e03abc0c96
While cacheing is generally frowned upon in the 9p world, it has its place -- particularly in situations where the remote file system is exclusive and/or read-only. The vacfs views of venti content addressable store are a real-world instance of such a situation. To facilitate higher performance for these workloads (and eventually use the fscache patches), we have enabled a "loose" cache mode which does not attempt to maintain any form of consistency on the page-cache or dcache. This results in over two orders of magnitude performance improvement for cacheable block reads in the Bonnie benchmark. The more aggressive use of the dcache also seems to improve metadata operational performance. Signed-off-by: Eric Van Hensbergen <ericvh@gmail.com>
110 lines
2.5 KiB
C
110 lines
2.5 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/smp_lock.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 "debug.h"
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#include "v9fs.h"
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#include "9p.h"
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#include "v9fs_vfs.h"
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#include "fid.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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* @file: 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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char *buffer = NULL;
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int retval = -EIO;
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loff_t offset = page_offset(page);
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int count = PAGE_CACHE_SIZE;
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struct inode *inode = filp->f_path.dentry->d_inode;
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struct v9fs_session_info *v9ses = v9fs_inode2v9ses(inode);
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int rsize = v9ses->maxdata - V9FS_IOHDRSZ;
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struct v9fs_fid *v9f = filp->private_data;
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struct v9fs_fcall *fcall = NULL;
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int fid = v9f->fid;
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int total = 0;
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int result = 0;
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dprintk(DEBUG_VFS, "\n");
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buffer = kmap(page);
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do {
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if (count < rsize)
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rsize = count;
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result = v9fs_t_read(v9ses, fid, offset, rsize, &fcall);
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if (result < 0) {
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printk(KERN_ERR "v9fs_t_read returned %d\n",
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result);
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kfree(fcall);
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goto UnmapAndUnlock;
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} else
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offset += result;
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memcpy(buffer, fcall->params.rread.data, result);
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count -= result;
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buffer += result;
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total += result;
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kfree(fcall);
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if (result < rsize)
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break;
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} while (count);
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memset(buffer, 0, count);
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flush_dcache_page(page);
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SetPageUptodate(page);
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retval = 0;
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UnmapAndUnlock:
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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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const struct address_space_operations v9fs_addr_operations = {
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.readpage = v9fs_vfs_readpage,
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};
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