EIO;`
280			`if (!IS_RDONLY(inode))`
281			`inode->i_atime = CURRENT_TIME;`
282			`filp->f_reada = 1; /* Will be reset if a lseek is done */`
283			`return buf-start;`
284			`}`
285
286			`/*`
287			`Write to a file either from user space`
288			`*/`
289			`#if LINUX_VERSION_CODE >= ASC_LINUX_VERSION(2,1,0)`
290			`long fat_file_write(struct inode inode,struct file filp,const char *buf,`
291			`unsigned long count)`
292			`#else`
293			`int fat_file_write(struct inode inode,struct file filp,const char *buf,int count)`
294			`#endif`
295			`{`
296			`struct super_block *sb = inode->i_sb;`
297			`int sector,offset,size,left,written;`
298			`int error,carry;`
299			`const char *start;`
300			`char *to,ch;`
301			`struct buffer_head *bh;`
302			`int binary_mode = MSDOS_I(inode)->i_binary;`
303
304			`if (!inode) {`
305			`printk("fat_file_write: inode = NULL\n");`
306			`return -EINVAL;`
307			`}`
308			`/* S_ISLNK allows for UMSDOS. Should never happen for normal MSDOS */`
309			`if (!S_ISREG(inode->i_mode) && !S_ISLNK(inode->i_mode)) {`
310			`printk("fat_file_write: mode = %07o\n",inode->i_mode);`
311			`return -EINVAL;`
312			`}`
313			`/* system files may be immutable */`
314			`if (IS_IMMUTABLE(inode))`
315			`return -EPERM;`
316			`/*`
317			`* ok, append may not work when many processes are writing at the same time`
318			`* but so what. That way leads to madness anyway.`
319			`*/`
320			`if (filp->f_flags & O_APPEND)`
321			`filp->f_pos = inode->i_size;`
322			`#if LINUX_VERSION_CODE >= ASC_LINUX_VERSION(2,1,0)`
323			`if (count == 0) return 0;`
324			`#else`
325			`if (count <= 0) return 0;`
326			`#endif`
327			`if (filp->f_pos + count > 0x7FFFFFFFL) {`
328			`count = 0x7FFFFFFFL - filp->f_pos;`
329			`if (!count)`
330			`return -EFBIG;`
331			`}`
332
333			`error = carry = 0;`
334			`for (start = buf; count \|\| carry; count -= size) {`
335			`while (!(sector = fat_smap(inode,filp->f_pos >> SECTOR_BITS)))`
336			`if ((error = fat_add_cluster(inode)) < 0) break;`
337			`if (error) {`
338			`fat_truncate(inode);`
339			`break;`
340			`}`
341			`offset = filp->f_pos & (SECTOR_SIZE-1);`
342			`size = MIN(SECTOR_SIZE-offset,MAX(carry,count));`
343			`if (binary_mode`
344			`&& offset == 0`
345			`&& (size == SECTOR_SIZE`
346			`\|\| filp->f_pos + size >= inode->i_size)){`
347			`/* No need to read the block first since we will */`
348			`/* completely overwrite it */`
349			`/* or at least write past the end of file */`
350			`if (!(bh = fat_getblk(sb,sector))){`
351			`error = -EIO;`
352			`break;`
353			`}`
354			`} else if (!(bh = fat_bread(sb,sector))) {`
355			`error = -EIO;`
356			`break;`
357			`}`
358			`if (binary_mode) {`
359			`FAT_COPY_FROM_USER(bh->b_data+offset,buf,written = size);`
360			`buf += size;`
361			`} else {`
362			`written = left = SECTOR_SIZE-offset;`
363			`to = (char *) bh->b_data+(filp->f_pos & (SECTOR_SIZE-1));`
364			`if (carry) {`
365			`*to++ = '\n';`
366			`left--;`
367			`carry = 0;`
368			`}`
369			`for (size = 0; size < count && left; size++) {`
370			`FAT_GET_USER(ch, buf++);`
371			`if (ch == '\n') {`
372			`*to++ = '\r';`
373			`left--;`
374			`}`
375			`if (!left) carry = 1;`
376			`else {`
377			`*to++ = ch;`
378			`left--;`
379			`}`
380			`}`
381			`written -= left;`
382			`}`
383			`update_vm_cache(inode, filp->f_pos, bh->b_data + (filp->f_pos & (SECTOR_SIZE-1)), written);`
384			`filp->f_pos += written;`
385			`if (filp->f_pos > inode->i_size) {`
386			`inode->i_size = filp->f_pos;`
387			`inode->i_dirt = 1;`
388			`}`
389			`fat_set_uptodate(sb, bh, 1);`
390			`fat_mark_buffer_dirty(sb, bh, 0);`
391			`fat_brelse(sb, bh);`
392			`}`
393			`if (start == buf)`
394			`return error;`
395			`inode->i_mtime = inode->i_ctime = CURRENT_TIME;`
396			`MSDOS_I(inode)->i_attrs \|= ATTR_ARCH;`
397			`inode->i_dirt = 1;`
398			`return buf-start;`
399			`}`
400
401			`void fat_truncate(struct inode *inode)`
402			`{`
403			`int cluster;`
404
405			`/* Why no return value? Surely the disk could fail... */`
406			`if (IS_IMMUTABLE(inode))`
407			`return /* -EPERM */;`
408			`cluster = SECTOR_SIZE*MSDOS_SB(inode->i_sb)->cluster_size;`
409			`(void) fat_free(inode,(inode->i_size+(cluster-1))/cluster);`
410			`MSDOS_I(inode)->i_attrs \|= ATTR_ARCH;`
411			`inode->i_dirt = 1;`
412			`}`