fs/nfs/file.c

   1 /*
   2  *  linux/fs/nfs/file.c
   3  *
   4  *  Copyright (C) 1992  Rick Sladkey
   5  *
   6  *  Changes Copyright (C) 1994 by Florian La Roche
   7  *   - Do not copy data too often around in the kernel.
   8  *   - In nfs_file_read the return value of kmalloc wasn't checked.
   9  *   - Put in a better version of read look-ahead buffering. Original idea
  10  *     and implementation by Wai S Kok elekokws@ee.nus.sg.
  11  *
  12  *  Expire cache on write to a file by Wai S Kok (Oct 1994).
  13  *
  14  *  Total rewrite of read side for new NFS buffer cache.. Linus.
  15  *
  16  *  nfs regular file handling functions
  17  */
  18
  19 #include <linux/sched.h>
  20 #include <linux/kernel.h>
  21 #include <linux/errno.h>
  22 #include <linux/fcntl.h>
  23 #include <linux/stat.h>
  24 #include <linux/nfs_fs.h>
  25 #include <linux/nfs_mount.h>
  26 #include <linux/mm.h>
  27 #include <linux/malloc.h>
  28 #include <linux/pagemap.h>
  29 #include <linux/lockd/bind.h>
  30 #include <linux/smp_lock.h>
  31
  32 #include <asm/uaccess.h>
  33 #include <asm/system.h>
  34
  35 #define NFSDBG_FACILITY         NFSDBG_FILE
  36
  37 static int  nfs_file_mmap(struct file *, struct vm_area_struct *);
  38 static ssize_t nfs_file_read(struct file *, char *, size_t, loff_t *);
  39 static ssize_t nfs_file_write(struct file *, const char *, size_t, loff_t *);
  40 static int  nfs_file_flush(struct file *);
  41 static int  nfs_fsync(struct file *, struct dentry *dentry);
  42
  43 struct file_operations nfs_file_operations = {
  44         read:           nfs_file_read,
  45         write:          nfs_file_write,
  46         mmap:           nfs_file_mmap,
  47         open:           nfs_open,
  48         flush:          nfs_file_flush,
  49         release:        nfs_release,
  50         fsync:          nfs_fsync,
  51         lock:           nfs_lock,
  52 };
  53
  54 struct inode_operations nfs_file_inode_operations = {
  55         revalidate:     nfs_revalidate,
  56         setattr:        nfs_notify_change,
  57 };
  58
  59 /* Hack for future NFS swap support */
  60 #ifndef IS_SWAPFILE
  61 # define IS_SWAPFILE(inode)     (0)
  62 #endif
  63
  64 /*
  65  * Flush all dirty pages, and check for write errors.
  66  *
  67  */
  68 static int
  69 nfs_file_flush(struct file *file)
  70 {
  71         struct inode    *inode = file->f_dentry->d_inode;
  72         int             status;
  73
  74         dfprintk(VFS, "nfs: flush(%x/%ld)\n", inode->i_dev, inode->i_ino);
  75
  76         /* Make sure all async reads have been sent off. We don't bother
  77          * waiting on them though... */
  78         if (file->f_mode & FMODE_READ)
  79                 nfs_pagein_inode(inode, 0, 0);
  80
  81         status = nfs_wb_file(inode, file);
  82         if (!status) {
  83                 status = file->f_error;
  84                 file->f_error = 0;
  85         }
  86         return status;
  87 }
  88
  89 static ssize_t
  90 nfs_file_read(struct file * file, char * buf, size_t count, loff_t *ppos)
  91 {
  92         struct dentry * dentry = file->f_dentry;
  93         ssize_t result;
  94
  95         dfprintk(VFS, "nfs: read(%s/%s, %lu@%lu)\n",
  96                 dentry->d_parent->d_name.name, dentry->d_name.name,
  97                 (unsigned long) count, (unsigned long) *ppos);
  98
  99         result = nfs_revalidate_inode(NFS_DSERVER(dentry), dentry);
 100         if (!result)
 101                 result = generic_file_read(file, buf, count, ppos);
 102         return result;
 103 }
 104
 105 static int
 106 nfs_file_mmap(struct file * file, struct vm_area_struct * vma)
 107 {
 108         struct dentry *dentry = file->f_dentry;
 109         int     status;
 110
 111         dfprintk(VFS, "nfs: mmap(%s/%s)\n",
 112                 dentry->d_parent->d_name.name, dentry->d_name.name);
 113
 114         status = nfs_revalidate_inode(NFS_DSERVER(dentry), dentry);
 115         if (!status)
 116                 status = generic_file_mmap(file, vma);
 117         return status;
 118 }
 119
 120 /*
 121  * Flush any dirty pages for this process, and check for write errors.
 122  * The return status from this call provides a reliable indication of
 123  * whether any write errors occurred for this process.
 124  */
 125 static int
 126 nfs_fsync(struct file *file, struct dentry *dentry)
 127 {
 128         struct inode *inode = dentry->d_inode;
 129         int status;
 130
 131         dfprintk(VFS, "nfs: fsync(%x/%ld)\n", inode->i_dev, inode->i_ino);
 132
 133         lock_kernel();
 134         status = nfs_wb_file(inode, file);
 135         if (!status) {
 136                 status = file->f_error;
 137                 file->f_error = 0;
 138         }
 139         unlock_kernel();
 140         return status;
 141 }
 142
 143 /*
 144  * This does the "real" work of the write. The generic routine has
 145  * allocated the page, locked it, done all the page alignment stuff
 146  * calculations etc. Now we should just copy the data from user
 147  * space and write it back to the real medium..
 148  *
 149  * If the writer ends up delaying the write, the writer needs to
 150  * increment the page use counts until he is done with the page.
 151  */
 152 static int nfs_prepare_write(struct file *file, struct page *page, unsigned offset, unsigned to)
 153 {
 154         kmap(page);
 155         return nfs_flush_incompatible(file, page);
 156 }
 157 static int nfs_commit_write(struct file *file, struct page *page, unsigned offset, unsigned to)
 158 {
 159         long status;
 160         loff_t pos = ((loff_t)page->index<<PAGE_CACHE_SHIFT) + to;
 161         struct inode *inode = (struct inode*)page->mapping->host;
 162
 163         kunmap(page);
 164         lock_kernel();
 165         status = nfs_updatepage(file, page, offset, to-offset);
 166         unlock_kernel();
 167         /* most likely it's already done. CHECKME */
 168         if (pos > inode->i_size)
 169                 inode->i_size = pos;
 170         return status;
 171 }
 172
 173 /*
 174  * The following is used by wait_on_page(), generic_file_readahead()
 175  * to initiate the completion of any page readahead operations.
 176  */
 177 static int nfs_sync_page(struct page *page)
 178 {
 179         struct inode    *inode = (struct inode *)page->mapping->host;
 180         unsigned long   index = page_index(page);
 181         unsigned int    rpages, wpages;
 182         int             result;
 183
 184         if (!inode)
 185                 return 0;
 186
 187         rpages = NFS_SERVER(inode)->rpages;
 188         result = nfs_pagein_inode(inode, index, rpages);
 189         if (result < 0)
 190                 goto out_bad;
 191         wpages = NFS_SERVER(inode)->wpages;
 192         result = nfs_sync_file(inode, NULL, index, wpages, FLUSH_STABLE);
 193         if (result < 0)
 194                 goto out_bad;
 195         return 0;
 196  out_bad:
 197         return result;
 198 }
 199
 200 struct address_space_operations nfs_file_aops = {
 201         readpage: nfs_readpage,
 202         sync_page: nfs_sync_page,
 203         writepage: nfs_writepage,
 204         prepare_write: nfs_prepare_write,
 205         commit_write: nfs_commit_write
 206 };
 207
 208 /*
 209  * Write to a file (through the page cache).
 210  */
 211 static ssize_t
 212 nfs_file_write(struct file *file, const char *buf, size_t count, loff_t *ppos)
 213 {
 214         struct dentry * dentry = file->f_dentry;
 215         struct inode * inode = dentry->d_inode;
 216         ssize_t result;
 217
 218         dfprintk(VFS, "nfs: write(%s/%s(%ld), %lu@%lu)\n",
 219                 dentry->d_parent->d_name.name, dentry->d_name.name,
 220                 inode->i_ino, (unsigned long) count, (unsigned long) *ppos);
 221
 222         result = -EBUSY;
 223         if (IS_SWAPFILE(inode))
 224                 goto out_swapfile;
 225         result = nfs_revalidate_inode(NFS_DSERVER(dentry), dentry);
 226         if (result)
 227                 goto out;
 228
 229         result = count;
 230         if (!count)
 231                 goto out;
 232
 233         result = generic_file_write(file, buf, count, ppos);
 234 out:
 235         return result;
 236
 237 out_swapfile:
 238         printk(KERN_INFO "NFS: attempt to write to active swap file!\n");
 239         goto out;
 240 }
 241
 242 /*
 243  * Lock a (portion of) a file
 244  */
 245 int
 246 nfs_lock(struct file *filp, int cmd, struct file_lock *fl)
 247 {
 248         struct inode * inode = filp->f_dentry->d_inode;
 249         int     status = 0;
 250
 251         dprintk("NFS: nfs_lock(f=%4x/%ld, t=%x, fl=%x, r=%Ld:%Ld)\n",
 252                         inode->i_dev, inode->i_ino,
 253                         fl->fl_type, fl->fl_flags,
 254                         (long long)fl->fl_start, (long long)fl->fl_end);
 255
 256         if (!inode)
 257                 return -EINVAL;
 258
 259         /* No mandatory locks over NFS */
 260         if ((inode->i_mode & (S_ISGID | S_IXGRP)) == S_ISGID)
 261                 return -ENOLCK;
 262
 263         /* Fake OK code if mounted without NLM support */
 264         if (NFS_SERVER(inode)->flags & NFS_MOUNT_NONLM) {
 265                 if (cmd == F_GETLK)
 266                         status = LOCK_USE_CLNT;
 267                 goto out_ok;
 268         }
 269
 270         /*
 271          * No BSD flocks over NFS allowed.
 272          * Note: we could try to fake a POSIX lock request here by
 273          * using ((u32) filp | 0x80000000) or some such as the pid.
 274          * Not sure whether that would be unique, though, or whether
 275          * that would break in other places.
 276          */
 277         if (!fl->fl_owner || (fl->fl_flags & (FL_POSIX|FL_BROKEN)) != FL_POSIX)
 278                 return -ENOLCK;
 279
 280         /*
 281          * Flush all pending writes before doing anything
 282          * with locks..
 283          */
 284         status = nfs_wb_all(inode);
 285         if (status < 0)
 286                 return status;
 287
 288         if ((status = nlmclnt_proc(inode, cmd, fl)) < 0)
 289                 return status;
 290         else
 291                 status = 0;
 292
 293         /*
 294          * Make sure we re-validate anything we've got cached.
 295          * This makes locking act as a cache coherency point.
 296          */
 297  out_ok:
 298         NFS_CACHEINV(inode);
 299         return status;
 300 }