Eric Van Hensbergen | 3ed8491 | 2005-09-09 13:04:24 -0700 | [diff] [blame] | 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 | { |
| 76 | struct v9fs_fid *new; |
| 77 | |
| 78 | new = kmalloc(sizeof(struct v9fs_fid), GFP_KERNEL); |
| 79 | if (new == NULL) { |
| 80 | dprintk(DEBUG_ERROR, "Out of Memory\n"); |
| 81 | return ERR_PTR(-ENOMEM); |
| 82 | } |
| 83 | |
| 84 | new->fid = -1; |
| 85 | new->fidopen = 0; |
| 86 | new->fidcreate = 0; |
| 87 | new->fidclunked = 0; |
| 88 | new->iounit = 0; |
| 89 | |
| 90 | if (v9fs_fid_insert(new, dentry) == 0) |
| 91 | return new; |
| 92 | else { |
| 93 | dprintk(DEBUG_ERROR, "Problems inserting to dentry\n"); |
| 94 | kfree(new); |
| 95 | return NULL; |
| 96 | } |
| 97 | } |
| 98 | |
| 99 | /** |
| 100 | * v9fs_fid_destroy - deallocate a FID structure |
| 101 | * @fid: fid to destroy |
| 102 | * |
| 103 | */ |
| 104 | |
| 105 | void v9fs_fid_destroy(struct v9fs_fid *fid) |
| 106 | { |
| 107 | list_del(&fid->list); |
| 108 | kfree(fid); |
| 109 | } |
| 110 | |
| 111 | /** |
| 112 | * v9fs_fid_lookup - retrieve the right fid from a particular dentry |
| 113 | * @dentry: dentry to look for fid in |
| 114 | * @type: intent of lookup (operation or traversal) |
| 115 | * |
| 116 | * search list of fids associated with a dentry for a fid with a matching |
| 117 | * thread id or uid. If that fails, look up the dentry's parents to see if you |
| 118 | * can find a matching fid. |
| 119 | * |
| 120 | */ |
| 121 | |
| 122 | struct v9fs_fid *v9fs_fid_lookup(struct dentry *dentry, int type) |
| 123 | { |
| 124 | struct list_head *fid_list = (struct list_head *)dentry->d_fsdata; |
| 125 | struct v9fs_fid *current_fid = NULL; |
| 126 | struct v9fs_fid *temp = NULL; |
| 127 | struct v9fs_fid *return_fid = NULL; |
| 128 | int found_parent = 0; |
| 129 | int found_user = 0; |
| 130 | |
| 131 | dprintk(DEBUG_9P, " dentry: %s (%p) type %d\n", dentry->d_iname, dentry, |
| 132 | type); |
| 133 | |
| 134 | if (fid_list && !list_empty(fid_list)) { |
| 135 | list_for_each_entry_safe(current_fid, temp, fid_list, list) { |
| 136 | if (current_fid->uid == current->uid) { |
| 137 | if (return_fid == NULL) { |
| 138 | if ((type == FID_OP) |
| 139 | || (!current_fid->fidopen)) { |
| 140 | return_fid = current_fid; |
| 141 | found_user = 1; |
| 142 | } |
| 143 | } |
| 144 | } |
| 145 | if (current_fid->pid == current->real_parent->pid) { |
| 146 | if ((return_fid == NULL) || (found_parent) |
| 147 | || (found_user)) { |
| 148 | if ((type == FID_OP) |
| 149 | || (!current_fid->fidopen)) { |
| 150 | return_fid = current_fid; |
| 151 | found_parent = 1; |
| 152 | found_user = 0; |
| 153 | } |
| 154 | } |
| 155 | } |
| 156 | if (current_fid->pid == current->pid) { |
| 157 | if ((type == FID_OP) || |
| 158 | (!current_fid->fidopen)) { |
| 159 | return_fid = current_fid; |
| 160 | found_parent = 0; |
| 161 | found_user = 0; |
| 162 | } |
| 163 | } |
| 164 | } |
| 165 | } |
| 166 | |
| 167 | /* we are at the root but didn't match */ |
| 168 | if ((!return_fid) && (dentry->d_parent == dentry)) { |
| 169 | /* TODO: clone attach with new uid */ |
| 170 | return_fid = current_fid; |
| 171 | } |
| 172 | |
| 173 | if (!return_fid) { |
| 174 | struct dentry *par = current->fs->pwd->d_parent; |
| 175 | int count = 1; |
| 176 | while (par != NULL) { |
| 177 | if (par == dentry) |
| 178 | break; |
| 179 | count++; |
| 180 | if (par == par->d_parent) { |
| 181 | dprintk(DEBUG_ERROR, |
| 182 | "got to root without finding dentry\n"); |
| 183 | break; |
| 184 | } |
| 185 | par = par->d_parent; |
| 186 | } |
| 187 | |
| 188 | /* XXX - there may be some duplication we can get rid of */ |
| 189 | if (par == dentry) { |
| 190 | /* we need to fid_lookup the starting point */ |
| 191 | int fidnum = -1; |
| 192 | int oldfid = -1; |
| 193 | int result = -1; |
| 194 | struct v9fs_session_info *v9ses = |
| 195 | v9fs_inode2v9ses(current->fs->pwd->d_inode); |
| 196 | |
| 197 | current_fid = |
| 198 | v9fs_fid_lookup(current->fs->pwd, FID_WALK); |
| 199 | if (current_fid == NULL) { |
| 200 | dprintk(DEBUG_ERROR, |
| 201 | "process cwd doesn't have a fid\n"); |
| 202 | return return_fid; |
| 203 | } |
| 204 | oldfid = current_fid->fid; |
| 205 | par = current->fs->pwd; |
| 206 | /* TODO: take advantage of multiwalk */ |
| 207 | |
| 208 | fidnum = v9fs_get_idpool(&v9ses->fidpool); |
| 209 | if (fidnum < 0) { |
| 210 | dprintk(DEBUG_ERROR, |
| 211 | "could not get a new fid num\n"); |
| 212 | return return_fid; |
| 213 | } |
| 214 | |
| 215 | while (par != dentry) { |
| 216 | result = |
| 217 | v9fs_t_walk(v9ses, oldfid, fidnum, "..", |
| 218 | NULL); |
| 219 | if (result < 0) { |
| 220 | dprintk(DEBUG_ERROR, |
| 221 | "problem walking to parent\n"); |
| 222 | |
| 223 | break; |
| 224 | } |
| 225 | oldfid = fidnum; |
| 226 | if (par == par->d_parent) { |
| 227 | dprintk(DEBUG_ERROR, |
| 228 | "can't find dentry\n"); |
| 229 | break; |
| 230 | } |
| 231 | par = par->d_parent; |
| 232 | } |
| 233 | if (par == dentry) { |
| 234 | return_fid = v9fs_fid_create(dentry); |
| 235 | return_fid->fid = fidnum; |
| 236 | } |
| 237 | } |
| 238 | } |
| 239 | |
| 240 | return return_fid; |
| 241 | } |