Orange Pi5 kernel

// SPDX-License-Identifier: GPL-2.0
/*
 *  linux/fs/minix/dir.c
 *
 *  Copyright (C) 1991, 1992 Linus Torvalds
 *
 *  minix directory handling functions
 *
 *  Updated to filesystem version 3 by Daniel Aragones
 */
 
#include "minix.h"
#include <linux/buffer_head.h>
#include <linux/highmem.h>
#include <linux/swap.h>
 
typedef struct minix_dir_entry minix_dirent;
typedef struct minix3_dir_entry minix3_dirent;
 
static int minix_readdir(struct file *, struct dir_context *);
 
const struct file_operations minix_dir_operations = {
<------>.llseek		= generic_file_llseek,
<------>.read		= generic_read_dir,
<------>.iterate_shared	= minix_readdir,
<------>.fsync		= generic_file_fsync,
};
 
static inline void dir_put_page(struct page *page)
{
<------>kunmap(page);
<------>put_page(page);
}
 
/*
 * Return the offset into page `page_nr' of the last valid
 * byte in that page, plus one.
 */
static unsigned
minix_last_byte(struct inode *inode, unsigned long page_nr)
{
<------>unsigned last_byte = PAGE_SIZE;
 
<------>if (page_nr == (inode->i_size >> PAGE_SHIFT))
<------><------>last_byte = inode->i_size & (PAGE_SIZE - 1);
<------>return last_byte;
}
 
static int dir_commit_chunk(struct page *page, loff_t pos, unsigned len)
{
<------>struct address_space *mapping = page->mapping;
<------>struct inode *dir = mapping->host;
<------>int err = 0;
<------>block_write_end(NULL, mapping, pos, len, len, page, NULL);
 
<------>if (pos+len > dir->i_size) {
<------><------>i_size_write(dir, pos+len);
<------><------>mark_inode_dirty(dir);
<------>}
<------>if (IS_DIRSYNC(dir))
<------><------>err = write_one_page(page);
<------>else
<------><------>unlock_page(page);
<------>return err;
}
 
static struct page * dir_get_page(struct inode *dir, unsigned long n)
{
<------>struct address_space *mapping = dir->i_mapping;
<------>struct page *page = read_mapping_page(mapping, n, NULL);
<------>if (!IS_ERR(page))
<------><------>kmap(page);
<------>return page;
}
 
static inline void *minix_next_entry(void *de, struct minix_sb_info *sbi)
{
<------>return (void*)((char*)de + sbi->s_dirsize);
}
 
static int minix_readdir(struct file *file, struct dir_context *ctx)
{
<------>struct inode *inode = file_inode(file);
<------>struct super_block *sb = inode->i_sb;
<------>struct minix_sb_info *sbi = minix_sb(sb);
<------>unsigned chunk_size = sbi->s_dirsize;
<------>unsigned long npages = dir_pages(inode);
<------>unsigned long pos = ctx->pos;
<------>unsigned offset;
<------>unsigned long n;
 
<------>ctx->pos = pos = ALIGN(pos, chunk_size);
<------>if (pos >= inode->i_size)
<------><------>return 0;
 
<------>offset = pos & ~PAGE_MASK;
<------>n = pos >> PAGE_SHIFT;
 
<------>for ( ; n < npages; n++, offset = 0) {
<------><------>char *p, *kaddr, *limit;
<------><------>struct page *page = dir_get_page(inode, n);
 
<------><------>if (IS_ERR(page))
<------><------><------>continue;
<------><------>kaddr = (char *)page_address(page);
<------><------>p = kaddr+offset;
<------><------>limit = kaddr + minix_last_byte(inode, n) - chunk_size;
<------><------>for ( ; p <= limit; p = minix_next_entry(p, sbi)) {
<------><------><------>const char *name;
<------><------><------>__u32 inumber;
<------><------><------>if (sbi->s_version == MINIX_V3) {
<------><------><------><------>minix3_dirent *de3 = (minix3_dirent *)p;
<------><------><------><------>name = de3->name;
<------><------><------><------>inumber = de3->inode;
<------> 		} else {
<------><------><------><------>minix_dirent *de = (minix_dirent *)p;
<------><------><------><------>name = de->name;
<------><------><------><------>inumber = de->inode;
<------><------><------>}
<------><------><------>if (inumber) {
<------><------><------><------>unsigned l = strnlen(name, sbi->s_namelen);
<------><------><------><------>if (!dir_emit(ctx, name, l,
<------><------><------><------><------>      inumber, DT_UNKNOWN)) {
<------><------><------><------><------>dir_put_page(page);
<------><------><------><------><------>return 0;
<------><------><------><------>}
<------><------><------>}
<------><------><------>ctx->pos += chunk_size;
<------><------>}
<------><------>dir_put_page(page);
<------>}
<------>return 0;
}
 
static inline int namecompare(int len, int maxlen,
<------>const char * name, const char * buffer)
{
<------>if (len < maxlen && buffer[len])
<------><------>return 0;
<------>return !memcmp(name, buffer, len);
}
 
/*
 *	minix_find_entry()
 *
 * finds an entry in the specified directory with the wanted name. It
 * returns the cache buffer in which the entry was found, and the entry
 * itself (as a parameter - res_dir). It does NOT read the inode of the
 * entry - you'll have to do that yourself if you want to.
 */
minix_dirent *minix_find_entry(struct dentry *dentry, struct page **res_page)
{
<------>const char * name = dentry->d_name.name;
<------>int namelen = dentry->d_name.len;
<------>struct inode * dir = d_inode(dentry->d_parent);
<------>struct super_block * sb = dir->i_sb;
<------>struct minix_sb_info * sbi = minix_sb(sb);
<------>unsigned long n;
<------>unsigned long npages = dir_pages(dir);
<------>struct page *page = NULL;
<------>char *p;
 
<------>char *namx;
<------>__u32 inumber;
<------>*res_page = NULL;
 
<------>for (n = 0; n < npages; n++) {
<------><------>char *kaddr, *limit;
 
<------><------>page = dir_get_page(dir, n);
<------><------>if (IS_ERR(page))
<------><------><------>continue;
 
<------><------>kaddr = (char*)page_address(page);
<------><------>limit = kaddr + minix_last_byte(dir, n) - sbi->s_dirsize;
<------><------>for (p = kaddr; p <= limit; p = minix_next_entry(p, sbi)) {
<------><------><------>if (sbi->s_version == MINIX_V3) {
<------><------><------><------>minix3_dirent *de3 = (minix3_dirent *)p;
<------><------><------><------>namx = de3->name;
<------><------><------><------>inumber = de3->inode;
 			} else {
<------><------><------><------>minix_dirent *de = (minix_dirent *)p;
<------><------><------><------>namx = de->name;
<------><------><------><------>inumber = de->inode;
<------><------><------>}
<------><------><------>if (!inumber)
<------><------><------><------>continue;
<------><------><------>if (namecompare(namelen, sbi->s_namelen, name, namx))
<------><------><------><------>goto found;
<------><------>}
<------><------>dir_put_page(page);
<------>}
<------>return NULL;
 
found:
<------>*res_page = page;
<------>return (minix_dirent *)p;
}
 
int minix_add_link(struct dentry *dentry, struct inode *inode)
{
<------>struct inode *dir = d_inode(dentry->d_parent);
<------>const char * name = dentry->d_name.name;
<------>int namelen = dentry->d_name.len;
<------>struct super_block * sb = dir->i_sb;
<------>struct minix_sb_info * sbi = minix_sb(sb);
<------>struct page *page = NULL;
<------>unsigned long npages = dir_pages(dir);
<------>unsigned long n;
<------>char *kaddr, *p;
<------>minix_dirent *de;
<------>minix3_dirent *de3;
<------>loff_t pos;
<------>int err;
<------>char *namx = NULL;
<------>__u32 inumber;
 
<------>/*
<------> * We take care of directory expansion in the same loop
<------> * This code plays outside i_size, so it locks the page
<------> * to protect that region.
<------> */
<------>for (n = 0; n <= npages; n++) {
<------><------>char *limit, *dir_end;
 
<------><------>page = dir_get_page(dir, n);
<------><------>err = PTR_ERR(page);
<------><------>if (IS_ERR(page))
<------><------><------>goto out;
<------><------>lock_page(page);
<------><------>kaddr = (char*)page_address(page);
<------><------>dir_end = kaddr + minix_last_byte(dir, n);
<------><------>limit = kaddr + PAGE_SIZE - sbi->s_dirsize;
<------><------>for (p = kaddr; p <= limit; p = minix_next_entry(p, sbi)) {
<------><------><------>de = (minix_dirent *)p;
<------><------><------>de3 = (minix3_dirent *)p;
<------><------><------>if (sbi->s_version == MINIX_V3) {
<------><------><------><------>namx = de3->name;
<------><------><------><------>inumber = de3->inode;
<------><------> 	} else {
  				namx = de->name;
<------><------><------><------>inumber = de->inode;
<------><------><------>}
<------><------><------>if (p == dir_end) {
<------><------><------><------>/* We hit i_size */
<------><------><------><------>if (sbi->s_version == MINIX_V3)
<------><------><------><------><------>de3->inode = 0;
<------><------> 		else
<------><------><------><------><------>de->inode = 0;
<------><------><------><------>goto got_it;
<------><------><------>}
<------><------><------>if (!inumber)
<------><------><------><------>goto got_it;
<------><------><------>err = -EEXIST;
<------><------><------>if (namecompare(namelen, sbi->s_namelen, name, namx))
<------><------><------><------>goto out_unlock;
<------><------>}
<------><------>unlock_page(page);
<------><------>dir_put_page(page);
<------>}
<------>BUG();
<------>return -EINVAL;
 
got_it:
<------>pos = page_offset(page) + p - (char *)page_address(page);
<------>err = minix_prepare_chunk(page, pos, sbi->s_dirsize);
<------>if (err)
<------><------>goto out_unlock;
<------>memcpy (namx, name, namelen);
<------>if (sbi->s_version == MINIX_V3) {
<------><------>memset (namx + namelen, 0, sbi->s_dirsize - namelen - 4);
<------><------>de3->inode = inode->i_ino;
<------>} else {
<------><------>memset (namx + namelen, 0, sbi->s_dirsize - namelen - 2);
<------><------>de->inode = inode->i_ino;
<------>}
<------>err = dir_commit_chunk(page, pos, sbi->s_dirsize);
<------>dir->i_mtime = dir->i_ctime = current_time(dir);
<------>mark_inode_dirty(dir);
out_put:
<------>dir_put_page(page);
out:
<------>return err;
out_unlock:
<------>unlock_page(page);
<------>goto out_put;
}
 
int minix_delete_entry(struct minix_dir_entry *de, struct page *page)
{
<------>struct inode *inode = page->mapping->host;
<------>char *kaddr = page_address(page);
<------>loff_t pos = page_offset(page) + (char*)de - kaddr;
<------>struct minix_sb_info *sbi = minix_sb(inode->i_sb);
<------>unsigned len = sbi->s_dirsize;
<------>int err;
 
<------>lock_page(page);
<------>err = minix_prepare_chunk(page, pos, len);
<------>if (err == 0) {
<------><------>if (sbi->s_version == MINIX_V3)
<------><------><------>((minix3_dirent *) de)->inode = 0;
<------><------>else
<------><------><------>de->inode = 0;
<------><------>err = dir_commit_chunk(page, pos, len);
<------>} else {
<------><------>unlock_page(page);
<------>}
<------>dir_put_page(page);
<------>inode->i_ctime = inode->i_mtime = current_time(inode);
<------>mark_inode_dirty(inode);
<------>return err;
}
 
int minix_make_empty(struct inode *inode, struct inode *dir)
{
<------>struct page *page = grab_cache_page(inode->i_mapping, 0);
<------>struct minix_sb_info *sbi = minix_sb(inode->i_sb);
<------>char *kaddr;
<------>int err;
 
<------>if (!page)
<------><------>return -ENOMEM;
<------>err = minix_prepare_chunk(page, 0, 2 * sbi->s_dirsize);
<------>if (err) {
<------><------>unlock_page(page);
<------><------>goto fail;
<------>}
 
<------>kaddr = kmap_atomic(page);
<------>memset(kaddr, 0, PAGE_SIZE);
 
<------>if (sbi->s_version == MINIX_V3) {
<------><------>minix3_dirent *de3 = (minix3_dirent *)kaddr;
 
<------><------>de3->inode = inode->i_ino;
<------><------>strcpy(de3->name, ".");
<------><------>de3 = minix_next_entry(de3, sbi);
<------><------>de3->inode = dir->i_ino;
<------><------>strcpy(de3->name, "..");
<------>} else {
<------><------>minix_dirent *de = (minix_dirent *)kaddr;
 
<------><------>de->inode = inode->i_ino;
<------><------>strcpy(de->name, ".");
<------><------>de = minix_next_entry(de, sbi);
<------><------>de->inode = dir->i_ino;
<------><------>strcpy(de->name, "..");
<------>}
<------>kunmap_atomic(kaddr);
 
<------>err = dir_commit_chunk(page, 0, 2 * sbi->s_dirsize);
fail:
<------>put_page(page);
<------>return err;
}
 
/*
 * routine to check that the specified directory is empty (for rmdir)
 */
int minix_empty_dir(struct inode * inode)
{
<------>struct page *page = NULL;
<------>unsigned long i, npages = dir_pages(inode);
<------>struct minix_sb_info *sbi = minix_sb(inode->i_sb);
<------>char *name;
<------>__u32 inumber;
 
<------>for (i = 0; i < npages; i++) {
<------><------>char *p, *kaddr, *limit;
 
<------><------>page = dir_get_page(inode, i);
<------><------>if (IS_ERR(page))
<------><------><------>continue;
 
<------><------>kaddr = (char *)page_address(page);
<------><------>limit = kaddr + minix_last_byte(inode, i) - sbi->s_dirsize;
<------><------>for (p = kaddr; p <= limit; p = minix_next_entry(p, sbi)) {
<------><------><------>if (sbi->s_version == MINIX_V3) {
<------><------><------><------>minix3_dirent *de3 = (minix3_dirent *)p;
<------><------><------><------>name = de3->name;
<------><------><------><------>inumber = de3->inode;
<------><------><------>} else {
<------><------><------><------>minix_dirent *de = (minix_dirent *)p;
<------><------><------><------>name = de->name;
<------><------><------><------>inumber = de->inode;
<------><------><------>}
 
<------><------><------>if (inumber != 0) {
<------><------><------><------>/* check for . and .. */
<------><------><------><------>if (name[0] != '.')
<------><------><------><------><------>goto not_empty;
<------><------><------><------>if (!name[1]) {
<------><------><------><------><------>if (inumber != inode->i_ino)
<------><------><------><------><------><------>goto not_empty;
<------><------><------><------>} else if (name[1] != '.')
<------><------><------><------><------>goto not_empty;
<------><------><------><------>else if (name[2])
<------><------><------><------><------>goto not_empty;
<------><------><------>}
<------><------>}
<------><------>dir_put_page(page);
<------>}
<------>return 1;
 
not_empty:
<------>dir_put_page(page);
<------>return 0;
}
 
/* Releases the page */
void minix_set_link(struct minix_dir_entry *de, struct page *page,
<------>struct inode *inode)
{
<------>struct inode *dir = page->mapping->host;
<------>struct minix_sb_info *sbi = minix_sb(dir->i_sb);
<------>loff_t pos = page_offset(page) +
<------><------><------>(char *)de-(char*)page_address(page);
<------>int err;
 
<------>lock_page(page);
 
<------>err = minix_prepare_chunk(page, pos, sbi->s_dirsize);
<------>if (err == 0) {
<------><------>if (sbi->s_version == MINIX_V3)
<------><------><------>((minix3_dirent *) de)->inode = inode->i_ino;
<------><------>else
<------><------><------>de->inode = inode->i_ino;
<------><------>err = dir_commit_chunk(page, pos, sbi->s_dirsize);
<------>} else {
<------><------>unlock_page(page);
<------>}
<------>dir_put_page(page);
<------>dir->i_mtime = dir->i_ctime = current_time(dir);
<------>mark_inode_dirty(dir);
}
 
struct minix_dir_entry * minix_dotdot (struct inode *dir, struct page **p)
{
<------>struct page *page = dir_get_page(dir, 0);
<------>struct minix_sb_info *sbi = minix_sb(dir->i_sb);
<------>struct minix_dir_entry *de = NULL;
 
<------>if (!IS_ERR(page)) {
<------><------>de = minix_next_entry(page_address(page), sbi);
<------><------>*p = page;
<------>}
<------>return de;
}
 
ino_t minix_inode_by_name(struct dentry *dentry)
{
<------>struct page *page;
<------>struct minix_dir_entry *de = minix_find_entry(dentry, &page);
<------>ino_t res = 0;
 
<------>if (de) {
<------><------>struct address_space *mapping = page->mapping;
<------><------>struct inode *inode = mapping->host;
<------><------>struct minix_sb_info *sbi = minix_sb(inode->i_sb);
 
<------><------>if (sbi->s_version == MINIX_V3)
<------><------><------>res = ((minix3_dirent *) de)->inode;
<------><------>else
<------><------><------>res = de->inode;
<------><------>dir_put_page(page);
<------>}
<------>return res;
}