fs/ext/file.c

/* */
This source file includes following definitions.
wait_on_buffer
ext_file_read
ext_file_write
   1 /*
   2  *  linux/fs/ext/file.c
   3  *
   4  *  Copyright (C) 1992 Remy Card (card@masi.ibp.fr)
   5  *
   6  *  from
   7  *
   8  *  linux/fs/minix/file.c
   9  *
  10  *  Copyright (C) 1991, 1992 Linus Torvalds
  11  *
  12  *  ext regular file handling primitives
  13  */
  14 
  15 #include <asm/segment.h>
  16 #include <asm/system.h>
  17 
  18 #include <linux/sched.h>
  19 #include <linux/ext_fs.h>
  20 #include <linux/kernel.h>
  21 #include <linux/errno.h>
  22 #include <linux/fcntl.h>
  23 #include <linux/stat.h>
  24 
  25 #define NBUF    16
  26 
  27 #define MIN(a,b) (((a)<(b))?(a):(b))
  28 #define MAX(a,b) (((a)>(b))?(a):(b))
  29 
  30 #include <linux/fs.h>
  31 #include <linux/ext_fs.h>
  32 
  33 static inline void wait_on_buffer(struct buffer_head * bh)
     /*  */
  34 {
  35         cli();
  36         while (bh->b_lock)
  37                 sleep_on(&bh->b_wait);
  38         sti();
  39 }
  40 
  41 static int ext_file_read(struct inode *, struct file *, char *, int);
  42 static int ext_file_write(struct inode *, struct file *, char *, int);
  43 
  44 /*
  45  * We have mostly NULL's here: the current defaults are ok for
  46  * the ext filesystem.
  47  */
  48 static struct file_operations ext_file_operations = {
  49         NULL,                   /* lseek - default */
  50         ext_file_read,  /* read */
  51         ext_file_write, /* write */
  52         NULL,                   /* readdir - bad */
  53         NULL,                   /* select - default */
  54         NULL,                   /* ioctl - default */
  55         NULL,                   /* no special open is needed */
  56         NULL                    /* release */
  57 };
  58 
  59 struct inode_operations ext_file_inode_operations = {
  60         &ext_file_operations,   /* default file operations */
  61         NULL,                   /* create */
  62         NULL,                   /* lookup */
  63         NULL,                   /* link */
  64         NULL,                   /* unlink */
  65         NULL,                   /* symlink */
  66         NULL,                   /* mkdir */
  67         NULL,                   /* rmdir */
  68         NULL,                   /* mknod */
  69         NULL,                   /* rename */
  70         NULL,                   /* readlink */
  71         NULL,                   /* follow_link */
  72         ext_bmap,               /* bmap */
  73         ext_truncate            /* truncate */
  74 };
  75 
  76 static int ext_file_read(struct inode * inode, struct file * filp, char * buf, int count)
     /*  */
  77 {
  78         int read,left,chars;
  79         int block, blocks, offset;
  80         struct buffer_head ** bhb, ** bhe;
  81         struct buffer_head * buflist[NBUF];
  82 
  83         if (!inode) {
  84                 printk("ext_file_read: inode = NULL\n");
  85                 return -EINVAL;
  86         }
  87         if (!(S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode))) {
  88                 printk("ext_file_read: mode = %07o\n",inode->i_mode);
  89                 return -EINVAL;
  90         }
  91         if (filp->f_pos > inode->i_size)
  92                 left = 0;
  93         else
  94                 left = inode->i_size - filp->f_pos;
  95         if (left > count)
  96                 left = count;
  97         if (left <= 0)
  98                 return 0;
  99         read = 0;
 100         block = filp->f_pos >> BLOCK_SIZE_BITS;
 101         offset = filp->f_pos & (BLOCK_SIZE-1);
 102         blocks = (left + offset + BLOCK_SIZE - 1) / BLOCK_SIZE;
 103         bhb = bhe = buflist;
 104         do {
 105                 if (blocks) {
 106                         --blocks;
 107                         *bhb = ext_getblk(inode,block++,0);
 108                         if (*bhb && !(*bhb)->b_uptodate)
 109                                 ll_rw_block(READ,*bhb);
 110 
 111                         if (++bhb == &buflist[NBUF])
 112                                 bhb = buflist;
 113 
 114                         if (bhb != bhe)
 115                                 continue;
 116                 }
 117                 if (*bhe) {
 118                         wait_on_buffer(*bhe);
 119                         if (!(*bhe)->b_uptodate) {
 120                                 do {
 121                                         brelse(*bhe);
 122                                         if (++bhe == &buflist[NBUF])
 123                                                 bhe = buflist;
 124                                 } while (bhe != bhb);
 125                                 break;
 126                         }
 127                 }
 128 
 129                 if (left < BLOCK_SIZE - offset)
 130                         chars = left;
 131                 else
 132                         chars = BLOCK_SIZE - offset;
 133                 filp->f_pos += chars;
 134                 left -= chars;
 135                 read += chars;
 136                 if (*bhe) {
 137                         memcpy_tofs(buf,offset+(*bhe)->b_data,chars);
 138                         brelse(*bhe);
 139                         buf += chars;
 140                 } else {
 141                         while (chars-->0)
 142                                 put_fs_byte(0,buf++);
 143                 }
 144                 offset = 0;
 145                 if (++bhe == &buflist[NBUF])
 146                         bhe = buflist;
 147         } while (left > 0);
 148         if (!read)
 149                 return -EIO;
 150         if (!IS_RDONLY(inode)) {
 151                 inode->i_atime = CURRENT_TIME;
 152                 inode->i_dirt = 1;
 153         }
 154         return read;
 155 }
 156 
 157 static int ext_file_write(struct inode * inode, struct file * filp, char * buf, int count)
     /*  */
 158 {
 159         off_t pos;
 160         int written,c;
 161         struct buffer_head * bh;
 162         char * p;
 163 
 164         if (!inode) {
 165                 printk("ext_file_write: inode = NULL\n");
 166                 return -EINVAL;
 167         }
 168         if (!S_ISREG(inode->i_mode)) {
 169                 printk("ext_file_write: mode = %07o\n",inode->i_mode);
 170                 return -EINVAL;
 171         }
 172 /*
 173  * ok, append may not work when many processes are writing at the same time
 174  * but so what. That way leads to madness anyway.
 175  */
 176         if (filp->f_flags & O_APPEND)
 177                 pos = inode->i_size;
 178         else
 179                 pos = filp->f_pos;
 180         written = 0;
 181         while (written<count) {
 182                 bh = ext_getblk(inode,pos/BLOCK_SIZE,1);
 183                 if (!bh) {
 184                         if (!written)
 185                                 written = -ENOSPC;
 186                         break;
 187                 }
 188                 c = BLOCK_SIZE - (pos % BLOCK_SIZE);
 189                 if (c > count-written)
 190                         c = count-written;
 191                 if (c != BLOCK_SIZE && !bh->b_uptodate) {
 192                         ll_rw_block(READ,bh);
 193                         wait_on_buffer(bh);
 194                         if (!bh->b_uptodate) {
 195                                 brelse(bh);
 196                                 if (!written)
 197                                         written = -EIO;
 198                                 break;
 199                         }
 200                 }
 201                 p = (pos % BLOCK_SIZE) + bh->b_data;
 202                 pos += c;
 203                 if (pos > inode->i_size) {
 204                         inode->i_size = pos;
 205                         inode->i_dirt = 1;
 206                 }
 207                 written += c;
 208                 memcpy_fromfs(p,buf,c);
 209                 buf += c;
 210                 bh->b_uptodate = 1;
 211                 bh->b_dirt = 1;
 212                 brelse(bh);
 213         }
 214         inode->i_mtime = CURRENT_TIME;
 215         inode->i_ctime = CURRENT_TIME;
 216         filp->f_pos = pos;
 217         inode->i_dirt = 1;
 218         return written;
 219 }
/* */
root/fs/ext/file.c

DEFINITIONS
