fs/coda/file.c

   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/time.h>
  13 #include <linux/file.h>
  14 #include <linux/fs.h>
  15 #include <linux/stat.h>
  16 #include <linux/cred.h>
  17 #include <linux/errno.h>
  18 #include <linux/spinlock.h>
  19 #include <linux/string.h>
  20 #include <linux/slab.h>
  21 #include <linux/uaccess.h>
  22
  23 #include <linux/coda.h>
  24 #include <linux/coda_psdev.h>
  25
  26 #include "coda_linux.h"
  27 #include "coda_int.h"
  28
  29 static ssize_t
  30 coda_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
  31 {
  32         struct file *coda_file = iocb->ki_filp;
  33         struct coda_file_info *cfi = CODA_FTOC(coda_file);
  34
  35         BUG_ON(!cfi || cfi->cfi_magic != CODA_MAGIC);
  36
  37         return vfs_iter_read(cfi->cfi_container, to, &iocb->ki_pos);
  38 }
  39
  40 static ssize_t
  41 coda_file_splice_read(struct file *coda_file, loff_t *ppos,
  42                       struct pipe_inode_info *pipe, size_t count,
  43                       unsigned int flags)
  44 {
  45         ssize_t (*splice_read)(struct file *, loff_t *,
  46                                struct pipe_inode_info *, size_t, unsigned int);
  47         struct coda_file_info *cfi;
  48         struct file *host_file;
  49
  50         cfi = CODA_FTOC(coda_file);
  51         BUG_ON(!cfi || cfi->cfi_magic != CODA_MAGIC);
  52         host_file = cfi->cfi_container;
  53
  54         splice_read = host_file->f_op->splice_read;
  55         if (!splice_read)
  56                 splice_read = default_file_splice_read;
  57
  58         return splice_read(host_file, ppos, pipe, count, flags);
  59 }
  60
  61 static ssize_t
  62 coda_file_write_iter(struct kiocb *iocb, struct iov_iter *to)
  63 {
  64         struct file *coda_file = iocb->ki_filp;
  65         struct inode *coda_inode = file_inode(coda_file);
  66         struct coda_file_info *cfi = CODA_FTOC(coda_file);
  67         struct file *host_file;
  68         ssize_t ret;
  69
  70         BUG_ON(!cfi || cfi->cfi_magic != CODA_MAGIC);
  71
  72         host_file = cfi->cfi_container;
  73         file_start_write(host_file);
  74         mutex_lock(&coda_inode->i_mutex);
  75         ret = vfs_iter_write(cfi->cfi_container, to, &iocb->ki_pos);
  76         coda_inode->i_size = file_inode(host_file)->i_size;
  77         coda_inode->i_blocks = (coda_inode->i_size + 511) >> 9;
  78         coda_inode->i_mtime = coda_inode->i_ctime = CURRENT_TIME_SEC;
  79         mutex_unlock(&coda_inode->i_mutex);
  80         file_end_write(host_file);
  81         return ret;
  82 }
  83
  84 static int
  85 coda_file_mmap(struct file *coda_file, struct vm_area_struct *vma)
  86 {
  87         struct coda_file_info *cfi;
  88         struct coda_inode_info *cii;
  89         struct file *host_file;
  90         struct inode *coda_inode, *host_inode;
  91
  92         cfi = CODA_FTOC(coda_file);
  93         BUG_ON(!cfi || cfi->cfi_magic != CODA_MAGIC);
  94         host_file = cfi->cfi_container;
  95
  96         if (!host_file->f_op->mmap)
  97                 return -ENODEV;
  98
  99         coda_inode = file_inode(coda_file);
 100         host_inode = file_inode(host_file);
 101
 102         cii = ITOC(coda_inode);
 103         spin_lock(&cii->c_lock);
 104         coda_file->f_mapping = host_file->f_mapping;
 105         if (coda_inode->i_mapping == &coda_inode->i_data)
 106                 coda_inode->i_mapping = host_inode->i_mapping;
 107
 108         /* only allow additional mmaps as long as userspace isn't changing
 109          * the container file on us! */
 110         else if (coda_inode->i_mapping != host_inode->i_mapping) {
 111                 spin_unlock(&cii->c_lock);
 112                 return -EBUSY;
 113         }
 114
 115         /* keep track of how often the coda_inode/host_file has been mmapped */
 116         cii->c_mapcount++;
 117         cfi->cfi_mapcount++;
 118         spin_unlock(&cii->c_lock);
 119
 120         return host_file->f_op->mmap(host_file, vma);
 121 }
 122
 123 int coda_open(struct inode *coda_inode, struct file *coda_file)
 124 {
 125         struct file *host_file = NULL;
 126         int error;
 127         unsigned short flags = coda_file->f_flags & (~O_EXCL);
 128         unsigned short coda_flags = coda_flags_to_cflags(flags);
 129         struct coda_file_info *cfi;
 130
 131         cfi = kmalloc(sizeof(struct coda_file_info), GFP_KERNEL);
 132         if (!cfi)
 133                 return -ENOMEM;
 134
 135         error = venus_open(coda_inode->i_sb, coda_i2f(coda_inode), coda_flags,
 136                            &host_file);
 137         if (!host_file)
 138                 error = -EIO;
 139
 140         if (error) {
 141                 kfree(cfi);
 142                 return error;
 143         }
 144
 145         host_file->f_flags |= coda_file->f_flags & (O_APPEND | O_SYNC);
 146
 147         cfi->cfi_magic = CODA_MAGIC;
 148         cfi->cfi_mapcount = 0;
 149         cfi->cfi_container = host_file;
 150
 151         BUG_ON(coda_file->private_data != NULL);
 152         coda_file->private_data = cfi;
 153         return 0;
 154 }
 155
 156 int coda_release(struct inode *coda_inode, struct file *coda_file)
 157 {
 158         unsigned short flags = (coda_file->f_flags) & (~O_EXCL);
 159         unsigned short coda_flags = coda_flags_to_cflags(flags);
 160         struct coda_file_info *cfi;
 161         struct coda_inode_info *cii;
 162         struct inode *host_inode;
 163         int err;
 164
 165         cfi = CODA_FTOC(coda_file);
 166         BUG_ON(!cfi || cfi->cfi_magic != CODA_MAGIC);
 167
 168         err = venus_close(coda_inode->i_sb, coda_i2f(coda_inode),
 169                           coda_flags, coda_file->f_cred->fsuid);
 170
 171         host_inode = file_inode(cfi->cfi_container);
 172         cii = ITOC(coda_inode);
 173
 174         /* did we mmap this file? */
 175         spin_lock(&cii->c_lock);
 176         if (coda_inode->i_mapping == &host_inode->i_data) {
 177                 cii->c_mapcount -= cfi->cfi_mapcount;
 178                 if (!cii->c_mapcount)
 179                         coda_inode->i_mapping = &coda_inode->i_data;
 180         }
 181         spin_unlock(&cii->c_lock);
 182
 183         fput(cfi->cfi_container);
 184         kfree(coda_file->private_data);
 185         coda_file->private_data = NULL;
 186
 187         /* VFS fput ignores the return value from file_operations->release, so
 188          * there is no use returning an error here */
 189         return 0;
 190 }
 191
 192 int coda_fsync(struct file *coda_file, loff_t start, loff_t end, int datasync)
 193 {
 194         struct file *host_file;
 195         struct inode *coda_inode = file_inode(coda_file);
 196         struct coda_file_info *cfi;
 197         int err;
 198
 199         if (!(S_ISREG(coda_inode->i_mode) || S_ISDIR(coda_inode->i_mode) ||
 200               S_ISLNK(coda_inode->i_mode)))
 201                 return -EINVAL;
 202
 203         err = filemap_write_and_wait_range(coda_inode->i_mapping, start, end);
 204         if (err)
 205                 return err;
 206         mutex_lock(&coda_inode->i_mutex);
 207
 208         cfi = CODA_FTOC(coda_file);
 209         BUG_ON(!cfi || cfi->cfi_magic != CODA_MAGIC);
 210         host_file = cfi->cfi_container;
 211
 212         err = vfs_fsync(host_file, datasync);
 213         if (!err && !datasync)
 214                 err = venus_fsync(coda_inode->i_sb, coda_i2f(coda_inode));
 215         mutex_unlock(&coda_inode->i_mutex);
 216
 217         return err;
 218 }
 219
 220 const struct file_operations coda_file_operations = {
 221         .llseek         = generic_file_llseek,
 222         .read_iter      = coda_file_read_iter,
 223         .write_iter     = coda_file_write_iter,
 224         .mmap           = coda_file_mmap,
 225         .open           = coda_open,
 226         .release        = coda_release,
 227         .fsync          = coda_fsync,
 228         .splice_read    = coda_file_splice_read,
 229 };
 230