[GFS2] Fix for root inode ref count bug
[safe/jmp/linux-2.6] / fs / gfs2 / ops_export.c
1 /*
2  * Copyright (C) Sistina Software, Inc.  1997-2003 All rights reserved.
3  * Copyright (C) 2004-2005 Red Hat, Inc.  All rights reserved.
4  *
5  * This copyrighted material is made available to anyone wishing to use,
6  * modify, copy, or redistribute it subject to the terms and conditions
7  * of the GNU General Public License v.2.
8  */
9
10 #include <linux/sched.h>
11 #include <linux/slab.h>
12 #include <linux/spinlock.h>
13 #include <linux/completion.h>
14 #include <linux/buffer_head.h>
15 #include <asm/semaphore.h>
16
17 #include "gfs2.h"
18 #include "dir.h"
19 #include "glock.h"
20 #include "glops.h"
21 #include "inode.h"
22 #include "ops_export.h"
23 #include "rgrp.h"
24
25 static struct dentry *gfs2_decode_fh(struct super_block *sb,
26                                      __u32 *fh,
27                                      int fh_len,
28                                      int fh_type,
29                                      int (*acceptable)(void *context,
30                                                        struct dentry *dentry),
31                                      void *context)
32 {
33         struct gfs2_inum this, parent;
34
35         atomic_inc(&get_v2sdp(sb)->sd_ops_export);
36
37         if (fh_type != fh_len)
38                 return NULL;
39
40         memset(&parent, 0, sizeof(struct gfs2_inum));
41
42         switch (fh_type) {
43         case 8:
44                 parent.no_formal_ino = ((uint64_t)be32_to_cpu(fh[4])) << 32;
45                 parent.no_formal_ino |= be32_to_cpu(fh[5]);
46                 parent.no_addr = ((uint64_t)be32_to_cpu(fh[6])) << 32;
47                 parent.no_addr |= be32_to_cpu(fh[7]);
48         case 4:
49                 this.no_formal_ino = ((uint64_t)be32_to_cpu(fh[0])) << 32;
50                 this.no_formal_ino |= be32_to_cpu(fh[1]);
51                 this.no_addr = ((uint64_t)be32_to_cpu(fh[2])) << 32;
52                 this.no_addr |= be32_to_cpu(fh[3]);
53                 break;
54         default:
55                 return NULL;
56         }
57
58         return gfs2_export_ops.find_exported_dentry(sb, &this, &parent,
59                                                     acceptable, context);
60 }
61
62 static int gfs2_encode_fh(struct dentry *dentry, __u32 *fh, int *len,
63                           int connectable)
64 {
65         struct inode *inode = dentry->d_inode;
66         struct gfs2_inode *ip = get_v2ip(inode);
67         struct gfs2_sbd *sdp = ip->i_sbd;
68
69         atomic_inc(&sdp->sd_ops_export);
70
71         if (*len < 4 || (connectable && *len < 8))
72                 return 255;
73
74         fh[0] = ip->i_num.no_formal_ino >> 32;
75         fh[0] = cpu_to_be32(fh[0]);
76         fh[1] = ip->i_num.no_formal_ino & 0xFFFFFFFF;
77         fh[1] = cpu_to_be32(fh[1]);
78         fh[2] = ip->i_num.no_addr >> 32;
79         fh[2] = cpu_to_be32(fh[2]);
80         fh[3] = ip->i_num.no_addr & 0xFFFFFFFF;
81         fh[3] = cpu_to_be32(fh[3]);
82         *len = 4;
83
84         if (!connectable || ip == get_v2ip(sdp->sd_root_dir))
85                 return *len;
86
87         spin_lock(&dentry->d_lock);
88         inode = dentry->d_parent->d_inode;
89         ip = get_v2ip(inode);
90         gfs2_inode_hold(ip);
91         spin_unlock(&dentry->d_lock);
92
93         fh[4] = ip->i_num.no_formal_ino >> 32;
94         fh[4] = cpu_to_be32(fh[4]);
95         fh[5] = ip->i_num.no_formal_ino & 0xFFFFFFFF;
96         fh[5] = cpu_to_be32(fh[5]);
97         fh[6] = ip->i_num.no_addr >> 32;
98         fh[6] = cpu_to_be32(fh[6]);
99         fh[7] = ip->i_num.no_addr & 0xFFFFFFFF;
100         fh[7] = cpu_to_be32(fh[7]);
101         *len = 8;
102
103         gfs2_inode_put(ip);
104
105         return *len;
106 }
107
108 struct get_name_filldir {
109         struct gfs2_inum inum;
110         char *name;
111 };
112
113 static int get_name_filldir(void *opaque, const char *name, unsigned int length,
114                             uint64_t offset, struct gfs2_inum *inum,
115                             unsigned int type)
116 {
117         struct get_name_filldir *gnfd = (struct get_name_filldir *)opaque;
118
119         if (!gfs2_inum_equal(inum, &gnfd->inum))
120                 return 0;
121
122         memcpy(gnfd->name, name, length);
123         gnfd->name[length] = 0;
124
125         return 1;
126 }
127
128 static int gfs2_get_name(struct dentry *parent, char *name,
129                          struct dentry *child)
130 {
131         struct inode *dir = parent->d_inode;
132         struct inode *inode = child->d_inode;
133         struct gfs2_inode *dip, *ip;
134         struct get_name_filldir gnfd;
135         struct gfs2_holder gh;
136         uint64_t offset = 0;
137         int error;
138
139         if (!dir)
140                 return -EINVAL;
141
142         atomic_inc(&get_v2sdp(dir->i_sb)->sd_ops_export);
143
144         if (!S_ISDIR(dir->i_mode) || !inode)
145                 return -EINVAL;
146
147         dip = get_v2ip(dir);
148         ip = get_v2ip(inode);
149
150         *name = 0;
151         gnfd.inum = ip->i_num;
152         gnfd.name = name;
153
154         error = gfs2_glock_nq_init(dip->i_gl, LM_ST_SHARED, 0, &gh);
155         if (error)
156                 return error;
157
158         error = gfs2_dir_read(dip, &offset, &gnfd, get_name_filldir);
159
160         gfs2_glock_dq_uninit(&gh);
161
162         if (!error && !*name)
163                 error = -ENOENT;
164
165         return error;
166 }
167
168 static struct dentry *gfs2_get_parent(struct dentry *child)
169 {
170         struct gfs2_inode *dip = get_v2ip(child->d_inode);
171         struct qstr dotdot = { .name = "..", .len = 2 };
172         struct inode *inode;
173         struct dentry *dentry;
174         int error;
175
176         atomic_inc(&dip->i_sbd->sd_ops_export);
177
178         error = gfs2_lookupi(child->d_inode, &dotdot, 1, &inode);
179         if (error)
180                 return ERR_PTR(error);
181
182         dentry = d_alloc_anon(inode);
183         if (!dentry) {
184                 iput(inode);
185                 return ERR_PTR(-ENOMEM);
186         }
187
188         return dentry;
189 }
190
191 static struct dentry *gfs2_get_dentry(struct super_block *sb, void *inum_p)
192 {
193         struct gfs2_sbd *sdp = get_v2sdp(sb);
194         struct gfs2_inum *inum = (struct gfs2_inum *)inum_p;
195         struct gfs2_holder i_gh, ri_gh, rgd_gh;
196         struct gfs2_rgrpd *rgd;
197         struct gfs2_inode *ip;
198         struct inode *inode;
199         struct dentry *dentry;
200         int error;
201
202         atomic_inc(&sdp->sd_ops_export);
203
204         /* System files? */
205
206         inode = gfs2_iget(sb, inum);
207         if (inode) {
208                 ip = get_v2ip(inode);
209                 if (ip->i_num.no_formal_ino != inum->no_formal_ino) {
210                         iput(inode);
211                         return ERR_PTR(-ESTALE);
212                 }
213                 goto out_inode;
214         }
215
216         error = gfs2_glock_nq_num(sdp,
217                                   inum->no_addr, &gfs2_inode_glops,
218                                   LM_ST_SHARED, LM_FLAG_ANY | GL_LOCAL_EXCL,
219                                   &i_gh);
220         if (error)
221                 return ERR_PTR(error);
222
223         error = gfs2_inode_get(i_gh.gh_gl, inum, NO_CREATE, &ip);
224         if (error)
225                 goto fail;
226         if (ip)
227                 goto out_ip;
228
229         error = gfs2_rindex_hold(sdp, &ri_gh);
230         if (error)
231                 goto fail;
232
233         error = -EINVAL;
234         rgd = gfs2_blk2rgrpd(sdp, inum->no_addr);
235         if (!rgd)
236                 goto fail_rindex;
237
238         error = gfs2_glock_nq_init(rgd->rd_gl, LM_ST_SHARED, 0, &rgd_gh);
239         if (error)
240                 goto fail_rindex;
241
242         error = -ESTALE;
243         if (gfs2_get_block_type(rgd, inum->no_addr) != GFS2_BLKST_DINODE)
244                 goto fail_rgd;
245
246         gfs2_glock_dq_uninit(&rgd_gh);
247         gfs2_glock_dq_uninit(&ri_gh);
248
249         error = gfs2_inode_get(i_gh.gh_gl, inum, CREATE, &ip);
250         if (error)
251                 goto fail;
252
253         error = gfs2_inode_refresh(ip);
254         if (error) {
255                 gfs2_inode_put(ip);
256                 goto fail;
257         }
258
259         atomic_inc(&sdp->sd_fh2dentry_misses);
260
261  out_ip:
262         error = -EIO;
263         if (ip->i_di.di_flags & GFS2_DIF_SYSTEM) {
264                 gfs2_inode_put(ip);
265                 goto fail;
266         }
267
268         gfs2_glock_dq_uninit(&i_gh);
269
270         inode = gfs2_ip2v(ip);
271         gfs2_inode_put(ip);
272
273         if (!inode)
274                 return ERR_PTR(-ENOMEM);
275
276  out_inode:
277         dentry = d_alloc_anon(inode);
278         if (!dentry) {
279                 iput(inode);
280                 return ERR_PTR(-ENOMEM);
281         }
282
283         return dentry;
284
285  fail_rgd:
286         gfs2_glock_dq_uninit(&rgd_gh);
287
288  fail_rindex:
289         gfs2_glock_dq_uninit(&ri_gh);
290
291  fail:
292         gfs2_glock_dq_uninit(&i_gh);
293         return ERR_PTR(error);
294 }
295
296 struct export_operations gfs2_export_ops = {
297         .decode_fh = gfs2_decode_fh,
298         .encode_fh = gfs2_encode_fh,
299         .get_name = gfs2_get_name,
300         .get_parent = gfs2_get_parent,
301         .get_dentry = gfs2_get_dentry,
302 };
303