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
affs_readdir(struct file * file,struct dir_context * ctx)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