kernel-ark/fs/bfs/dir.c
Dmitri Vorobiev f433dc5634 Fixes to the BFS filesystem driver
I found a few bugs in the BFS driver.  Detailed description of the bugs as
well as the steps to reproduce the errors are given in the kernel bugzilla.
 Please follow these links for more information:

http://bugzilla.kernel.org/show_bug.cgi?id=9363
http://bugzilla.kernel.org/show_bug.cgi?id=9364
http://bugzilla.kernel.org/show_bug.cgi?id=9365
http://bugzilla.kernel.org/show_bug.cgi?id=9366

This patch fixes the bugs described above.  Besides, the patch introduces
coding style changes to make the BFS driver conform to the requirements
specified for Linux kernel code.  Finally, I made a few cosmetic changes
such as removal of trivial debug output.

Also, the patch removes the fields `si_lf_ioff' and `si_lf_sblk' of the
in-core superblock structure.  These fields are initialized but never
actually used.

If you are wondering why I need BFS, here is the answer: I am using this
driver in the context of Linux kernel classes I am teaching in the Moscow
State University and in the International Institute of Information
Technology in Pune, India.

Signed-off-by: Dmitri Vorobiev <dmitri.vorobiev@gmail.com>
Cc: Tigran Aivazian <tigran@veritas.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-11-14 18:45:40 -08:00

371 lines
8.4 KiB
C

/*
* fs/bfs/dir.c
* BFS directory operations.
* Copyright (C) 1999,2000 Tigran Aivazian <tigran@veritas.com>
* Made endianness-clean by Andrew Stribblehill <ads@wompom.org> 2005
*/
#include <linux/time.h>
#include <linux/string.h>
#include <linux/fs.h>
#include <linux/smp_lock.h>
#include <linux/buffer_head.h>
#include <linux/sched.h>
#include "bfs.h"
#undef DEBUG
#ifdef DEBUG
#define dprintf(x...) printf(x)
#else
#define dprintf(x...)
#endif
static int bfs_add_entry(struct inode *dir, const unsigned char *name,
int namelen, int ino);
static struct buffer_head *bfs_find_entry(struct inode *dir,
const unsigned char *name, int namelen,
struct bfs_dirent **res_dir);
static int bfs_readdir(struct file *f, void *dirent, filldir_t filldir)
{
struct inode *dir = f->f_path.dentry->d_inode;
struct buffer_head *bh;
struct bfs_dirent *de;
unsigned int offset;
int block;
lock_kernel();
if (f->f_pos & (BFS_DIRENT_SIZE - 1)) {
printf("Bad f_pos=%08lx for %s:%08lx\n",
(unsigned long)f->f_pos,
dir->i_sb->s_id, dir->i_ino);
unlock_kernel();
return -EBADF;
}
while (f->f_pos < dir->i_size) {
offset = f->f_pos & (BFS_BSIZE - 1);
block = BFS_I(dir)->i_sblock + (f->f_pos >> BFS_BSIZE_BITS);
bh = sb_bread(dir->i_sb, block);
if (!bh) {
f->f_pos += BFS_BSIZE - offset;
continue;
}
do {
de = (struct bfs_dirent *)(bh->b_data + offset);
if (de->ino) {
int size = strnlen(de->name, BFS_NAMELEN);
if (filldir(dirent, de->name, size, f->f_pos,
le16_to_cpu(de->ino),
DT_UNKNOWN) < 0) {
brelse(bh);
unlock_kernel();
return 0;
}
}
offset += BFS_DIRENT_SIZE;
f->f_pos += BFS_DIRENT_SIZE;
} while ((offset < BFS_BSIZE) && (f->f_pos < dir->i_size));
brelse(bh);
}
unlock_kernel();
return 0;
}
const struct file_operations bfs_dir_operations = {
.read = generic_read_dir,
.readdir = bfs_readdir,
.fsync = file_fsync,
};
extern void dump_imap(const char *, struct super_block *);
static int bfs_create(struct inode *dir, struct dentry *dentry, int mode,
struct nameidata *nd)
{
int err;
struct inode *inode;
struct super_block *s = dir->i_sb;
struct bfs_sb_info *info = BFS_SB(s);
unsigned long ino;
inode = new_inode(s);
if (!inode)
return -ENOSPC;
lock_kernel();
ino = find_first_zero_bit(info->si_imap, info->si_lasti);
if (ino > info->si_lasti) {
unlock_kernel();
iput(inode);
return -ENOSPC;
}
set_bit(ino, info->si_imap);
info->si_freei--;
inode->i_uid = current->fsuid;
inode->i_gid = (dir->i_mode & S_ISGID) ? dir->i_gid : current->fsgid;
inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME_SEC;
inode->i_blocks = 0;
inode->i_op = &bfs_file_inops;
inode->i_fop = &bfs_file_operations;
inode->i_mapping->a_ops = &bfs_aops;
inode->i_mode = mode;
inode->i_ino = ino;
BFS_I(inode)->i_dsk_ino = ino;
BFS_I(inode)->i_sblock = 0;
BFS_I(inode)->i_eblock = 0;
insert_inode_hash(inode);
mark_inode_dirty(inode);
dump_imap("create", s);
err = bfs_add_entry(dir, dentry->d_name.name, dentry->d_name.len,
inode->i_ino);
if (err) {
inode_dec_link_count(inode);
iput(inode);
unlock_kernel();
return err;
}
unlock_kernel();
d_instantiate(dentry, inode);
return 0;
}
static struct dentry *bfs_lookup(struct inode *dir, struct dentry *dentry,
struct nameidata *nd)
{
struct inode *inode = NULL;
struct buffer_head *bh;
struct bfs_dirent *de;
if (dentry->d_name.len > BFS_NAMELEN)
return ERR_PTR(-ENAMETOOLONG);
lock_kernel();
bh = bfs_find_entry(dir, dentry->d_name.name, dentry->d_name.len, &de);
if (bh) {
unsigned long ino = (unsigned long)le16_to_cpu(de->ino);
brelse(bh);
inode = iget(dir->i_sb, ino);
if (!inode) {
unlock_kernel();
return ERR_PTR(-EACCES);
}
}
unlock_kernel();
d_add(dentry, inode);
return NULL;
}
static int bfs_link(struct dentry *old, struct inode *dir,
struct dentry *new)
{
struct inode *inode = old->d_inode;
int err;
lock_kernel();
err = bfs_add_entry(dir, new->d_name.name, new->d_name.len,
inode->i_ino);
if (err) {
unlock_kernel();
return err;
}
inc_nlink(inode);
inode->i_ctime = CURRENT_TIME_SEC;
mark_inode_dirty(inode);
atomic_inc(&inode->i_count);
d_instantiate(new, inode);
unlock_kernel();
return 0;
}
static int bfs_unlink(struct inode *dir, struct dentry *dentry)
{
int error = -ENOENT;
struct inode *inode;
struct buffer_head *bh;
struct bfs_dirent *de;
inode = dentry->d_inode;
lock_kernel();
bh = bfs_find_entry(dir, dentry->d_name.name, dentry->d_name.len, &de);
if (!bh || (le16_to_cpu(de->ino) != inode->i_ino))
goto out_brelse;
if (!inode->i_nlink) {
printf("unlinking non-existent file %s:%lu (nlink=%d)\n",
inode->i_sb->s_id, inode->i_ino,
inode->i_nlink);
inode->i_nlink = 1;
}
de->ino = 0;
mark_buffer_dirty(bh);
dir->i_ctime = dir->i_mtime = CURRENT_TIME_SEC;
mark_inode_dirty(dir);
inode->i_ctime = dir->i_ctime;
inode_dec_link_count(inode);
error = 0;
out_brelse:
brelse(bh);
unlock_kernel();
return error;
}
static int bfs_rename(struct inode *old_dir, struct dentry *old_dentry,
struct inode *new_dir, struct dentry *new_dentry)
{
struct inode *old_inode, *new_inode;
struct buffer_head *old_bh, *new_bh;
struct bfs_dirent *old_de, *new_de;
int error = -ENOENT;
old_bh = new_bh = NULL;
old_inode = old_dentry->d_inode;
if (S_ISDIR(old_inode->i_mode))
return -EINVAL;
lock_kernel();
old_bh = bfs_find_entry(old_dir,
old_dentry->d_name.name,
old_dentry->d_name.len, &old_de);
if (!old_bh || (le16_to_cpu(old_de->ino) != old_inode->i_ino))
goto end_rename;
error = -EPERM;
new_inode = new_dentry->d_inode;
new_bh = bfs_find_entry(new_dir,
new_dentry->d_name.name,
new_dentry->d_name.len, &new_de);
if (new_bh && !new_inode) {
brelse(new_bh);
new_bh = NULL;
}
if (!new_bh) {
error = bfs_add_entry(new_dir,
new_dentry->d_name.name,
new_dentry->d_name.len,
old_inode->i_ino);
if (error)
goto end_rename;
}
old_de->ino = 0;
old_dir->i_ctime = old_dir->i_mtime = CURRENT_TIME_SEC;
mark_inode_dirty(old_dir);
if (new_inode) {
new_inode->i_ctime = CURRENT_TIME_SEC;
inode_dec_link_count(new_inode);
}
mark_buffer_dirty(old_bh);
error = 0;
end_rename:
unlock_kernel();
brelse(old_bh);
brelse(new_bh);
return error;
}
const struct inode_operations bfs_dir_inops = {
.create = bfs_create,
.lookup = bfs_lookup,
.link = bfs_link,
.unlink = bfs_unlink,
.rename = bfs_rename,
};
static int bfs_add_entry(struct inode *dir, const unsigned char *name,
int namelen, int ino)
{
struct buffer_head *bh;
struct bfs_dirent *de;
int block, sblock, eblock, off, pos;
int i;
dprintf("name=%s, namelen=%d\n", name, namelen);
if (!namelen)
return -ENOENT;
if (namelen > BFS_NAMELEN)
return -ENAMETOOLONG;
sblock = BFS_I(dir)->i_sblock;
eblock = BFS_I(dir)->i_eblock;
for (block = sblock; block <= eblock; block++) {
bh = sb_bread(dir->i_sb, block);
if (!bh)
return -ENOSPC;
for (off = 0; off < BFS_BSIZE; off += BFS_DIRENT_SIZE) {
de = (struct bfs_dirent *)(bh->b_data + off);
if (!de->ino) {
pos = (block - sblock) * BFS_BSIZE + off;
if (pos >= dir->i_size) {
dir->i_size += BFS_DIRENT_SIZE;
dir->i_ctime = CURRENT_TIME_SEC;
}
dir->i_mtime = CURRENT_TIME_SEC;
mark_inode_dirty(dir);
de->ino = cpu_to_le16((u16)ino);
for (i = 0; i < BFS_NAMELEN; i++)
de->name[i] =
(i < namelen) ? name[i] : 0;
mark_buffer_dirty(bh);
brelse(bh);
return 0;
}
}
brelse(bh);
}
return -ENOSPC;
}
static inline int bfs_namecmp(int len, const unsigned char *name,
const char *buffer)
{
if ((len < BFS_NAMELEN) && buffer[len])
return 0;
return !memcmp(name, buffer, len);
}
static struct buffer_head *bfs_find_entry(struct inode *dir,
const unsigned char *name, int namelen,
struct bfs_dirent **res_dir)
{
unsigned long block = 0, offset = 0;
struct buffer_head *bh = NULL;
struct bfs_dirent *de;
*res_dir = NULL;
if (namelen > BFS_NAMELEN)
return NULL;
while (block * BFS_BSIZE + offset < dir->i_size) {
if (!bh) {
bh = sb_bread(dir->i_sb, BFS_I(dir)->i_sblock + block);
if (!bh) {
block++;
continue;
}
}
de = (struct bfs_dirent *)(bh->b_data + offset);
offset += BFS_DIRENT_SIZE;
if (le16_to_cpu(de->ino) &&
bfs_namecmp(namelen, name, de->name)) {
*res_dir = de;
return bh;
}
if (offset < bh->b_size)
continue;
brelse(bh);
bh = NULL;
offset = 0;
block++;
}
brelse(bh);
return NULL;
}