fs/9p/vfs_dir.c

   1 /*
   2  * linux/fs/9p/vfs_dir.c
   3  *
   4  * This file contains vfs directory ops for the 9P2000 protocol.
   5  *
   6  *  Copyright (C) 2004 by Eric Van Hensbergen <ericvh@gmail.com>
   7  *  Copyright (C) 2002 by Ron Minnich <rminnich@lanl.gov>
   8  *
   9  *  This program is free software; you can redistribute it and/or modify
  10  *  it under the terms of the GNU General Public License version 2
  11  *  as published by the Free Software Foundation.
  12  *
  13  *  This program is distributed in the hope that it will be useful,
  14  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16  *  GNU General Public License for more details.
  17  *
  18  *  You should have received a copy of the GNU General Public License
  19  *  along with this program; if not, write to:
  20  *  Free Software Foundation
  21  *  51 Franklin Street, Fifth Floor
  22  *  Boston, MA  02111-1301  USA
  23  *
  24  */
  25
  26 #include <linux/module.h>
  27 #include <linux/errno.h>
  28 #include <linux/fs.h>
  29 #include <linux/file.h>
  30 #include <linux/stat.h>
  31 #include <linux/string.h>
  32 #include <linux/sched.h>
  33 #include <linux/inet.h>
  34 #include <linux/idr.h>
  35 #include <linux/slab.h>
  36 #include <net/9p/9p.h>
  37 #include <net/9p/client.h>
  38
  39 #include "v9fs.h"
  40 #include "v9fs_vfs.h"
  41 #include "fid.h"
  42
  43 /**
  44  * struct p9_rdir - readdir accounting
  45  * @mutex: mutex protecting readdir
  46  * @head: start offset of current dirread buffer
  47  * @tail: end offset of current dirread buffer
  48  * @buf: dirread buffer
  49  *
  50  * private structure for keeping track of readdir
  51  * allocated on demand
  52  */
  53
  54 struct p9_rdir {
  55         struct mutex mutex;
  56         int head;
  57         int tail;
  58         uint8_t *buf;
  59 };
  60
  61 /**
  62  * dt_type - return file type
  63  * @mistat: mistat structure
  64  *
  65  */
  66
  67 static inline int dt_type(struct p9_wstat *mistat)
  68 {
  69         unsigned long perm = mistat->mode;
  70         int rettype = DT_REG;
  71
  72         if (perm & P9_DMDIR)
  73                 rettype = DT_DIR;
  74         if (perm & P9_DMSYMLINK)
  75                 rettype = DT_LNK;
  76
  77         return rettype;
  78 }
  79
  80 static void p9stat_init(struct p9_wstat *stbuf)
  81 {
  82         stbuf->name  = NULL;
  83         stbuf->uid   = NULL;
  84         stbuf->gid   = NULL;
  85         stbuf->muid  = NULL;
  86         stbuf->extension = NULL;
  87 }
  88
  89 /**
  90  * v9fs_alloc_rdir_buf - Allocate buffer used for read and readdir
  91  * @filp: opened file structure
  92  * @buflen: Length in bytes of buffer to allocate
  93  *
  94  */
  95
  96 static int v9fs_alloc_rdir_buf(struct file *filp, int buflen)
  97 {
  98         struct p9_rdir *rdir;
  99         struct p9_fid *fid;
 100         int err = 0;
 101
 102         fid = filp->private_data;
 103         if (!fid->rdir) {
 104                 rdir = kmalloc(sizeof(struct p9_rdir) + buflen, GFP_KERNEL);
 105
 106                 if (rdir == NULL) {
 107                         err = -ENOMEM;
 108                         goto exit;
 109                 }
 110                 spin_lock(&filp->f_dentry->d_lock);
 111                 if (!fid->rdir) {
 112                         rdir->buf = (uint8_t *)rdir + sizeof(struct p9_rdir);
 113                         mutex_init(&rdir->mutex);
 114                         rdir->head = rdir->tail = 0;
 115                         fid->rdir = (void *) rdir;
 116                         rdir = NULL;
 117                 }
 118                 spin_unlock(&filp->f_dentry->d_lock);
 119                 kfree(rdir);
 120         }
 121 exit:
 122         return err;
 123 }
 124
 125 /**
 126  * v9fs_dir_readdir - read a directory
 127  * @filp: opened file structure
 128  * @dirent: directory structure ???
 129  * @filldir: function to populate directory structure ???
 130  *
 131  */
 132
 133 static int v9fs_dir_readdir(struct file *filp, void *dirent, filldir_t filldir)
 134 {
 135         int over;
 136         struct p9_wstat st;
 137         int err = 0;
 138         struct p9_fid *fid;
 139         int buflen;
 140         int reclen = 0;
 141         struct p9_rdir *rdir;
 142
 143         p9_debug(P9_DEBUG_VFS, "name %s\n", filp->f_path.dentry->d_name.name);
 144         fid = filp->private_data;
 145
 146         buflen = fid->clnt->msize - P9_IOHDRSZ;
 147
 148         err = v9fs_alloc_rdir_buf(filp, buflen);
 149         if (err)
 150                 goto exit;
 151         rdir = (struct p9_rdir *) fid->rdir;
 152
 153         err = mutex_lock_interruptible(&rdir->mutex);
 154         if (err)
 155                 return err;
 156         while (err == 0) {
 157                 if (rdir->tail == rdir->head) {
 158                         err = v9fs_file_readn(filp, rdir->buf, NULL,
 159                                                         buflen, filp->f_pos);
 160                         if (err <= 0)
 161                                 goto unlock_and_exit;
 162
 163                         rdir->head = 0;
 164                         rdir->tail = err;
 165                 }
 166                 while (rdir->head < rdir->tail) {
 167                         p9stat_init(&st);
 168                         err = p9stat_read(fid->clnt, rdir->buf + rdir->head,
 169                                           rdir->tail - rdir->head, &st);
 170                         if (err) {
 171                                 p9_debug(P9_DEBUG_VFS, "returned %d\n", err);
 172                                 err = -EIO;
 173                                 p9stat_free(&st);
 174                                 goto unlock_and_exit;
 175                         }
 176                         reclen = st.size+2;
 177
 178                         over = filldir(dirent, st.name, strlen(st.name),
 179                             filp->f_pos, v9fs_qid2ino(&st.qid), dt_type(&st));
 180
 181                         p9stat_free(&st);
 182
 183                         if (over) {
 184                                 err = 0;
 185                                 goto unlock_and_exit;
 186                         }
 187                         rdir->head += reclen;
 188                         filp->f_pos += reclen;
 189                 }
 190         }
 191
 192 unlock_and_exit:
 193         mutex_unlock(&rdir->mutex);
 194 exit:
 195         return err;
 196 }
 197
 198 /**
 199  * v9fs_dir_readdir_dotl - read a directory
 200  * @filp: opened file structure
 201  * @dirent: buffer to fill dirent structures
 202  * @filldir: function to populate dirent structures
 203  *
 204  */
 205 static int v9fs_dir_readdir_dotl(struct file *filp, void *dirent,
 206                                                 filldir_t filldir)
 207 {
 208         int over;
 209         int err = 0;
 210         struct p9_fid *fid;
 211         int buflen;
 212         struct p9_rdir *rdir;
 213         struct p9_dirent curdirent;
 214         u64 oldoffset = 0;
 215
 216         p9_debug(P9_DEBUG_VFS, "name %s\n", filp->f_path.dentry->d_name.name);
 217         fid = filp->private_data;
 218
 219         buflen = fid->clnt->msize - P9_READDIRHDRSZ;
 220
 221         err = v9fs_alloc_rdir_buf(filp, buflen);
 222         if (err)
 223                 goto exit;
 224         rdir = (struct p9_rdir *) fid->rdir;
 225
 226         err = mutex_lock_interruptible(&rdir->mutex);
 227         if (err)
 228                 return err;
 229
 230         while (err == 0) {
 231                 if (rdir->tail == rdir->head) {
 232                         err = p9_client_readdir(fid, rdir->buf, buflen,
 233                                                 filp->f_pos);
 234                         if (err <= 0)
 235                                 goto unlock_and_exit;
 236
 237                         rdir->head = 0;
 238                         rdir->tail = err;
 239                 }
 240
 241                 while (rdir->head < rdir->tail) {
 242
 243                         err = p9dirent_read(fid->clnt, rdir->buf + rdir->head,
 244                                             rdir->tail - rdir->head,
 245                                             &curdirent);
 246                         if (err < 0) {
 247                                 p9_debug(P9_DEBUG_VFS, "returned %d\n", err);
 248                                 err = -EIO;
 249                                 goto unlock_and_exit;
 250                         }
 251
 252                         /* d_off in dirent structure tracks the offset into
 253                          * the next dirent in the dir. However, filldir()
 254                          * expects offset into the current dirent. Hence
 255                          * while calling filldir send the offset from the
 256                          * previous dirent structure.
 257                          */
 258                         over = filldir(dirent, curdirent.d_name,
 259                                         strlen(curdirent.d_name),
 260                                         oldoffset, v9fs_qid2ino(&curdirent.qid),
 261                                         curdirent.d_type);
 262                         oldoffset = curdirent.d_off;
 263
 264                         if (over) {
 265                                 err = 0;
 266                                 goto unlock_and_exit;
 267                         }
 268
 269                         filp->f_pos = curdirent.d_off;
 270                         rdir->head += err;
 271                 }
 272         }
 273
 274 unlock_and_exit:
 275         mutex_unlock(&rdir->mutex);
 276 exit:
 277         return err;
 278 }
 279
 280
 281 /**
 282  * v9fs_dir_release - close a directory
 283  * @inode: inode of the directory
 284  * @filp: file pointer to a directory
 285  *
 286  */
 287
 288 int v9fs_dir_release(struct inode *inode, struct file *filp)
 289 {
 290         struct p9_fid *fid;
 291
 292         fid = filp->private_data;
 293         p9_debug(P9_DEBUG_VFS, "inode: %p filp: %p fid: %d\n",
 294                  inode, filp, fid ? fid->fid : -1);
 295         if (fid)
 296                 p9_client_clunk(fid);
 297         return 0;
 298 }
 299
 300 const struct file_operations v9fs_dir_operations = {
 301         .read = generic_read_dir,
 302         .llseek = generic_file_llseek,
 303         .readdir = v9fs_dir_readdir,
 304         .open = v9fs_file_open,
 305         .release = v9fs_dir_release,
 306 };
 307
 308 const struct file_operations v9fs_dir_operations_dotl = {
 309         .read = generic_read_dir,
 310         .llseek = generic_file_llseek,
 311         .readdir = v9fs_dir_readdir_dotl,
 312         .open = v9fs_file_open,
 313         .release = v9fs_dir_release,
 314         .fsync = v9fs_file_fsync_dotl,
 315 };