1 /* 2 * V9FS FID Management 3 * 4 * Copyright (C) 2005 by Eric Van Hensbergen <ericvh@gmail.com> 5 * 6 * This program is free software; you can redistribute it and/or modify 7 * it under the terms of the GNU General Public License as published by 8 * the Free Software Foundation; either version 2 of the License, or 9 * (at your option) any later version. 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/config.h> 25 #include <linux/module.h> 26 #include <linux/errno.h> 27 #include <linux/fs.h> 28 #include <linux/idr.h> 29 30 #include "debug.h" 31 #include "v9fs.h" 32 #include "9p.h" 33 #include "v9fs_vfs.h" 34 #include "transport.h" 35 #include "mux.h" 36 #include "conv.h" 37 #include "fid.h" 38 39 /** 40 * v9fs_fid_insert - add a fid to a dentry 41 * @fid: fid to add 42 * @dentry: dentry that it is being added to 43 * 44 */ 45 46 static int v9fs_fid_insert(struct v9fs_fid *fid, struct dentry *dentry) 47 { 48 struct list_head *fid_list = (struct list_head *)dentry->d_fsdata; 49 dprintk(DEBUG_9P, "fid %d (%p) dentry %s (%p)\n", fid->fid, fid, 50 dentry->d_iname, dentry); 51 if (dentry->d_fsdata == NULL) { 52 dentry->d_fsdata = 53 kmalloc(sizeof(struct list_head), GFP_KERNEL); 54 if (dentry->d_fsdata == NULL) { 55 dprintk(DEBUG_ERROR, "Out of memory\n"); 56 return -ENOMEM; 57 } 58 fid_list = (struct list_head *)dentry->d_fsdata; 59 INIT_LIST_HEAD(fid_list); /* Initialize list head */ 60 } 61 62 fid->uid = current->uid; 63 fid->pid = current->pid; 64 list_add(&fid->list, fid_list); 65 return 0; 66 } 67 68 /** 69 * v9fs_fid_create - allocate a FID structure 70 * @dentry - dentry to link newly created fid to 71 * 72 */ 73 74 struct v9fs_fid *v9fs_fid_create(struct dentry *dentry, 75 struct v9fs_session_info *v9ses, int fid, int create) 76 { 77 struct v9fs_fid *new; 78 79 dprintk(DEBUG_9P, "fid create dentry %p, fid %d, create %d\n", 80 dentry, fid, create); 81 82 new = kmalloc(sizeof(struct v9fs_fid), GFP_KERNEL); 83 if (new == NULL) { 84 dprintk(DEBUG_ERROR, "Out of Memory\n"); 85 return ERR_PTR(-ENOMEM); 86 } 87 88 new->fid = fid; 89 new->v9ses = v9ses; 90 new->fidopen = 0; 91 new->fidcreate = create; 92 new->fidclunked = 0; 93 new->iounit = 0; 94 new->rdir_pos = 0; 95 new->rdir_fcall = NULL; 96 97 if (v9fs_fid_insert(new, dentry) == 0) 98 return new; 99 else { 100 dprintk(DEBUG_ERROR, "Problems inserting to dentry\n"); 101 kfree(new); 102 return NULL; 103 } 104 } 105 106 /** 107 * v9fs_fid_destroy - deallocate a FID structure 108 * @fid: fid to destroy 109 * 110 */ 111 112 void v9fs_fid_destroy(struct v9fs_fid *fid) 113 { 114 list_del(&fid->list); 115 kfree(fid); 116 } 117 118 /** 119 * v9fs_fid_walk_up - walks from the process current directory 120 * up to the specified dentry. 121 */ 122 static struct v9fs_fid *v9fs_fid_walk_up(struct dentry *dentry) 123 { 124 int fidnum, cfidnum, err; 125 struct v9fs_fid *cfid; 126 struct dentry *cde; 127 struct v9fs_session_info *v9ses; 128 129 v9ses = v9fs_inode2v9ses(current->fs->pwd->d_inode); 130 cfid = v9fs_fid_lookup(current->fs->pwd); 131 if (cfid == NULL) { 132 dprintk(DEBUG_ERROR, "process cwd doesn't have a fid\n"); 133 return ERR_PTR(-ENOENT); 134 } 135 136 cfidnum = cfid->fid; 137 cde = current->fs->pwd; 138 /* TODO: take advantage of multiwalk */ 139 140 fidnum = v9fs_get_idpool(&v9ses->fidpool); 141 if (fidnum < 0) { 142 dprintk(DEBUG_ERROR, "could not get a new fid num\n"); 143 err = -ENOENT; 144 goto clunk_fid; 145 } 146 147 while (cde != dentry) { 148 if (cde == cde->d_parent) { 149 dprintk(DEBUG_ERROR, "can't find dentry\n"); 150 err = -ENOENT; 151 goto clunk_fid; 152 } 153 154 err = v9fs_t_walk(v9ses, cfidnum, fidnum, "..", NULL); 155 if (err < 0) { 156 dprintk(DEBUG_ERROR, "problem walking to parent\n"); 157 goto clunk_fid; 158 } 159 160 cfidnum = fidnum; 161 cde = cde->d_parent; 162 } 163 164 return v9fs_fid_create(dentry, v9ses, fidnum, 0); 165 166 clunk_fid: 167 v9fs_t_clunk(v9ses, fidnum, NULL); 168 return ERR_PTR(err); 169 } 170 171 /** 172 * v9fs_fid_lookup - retrieve the right fid from a particular dentry 173 * @dentry: dentry to look for fid in 174 * @type: intent of lookup (operation or traversal) 175 * 176 * search list of fids associated with a dentry for a fid with a matching 177 * thread id or uid. If that fails, look up the dentry's parents to see if you 178 * can find a matching fid. 179 * 180 */ 181 182 struct v9fs_fid *v9fs_fid_lookup(struct dentry *dentry) 183 { 184 struct list_head *fid_list = (struct list_head *)dentry->d_fsdata; 185 struct v9fs_fid *current_fid = NULL; 186 struct v9fs_fid *temp = NULL; 187 struct v9fs_fid *return_fid = NULL; 188 189 dprintk(DEBUG_9P, " dentry: %s (%p)\n", dentry->d_iname, dentry); 190 191 if (fid_list) { 192 list_for_each_entry_safe(current_fid, temp, fid_list, list) { 193 if (!current_fid->fidcreate) { 194 return_fid = current_fid; 195 break; 196 } 197 } 198 199 if (!return_fid) 200 return_fid = current_fid; 201 } 202 203 /* we are at the root but didn't match */ 204 if ((!return_fid) && (dentry->d_parent == dentry)) { 205 /* TODO: clone attach with new uid */ 206 return_fid = current_fid; 207 } 208 209 if (!return_fid) { 210 struct dentry *par = current->fs->pwd->d_parent; 211 int count = 1; 212 while (par != NULL) { 213 if (par == dentry) 214 break; 215 count++; 216 if (par == par->d_parent) { 217 dprintk(DEBUG_ERROR, 218 "got to root without finding dentry\n"); 219 break; 220 } 221 par = par->d_parent; 222 } 223 224 /* XXX - there may be some duplication we can get rid of */ 225 if (par == dentry) { 226 return_fid = v9fs_fid_walk_up(dentry); 227 if (IS_ERR(return_fid)) 228 return_fid = NULL; 229 } 230 } 231 232 return return_fid; 233 } 234 235 struct v9fs_fid *v9fs_fid_get_created(struct dentry *dentry) 236 { 237 struct list_head *fid_list; 238 struct v9fs_fid *fid, *ftmp, *ret; 239 240 dprintk(DEBUG_9P, " dentry: %s (%p)\n", dentry->d_iname, dentry); 241 fid_list = (struct list_head *)dentry->d_fsdata; 242 ret = NULL; 243 if (fid_list) { 244 list_for_each_entry_safe(fid, ftmp, fid_list, list) { 245 if (fid->fidcreate && fid->pid == current->pid) { 246 list_del(&fid->list); 247 ret = fid; 248 break; 249 } 250 } 251 } 252 253 dprintk(DEBUG_9P, "return %p\n", ret); 254 return ret; 255 } 256