linux/fs/9p/vfs_addr.c
Lukas Czerner d47992f86b mm: change invalidatepage prototype to accept length
Currently there is no way to truncate partial page where the end
truncate point is not at the end of the page. This is because it was not
needed and the functionality was enough for file system truncate
operation to work properly. However more file systems now support punch
hole feature and it can benefit from mm supporting truncating page just
up to the certain point.

Specifically, with this functionality truncate_inode_pages_range() can
be changed so it supports truncating partial page at the end of the
range (currently it will BUG_ON() if 'end' is not at the end of the
page).

This commit changes the invalidatepage() address space operation
prototype to accept range to be invalidated and update all the instances
for it.

We also change the block_invalidatepage() in the same way and actually
make a use of the new length argument implementing range invalidation.

Actual file system implementations will follow except the file systems
where the changes are really simple and should not change the behaviour
in any way .Implementation for truncate_page_range() which will be able
to accept page unaligned ranges will follow as well.

Signed-off-by: Lukas Czerner <lczerner@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Hugh Dickins <hughd@google.com>
2013-05-21 23:17:23 -04:00

355 lines
8.3 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 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;
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,
};