Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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kernel
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linux
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 /* the last dirent in the block? */
23 if (de + 1 >= end)
24 de_namelen = strnlen(de_name, maxsize - nameoff);
25 else
26 de_namelen = le16_to_cpu(de[1].nameoff) - nameoff;
27
28 /* a corrupted entry is found */
29 if (nameoff + de_namelen > maxsize ||
30 de_namelen > EROFS_NAME_LEN) {
31 erofs_err(dir->i_sb, "bogus dirent @ nid %llu",
32 EROFS_I(dir)->nid);
33 DBG_BUGON(1);
34 return -EFSCORRUPTED;
35 }
36
37 if (!dir_emit(ctx, de_name, de_namelen,
38 erofs_nid_to_ino64(EROFS_SB(dir->i_sb),
39 le64_to_cpu(de->nid)), d_type))
40 return 1;
41 ++de;
42 ctx->pos += sizeof(struct erofs_dirent);
43 }
44 return 0;
45}
46
47static int erofs_readdir(struct file *f, struct dir_context *ctx)
48{
49 struct inode *dir = file_inode(f);
50 struct erofs_buf buf = __EROFS_BUF_INITIALIZER;
51 struct super_block *sb = dir->i_sb;
52 struct file_ra_state *ra = &f->f_ra;
53 unsigned long bsz = sb->s_blocksize;
54 unsigned int ofs = erofs_blkoff(sb, ctx->pos);
55 pgoff_t ra_pages = DIV_ROUND_UP_POW2(
56 EROFS_I_SB(dir)->dir_ra_bytes, PAGE_SIZE);
57 pgoff_t nr_pages = DIV_ROUND_UP_POW2(dir->i_size, PAGE_SIZE);
58 int err = 0;
59 bool initial = true;
60
61 buf.mapping = dir->i_mapping;
62 while (ctx->pos < dir->i_size) {
63 erofs_off_t dbstart = ctx->pos - ofs;
64 struct erofs_dirent *de;
65 unsigned int nameoff, maxsize;
66
67 if (fatal_signal_pending(current)) {
68 err = -ERESTARTSYS;
69 break;
70 }
71
72 /* readahead blocks to enhance performance for large directories */
73 if (ra_pages) {
74 pgoff_t idx = DIV_ROUND_UP_POW2(ctx->pos, PAGE_SIZE);
75 pgoff_t pages = min(nr_pages - idx, ra_pages);
76
77 if (pages > 1 && !ra_has_index(ra, idx))
78 page_cache_sync_readahead(dir->i_mapping, ra,
79 f, idx, pages);
80 }
81
82 de = erofs_bread(&buf, dbstart, true);
83 if (IS_ERR(de)) {
84 erofs_err(sb, "failed to readdir of logical block %llu of nid %llu",
85 erofs_blknr(sb, dbstart), EROFS_I(dir)->nid);
86 err = PTR_ERR(de);
87 break;
88 }
89
90 nameoff = le16_to_cpu(de->nameoff);
91 if (nameoff < sizeof(struct erofs_dirent) || nameoff >= bsz) {
92 erofs_err(sb, "invalid de[0].nameoff %u @ nid %llu",
93 nameoff, EROFS_I(dir)->nid);
94 err = -EFSCORRUPTED;
95 break;
96 }
97
98 maxsize = min_t(unsigned int, dir->i_size - dbstart, bsz);
99 /* search dirents at the arbitrary position */
100 if (initial) {
101 initial = false;
102 ofs = roundup(ofs, sizeof(struct erofs_dirent));
103 ctx->pos = dbstart + ofs;
104 }
105
106 err = erofs_fill_dentries(dir, ctx, de, (void *)de + ofs,
107 nameoff, maxsize);
108 if (err)
109 break;
110 ctx->pos = dbstart + maxsize;
111 ofs = 0;
112 cond_resched();
113 }
114 erofs_put_metabuf(&buf);
115 if (EROFS_I(dir)->dot_omitted && ctx->pos == dir->i_size) {
116 if (!dir_emit_dot(f, ctx))
117 return 0;
118 ++ctx->pos;
119 }
120 return err < 0 ? err : 0;
121}
122
123const struct file_operations erofs_dir_fops = {
124 .llseek = generic_file_llseek,
125 .read = generic_read_dir,
126 .iterate_shared = erofs_readdir,
127 .unlocked_ioctl = erofs_ioctl,
128#ifdef CONFIG_COMPAT
129 .compat_ioctl = erofs_compat_ioctl,
130#endif
131 .setlease = generic_setlease,
132};