xref: /openbmc/linux/fs/9p/vfs_dir.c (revision 9d56dd3b083a3bec56e9da35ce07baca81030b03)
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 
53 struct 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 
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_dir_readdir - read a directory
81  * @filp: opened file structure
82  * @dirent: directory structure ???
83  * @filldir: function to populate directory structure ???
84  *
85  */
86 
87 static 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 
161 unlock_and_exit:
162 	mutex_unlock(&rdir->mutex);
163 exit:
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 
175 int 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 
187 const 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