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         wait_on_page_locked(page);
  71         if (!PageUptodate(page))
  72                 goto async_fail;
  73         *ppage = page;
  74         return kmap(page);
  75
  76 async_fail:
  77         page_cache_release(page);
  78         return ERR_PTR(-EIO);
  79
  80 sync_fail:
  81         return (char*)page;
  82 }
  83
  84 static char *ocfs2_fast_symlink_getlink(struct inode *inode,
  85                                         struct buffer_head **bh)
  86 {
  87         int status;
  88         char *link = NULL;
  89         struct ocfs2_dinode *fe;
  90
  91         mlog_entry_void();
  92
  93         status = ocfs2_read_block(OCFS2_SB(inode->i_sb),
  94                                   OCFS2_I(inode)->ip_blkno,
  95                                   bh,
  96                                   OCFS2_BH_CACHED,
  97                                   inode);
  98         if (status < 0) {
  99                 mlog_errno(status);
 100                 link = ERR_PTR(status);
 101                 goto bail;
 102         }
 103
 104         fe = (struct ocfs2_dinode *) (*bh)->b_data;
 105         link = (char *) fe->id2.i_symlink;
 106 bail:
 107         mlog_exit(status);
 108
 109         return link;
 110 }
 111
 112 static int ocfs2_readlink(struct dentry *dentry,
 113                           char __user *buffer,
 114                           int buflen)
 115 {
 116         int ret;
 117         char *link;
 118         struct buffer_head *bh = NULL;
 119         struct inode *inode = dentry->d_inode;
 120
 121         mlog_entry_void();
 122
 123         link = ocfs2_fast_symlink_getlink(inode, &bh);
 124         if (IS_ERR(link)) {
 125                 ret = PTR_ERR(link);
 126                 goto out;
 127         }
 128
 129         /*
 130          * Without vfsmount we can't update atime now,
 131          * but we will update atime here ultimately.
 132          */
 133         ret = vfs_readlink(dentry, buffer, buflen, link);
 134
 135         brelse(bh);
 136 out:
 137         mlog_exit(ret);
 138         return ret;
 139 }
 140
 141 static void *ocfs2_follow_link(struct dentry *dentry,
 142                                struct nameidata *nd)
 143 {
 144         int status;
 145         char *link;
 146         struct inode *inode = dentry->d_inode;
 147         struct page *page = NULL;
 148         struct buffer_head *bh = NULL;
 149
 150         if (ocfs2_inode_is_fast_symlink(inode))
 151                 link = ocfs2_fast_symlink_getlink(inode, &bh);
 152         else
 153                 link = ocfs2_page_getlink(dentry, &page);
 154         if (IS_ERR(link)) {
 155                 status = PTR_ERR(link);
 156                 mlog_errno(status);
 157                 goto bail;
 158         }
 159
 160         status = vfs_follow_link(nd, link);
 161         if (status && status != -ENOENT)
 162                 mlog_errno(status);
 163 bail:
 164         if (page) {
 165                 kunmap(page);
 166                 page_cache_release(page);
 167         }
 168         if (bh)
 169                 brelse(bh);
 170
 171         return ERR_PTR(status);
 172 }
 173
 174 struct inode_operations ocfs2_symlink_inode_operations = {
 175         .readlink       = page_readlink,
 176         .follow_link    = ocfs2_follow_link,
 177         .getattr        = ocfs2_getattr,
 178 };
 179 struct inode_operations ocfs2_fast_symlink_inode_operations = {
 180         .readlink       = ocfs2_readlink,
 181         .follow_link    = ocfs2_follow_link,
 182         .getattr        = ocfs2_getattr,
 183 };