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