LXR linux/fs/9p/vfs

   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 <net/9p/9p.h>
  36#include <net/9p/client.h>
  37
  38#include "v9fs.h"
  39#include "v9fs_vfs.h"
  40#include "fid.h"
  41
  42/**
  43 * struct p9_rdir - readdir accounting
  44 * @mutex: mutex protecting readdir
  45 * @head: start offset of current dirread buffer
  46 * @tail: end offset of current dirread buffer
  47 * @buf: dirread buffer
  48 *
  49 * private structure for keeping track of readdir
  50 * allocated on demand
  51 */
  52
  53struct p9_rdir {
  54        struct mutex mutex;
  55        int head;
  56        int tail;
  57        uint8_t *buf;
  58};
  59
  60/**
  61 * dt_type - return file type
  62 * @mistat: mistat structure
  63 *
  64 */
  65
  66static inline int dt_type(struct p9_wstat *mistat)
  67{
  68        unsigned long perm = mistat->mode;
  69        int rettype = DT_REG;
  70
  71        if (perm & P9_DMDIR)
  72                rettype = DT_DIR;
  73        if (perm & P9_DMSYMLINK)
  74                rettype = DT_LNK;
  75
  76        return rettype;
  77}
  78
  79/**
  80 * v9fs_dir_readdir - read a directory
  81 * @filp: opened file structure
  82 * @dirent: directory structure ???
  83 * @filldir: function to populate directory structure ???
  84 *
  85 */
  86
  87static int v9fs_dir_readdir(struct file *filp, void *dirent, filldir_t filldir)
  88{
  89        int over;
  90        struct p9_wstat st;
  91        int err = 0;
  92        struct p9_fid *fid;
  93        int buflen;
  94        int reclen = 0;
  95        struct p9_rdir *rdir;
  96
  97        P9_DPRINTK(P9_DEBUG_VFS, "name %s\n", filp->f_path.dentry->d_name.name);
  98        fid = filp->private_data;
  99
 100        buflen = fid->clnt->msize - P9_IOHDRSZ;
 101
 102        /* allocate rdir on demand */
 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        rdir = (struct p9_rdir *) fid->rdir;
 122
 123        err = mutex_lock_interruptible(&rdir->mutex);
 124        while (err == 0) {
 125                if (rdir->tail == rdir->head) {
 126                        err = v9fs_file_readn(filp, rdir->buf, NULL,
 127                                                        buflen, filp->f_pos);
 128                        if (err <= 0)
 129                                goto unlock_and_exit;
 130
 131                        rdir->head = 0;
 132                        rdir->tail = err;
 133                }
 134
 135                while (rdir->head < rdir->tail) {
 136                        err = p9stat_read(rdir->buf + rdir->head,
 137                                                buflen - rdir->head, &st,
 138                                                fid->clnt->dotu);
 139                        if (err) {
 140                                P9_DPRINTK(P9_DEBUG_VFS, "returned %d\n", err);
 141                                err = -EIO;
 142                                p9stat_free(&st);
 143                                goto unlock_and_exit;
 144                        }
 145                        reclen = st.size+2;
 146
 147                        over = filldir(dirent, st.name, strlen(st.name),
 148                            filp->f_pos, v9fs_qid2ino(&st.qid), dt_type(&st));
 149
 150                        p9stat_free(&st);
 151
 152                        if (over) {
 153                                err = 0;
 154                                goto unlock_and_exit;
 155                        }
 156                        rdir->head += reclen;
 157                        filp->f_pos += reclen;
 158                }
 159        }
 160
 161unlock_and_exit:
 162        mutex_unlock(&rdir->mutex);
 163exit:
 164        return err;
 165}
 166
 167
 168/**
 169 * v9fs_dir_release - close a directory
 170 * @inode: inode of the directory
 171 * @filp: file pointer to a directory
 172 *
 173 */
 174
 175int v9fs_dir_release(struct inode *inode, struct file *filp)
 176{
 177        struct p9_fid *fid;
 178
 179        fid = filp->private_data;
 180        P9_DPRINTK(P9_DEBUG_VFS,
 181                        "inode: %p filp: %p fid: %d\n", inode, filp, fid->fid);
 182        filemap_write_and_wait(inode->i_mapping);
 183        p9_client_clunk(fid);
 184        return 0;
 185}
 186
 187const struct file_operations v9fs_dir_operations = {
 188        .read = generic_read_dir,
 189        .llseek = generic_file_llseek,
 190        .readdir = v9fs_dir_readdir,
 191        .open = v9fs_file_open,
 192        .release = v9fs_dir_release,
 193};
 194