fs/nfs/symlink.c

   1 /*
   2  *  linux/fs/nfs/symlink.c
   3  *
   4  *  Copyright (C) 1992  Rick Sladkey
   5  *
   6  *  Optimization changes Copyright (C) 1994 Florian La Roche
   7  *
   8  *  Jun 7 1999, cache symlink lookups in the page cache.  -DaveM
   9  *
  10  *  nfs symlink handling code
  11  */
  12
  13 #define NFS_NEED_XDR_TYPES
  14 #include <linux/time.h>
  15 #include <linux/errno.h>
  16 #include <linux/sunrpc/clnt.h>
  17 #include <linux/nfs.h>
  18 #include <linux/nfs2.h>
  19 #include <linux/nfs_fs.h>
  20 #include <linux/pagemap.h>
  21 #include <linux/stat.h>
  22 #include <linux/mm.h>
  23 #include <linux/slab.h>
  24 #include <linux/string.h>
  25 #include <linux/namei.h>
  26
  27 /* Symlink caching in the page cache is even more simplistic
  28  * and straight-forward than readdir caching.
  29  */
  30
  31 static int nfs_symlink_filler(struct inode *inode, struct page *page)
  32 {
  33         int error;
  34
  35         error = NFS_PROTO(inode)->readlink(inode, page, 0, PAGE_SIZE);
  36         if (error < 0)
  37                 goto error;
  38         SetPageUptodate(page);
  39         unlock_page(page);
  40         return 0;
  41
  42 error:
  43         SetPageError(page);
  44         unlock_page(page);
  45         return -EIO;
  46 }
  47
  48 static void *nfs_follow_link(struct dentry *dentry, struct nameidata *nd)
  49 {
  50         struct inode *inode = dentry->d_inode;
  51         struct page *page;
  52         void *err;
  53
  54         err = ERR_PTR(nfs_revalidate_mapping_nolock(inode, inode->i_mapping));
  55         if (err)
  56                 goto read_failed;
  57         page = read_cache_page(&inode->i_data, 0,
  58                                 (filler_t *)nfs_symlink_filler, inode);
  59         if (IS_ERR(page)) {
  60                 err = page;
  61                 goto read_failed;
  62         }
  63         nd_set_link(nd, kmap(page));
  64         return page;
  65
  66 read_failed:
  67         nd_set_link(nd, err);
  68         return NULL;
  69 }
  70
  71 /*
  72  * symlinks can't do much...
  73  */
  74 const struct inode_operations nfs_symlink_inode_operations = {
  75         .readlink       = generic_readlink,
  76         .follow_link    = nfs_follow_link,
  77         .put_link       = page_put_link,
  78         .getattr        = nfs_getattr,
  79         .setattr        = nfs_setattr,
  80 };