drivers/staging/lustre/lustre/llite/symlink.c

   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.gnu.org/licenses/gpl-2.0.html
  19  *
  20  * GPL HEADER END
  21  */
  22 /*
  23  * Copyright (c) 2002, 2010, Oracle and/or its affiliates. All rights reserved.
  24  * Use is subject to license terms.
  25  *
  26  * Copyright (c) 2011, 2012, Intel Corporation.
  27  */
  28 /*
  29  * This file is part of Lustre, http://www.lustre.org/
  30  * Lustre is a trademark of Sun Microsystems, Inc.
  31  */
  32
  33 #include <linux/fs.h>
  34 #include <linux/mm.h>
  35 #include <linux/stat.h>
  36 #define DEBUG_SUBSYSTEM S_LLITE
  37
  38 #include "llite_internal.h"
  39
  40 static int ll_readlink_internal(struct inode *inode,
  41                                 struct ptlrpc_request **request, char **symname)
  42 {
  43         struct ll_inode_info *lli = ll_i2info(inode);
  44         struct ll_sb_info *sbi = ll_i2sbi(inode);
  45         int rc, symlen = i_size_read(inode) + 1;
  46         struct mdt_body *body;
  47         struct md_op_data *op_data;
  48
  49         *request = NULL;
  50
  51         if (lli->lli_symlink_name) {
  52                 int print_limit = min_t(int, PAGE_SIZE - 128, symlen);
  53
  54                 *symname = lli->lli_symlink_name;
  55                 /* If the total CDEBUG() size is larger than a page, it
  56                  * will print a warning to the console, avoid this by
  57                  * printing just the last part of the symlink.
  58                  */
  59                 CDEBUG(D_INODE, "using cached symlink %s%.*s, len = %d\n",
  60                        print_limit < symlen ? "..." : "", print_limit,
  61                        (*symname) + symlen - print_limit, symlen);
  62                 return 0;
  63         }
  64
  65         op_data = ll_prep_md_op_data(NULL, inode, NULL, NULL, 0, symlen,
  66                                      LUSTRE_OPC_ANY, NULL);
  67         if (IS_ERR(op_data))
  68                 return PTR_ERR(op_data);
  69
  70         op_data->op_valid = OBD_MD_LINKNAME;
  71         rc = md_getattr(sbi->ll_md_exp, op_data, request);
  72         ll_finish_md_op_data(op_data);
  73         if (rc) {
  74                 if (rc != -ENOENT)
  75                         CERROR("%s: inode "DFID": rc = %d\n",
  76                                ll_get_fsname(inode->i_sb, NULL, 0),
  77                                PFID(ll_inode2fid(inode)), rc);
  78                 goto failed;
  79         }
  80
  81         body = req_capsule_server_get(&(*request)->rq_pill, &RMF_MDT_BODY);
  82         if ((body->mbo_valid & OBD_MD_LINKNAME) == 0) {
  83                 CERROR("OBD_MD_LINKNAME not set on reply\n");
  84                 rc = -EPROTO;
  85                 goto failed;
  86         }
  87
  88         LASSERT(symlen != 0);
  89         if (body->mbo_eadatasize != symlen) {
  90                 CERROR("%s: inode "DFID": symlink length %d not expected %d\n",
  91                        ll_get_fsname(inode->i_sb, NULL, 0),
  92                        PFID(ll_inode2fid(inode)), body->mbo_eadatasize - 1,
  93                        symlen - 1);
  94                 rc = -EPROTO;
  95                 goto failed;
  96         }
  97
  98         *symname = req_capsule_server_get(&(*request)->rq_pill, &RMF_MDT_MD);
  99         if (!*symname ||
 100             strnlen(*symname, symlen) != symlen - 1) {
 101                 /* not full/NULL terminated */
 102                 CERROR("inode %lu: symlink not NULL terminated string of length %d\n",
 103                        inode->i_ino, symlen - 1);
 104                 rc = -EPROTO;
 105                 goto failed;
 106         }
 107
 108         lli->lli_symlink_name = kzalloc(symlen, GFP_NOFS);
 109         /* do not return an error if we cannot cache the symlink locally */
 110         if (lli->lli_symlink_name) {
 111                 memcpy(lli->lli_symlink_name, *symname, symlen);
 112                 *symname = lli->lli_symlink_name;
 113         }
 114         return 0;
 115
 116 failed:
 117         return rc;
 118 }
 119
 120 static void ll_put_link(void *p)
 121 {
 122         ptlrpc_req_finished(p);
 123 }
 124
 125 static const char *ll_get_link(struct dentry *dentry,
 126                                struct inode *inode,
 127                                struct delayed_call *done)
 128 {
 129         struct ptlrpc_request *request = NULL;
 130         int rc;
 131         char *symname = NULL;
 132
 133         if (!dentry)
 134                 return ERR_PTR(-ECHILD);
 135
 136         CDEBUG(D_VFSTRACE, "VFS Op\n");
 137         ll_inode_size_lock(inode);
 138         rc = ll_readlink_internal(inode, &request, &symname);
 139         ll_inode_size_unlock(inode);
 140         if (rc) {
 141                 ptlrpc_req_finished(request);
 142                 return ERR_PTR(rc);
 143         }
 144
 145         /* symname may contain a pointer to the request message buffer,
 146          * we delay request releasing then.
 147          */
 148         set_delayed_call(done, ll_put_link, request);
 149         return symname;
 150 }
 151
 152 const struct inode_operations ll_fast_symlink_inode_operations = {
 153         .setattr        = ll_setattr,
 154         .get_link       = ll_get_link,
 155         .getattr        = ll_getattr,
 156         .permission     = ll_inode_permission,
 157         .listxattr      = ll_listxattr,
 158 };