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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 
 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 - read a directory
105  * @filp: opened file structure
106  * @dirent: directory structure ???
107  * @filldir: function to populate directory structure ???
108  *
109  */
110 
111 static int v9fs_dir_readdir(struct file *filp, void *dirent, filldir_t filldir)
112 {
113         int over;
114         struct p9_wstat st;
115         int err = 0;
116         struct p9_fid *fid;
117         int buflen;
118         int reclen = 0;
119         struct p9_rdir *rdir;
120 
121         p9_debug(P9_DEBUG_VFS, "name %s\n", filp->f_path.dentry->d_name.name);
122         fid = filp->private_data;
123 
124         buflen = fid->clnt->msize - P9_IOHDRSZ;
125 
126         rdir = v9fs_alloc_rdir_buf(filp, buflen);
127         if (!rdir)
128                 return -ENOMEM;
129 
130         while (1) {
131                 if (rdir->tail == rdir->head) {
132                         err = v9fs_file_readn(filp, rdir->buf, NULL,
133                                                         buflen, filp->f_pos);
134                         if (err <= 0)
135                                 return err;
136 
137                         rdir->head = 0;
138                         rdir->tail = err;
139                 }
140                 while (rdir->head < rdir->tail) {
141                         p9stat_init(&st);
142                         err = p9stat_read(fid->clnt, rdir->buf + rdir->head,
143                                           rdir->tail - rdir->head, &st);
144                         if (err) {
145                                 p9_debug(P9_DEBUG_VFS, "returned %d\n", err);
146                                 p9stat_free(&st);
147                                 return -EIO;
148                         }
149                         reclen = st.size+2;
150 
151                         over = filldir(dirent, st.name, strlen(st.name),
152                             filp->f_pos, v9fs_qid2ino(&st.qid), dt_type(&st));
153 
154                         p9stat_free(&st);
155 
156                         if (over)
157                                 return 0;
158 
159                         rdir->head += reclen;
160                         filp->f_pos += reclen;
161                 }
162         }
163 }
164 
165 /**
166  * v9fs_dir_readdir_dotl - read a directory
167  * @filp: opened file structure
168  * @dirent: buffer to fill dirent structures
169  * @filldir: function to populate dirent structures
170  *
171  */
172 static int v9fs_dir_readdir_dotl(struct file *filp, void *dirent,
173                                                 filldir_t filldir)
174 {
175         int over;
176         int err = 0;
177         struct p9_fid *fid;
178         int buflen;
179         struct p9_rdir *rdir;
180         struct p9_dirent curdirent;
181         u64 oldoffset = 0;
182 
183         p9_debug(P9_DEBUG_VFS, "name %s\n", filp->f_path.dentry->d_name.name);
184         fid = filp->private_data;
185 
186         buflen = fid->clnt->msize - P9_READDIRHDRSZ;
187 
188         rdir = v9fs_alloc_rdir_buf(filp, buflen);
189         if (!rdir)
190                 return -ENOMEM;
191 
192         while (1) {
193                 if (rdir->tail == rdir->head) {
194                         err = p9_client_readdir(fid, rdir->buf, buflen,
195                                                 filp->f_pos);
196                         if (err <= 0)
197                                 return err;
198 
199                         rdir->head = 0;
200                         rdir->tail = err;
201                 }
202 
203                 while (rdir->head < rdir->tail) {
204 
205                         err = p9dirent_read(fid->clnt, rdir->buf + rdir->head,
206                                             rdir->tail - rdir->head,
207                                             &curdirent);
208                         if (err < 0) {
209                                 p9_debug(P9_DEBUG_VFS, "returned %d\n", err);
210                                 return -EIO;
211                         }
212 
213                         /* d_off in dirent structure tracks the offset into
214                          * the next dirent in the dir. However, filldir()
215                          * expects offset into the current dirent. Hence
216                          * while calling filldir send the offset from the
217                          * previous dirent structure.
218                          */
219                         over = filldir(dirent, curdirent.d_name,
220                                         strlen(curdirent.d_name),
221                                         oldoffset, v9fs_qid2ino(&curdirent.qid),
222                                         curdirent.d_type);
223                         oldoffset = curdirent.d_off;
224 
225                         if (over)
226                                 return 0;
227 
228                         filp->f_pos = curdirent.d_off;
229                         rdir->head += err;
230                 }
231         }
232 }
233 
234 
235 /**
236  * v9fs_dir_release - close a directory
237  * @inode: inode of the directory
238  * @filp: file pointer to a directory
239  *
240  */
241 
242 int v9fs_dir_release(struct inode *inode, struct file *filp)
243 {
244         struct p9_fid *fid;
245 
246         fid = filp->private_data;
247         p9_debug(P9_DEBUG_VFS, "inode: %p filp: %p fid: %d\n",
248                  inode, filp, fid ? fid->fid : -1);
249         if (fid)
250                 p9_client_clunk(fid);
251         return 0;
252 }
253 
254 const struct file_operations v9fs_dir_operations = {
255         .read = generic_read_dir,
256         .llseek = generic_file_llseek,
257         .readdir = v9fs_dir_readdir,
258         .open = v9fs_file_open,
259         .release = v9fs_dir_release,
260 };
261 
262 const struct file_operations v9fs_dir_operations_dotl = {
263         .read = generic_read_dir,
264         .llseek = generic_file_llseek,
265         .readdir = v9fs_dir_readdir_dotl,
266         .open = v9fs_file_open,
267         .release = v9fs_dir_release,
268         .fsync = v9fs_file_fsync_dotl,
269 };
270 

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