[deliverable/linux.git] / fs / 9p / vfs_addr.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 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)
{
	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;

	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
 * @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;


	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,
};
Commit	Line	Data
147b31cf EVH	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
42e8c509 EVH	10	* it under the terms of the GNU General Public License version 2
42e8c509 EVH	11	* as published by the Free Software Foundation.
147b31cf EVH	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>
147b31cf	32	#include <linux/inet.h>
147b31cf EVH	33	#include <linux/pagemap.h>
147b31cf EVH	34	#include <linux/idr.h>
e8edc6e0	35	#include <linux/sched.h>
a27bb332	36	#include <linux/aio.h>
bd238fb4 LI	37	#include <net/9p/9p.h>
bd238fb4 LI	38	#include <net/9p/client.h>
147b31cf	39
147b31cf	40	#include "v9fs.h"
147b31cf	41	#include "v9fs_vfs.h"
60e78d2c	42	#include "cache.h"
7263cebe	43	#include "fid.h"
147b31cf EVH	44
147b31cf EVH	45	/**
7263cebe	46	* v9fs_fid_readpage - read an entire page in from 9P
147b31cf	47	*
7263cebe	48	* @fid: fid being read
147b31cf EVH	49	* @page: structure to page
	50	*
	51	*/
7263cebe	52	static int v9fs_fid_readpage(struct p9_fid fid, struct page page)
147b31cf	53	{
bd238fb4 LI	54	int retval;
	55	loff_t offset;
	56	char *buffer;
60e78d2c	57	struct inode *inode;
e03abc0c	58
60e78d2c	59	inode = page->mapping->host;
5d385153	60	p9_debug(P9_DEBUG_VFS, "\n");
60e78d2c AK	61
	62	BUG_ON(!PageLocked(page));
	63
	64	retval = v9fs_readpage_from_fscache(inode, page);
	65	if (retval == 0)
	66	return retval;
	67
147b31cf	68	buffer = kmap(page);
bd238fb4	69	offset = page_offset(page);
147b31cf	70
7263cebe	71	retval = v9fs_fid_readn(fid, buffer, NULL, PAGE_CACHE_SIZE, offset);
60e78d2c AK	72	if (retval < 0) {
60e78d2c AK	73	v9fs_uncache_page(inode, page);
bd238fb4	74	goto done;
60e78d2c	75	}
147b31cf	76
bd238fb4	77	memset(buffer + retval, 0, PAGE_CACHE_SIZE - retval);
147b31cf EVH	78	flush_dcache_page(page);
147b31cf EVH	79	SetPageUptodate(page);
60e78d2c AK	80
60e78d2c AK	81	v9fs_readpage_to_fscache(inode, page);
147b31cf EVH	82	retval = 0;
147b31cf EVH	83
bd238fb4	84	done:
147b31cf EVH	85	kunmap(page);
	86	unlock_page(page);
	87	return retval;
	88	}
	89
7263cebe AK	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
60e78d2c AK	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;
5d385153	120	p9_debug(P9_DEBUG_VFS, "inode: %p file: %p\n", inode, filp);
60e78d2c AK	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);
5d385153	127	p9_debug(P9_DEBUG_VFS, " = %d\n", ret);
60e78d2c AK	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;
60e78d2c AK	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
d47992f8 LC	151	static void v9fs_invalidate_page(struct page *page, unsigned int offset,
d47992f8 LC	152	unsigned int length)
60e78d2c	153	{
7263cebe AK	154	/*
	155	* If called with zero offset, we should release
	156	* the private state assocated with the page
	157	*/
d47992f8	158	if (offset == 0 && length == PAGE_CACHE_SIZE)
60e78d2c AK	159	v9fs_fscache_invalidate_page(page);
	160	}
	161
7263cebe AK	162	static int v9fs_vfs_writepage_locked(struct page *page)
	163	{
	164	char *buffer;
	165	int retval, len;
	166	loff_t offset, size;
	167	mm_segment_t old_fs;
6b39f6d2	168	struct v9fs_inode *v9inode;
7263cebe AK	169	struct inode *inode = page->mapping->host;
7263cebe AK	170
6b39f6d2	171	v9inode = V9FS_I(inode);
7263cebe AK	172	size = i_size_read(inode);
	173	if (page->index == size >> PAGE_CACHE_SHIFT)
	174	len = size & ~PAGE_CACHE_MASK;
	175	else
	176	len = PAGE_CACHE_SIZE;
	177
	178	set_page_writeback(page);
	179
	180	buffer = kmap(page);
	181	offset = page_offset(page);
	182
	183	old_fs = get_fs();
	184	set_fs(get_ds());
6b39f6d2 AK	185	/* We should have writeback_fid always set */
6b39f6d2 AK	186	BUG_ON(!v9inode->writeback_fid);
7263cebe AK	187
7263cebe AK	188	retval = v9fs_file_write_internal(inode,
6b39f6d2	189	v9inode->writeback_fid,
7263cebe AK	190	(__force const char __user *)buffer,
	191	len, &offset, 0);
	192	if (retval > 0)
	193	retval = 0;
	194
	195	set_fs(old_fs);
	196	kunmap(page);
	197	end_page_writeback(page);
	198	return retval;
	199	}
	200
	201	static int v9fs_vfs_writepage(struct page page, struct writeback_control wbc)
	202	{
	203	int retval;
	204
fb89b45c DM	205	p9_debug(P9_DEBUG_VFS, "page %p\n", page);
fb89b45c DM	206
7263cebe AK	207	retval = v9fs_vfs_writepage_locked(page);
	208	if (retval < 0) {
	209	if (retval == -EAGAIN) {
	210	redirty_page_for_writepage(wbc, page);
	211	retval = 0;
	212	} else {
	213	SetPageError(page);
	214	mapping_set_error(page->mapping, retval);
	215	}
	216	} else
	217	retval = 0;
	218
	219	unlock_page(page);
	220	return retval;
	221	}
	222
60e78d2c AK	223	/**
60e78d2c AK	224	* v9fs_launder_page - Writeback a dirty page
60e78d2c AK	225	* Returns 0 on success.
	226	*/
	227
	228	static int v9fs_launder_page(struct page *page)
	229	{
7263cebe	230	int retval;
2efda799	231	struct inode *inode = page->mapping->host;
7263cebe	232
2efda799	233	v9fs_fscache_wait_on_page_write(inode, page);
7263cebe AK	234	if (clear_page_dirty_for_io(page)) {
	235	retval = v9fs_vfs_writepage_locked(page);
	236	if (retval)
	237	return retval;
	238	}
60e78d2c AK	239	return 0;
	240	}
	241
3e24ad2f	242	/**
	243	* v9fs_direct_IO - 9P address space operation for direct I/O
	244	* @rw: direction (read or write)
	245	* @iocb: target I/O control block
	246	* @iov: array of vectors that define I/O buffer
	247	* @pos: offset in file to begin the operation
	248	* @nr_segs: size of iovec array
	249	*
	250	* The presence of v9fs_direct_IO() in the address space ops vector
	251	* allowes open() O_DIRECT flags which would have failed otherwise.
	252	*
	253	* In the non-cached mode, we shunt off direct read and write requests before
	254	* the VFS gets them, so this method should never be called.
	255	*
	256	* Direct IO is not 'yet' supported in the cached mode. Hence when
	257	* this routine is called through generic_file_aio_read(), the read/write fails
	258	* with an error.
	259	*
	260	*/
e959b549 AK	261	static ssize_t
	262	v9fs_direct_IO(int rw, struct kiocb iocb, const struct iovec iov,
	263	loff_t pos, unsigned long nr_segs)
3e24ad2f	264	{
7263cebe AK	265	/*
	266	* FIXME
	267	* Now that we do caching with cache mode enabled, We need
	268	* to support direct IO
	269	*/
5d385153 JP	270	p9_debug(P9_DEBUG_VFS, "v9fs_direct_IO: v9fs_direct_IO (%s) off/no(%lld/%lu) EINVAL\n",
	271	iocb->ki_filp->f_path.dentry->d_name.name,
	272	(long long)pos, nr_segs);
3e24ad2f	273
	274	return -EINVAL;
	275	}
7263cebe AK	276
	277	static int v9fs_write_begin(struct file filp, struct address_space mapping,
	278	loff_t pos, unsigned len, unsigned flags,
	279	struct page pagep, void fsdata)
	280	{
	281	int retval = 0;
	282	struct page *page;
6b39f6d2	283	struct v9fs_inode *v9inode;
7263cebe AK	284	pgoff_t index = pos >> PAGE_CACHE_SHIFT;
	285	struct inode *inode = mapping->host;
	286
fb89b45c DM	287
	288	p9_debug(P9_DEBUG_VFS, "filp %p, mapping %p\n", filp, mapping);
	289
6b39f6d2	290	v9inode = V9FS_I(inode);
7263cebe AK	291	start:
	292	page = grab_cache_page_write_begin(mapping, index, flags);
	293	if (!page) {
	294	retval = -ENOMEM;
	295	goto out;
	296	}
6b39f6d2	297	BUG_ON(!v9inode->writeback_fid);
7263cebe AK	298	if (PageUptodate(page))
	299	goto out;
	300
	301	if (len == PAGE_CACHE_SIZE)
	302	goto out;
	303
6b39f6d2	304	retval = v9fs_fid_readpage(v9inode->writeback_fid, page);
7263cebe AK	305	page_cache_release(page);
	306	if (!retval)
	307	goto start;
	308	out:
	309	*pagep = page;
	310	return retval;
	311	}
	312
	313	static int v9fs_write_end(struct file filp, struct address_space mapping,
	314	loff_t pos, unsigned len, unsigned copied,
	315	struct page page, void fsdata)
	316	{
	317	loff_t last_pos = pos + copied;
	318	struct inode *inode = page->mapping->host;
	319
fb89b45c DM	320	p9_debug(P9_DEBUG_VFS, "filp %p, mapping %p\n", filp, mapping);
fb89b45c DM	321
7263cebe AK	322	if (unlikely(copied < len)) {
	323	/*
	324	* zero out the rest of the area
	325	*/
	326	unsigned from = pos & (PAGE_CACHE_SIZE - 1);
	327
	328	zero_user(page, from + copied, len - copied);
	329	flush_dcache_page(page);
	330	}
	331
	332	if (!PageUptodate(page))
	333	SetPageUptodate(page);
	334	/*
	335	* No need to use i_size_read() here, the i_size
	336	* cannot change under us because we hold the i_mutex.
	337	*/
	338	if (last_pos > inode->i_size) {
	339	inode_add_bytes(inode, last_pos - inode->i_size);
	340	i_size_write(inode, last_pos);
	341	}
	342	set_page_dirty(page);
	343	unlock_page(page);
	344	page_cache_release(page);
	345
	346	return copied;
	347	}
	348
	349
f5e54d6e	350	const struct address_space_operations v9fs_addr_operations = {
7263cebe AK	351	.readpage = v9fs_vfs_readpage,
	352	.readpages = v9fs_vfs_readpages,
	353	.set_page_dirty = __set_page_dirty_nobuffers,
	354	.writepage = v9fs_vfs_writepage,
	355	.write_begin = v9fs_write_begin,
	356	.write_end = v9fs_write_end,
	357	.releasepage = v9fs_release_page,
	358	.invalidatepage = v9fs_invalidate_page,
	359	.launder_page = v9fs_launder_page,
	360	.direct_IO = v9fs_direct_IO,
147b31cf	361	};