fs/9p/vfs_addr.c - kernel/lockdown - Git at Google

 /*
  *  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/uio.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)
 {
 	struct inode *inode = page->mapping->host;
 	struct bio_vec bvec = {.bv_page = page, .bv_len = PAGE_SIZE};
 	struct iov_iter to;
 	int retval, err;

 	p9_debug(P9_DEBUG_VFS, "\n");

 	BUG_ON(!PageLocked(page));

 	retval = v9fs_readpage_from_fscache(inode, page);
 	if (retval == 0)
 		return retval;

 	iov_iter_bvec(&to, ITER_BVEC | READ, &bvec, 1, PAGE_SIZE);

 	retval = p9_client_read(fid, page_offset(page), &to, &err);
 	if (err) {
 		v9fs_uncache_page(inode, page);
 		retval = err;
 		goto done;
 	}

 	zero_user(page, retval, PAGE_SIZE - retval);
 	flush_dcache_page(page);
 	SetPageUptodate(page);

 	v9fs_readpage_to_fscache(inode, page);
 	retval = 0;

 done:
 	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 int offset,
 				 unsigned int length)
 {
 	/*
 	 * If called with zero offset, we should release
 	 * the private state assocated with the page
 	 */
 	if (offset == 0 && length == PAGE_CACHE_SIZE)
 		v9fs_fscache_invalidate_page(page);
 }

 static int v9fs_vfs_writepage_locked(struct page *page)
 {
 	struct inode *inode = page->mapping->host;
 	struct v9fs_inode *v9inode = V9FS_I(inode);
 	loff_t size = i_size_read(inode);
 	struct iov_iter from;
 	struct bio_vec bvec;
 	int err, len;

 	if (page->index == size >> PAGE_CACHE_SHIFT)
 		len = size & ~PAGE_CACHE_MASK;
 	else
 		len = PAGE_CACHE_SIZE;

 	bvec.bv_page = page;
 	bvec.bv_offset = 0;
 	bvec.bv_len = len;
 	iov_iter_bvec(&from, ITER_BVEC | WRITE, &bvec, 1, len);

 	/* We should have writeback_fid always set */
 	BUG_ON(!v9inode->writeback_fid);

 	set_page_writeback(page);

 	p9_client_write(v9inode->writeback_fid, page_offset(page), &from, &err);

 	end_page_writeback(page);
 	return err;
 }

 static int v9fs_vfs_writepage(struct page *page, struct writeback_control *wbc)
 {
 	int retval;

 	p9_debug(P9_DEBUG_VFS, "page %p\n", page);

 	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
  * @iocb: target I/O control block
  * @pos: offset in file to begin the operation
  *
  * 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(struct kiocb *iocb, struct iov_iter *iter, loff_t pos)
 {
 	struct file *file = iocb->ki_filp;
 	ssize_t n;
 	int err = 0;
 	if (iov_iter_rw(iter) == WRITE) {
 		n = p9_client_write(file->private_data, pos, iter, &err);
 		if (n) {
 			struct inode *inode = file_inode(file);
 			loff_t i_size = i_size_read(inode);
 			if (pos + n > i_size)
 				inode_add_bytes(inode, pos + n - i_size);
 		}
 	} else {
 		n = p9_client_read(file->private_data, pos, iter, &err);
 	}
 	return n ? n : err;
 }

 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;


 	p9_debug(P9_DEBUG_VFS, "filp %p, mapping %p\n", filp, mapping);

 	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;

 	p9_debug(P9_DEBUG_VFS, "filp %p, mapping %p\n", filp, mapping);

 	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,
 };
	/*
	* 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/uio.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)
	{
	struct inode *inode = page->mapping->host;
	struct bio_vec bvec = {.bv_page = page, .bv_len = PAGE_SIZE};
	struct iov_iter to;
	int retval, err;

	p9_debug(P9_DEBUG_VFS, "\n");

	BUG_ON(!PageLocked(page));

	retval = v9fs_readpage_from_fscache(inode, page);
	if (retval == 0)
	return retval;

	iov_iter_bvec(&to, ITER_BVEC \| READ, &bvec, 1, PAGE_SIZE);

	retval = p9_client_read(fid, page_offset(page), &to, &err);
	if (err) {
	v9fs_uncache_page(inode, page);
	retval = err;
	goto done;
	}

	zero_user(page, retval, PAGE_SIZE - retval);
	flush_dcache_page(page);
	SetPageUptodate(page);

	v9fs_readpage_to_fscache(inode, page);
	retval = 0;

	done:
	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 int offset,
	unsigned int length)
	{
	/*
	* If called with zero offset, we should release
	* the private state assocated with the page
	*/
	if (offset == 0 && length == PAGE_CACHE_SIZE)
	v9fs_fscache_invalidate_page(page);
	}

	static int v9fs_vfs_writepage_locked(struct page *page)
	{
	struct inode *inode = page->mapping->host;
	struct v9fs_inode *v9inode = V9FS_I(inode);
	loff_t size = i_size_read(inode);
	struct iov_iter from;
	struct bio_vec bvec;
	int err, len;

	if (page->index == size >> PAGE_CACHE_SHIFT)
	len = size & ~PAGE_CACHE_MASK;
	else
	len = PAGE_CACHE_SIZE;

	bvec.bv_page = page;
	bvec.bv_offset = 0;
	bvec.bv_len = len;
	iov_iter_bvec(&from, ITER_BVEC \| WRITE, &bvec, 1, len);

	/* We should have writeback_fid always set */
	BUG_ON(!v9inode->writeback_fid);

	set_page_writeback(page);

	p9_client_write(v9inode->writeback_fid, page_offset(page), &from, &err);

	end_page_writeback(page);
	return err;
	}

	static int v9fs_vfs_writepage(struct page page, struct writeback_control wbc)
	{
	int retval;

	p9_debug(P9_DEBUG_VFS, "page %p\n", page);

	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
	* @iocb: target I/O control block
	* @pos: offset in file to begin the operation
	*
	* 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(struct kiocb iocb, struct iov_iter iter, loff_t pos)
	{
	struct file *file = iocb->ki_filp;
	ssize_t n;
	int err = 0;
	if (iov_iter_rw(iter) == WRITE) {
	n = p9_client_write(file->private_data, pos, iter, &err);
	if (n) {
	struct inode *inode = file_inode(file);
	loff_t i_size = i_size_read(inode);
	if (pos + n > i_size)
	inode_add_bytes(inode, pos + n - i_size);
	}
	} else {
	n = p9_client_read(file->private_data, pos, iter, &err);
	}
	return n ? n : err;
	}

	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;


	p9_debug(P9_DEBUG_VFS, "filp %p, mapping %p\n", filp, mapping);

	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;

	p9_debug(P9_DEBUG_VFS, "filp %p, mapping %p\n", filp, mapping);

	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,
	};