GNU Linux-libre 4.19.211-gnu1
[releases.git] / fs / affs / dir.c
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 }