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https://github.com/torvalds/linux
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46f6dac259
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>
131 lines
3.2 KiB
C
131 lines
3.2 KiB
C
/*
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* V9FS FID Management
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*
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* Copyright (C) 2005, 2006 by Eric Van Hensbergen <ericvh@gmail.com>
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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 as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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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/config.h>
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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/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_fid_insert - add a fid to a dentry
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* @fid: fid to add
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* @dentry: dentry that it is being added to
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*
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*/
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int v9fs_fid_insert(struct v9fs_fid *fid, struct dentry *dentry)
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{
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struct list_head *fid_list = (struct list_head *)dentry->d_fsdata;
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dprintk(DEBUG_9P, "fid %d (%p) dentry %s (%p)\n", fid->fid, fid,
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dentry->d_iname, dentry);
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if (dentry->d_fsdata == NULL) {
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dentry->d_fsdata =
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kmalloc(sizeof(struct list_head), GFP_KERNEL);
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if (dentry->d_fsdata == NULL) {
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dprintk(DEBUG_ERROR, "Out of memory\n");
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return -ENOMEM;
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}
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fid_list = (struct list_head *)dentry->d_fsdata;
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INIT_LIST_HEAD(fid_list); /* Initialize list head */
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}
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fid->uid = current->uid;
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list_add(&fid->list, fid_list);
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return 0;
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}
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/**
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* v9fs_fid_create - allocate a FID structure
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* @dentry - dentry to link newly created fid to
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*
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*/
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struct v9fs_fid *v9fs_fid_create(struct v9fs_session_info *v9ses, int fid)
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{
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struct v9fs_fid *new;
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dprintk(DEBUG_9P, "fid create fid %d\n", fid);
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new = kmalloc(sizeof(struct v9fs_fid), GFP_KERNEL);
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if (new == NULL) {
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dprintk(DEBUG_ERROR, "Out of Memory\n");
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return ERR_PTR(-ENOMEM);
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}
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new->fid = fid;
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new->v9ses = v9ses;
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new->fidopen = 0;
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new->fidclunked = 0;
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new->iounit = 0;
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new->rdir_pos = 0;
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new->rdir_fcall = NULL;
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INIT_LIST_HEAD(&new->list);
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return new;
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}
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/**
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* v9fs_fid_destroy - deallocate a FID structure
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* @fid: fid to destroy
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*
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*/
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void v9fs_fid_destroy(struct v9fs_fid *fid)
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{
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list_del(&fid->list);
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kfree(fid);
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}
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/**
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* v9fs_fid_lookup - retrieve the right fid from a particular dentry
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* @dentry: dentry to look for fid in
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* @type: intent of lookup (operation or traversal)
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*
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* find a fid in the dentry
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*
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* TODO: only match fids that have the same uid as current user
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*
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*/
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struct v9fs_fid *v9fs_fid_lookup(struct dentry *dentry)
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{
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struct list_head *fid_list = (struct list_head *)dentry->d_fsdata;
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struct v9fs_fid *return_fid = NULL;
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dprintk(DEBUG_9P, " dentry: %s (%p)\n", dentry->d_iname, dentry);
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if (fid_list)
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return_fid = list_entry(fid_list->next, struct v9fs_fid, list);
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if (!return_fid) {
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dprintk(DEBUG_ERROR, "Couldn't find a fid in dentry\n");
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}
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return return_fid;
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}
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