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 <linux/aio.h>
  37 #include <net/9p/9p.h>
  38 #include <net/9p/client.h>
  39
  40 #include "v9fs.h"
  41 #include "v9fs_vfs.h"
  42 #include "cache.h"
  43 #include "fid.h"
  44
  45 /**
  46  * v9fs_fid_readpage - read an entire page in from 9P
  47  *
  48  * @fid: fid being read
  49  * @page: structure to page
  50  *
  51  */
  52 static int v9fs_fid_readpage(struct p9_fid *fid, struct page *page)
  53 {
  54         int retval;
  55         loff_t offset;
  56         char *buffer;
  57         struct inode *inode;
  58
  59         inode = page->mapping->host;
  60         p9_debug(P9_DEBUG_VFS, "\n");
  61
  62         BUG_ON(!PageLocked(page));
  63
  64         retval = v9fs_readpage_from_fscache(inode, page);
  65         if (retval == 0)
  66                 return retval;
  67
  68         buffer = kmap(page);
  69         offset = page_offset(page);
  70
  71         retval = v9fs_fid_readn(fid, buffer, NULL, PAGE_CACHE_SIZE, offset);
  72         if (retval < 0) {
  73                 v9fs_uncache_page(inode, page);
  74                 goto done;
  75         }
  76
  77         memset(buffer + retval, 0, PAGE_CACHE_SIZE - retval);
  78         flush_dcache_page(page);
  79         SetPageUptodate(page);
  80
  81         v9fs_readpage_to_fscache(inode, page);
  82         retval = 0;
  83
  84 done:
  85         kunmap(page);
  86         unlock_page(page);
  87         return retval;
  88 }
  89
  90 /**
  91  * v9fs_vfs_readpage - read an entire page in from 9P
  92  *
  93  * @filp: file being read
  94  * @page: structure to page
  95  *
  96  */
  97
  98 static int v9fs_vfs_readpage(struct file *filp, struct page *page)
  99 {
 100         return v9fs_fid_readpage(filp->private_data, page);
 101 }
 102
 103 /**
 104  * v9fs_vfs_readpages - read a set of pages from 9P
 105  *
 106  * @filp: file being read
 107  * @mapping: the address space
 108  * @pages: list of pages to read
 109  * @nr_pages: count of pages to read
 110  *
 111  */
 112
 113 static int v9fs_vfs_readpages(struct file *filp, struct address_space *mapping,
 114                              struct list_head *pages, unsigned nr_pages)
 115 {
 116         int ret = 0;
 117         struct inode *inode;
 118
 119         inode = mapping->host;
 120         p9_debug(P9_DEBUG_VFS, "inode: %p file: %p\n", inode, filp);
 121
 122         ret = v9fs_readpages_from_fscache(inode, mapping, pages, &nr_pages);
 123         if (ret == 0)
 124                 return ret;
 125
 126         ret = read_cache_pages(mapping, pages, (void *)v9fs_vfs_readpage, filp);
 127         p9_debug(P9_DEBUG_VFS, "  = %d\n", ret);
 128         return ret;
 129 }
 130
 131 /**
 132  * v9fs_release_page - release the private state associated with a page
 133  *
 134  * Returns 1 if the page can be released, false otherwise.
 135  */
 136
 137 static int v9fs_release_page(struct page *page, gfp_t gfp)
 138 {
 139         if (PagePrivate(page))
 140                 return 0;
 141         return v9fs_fscache_release_page(page, gfp);
 142 }
 143
 144 /**
 145  * v9fs_invalidate_page - Invalidate a page completely or partially
 146  *
 147  * @page: structure to page
 148  * @offset: offset in the page
 149  */
 150
 151 static void v9fs_invalidate_page(struct page *page, unsigned long offset)
 152 {
 153         /*
 154          * If called with zero offset, we should release
 155          * the private state assocated with the page
 156          */
 157         if (offset == 0)
 158                 v9fs_fscache_invalidate_page(page);
 159 }
 160
 161 static int v9fs_vfs_writepage_locked(struct page *page)
 162 {
 163         char *buffer;
 164         int retval, len;
 165         loff_t offset, size;
 166         mm_segment_t old_fs;
 167         struct v9fs_inode *v9inode;
 168         struct inode *inode = page->mapping->host;
 169
 170         v9inode = V9FS_I(inode);
 171         size = i_size_read(inode);
 172         if (page->index == size >> PAGE_CACHE_SHIFT)
 173                 len = size & ~PAGE_CACHE_MASK;
 174         else
 175                 len = PAGE_CACHE_SIZE;
 176
 177         set_page_writeback(page);
 178
 179         buffer = kmap(page);
 180         offset = page_offset(page);
 181
 182         old_fs = get_fs();
 183         set_fs(get_ds());
 184         /* We should have writeback_fid always set */
 185         BUG_ON(!v9inode->writeback_fid);
 186
 187         retval = v9fs_file_write_internal(inode,
 188                                           v9inode->writeback_fid,
 189                                           (__force const char __user *)buffer,
 190                                           len, &offset, 0);
 191         if (retval > 0)
 192                 retval = 0;
 193
 194         set_fs(old_fs);
 195         kunmap(page);
 196         end_page_writeback(page);
 197         return retval;
 198 }
 199
 200 static int v9fs_vfs_writepage(struct page *page, struct writeback_control *wbc)
 201 {
 202         int retval;
 203
 204         retval = v9fs_vfs_writepage_locked(page);
 205         if (retval < 0) {
 206                 if (retval == -EAGAIN) {
 207                         redirty_page_for_writepage(wbc, page);
 208                         retval = 0;
 209                 } else {
 210                         SetPageError(page);
 211                         mapping_set_error(page->mapping, retval);
 212                 }
 213         } else
 214                 retval = 0;
 215
 216         unlock_page(page);
 217         return retval;
 218 }
 219
 220 /**
 221  * v9fs_launder_page - Writeback a dirty page
 222  * Returns 0 on success.
 223  */
 224
 225 static int v9fs_launder_page(struct page *page)
 226 {
 227         int retval;
 228         struct inode *inode = page->mapping->host;
 229
 230         v9fs_fscache_wait_on_page_write(inode, page);
 231         if (clear_page_dirty_for_io(page)) {
 232                 retval = v9fs_vfs_writepage_locked(page);
 233                 if (retval)
 234                         return retval;
 235         }
 236         return 0;
 237 }
 238
 239 /**
 240  * v9fs_direct_IO - 9P address space operation for direct I/O
 241  * @rw: direction (read or write)
 242  * @iocb: target I/O control block
 243  * @iov: array of vectors that define I/O buffer
 244  * @pos: offset in file to begin the operation
 245  * @nr_segs: size of iovec array
 246  *
 247  * The presence of v9fs_direct_IO() in the address space ops vector
 248  * allowes open() O_DIRECT flags which would have failed otherwise.
 249  *
 250  * In the non-cached mode, we shunt off direct read and write requests before
 251  * the VFS gets them, so this method should never be called.
 252  *
 253  * Direct IO is not 'yet' supported in the cached mode. Hence when
 254  * this routine is called through generic_file_aio_read(), the read/write fails
 255  * with an error.
 256  *
 257  */
 258 static ssize_t
 259 v9fs_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov,
 260                loff_t pos, unsigned long nr_segs)
 261 {
 262         /*
 263          * FIXME
 264          * Now that we do caching with cache mode enabled, We need
 265          * to support direct IO
 266          */
 267         p9_debug(P9_DEBUG_VFS, "v9fs_direct_IO: v9fs_direct_IO (%s) 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 };