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.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
  45 static 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 of length %d\n",
 104                        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
 117 failed:
 118         return rc;
 119 }
 120
 121 static void ll_put_link(void *p)
 122 {
 123         ptlrpc_req_finished(p);
 124 }
 125
 126 static const char *ll_get_link(struct dentry *dentry,
 127                                struct inode *inode,
 128                                struct delayed_call *done)
 129 {
 130         struct ptlrpc_request *request = NULL;
 131         int rc;
 132         char *symname = NULL;
 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 struct inode_operations ll_fast_symlink_inode_operations = {
 153         .readlink       = generic_readlink,
 154         .setattr        = ll_setattr,
 155         .get_link       = ll_get_link,
 156         .getattr        = ll_getattr,
 157         .permission     = ll_inode_permission,
 158         .setxattr       = ll_setxattr,
 159         .getxattr       = ll_getxattr,
 160         .listxattr      = ll_listxattr,
 161         .removexattr    = ll_removexattr,
 162 };