60e78d2c99
This patch adds a persistent, read-only caching facility for 9p clients using the FS-Cache caching backend. When the fscache facility is enabled, each inode is associated with a corresponding vcookie which is an index into the FS-Cache indexing tree. The FS-Cache indexing tree is indexed at 3 levels: - session object associated with each mount. - inode/vcookie - actual data (pages) A cache tag is chosen randomly for each session. These tags can be read off /sys/fs/9p/caches and can be passed as a mount-time parameter to re-attach to the specified caching session. Signed-off-by: Abhishek Kulkarni <adkulkar@umail.iu.edu> Signed-off-by: Eric Van Hensbergen <ericvh@gmail.com>
164 lines
3.8 KiB
C
164 lines
3.8 KiB
C
/*
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* linux/fs/9p/vfs_addr.c
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*
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* This file contians vfs address (mmap) ops for 9P2000.
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*
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* Copyright (C) 2005 by Eric Van Hensbergen <ericvh@gmail.com>
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* Copyright (C) 2002 by Ron Minnich <rminnich@lanl.gov>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2
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* as published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to:
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* Free Software Foundation
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* 51 Franklin Street, Fifth Floor
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* Boston, MA 02111-1301 USA
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*
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*/
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#include <linux/module.h>
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#include <linux/errno.h>
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#include <linux/fs.h>
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#include <linux/file.h>
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#include <linux/stat.h>
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#include <linux/string.h>
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#include <linux/inet.h>
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#include <linux/pagemap.h>
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#include <linux/idr.h>
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#include <linux/sched.h>
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#include <net/9p/9p.h>
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#include <net/9p/client.h>
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#include "v9fs.h"
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#include "v9fs_vfs.h"
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#include "cache.h"
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/**
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* v9fs_vfs_readpage - read an entire page in from 9P
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*
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* @filp: file being read
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* @page: structure to page
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*
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*/
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static int v9fs_vfs_readpage(struct file *filp, struct page *page)
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{
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int retval;
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loff_t offset;
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char *buffer;
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struct inode *inode;
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inode = page->mapping->host;
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P9_DPRINTK(P9_DEBUG_VFS, "\n");
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BUG_ON(!PageLocked(page));
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retval = v9fs_readpage_from_fscache(inode, page);
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if (retval == 0)
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return retval;
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buffer = kmap(page);
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offset = page_offset(page);
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retval = v9fs_file_readn(filp, buffer, NULL, PAGE_CACHE_SIZE, offset);
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if (retval < 0) {
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v9fs_uncache_page(inode, page);
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goto done;
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}
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memset(buffer + retval, 0, PAGE_CACHE_SIZE - retval);
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flush_dcache_page(page);
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SetPageUptodate(page);
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v9fs_readpage_to_fscache(inode, page);
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retval = 0;
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done:
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kunmap(page);
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unlock_page(page);
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return retval;
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}
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/**
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* v9fs_vfs_readpages - read a set of pages from 9P
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*
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* @filp: file being read
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* @mapping: the address space
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* @pages: list of pages to read
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* @nr_pages: count of pages to read
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*
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*/
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static int v9fs_vfs_readpages(struct file *filp, struct address_space *mapping,
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struct list_head *pages, unsigned nr_pages)
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{
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int ret = 0;
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struct inode *inode;
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inode = mapping->host;
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P9_DPRINTK(P9_DEBUG_VFS, "inode: %p file: %p\n", inode, filp);
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ret = v9fs_readpages_from_fscache(inode, mapping, pages, &nr_pages);
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if (ret == 0)
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return ret;
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ret = read_cache_pages(mapping, pages, (void *)v9fs_vfs_readpage, filp);
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P9_DPRINTK(P9_DEBUG_VFS, " = %d\n", ret);
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return ret;
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}
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/**
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* v9fs_release_page - release the private state associated with a page
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*
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* Returns 1 if the page can be released, false otherwise.
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*/
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static int v9fs_release_page(struct page *page, gfp_t gfp)
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{
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if (PagePrivate(page))
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return 0;
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return v9fs_fscache_release_page(page, gfp);
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}
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/**
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* v9fs_invalidate_page - Invalidate a page completely or partially
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*
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* @page: structure to page
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* @offset: offset in the page
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*/
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static void v9fs_invalidate_page(struct page *page, unsigned long offset)
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{
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if (offset == 0)
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v9fs_fscache_invalidate_page(page);
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}
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/**
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* v9fs_launder_page - Writeback a dirty page
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* Since the writes go directly to the server, we simply return a 0
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* here to indicate success.
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*
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* Returns 0 on success.
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*/
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static int v9fs_launder_page(struct page *page)
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{
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return 0;
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}
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const struct address_space_operations v9fs_addr_operations = {
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.readpage = v9fs_vfs_readpage,
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.readpages = v9fs_vfs_readpages,
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.releasepage = v9fs_release_page,
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.invalidatepage = v9fs_invalidate_page,
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.launder_page = v9fs_launder_page,
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};
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