368 lines
8.4 KiB
C
368 lines
8.4 KiB
C
/*
|
|
* linux/fs/sysv/dir.c
|
|
*
|
|
* minix/dir.c
|
|
* Copyright (C) 1991, 1992 Linus Torvalds
|
|
*
|
|
* coh/dir.c
|
|
* Copyright (C) 1993 Pascal Haible, Bruno Haible
|
|
*
|
|
* sysv/dir.c
|
|
* Copyright (C) 1993 Bruno Haible
|
|
*
|
|
* SystemV/Coherent directory handling functions
|
|
*/
|
|
|
|
#include <linux/pagemap.h>
|
|
#include <linux/highmem.h>
|
|
#include <linux/swap.h>
|
|
#include "sysv.h"
|
|
|
|
static int sysv_readdir(struct file *, struct dir_context *);
|
|
|
|
const struct file_operations sysv_dir_operations = {
|
|
.llseek = generic_file_llseek,
|
|
.read = generic_read_dir,
|
|
.iterate_shared = sysv_readdir,
|
|
.fsync = generic_file_fsync,
|
|
};
|
|
|
|
static inline void dir_put_page(struct page *page)
|
|
{
|
|
kunmap(page);
|
|
put_page(page);
|
|
}
|
|
|
|
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 int sysv_readdir(struct file *file, struct dir_context *ctx)
|
|
{
|
|
unsigned long pos = ctx->pos;
|
|
struct inode *inode = file_inode(file);
|
|
struct super_block *sb = inode->i_sb;
|
|
unsigned long npages = dir_pages(inode);
|
|
unsigned offset;
|
|
unsigned long n;
|
|
|
|
ctx->pos = pos = (pos + SYSV_DIRSIZE-1) & ~(SYSV_DIRSIZE-1);
|
|
if (pos >= inode->i_size)
|
|
return 0;
|
|
|
|
offset = pos & ~PAGE_MASK;
|
|
n = pos >> PAGE_SHIFT;
|
|
|
|
for ( ; n < npages; n++, offset = 0) {
|
|
char *kaddr, *limit;
|
|
struct sysv_dir_entry *de;
|
|
struct page *page = dir_get_page(inode, n);
|
|
|
|
if (IS_ERR(page))
|
|
continue;
|
|
kaddr = (char *)page_address(page);
|
|
de = (struct sysv_dir_entry *)(kaddr+offset);
|
|
limit = kaddr + PAGE_SIZE - SYSV_DIRSIZE;
|
|
for ( ;(char*)de <= limit; de++, ctx->pos += sizeof(*de)) {
|
|
char *name = de->name;
|
|
|
|
if (!de->inode)
|
|
continue;
|
|
|
|
if (!dir_emit(ctx, name, strnlen(name,SYSV_NAMELEN),
|
|
fs16_to_cpu(SYSV_SB(sb), de->inode),
|
|
DT_UNKNOWN)) {
|
|
dir_put_page(page);
|
|
return 0;
|
|
}
|
|
}
|
|
dir_put_page(page);
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
/* compare strings: name[0..len-1] (not zero-terminated) and
|
|
* buffer[0..] (filled with zeroes up to buffer[0..maxlen-1])
|
|
*/
|
|
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);
|
|
}
|
|
|
|
/*
|
|
* sysv_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.
|
|
*/
|
|
struct sysv_dir_entry *sysv_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);
|
|
unsigned long start, n;
|
|
unsigned long npages = dir_pages(dir);
|
|
struct page *page = NULL;
|
|
struct sysv_dir_entry *de;
|
|
|
|
*res_page = NULL;
|
|
|
|
start = SYSV_I(dir)->i_dir_start_lookup;
|
|
if (start >= npages)
|
|
start = 0;
|
|
n = start;
|
|
|
|
do {
|
|
char *kaddr;
|
|
page = dir_get_page(dir, n);
|
|
if (!IS_ERR(page)) {
|
|
kaddr = (char*)page_address(page);
|
|
de = (struct sysv_dir_entry *) kaddr;
|
|
kaddr += PAGE_SIZE - SYSV_DIRSIZE;
|
|
for ( ; (char *) de <= kaddr ; de++) {
|
|
if (!de->inode)
|
|
continue;
|
|
if (namecompare(namelen, SYSV_NAMELEN,
|
|
name, de->name))
|
|
goto found;
|
|
}
|
|
dir_put_page(page);
|
|
}
|
|
|
|
if (++n >= npages)
|
|
n = 0;
|
|
} while (n != start);
|
|
|
|
return NULL;
|
|
|
|
found:
|
|
SYSV_I(dir)->i_dir_start_lookup = n;
|
|
*res_page = page;
|
|
return de;
|
|
}
|
|
|
|
int sysv_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 page *page = NULL;
|
|
struct sysv_dir_entry * de;
|
|
unsigned long npages = dir_pages(dir);
|
|
unsigned long n;
|
|
char *kaddr;
|
|
loff_t pos;
|
|
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 = (struct sysv_dir_entry *)kaddr;
|
|
kaddr += PAGE_SIZE - SYSV_DIRSIZE;
|
|
while ((char *)de <= kaddr) {
|
|
if (!de->inode)
|
|
goto got_it;
|
|
err = -EEXIST;
|
|
if (namecompare(namelen, SYSV_NAMELEN, name, de->name))
|
|
goto out_page;
|
|
de++;
|
|
}
|
|
dir_put_page(page);
|
|
}
|
|
BUG();
|
|
return -EINVAL;
|
|
|
|
got_it:
|
|
pos = page_offset(page) +
|
|
(char*)de - (char*)page_address(page);
|
|
lock_page(page);
|
|
err = sysv_prepare_chunk(page, pos, SYSV_DIRSIZE);
|
|
if (err)
|
|
goto out_unlock;
|
|
memcpy (de->name, name, namelen);
|
|
memset (de->name + namelen, 0, SYSV_DIRSIZE - namelen - 2);
|
|
de->inode = cpu_to_fs16(SYSV_SB(inode->i_sb), inode->i_ino);
|
|
err = dir_commit_chunk(page, pos, SYSV_DIRSIZE);
|
|
dir->i_mtime = dir->i_ctime = current_time(dir);
|
|
mark_inode_dirty(dir);
|
|
out_page:
|
|
dir_put_page(page);
|
|
out:
|
|
return err;
|
|
out_unlock:
|
|
unlock_page(page);
|
|
goto out_page;
|
|
}
|
|
|
|
int sysv_delete_entry(struct sysv_dir_entry *de, struct page *page)
|
|
{
|
|
struct inode *inode = page->mapping->host;
|
|
char *kaddr = (char*)page_address(page);
|
|
loff_t pos = page_offset(page) + (char *)de - kaddr;
|
|
int err;
|
|
|
|
lock_page(page);
|
|
err = sysv_prepare_chunk(page, pos, SYSV_DIRSIZE);
|
|
BUG_ON(err);
|
|
de->inode = 0;
|
|
err = dir_commit_chunk(page, pos, SYSV_DIRSIZE);
|
|
dir_put_page(page);
|
|
inode->i_ctime = inode->i_mtime = current_time(inode);
|
|
mark_inode_dirty(inode);
|
|
return err;
|
|
}
|
|
|
|
int sysv_make_empty(struct inode *inode, struct inode *dir)
|
|
{
|
|
struct page *page = grab_cache_page(inode->i_mapping, 0);
|
|
struct sysv_dir_entry * de;
|
|
char *base;
|
|
int err;
|
|
|
|
if (!page)
|
|
return -ENOMEM;
|
|
err = sysv_prepare_chunk(page, 0, 2 * SYSV_DIRSIZE);
|
|
if (err) {
|
|
unlock_page(page);
|
|
goto fail;
|
|
}
|
|
kmap(page);
|
|
|
|
base = (char*)page_address(page);
|
|
memset(base, 0, PAGE_SIZE);
|
|
|
|
de = (struct sysv_dir_entry *) base;
|
|
de->inode = cpu_to_fs16(SYSV_SB(inode->i_sb), inode->i_ino);
|
|
strcpy(de->name,".");
|
|
de++;
|
|
de->inode = cpu_to_fs16(SYSV_SB(inode->i_sb), dir->i_ino);
|
|
strcpy(de->name,"..");
|
|
|
|
kunmap(page);
|
|
err = dir_commit_chunk(page, 0, 2 * SYSV_DIRSIZE);
|
|
fail:
|
|
put_page(page);
|
|
return err;
|
|
}
|
|
|
|
/*
|
|
* routine to check that the specified directory is empty (for rmdir)
|
|
*/
|
|
int sysv_empty_dir(struct inode * inode)
|
|
{
|
|
struct super_block *sb = inode->i_sb;
|
|
struct page *page = NULL;
|
|
unsigned long i, npages = dir_pages(inode);
|
|
|
|
for (i = 0; i < npages; i++) {
|
|
char *kaddr;
|
|
struct sysv_dir_entry * de;
|
|
page = dir_get_page(inode, i);
|
|
|
|
if (IS_ERR(page))
|
|
continue;
|
|
|
|
kaddr = (char *)page_address(page);
|
|
de = (struct sysv_dir_entry *)kaddr;
|
|
kaddr += PAGE_SIZE-SYSV_DIRSIZE;
|
|
|
|
for ( ;(char *)de <= kaddr; de++) {
|
|
if (!de->inode)
|
|
continue;
|
|
/* check for . and .. */
|
|
if (de->name[0] != '.')
|
|
goto not_empty;
|
|
if (!de->name[1]) {
|
|
if (de->inode == cpu_to_fs16(SYSV_SB(sb),
|
|
inode->i_ino))
|
|
continue;
|
|
goto not_empty;
|
|
}
|
|
if (de->name[1] != '.' || de->name[2])
|
|
goto not_empty;
|
|
}
|
|
dir_put_page(page);
|
|
}
|
|
return 1;
|
|
|
|
not_empty:
|
|
dir_put_page(page);
|
|
return 0;
|
|
}
|
|
|
|
/* Releases the page */
|
|
void sysv_set_link(struct sysv_dir_entry *de, struct page *page,
|
|
struct inode *inode)
|
|
{
|
|
struct inode *dir = page->mapping->host;
|
|
loff_t pos = page_offset(page) +
|
|
(char *)de-(char*)page_address(page);
|
|
int err;
|
|
|
|
lock_page(page);
|
|
err = sysv_prepare_chunk(page, pos, SYSV_DIRSIZE);
|
|
BUG_ON(err);
|
|
de->inode = cpu_to_fs16(SYSV_SB(inode->i_sb), inode->i_ino);
|
|
err = dir_commit_chunk(page, pos, SYSV_DIRSIZE);
|
|
dir_put_page(page);
|
|
dir->i_mtime = dir->i_ctime = current_time(dir);
|
|
mark_inode_dirty(dir);
|
|
}
|
|
|
|
struct sysv_dir_entry * sysv_dotdot (struct inode *dir, struct page **p)
|
|
{
|
|
struct page *page = dir_get_page(dir, 0);
|
|
struct sysv_dir_entry *de = NULL;
|
|
|
|
if (!IS_ERR(page)) {
|
|
de = (struct sysv_dir_entry*) page_address(page) + 1;
|
|
*p = page;
|
|
}
|
|
return de;
|
|
}
|
|
|
|
ino_t sysv_inode_by_name(struct dentry *dentry)
|
|
{
|
|
struct page *page;
|
|
struct sysv_dir_entry *de = sysv_find_entry (dentry, &page);
|
|
ino_t res = 0;
|
|
|
|
if (de) {
|
|
res = fs16_to_cpu(SYSV_SB(dentry->d_sb), de->inode);
|
|
dir_put_page(page);
|
|
}
|
|
return res;
|
|
}
|