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/slab.h> 28 #include <linux/sched.h> 29 #include <linux/idr.h> 30 #include <net/9p/9p.h> 31 #include <net/9p/client.h> 32 33 #include "v9fs.h" 34 #include "v9fs_vfs.h" 35 #include "fid.h" 36 37 /** 38 * v9fs_fid_add - add a fid to a dentry 39 * @dentry: dentry that the fid is being added to 40 * @fid: fid to add 41 * 42 */ 43 44 int v9fs_fid_add(struct dentry *dentry, struct p9_fid *fid) 45 { 46 struct v9fs_dentry *dent; 47 48 P9_DPRINTK(P9_DEBUG_VFS, "fid %d dentry %s\n", 49 fid->fid, dentry->d_name.name); 50 51 dent = dentry->d_fsdata; 52 if (!dent) { 53 dent = kmalloc(sizeof(struct v9fs_dentry), GFP_KERNEL); 54 if (!dent) 55 return -ENOMEM; 56 57 spin_lock_init(&dent->lock); 58 INIT_LIST_HEAD(&dent->fidlist); 59 dentry->d_fsdata = dent; 60 } 61 62 spin_lock(&dent->lock); 63 list_add(&fid->dlist, &dent->fidlist); 64 spin_unlock(&dent->lock); 65 66 return 0; 67 } 68 69 /** 70 * v9fs_fid_find - retrieve a fid that belongs to the specified uid 71 * @dentry: dentry to look for fid in 72 * @uid: return fid that belongs to the specified user 73 * @any: if non-zero, return any fid associated with the dentry 74 * 75 */ 76 77 static struct p9_fid *v9fs_fid_find(struct dentry *dentry, u32 uid, int any) 78 { 79 struct v9fs_dentry *dent; 80 struct p9_fid *fid, *ret; 81 82 P9_DPRINTK(P9_DEBUG_VFS, " dentry: %s (%p) uid %d any %d\n", 83 dentry->d_name.name, dentry, uid, any); 84 dent = (struct v9fs_dentry *) dentry->d_fsdata; 85 ret = NULL; 86 if (dent) { 87 spin_lock(&dent->lock); 88 list_for_each_entry(fid, &dent->fidlist, dlist) { 89 if (any || fid->uid == uid) { 90 ret = fid; 91 break; 92 } 93 } 94 spin_unlock(&dent->lock); 95 } 96 97 return ret; 98 } 99 100 /** 101 * v9fs_fid_lookup - lookup for a fid, try to walk if not found 102 * @dentry: dentry to look for fid in 103 * 104 * Look for a fid in the specified dentry for the current user. 105 * If no fid is found, try to create one walking from a fid from the parent 106 * dentry (if it has one), or the root dentry. If the user haven't accessed 107 * the fs yet, attach now and walk from the root. 108 */ 109 110 struct p9_fid *v9fs_fid_lookup(struct dentry *dentry) 111 { 112 int i, n, l, clone, any, access; 113 u32 uid; 114 struct p9_fid *fid, *old_fid = NULL; 115 struct dentry *d, *ds; 116 struct v9fs_session_info *v9ses; 117 char **wnames, *uname; 118 119 v9ses = v9fs_inode2v9ses(dentry->d_inode); 120 access = v9ses->flags & V9FS_ACCESS_MASK; 121 switch (access) { 122 case V9FS_ACCESS_SINGLE: 123 case V9FS_ACCESS_USER: 124 uid = current_fsuid(); 125 any = 0; 126 break; 127 128 case V9FS_ACCESS_ANY: 129 uid = v9ses->uid; 130 any = 1; 131 break; 132 133 default: 134 uid = ~0; 135 any = 0; 136 break; 137 } 138 139 fid = v9fs_fid_find(dentry, uid, any); 140 if (fid) 141 return fid; 142 143 ds = dentry->d_parent; 144 fid = v9fs_fid_find(ds, uid, any); 145 if (!fid) { /* walk from the root */ 146 n = 0; 147 for (ds = dentry; !IS_ROOT(ds); ds = ds->d_parent) 148 n++; 149 150 fid = v9fs_fid_find(ds, uid, any); 151 if (!fid) { /* the user is not attached to the fs yet */ 152 if (access == V9FS_ACCESS_SINGLE) 153 return ERR_PTR(-EPERM); 154 155 if (v9fs_proto_dotu(v9ses)) 156 uname = NULL; 157 else 158 uname = v9ses->uname; 159 160 fid = p9_client_attach(v9ses->clnt, NULL, uname, uid, 161 v9ses->aname); 162 163 if (IS_ERR(fid)) 164 return fid; 165 166 v9fs_fid_add(ds, fid); 167 } 168 } else /* walk from the parent */ 169 n = 1; 170 171 if (ds == dentry) 172 return fid; 173 174 wnames = kmalloc(sizeof(char *) * n, GFP_KERNEL); 175 if (!wnames) 176 return ERR_PTR(-ENOMEM); 177 178 for (d = dentry, i = (n-1); i >= 0; i--, d = d->d_parent) 179 wnames[i] = (char *) d->d_name.name; 180 181 clone = 1; 182 i = 0; 183 while (i < n) { 184 l = min(n - i, P9_MAXWELEM); 185 fid = p9_client_walk(fid, l, &wnames[i], clone); 186 if (IS_ERR(fid)) { 187 if (old_fid) { 188 /* 189 * If we fail, clunk fid which are mapping 190 * to path component and not the last component 191 * of the path. 192 */ 193 p9_client_clunk(old_fid); 194 } 195 kfree(wnames); 196 return fid; 197 } 198 old_fid = fid; 199 i += l; 200 clone = 0; 201 } 202 203 kfree(wnames); 204 v9fs_fid_add(dentry, fid); 205 return fid; 206 } 207 208 struct p9_fid *v9fs_fid_clone(struct dentry *dentry) 209 { 210 struct p9_fid *fid, *ret; 211 212 fid = v9fs_fid_lookup(dentry); 213 if (IS_ERR(fid)) 214 return fid; 215 216 ret = p9_client_walk(fid, 0, NULL, 1); 217 return ret; 218 } 219