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
  43 /**
  44  * v9fs_vfs_readpage - read an entire page in from 9P
  45  *
  46  * @filp: file being read
  47  * @page: structure to page
  48  *
  49  */
  50
  51 static int v9fs_vfs_readpage(struct file *filp, 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_file_readn(filp, 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_readpages - read a set of pages from 9P
  91  *
  92  * @filp: file being read
  93  * @mapping: the address space
  94  * @pages: list of pages to read
  95  * @nr_pages: count of pages to read
  96  *
  97  */
  98
  99 static int v9fs_vfs_readpages(struct file *filp, struct address_space *mapping,
 100                              struct list_head *pages, unsigned nr_pages)
 101 {
 102         int ret = 0;
 103         struct inode *inode;
 104
 105         inode = mapping->host;
 106         P9_DPRINTK(P9_DEBUG_VFS, "inode: %p file: %p\n", inode, filp);
 107
 108         ret = v9fs_readpages_from_fscache(inode, mapping, pages, &nr_pages);
 109         if (ret == 0)
 110                 return ret;
 111
 112         ret = read_cache_pages(mapping, pages, (void *)v9fs_vfs_readpage, filp);
 113         P9_DPRINTK(P9_DEBUG_VFS, "  = %d\n", ret);
 114         return ret;
 115 }
 116
 117 /**
 118  * v9fs_release_page - release the private state associated with a page
 119  *
 120  * Returns 1 if the page can be released, false otherwise.
 121  */
 122
 123 static int v9fs_release_page(struct page *page, gfp_t gfp)
 124 {
 125         if (PagePrivate(page))
 126                 return 0;
 127
 128         return v9fs_fscache_release_page(page, gfp);
 129 }
 130
 131 /**
 132  * v9fs_invalidate_page - Invalidate a page completely or partially
 133  *
 134  * @page: structure to page
 135  * @offset: offset in the page
 136  */
 137
 138 static void v9fs_invalidate_page(struct page *page, unsigned long offset)
 139 {
 140         if (offset == 0)
 141                 v9fs_fscache_invalidate_page(page);
 142 }
 143
 144 /**
 145  * v9fs_launder_page - Writeback a dirty page
 146  * Since the writes go directly to the server, we simply return a 0
 147  * here to indicate success.
 148  *
 149  * Returns 0 on success.
 150  */
 151
 152 static int v9fs_launder_page(struct page *page)
 153 {
 154         return 0;
 155 }
 156
 157 /**
 158  * v9fs_direct_IO - 9P address space operation for direct I/O
 159  * @rw: direction (read or write)
 160  * @iocb: target I/O control block
 161  * @iov: array of vectors that define I/O buffer
 162  * @pos: offset in file to begin the operation
 163  * @nr_segs: size of iovec array
 164  *
 165  * The presence of v9fs_direct_IO() in the address space ops vector
 166  * allowes open() O_DIRECT flags which would have failed otherwise.
 167  *
 168  * In the non-cached mode, we shunt off direct read and write requests before
 169  * the VFS gets them, so this method should never be called.
 170  *
 171  * Direct IO is not 'yet' supported in the cached mode. Hence when
 172  * this routine is called through generic_file_aio_read(), the read/write fails
 173  * with an error.
 174  *
 175  */
 176 ssize_t v9fs_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov,
 177                 loff_t pos, unsigned long nr_segs)
 178 {
 179         P9_DPRINTK(P9_DEBUG_VFS, "v9fs_direct_IO: v9fs_direct_IO (%s) "
 180                         "off/no(%lld/%lu) EINVAL\n",
 181                         iocb->ki_filp->f_path.dentry->d_name.name,
 182                         (long long) pos, nr_segs);
 183
 184         return -EINVAL;
 185 }
 186 const struct address_space_operations v9fs_addr_operations = {
 187       .readpage = v9fs_vfs_readpage,
 188       .readpages = v9fs_vfs_readpages,
 189       .releasepage = v9fs_release_page,
 190       .invalidatepage = v9fs_invalidate_page,
 191       .launder_page = v9fs_launder_page,
 192       .direct_IO = v9fs_direct_IO,
 193 };