linux/fs/9p/vfs_dir.c
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   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
  54struct 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
  67static 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
  80static 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
  96static 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        }
 121exit:
 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
 133static 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
 192unlock_and_exit:
 193        mutex_unlock(&rdir->mutex);
 194exit:
 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 */
 205static 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
 274unlock_and_exit:
 275        mutex_unlock(&rdir->mutex);
 276exit:
 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
 288int 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
 300const 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
 308const 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};
 316
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