xref: /openbmc/linux/fs/affs/dir.c (revision 86878f14)
1  // SPDX-License-Identifier: GPL-2.0
2  /*
3   *  linux/fs/affs/dir.c
4   *
5   *  (c) 1996  Hans-Joachim Widmaier - Rewritten
6   *
7   *  (C) 1993  Ray Burr - Modified for Amiga FFS filesystem.
8   *
9   *  (C) 1992  Eric Youngdale Modified for ISO 9660 filesystem.
10   *
11   *  (C) 1991  Linus Torvalds - minix filesystem
12   *
13   *  affs directory handling functions
14   *
15   */
16  
17  #include <linux/iversion.h>
18  #include "affs.h"
19  
20  static int affs_readdir(struct file *, struct dir_context *);
21  
22  const struct file_operations affs_dir_operations = {
23  	.read		= generic_read_dir,
24  	.llseek		= generic_file_llseek,
25  	.iterate_shared	= affs_readdir,
26  	.fsync		= affs_file_fsync,
27  };
28  
29  /*
30   * directories can handle most operations...
31   */
32  const struct inode_operations affs_dir_inode_operations = {
33  	.create		= affs_create,
34  	.lookup		= affs_lookup,
35  	.link		= affs_link,
36  	.unlink		= affs_unlink,
37  	.symlink	= affs_symlink,
38  	.mkdir		= affs_mkdir,
39  	.rmdir		= affs_rmdir,
40  	.rename		= affs_rename2,
41  	.setattr	= affs_notify_change,
42  };
43  
44  static int
45  affs_readdir(struct file *file, struct dir_context *ctx)
46  {
47  	struct inode		*inode = file_inode(file);
48  	struct super_block	*sb = inode->i_sb;
49  	struct buffer_head	*dir_bh = NULL;
50  	struct buffer_head	*fh_bh = NULL;
51  	unsigned char		*name;
52  	int			 namelen;
53  	u32			 i;
54  	int			 hash_pos;
55  	int			 chain_pos;
56  	u32			 ino;
57  	int			 error = 0;
58  
59  	pr_debug("%s(ino=%lu,f_pos=%llx)\n", __func__, inode->i_ino, ctx->pos);
60  
61  	if (ctx->pos < 2) {
62  		file->private_data = (void *)0;
63  		if (!dir_emit_dots(file, ctx))
64  			return 0;
65  	}
66  
67  	affs_lock_dir(inode);
68  	chain_pos = (ctx->pos - 2) & 0xffff;
69  	hash_pos  = (ctx->pos - 2) >> 16;
70  	if (chain_pos == 0xffff) {
71  		affs_warning(sb, "readdir", "More than 65535 entries in chain");
72  		chain_pos = 0;
73  		hash_pos++;
74  		ctx->pos = ((hash_pos << 16) | chain_pos) + 2;
75  	}
76  	dir_bh = affs_bread(sb, inode->i_ino);
77  	if (!dir_bh)
78  		goto out_unlock_dir;
79  
80  	/* If the directory hasn't changed since the last call to readdir(),
81  	 * we can jump directly to where we left off.
82  	 */
83  	ino = (u32)(long)file->private_data;
84  	if (ino && inode_eq_iversion(inode, file->f_version)) {
85  		pr_debug("readdir() left off=%d\n", ino);
86  		goto inside;
87  	}
88  
89  	ino = be32_to_cpu(AFFS_HEAD(dir_bh)->table[hash_pos]);
90  	for (i = 0; ino && i < chain_pos; i++) {
91  		fh_bh = affs_bread(sb, ino);
92  		if (!fh_bh) {
93  			affs_error(sb, "readdir","Cannot read block %d", i);
94  			error = -EIO;
95  			goto out_brelse_dir;
96  		}
97  		ino = be32_to_cpu(AFFS_TAIL(sb, fh_bh)->hash_chain);
98  		affs_brelse(fh_bh);
99  		fh_bh = NULL;
100  	}
101  	if (ino)
102  		goto inside;
103  	hash_pos++;
104  
105  	for (; hash_pos < AFFS_SB(sb)->s_hashsize; hash_pos++) {
106  		ino = be32_to_cpu(AFFS_HEAD(dir_bh)->table[hash_pos]);
107  		if (!ino)
108  			continue;
109  		ctx->pos = (hash_pos << 16) + 2;
110  inside:
111  		do {
112  			fh_bh = affs_bread(sb, ino);
113  			if (!fh_bh) {
114  				affs_error(sb, "readdir",
115  					   "Cannot read block %d", ino);
116  				break;
117  			}
118  
119  			namelen = min(AFFS_TAIL(sb, fh_bh)->name[0],
120  				      (u8)AFFSNAMEMAX);
121  			name = AFFS_TAIL(sb, fh_bh)->name + 1;
122  			pr_debug("readdir(): dir_emit(\"%.*s\", ino=%u), hash=%d, f_pos=%llx\n",
123  				 namelen, name, ino, hash_pos, ctx->pos);
124  
125  			if (!dir_emit(ctx, name, namelen, ino, DT_UNKNOWN))
126  				goto done;
127  			ctx->pos++;
128  			ino = be32_to_cpu(AFFS_TAIL(sb, fh_bh)->hash_chain);
129  			affs_brelse(fh_bh);
130  			fh_bh = NULL;
131  		} while (ino);
132  	}
133  done:
134  	file->f_version = inode_query_iversion(inode);
135  	file->private_data = (void *)(long)ino;
136  	affs_brelse(fh_bh);
137  
138  out_brelse_dir:
139  	affs_brelse(dir_bh);
140  
141  out_unlock_dir:
142  	affs_unlock_dir(inode);
143  	return error;
144  }
145