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         struct ll_fid fid;
  38         struct mds_body *body;
  39         int rc, symlen = inode->i_size + 1;
  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         ll_inode2fid(&fid, inode);
  51         rc = mdc_getattr(sbi->ll_mdc_exp, &fid,
  52                          OBD_MD_LINKNAME, symlen, request);
  53         if (rc) {
  54                 if (rc != -ENOENT)
  55                         CERROR("inode %lu: rc = %d\n", inode->i_ino, rc);
  56                 GOTO (failed, rc);
  57         }
  58
  59         body = lustre_msg_buf((*request)->rq_repmsg, REPLY_REC_OFF,
  60                               sizeof(*body));
  61         LASSERT(body != NULL);
  62         LASSERT_REPSWABBED(*request, REPLY_REC_OFF);
  63
  64         if ((body->valid & OBD_MD_LINKNAME) == 0) {
  65                 CERROR("OBD_MD_LINKNAME not set on reply\n");
  66                 GOTO(failed, rc = -EPROTO);
  67         }
  68
  69         LASSERT(symlen != 0);
  70         if (body->eadatasize != symlen) {
  71                 CERROR("inode %lu: symlink length %d not expected %d\n",
  72                         inode->i_ino, body->eadatasize - 1, symlen - 1);
  73                 GOTO(failed, rc = -EPROTO);
  74         }
  75
  76         *symname = lustre_msg_buf((*request)->rq_repmsg, REPLY_REC_OFF + 1,
  77                                   symlen);
  78         if (*symname == NULL ||
  79             strnlen (*symname, symlen) != symlen - 1) {
  80                 /* not full/NULL terminated */
  81                 CERROR("inode %lu: symlink not NULL terminated string"
  82                         "of length %d\n", inode->i_ino, symlen - 1);
  83                 GOTO(failed, rc = -EPROTO);
  84         }
  85
  86         OBD_ALLOC(lli->lli_symlink_name, symlen);
  87         /* do not return an error if we cannot cache the symlink locally */
  88         if (lli->lli_symlink_name) {
  89                 memcpy(lli->lli_symlink_name, *symname, symlen);
  90                 ptlrpc_req_finished (*request);
  91                 *request = NULL;
  92                 *symname = lli->lli_symlink_name;
  93         }
  94
  95         RETURN(0);
  96
  97  failed:
  98         ptlrpc_req_finished (*request);
  99         RETURN (rc);
 100 }
 101
 102 static int ll_readlink(struct dentry *dentry, char *buffer, int buflen)
 103 {
 104         struct inode *inode = dentry->d_inode;
 105         struct ll_inode_info *lli = ll_i2info(inode);
 106         struct ptlrpc_request *request;
 107         char *symname;
 108         int rc;
 109         ENTRY;
 110
 111         CDEBUG(D_VFSTRACE, "VFS Op\n");
 112         /* on symlinks lli_open_sem protects lli_symlink_name allocation/data */
 113         down(&lli->lli_open_sem);
 114         rc = ll_readlink_internal(inode, &request, &symname);
 115         if (rc)
 116                 GOTO(out, rc);
 117
 118         rc = vfs_readlink(dentry, buffer, buflen, symname);
 119         ptlrpc_req_finished(request);
 120  out:
 121         up(&lli->lli_open_sem);
 122         RETURN(rc);
 123 }
 124
 125 #ifdef HAVE_COOKIE_FOLLOW_LINK
 126 # define LL_FOLLOW_LINK_RETURN_TYPE void *
 127 #else
 128 # define LL_FOLLOW_LINK_RETURN_TYPE int
 129 #endif
 130
 131 static LL_FOLLOW_LINK_RETURN_TYPE ll_follow_link(struct dentry *dentry, struct nameidata *nd)
 132 {
 133         struct inode *inode = dentry->d_inode;
 134         struct ll_inode_info *lli = ll_i2info(inode);
 135 #ifdef LUSTRE_KERNEL_VERSION
 136         struct lookup_intent *it = ll_nd2it(nd);
 137 #endif
 138         struct ptlrpc_request *request;
 139         int rc;
 140         char *symname;
 141         ENTRY;
 142
 143 #ifdef LUSTRE_KERNEL_VERSION
 144         if (it != NULL) {
 145                 int op = it->it_op;
 146                 int mode = it->it_create_mode;
 147
 148                 ll_intent_release(it);
 149                 it->it_op = op;
 150                 it->it_create_mode = mode;
 151         }
 152 #endif
 153
 154         CDEBUG(D_VFSTRACE, "VFS Op\n");
 155         down(&lli->lli_open_sem);
 156         rc = ll_readlink_internal(inode, &request, &symname);
 157         up(&lli->lli_open_sem);
 158         if (rc) {
 159                 path_release(nd); /* Kernel assumes that ->follow_link()
 160                                      releases nameidata on error */
 161                 GOTO(out, rc);
 162         }
 163
 164 #if (LINUX_VERSION_CODE < KERNEL_VERSION(2,6,8))
 165         rc = vfs_follow_link(nd, symname);
 166 #else
 167 # ifdef HAVE_COOKIE_FOLLOW_LINK
 168         nd_set_link(nd, symname);
 169         /* @symname may contain a pointer to the request message buffer,
 170            we delay request releasing until ll_put_link then. */
 171         RETURN(request);
 172 # else
 173         if (request != NULL) {
 174                 /* falling back to recursive follow link if the request
 175                  * needs to be cleaned up still. */
 176                 rc = vfs_follow_link(nd, symname);
 177                 GOTO(out, rc);
 178         }
 179         nd_set_link(nd, symname);
 180         RETURN(0);
 181 # endif
 182 #endif
 183 out:
 184         ptlrpc_req_finished(request);
 185 #ifdef HAVE_COOKIE_FOLLOW_LINK
 186         RETURN(ERR_PTR(rc));
 187 #else
 188         RETURN(rc);
 189 #endif
 190 }
 191
 192 #ifdef HAVE_COOKIE_FOLLOW_LINK
 193 static void ll_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie)
 194 {
 195         ptlrpc_req_finished(cookie);
 196 }
 197 #endif
 198
 199 struct inode_operations ll_fast_symlink_inode_operations = {
 200         .readlink       = ll_readlink,
 201         .setattr        = ll_setattr,
 202 #ifdef LUSTRE_KERNEL_VERSION
 203         .setattr_raw    = ll_setattr_raw,
 204 #endif
 205         .follow_link    = ll_follow_link,
 206 #ifdef HAVE_COOKIE_FOLLOW_LINK
 207         .put_link       = ll_put_link,
 208 #endif
 209 #if (LINUX_VERSION_CODE < KERNEL_VERSION(2,5,0))
 210         .revalidate_it  = ll_inode_revalidate_it,
 211 #else
 212         .getattr        = ll_getattr,
 213 #endif
 214         .permission     = ll_inode_permission,
 215         .setxattr       = ll_setxattr,
 216         .getxattr       = ll_getxattr,
 217         .listxattr      = ll_listxattr,
 218         .removexattr    = ll_removexattr,
 219 };