1/*
2 * GPL HEADER START
3 *
4 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2 only,
8 * as published by the Free Software Foundation.
9 *
10 * This program is distributed in the hope that it will be useful, but
11 * WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
13 * General Public License version 2 for more details (a copy is included
14 * in the LICENSE file that accompanied this code).
15 *
16 * You should have received a copy of the GNU General Public License
17 * version 2 along with this program; If not, see
18 * http://www.sun.com/software/products/lustre/docs/GPLv2.pdf
19 *
20 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
21 * CA 95054 USA or visit www.sun.com if you need additional information or
22 * have any questions.
23 *
24 * GPL HEADER END
25 */
26/*
27 * Copyright (c) 2002, 2010, Oracle and/or its affiliates. All rights reserved.
28 * Use is subject to license terms.
29 *
30 * Copyright (c) 2011, 2012, Intel Corporation.
31 */
32/*
33 * This file is part of Lustre, http://www.lustre.org/
34 * Lustre is a trademark of Sun Microsystems, Inc.
35 */
36
37#include <linux/fs.h>
38#include <linux/mm.h>
39#include <linux/stat.h>
40#define DEBUG_SUBSYSTEM S_LLITE
41
42#include "../include/lustre_lite.h"
43#include "llite_internal.h"
44
45static int ll_readlink_internal(struct inode *inode,
46				struct ptlrpc_request **request, char **symname)
47{
48	struct ll_inode_info *lli = ll_i2info(inode);
49	struct ll_sb_info *sbi = ll_i2sbi(inode);
50	int rc, symlen = i_size_read(inode) + 1;
51	struct mdt_body *body;
52	struct md_op_data *op_data;
53
54	*request = NULL;
55
56	if (lli->lli_symlink_name) {
57		int print_limit = min_t(int, PAGE_SIZE - 128, symlen);
58
59		*symname = lli->lli_symlink_name;
60		/* If the total CDEBUG() size is larger than a page, it
61		 * will print a warning to the console, avoid this by
62		 * printing just the last part of the symlink. */
63		CDEBUG(D_INODE, "using cached symlink %s%.*s, len = %d\n",
64		       print_limit < symlen ? "..." : "", print_limit,
65		       (*symname) + symlen - print_limit, symlen);
66		return 0;
67	}
68
69	op_data = ll_prep_md_op_data(NULL, inode, NULL, NULL, 0, symlen,
70				     LUSTRE_OPC_ANY, NULL);
71	if (IS_ERR(op_data))
72		return PTR_ERR(op_data);
73
74	op_data->op_valid = OBD_MD_LINKNAME;
75	rc = md_getattr(sbi->ll_md_exp, op_data, request);
76	ll_finish_md_op_data(op_data);
77	if (rc) {
78		if (rc != -ENOENT)
79			CERROR("inode %lu: rc = %d\n", inode->i_ino, rc);
80		goto failed;
81	}
82
83	body = req_capsule_server_get(&(*request)->rq_pill, &RMF_MDT_BODY);
84	LASSERT(body != NULL);
85	if ((body->valid & OBD_MD_LINKNAME) == 0) {
86		CERROR("OBD_MD_LINKNAME not set on reply\n");
87		rc = -EPROTO;
88		goto failed;
89	}
90
91	LASSERT(symlen != 0);
92	if (body->eadatasize != symlen) {
93		CERROR("inode %lu: symlink length %d not expected %d\n",
94			inode->i_ino, body->eadatasize - 1, symlen - 1);
95		rc = -EPROTO;
96		goto failed;
97	}
98
99	*symname = req_capsule_server_get(&(*request)->rq_pill, &RMF_MDT_MD);
100	if (*symname == NULL ||
101	    strnlen(*symname, symlen) != symlen - 1) {
102		/* not full/NULL terminated */
103		CERROR("inode %lu: symlink not NULL terminated string"
104			"of length %d\n", inode->i_ino, symlen - 1);
105		rc = -EPROTO;
106		goto failed;
107	}
108
109	lli->lli_symlink_name = kzalloc(symlen, GFP_NOFS);
110	/* do not return an error if we cannot cache the symlink locally */
111	if (lli->lli_symlink_name) {
112		memcpy(lli->lli_symlink_name, *symname, symlen);
113		*symname = lli->lli_symlink_name;
114	}
115	return 0;
116
117failed:
118	return rc;
119}
120
121static void *ll_follow_link(struct dentry *dentry, struct nameidata *nd)
122{
123	struct inode *inode = dentry->d_inode;
124	struct ptlrpc_request *request = NULL;
125	int rc;
126	char *symname = NULL;
127
128	CDEBUG(D_VFSTRACE, "VFS Op\n");
129	/* Limit the recursive symlink depth to 5 instead of default
130	 * 8 links when kernel has 4k stack to prevent stack overflow.
131	 * For 8k stacks we need to limit it to 7 for local servers. */
132	if (THREAD_SIZE < 8192 && current->link_count >= 6) {
133		rc = -ELOOP;
134	} else if (THREAD_SIZE == 8192 && current->link_count >= 8) {
135		rc = -ELOOP;
136	} else {
137		ll_inode_size_lock(inode);
138		rc = ll_readlink_internal(inode, &request, &symname);
139		ll_inode_size_unlock(inode);
140	}
141	if (rc) {
142		ptlrpc_req_finished(request);
143		request = NULL;
144		symname = ERR_PTR(rc);
145	}
146
147	nd_set_link(nd, symname);
148	/* symname may contain a pointer to the request message buffer,
149	 * we delay request releasing until ll_put_link then.
150	 */
151	return request;
152}
153
154static void ll_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie)
155{
156	ptlrpc_req_finished(cookie);
157}
158
159struct inode_operations ll_fast_symlink_inode_operations = {
160	.readlink	= generic_readlink,
161	.setattr	= ll_setattr,
162	.follow_link	= ll_follow_link,
163	.put_link	= ll_put_link,
164	.getattr	= ll_getattr,
165	.permission	= ll_inode_permission,
166	.setxattr	= ll_setxattr,
167	.getxattr	= ll_getxattr,
168	.listxattr	= ll_listxattr,
169	.removexattr	= ll_removexattr,
170};
171