fs/9p/vfs_addr.c

   1 /*
   2  *  linux/fs/9p/vfs_addr.c
   3  *
   4  * This file contians vfs address (mmap) ops for 9P2000.
   5  *
   6  *  Copyright (C) 2005 by Eric Van Hensbergen <ericvh@gmail.com>
   7  *  Copyright (C) 2002 by Ron Minnich <rminnich@lanl.gov>
   8  *
   9  *  This program is free software; you can redistribute it and/or modify
  10  *  it under the terms of the GNU General Public License version 2
  11  *  as published by the Free Software Foundation.
  12  *
  13  *  This program is distributed in the hope that it will be useful,
  14  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16  *  GNU General Public License for more details.
  17  *
  18  *  You should have received a copy of the GNU General Public License
  19  *  along with this program; if not, write to:
  20  *  Free Software Foundation
  21  *  51 Franklin Street, Fifth Floor
  22  *  Boston, MA  02111-1301  USA
  23  *
  24  */
  25
  26 #include <linux/module.h>
  27 #include <linux/errno.h>
  28 #include <linux/fs.h>
  29 #include <linux/file.h>
  30 #include <linux/stat.h>
  31 #include <linux/string.h>
  32 #include <linux/inet.h>
  33 #include <linux/pagemap.h>
  34 #include <linux/idr.h>
  35 #include <linux/sched.h>
  36 #include <net/9p/9p.h>
  37 #include <net/9p/client.h>
  38
  39 #include "v9fs.h"
  40 #include "v9fs_vfs.h"
  41 #include "cache.h"
  42 #include "fid.h"
  43
  44 /**
  45  * v9fs_fid_readpage - read an entire page in from 9P
  46  *
  47  * @fid: fid being read
  48  * @page: structure to page
  49  *
  50  */
  51 static int v9fs_fid_readpage(struct p9_fid *fid, struct page *page)
  52 {
  53         int retval;
  54         loff_t offset;
  55         char *buffer;
  56         struct inode *inode;
  57
  58         inode = page->mapping->host;
  59         P9_DPRINTK(P9_DEBUG_VFS, "\n");
  60
  61         BUG_ON(!PageLocked(page));
  62
  63         retval = v9fs_readpage_from_fscache(inode, page);
  64         if (retval == 0)
  65                 return retval;
  66
  67         buffer = kmap(page);
  68         offset = page_offset(page);
  69
  70         retval = v9fs_fid_readn(fid, buffer, NULL, PAGE_CACHE_SIZE, offset);
  71         if (retval < 0) {
  72                 v9fs_uncache_page(inode, page);
  73                 goto done;
  74         }
  75
  76         memset(buffer + retval, 0, PAGE_CACHE_SIZE - retval);
  77         flush_dcache_page(page);
  78         SetPageUptodate(page);
  79
  80         v9fs_readpage_to_fscache(inode, page);
  81         retval = 0;
  82
  83 done:
  84         kunmap(page);
  85         unlock_page(page);
  86         return retval;
  87 }
  88
  89 /**
  90  * v9fs_vfs_readpage - read an entire page in from 9P
  91  *
  92  * @filp: file being read
  93  * @page: structure to page
  94  *
  95  */
  96
  97 static int v9fs_vfs_readpage(struct file *filp, struct page *page)
  98 {
  99         return v9fs_fid_readpage(filp->private_data, page);
 100 }
 101
 102 /**
 103  * v9fs_vfs_readpages - read a set of pages from 9P
 104  *
 105  * @filp: file being read
 106  * @mapping: the address space
 107  * @pages: list of pages to read
 108  * @nr_pages: count of pages to read
 109  *
 110  */
 111
 112 static int v9fs_vfs_readpages(struct file *filp, struct address_space *mapping,
 113                              struct list_head *pages, unsigned nr_pages)
 114 {
 115         int ret = 0;
 116         struct inode *inode;
 117
 118         inode = mapping->host;
 119         P9_DPRINTK(P9_DEBUG_VFS, "inode: %p file: %p\n", inode, filp);
 120
 121         ret = v9fs_readpages_from_fscache(inode, mapping, pages, &nr_pages);
 122         if (ret == 0)
 123                 return ret;
 124
 125         ret = read_cache_pages(mapping, pages, (void *)v9fs_vfs_readpage, filp);
 126         P9_DPRINTK(P9_DEBUG_VFS, "  = %d\n", ret);
 127         return ret;
 128 }
 129
 130 /**
 131  * v9fs_release_page - release the private state associated with a page
 132  *
 133  * Returns 1 if the page can be released, false otherwise.
 134  */
 135
 136 static int v9fs_release_page(struct page *page, gfp_t gfp)
 137 {
 138         if (PagePrivate(page))
 139                 return 0;
 140         return v9fs_fscache_release_page(page, gfp);
 141 }
 142
 143 /**
 144  * v9fs_invalidate_page - Invalidate a page completely or partially
 145  *
 146  * @page: structure to page
 147  * @offset: offset in the page
 148  */
 149
 150 static void v9fs_invalidate_page(struct page *page, unsigned long offset)
 151 {
 152         /*
 153          * If called with zero offset, we should release
 154          * the private state assocated with the page
 155          */
 156         if (offset == 0)
 157                 v9fs_fscache_invalidate_page(page);
 158 }
 159
 160 static int v9fs_vfs_writepage_locked(struct page *page)
 161 {
 162         char *buffer;
 163         int retval, len;
 164         loff_t offset, size;
 165         mm_segment_t old_fs;
 166         struct v9fs_inode *v9inode;
 167         struct inode *inode = page->mapping->host;
 168
 169         v9inode = V9FS_I(inode);
 170         size = i_size_read(inode);
 171         if (page->index == size >> PAGE_CACHE_SHIFT)
 172                 len = size & ~PAGE_CACHE_MASK;
 173         else
 174                 len = PAGE_CACHE_SIZE;
 175
 176         set_page_writeback(page);
 177
 178         buffer = kmap(page);
 179         offset = page_offset(page);
 180
 181         old_fs = get_fs();
 182         set_fs(get_ds());
 183         /* We should have writeback_fid always set */
 184         BUG_ON(!v9inode->writeback_fid);
 185
 186         retval = v9fs_file_write_internal(inode,
 187                                           v9inode->writeback_fid,
 188                                           (__force const char __user *)buffer,
 189                                           len, &offset, 0);
 190         if (retval > 0)
 191                 retval = 0;
 192
 193         set_fs(old_fs);
 194         kunmap(page);
 195         end_page_writeback(page);
 196         return retval;
 197 }
 198
 199 static int v9fs_vfs_writepage(struct page *page, struct writeback_control *wbc)
 200 {
 201         int retval;
 202
 203         retval = v9fs_vfs_writepage_locked(page);
 204         if (retval < 0) {
 205                 if (retval == -EAGAIN) {
 206                         redirty_page_for_writepage(wbc, page);
 207                         retval = 0;
 208                 } else {
 209                         SetPageError(page);
 210                         mapping_set_error(page->mapping, retval);
 211                 }
 212         } else
 213                 retval = 0;
 214
 215         unlock_page(page);
 216         return retval;
 217 }
 218
 219 /**
 220  * v9fs_launder_page - Writeback a dirty page
 221  * Returns 0 on success.
 222  */
 223
 224 static int v9fs_launder_page(struct page *page)
 225 {
 226         int retval;
 227         struct inode *inode = page->mapping->host;
 228
 229         v9fs_fscache_wait_on_page_write(inode, page);
 230         if (clear_page_dirty_for_io(page)) {
 231                 retval = v9fs_vfs_writepage_locked(page);
 232                 if (retval)
 233                         return retval;
 234         }
 235         return 0;
 236 }
 237
 238 /**
 239  * v9fs_direct_IO - 9P address space operation for direct I/O
 240  * @rw: direction (read or write)
 241  * @iocb: target I/O control block
 242  * @iov: array of vectors that define I/O buffer
 243  * @pos: offset in file to begin the operation
 244  * @nr_segs: size of iovec array
 245  *
 246  * The presence of v9fs_direct_IO() in the address space ops vector
 247  * allowes open() O_DIRECT flags which would have failed otherwise.
 248  *
 249  * In the non-cached mode, we shunt off direct read and write requests before
 250  * the VFS gets them, so this method should never be called.
 251  *
 252  * Direct IO is not 'yet' supported in the cached mode. Hence when
 253  * this routine is called through generic_file_aio_read(), the read/write fails
 254  * with an error.
 255  *
 256  */
 257 static ssize_t
 258 v9fs_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov,
 259                loff_t pos, unsigned long nr_segs)
 260 {
 261         /*
 262          * FIXME
 263          * Now that we do caching with cache mode enabled, We need
 264          * to support direct IO
 265          */
 266         P9_DPRINTK(P9_DEBUG_VFS, "v9fs_direct_IO: v9fs_direct_IO (%s) "
 267                         "off/no(%lld/%lu) EINVAL\n",
 268                         iocb->ki_filp->f_path.dentry->d_name.name,
 269                         (long long) pos, nr_segs);
 270
 271         return -EINVAL;
 272 }
 273
 274 static int v9fs_write_begin(struct file *filp, struct address_space *mapping,
 275                             loff_t pos, unsigned len, unsigned flags,
 276                             struct page **pagep, void **fsdata)
 277 {
 278         int retval = 0;
 279         struct page *page;
 280         struct v9fs_inode *v9inode;
 281         pgoff_t index = pos >> PAGE_CACHE_SHIFT;
 282         struct inode *inode = mapping->host;
 283
 284         v9inode = V9FS_I(inode);
 285 start:
 286         page = grab_cache_page_write_begin(mapping, index, flags);
 287         if (!page) {
 288                 retval = -ENOMEM;
 289                 goto out;
 290         }
 291         BUG_ON(!v9inode->writeback_fid);
 292         if (PageUptodate(page))
 293                 goto out;
 294
 295         if (len == PAGE_CACHE_SIZE)
 296                 goto out;
 297
 298         retval = v9fs_fid_readpage(v9inode->writeback_fid, page);
 299         page_cache_release(page);
 300         if (!retval)
 301                 goto start;
 302 out:
 303         *pagep = page;
 304         return retval;
 305 }
 306
 307 static int v9fs_write_end(struct file *filp, struct address_space *mapping,
 308                           loff_t pos, unsigned len, unsigned copied,
 309                           struct page *page, void *fsdata)
 310 {
 311         loff_t last_pos = pos + copied;
 312         struct inode *inode = page->mapping->host;
 313
 314         if (unlikely(copied < len)) {
 315                 /*
 316                  * zero out the rest of the area
 317                  */
 318                 unsigned from = pos & (PAGE_CACHE_SIZE - 1);
 319
 320                 zero_user(page, from + copied, len - copied);
 321                 flush_dcache_page(page);
 322         }
 323
 324         if (!PageUptodate(page))
 325                 SetPageUptodate(page);
 326         /*
 327          * No need to use i_size_read() here, the i_size
 328          * cannot change under us because we hold the i_mutex.
 329          */
 330         if (last_pos > inode->i_size) {
 331                 inode_add_bytes(inode, last_pos - inode->i_size);
 332                 i_size_write(inode, last_pos);
 333         }
 334         set_page_dirty(page);
 335         unlock_page(page);
 336         page_cache_release(page);
 337
 338         return copied;
 339 }
 340
 341
 342 const struct address_space_operations v9fs_addr_operations = {
 343         .readpage = v9fs_vfs_readpage,
 344         .readpages = v9fs_vfs_readpages,
 345         .set_page_dirty = __set_page_dirty_nobuffers,
 346         .writepage = v9fs_vfs_writepage,
 347         .write_begin = v9fs_write_begin,
 348         .write_end = v9fs_write_end,
 349         .releasepage = v9fs_release_page,
 350         .invalidatepage = v9fs_invalidate_page,
 351         .launder_page = v9fs_launder_page,
 352         .direct_IO = v9fs_direct_IO,
 353 };