1 /*
2 * fs/isofs/export.c
3 *
4 * (C) 2004 Paul Serice - The new inode scheme requires switching
5 * from iget() to iget5_locked() which means
6 * the NFS export operations have to be hand
7 * coded because the default routines rely on
8 * iget().
9 *
10 * The following files are helpful:
11 *
12 * Documentation/filesystems/Exporting
13 * fs/exportfs/expfs.c.
14 */
15
16 #include <linux/buffer_head.h>
17 #include <linux/errno.h>
18 #include <linux/fs.h>
19 #include <linux/iso_fs.h>
20 #include <linux/kernel.h>
21
22 static struct dentry *
23 isofs_export_iget(struct super_block *sb,
24 unsigned long block,
25 unsigned long offset,
26 __u32 generation)
27 {
28 struct inode *inode;
29 struct dentry *result;
30 if (block == 0)
31 return ERR_PTR(-ESTALE);
32 inode = isofs_iget(sb, block, offset);
33 if (inode == NULL)
34 return ERR_PTR(-ENOMEM);
35 if (is_bad_inode(inode)
36 || (generation && inode->i_generation != generation))
37 {
38 iput(inode);
39 return ERR_PTR(-ESTALE);
40 }
41 result = d_alloc_anon(inode);
42 if (!result) {
43 iput(inode);
44 return ERR_PTR(-ENOMEM);
45 }
46 return result;
47 }
48
49 static struct dentry *
50 isofs_export_get_dentry(struct super_block *sb, void *vobjp)
51 {
52 __u32 *objp = vobjp;
53 unsigned long block = objp[0];
54 unsigned long offset = objp[1];
55 __u32 generation = objp[2];
56 return isofs_export_iget(sb, block, offset, generation);
57 }
58
59 /* This function is surprisingly simple. The trick is understanding
60 * that "child" is always a directory. So, to find its parent, you
61 * simply need to find its ".." entry, normalize its block and offset,
62 * and return the underlying inode. See the comments for
63 * isofs_normalize_block_and_offset(). */
64 static struct dentry *isofs_export_get_parent(struct dentry *child)
65 {
66 unsigned long parent_block = 0;
67 unsigned long parent_offset = 0;
68 struct inode *child_inode = child->d_inode;
69 struct iso_inode_info *e_child_inode = ISOFS_I(child_inode);
70 struct inode *parent_inode = NULL;
71 struct iso_directory_record *de = NULL;
72 struct buffer_head * bh = NULL;
73 struct dentry *rv = NULL;
74
75 /* "child" must always be a directory. */
76 if (!S_ISDIR(child_inode->i_mode)) {
77 printk(KERN_ERR "isofs: isofs_export_get_parent(): "
78 "child is not a directory!\n");
79 rv = ERR_PTR(-EACCES);
80 goto out;
81 }
82
83 /* It is an invariant that the directory offset is zero. If
84 * it is not zero, it means the directory failed to be
85 * normalized for some reason. */
86 if (e_child_inode->i_iget5_offset != 0) {
87 printk(KERN_ERR "isofs: isofs_export_get_parent(): "
88 "child directory not normalized!\n");
89 rv = ERR_PTR(-EACCES);
90 goto out;
91 }
92
93 /* The child inode has been normalized such that its
94 * i_iget5_block value points to the "." entry. Fortunately,
95 * the ".." entry is located in the same block. */
96 parent_block = e_child_inode->i_iget5_block;
97
98 /* Get the block in question. */
99 bh = sb_bread(child_inode->i_sb, parent_block);
100 if (bh == NULL) {
101 rv = ERR_PTR(-EACCES);
102 goto out;
103 }
104
105 /* This is the "." entry. */
106 de = (struct iso_directory_record*)bh->b_data;
107
108 /* The ".." entry is always the second entry. */
109 parent_offset = (unsigned long)isonum_711(de->length);
110 de = (struct iso_directory_record*)(bh->b_data + parent_offset);
111
112 /* Verify it is in fact the ".." entry. */
113 if ((isonum_711(de->name_len) != 1) || (de->name[0] != 1)) {
114 printk(KERN_ERR "isofs: Unable to find the \"..\" "
115 "directory for NFS.\n");
116 rv = ERR_PTR(-EACCES);
117 goto out;
118 }
119
120 /* Normalize */
121 isofs_normalize_block_and_offset(de, &parent_block, &parent_offset);
122
123 /* Get the inode. */
124 parent_inode = isofs_iget(child_inode->i_sb,
125 parent_block,
126 parent_offset);
127 if (parent_inode == NULL) {
128 rv = ERR_PTR(-EACCES);
129 goto out;
130 }
131
132 /* Allocate the dentry. */
133 rv = d_alloc_anon(parent_inode);
134 if (rv == NULL) {
135 rv = ERR_PTR(-ENOMEM);
136 goto out;
137 }
138
139 out:
140 if (bh) {
141 brelse(bh);
142 }
143 return rv;
144 }
145
146 static int
147 isofs_export_encode_fh(struct dentry *dentry,
148 __u32 *fh32,
149 int *max_len,
150 int connectable)
151 {
152 struct inode * inode = dentry->d_inode;
153 struct iso_inode_info * ei = ISOFS_I(inode);
154 int len = *max_len;
155 int type = 1;
156 __u16 *fh16 = (__u16*)fh32;
157
158 /*
159 * WARNING: max_len is 5 for NFSv2. Because of this
160 * limitation, we use the lower 16 bits of fh32[1] to hold the
161 * offset of the inode and the upper 16 bits of fh32[1] to
162 * hold the offset of the parent.
163 */
164
165 if (len < 3 || (connectable && len < 5))
166 return 255;
167
168 len = 3;
169 fh32[0] = ei->i_iget5_block;
170 fh16[2] = (__u16)ei->i_iget5_offset; /* fh16 [sic] */
171 fh32[2] = inode->i_generation;
172 if (connectable && !S_ISDIR(inode->i_mode)) {
173 struct inode *parent;
174 struct iso_inode_info *eparent;
175 spin_lock(&dentry->d_lock);
176 parent = dentry->d_parent->d_inode;
177 eparent = ISOFS_I(parent);
178 fh32[3] = eparent->i_iget5_block;
179 fh16[3] = (__u16)eparent->i_iget5_offset; /* fh16 [sic] */
180 fh32[4] = parent->i_generation;
181 spin_unlock(&dentry->d_lock);
182 len = 5;
183 type = 2;
184 }
185 *max_len = len;
186 return type;
187 }
188
189
190 static struct dentry *
191 isofs_export_decode_fh(struct super_block *sb,
192 __u32 *fh32,
193 int fh_len,
194 int fileid_type,
195 int (*acceptable)(void *context, struct dentry *de),
196 void *context)
197 {
198 __u16 *fh16 = (__u16*)fh32;
199 __u32 child[3]; /* The child is what triggered all this. */
200 __u32 parent[3]; /* The parent is just along for the ride. */
201
202 if (fh_len < 3 || fileid_type > 2)
203 return NULL;
204
205 child[0] = fh32[0];
206 child[1] = fh16[2]; /* fh16 [sic] */
207 child[2] = fh32[2];
208
209 parent[0] = 0;
210 parent[1] = 0;
211 parent[2] = 0;
212 if (fileid_type == 2) {
213 if (fh_len > 2) parent[0] = fh32[3];
214 parent[1] = fh16[3]; /* fh16 [sic] */
215 if (fh_len > 4) parent[2] = fh32[4];
216 }
217
218 return sb->s_export_op->find_exported_dentry(sb, child, parent,
219 acceptable, context);
220 }
221
222
223 struct export_operations isofs_export_ops = {
224 .decode_fh = isofs_export_decode_fh,
225 .encode_fh = isofs_export_encode_fh,
226 .get_dentry = isofs_export_get_dentry,
227 .get_parent = isofs_export_get_parent,
228 };
229
|
This page was automatically generated by the
LXR engine.
|