fs/ocfs2/symlink.c

   1 /* -*- mode: c; c-basic-offset: 8; -*-
   2  * vim: noexpandtab sw=8 ts=8 sts=0:
   3  *
   4  *  linux/cluster/ssi/cfs/symlink.c
   5  *
   6  *      This program is free software; you can redistribute it and/or
   7  *      modify it under the terms of the GNU General Public License as
   8  *      published by the Free Software Foundation; either version 2 of
   9  *      the License, or (at your option) any later version.
  10  *
  11  *      This program is distributed in the hope that it will be useful,
  12  *      but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  *      MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE
  14  *      or NON INFRINGEMENT.  See the GNU General Public License for more
  15  *      details.
  16  *
  17  *      You should have received a copy of the GNU General Public License
  18  *      along with this program; if not, write to the Free Software
  19  *      Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  20  *
  21  *      Questions/Comments/Bugfixes to ssic-linux-devel@lists.sourceforge.net
  22  *
  23  *  Copyright (C) 1992  Rick Sladkey
  24  *
  25  *  Optimization changes Copyright (C) 1994 Florian La Roche
  26  *
  27  *  Jun 7 1999, cache symlink lookups in the page cache.  -DaveM
  28  *
  29  *  Portions Copyright (C) 2001 Compaq Computer Corporation
  30  *
  31  *  ocfs2 symlink handling code.
  32  *
  33  *  Copyright (C) 2004, 2005 Oracle.
  34  *
  35  */
  36
  37 #include <linux/fs.h>
  38 #include <linux/types.h>
  39 #include <linux/slab.h>
  40 #include <linux/pagemap.h>
  41 #include <linux/utsname.h>
  42
  43 #define MLOG_MASK_PREFIX ML_NAMEI
  44 #include <cluster/masklog.h>
  45
  46 #include "ocfs2.h"
  47
  48 #include "alloc.h"
  49 #include "file.h"
  50 #include "inode.h"
  51 #include "journal.h"
  52 #include "symlink.h"
  53
  54 #include "buffer_head_io.h"
  55
  56 static char *ocfs2_page_getlink(struct dentry * dentry,
  57                                 struct page **ppage);
  58 static char *ocfs2_fast_symlink_getlink(struct inode *inode,
  59                                         struct buffer_head **bh);
  60
  61 /* get the link contents into pagecache */
  62 static char *ocfs2_page_getlink(struct dentry * dentry,
  63                                 struct page **ppage)
  64 {
  65         struct page * page;
  66         struct address_space *mapping = dentry->d_inode->i_mapping;
  67         page = read_mapping_page(mapping, 0, NULL);
  68         if (IS_ERR(page))
  69                 goto sync_fail;
  70         *ppage = page;
  71         return kmap(page);
  72
  73 sync_fail:
  74         return (char*)page;
  75 }
  76
  77 static char *ocfs2_fast_symlink_getlink(struct inode *inode,
  78                                         struct buffer_head **bh)
  79 {
  80         int status;
  81         char *link = NULL;
  82         struct ocfs2_dinode *fe;
  83
  84         mlog_entry_void();
  85
  86         status = ocfs2_read_block(OCFS2_SB(inode->i_sb),
  87                                   OCFS2_I(inode)->ip_blkno,
  88                                   bh,
  89                                   OCFS2_BH_CACHED,
  90                                   inode);
  91         if (status < 0) {
  92                 mlog_errno(status);
  93                 link = ERR_PTR(status);
  94                 goto bail;
  95         }
  96
  97         fe = (struct ocfs2_dinode *) (*bh)->b_data;
  98         link = (char *) fe->id2.i_symlink;
  99 bail:
 100         mlog_exit(status);
 101
 102         return link;
 103 }
 104
 105 static int ocfs2_readlink(struct dentry *dentry,
 106                           char __user *buffer,
 107                           int buflen)
 108 {
 109         int ret;
 110         char *link;
 111         struct buffer_head *bh = NULL;
 112         struct inode *inode = dentry->d_inode;
 113
 114         mlog_entry_void();
 115
 116         link = ocfs2_fast_symlink_getlink(inode, &bh);
 117         if (IS_ERR(link)) {
 118                 ret = PTR_ERR(link);
 119                 goto out;
 120         }
 121
 122         /*
 123          * Without vfsmount we can't update atime now,
 124          * but we will update atime here ultimately.
 125          */
 126         ret = vfs_readlink(dentry, buffer, buflen, link);
 127
 128         brelse(bh);
 129 out:
 130         mlog_exit(ret);
 131         return ret;
 132 }
 133
 134 static void *ocfs2_follow_link(struct dentry *dentry,
 135                                struct nameidata *nd)
 136 {
 137         int status;
 138         char *link;
 139         struct inode *inode = dentry->d_inode;
 140         struct page *page = NULL;
 141         struct buffer_head *bh = NULL;
 142
 143         if (ocfs2_inode_is_fast_symlink(inode))
 144                 link = ocfs2_fast_symlink_getlink(inode, &bh);
 145         else
 146                 link = ocfs2_page_getlink(dentry, &page);
 147         if (IS_ERR(link)) {
 148                 status = PTR_ERR(link);
 149                 mlog_errno(status);
 150                 goto bail;
 151         }
 152
 153         status = vfs_follow_link(nd, link);
 154
 155 bail:
 156         if (page) {
 157                 kunmap(page);
 158                 page_cache_release(page);
 159         }
 160         if (bh)
 161                 brelse(bh);
 162
 163         return ERR_PTR(status);
 164 }
 165
 166 const struct inode_operations ocfs2_symlink_inode_operations = {
 167         .readlink       = page_readlink,
 168         .follow_link    = ocfs2_follow_link,
 169         .getattr        = ocfs2_getattr,
 170 };
 171 const struct inode_operations ocfs2_fast_symlink_inode_operations = {
 172         .readlink       = ocfs2_readlink,
 173         .follow_link    = ocfs2_follow_link,
 174         .getattr        = ocfs2_getattr,
 175 };