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 #include <linux/time.h>
  14 #include <linux/errno.h>
  15 #include <linux/sunrpc/clnt.h>
  16 #include <linux/nfs.h>
  17 #include <linux/nfs2.h>
  18 #include <linux/nfs_fs.h>
  19 #include <linux/pagemap.h>
  20 #include <linux/stat.h>
  21 #include <linux/mm.h>
  22 #include <linux/string.h>
  23
  24 /* Symlink caching in the page cache is even more simplistic
  25  * and straight-forward than readdir caching.
  26  */
  27
  28 static int nfs_symlink_filler(struct inode *inode, struct page *page)
  29 {
  30         int error;
  31
  32         error = NFS_PROTO(inode)->readlink(inode, page, 0, PAGE_SIZE);
  33         if (error < 0)
  34                 goto error;
  35         SetPageUptodate(page);
  36         unlock_page(page);
  37         return 0;
  38
  39 error:
  40         SetPageError(page);
  41         unlock_page(page);
  42         return -EIO;
  43 }
  44
  45 static const char *nfs_get_link(struct dentry *dentry,
  46                                 struct inode *inode, void **cookie)
  47 {
  48         struct page *page;
  49         void *err;
  50
  51         if (!dentry)
  52                 return ERR_PTR(-ECHILD);
  53
  54         err = ERR_PTR(nfs_revalidate_mapping(inode, inode->i_mapping));
  55         if (err)
  56                 return err;
  57         page = read_cache_page(&inode->i_data, 0,
  58                                 (filler_t *)nfs_symlink_filler, inode);
  59         if (IS_ERR(page))
  60                 return ERR_CAST(page);
  61         *cookie = page;
  62         return page_address(page);
  63 }
  64
  65 /*
  66  * symlinks can't do much...
  67  */
  68 const struct inode_operations nfs_symlink_inode_operations = {
  69         .readlink       = generic_readlink,
  70         .get_link       = nfs_get_link,
  71         .put_link       = page_put_link,
  72         .getattr        = nfs_getattr,
  73         .setattr        = nfs_setattr,
  74 };