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