linux/fs/9p/vfs_addr.c
jvrao 3e24ad2ff9 9p: Add a Direct IO support for non-cached operations.
The presence of v9fs_direct_IO() in the address space ops vector
allowes open() O_DIRECT flags which would have failed otherwise.

In the non-cached mode, we shunt off direct read and write requests before
the VFS gets them, so this method should never be called.

Direct IO is not 'yet' supported in the cached mode. Hence when
this routine is called through generic_file_aio_read(), the read/write fails
with an error.

Signed-off-by: Venkateswararao Jujjuri <jvrao@linux.vnet.ibm.com>
Signed-off-by: Eric Van Hensbergen <ericvh@gmail.com>
2010-10-28 09:08:45 -05:00

194 lines
4.8 KiB
C

/*
* linux/fs/9p/vfs_addr.c
*
* This file contians vfs address (mmap) ops for 9P2000.
*
* Copyright (C) 2005 by Eric Van Hensbergen <ericvh@gmail.com>
* Copyright (C) 2002 by Ron Minnich <rminnich@lanl.gov>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2
* as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to:
* Free Software Foundation
* 51 Franklin Street, Fifth Floor
* Boston, MA 02111-1301 USA
*
*/
#include <linux/module.h>
#include <linux/errno.h>
#include <linux/fs.h>
#include <linux/file.h>
#include <linux/stat.h>
#include <linux/string.h>
#include <linux/inet.h>
#include <linux/pagemap.h>
#include <linux/idr.h>
#include <linux/sched.h>
#include <net/9p/9p.h>
#include <net/9p/client.h>
#include "v9fs.h"
#include "v9fs_vfs.h"
#include "cache.h"
/**
* v9fs_vfs_readpage - read an entire page in from 9P
*
* @filp: file being read
* @page: structure to page
*
*/
static int v9fs_vfs_readpage(struct file *filp, struct page *page)
{
int retval;
loff_t offset;
char *buffer;
struct inode *inode;
inode = page->mapping->host;
P9_DPRINTK(P9_DEBUG_VFS, "\n");
BUG_ON(!PageLocked(page));
retval = v9fs_readpage_from_fscache(inode, page);
if (retval == 0)
return retval;
buffer = kmap(page);
offset = page_offset(page);
retval = v9fs_file_readn(filp, buffer, NULL, PAGE_CACHE_SIZE, offset);
if (retval < 0) {
v9fs_uncache_page(inode, page);
goto done;
}
memset(buffer + retval, 0, PAGE_CACHE_SIZE - retval);
flush_dcache_page(page);
SetPageUptodate(page);
v9fs_readpage_to_fscache(inode, page);
retval = 0;
done:
kunmap(page);
unlock_page(page);
return retval;
}
/**
* v9fs_vfs_readpages - read a set of pages from 9P
*
* @filp: file being read
* @mapping: the address space
* @pages: list of pages to read
* @nr_pages: count of pages to read
*
*/
static int v9fs_vfs_readpages(struct file *filp, struct address_space *mapping,
struct list_head *pages, unsigned nr_pages)
{
int ret = 0;
struct inode *inode;
inode = mapping->host;
P9_DPRINTK(P9_DEBUG_VFS, "inode: %p file: %p\n", inode, filp);
ret = v9fs_readpages_from_fscache(inode, mapping, pages, &nr_pages);
if (ret == 0)
return ret;
ret = read_cache_pages(mapping, pages, (void *)v9fs_vfs_readpage, filp);
P9_DPRINTK(P9_DEBUG_VFS, " = %d\n", ret);
return ret;
}
/**
* v9fs_release_page - release the private state associated with a page
*
* Returns 1 if the page can be released, false otherwise.
*/
static int v9fs_release_page(struct page *page, gfp_t gfp)
{
if (PagePrivate(page))
return 0;
return v9fs_fscache_release_page(page, gfp);
}
/**
* v9fs_invalidate_page - Invalidate a page completely or partially
*
* @page: structure to page
* @offset: offset in the page
*/
static void v9fs_invalidate_page(struct page *page, unsigned long offset)
{
if (offset == 0)
v9fs_fscache_invalidate_page(page);
}
/**
* v9fs_launder_page - Writeback a dirty page
* Since the writes go directly to the server, we simply return a 0
* here to indicate success.
*
* Returns 0 on success.
*/
static int v9fs_launder_page(struct page *page)
{
return 0;
}
/**
* v9fs_direct_IO - 9P address space operation for direct I/O
* @rw: direction (read or write)
* @iocb: target I/O control block
* @iov: array of vectors that define I/O buffer
* @pos: offset in file to begin the operation
* @nr_segs: size of iovec array
*
* The presence of v9fs_direct_IO() in the address space ops vector
* allowes open() O_DIRECT flags which would have failed otherwise.
*
* In the non-cached mode, we shunt off direct read and write requests before
* the VFS gets them, so this method should never be called.
*
* Direct IO is not 'yet' supported in the cached mode. Hence when
* this routine is called through generic_file_aio_read(), the read/write fails
* with an error.
*
*/
ssize_t v9fs_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov,
loff_t pos, unsigned long nr_segs)
{
P9_DPRINTK(P9_DEBUG_VFS, "v9fs_direct_IO: v9fs_direct_IO (%s) "
"off/no(%lld/%lu) EINVAL\n",
iocb->ki_filp->f_path.dentry->d_name.name,
(long long) pos, nr_segs);
return -EINVAL;
}
const struct address_space_operations v9fs_addr_operations = {
.readpage = v9fs_vfs_readpage,
.readpages = v9fs_vfs_readpages,
.releasepage = v9fs_release_page,
.invalidatepage = v9fs_invalidate_page,
.launder_page = v9fs_launder_page,
.direct_IO = v9fs_direct_IO,
};