linux/fs/9p/fid.c
Eric Van Hensbergen 46f6dac259 [PATCH] v9fs: simplify fid mapping
v9fs has been plagued by an over-complicated approach trying to map Linux
dentry semantics to Plan 9 fid semantics.  Our previous approach called for
aggressive flushing of the dcache resulting in several problems (including
wierd cwd behavior when running /bin/pwd).

This patch dramatically simplifies our handling of this fid management.  Fids
will not be clunked as promptly, but the new approach is more functionally
correct.  We now clunk un-open fids only when their dentry ref_count reaches 0
(and d_delete is called).

Another simplification is we no longer seek to match fids to the process-id or
uid of the action initiator.  The uid-matching will need to be revisited when
we fix the security model.

Signed-off-by: Eric Van Hensbergen <ericvh@gmail.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-02 08:33:07 -08:00

131 lines
3.2 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 as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* 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/config.h>
#include <linux/module.h>
#include <linux/errno.h>
#include <linux/fs.h>
#include <linux/idr.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_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 - retrieve the right fid from a particular dentry
* @dentry: dentry to look for fid in
* @type: intent of lookup (operation or traversal)
*
* find a fid in the dentry
*
* 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 return_fid;
}