xref: /openbmc/linux/fs/gfs2/export.c (revision 4800cd83)
1 /*
2  * Copyright (C) Sistina Software, Inc.  1997-2003 All rights reserved.
3  * Copyright (C) 2004-2006 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 version 2.
8  */
9 
10 #include <linux/spinlock.h>
11 #include <linux/completion.h>
12 #include <linux/buffer_head.h>
13 #include <linux/exportfs.h>
14 #include <linux/gfs2_ondisk.h>
15 #include <linux/crc32.h>
16 
17 #include "gfs2.h"
18 #include "incore.h"
19 #include "dir.h"
20 #include "glock.h"
21 #include "glops.h"
22 #include "inode.h"
23 #include "super.h"
24 #include "rgrp.h"
25 #include "util.h"
26 
27 #define GFS2_SMALL_FH_SIZE 4
28 #define GFS2_LARGE_FH_SIZE 8
29 #define GFS2_OLD_FH_SIZE 10
30 
31 static int gfs2_encode_fh(struct dentry *dentry, __u32 *p, int *len,
32 			  int connectable)
33 {
34 	__be32 *fh = (__force __be32 *)p;
35 	struct inode *inode = dentry->d_inode;
36 	struct super_block *sb = inode->i_sb;
37 	struct gfs2_inode *ip = GFS2_I(inode);
38 
39 	if (*len < GFS2_SMALL_FH_SIZE ||
40 	    (connectable && *len < GFS2_LARGE_FH_SIZE))
41 		return 255;
42 
43 	fh[0] = cpu_to_be32(ip->i_no_formal_ino >> 32);
44 	fh[1] = cpu_to_be32(ip->i_no_formal_ino & 0xFFFFFFFF);
45 	fh[2] = cpu_to_be32(ip->i_no_addr >> 32);
46 	fh[3] = cpu_to_be32(ip->i_no_addr & 0xFFFFFFFF);
47 	*len = GFS2_SMALL_FH_SIZE;
48 
49 	if (!connectable || inode == sb->s_root->d_inode)
50 		return *len;
51 
52 	spin_lock(&dentry->d_lock);
53 	inode = dentry->d_parent->d_inode;
54 	ip = GFS2_I(inode);
55 	igrab(inode);
56 	spin_unlock(&dentry->d_lock);
57 
58 	fh[4] = cpu_to_be32(ip->i_no_formal_ino >> 32);
59 	fh[5] = cpu_to_be32(ip->i_no_formal_ino & 0xFFFFFFFF);
60 	fh[6] = cpu_to_be32(ip->i_no_addr >> 32);
61 	fh[7] = cpu_to_be32(ip->i_no_addr & 0xFFFFFFFF);
62 	*len = GFS2_LARGE_FH_SIZE;
63 
64 	iput(inode);
65 
66 	return *len;
67 }
68 
69 struct get_name_filldir {
70 	struct gfs2_inum_host inum;
71 	char *name;
72 };
73 
74 static int get_name_filldir(void *opaque, const char *name, int length,
75 			    loff_t offset, u64 inum, unsigned int type)
76 {
77 	struct get_name_filldir *gnfd = opaque;
78 
79 	if (inum != gnfd->inum.no_addr)
80 		return 0;
81 
82 	memcpy(gnfd->name, name, length);
83 	gnfd->name[length] = 0;
84 
85 	return 1;
86 }
87 
88 static int gfs2_get_name(struct dentry *parent, char *name,
89 			 struct dentry *child)
90 {
91 	struct inode *dir = parent->d_inode;
92 	struct inode *inode = child->d_inode;
93 	struct gfs2_inode *dip, *ip;
94 	struct get_name_filldir gnfd;
95 	struct gfs2_holder gh;
96 	u64 offset = 0;
97 	int error;
98 
99 	if (!dir)
100 		return -EINVAL;
101 
102 	if (!S_ISDIR(dir->i_mode) || !inode)
103 		return -EINVAL;
104 
105 	dip = GFS2_I(dir);
106 	ip = GFS2_I(inode);
107 
108 	*name = 0;
109 	gnfd.inum.no_addr = ip->i_no_addr;
110 	gnfd.inum.no_formal_ino = ip->i_no_formal_ino;
111 	gnfd.name = name;
112 
113 	error = gfs2_glock_nq_init(dip->i_gl, LM_ST_SHARED, 0, &gh);
114 	if (error)
115 		return error;
116 
117 	error = gfs2_dir_read(dir, &offset, &gnfd, get_name_filldir);
118 
119 	gfs2_glock_dq_uninit(&gh);
120 
121 	if (!error && !*name)
122 		error = -ENOENT;
123 
124 	return error;
125 }
126 
127 static struct dentry *gfs2_get_parent(struct dentry *child)
128 {
129 	return d_obtain_alias(gfs2_lookupi(child->d_inode, &gfs2_qdotdot, 1));
130 }
131 
132 static struct dentry *gfs2_get_dentry(struct super_block *sb,
133 				      struct gfs2_inum_host *inum)
134 {
135 	struct gfs2_sbd *sdp = sb->s_fs_info;
136 	struct inode *inode;
137 
138 	inode = gfs2_ilookup(sb, inum->no_addr);
139 	if (inode) {
140 		if (GFS2_I(inode)->i_no_formal_ino != inum->no_formal_ino) {
141 			iput(inode);
142 			return ERR_PTR(-ESTALE);
143 		}
144 		goto out_inode;
145 	}
146 
147 	inode = gfs2_lookup_by_inum(sdp, inum->no_addr, &inum->no_formal_ino,
148 				    GFS2_BLKST_DINODE);
149 	if (IS_ERR(inode))
150 		return ERR_CAST(inode);
151 
152 out_inode:
153 	return d_obtain_alias(inode);
154 }
155 
156 static struct dentry *gfs2_fh_to_dentry(struct super_block *sb, struct fid *fid,
157 		int fh_len, int fh_type)
158 {
159 	struct gfs2_inum_host this;
160 	__be32 *fh = (__force __be32 *)fid->raw;
161 
162 	switch (fh_type) {
163 	case GFS2_SMALL_FH_SIZE:
164 	case GFS2_LARGE_FH_SIZE:
165 	case GFS2_OLD_FH_SIZE:
166 		this.no_formal_ino = ((u64)be32_to_cpu(fh[0])) << 32;
167 		this.no_formal_ino |= be32_to_cpu(fh[1]);
168 		this.no_addr = ((u64)be32_to_cpu(fh[2])) << 32;
169 		this.no_addr |= be32_to_cpu(fh[3]);
170 		return gfs2_get_dentry(sb, &this);
171 	default:
172 		return NULL;
173 	}
174 }
175 
176 static struct dentry *gfs2_fh_to_parent(struct super_block *sb, struct fid *fid,
177 		int fh_len, int fh_type)
178 {
179 	struct gfs2_inum_host parent;
180 	__be32 *fh = (__force __be32 *)fid->raw;
181 
182 	switch (fh_type) {
183 	case GFS2_LARGE_FH_SIZE:
184 	case GFS2_OLD_FH_SIZE:
185 		parent.no_formal_ino = ((u64)be32_to_cpu(fh[4])) << 32;
186 		parent.no_formal_ino |= be32_to_cpu(fh[5]);
187 		parent.no_addr = ((u64)be32_to_cpu(fh[6])) << 32;
188 		parent.no_addr |= be32_to_cpu(fh[7]);
189 		return gfs2_get_dentry(sb, &parent);
190 	default:
191 		return NULL;
192 	}
193 }
194 
195 const struct export_operations gfs2_export_ops = {
196 	.encode_fh = gfs2_encode_fh,
197 	.fh_to_dentry = gfs2_fh_to_dentry,
198 	.fh_to_parent = gfs2_fh_to_parent,
199 	.get_name = gfs2_get_name,
200 	.get_parent = gfs2_get_parent,
201 };
202 
203