1 /* 2 * V9FS FID Management 3 * 4 * Copyright (C) 2007 by Latchesar Ionkov <lucho@ionkov.net> 5 * Copyright (C) 2005, 2006 by Eric Van Hensbergen <ericvh@gmail.com> 6 * 7 * This program is free software; you can redistribute it and/or modify 8 * it under the terms of the GNU General Public License version 2 9 * as published by the Free Software Foundation. 10 * 11 * This program is distributed in the hope that it will be useful, 12 * but WITHOUT ANY WARRANTY; without even the implied warranty of 13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 14 * GNU General Public License for more details. 15 * 16 * You should have received a copy of the GNU General Public License 17 * along with this program; if not, write to: 18 * Free Software Foundation 19 * 51 Franklin Street, Fifth Floor 20 * Boston, MA 02111-1301 USA 21 * 22 */ 23 24 #include <linux/module.h> 25 #include <linux/errno.h> 26 #include <linux/fs.h> 27 #include <linux/sched.h> 28 #include <linux/idr.h> 29 #include <net/9p/9p.h> 30 #include <net/9p/client.h> 31 32 #include "v9fs.h" 33 #include "v9fs_vfs.h" 34 #include "fid.h" 35 36 /** 37 * v9fs_fid_add - add a fid to a dentry 38 * @dentry: dentry that the fid is being added to 39 * @fid: fid to add 40 * 41 */ 42 43 int v9fs_fid_add(struct dentry *dentry, struct p9_fid *fid) 44 { 45 struct v9fs_dentry *dent; 46 47 P9_DPRINTK(P9_DEBUG_VFS, "fid %d dentry %s\n", 48 fid->fid, dentry->d_name.name); 49 50 dent = dentry->d_fsdata; 51 if (!dent) { 52 dent = kmalloc(sizeof(struct v9fs_dentry), GFP_KERNEL); 53 if (!dent) 54 return -ENOMEM; 55 56 spin_lock_init(&dent->lock); 57 INIT_LIST_HEAD(&dent->fidlist); 58 dentry->d_fsdata = dent; 59 } 60 61 spin_lock(&dent->lock); 62 list_add(&fid->dlist, &dent->fidlist); 63 spin_unlock(&dent->lock); 64 65 return 0; 66 } 67 68 /** 69 * v9fs_fid_find - retrieve a fid that belongs to the specified uid 70 * @dentry: dentry to look for fid in 71 * @uid: return fid that belongs to the specified user 72 * @any: if non-zero, return any fid associated with the dentry 73 * 74 */ 75 76 static struct p9_fid *v9fs_fid_find(struct dentry *dentry, u32 uid, int any) 77 { 78 struct v9fs_dentry *dent; 79 struct p9_fid *fid, *ret; 80 81 P9_DPRINTK(P9_DEBUG_VFS, " dentry: %s (%p) uid %d any %d\n", 82 dentry->d_name.name, dentry, uid, any); 83 dent = (struct v9fs_dentry *) dentry->d_fsdata; 84 ret = NULL; 85 if (dent) { 86 spin_lock(&dent->lock); 87 list_for_each_entry(fid, &dent->fidlist, dlist) { 88 if (any || fid->uid == uid) { 89 ret = fid; 90 break; 91 } 92 } 93 spin_unlock(&dent->lock); 94 } 95 96 return ret; 97 } 98 99 /** 100 * v9fs_fid_lookup - lookup for a fid, try to walk if not found 101 * @dentry: dentry to look for fid in 102 * 103 * Look for a fid in the specified dentry for the current user. 104 * If no fid is found, try to create one walking from a fid from the parent 105 * dentry (if it has one), or the root dentry. If the user haven't accessed 106 * the fs yet, attach now and walk from the root. 107 */ 108 109 struct p9_fid *v9fs_fid_lookup(struct dentry *dentry) 110 { 111 int i, n, l, clone, any, access; 112 u32 uid; 113 struct p9_fid *fid; 114 struct dentry *d, *ds; 115 struct v9fs_session_info *v9ses; 116 char **wnames, *uname; 117 118 v9ses = v9fs_inode2v9ses(dentry->d_inode); 119 access = v9ses->flags & V9FS_ACCESS_MASK; 120 switch (access) { 121 case V9FS_ACCESS_SINGLE: 122 case V9FS_ACCESS_USER: 123 uid = current_fsuid(); 124 any = 0; 125 break; 126 127 case V9FS_ACCESS_ANY: 128 uid = v9ses->uid; 129 any = 1; 130 break; 131 132 default: 133 uid = ~0; 134 any = 0; 135 break; 136 } 137 138 fid = v9fs_fid_find(dentry, uid, any); 139 if (fid) 140 return fid; 141 142 ds = dentry->d_parent; 143 fid = v9fs_fid_find(ds, uid, any); 144 if (!fid) { /* walk from the root */ 145 n = 0; 146 for (ds = dentry; !IS_ROOT(ds); ds = ds->d_parent) 147 n++; 148 149 fid = v9fs_fid_find(ds, uid, any); 150 if (!fid) { /* the user is not attached to the fs yet */ 151 if (access == V9FS_ACCESS_SINGLE) 152 return ERR_PTR(-EPERM); 153 154 if (v9fs_proto_dotu(v9ses)) 155 uname = NULL; 156 else 157 uname = v9ses->uname; 158 159 fid = p9_client_attach(v9ses->clnt, NULL, uname, uid, 160 v9ses->aname); 161 162 if (IS_ERR(fid)) 163 return fid; 164 165 v9fs_fid_add(ds, fid); 166 } 167 } else /* walk from the parent */ 168 n = 1; 169 170 if (ds == dentry) 171 return fid; 172 173 wnames = kmalloc(sizeof(char *) * n, GFP_KERNEL); 174 if (!wnames) 175 return ERR_PTR(-ENOMEM); 176 177 for (d = dentry, i = (n-1); i >= 0; i--, d = d->d_parent) 178 wnames[i] = (char *) d->d_name.name; 179 180 clone = 1; 181 i = 0; 182 while (i < n) { 183 l = min(n - i, P9_MAXWELEM); 184 fid = p9_client_walk(fid, l, &wnames[i], clone); 185 if (IS_ERR(fid)) { 186 kfree(wnames); 187 return fid; 188 } 189 190 i += l; 191 clone = 0; 192 } 193 194 kfree(wnames); 195 v9fs_fid_add(dentry, fid); 196 return fid; 197 } 198 199 struct p9_fid *v9fs_fid_clone(struct dentry *dentry) 200 { 201 struct p9_fid *fid, *ret; 202 203 fid = v9fs_fid_lookup(dentry); 204 if (IS_ERR(fid)) 205 return fid; 206 207 ret = p9_client_walk(fid, 0, NULL, 1); 208 return ret; 209 } 210