linux/fs/9p/fid.c
Eric Van Hensbergen e03abc0c96 9p: implement optional loose read cache
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>
2007-02-18 10:16:10 -06:00

195 lines
4.6 KiB
C

/*
* V9FS FID Management
*
* Copyright (C) 2005, 2006 by Eric Van Hensbergen <ericvh@gmail.com>
*
* 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/sched.h>
#include <linux/idr.h>
#include <asm/semaphore.h>
#include "debug.h"
#include "v9fs.h"
#include "9p.h"
#include "v9fs_vfs.h"
#include "fid.h"
/**
* v9fs_fid_insert - add a fid to a dentry
* @fid: fid to add
* @dentry: dentry that it is being added to
*
*/
int v9fs_fid_insert(struct v9fs_fid *fid, struct dentry *dentry)
{
struct list_head *fid_list = (struct list_head *)dentry->d_fsdata;
dprintk(DEBUG_9P, "fid %d (%p) dentry %s (%p)\n", fid->fid, fid,
dentry->d_iname, dentry);
if (dentry->d_fsdata == NULL) {
dentry->d_fsdata =
kmalloc(sizeof(struct list_head), GFP_KERNEL);
if (dentry->d_fsdata == NULL) {
dprintk(DEBUG_ERROR, "Out of memory\n");
return -ENOMEM;
}
fid_list = (struct list_head *)dentry->d_fsdata;
INIT_LIST_HEAD(fid_list); /* Initialize list head */
}
fid->uid = current->uid;
list_add(&fid->list, fid_list);
return 0;
}
/**
* v9fs_fid_create - allocate a FID structure
* @dentry - dentry to link newly created fid to
*
*/
struct v9fs_fid *v9fs_fid_create(struct v9fs_session_info *v9ses, int fid)
{
struct v9fs_fid *new;
dprintk(DEBUG_9P, "fid create fid %d\n", fid);
new = kmalloc(sizeof(struct v9fs_fid), GFP_KERNEL);
if (new == NULL) {
dprintk(DEBUG_ERROR, "Out of Memory\n");
return ERR_PTR(-ENOMEM);
}
new->fid = fid;
new->v9ses = v9ses;
new->fidopen = 0;
new->fidclunked = 0;
new->iounit = 0;
new->rdir_pos = 0;
new->rdir_fcall = NULL;
init_MUTEX(&new->lock);
INIT_LIST_HEAD(&new->list);
return new;
}
/**
* v9fs_fid_destroy - deallocate a FID structure
* @fid: fid to destroy
*
*/
void v9fs_fid_destroy(struct v9fs_fid *fid)
{
list_del(&fid->list);
kfree(fid);
}
/**
* v9fs_fid_lookup - return a locked fid from a dentry
* @dentry: dentry to look for fid in
*
* find a fid in the dentry, obtain its semaphore and return a reference to it.
* code calling lookup is responsible for releasing lock
*
* TODO: only match fids that have the same uid as current user
*
*/
struct v9fs_fid *v9fs_fid_lookup(struct dentry *dentry)
{
struct list_head *fid_list = (struct list_head *)dentry->d_fsdata;
struct v9fs_fid *return_fid = NULL;
dprintk(DEBUG_9P, " dentry: %s (%p)\n", dentry->d_iname, dentry);
if (fid_list)
return_fid = list_entry(fid_list->next, struct v9fs_fid, list);
if (!return_fid) {
dprintk(DEBUG_ERROR, "Couldn't find a fid in dentry\n");
return_fid = ERR_PTR(-EBADF);
}
if(down_interruptible(&return_fid->lock))
return ERR_PTR(-EINTR);
return return_fid;
}
/**
* v9fs_fid_clone - lookup the fid for a dentry, clone a private copy and
* release it
* @dentry: dentry to look for fid in
*
* find a fid in the dentry and then clone to a new private fid
*
* TODO: only match fids that have the same uid as current user
*
*/
struct v9fs_fid *v9fs_fid_clone(struct dentry *dentry)
{
struct v9fs_session_info *v9ses = v9fs_inode2v9ses(dentry->d_inode);
struct v9fs_fid *base_fid, *new_fid = ERR_PTR(-EBADF);
struct v9fs_fcall *fcall = NULL;
int fid, err;
base_fid = v9fs_fid_lookup(dentry);
if(IS_ERR(base_fid))
return base_fid;
if(base_fid) { /* clone fid */
fid = v9fs_get_idpool(&v9ses->fidpool);
if (fid < 0) {
eprintk(KERN_WARNING, "newfid fails!\n");
new_fid = ERR_PTR(-ENOSPC);
goto Release_Fid;
}
err = v9fs_t_walk(v9ses, base_fid->fid, fid, NULL, &fcall);
if (err < 0) {
dprintk(DEBUG_ERROR, "clone walk didn't work\n");
v9fs_put_idpool(fid, &v9ses->fidpool);
new_fid = ERR_PTR(err);
goto Free_Fcall;
}
new_fid = v9fs_fid_create(v9ses, fid);
if (new_fid == NULL) {
dprintk(DEBUG_ERROR, "out of memory\n");
new_fid = ERR_PTR(-ENOMEM);
}
Free_Fcall:
kfree(fcall);
}
Release_Fid:
up(&base_fid->lock);
return new_fid;
}
void v9fs_fid_clunk(struct v9fs_session_info *v9ses, struct v9fs_fid *fid)
{
v9fs_t_clunk(v9ses, fid->fid);
v9fs_fid_destroy(fid);
}