/* * V9FS FID Management * * Copyright (C) 2007 by Latchesar Ionkov <lucho@ionkov.net> * 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/slab.h> #include <linux/sched.h> #include <linux/idr.h> #include <net/9p/9p.h> #include <net/9p/client.h> #include "v9fs.h" #include "v9fs_vfs.h" #include "fid.h" /** * v9fs_fid_add - add a fid to a dentry * @dentry: dentry that the fid is being added to * @fid: fid to add * */ int v9fs_fid_add(struct dentry *dentry, struct p9_fid *fid) { struct v9fs_dentry *dent; P9_DPRINTK(P9_DEBUG_VFS, "fid %d dentry %s\n", fid->fid, dentry->d_name.name); dent = dentry->d_fsdata; if (!dent) { dent = kmalloc(sizeof(struct v9fs_dentry), GFP_KERNEL); if (!dent) return -ENOMEM; spin_lock_init(&dent->lock); INIT_LIST_HEAD(&dent->fidlist); dentry->d_fsdata = dent; } spin_lock(&dent->lock); list_add(&fid->dlist, &dent->fidlist); spin_unlock(&dent->lock); return 0; } /** * v9fs_fid_find - retrieve a fid that belongs to the specified uid * @dentry: dentry to look for fid in * @uid: return fid that belongs to the specified user * @any: if non-zero, return any fid associated with the dentry * */ static struct p9_fid *v9fs_fid_find(struct dentry *dentry, u32 uid, int any) { struct v9fs_dentry *dent; struct p9_fid *fid, *ret; P9_DPRINTK(P9_DEBUG_VFS, " dentry: %s (%p) uid %d any %d\n", dentry->d_name.name, dentry, uid, any); dent = (struct v9fs_dentry *) dentry->d_fsdata; ret = NULL; if (dent) { spin_lock(&dent->lock); list_for_each_entry(fid, &dent->fidlist, dlist) { if (any || fid->uid == uid) { ret = fid; break; } } spin_unlock(&dent->lock); } return ret; } /** * v9fs_fid_lookup - lookup for a fid, try to walk if not found * @dentry: dentry to look for fid in * * Look for a fid in the specified dentry for the current user. * If no fid is found, try to create one walking from a fid from the parent * dentry (if it has one), or the root dentry. If the user haven't accessed * the fs yet, attach now and walk from the root. */ struct p9_fid *v9fs_fid_lookup(struct dentry *dentry) { int i, n, l, clone, any, access; u32 uid; struct p9_fid *fid, *old_fid = NULL; struct dentry *d, *ds; struct v9fs_session_info *v9ses; char **wnames, *uname; v9ses = v9fs_inode2v9ses(dentry->d_inode); access = v9ses->flags & V9FS_ACCESS_MASK; switch (access) { case V9FS_ACCESS_SINGLE: case V9FS_ACCESS_USER: uid = current_fsuid(); any = 0; break; case V9FS_ACCESS_ANY: uid = v9ses->uid; any = 1; break; default: uid = ~0; any = 0; break; } fid = v9fs_fid_find(dentry, uid, any); if (fid) return fid; ds = dentry->d_parent; fid = v9fs_fid_find(ds, uid, any); if (!fid) { /* walk from the root */ n = 0; for (ds = dentry; !IS_ROOT(ds); ds = ds->d_parent) n++; fid = v9fs_fid_find(ds, uid, any); if (!fid) { /* the user is not attached to the fs yet */ if (access == V9FS_ACCESS_SINGLE) return ERR_PTR(-EPERM); if (v9fs_proto_dotu(v9ses)) uname = NULL; else uname = v9ses->uname; fid = p9_client_attach(v9ses->clnt, NULL, uname, uid, v9ses->aname); if (IS_ERR(fid)) return fid; v9fs_fid_add(ds, fid); } } else /* walk from the parent */ n = 1; if (ds == dentry) return fid; wnames = kmalloc(sizeof(char *) * n, GFP_KERNEL); if (!wnames) return ERR_PTR(-ENOMEM); for (d = dentry, i = (n-1); i >= 0; i--, d = d->d_parent) wnames[i] = (char *) d->d_name.name; clone = 1; i = 0; while (i < n) { l = min(n - i, P9_MAXWELEM); fid = p9_client_walk(fid, l, &wnames[i], clone); if (IS_ERR(fid)) { if (old_fid) { /* * If we fail, clunk fid which are mapping * to path component and not the last component * of the path. */ p9_client_clunk(old_fid); } kfree(wnames); return fid; } old_fid = fid; i += l; clone = 0; } kfree(wnames); v9fs_fid_add(dentry, fid); return fid; } struct p9_fid *v9fs_fid_clone(struct dentry *dentry) { struct p9_fid *fid, *ret; fid = v9fs_fid_lookup(dentry); if (IS_ERR(fid)) return fid; ret = p9_client_walk(fid, 0, NULL, 1); return ret; }