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/*
* linux/fs/minix/dir.c
*
* Copyright (C) 1991, 1992 Linus Torvalds
*
* minix directory handling functions
*/
#include <linux/fs.h>
#include <linux/minix_fs.h>
#include <linux/pagemap.h>
typedef struct minix_dir_entry minix_dirent;
static int minix_readdir(struct file *, void *, filldir_t);
struct file_operations minix_dir_operations = {
read: generic_read_dir,
readdir: minix_readdir,
fsync: minix_sync_file,
};
static inline void dir_put_page(struct page *page)
{
kunmap(page);
page_cache_release(page);
}
static inline unsigned long dir_pages(struct inode *inode)
{
return (inode->i_size+PAGE_CACHE_SIZE-1)>>PAGE_CACHE_SHIFT;
}
static int dir_commit_chunk(struct page *page, unsigned from, unsigned to)
{
struct inode *dir = (struct inode *)page->mapping->host;
int err = 0;
page->mapping->a_ops->commit_write(NULL, page, from, to);
if (IS_SYNC(dir)) {
int err2;
err = writeout_one_page(page);
err2 = waitfor_one_page(page);
if (err == 0)
err = err2;
}
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_cache_page(mapping, n,
(filler_t*)mapping->a_ops->readpage, NULL);
if (!IS_ERR(page)) {
wait_on_page(page);
kmap(page);
if (!Page_Uptodate(page))
goto fail;
}
return page;
fail:
dir_put_page(page);
return ERR_PTR(-EIO);
}
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 * filp, void * dirent, filldir_t filldir)
{
unsigned long pos = filp->f_pos;
struct inode *inode = filp->f_dentry->d_inode;
struct super_block *sb = inode->i_sb;
unsigned offset = pos & ~PAGE_CACHE_MASK;
unsigned long n = pos >> PAGE_CACHE_SHIFT;
unsigned long npages = dir_pages(inode);
struct minix_sb_info *sbi = &sb->u.minix_sb;
unsigned chunk_size = sbi->s_dirsize;
pos = (pos + chunk_size-1) & ~(chunk_size-1);
if (pos >= inode->i_size)
goto done;
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 + PAGE_CACHE_SIZE - chunk_size;
for ( ; p <= limit ; p = minix_next_entry(p, sbi)) {
minix_dirent *de = (minix_dirent *)p;
if (de->inode) {
int over;
unsigned l = strnlen(de->name,sbi->s_namelen);
offset = p - kaddr;
over = filldir(dirent, de->name, l,
(n<<PAGE_CACHE_SHIFT) | offset,
de->inode, DT_UNKNOWN);
if (over) {
dir_put_page(page);
goto done;
}
}
}
dir_put_page(page);
}
done:
filp->f_pos = (n << PAGE_CACHE_SHIFT) | offset;
UPDATE_ATIME(inode);
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 = dentry->d_parent->d_inode;
struct super_block * sb = dir->i_sb;
struct minix_sb_info * sbi = &sb->u.minix_sb;
unsigned long n;
unsigned long npages = dir_pages(dir);
struct page *page = NULL;
struct minix_dir_entry *de;
*res_page = NULL;
for (n = 0; n < npages; n++) {
char *kaddr;
page = dir_get_page(dir, n);
if (IS_ERR(page))
continue;
kaddr = (char*)page_address(page);
de = (struct minix_dir_entry *) kaddr;
kaddr += PAGE_CACHE_SIZE - sbi->s_dirsize;
for ( ; (char *) de <= kaddr ; de = minix_next_entry(de,sbi)) {
if (!de->inode)
continue;
if (namecompare(namelen,sbi->s_namelen,name,de->name))
goto found;
}
dir_put_page(page);
}
return NULL;
found:
*res_page = page;
return de;
}
int minix_add_link(struct dentry *dentry, struct inode *inode)
{
struct inode *dir = dentry->d_parent->d_inode;
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 = &sb->u.minix_sb;
struct page *page = NULL;
struct minix_dir_entry * de;
unsigned long npages = dir_pages(dir);
unsigned long n;
char *kaddr;
unsigned from, to;
int err;
/* We take care of directory expansion in the same loop */
for (n = 0; n <= npages; n++) {
page = dir_get_page(dir, n);
err = PTR_ERR(page);
if (IS_ERR(page))
goto out;
kaddr = (char*)page_address(page);
de = (minix_dirent *)kaddr;
kaddr += PAGE_CACHE_SIZE - sbi->s_dirsize;
while ((char *)de <= kaddr) {
if (!de->inode)
goto got_it;
err = -EEXIST;
if (namecompare(namelen,sbi->s_namelen,name,de->name))
goto out_page;
de = minix_next_entry(de, sbi);
}
dir_put_page(page);
}
BUG();
return -EINVAL;
got_it:
from = (char*)de - (char*)page_address(page);
to = from + sbi->s_dirsize;
lock_page(page);
err = page->mapping->a_ops->prepare_write(NULL, page, from, to);
if (err)
goto out_unlock;
memcpy (de->name, name, namelen);
memset (de->name + namelen, 0, sbi->s_dirsize - namelen - 2);
de->inode = inode->i_ino;
err = dir_commit_chunk(page, from, to);
dir->i_mtime = dir->i_ctime = CURRENT_TIME;
mark_inode_dirty(dir);
out_unlock:
UnlockPage(page);
out_page:
dir_put_page(page);
out:
return err;
}
int minix_delete_entry(struct minix_dir_entry *de, struct page *page)
{
struct address_space *mapping = page->mapping;
struct inode *inode = (struct inode*)mapping->host;
char *kaddr = (char*)page_address(page);
unsigned from = (char*)de - kaddr;
unsigned to = from + inode->i_sb->u.minix_sb.s_dirsize;
int err;
lock_page(page);
err = mapping->a_ops->prepare_write(NULL, page, from, to);
if (err == 0) {
de->inode = 0;
err = dir_commit_chunk(page, from, to);
}
UnlockPage(page);
dir_put_page(page);
inode->i_ctime = inode->i_mtime = CURRENT_TIME;
mark_inode_dirty(inode);
return err;
}
int minix_make_empty(struct inode *inode, struct inode *dir)
{
struct address_space *mapping = inode->i_mapping;
struct page *page = grab_cache_page(mapping, 0);
struct minix_sb_info * sbi = &inode->i_sb->u.minix_sb;
struct minix_dir_entry * de;
char *base;
int err;
if (!page)
return -ENOMEM;
err = mapping->a_ops->prepare_write(NULL, page, 0, 2 * sbi->s_dirsize);
if (err)
goto fail;
base = (char*)page_address(page);
memset(base, 0, PAGE_CACHE_SIZE);
de = (struct minix_dir_entry *) base;
de->inode = inode->i_ino;
strcpy(de->name,".");
de = minix_next_entry(de, sbi);
de->inode = dir->i_ino;
strcpy(de->name,"..");
err = dir_commit_chunk(page, 0, 2 * sbi->s_dirsize);
fail:
UnlockPage(page);
page_cache_release(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 = &inode->i_sb->u.minix_sb;
for (i = 0; i < npages; i++) {
char *kaddr;
minix_dirent * de;
page = dir_get_page(inode, i);
if (IS_ERR(page))
continue;
kaddr = (char *)page_address(page);
de = (minix_dirent *)kaddr;
kaddr += PAGE_CACHE_SIZE - sbi->s_dirsize;
while ((char *)de <= kaddr) {
if (de->inode != 0) {
/* check for . and .. */
if (de->name[0] != '.')
goto not_empty;
if (!de->name[1]) {
if (de->inode != inode->i_ino)
goto not_empty;
} else if (de->name[1] != '.')
goto not_empty;
else if (de->name[2])
goto not_empty;
}
de = minix_next_entry(de, sbi);
}
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 = (struct inode*)page->mapping->host;
struct minix_sb_info *sbi = &dir->i_sb->u.minix_sb;
unsigned from = (char *)de-(char*)page_address(page);
unsigned to = from + sbi->s_dirsize;
int err;
lock_page(page);
err = page->mapping->a_ops->prepare_write(NULL, page, from, to);
if (err == 0) {
de->inode = inode->i_ino;
err = dir_commit_chunk(page, from, to);
}
UnlockPage(page);
dir_put_page(page);
dir->i_mtime = dir->i_ctime = CURRENT_TIME;
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 = &dir->i_sb->u.minix_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) {
res = de->inode;
dir_put_page(page);
}
return res;
}
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