lustre/obdfs/symlink.c

   1 /*
   2  *  linux/fs/ext2/symlink.c
   3  *
   4  * Copyright (C) 1992, 1993, 1994, 1995
   5  * Remy Card (card@masi.ibp.fr)
   6  * Laboratoire MASI - Institut Blaise Pascal
   7  * Universite Pierre et Marie Curie (Paris VI)
   8  *
   9  *  from
  10  *
  11  *  linux/fs/minix/symlink.c
  12  *
  13  *  Copyright (C) 1991, 1992  Linus Torvalds
  14  *
  15  *  ext2 symlink handling code
  16  *
  17  * Modified for OBDFS:
  18  *  Copyright (C) 1999 Seagate Technology Inc. (author: braam@stelias.com)
  19  */
  20
  21 #include <asm/uaccess.h>
  22
  23 #include <linux/errno.h>
  24 #include <linux/fs.h>
  25 #include <linux/sched.h>
  26 #include <linux/mm.h>
  27 #include <linux/stat.h>
  28 #include <linux/locks.h>
  29
  30 #include <linux/obd_support.h> /* for ENTRY and EXIT only */
  31 #include <linux/obdfs.h>
  32
  33 /*
  34 static int obdfs_readlink (struct dentry *, char *, int);
  35 static struct dentry *obdfs_follow_link(struct dentry *, struct dentry *, unsigned int);
  36 */
  37
  38 /*
  39  * symlinks can't do much...
  40  */
  41 struct inode_operations obdfs_symlink_inode_operations = {
  42         NULL,                   /* no file-operations */
  43         NULL,                   /* create */
  44         NULL,                   /* lookup */
  45         NULL,                   /* link */
  46         NULL,                   /* unlink */
  47         NULL,                   /* symlink */
  48         NULL,                   /* mkdir */
  49         NULL,                   /* rmdir */
  50         NULL,                   /* mknod */
  51         NULL,                   /* rename */
  52         obdfs_readlink,         /* readlink */
  53         obdfs_follow_link,      /* follow_link */
  54         NULL,                   /* get_block */
  55         NULL,                   /* readpage */
  56         NULL,                   /* writepage */
  57         NULL,                   /* truncate */
  58         NULL,                   /* permission */
  59         NULL                    /* revalidate */
  60 };
  61
  62 /* static */
  63 struct dentry * obdfs_follow_link(struct dentry * dentry,
  64                                          struct dentry *base,
  65                                          unsigned int follow)
  66 {
  67         struct inode *inode = dentry->d_inode;
  68         struct page *page = NULL;
  69         char * link;
  70
  71         ENTRY;
  72         link = (char *) inode->u.ext2_i.i_data;
  73         if (inode->i_blocks) {
  74                 IDEBUG(inode);
  75                 page = obdfs_getpage(inode, 0, 0, 0);
  76                 PDEBUG(page, "follow_link");
  77                 if (!page) {
  78                         dput(base);
  79                         EXIT;
  80                         return ERR_PTR(-EIO);
  81                 }
  82                 link = (char *)page_address(page);
  83         }
  84         UPDATE_ATIME(inode);
  85         base = lookup_dentry(link, base, follow);
  86         if (page) {
  87                 page_cache_release(page);
  88         }
  89         EXIT;
  90         return base;
  91 }
  92
  93 /* static */
  94 int obdfs_readlink (struct dentry * dentry, char * buffer, int buflen)
  95 {
  96         struct inode *inode = dentry->d_inode;
  97         struct page *page = NULL;
  98         char * link;
  99         int i;
 100
 101         ENTRY;
 102         if (buflen > inode->i_sb->s_blocksize - 1)
 103                 buflen = inode->i_sb->s_blocksize - 1;
 104
 105         link = (char *) inode->u.ext2_i.i_data;
 106         if (inode->i_blocks) {
 107                 IDEBUG(inode);
 108                 page = obdfs_getpage(inode, 0, 0, 0);
 109                 PDEBUG(page, "readlink");
 110                 if (!page) {
 111                         EXIT;
 112                         return 0;
 113                 }
 114                 link = (char *)page_address(page);
 115         }
 116
 117         i = 0;
 118         while (i < buflen && link[i])
 119                 i++;
 120         if (copy_to_user(buffer, link, i))
 121                 i = -EFAULT;
 122         if (page) {
 123                 page_cache_release(page);
 124         }
 125         EXIT;
 126         return i;
 127 } /* obdfs_readlink */