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