The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


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FreeBSD/Linux Kernel Cross Reference
sys/fs/coda/file.c

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    1 /*
    2  * File operations for Coda.
    3  * Original version: (C) 1996 Peter Braam 
    4  * Rewritten for Linux 2.1: (C) 1997 Carnegie Mellon University
    5  *
    6  * Carnegie Mellon encourages users of this code to contribute improvements
    7  * to the Coda project. Contact Peter Braam <coda@cs.cmu.edu>.
    8  */
    9 
   10 #include <linux/types.h>
   11 #include <linux/kernel.h>
   12 #include <linux/sched.h>
   13 #include <linux/file.h>
   14 #include <linux/fs.h>
   15 #include <linux/stat.h>
   16 #include <linux/errno.h>
   17 #include <linux/locks.h>
   18 #include <linux/smp_lock.h>
   19 #include <linux/string.h>
   20 #include <asm/uaccess.h>
   21 
   22 #include <linux/coda.h>
   23 #include <linux/coda_linux.h>
   24 #include <linux/coda_fs_i.h>
   25 #include <linux/coda_psdev.h>
   26 #include <linux/coda_proc.h>
   27 
   28 /* if CODA_STORE fails with EOPNOTSUPP, venus clearly doesn't support
   29  * CODA_STORE/CODA_RELEASE and we fall back on using the CODA_CLOSE upcall */
   30 int use_coda_close;
   31 
   32 static ssize_t
   33 coda_file_read(struct file *coda_file, char *buf, size_t count, loff_t *ppos)
   34 {
   35         struct coda_file_info *cfi;
   36         struct file *host_file;
   37 
   38         cfi = CODA_FTOC(coda_file);
   39         if (!cfi || cfi->cfi_magic != CODA_MAGIC) BUG();
   40         host_file = cfi->cfi_container;
   41 
   42         if (!host_file->f_op || !host_file->f_op->read)
   43                 return -EINVAL;
   44 
   45         return host_file->f_op->read(host_file, buf, count, ppos);
   46 }
   47 
   48 static ssize_t
   49 coda_file_write(struct file *coda_file, const char *buf, size_t count, loff_t *ppos)
   50 {
   51         struct inode *coda_inode = coda_file->f_dentry->d_inode;
   52         struct coda_file_info *cfi;
   53         struct file *host_file;
   54         ssize_t ret;
   55 
   56         cfi = CODA_FTOC(coda_file);
   57         if (!cfi || cfi->cfi_magic != CODA_MAGIC) BUG();
   58         host_file = cfi->cfi_container;
   59 
   60         if (!host_file->f_op || !host_file->f_op->write)
   61                 return -EINVAL;
   62 
   63         down(&coda_inode->i_sem);
   64 
   65         ret = host_file->f_op->write(host_file, buf, count, ppos);
   66 
   67         coda_inode->i_size = host_file->f_dentry->d_inode->i_size;
   68         coda_inode->i_blocks = (coda_inode->i_size + 511) >> 9;
   69         coda_inode->i_mtime = coda_inode->i_ctime = CURRENT_TIME;
   70         up(&coda_inode->i_sem);
   71 
   72         return ret;
   73 }
   74 
   75 static int
   76 coda_file_mmap(struct file *coda_file, struct vm_area_struct *vma)
   77 {
   78         struct coda_file_info *cfi;
   79         struct coda_inode_info *cii;
   80         struct file *host_file;
   81         struct inode *coda_inode, *host_inode;
   82 
   83         cfi = CODA_FTOC(coda_file);
   84         if (!cfi || cfi->cfi_magic != CODA_MAGIC) BUG();
   85         host_file = cfi->cfi_container;
   86 
   87         if (!host_file->f_op || !host_file->f_op->mmap)
   88                 return -ENODEV;
   89 
   90         coda_inode = coda_file->f_dentry->d_inode;
   91         host_inode = host_file->f_dentry->d_inode;
   92         if (coda_inode->i_mapping == &coda_inode->i_data)
   93                 coda_inode->i_mapping = host_inode->i_mapping;
   94 
   95         /* only allow additional mmaps as long as userspace isn't changing
   96          * the container file on us! */
   97         else if (coda_inode->i_mapping != host_inode->i_mapping)
   98                 return -EBUSY;
   99 
  100         /* keep track of how often the coda_inode/host_file has been mmapped */
  101         cii = ITOC(coda_inode);
  102         cii->c_mapcount++;
  103         cfi->cfi_mapcount++;
  104  
  105         return host_file->f_op->mmap(host_file, vma);
  106 }
  107 
  108 int coda_open(struct inode *coda_inode, struct file *coda_file)
  109 {
  110         struct file *host_file = NULL;
  111         int error;
  112         unsigned short flags = coda_file->f_flags & (~O_EXCL);
  113         unsigned short coda_flags = coda_flags_to_cflags(flags);
  114         struct coda_file_info *cfi;
  115         struct inode *host_inode;
  116 
  117         coda_vfs_stat.open++;
  118 
  119         cfi = kmalloc(sizeof(struct coda_file_info), GFP_KERNEL);
  120         if (!cfi)
  121                 return -ENOMEM;
  122 
  123         lock_kernel();
  124 
  125         error = venus_open(coda_inode->i_sb, coda_i2f(coda_inode), coda_flags,
  126                            &host_file); 
  127 
  128         if (!error && !host_file)
  129                 error = EBADF;
  130 
  131         if (error) {
  132                 kfree(cfi);
  133                 unlock_kernel();
  134                 return error;
  135         }
  136 
  137         host_file->f_flags |= coda_file->f_flags & (O_APPEND | O_SYNC);
  138 
  139         cfi->cfi_magic = CODA_MAGIC;
  140         cfi->cfi_mapcount = 0;
  141         cfi->cfi_container = host_file;
  142         coda_load_creds(&cfi->cfi_cred);
  143 
  144         host_inode = host_file->f_dentry->d_inode;
  145         if (coda_inode->i_mapping == &coda_inode->i_data)
  146                 coda_inode->i_mapping = host_inode->i_mapping;
  147 
  148         else if (coda_inode->i_mapping != host_inode->i_mapping) {
  149                 /* This is not a good thing, it doesn't happen with 'venus'
  150                  * Coda's own userspace daemon, but others might not provide
  151                  * the same guarantees. Still looking for the real fix. */
  152                 printk("coda_open: changed mapping\n");
  153                 coda_inode->i_mapping = host_inode->i_mapping;
  154         }
  155 
  156         if (coda_file->private_data != NULL) BUG();
  157         coda_file->private_data = cfi;
  158 
  159         unlock_kernel();
  160         return 0;
  161 }
  162 
  163 int coda_flush(struct file *coda_file)
  164 {
  165         unsigned short flags = coda_file->f_flags & ~O_EXCL;
  166         unsigned short coda_flags = coda_flags_to_cflags(flags);
  167         struct coda_file_info *cfi;
  168         struct inode *coda_inode;
  169         int err = 0, fcnt;
  170 
  171         coda_vfs_stat.flush++;
  172 
  173         /* No need to make an upcall when we have not made any modifications
  174          * to the file */
  175         if ((coda_file->f_flags & O_ACCMODE) == O_RDONLY)
  176                 return 0;
  177 
  178         if (use_coda_close)
  179                 return 0;
  180 
  181         fcnt = file_count(coda_file);
  182         if (fcnt > 1) return 0;
  183 
  184         coda_inode = coda_file->f_dentry->d_inode;
  185 
  186         cfi = CODA_FTOC(coda_file);
  187         if (!cfi || cfi->cfi_magic != CODA_MAGIC) BUG();
  188 
  189         err = venus_store(coda_inode->i_sb, coda_i2f(coda_inode), coda_flags,
  190                           &cfi->cfi_cred);
  191 
  192         if (err == -EOPNOTSUPP) {
  193                 use_coda_close = 1;
  194                 err = 0;
  195         }
  196 
  197         return err;
  198 }
  199 
  200 int coda_release(struct inode *coda_inode, struct file *coda_file)
  201 {
  202         unsigned short flags = (coda_file->f_flags) & (~O_EXCL);
  203         unsigned short coda_flags = coda_flags_to_cflags(flags);
  204         struct coda_file_info *cfi;
  205         struct coda_inode_info *cii;
  206         struct inode *host_inode;
  207         int err = 0;
  208 
  209         lock_kernel();
  210         coda_vfs_stat.release++;
  211  
  212         if (!use_coda_close) {
  213                 err = venus_release(coda_inode->i_sb, coda_i2f(coda_inode),
  214                                     coda_flags);
  215                 if (err == -EOPNOTSUPP) {
  216                         use_coda_close = 1;
  217                         err = 0;
  218                 }
  219         }
  220 
  221         cfi = CODA_FTOC(coda_file);
  222         if (!cfi || cfi->cfi_magic != CODA_MAGIC) BUG();
  223 
  224         if (use_coda_close)
  225                 err = venus_close(coda_inode->i_sb, coda_i2f(coda_inode),
  226                                   coda_flags, &cfi->cfi_cred);
  227 
  228         host_inode = cfi->cfi_container->f_dentry->d_inode;
  229         cii = ITOC(coda_inode);
  230 
  231         /* did we mmap this file? */
  232         if (coda_inode->i_mapping == &host_inode->i_data) {
  233                 cii->c_mapcount -= cfi->cfi_mapcount;
  234                 if (!cii->c_mapcount)
  235                         coda_inode->i_mapping = &coda_inode->i_data;
  236         }
  237 
  238         fput(cfi->cfi_container);
  239 
  240         kfree(coda_file->private_data);
  241         coda_file->private_data = NULL;
  242 
  243         unlock_kernel();
  244         return err;
  245 }
  246 
  247 int coda_fsync(struct file *coda_file, struct dentry *coda_dentry, int datasync)
  248 {
  249         struct file *host_file;
  250         struct dentry *host_dentry;
  251         struct inode *host_inode, *coda_inode = coda_dentry->d_inode;
  252         struct coda_file_info *cfi;
  253         int err = 0;
  254 
  255         if (!(S_ISREG(coda_inode->i_mode) || S_ISDIR(coda_inode->i_mode) ||
  256               S_ISLNK(coda_inode->i_mode)))
  257                 return -EINVAL;
  258 
  259         cfi = CODA_FTOC(coda_file);
  260         if (!cfi || cfi->cfi_magic != CODA_MAGIC) BUG();
  261         host_file = cfi->cfi_container;
  262 
  263         coda_vfs_stat.fsync++;
  264 
  265         if (host_file->f_op && host_file->f_op->fsync) {
  266                 host_dentry = host_file->f_dentry;
  267                 host_inode = host_dentry->d_inode;
  268                 down(&host_inode->i_sem);
  269                 err = host_file->f_op->fsync(host_file, host_dentry, datasync);
  270                 up(&host_inode->i_sem);
  271         }
  272 
  273         if ( !err && !datasync ) {
  274                 lock_kernel();
  275                 err = venus_fsync(coda_inode->i_sb, coda_i2f(coda_inode));
  276                 unlock_kernel();
  277         }
  278 
  279         return err;
  280 }
  281 
  282 struct file_operations coda_file_operations = {
  283         llseek:         generic_file_llseek,
  284         read:           coda_file_read,
  285         write:          coda_file_write,
  286         mmap:           coda_file_mmap,
  287         open:           coda_open,
  288         flush:          coda_flush,
  289         release:        coda_release,
  290         fsync:          coda_fsync,
  291 };
  292 

Cache object: 4c9aa5b30cceed4f37c62a7da03db254


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