210 lines
4.6 KiB
C
210 lines
4.6 KiB
C
/*
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* V9FS FID Management
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*
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* Copyright (C) 2007 by Latchesar Ionkov <lucho@ionkov.net>
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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 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/sched.h>
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#include <linux/idr.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 "fid.h"
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/**
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* v9fs_fid_add - add a fid to a dentry
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* @dentry: dentry that the fid is being added to
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* @fid: fid to add
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*
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*/
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int v9fs_fid_add(struct dentry *dentry, struct p9_fid *fid)
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{
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struct v9fs_dentry *dent;
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P9_DPRINTK(P9_DEBUG_VFS, "fid %d dentry %s\n",
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fid->fid, dentry->d_iname);
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dent = dentry->d_fsdata;
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if (!dent) {
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dent = kmalloc(sizeof(struct v9fs_dentry), GFP_KERNEL);
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if (!dent)
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return -ENOMEM;
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spin_lock_init(&dent->lock);
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INIT_LIST_HEAD(&dent->fidlist);
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dentry->d_fsdata = dent;
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}
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spin_lock(&dent->lock);
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list_add(&fid->dlist, &dent->fidlist);
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spin_unlock(&dent->lock);
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return 0;
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}
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/**
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* v9fs_fid_find - retrieve a fid that belongs to the specified uid
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* @dentry: dentry to look for fid in
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* @uid: return fid that belongs to the specified user
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* @any: if non-zero, return any fid associated with the dentry
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*
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*/
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static struct p9_fid *v9fs_fid_find(struct dentry *dentry, u32 uid, int any)
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{
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struct v9fs_dentry *dent;
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struct p9_fid *fid, *ret;
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P9_DPRINTK(P9_DEBUG_VFS, " dentry: %s (%p) uid %d any %d\n",
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dentry->d_iname, dentry, uid, any);
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dent = (struct v9fs_dentry *) dentry->d_fsdata;
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ret = NULL;
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if (dent) {
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spin_lock(&dent->lock);
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list_for_each_entry(fid, &dent->fidlist, dlist) {
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if (any || fid->uid == uid) {
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ret = fid;
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break;
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}
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}
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spin_unlock(&dent->lock);
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}
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return ret;
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}
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/**
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* v9fs_fid_lookup - lookup for a fid, try to walk if not found
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* @dentry: dentry to look for fid in
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*
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* Look for a fid in the specified dentry for the current user.
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* If no fid is found, try to create one walking from a fid from the parent
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* dentry (if it has one), or the root dentry. If the user haven't accessed
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* the fs yet, attach now and walk from the root.
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*/
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struct p9_fid *v9fs_fid_lookup(struct dentry *dentry)
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{
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int i, n, l, clone, any, access;
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u32 uid;
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struct p9_fid *fid;
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struct dentry *d, *ds;
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struct v9fs_session_info *v9ses;
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char **wnames, *uname;
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v9ses = v9fs_inode2v9ses(dentry->d_inode);
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access = v9ses->flags & V9FS_ACCESS_MASK;
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switch (access) {
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case V9FS_ACCESS_SINGLE:
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case V9FS_ACCESS_USER:
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uid = current_fsuid();
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any = 0;
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break;
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case V9FS_ACCESS_ANY:
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uid = v9ses->uid;
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any = 1;
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break;
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default:
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uid = ~0;
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any = 0;
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break;
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}
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fid = v9fs_fid_find(dentry, uid, any);
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if (fid)
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return fid;
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ds = dentry->d_parent;
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fid = v9fs_fid_find(ds, uid, any);
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if (!fid) { /* walk from the root */
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n = 0;
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for (ds = dentry; !IS_ROOT(ds); ds = ds->d_parent)
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n++;
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fid = v9fs_fid_find(ds, uid, any);
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if (!fid) { /* the user is not attached to the fs yet */
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if (access == V9FS_ACCESS_SINGLE)
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return ERR_PTR(-EPERM);
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if (v9fs_extended(v9ses))
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uname = NULL;
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else
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uname = v9ses->uname;
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fid = p9_client_attach(v9ses->clnt, NULL, uname, uid,
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v9ses->aname);
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if (IS_ERR(fid))
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return fid;
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v9fs_fid_add(ds, fid);
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}
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} else /* walk from the parent */
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n = 1;
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if (ds == dentry)
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return fid;
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wnames = kmalloc(sizeof(char *) * n, GFP_KERNEL);
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if (!wnames)
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return ERR_PTR(-ENOMEM);
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for (d = dentry, i = (n-1); i >= 0; i--, d = d->d_parent)
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wnames[i] = (char *) d->d_name.name;
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clone = 1;
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i = 0;
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while (i < n) {
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l = min(n - i, P9_MAXWELEM);
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fid = p9_client_walk(fid, l, &wnames[i], clone);
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if (IS_ERR(fid)) {
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kfree(wnames);
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return fid;
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}
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i += l;
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clone = 0;
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}
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kfree(wnames);
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v9fs_fid_add(dentry, fid);
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return fid;
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}
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struct p9_fid *v9fs_fid_clone(struct dentry *dentry)
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{
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struct p9_fid *fid, *ret;
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fid = v9fs_fid_lookup(dentry);
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if (IS_ERR(fid))
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return fid;
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ret = p9_client_walk(fid, 0, NULL, 1);
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return ret;
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}
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