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