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 static struct dentry * obdfs_follow_link(struct dentry * dentry,
  34                                          struct dentry *base,
  35                                          unsigned int follow)
  36 {
  37         struct inode *inode = dentry->d_inode;
  38         struct page *page = NULL;
  39         char * link;
  40
  41         ENTRY;
  42         link = obdfs_i2info(inode)->oi_inline;
  43         if (!obdfs_has_inline(inode)) {
  44                 OIDEBUG(inode);
  45                 page = obdfs_getpage(inode, 0, 0, 0);
  46                 PDEBUG(page, "follow_link");
  47                 if (!page) {
  48                         dput(base);
  49                         EXIT;
  50                         return ERR_PTR(-EIO);
  51                 }
  52                 link = (char *)page_address(page);
  53         }
  54         UPDATE_ATIME(inode);
  55         base = lookup_dentry(link, base, follow);
  56         if (page) {
  57                 page_cache_release(page);
  58         }
  59         EXIT;
  60         return base;
  61 }
  62
  63 static int obdfs_readlink (struct dentry * dentry, char * buffer, int buflen)
  64 {
  65         struct inode *inode = dentry->d_inode;
  66         struct page *page = NULL;
  67         char * link;
  68         int i;
  69
  70         ENTRY;
  71         if (buflen > inode->i_sb->s_blocksize - 1)
  72                 buflen = inode->i_sb->s_blocksize - 1;
  73
  74         link = obdfs_i2info(inode)->oi_inline;
  75         if (!obdfs_has_inline(inode)) {
  76                 OIDEBUG(inode);
  77                 page = obdfs_getpage(inode, 0, 0, 0);
  78                 PDEBUG(page, "readlink");
  79                 if (!page) {
  80                         EXIT;
  81                         return 0;
  82                 }
  83                 link = (char *)page_address(page);
  84         }
  85
  86         i = 0;
  87         while (i < buflen && link[i])
  88                 i++;
  89         if (copy_to_user(buffer, link, i))
  90                 i = -EFAULT;
  91         if (page) {
  92                 page_cache_release(page);
  93         }
  94         EXIT;
  95         return i;
  96 } /* obdfs_readlink */
  97
  98 /*
  99  * symlinks can't do much...
 100  */
 101 struct inode_operations obdfs_symlink_inode_operations = {
 102         NULL,                   /* no file-operations */
 103         NULL,                   /* create */
 104         NULL,                   /* lookup */
 105         NULL,                   /* link */
 106         NULL,                   /* unlink */
 107         NULL,                   /* symlink */
 108         NULL,                   /* mkdir */
 109         NULL,                   /* rmdir */
 110         NULL,                   /* mknod */
 111         NULL,                   /* rename */
 112         obdfs_readlink,         /* readlink */
 113         obdfs_follow_link,      /* follow_link */
 114         NULL,                   /* get_block */
 115         NULL,                   /* readpage */
 116         NULL,                   /* writepage */
 117         NULL,                   /* truncate */
 118         NULL,                   /* permission */
 119         NULL                    /* revalidate */
 120 };
 121