kernel-ark/fs/minix/dir.c
Andries Brouwer 939b00df03 [PATCH] Minix V3 support
This morning I needed to read a Minix V3 filesystem, but unfortunately my
2.6.19 did not support that, and neither did the downloaded 2.6.20rc4.

Fortunately, google told me that Daniel Aragones had already done the work,
patch found at http://www.terra.es/personal2/danarag/

Unfortunaly, looking at the patch was painful to my eyes, so I polished it
a bit before applying.  The resulting kernel boots, and reads the
filesystem it needed to read.

Signed-off-by: Daniel Aragones <danarag@gmail.com>
Signed-off-by: Andries Brouwer <aeb@cwi.nl>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-02-12 09:48:31 -08:00

469 lines
11 KiB
C

/*
* 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/highmem.h>
#include <linux/smp_lock.h>
typedef struct minix_dir_entry minix_dirent;
typedef struct minix3_dir_entry minix3_dirent;
static int minix_readdir(struct file *, void *, filldir_t);
const 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);
}
/*
* 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_CACHE_SIZE;
if (page_nr == (inode->i_size >> PAGE_CACHE_SHIFT))
last_byte = inode->i_size & (PAGE_CACHE_SIZE - 1);
return last_byte;
}
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_DIRSYNC(dir))
err = write_one_page(page, 1);
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)) {
wait_on_page_locked(page);
kmap(page);
if (!PageUptodate(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_path.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 = minix_sb(sb);
unsigned chunk_size = sbi->s_dirsize;
char *name;
__u32 inumber;
lock_kernel();
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 + minix_last_byte(inode, n) - chunk_size;
for ( ; 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) {
int over;
unsigned l = strnlen(name, sbi->s_namelen);
offset = p - kaddr;
over = filldir(dirent, name, l,
(n << PAGE_CACHE_SHIFT) | offset,
inumber, DT_UNKNOWN);
if (over) {
dir_put_page(page);
goto done;
}
}
}
dir_put_page(page);
}
done:
filp->f_pos = (n << PAGE_CACHE_SHIFT) | offset;
unlock_kernel();
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 = 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 = 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 = 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;
unsigned from, to;
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_CACHE_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:
from = p - (char*)page_address(page);
to = from + sbi->s_dirsize;
err = page->mapping->a_ops->prepare_write(NULL, page, from, to);
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, from, to);
dir->i_mtime = dir->i_ctime = CURRENT_TIME_SEC;
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 address_space *mapping = page->mapping;
struct inode *inode = (struct inode*)mapping->host;
char *kaddr = page_address(page);
unsigned from = (char*)de - kaddr;
unsigned to = from + minix_sb(inode->i_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);
} else {
unlock_page(page);
}
dir_put_page(page);
inode->i_ctime = inode->i_mtime = CURRENT_TIME_SEC;
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 = minix_sb(inode->i_sb);
char *kaddr;
int err;
if (!page)
return -ENOMEM;
err = mapping->a_ops->prepare_write(NULL, page, 0, 2 * sbi->s_dirsize);
if (err) {
unlock_page(page);
goto fail;
}
kaddr = kmap_atomic(page, KM_USER0);
memset(kaddr, 0, PAGE_CACHE_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, KM_USER0);
err = dir_commit_chunk(page, 0, 2 * sbi->s_dirsize);
fail:
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 = 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 = (struct inode*)page->mapping->host;
struct minix_sb_info *sbi = minix_sb(dir->i_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);
} else {
unlock_page(page);
}
dir_put_page(page);
dir->i_mtime = dir->i_ctime = CURRENT_TIME_SEC;
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) {
res = de->inode;
dir_put_page(page);
}
return res;
}