fs/efs/symlink.c

   1 /*
   2  * symlink.c
   3  *
   4  * Copyright (c) 1999 Al Smith
   5  *
   6  * Portions derived from work (c) 1995,1996 Christian Vogelgsang.
   7  */
   8
   9 #include <linux/string.h>
  10 #include <linux/pagemap.h>
  11 #include <linux/buffer_head.h>
  12 #include <linux/smp_lock.h>
  13 #include "efs.h"
  14
  15 static int efs_symlink_readpage(struct file *file, struct page *page)
  16 {
  17         char *link = kmap(page);
  18         struct buffer_head * bh;
  19         struct inode * inode = page->mapping->host;
  20         efs_block_t size = inode->i_size;
  21         int err;
  22
  23         err = -ENAMETOOLONG;
  24         if (size > 2 * EFS_BLOCKSIZE)
  25                 goto fail_notlocked;
  26
  27         lock_kernel();
  28         /* read first 512 bytes of link target */
  29         err = -EIO;
  30         bh = sb_bread(inode->i_sb, efs_bmap(inode, 0));
  31         if (!bh)
  32                 goto fail;
  33         memcpy(link, bh->b_data, (size > EFS_BLOCKSIZE) ? EFS_BLOCKSIZE : size);
  34         brelse(bh);
  35         if (size > EFS_BLOCKSIZE) {
  36                 bh = sb_bread(inode->i_sb, efs_bmap(inode, 1));
  37                 if (!bh)
  38                         goto fail;
  39                 memcpy(link + EFS_BLOCKSIZE, bh->b_data, size - EFS_BLOCKSIZE);
  40                 brelse(bh);
  41         }
  42         link[size] = '\0';
  43         unlock_kernel();
  44         SetPageUptodate(page);
  45         kunmap(page);
  46         unlock_page(page);
  47         return 0;
  48 fail:
  49         unlock_kernel();
  50 fail_notlocked:
  51         SetPageError(page);
  52         kunmap(page);
  53         unlock_page(page);
  54         return err;
  55 }
  56
  57 const struct address_space_operations efs_symlink_aops = {
  58         .readpage       = efs_symlink_readpage
  59 };