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 <linux/uio.h>
  37 #include <net/9p/9p.h>
  38 #include <net/9p/client.h>
  39
  40 #include "v9fs.h"
  41 #include "v9fs_vfs.h"
  42 #include "fid.h"
  43
  44 /**
  45  * struct p9_rdir - readdir accounting
  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         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
  66 static 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 static void p9stat_init(struct p9_wstat *stbuf)
  80 {
  81         stbuf->name  = NULL;
  82         stbuf->uid   = NULL;
  83         stbuf->gid   = NULL;
  84         stbuf->muid  = NULL;
  85         stbuf->extension = NULL;
  86 }
  87
  88 /**
  89  * v9fs_alloc_rdir_buf - Allocate buffer used for read and readdir
  90  * @filp: opened file structure
  91  * @buflen: Length in bytes of buffer to allocate
  92  *
  93  */
  94
  95 static struct p9_rdir *v9fs_alloc_rdir_buf(struct file *filp, int buflen)
  96 {
  97         struct p9_fid *fid = filp->private_data;
  98         if (!fid->rdir)
  99                 fid->rdir = kzalloc(sizeof(struct p9_rdir) + buflen, GFP_KERNEL);
 100         return fid->rdir;
 101 }
 102
 103 /**
 104  * v9fs_dir_readdir - iterate through a directory
 105  * @file: opened file structure
 106  * @ctx: actor we feed the entries to
 107  *
 108  */
 109
 110 static int v9fs_dir_readdir(struct file *file, struct dir_context *ctx)
 111 {
 112         bool over;
 113         struct p9_wstat st;
 114         int err = 0;
 115         struct p9_fid *fid;
 116         int buflen;
 117         int reclen = 0;
 118         struct p9_rdir *rdir;
 119         struct kvec kvec;
 120
 121         p9_debug(P9_DEBUG_VFS, "name %pD\n", file);
 122         fid = file->private_data;
 123
 124         buflen = fid->clnt->msize - P9_IOHDRSZ;
 125
 126         rdir = v9fs_alloc_rdir_buf(file, buflen);
 127         if (!rdir)
 128                 return -ENOMEM;
 129         kvec.iov_base = rdir->buf;
 130         kvec.iov_len = buflen;
 131
 132         while (1) {
 133                 if (rdir->tail == rdir->head) {
 134                         struct iov_iter to;
 135                         int n;
 136                         iov_iter_kvec(&to, READ | ITER_KVEC, &kvec, 1, buflen);
 137                         n = p9_client_read(file->private_data, ctx->pos, &to,
 138                                            &err);
 139                         if (err)
 140                                 return err;
 141                         if (n == 0)
 142                                 return 0;
 143
 144                         rdir->head = 0;
 145                         rdir->tail = n;
 146                 }
 147                 while (rdir->head < rdir->tail) {
 148                         p9stat_init(&st);
 149                         err = p9stat_read(fid->clnt, rdir->buf + rdir->head,
 150                                           rdir->tail - rdir->head, &st);
 151                         if (err) {
 152                                 p9_debug(P9_DEBUG_VFS, "returned %d\n", err);
 153                                 p9stat_free(&st);
 154                                 return -EIO;
 155                         }
 156                         reclen = st.size+2;
 157
 158                         over = !dir_emit(ctx, st.name, strlen(st.name),
 159                                          v9fs_qid2ino(&st.qid), dt_type(&st));
 160                         p9stat_free(&st);
 161                         if (over)
 162                                 return 0;
 163
 164                         rdir->head += reclen;
 165                         ctx->pos += reclen;
 166                 }
 167         }
 168 }
 169
 170 /**
 171  * v9fs_dir_readdir_dotl - iterate through a directory
 172  * @file: opened file structure
 173  * @ctx: actor we feed the entries to
 174  *
 175  */
 176 static int v9fs_dir_readdir_dotl(struct file *file, struct dir_context *ctx)
 177 {
 178         int err = 0;
 179         struct p9_fid *fid;
 180         int buflen;
 181         struct p9_rdir *rdir;
 182         struct p9_dirent curdirent;
 183
 184         p9_debug(P9_DEBUG_VFS, "name %pD\n", file);
 185         fid = file->private_data;
 186
 187         buflen = fid->clnt->msize - P9_READDIRHDRSZ;
 188
 189         rdir = v9fs_alloc_rdir_buf(file, buflen);
 190         if (!rdir)
 191                 return -ENOMEM;
 192
 193         while (1) {
 194                 if (rdir->tail == rdir->head) {
 195                         err = p9_client_readdir(fid, rdir->buf, buflen,
 196                                                 ctx->pos);
 197                         if (err <= 0)
 198                                 return err;
 199
 200                         rdir->head = 0;
 201                         rdir->tail = err;
 202                 }
 203
 204                 while (rdir->head < rdir->tail) {
 205
 206                         err = p9dirent_read(fid->clnt, rdir->buf + rdir->head,
 207                                             rdir->tail - rdir->head,
 208                                             &curdirent);
 209                         if (err < 0) {
 210                                 p9_debug(P9_DEBUG_VFS, "returned %d\n", err);
 211                                 return -EIO;
 212                         }
 213
 214                         if (!dir_emit(ctx, curdirent.d_name,
 215                                       strlen(curdirent.d_name),
 216                                       v9fs_qid2ino(&curdirent.qid),
 217                                       curdirent.d_type))
 218                                 return 0;
 219
 220                         ctx->pos = curdirent.d_off;
 221                         rdir->head += err;
 222                 }
 223         }
 224 }
 225
 226
 227 /**
 228  * v9fs_dir_release - close a directory
 229  * @inode: inode of the directory
 230  * @filp: file pointer to a directory
 231  *
 232  */
 233
 234 int v9fs_dir_release(struct inode *inode, struct file *filp)
 235 {
 236         struct p9_fid *fid;
 237
 238         fid = filp->private_data;
 239         p9_debug(P9_DEBUG_VFS, "inode: %p filp: %p fid: %d\n",
 240                  inode, filp, fid ? fid->fid : -1);
 241         if (fid)
 242                 p9_client_clunk(fid);
 243         return 0;
 244 }
 245
 246 const struct file_operations v9fs_dir_operations = {
 247         .read = generic_read_dir,
 248         .llseek = generic_file_llseek,
 249         .iterate_shared = v9fs_dir_readdir,
 250         .open = v9fs_file_open,
 251         .release = v9fs_dir_release,
 252 };
 253
 254 const struct file_operations v9fs_dir_operations_dotl = {
 255         .read = generic_read_dir,
 256         .llseek = generic_file_llseek,
 257         .iterate_shared = v9fs_dir_readdir_dotl,
 258         .open = v9fs_file_open,
 259         .release = v9fs_dir_release,
 260         .fsync = v9fs_file_fsync_dotl,
 261 };