WSL2-Linux-Kernel/fs/9p/vfs_addr.c

354 строки
8.2 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 <linux/aio.h>
#include <net/9p/9p.h>
#include <net/9p/client.h>
#include "v9fs.h"
#include "v9fs_vfs.h"
#include "cache.h"
#include "fid.h"
/**
* v9fs_fid_readpage - read an entire page in from 9P
*
* @fid: fid being read
* @page: structure to page
*
*/
static int v9fs_fid_readpage(struct p9_fid *fid, struct page *page)
{
int retval;
loff_t offset;
char *buffer;
struct inode *inode;
inode = page->mapping->host;
p9_debug(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_fid_readn(fid, 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_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)
{
return v9fs_fid_readpage(filp->private_data, page);
}
/**
* 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_debug(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_debug(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 called with zero offset, we should release
* the private state assocated with the page
*/
if (offset == 0)
v9fs_fscache_invalidate_page(page);
}
static int v9fs_vfs_writepage_locked(struct page *page)
{
char *buffer;
int retval, len;
loff_t offset, size;
mm_segment_t old_fs;
struct v9fs_inode *v9inode;
struct inode *inode = page->mapping->host;
v9inode = V9FS_I(inode);
size = i_size_read(inode);
if (page->index == size >> PAGE_CACHE_SHIFT)
len = size & ~PAGE_CACHE_MASK;
else
len = PAGE_CACHE_SIZE;
set_page_writeback(page);
buffer = kmap(page);
offset = page_offset(page);
old_fs = get_fs();
set_fs(get_ds());
/* We should have writeback_fid always set */
BUG_ON(!v9inode->writeback_fid);
retval = v9fs_file_write_internal(inode,
v9inode->writeback_fid,
(__force const char __user *)buffer,
len, &offset, 0);
if (retval > 0)
retval = 0;
set_fs(old_fs);
kunmap(page);
end_page_writeback(page);
return retval;
}
static int v9fs_vfs_writepage(struct page *page, struct writeback_control *wbc)
{
int retval;
retval = v9fs_vfs_writepage_locked(page);
if (retval < 0) {
if (retval == -EAGAIN) {
redirty_page_for_writepage(wbc, page);
retval = 0;
} else {
SetPageError(page);
mapping_set_error(page->mapping, retval);
}
} else
retval = 0;
unlock_page(page);
return retval;
}
/**
* v9fs_launder_page - Writeback a dirty page
* Returns 0 on success.
*/
static int v9fs_launder_page(struct page *page)
{
int retval;
struct inode *inode = page->mapping->host;
v9fs_fscache_wait_on_page_write(inode, page);
if (clear_page_dirty_for_io(page)) {
retval = v9fs_vfs_writepage_locked(page);
if (retval)
return retval;
}
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.
*
*/
static ssize_t
v9fs_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov,
loff_t pos, unsigned long nr_segs)
{
/*
* FIXME
* Now that we do caching with cache mode enabled, We need
* to support direct IO
*/
p9_debug(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;
}
static int v9fs_write_begin(struct file *filp, struct address_space *mapping,
loff_t pos, unsigned len, unsigned flags,
struct page **pagep, void **fsdata)
{
int retval = 0;
struct page *page;
struct v9fs_inode *v9inode;
pgoff_t index = pos >> PAGE_CACHE_SHIFT;
struct inode *inode = mapping->host;
v9inode = V9FS_I(inode);
start:
page = grab_cache_page_write_begin(mapping, index, flags);
if (!page) {
retval = -ENOMEM;
goto out;
}
BUG_ON(!v9inode->writeback_fid);
if (PageUptodate(page))
goto out;
if (len == PAGE_CACHE_SIZE)
goto out;
retval = v9fs_fid_readpage(v9inode->writeback_fid, page);
page_cache_release(page);
if (!retval)
goto start;
out:
*pagep = page;
return retval;
}
static int v9fs_write_end(struct file *filp, struct address_space *mapping,
loff_t pos, unsigned len, unsigned copied,
struct page *page, void *fsdata)
{
loff_t last_pos = pos + copied;
struct inode *inode = page->mapping->host;
if (unlikely(copied < len)) {
/*
* zero out the rest of the area
*/
unsigned from = pos & (PAGE_CACHE_SIZE - 1);
zero_user(page, from + copied, len - copied);
flush_dcache_page(page);
}
if (!PageUptodate(page))
SetPageUptodate(page);
/*
* No need to use i_size_read() here, the i_size
* cannot change under us because we hold the i_mutex.
*/
if (last_pos > inode->i_size) {
inode_add_bytes(inode, last_pos - inode->i_size);
i_size_write(inode, last_pos);
}
set_page_dirty(page);
unlock_page(page);
page_cache_release(page);
return copied;
}
const struct address_space_operations v9fs_addr_operations = {
.readpage = v9fs_vfs_readpage,
.readpages = v9fs_vfs_readpages,
.set_page_dirty = __set_page_dirty_nobuffers,
.writepage = v9fs_vfs_writepage,
.write_begin = v9fs_write_begin,
.write_end = v9fs_write_end,
.releasepage = v9fs_release_page,
.invalidatepage = v9fs_invalidate_page,
.launder_page = v9fs_launder_page,
.direct_IO = v9fs_direct_IO,
};