projects/linux·blob master · refs

134 lines · 3.7 KiB

1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Copyright (C) 2017-2018 HUAWEI, Inc.
4 * https://www.huawei.com/
5 * Copyright (C) 2022, Alibaba Cloud
6 */
7#include "internal.h"
8#include <linux/filelock.h>
9
10static int erofs_fill_dentries(struct inode *dir, struct dir_context *ctx,
11 void *dentry_blk, struct erofs_dirent *de,
12 unsigned int nameoff0, unsigned int maxsize)
13{
14 const struct erofs_dirent *end = dentry_blk + nameoff0;
15
16 while (de < end) {
17 unsigned char d_type = fs_ftype_to_dtype(de->file_type);
18 unsigned int nameoff = le16_to_cpu(de->nameoff);
19 const char *de_name = (char *)dentry_blk + nameoff;
20 unsigned int de_namelen;
21
22 /* non-trailing dirent in the directory block? */
23 if (de + 1 < end)
24 de_namelen = le16_to_cpu(de[1].nameoff) - nameoff;
25 else if (maxsize <= nameoff)
26 goto err_bogus;
27 else
28 de_namelen = strnlen(de_name, maxsize - nameoff);
29
30 /* a corrupted entry is found (including negative namelen) */
31 if (!in_range32(de_namelen, 1, EROFS_NAME_LEN) ||
32 nameoff + de_namelen > maxsize)
33 goto err_bogus;
34
35 if (!dir_emit(ctx, de_name, de_namelen,
36 erofs_nid_to_ino64(EROFS_SB(dir->i_sb),
37 le64_to_cpu(de->nid)), d_type))
38 return 1;
39 ++de;
40 ctx->pos += sizeof(struct erofs_dirent);
41 }
42 return 0;
43err_bogus:
44 erofs_err(dir->i_sb, "bogus dirent @ nid %llu", EROFS_I(dir)->nid);
45 DBG_BUGON(1);
46 return -EFSCORRUPTED;
47}
48
49static int erofs_readdir(struct file *f, struct dir_context *ctx)
50{
51 struct inode *dir = file_inode(f);
52 struct erofs_buf buf = __EROFS_BUF_INITIALIZER;
53 struct super_block *sb = dir->i_sb;
54 struct file_ra_state *ra = &f->f_ra;
55 unsigned long bsz = sb->s_blocksize;
56 unsigned int ofs = erofs_blkoff(sb, ctx->pos);
57 pgoff_t ra_pages = DIV_ROUND_UP_POW2(
58 EROFS_I_SB(dir)->dir_ra_bytes, PAGE_SIZE);
59 pgoff_t nr_pages = DIV_ROUND_UP_POW2(dir->i_size, PAGE_SIZE);
60 int err = 0;
61 bool initial = true;
62
63 buf.mapping = dir->i_mapping;
64 while (ctx->pos < dir->i_size) {
65 erofs_off_t dbstart = ctx->pos - ofs;
66 struct erofs_dirent *de;
67 unsigned int nameoff, maxsize;
68
69 if (fatal_signal_pending(current)) {
70 err = -ERESTARTSYS;
71 break;
72 }
73
74 /* readahead blocks to enhance performance for large directories */
75 if (ra_pages) {
76 pgoff_t idx = DIV_ROUND_UP_POW2(ctx->pos, PAGE_SIZE);
77 pgoff_t pages = min(nr_pages - idx, ra_pages);
78
79 if (pages > 1 && !ra_has_index(ra, idx))
80 page_cache_sync_readahead(dir->i_mapping, ra,
81 f, idx, pages);
82 }
83
84 de = erofs_bread(&buf, dbstart, true);
85 if (IS_ERR(de)) {
86 erofs_err(sb, "failed to readdir of logical block %llu of nid %llu",
87 erofs_blknr(sb, dbstart), EROFS_I(dir)->nid);
88 err = PTR_ERR(de);
89 break;
90 }
91
92 nameoff = le16_to_cpu(de->nameoff);
93 if (!nameoff || nameoff >= bsz || (nameoff % sizeof(*de))) {
94 erofs_err(sb, "invalid de[0].nameoff %u @ nid %llu",
95 nameoff, EROFS_I(dir)->nid);
96 err = -EFSCORRUPTED;
97 break;
98 }
99
100 maxsize = min_t(unsigned int, dir->i_size - dbstart, bsz);
101 /* search dirents at the arbitrary position */
102 if (initial) {
103 initial = false;
104 ofs = roundup(ofs, sizeof(struct erofs_dirent));
105 ctx->pos = dbstart + ofs;
106 }
107
108 err = erofs_fill_dentries(dir, ctx, de, (void *)de + ofs,
109 nameoff, maxsize);
110 if (err)
111 break;
112 ctx->pos = dbstart + maxsize;
113 ofs = 0;
114 cond_resched();
115 }
116 erofs_put_metabuf(&buf);
117 if (EROFS_I(dir)->dot_omitted && ctx->pos == dir->i_size) {
118 if (!dir_emit_dot(f, ctx))
119 return 0;
120 ++ctx->pos;
121 }
122 return err < 0 ? err : 0;
123}
124
125const struct file_operations erofs_dir_fops = {
126 .llseek = generic_file_llseek,
127 .read = generic_read_dir,
128 .iterate_shared = erofs_readdir,
129 .unlocked_ioctl = erofs_ioctl,
130#ifdef CONFIG_COMPAT
131 .compat_ioctl = erofs_compat_ioctl,
132#endif
133 .setlease = generic_setlease,
134};