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
20static int affs_readdir(struct file *, struct dir_context *);
21
22const 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 */
32const 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
44static int
45affs_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;
110inside:
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	}
133done:
134	file->f_version = inode_query_iversion(inode);
135	file->private_data = (void *)(long)ino;
136	affs_brelse(fh_bh);
137
138out_brelse_dir:
139	affs_brelse(dir_bh);
140
141out_unlock_dir:
142	affs_unlock_dir(inode);
143	return error;
144}
145