xref: /openbmc/linux/fs/efs/symlink.c (revision 2d8867f3)
1  // SPDX-License-Identifier: GPL-2.0
2  /*
3   * symlink.c
4   *
5   * Copyright (c) 1999 Al Smith
6   *
7   * Portions derived from work (c) 1995,1996 Christian Vogelgsang.
8   */
9  
10  #include <linux/string.h>
11  #include <linux/pagemap.h>
12  #include <linux/buffer_head.h>
13  #include "efs.h"
14  
15  static int efs_symlink_read_folio(struct file *file, struct folio *folio)
16  {
17  	struct page *page = &folio->page;
18  	char *link = page_address(page);
19  	struct buffer_head * bh;
20  	struct inode * inode = page->mapping->host;
21  	efs_block_t size = inode->i_size;
22  	int err;
23  
24  	err = -ENAMETOOLONG;
25  	if (size > 2 * EFS_BLOCKSIZE)
26  		goto fail;
27  
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  	SetPageUptodate(page);
44  	unlock_page(page);
45  	return 0;
46  fail:
47  	SetPageError(page);
48  	unlock_page(page);
49  	return err;
50  }
51  
52  const struct address_space_operations efs_symlink_aops = {
53  	.read_folio	= efs_symlink_read_folio
54  };
55