lustre/llite/symlink.c

   1 /* -*- mode: c; c-basic-offset: 8; indent-tabs-mode: nil; -*-
   2  * vim:expandtab:shiftwidth=8:tabstop=8:
   3  *
   4  *  Copyright (c) 2002 Cluster File Systems, Inc.
   5  *
   6  *   This file is part of Lustre, http://www.lustre.org.
   7  *
   8  *   Lustre is free software; you can redistribute it and/or
   9  *   modify it under the terms of version 2 of the GNU General Public
  10  *   License as published by the Free Software Foundation.
  11  *
  12  *   Lustre is distributed in the hope that it will be useful,
  13  *   but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  *   GNU General Public License for more details.
  16  *
  17  *   You should have received a copy of the GNU General Public License
  18  *   along with Lustre; if not, write to the Free Software
  19  *   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  20  */
  21
  22 #include <linux/fs.h>
  23 #include <linux/mm.h>
  24 #include <linux/stat.h>
  25 #include <linux/smp_lock.h>
  26 #include <linux/version.h>
  27 #define DEBUG_SUBSYSTEM S_LLITE
  28
  29 #include <lustre_lite.h>
  30 #include "llite_internal.h"
  31
  32 static int ll_readlink_internal(struct inode *inode,
  33                                 struct ptlrpc_request **request, char **symname)
  34 {
  35         struct ll_inode_info *lli = ll_i2info(inode);
  36         struct ll_sb_info *sbi = ll_i2sbi(inode);
  37         int rc, symlen = i_size_read(inode) + 1;
  38         struct mdt_body *body;
  39         struct obd_capa *oc;
  40         ENTRY;
  41
  42         *request = NULL;
  43
  44         if (lli->lli_symlink_name) {
  45                 *symname = lli->lli_symlink_name;
  46                 CDEBUG(D_INODE, "using cached symlink %s\n", *symname);
  47                 RETURN(0);
  48         }
  49
  50         oc = ll_mdscapa_get(inode);
  51         rc = md_getattr(sbi->ll_md_exp, ll_inode2fid(inode), oc,
  52                         OBD_MD_LINKNAME, symlen, request);
  53         capa_put(oc);
  54         if (rc) {
  55                 if (rc != -ENOENT)
  56                         CERROR("inode %lu: rc = %d\n", inode->i_ino, rc);
  57                 GOTO (failed, rc);
  58         }
  59
  60         body = lustre_msg_buf((*request)->rq_repmsg, REPLY_REC_OFF,
  61                               sizeof(*body));
  62         LASSERT(body != NULL);
  63         LASSERT(lustre_rep_swabbed(*request, REPLY_REC_OFF));
  64
  65         if ((body->valid & OBD_MD_LINKNAME) == 0) {
  66                 CERROR("OBD_MD_LINKNAME not set on reply\n");
  67                 GOTO(failed, rc = -EPROTO);
  68         }
  69
  70         LASSERT(symlen != 0);
  71         if (body->eadatasize != symlen) {
  72                 CERROR("inode %lu: symlink length %d not expected %d\n",
  73                         inode->i_ino, body->eadatasize - 1, symlen - 1);
  74                 GOTO(failed, rc = -EPROTO);
  75         }
  76
  77         *symname = lustre_msg_buf((*request)->rq_repmsg, REPLY_REC_OFF + 1,
  78                                   symlen);
  79         if (*symname == NULL ||
  80             strnlen (*symname, symlen) != symlen - 1) {
  81                 /* not full/NULL terminated */
  82                 CERROR("inode %lu: symlink not NULL terminated string"
  83                         "of length %d\n", inode->i_ino, symlen - 1);
  84                 GOTO(failed, rc = -EPROTO);
  85         }
  86
  87         OBD_ALLOC(lli->lli_symlink_name, symlen);
  88         /* do not return an error if we cannot cache the symlink locally */
  89         if (lli->lli_symlink_name) {
  90                 memcpy(lli->lli_symlink_name, *symname, symlen);
  91                 ptlrpc_req_finished (*request);
  92                 *request = NULL;
  93                 *symname = lli->lli_symlink_name;
  94         }
  95
  96         RETURN(0);
  97
  98  failed:
  99         ptlrpc_req_finished (*request);
 100         RETURN (rc);
 101 }
 102
 103 static int ll_readlink(struct dentry *dentry, char *buffer, int buflen)
 104 {
 105         struct inode *inode = dentry->d_inode;
 106         struct ll_inode_info *lli = ll_i2info(inode);
 107         struct ptlrpc_request *request;
 108         char *symname;
 109         int rc;
 110         ENTRY;
 111
 112         CDEBUG(D_VFSTRACE, "VFS Op\n");
 113         /* on symlinks lli_open_sem protects lli_symlink_name allocation/data */
 114         down(&lli->lli_size_sem);
 115         rc = ll_readlink_internal(inode, &request, &symname);
 116         if (rc)
 117                 GOTO(out, rc);
 118
 119         rc = vfs_readlink(dentry, buffer, buflen, symname);
 120         ptlrpc_req_finished(request);
 121  out:
 122         up(&lli->lli_size_sem);
 123         RETURN(rc);
 124 }
 125
 126 #ifdef HAVE_COOKIE_FOLLOW_LINK
 127 # define LL_FOLLOW_LINK_RETURN_TYPE void *
 128 #else
 129 # define LL_FOLLOW_LINK_RETURN_TYPE int
 130 #endif
 131
 132 static LL_FOLLOW_LINK_RETURN_TYPE ll_follow_link(struct dentry *dentry,
 133                                                  struct nameidata *nd)
 134 {
 135         struct inode *inode = dentry->d_inode;
 136         struct ll_inode_info *lli = ll_i2info(inode);
 137 #ifdef HAVE_VFS_INTENT_PATCHES
 138         struct lookup_intent *it = ll_nd2it(nd);
 139 #endif
 140         struct ptlrpc_request *request;
 141         int rc;
 142         char *symname;
 143         ENTRY;
 144
 145 #ifdef HAVE_VFS_INTENT_PATCHES
 146         if (it != NULL) {
 147                 int op = it->it_op;
 148                 int mode = it->it_create_mode;
 149
 150                 ll_intent_release(it);
 151                 it->it_op = op;
 152                 it->it_create_mode = mode;
 153         }
 154 #endif
 155
 156         CDEBUG(D_VFSTRACE, "VFS Op\n");
 157         down(&lli->lli_size_sem);
 158         rc = ll_readlink_internal(inode, &request, &symname);
 159         up(&lli->lli_size_sem);
 160         if (rc) {
 161                 path_release(nd); /* Kernel assumes that ->follow_link()
 162                                      releases nameidata on error */
 163                 GOTO(out, rc);
 164         }
 165
 166 #if (LINUX_VERSION_CODE < KERNEL_VERSION(2,6,8))
 167         rc = vfs_follow_link(nd, symname);
 168 #else
 169 #ifdef HAVE_COOKIE_FOLLOW_LINK
 170         nd_set_link(nd, symname);
 171         /* @symname may contain a pointer to the request message buffer,
 172            we delay request releasing until ll_put_link then. */
 173         RETURN(request);
 174 #else
 175         if (request != NULL) {
 176                 /* falling back to recursive follow link if the request
 177                  * needs to be cleaned up still. */
 178         rc = vfs_follow_link(nd, symname);
 179                 GOTO(out, rc);
 180         }
 181         nd_set_link(nd, symname);
 182         RETURN(0);
 183 #endif
 184 #endif
 185 out:
 186         ptlrpc_req_finished(request);
 187 #ifdef HAVE_COOKIE_FOLLOW_LINK
 188         RETURN(ERR_PTR(rc));
 189 #else
 190         RETURN(rc);
 191 #endif
 192 }
 193
 194 #ifdef HAVE_COOKIE_FOLLOW_LINK
 195 static void ll_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie)
 196 {
 197         ptlrpc_req_finished(cookie);
 198 }
 199 #endif
 200
 201 struct inode_operations ll_fast_symlink_inode_operations = {
 202         .readlink       = ll_readlink,
 203         .setattr        = ll_setattr,
 204 #ifdef HAVE_VFS_INTENT_PATCHES
 205         .setattr_raw    = ll_setattr_raw,
 206 #endif
 207         .follow_link    = ll_follow_link,
 208 #ifdef HAVE_COOKIE_FOLLOW_LINK
 209         .put_link       = ll_put_link,
 210 #endif
 211         .getattr        = ll_getattr,
 212         .permission     = ll_inode_permission,
 213         .setxattr       = ll_setxattr,
 214         .getxattr       = ll_getxattr,
 215         .listxattr      = ll_listxattr,
 216         .removexattr    = ll_removexattr,
 217 };