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 #define DEBUG_SUBSYSTEM S_LLITE
  23
  24 #include <linux/lustre_lite.h>
  25
  26 static int ll_readlink_internal(struct inode *inode,
  27                                 struct ptlrpc_request **request, char **symname)
  28 {
  29         struct ll_inode_info *lli = ll_i2info(inode);
  30         struct ll_sb_info *sbi = ll_i2sbi(inode);
  31         int rc, len = inode->i_size + 1;
  32         ENTRY;
  33
  34         *request = NULL;
  35
  36         if (lli->lli_symlink_name) {
  37                 *symname = lli->lli_symlink_name;
  38                 CDEBUG(D_INODE, "using cached symlink %s\n", *symname);
  39                 RETURN(0);
  40         }
  41
  42         rc = mdc_getattr(&sbi->ll_mdc_conn, inode->i_ino, S_IFLNK,
  43                          OBD_MD_LINKNAME, len, request);
  44         if (rc) {
  45                 CERROR("inode "LPD64": rc = %d\n", inode->i_ino, rc);
  46                 RETURN(rc);
  47         }
  48
  49         *symname = lustre_msg_buf((*request)->rq_repmsg, 1);
  50
  51         OBD_ALLOC(lli->lli_symlink_name, len);
  52         /* do not return an error if we cannot cache the symlink locally */
  53         if (lli->lli_symlink_name)
  54                 memcpy(lli->lli_symlink_name, *symname, len);
  55
  56         RETURN(0);
  57 }
  58
  59 static int ll_readlink(struct dentry *dentry, char *buffer, int buflen)
  60 {
  61         struct inode *inode = dentry->d_inode;
  62         struct ll_inode_info *lli = ll_i2info(inode);
  63         struct ptlrpc_request *request;
  64         char *symname;
  65         int rc;
  66         ENTRY;
  67
  68         /* on symlinks lli_open_sem protects lli_symlink_name allocation/data */
  69         down(&lli->lli_open_sem);
  70         rc = ll_readlink_internal(inode, &request, &symname);
  71         if (rc)
  72                 GOTO(out, rc);
  73
  74         rc = vfs_readlink(dentry, buffer, buflen, symname);
  75  out:
  76         up(&lli->lli_open_sem);
  77         ptlrpc_free_req(request);
  78
  79         RETURN(rc);
  80 }
  81
  82 static int ll_follow_link(struct dentry *dentry, struct nameidata *nd)
  83 {
  84         struct inode *inode = dentry->d_inode;
  85         struct ll_inode_info *lli = ll_i2info(inode);
  86         struct ptlrpc_request *request;
  87         char *symname;
  88         int rc;
  89         ENTRY;
  90
  91         down(&lli->lli_open_sem);
  92         rc = ll_readlink_internal(inode, &request, &symname);
  93         if (rc)
  94                 GOTO(out, rc);
  95
  96         rc = vfs_follow_link(nd, symname);
  97  out:
  98         up(&lli->lli_open_sem);
  99         ptlrpc_free_req(request);
 100
 101         RETURN(rc);
 102 }
 103
 104 extern int ll_setattr(struct dentry *de, struct iattr *attr);
 105 struct inode_operations ll_fast_symlink_inode_operations = {
 106         readlink:       ll_readlink,
 107         setattr:        ll_setattr,
 108         follow_link:    ll_follow_link
 109 };