473 lines
11 KiB
C
473 lines
11 KiB
C
/*
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* linux/fs/minix/dir.c
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*
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* Copyright (C) 1991, 1992 Linus Torvalds
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*
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* minix directory handling functions
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*
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* Updated to filesystem version 3 by Daniel Aragones
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*/
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#include "minix.h"
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#include <linux/buffer_head.h>
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#include <linux/highmem.h>
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#include <linux/swap.h>
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typedef struct minix_dir_entry minix_dirent;
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typedef struct minix3_dir_entry minix3_dirent;
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static int minix_readdir(struct file *, struct dir_context *);
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const struct file_operations minix_dir_operations = {
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.llseek = generic_file_llseek,
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.read = generic_read_dir,
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.iterate = minix_readdir,
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.fsync = generic_file_fsync,
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};
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static inline void dir_put_page(struct page *page)
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{
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kunmap(page);
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page_cache_release(page);
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}
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/*
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* Return the offset into page `page_nr' of the last valid
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* byte in that page, plus one.
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*/
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static unsigned
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minix_last_byte(struct inode *inode, unsigned long page_nr)
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{
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unsigned last_byte = PAGE_CACHE_SIZE;
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if (page_nr == (inode->i_size >> PAGE_CACHE_SHIFT))
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last_byte = inode->i_size & (PAGE_CACHE_SIZE - 1);
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return last_byte;
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}
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static inline unsigned long dir_pages(struct inode *inode)
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{
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return (inode->i_size+PAGE_CACHE_SIZE-1)>>PAGE_CACHE_SHIFT;
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}
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static int dir_commit_chunk(struct page *page, loff_t pos, unsigned len)
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{
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struct address_space *mapping = page->mapping;
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struct inode *dir = mapping->host;
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int err = 0;
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block_write_end(NULL, mapping, pos, len, len, page, NULL);
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if (pos+len > dir->i_size) {
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i_size_write(dir, pos+len);
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mark_inode_dirty(dir);
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}
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if (IS_DIRSYNC(dir))
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err = write_one_page(page, 1);
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else
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unlock_page(page);
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return err;
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}
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static struct page * dir_get_page(struct inode *dir, unsigned long n)
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{
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struct address_space *mapping = dir->i_mapping;
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struct page *page = read_mapping_page(mapping, n, NULL);
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if (!IS_ERR(page))
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kmap(page);
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return page;
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}
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static inline void *minix_next_entry(void *de, struct minix_sb_info *sbi)
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{
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return (void*)((char*)de + sbi->s_dirsize);
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}
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static int minix_readdir(struct file *file, struct dir_context *ctx)
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{
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struct inode *inode = file_inode(file);
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struct super_block *sb = inode->i_sb;
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struct minix_sb_info *sbi = minix_sb(sb);
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unsigned chunk_size = sbi->s_dirsize;
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unsigned long npages = dir_pages(inode);
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unsigned long pos = ctx->pos;
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unsigned offset;
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unsigned long n;
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ctx->pos = pos = ALIGN(pos, chunk_size);
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if (pos >= inode->i_size)
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return 0;
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offset = pos & ~PAGE_CACHE_MASK;
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n = pos >> PAGE_CACHE_SHIFT;
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for ( ; n < npages; n++, offset = 0) {
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char *p, *kaddr, *limit;
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struct page *page = dir_get_page(inode, n);
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if (IS_ERR(page))
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continue;
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kaddr = (char *)page_address(page);
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p = kaddr+offset;
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limit = kaddr + minix_last_byte(inode, n) - chunk_size;
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for ( ; p <= limit; p = minix_next_entry(p, sbi)) {
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const char *name;
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__u32 inumber;
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if (sbi->s_version == MINIX_V3) {
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minix3_dirent *de3 = (minix3_dirent *)p;
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name = de3->name;
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inumber = de3->inode;
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} else {
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minix_dirent *de = (minix_dirent *)p;
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name = de->name;
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inumber = de->inode;
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}
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if (inumber) {
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unsigned l = strnlen(name, sbi->s_namelen);
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if (!dir_emit(ctx, name, l,
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inumber, DT_UNKNOWN)) {
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dir_put_page(page);
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return 0;
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}
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}
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ctx->pos += chunk_size;
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}
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dir_put_page(page);
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}
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return 0;
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}
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static inline int namecompare(int len, int maxlen,
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const char * name, const char * buffer)
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{
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if (len < maxlen && buffer[len])
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return 0;
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return !memcmp(name, buffer, len);
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}
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/*
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* minix_find_entry()
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*
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* finds an entry in the specified directory with the wanted name. It
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* returns the cache buffer in which the entry was found, and the entry
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* itself (as a parameter - res_dir). It does NOT read the inode of the
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* entry - you'll have to do that yourself if you want to.
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*/
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minix_dirent *minix_find_entry(struct dentry *dentry, struct page **res_page)
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{
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const char * name = dentry->d_name.name;
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int namelen = dentry->d_name.len;
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struct inode * dir = dentry->d_parent->d_inode;
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struct super_block * sb = dir->i_sb;
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struct minix_sb_info * sbi = minix_sb(sb);
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unsigned long n;
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unsigned long npages = dir_pages(dir);
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struct page *page = NULL;
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char *p;
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char *namx;
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__u32 inumber;
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*res_page = NULL;
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for (n = 0; n < npages; n++) {
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char *kaddr, *limit;
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page = dir_get_page(dir, n);
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if (IS_ERR(page))
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continue;
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kaddr = (char*)page_address(page);
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limit = kaddr + minix_last_byte(dir, n) - sbi->s_dirsize;
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for (p = kaddr; p <= limit; p = minix_next_entry(p, sbi)) {
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if (sbi->s_version == MINIX_V3) {
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minix3_dirent *de3 = (minix3_dirent *)p;
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namx = de3->name;
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inumber = de3->inode;
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} else {
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minix_dirent *de = (minix_dirent *)p;
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namx = de->name;
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inumber = de->inode;
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}
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if (!inumber)
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continue;
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if (namecompare(namelen, sbi->s_namelen, name, namx))
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goto found;
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}
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dir_put_page(page);
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}
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return NULL;
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found:
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*res_page = page;
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return (minix_dirent *)p;
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}
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int minix_add_link(struct dentry *dentry, struct inode *inode)
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{
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struct inode *dir = dentry->d_parent->d_inode;
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const char * name = dentry->d_name.name;
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int namelen = dentry->d_name.len;
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struct super_block * sb = dir->i_sb;
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struct minix_sb_info * sbi = minix_sb(sb);
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struct page *page = NULL;
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unsigned long npages = dir_pages(dir);
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unsigned long n;
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char *kaddr, *p;
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minix_dirent *de;
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minix3_dirent *de3;
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loff_t pos;
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int err;
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char *namx = NULL;
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__u32 inumber;
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/*
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* We take care of directory expansion in the same loop
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* This code plays outside i_size, so it locks the page
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* to protect that region.
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*/
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for (n = 0; n <= npages; n++) {
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char *limit, *dir_end;
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page = dir_get_page(dir, n);
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err = PTR_ERR(page);
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if (IS_ERR(page))
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goto out;
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lock_page(page);
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kaddr = (char*)page_address(page);
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dir_end = kaddr + minix_last_byte(dir, n);
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limit = kaddr + PAGE_CACHE_SIZE - sbi->s_dirsize;
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for (p = kaddr; p <= limit; p = minix_next_entry(p, sbi)) {
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de = (minix_dirent *)p;
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de3 = (minix3_dirent *)p;
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if (sbi->s_version == MINIX_V3) {
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namx = de3->name;
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inumber = de3->inode;
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} else {
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namx = de->name;
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inumber = de->inode;
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}
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if (p == dir_end) {
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/* We hit i_size */
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if (sbi->s_version == MINIX_V3)
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de3->inode = 0;
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else
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de->inode = 0;
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goto got_it;
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}
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if (!inumber)
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goto got_it;
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err = -EEXIST;
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if (namecompare(namelen, sbi->s_namelen, name, namx))
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goto out_unlock;
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}
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unlock_page(page);
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dir_put_page(page);
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}
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BUG();
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return -EINVAL;
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got_it:
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pos = page_offset(page) + p - (char *)page_address(page);
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err = minix_prepare_chunk(page, pos, sbi->s_dirsize);
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if (err)
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goto out_unlock;
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memcpy (namx, name, namelen);
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if (sbi->s_version == MINIX_V3) {
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memset (namx + namelen, 0, sbi->s_dirsize - namelen - 4);
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de3->inode = inode->i_ino;
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} else {
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memset (namx + namelen, 0, sbi->s_dirsize - namelen - 2);
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de->inode = inode->i_ino;
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}
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err = dir_commit_chunk(page, pos, sbi->s_dirsize);
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dir->i_mtime = dir->i_ctime = CURRENT_TIME_SEC;
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mark_inode_dirty(dir);
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out_put:
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dir_put_page(page);
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out:
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return err;
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out_unlock:
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unlock_page(page);
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goto out_put;
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}
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int minix_delete_entry(struct minix_dir_entry *de, struct page *page)
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{
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struct inode *inode = page->mapping->host;
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char *kaddr = page_address(page);
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loff_t pos = page_offset(page) + (char*)de - kaddr;
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struct minix_sb_info *sbi = minix_sb(inode->i_sb);
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unsigned len = sbi->s_dirsize;
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int err;
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lock_page(page);
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err = minix_prepare_chunk(page, pos, len);
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if (err == 0) {
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if (sbi->s_version == MINIX_V3)
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((minix3_dirent *) de)->inode = 0;
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else
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de->inode = 0;
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err = dir_commit_chunk(page, pos, len);
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} else {
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unlock_page(page);
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}
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dir_put_page(page);
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inode->i_ctime = inode->i_mtime = CURRENT_TIME_SEC;
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mark_inode_dirty(inode);
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return err;
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}
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int minix_make_empty(struct inode *inode, struct inode *dir)
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{
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struct page *page = grab_cache_page(inode->i_mapping, 0);
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struct minix_sb_info *sbi = minix_sb(inode->i_sb);
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char *kaddr;
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int err;
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if (!page)
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return -ENOMEM;
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err = minix_prepare_chunk(page, 0, 2 * sbi->s_dirsize);
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if (err) {
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unlock_page(page);
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goto fail;
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}
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kaddr = kmap_atomic(page);
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memset(kaddr, 0, PAGE_CACHE_SIZE);
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if (sbi->s_version == MINIX_V3) {
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minix3_dirent *de3 = (minix3_dirent *)kaddr;
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de3->inode = inode->i_ino;
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strcpy(de3->name, ".");
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de3 = minix_next_entry(de3, sbi);
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de3->inode = dir->i_ino;
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strcpy(de3->name, "..");
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} else {
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minix_dirent *de = (minix_dirent *)kaddr;
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de->inode = inode->i_ino;
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strcpy(de->name, ".");
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de = minix_next_entry(de, sbi);
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de->inode = dir->i_ino;
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strcpy(de->name, "..");
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}
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kunmap_atomic(kaddr);
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err = dir_commit_chunk(page, 0, 2 * sbi->s_dirsize);
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fail:
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page_cache_release(page);
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return err;
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}
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/*
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* routine to check that the specified directory is empty (for rmdir)
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*/
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int minix_empty_dir(struct inode * inode)
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{
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struct page *page = NULL;
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unsigned long i, npages = dir_pages(inode);
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struct minix_sb_info *sbi = minix_sb(inode->i_sb);
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char *name;
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__u32 inumber;
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for (i = 0; i < npages; i++) {
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char *p, *kaddr, *limit;
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page = dir_get_page(inode, i);
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if (IS_ERR(page))
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continue;
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kaddr = (char *)page_address(page);
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limit = kaddr + minix_last_byte(inode, i) - sbi->s_dirsize;
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for (p = kaddr; p <= limit; p = minix_next_entry(p, sbi)) {
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if (sbi->s_version == MINIX_V3) {
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minix3_dirent *de3 = (minix3_dirent *)p;
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name = de3->name;
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inumber = de3->inode;
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} else {
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minix_dirent *de = (minix_dirent *)p;
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name = de->name;
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inumber = de->inode;
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}
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if (inumber != 0) {
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/* check for . and .. */
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if (name[0] != '.')
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goto not_empty;
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if (!name[1]) {
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if (inumber != inode->i_ino)
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goto not_empty;
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} else if (name[1] != '.')
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goto not_empty;
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else if (name[2])
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goto not_empty;
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}
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}
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dir_put_page(page);
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}
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return 1;
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not_empty:
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dir_put_page(page);
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return 0;
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}
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/* Releases the page */
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void minix_set_link(struct minix_dir_entry *de, struct page *page,
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struct inode *inode)
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{
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struct inode *dir = page->mapping->host;
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struct minix_sb_info *sbi = minix_sb(dir->i_sb);
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loff_t pos = page_offset(page) +
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(char *)de-(char*)page_address(page);
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int err;
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lock_page(page);
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err = minix_prepare_chunk(page, pos, sbi->s_dirsize);
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if (err == 0) {
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if (sbi->s_version == MINIX_V3)
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((minix3_dirent *) de)->inode = inode->i_ino;
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else
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de->inode = inode->i_ino;
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err = dir_commit_chunk(page, pos, sbi->s_dirsize);
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} else {
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unlock_page(page);
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}
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dir_put_page(page);
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dir->i_mtime = dir->i_ctime = CURRENT_TIME_SEC;
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mark_inode_dirty(dir);
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}
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struct minix_dir_entry * minix_dotdot (struct inode *dir, struct page **p)
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{
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struct page *page = dir_get_page(dir, 0);
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struct minix_sb_info *sbi = minix_sb(dir->i_sb);
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struct minix_dir_entry *de = NULL;
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if (!IS_ERR(page)) {
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de = minix_next_entry(page_address(page), sbi);
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*p = page;
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}
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return de;
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}
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ino_t minix_inode_by_name(struct dentry *dentry)
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{
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struct page *page;
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struct minix_dir_entry *de = minix_find_entry(dentry, &page);
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ino_t res = 0;
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if (de) {
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struct address_space *mapping = page->mapping;
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struct inode *inode = mapping->host;
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struct minix_sb_info *sbi = minix_sb(inode->i_sb);
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if (sbi->s_version == MINIX_V3)
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res = ((minix3_dirent *) de)->inode;
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else
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res = de->inode;
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dir_put_page(page);
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}
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return res;
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}
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