| 1 | |
| 2 | |
| 3 | * linux/fs/minix/dir.c
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| 4 | *
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| 5 | * Copyright (C) 1991, 1992 Linus Torvalds
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| 6 | *
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| 7 | * minix directory handling functions
|
| 8 | *
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| 9 | * Updated to filesystem version 3 by Daniel Aragones
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| 10 |
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| 11 |
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| 12 | #include "minix.h"
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| 13 | #include <linux/buffer_head.h>
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| 14 | #include <linux/highmem.h>
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| 15 | #include <linux/swap.h>
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| 16 |
|
| 17 | typedef struct minix_dir_entry minix_dirent;
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| 18 | typedef struct minix3_dir_entry minix3_dirent;
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| 19 |
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| 20 | static int minix_readdir(struct file *, struct dir_context *);
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| 21 |
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| 22 | const struct file_operations minix_dir_operations = {
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| 23 | .llseek = generic_file_llseek,
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| 24 | .read = generic_read_dir,
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| 25 | .iterate_shared = minix_readdir,
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| 26 | .fsync = simple_fsync,
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| 27 | };
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| 28 |
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| 29 | |
| 30 | * Return the offset into page `page_nr' of the last valid
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| 31 | * byte in that page, plus one.
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| 32 |
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| 33 | static unsigned
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| 34 | minix_last_byte(struct inode *inode, unsigned long page_nr)
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| 35 | {
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| 36 | unsigned last_byte = PAGE_SIZE;
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| 37 |
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| 38 | if (page_nr == (inode->i_size >> PAGE_SHIFT))
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| 39 | last_byte = inode->i_size & (PAGE_SIZE - 1);
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| 40 | return last_byte;
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| 41 | }
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| 42 |
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| 43 | static void dir_commit_chunk(struct folio *folio, loff_t pos, unsigned len)
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| 44 | {
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| 45 | struct address_space *mapping = folio->mapping;
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| 46 | struct inode *dir = mapping->host;
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| 47 |
|
| 48 | block_write_end(pos, len, len, folio);
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| 49 |
|
| 50 | if (pos+len > dir->i_size) {
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| 51 | i_size_write(dir, pos+len);
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| 52 | mark_inode_dirty(dir);
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| 53 | }
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| 54 | folio_unlock(folio);
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| 55 | }
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| 56 |
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| 57 | static int minix_handle_dirsync(struct inode *dir)
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| 58 | {
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| 59 | int err;
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| 60 |
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| 61 | err = filemap_write_and_wait(dir->i_mapping);
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| 62 | if (!err)
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| 63 | err = sync_inode_metadata(dir, 1);
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| 64 | return err;
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| 65 | }
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| 66 |
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| 67 | static void *dir_get_folio(struct inode *dir, unsigned long n,
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| 68 | struct folio **foliop)
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| 69 | {
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| 70 | struct folio *folio = read_mapping_folio(dir->i_mapping, n, NULL);
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| 71 |
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| 72 | if (IS_ERR(folio))
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| 73 | return ERR_CAST(folio);
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| 74 | *foliop = folio;
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| 75 | return kmap_local_folio(folio, 0);
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| 76 | }
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| 77 |
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| 78 | static inline void *minix_next_entry(void *de, struct minix_sb_info *sbi)
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| 79 | {
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| 80 | return (void*)((char*)de + sbi->s_dirsize);
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| 81 | }
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| 82 |
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| 83 | static int minix_readdir(struct file *file, struct dir_context *ctx)
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| 84 | {
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| 85 | struct inode *inode = file_inode(file);
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| 86 | struct super_block *sb = inode->i_sb;
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| 87 | struct minix_sb_info *sbi = minix_sb(sb);
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| 88 | unsigned chunk_size = sbi->s_dirsize;
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| 89 | unsigned long npages = dir_pages(inode);
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| 90 | unsigned long pos = ctx->pos;
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| 91 | unsigned offset;
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| 92 | unsigned long n;
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| 93 |
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| 94 | ctx->pos = pos = ALIGN(pos, chunk_size);
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| 95 | if (pos >= inode->i_size)
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| 96 | return 0;
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| 97 |
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| 98 | offset = pos & ~PAGE_MASK;
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| 99 | n = pos >> PAGE_SHIFT;
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| 100 |
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| 101 | for ( ; n < npages; n++, offset = 0) {
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| 102 | char *p, *kaddr, *limit;
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| 103 | struct folio *folio;
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| 104 |
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| 105 | kaddr = dir_get_folio(inode, n, &folio);
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| 106 | if (IS_ERR(kaddr))
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| 107 | continue;
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| 108 | p = kaddr+offset;
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| 109 | limit = kaddr + minix_last_byte(inode, n) - chunk_size;
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| 110 | for ( ; p <= limit; p = minix_next_entry(p, sbi)) {
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| 111 | const char *name;
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| 112 | __u32 inumber;
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| 113 | if (sbi->s_version == MINIX_V3) {
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| 114 | minix3_dirent *de3 = (minix3_dirent *)p;
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| 115 | name = de3->name;
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| 116 | inumber = de3->inode;
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| 117 | } else {
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| 118 | minix_dirent *de = (minix_dirent *)p;
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| 119 | name = de->name;
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| 120 | inumber = de->inode;
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| 121 | }
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| 122 | if (inumber) {
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| 123 | unsigned l = strnlen(name, sbi->s_namelen);
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| 124 | if (!dir_emit(ctx, name, l,
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| 125 | inumber, DT_UNKNOWN)) {
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| 126 | folio_release_kmap(folio, p);
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| 127 | return 0;
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| 128 | }
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| 129 | }
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| 130 | ctx->pos += chunk_size;
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| 131 | }
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| 132 | folio_release_kmap(folio, kaddr);
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| 133 | }
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| 134 | return 0;
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| 135 | }
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| 136 |
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| 137 | static inline int namecompare(int len, int maxlen,
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| 138 | const char * name, const char * buffer)
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| 139 | {
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| 140 | if (len < maxlen && buffer[len])
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| 141 | return 0;
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| 142 | return !memcmp(name, buffer, len);
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| 143 | }
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| 144 |
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| 145 | |
| 146 | * minix_find_entry()
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| 147 | *
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| 148 | * finds an entry in the specified directory with the wanted name.
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| 149 | * It does NOT read the inode of the
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| 150 | * entry - you'll have to do that yourself if you want to.
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| 151 | *
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| 152 | * On Success folio_release_kmap() should be called on *foliop.
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| 153 |
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| 154 | minix_dirent *minix_find_entry(struct dentry *dentry, struct folio **foliop)
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| 155 | {
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| 156 | const char * name = dentry->d_name.name;
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| 157 | int namelen = dentry->d_name.len;
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| 158 | struct inode * dir = d_inode(dentry->d_parent);
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| 159 | struct super_block * sb = dir->i_sb;
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| 160 | struct minix_sb_info * sbi = minix_sb(sb);
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| 161 | unsigned long n;
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| 162 | unsigned long npages = dir_pages(dir);
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| 163 | char *p;
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| 164 |
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| 165 | char *namx;
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| 166 | __u32 inumber;
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| 167 |
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| 168 | for (n = 0; n < npages; n++) {
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| 169 | char *kaddr, *limit;
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| 170 |
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| 171 | kaddr = dir_get_folio(dir, n, foliop);
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| 172 | if (IS_ERR(kaddr))
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| 173 | continue;
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| 174 |
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| 175 | limit = kaddr + minix_last_byte(dir, n) - sbi->s_dirsize;
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| 176 | for (p = kaddr; p <= limit; p = minix_next_entry(p, sbi)) {
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| 177 | if (sbi->s_version == MINIX_V3) {
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| 178 | minix3_dirent *de3 = (minix3_dirent *)p;
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| 179 | namx = de3->name;
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| 180 | inumber = de3->inode;
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| 181 | } else {
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| 182 | minix_dirent *de = (minix_dirent *)p;
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| 183 | namx = de->name;
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| 184 | inumber = de->inode;
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| 185 | }
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| 186 | if (!inumber)
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| 187 | continue;
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| 188 | if (namecompare(namelen, sbi->s_namelen, name, namx))
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| 189 | goto found;
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| 190 | }
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| 191 | folio_release_kmap(*foliop, kaddr);
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| 192 | }
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| 193 | return NULL;
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| 194 |
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| 195 | found:
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| 196 | return (minix_dirent *)p;
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| 197 | }
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| 198 |
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| 199 | int minix_add_link(struct dentry *dentry, struct inode *inode)
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| 200 | {
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| 201 | struct inode *dir = d_inode(dentry->d_parent);
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| 202 | const char * name = dentry->d_name.name;
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| 203 | int namelen = dentry->d_name.len;
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| 204 | struct super_block * sb = dir->i_sb;
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| 205 | struct minix_sb_info * sbi = minix_sb(sb);
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| 206 | struct folio *folio = NULL;
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| 207 | unsigned long npages = dir_pages(dir);
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| 208 | unsigned long n;
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| 209 | char *kaddr, *p;
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| 210 | minix_dirent *de;
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| 211 | minix3_dirent *de3;
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| 212 | loff_t pos;
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| 213 | int err;
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| 214 | char *namx = NULL;
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| 215 | __u32 inumber;
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| 216 |
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| 217 | |
| 218 | * We take care of directory expansion in the same loop
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| 219 | * This code plays outside i_size, so it locks the page
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| 220 | * to protect that region.
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| 221 |
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| 222 | for (n = 0; n <= npages; n++) {
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| 223 | char *limit, *dir_end;
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| 224 |
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| 225 | kaddr = dir_get_folio(dir, n, &folio);
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| 226 | if (IS_ERR(kaddr))
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| 227 | return PTR_ERR(kaddr);
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| 228 | folio_lock(folio);
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| 229 | dir_end = kaddr + minix_last_byte(dir, n);
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| 230 | limit = kaddr + PAGE_SIZE - sbi->s_dirsize;
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| 231 | for (p = kaddr; p <= limit; p = minix_next_entry(p, sbi)) {
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| 232 | de = (minix_dirent *)p;
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| 233 | de3 = (minix3_dirent *)p;
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| 234 | if (sbi->s_version == MINIX_V3) {
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| 235 | namx = de3->name;
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| 236 | inumber = de3->inode;
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| 237 | } else {
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| 238 | namx = de->name;
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| 239 | inumber = de->inode;
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| 240 | }
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| 241 | if (p == dir_end) {
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| 242 |
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| 243 | if (sbi->s_version == MINIX_V3)
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| 244 | de3->inode = 0;
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| 245 | else
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| 246 | de->inode = 0;
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| 247 | goto got_it;
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| 248 | }
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| 249 | if (!inumber)
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| 250 | goto got_it;
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| 251 | err = -EEXIST;
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| 252 | if (namecompare(namelen, sbi->s_namelen, name, namx))
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| 253 | goto out_unlock;
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| 254 | }
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| 255 | folio_unlock(folio);
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| 256 | folio_release_kmap(folio, kaddr);
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| 257 | }
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| 258 | BUG();
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| 259 | return -EINVAL;
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| 260 |
|
| 261 | got_it:
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| 262 | pos = folio_pos(folio) + offset_in_folio(folio, p);
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| 263 | err = minix_prepare_chunk(folio, pos, sbi->s_dirsize);
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| 264 | if (err)
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| 265 | goto out_unlock;
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| 266 | memcpy (namx, name, namelen);
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| 267 | if (sbi->s_version == MINIX_V3) {
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| 268 | memset (namx + namelen, 0, sbi->s_dirsize - namelen - 4);
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| 269 | de3->inode = inode->i_ino;
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| 270 | } else {
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| 271 | memset (namx + namelen, 0, sbi->s_dirsize - namelen - 2);
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| 272 | de->inode = inode->i_ino;
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| 273 | }
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| 274 | dir_commit_chunk(folio, pos, sbi->s_dirsize);
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| 275 | inode_set_mtime_to_ts(dir, inode_set_ctime_current(dir));
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| 276 | mark_inode_dirty(dir);
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| 277 | err = minix_handle_dirsync(dir);
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| 278 | out_put:
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| 279 | folio_release_kmap(folio, kaddr);
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| 280 | return err;
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| 281 | out_unlock:
|
| 282 | folio_unlock(folio);
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| 283 | goto out_put;
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| 284 | }
|
| 285 |
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| 286 | int minix_delete_entry(struct minix_dir_entry *de, struct folio *folio)
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| 287 | {
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| 288 | struct inode *inode = folio->mapping->host;
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| 289 | loff_t pos = folio_pos(folio) + offset_in_folio(folio, de);
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| 290 | struct minix_sb_info *sbi = minix_sb(inode->i_sb);
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| 291 | unsigned len = sbi->s_dirsize;
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| 292 | int err;
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| 293 |
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| 294 | folio_lock(folio);
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| 295 | err = minix_prepare_chunk(folio, pos, len);
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| 296 | if (err) {
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| 297 | folio_unlock(folio);
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| 298 | return err;
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| 299 | }
|
| 300 | if (sbi->s_version == MINIX_V3)
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| 301 | ((minix3_dirent *)de)->inode = 0;
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| 302 | else
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| 303 | de->inode = 0;
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| 304 | dir_commit_chunk(folio, pos, len);
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| 305 | inode_set_mtime_to_ts(inode, inode_set_ctime_current(inode));
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| 306 | mark_inode_dirty(inode);
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| 307 | return minix_handle_dirsync(inode);
|
| 308 | }
|
| 309 |
|
| 310 | int minix_make_empty(struct inode *inode, struct inode *dir)
|
| 311 | {
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| 312 | struct folio *folio = filemap_grab_folio(inode->i_mapping, 0);
|
| 313 | struct minix_sb_info *sbi = minix_sb(inode->i_sb);
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| 314 | char *kaddr;
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| 315 | int err;
|
| 316 |
|
| 317 | if (IS_ERR(folio))
|
| 318 | return PTR_ERR(folio);
|
| 319 | err = minix_prepare_chunk(folio, 0, 2 * sbi->s_dirsize);
|
| 320 | if (err) {
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| 321 | folio_unlock(folio);
|
| 322 | goto fail;
|
| 323 | }
|
| 324 |
|
| 325 | kaddr = kmap_local_folio(folio, 0);
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| 326 | memset(kaddr, 0, folio_size(folio));
|
| 327 |
|
| 328 | if (sbi->s_version == MINIX_V3) {
|
| 329 | minix3_dirent *de3 = (minix3_dirent *)kaddr;
|
| 330 |
|
| 331 | de3->inode = inode->i_ino;
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| 332 | strcpy(de3->name, ".");
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| 333 | de3 = minix_next_entry(de3, sbi);
|
| 334 | de3->inode = dir->i_ino;
|
| 335 | strcpy(de3->name, "..");
|
| 336 | } else {
|
| 337 | minix_dirent *de = (minix_dirent *)kaddr;
|
| 338 |
|
| 339 | de->inode = inode->i_ino;
|
| 340 | strcpy(de->name, ".");
|
| 341 | de = minix_next_entry(de, sbi);
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| 342 | de->inode = dir->i_ino;
|
| 343 | strcpy(de->name, "..");
|
| 344 | }
|
| 345 | kunmap_local(kaddr);
|
| 346 |
|
| 347 | dir_commit_chunk(folio, 0, 2 * sbi->s_dirsize);
|
| 348 | err = minix_handle_dirsync(inode);
|
| 349 | fail:
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| 350 | folio_put(folio);
|
| 351 | return err;
|
| 352 | }
|
| 353 |
|
| 354 | |
| 355 | * routine to check that the specified directory is empty (for rmdir)
|
| 356 |
|
| 357 | int minix_empty_dir(struct inode * inode)
|
| 358 | {
|
| 359 | struct folio *folio = NULL;
|
| 360 | unsigned long i, npages = dir_pages(inode);
|
| 361 | struct minix_sb_info *sbi = minix_sb(inode->i_sb);
|
| 362 | char *name, *kaddr;
|
| 363 | __u32 inumber;
|
| 364 |
|
| 365 | for (i = 0; i < npages; i++) {
|
| 366 | char *p, *limit;
|
| 367 |
|
| 368 | kaddr = dir_get_folio(inode, i, &folio);
|
| 369 | if (IS_ERR(kaddr))
|
| 370 | continue;
|
| 371 |
|
| 372 | limit = kaddr + minix_last_byte(inode, i) - sbi->s_dirsize;
|
| 373 | for (p = kaddr; p <= limit; p = minix_next_entry(p, sbi)) {
|
| 374 | if (sbi->s_version == MINIX_V3) {
|
| 375 | minix3_dirent *de3 = (minix3_dirent *)p;
|
| 376 | name = de3->name;
|
| 377 | inumber = de3->inode;
|
| 378 | } else {
|
| 379 | minix_dirent *de = (minix_dirent *)p;
|
| 380 | name = de->name;
|
| 381 | inumber = de->inode;
|
| 382 | }
|
| 383 |
|
| 384 | if (inumber != 0) {
|
| 385 |
|
| 386 | if (name[0] != '.')
|
| 387 | goto not_empty;
|
| 388 | if (!name[1]) {
|
| 389 | if (inumber != inode->i_ino)
|
| 390 | goto not_empty;
|
| 391 | } else if (name[1] != '.')
|
| 392 | goto not_empty;
|
| 393 | else if (name[2])
|
| 394 | goto not_empty;
|
| 395 | }
|
| 396 | }
|
| 397 | folio_release_kmap(folio, kaddr);
|
| 398 | }
|
| 399 | return 1;
|
| 400 |
|
| 401 | not_empty:
|
| 402 | folio_release_kmap(folio, kaddr);
|
| 403 | return 0;
|
| 404 | }
|
| 405 |
|
| 406 |
|
| 407 | int minix_set_link(struct minix_dir_entry *de, struct folio *folio,
|
| 408 | struct inode *inode)
|
| 409 | {
|
| 410 | struct inode *dir = folio->mapping->host;
|
| 411 | struct minix_sb_info *sbi = minix_sb(dir->i_sb);
|
| 412 | loff_t pos = folio_pos(folio) + offset_in_folio(folio, de);
|
| 413 | int err;
|
| 414 |
|
| 415 | folio_lock(folio);
|
| 416 | err = minix_prepare_chunk(folio, pos, sbi->s_dirsize);
|
| 417 | if (err) {
|
| 418 | folio_unlock(folio);
|
| 419 | return err;
|
| 420 | }
|
| 421 | if (sbi->s_version == MINIX_V3)
|
| 422 | ((minix3_dirent *)de)->inode = inode->i_ino;
|
| 423 | else
|
| 424 | de->inode = inode->i_ino;
|
| 425 | dir_commit_chunk(folio, pos, sbi->s_dirsize);
|
| 426 | inode_set_mtime_to_ts(dir, inode_set_ctime_current(dir));
|
| 427 | mark_inode_dirty(dir);
|
| 428 | return minix_handle_dirsync(dir);
|
| 429 | }
|
| 430 |
|
| 431 | struct minix_dir_entry *minix_dotdot(struct inode *dir, struct folio **foliop)
|
| 432 | {
|
| 433 | struct minix_sb_info *sbi = minix_sb(dir->i_sb);
|
| 434 | struct minix_dir_entry *de = dir_get_folio(dir, 0, foliop);
|
| 435 |
|
| 436 | if (!IS_ERR(de))
|
| 437 | return minix_next_entry(de, sbi);
|
| 438 | return NULL;
|
| 439 | }
|
| 440 |
|
| 441 | ino_t minix_inode_by_name(struct dentry *dentry)
|
| 442 | {
|
| 443 | struct folio *folio;
|
| 444 | struct minix_dir_entry *de = minix_find_entry(dentry, &folio);
|
| 445 | ino_t res = 0;
|
| 446 |
|
| 447 | if (de) {
|
| 448 | struct inode *inode = folio->mapping->host;
|
| 449 | struct minix_sb_info *sbi = minix_sb(inode->i_sb);
|
| 450 |
|
| 451 | if (sbi->s_version == MINIX_V3)
|
| 452 | res = ((minix3_dirent *) de)->inode;
|
| 453 | else
|
| 454 | res = de->inode;
|
| 455 | folio_release_kmap(folio, de);
|
| 456 | }
|
| 457 | return res;
|
| 458 | }
|