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_write_iter(struct kiocb *iocb, struct iov_iter *to)
  42 {
  43         struct file *coda_file = iocb->ki_filp;
  44         struct inode *coda_inode = file_inode(coda_file);
  45         struct coda_file_info *cfi = CODA_FTOC(coda_file);
  46         struct file *host_file;
  47         ssize_t ret;
  48
  49         BUG_ON(!cfi || cfi->cfi_magic != CODA_MAGIC);
  50
  51         host_file = cfi->cfi_container;
  52         file_start_write(host_file);
  53         inode_lock(coda_inode);
  54         ret = vfs_iter_write(cfi->cfi_container, to, &iocb->ki_pos);
  55         coda_inode->i_size = file_inode(host_file)->i_size;
  56         coda_inode->i_blocks = (coda_inode->i_size + 511) >> 9;
  57         coda_inode->i_mtime = coda_inode->i_ctime = current_time(coda_inode);
  58         inode_unlock(coda_inode);
  59         file_end_write(host_file);
  60         return ret;
  61 }
  62
  63 static int
  64 coda_file_mmap(struct file *coda_file, struct vm_area_struct *vma)
  65 {
  66         struct coda_file_info *cfi;
  67         struct coda_inode_info *cii;
  68         struct file *host_file;
  69         struct inode *coda_inode, *host_inode;
  70
  71         cfi = CODA_FTOC(coda_file);
  72         BUG_ON(!cfi || cfi->cfi_magic != CODA_MAGIC);
  73         host_file = cfi->cfi_container;
  74
  75         if (!host_file->f_op->mmap)
  76                 return -ENODEV;
  77
  78         coda_inode = file_inode(coda_file);
  79         host_inode = file_inode(host_file);
  80
  81         cii = ITOC(coda_inode);
  82         spin_lock(&cii->c_lock);
  83         coda_file->f_mapping = host_file->f_mapping;
  84         if (coda_inode->i_mapping == &coda_inode->i_data)
  85                 coda_inode->i_mapping = host_inode->i_mapping;
  86
  87         /* only allow additional mmaps as long as userspace isn't changing
  88          * the container file on us! */
  89         else if (coda_inode->i_mapping != host_inode->i_mapping) {
  90                 spin_unlock(&cii->c_lock);
  91                 return -EBUSY;
  92         }
  93
  94         /* keep track of how often the coda_inode/host_file has been mmapped */
  95         cii->c_mapcount++;
  96         cfi->cfi_mapcount++;
  97         spin_unlock(&cii->c_lock);
  98
  99         return host_file->f_op->mmap(host_file, vma);
 100 }
 101
 102 int coda_open(struct inode *coda_inode, struct file *coda_file)
 103 {
 104         struct file *host_file = NULL;
 105         int error;
 106         unsigned short flags = coda_file->f_flags & (~O_EXCL);
 107         unsigned short coda_flags = coda_flags_to_cflags(flags);
 108         struct coda_file_info *cfi;
 109
 110         cfi = kmalloc(sizeof(struct coda_file_info), GFP_KERNEL);
 111         if (!cfi)
 112                 return -ENOMEM;
 113
 114         error = venus_open(coda_inode->i_sb, coda_i2f(coda_inode), coda_flags,
 115                            &host_file);
 116         if (!host_file)
 117                 error = -EIO;
 118
 119         if (error) {
 120                 kfree(cfi);
 121                 return error;
 122         }
 123
 124         host_file->f_flags |= coda_file->f_flags & (O_APPEND | O_SYNC);
 125
 126         cfi->cfi_magic = CODA_MAGIC;
 127         cfi->cfi_mapcount = 0;
 128         cfi->cfi_container = host_file;
 129
 130         BUG_ON(coda_file->private_data != NULL);
 131         coda_file->private_data = cfi;
 132         return 0;
 133 }
 134
 135 int coda_release(struct inode *coda_inode, struct file *coda_file)
 136 {
 137         unsigned short flags = (coda_file->f_flags) & (~O_EXCL);
 138         unsigned short coda_flags = coda_flags_to_cflags(flags);
 139         struct coda_file_info *cfi;
 140         struct coda_inode_info *cii;
 141         struct inode *host_inode;
 142         int err;
 143
 144         cfi = CODA_FTOC(coda_file);
 145         BUG_ON(!cfi || cfi->cfi_magic != CODA_MAGIC);
 146
 147         err = venus_close(coda_inode->i_sb, coda_i2f(coda_inode),
 148                           coda_flags, coda_file->f_cred->fsuid);
 149
 150         host_inode = file_inode(cfi->cfi_container);
 151         cii = ITOC(coda_inode);
 152
 153         /* did we mmap this file? */
 154         spin_lock(&cii->c_lock);
 155         if (coda_inode->i_mapping == &host_inode->i_data) {
 156                 cii->c_mapcount -= cfi->cfi_mapcount;
 157                 if (!cii->c_mapcount)
 158                         coda_inode->i_mapping = &coda_inode->i_data;
 159         }
 160         spin_unlock(&cii->c_lock);
 161
 162         fput(cfi->cfi_container);
 163         kfree(coda_file->private_data);
 164         coda_file->private_data = NULL;
 165
 166         /* VFS fput ignores the return value from file_operations->release, so
 167          * there is no use returning an error here */
 168         return 0;
 169 }
 170
 171 int coda_fsync(struct file *coda_file, loff_t start, loff_t end, int datasync)
 172 {
 173         struct file *host_file;
 174         struct inode *coda_inode = file_inode(coda_file);
 175         struct coda_file_info *cfi;
 176         int err;
 177
 178         if (!(S_ISREG(coda_inode->i_mode) || S_ISDIR(coda_inode->i_mode) ||
 179               S_ISLNK(coda_inode->i_mode)))
 180                 return -EINVAL;
 181
 182         err = filemap_write_and_wait_range(coda_inode->i_mapping, start, end);
 183         if (err)
 184                 return err;
 185         inode_lock(coda_inode);
 186
 187         cfi = CODA_FTOC(coda_file);
 188         BUG_ON(!cfi || cfi->cfi_magic != CODA_MAGIC);
 189         host_file = cfi->cfi_container;
 190
 191         err = vfs_fsync(host_file, datasync);
 192         if (!err && !datasync)
 193                 err = venus_fsync(coda_inode->i_sb, coda_i2f(coda_inode));
 194         inode_unlock(coda_inode);
 195
 196         return err;
 197 }
 198
 199 const struct file_operations coda_file_operations = {
 200         .llseek         = generic_file_llseek,
 201         .read_iter      = coda_file_read_iter,
 202         .write_iter     = coda_file_write_iter,
 203         .mmap           = coda_file_mmap,
 204         .open           = coda_open,
 205         .release        = coda_release,
 206         .fsync          = coda_fsync,
 207         .splice_read    = generic_file_splice_read,
 208 };
 209