[PATCH] VFS: Permit filesystem to perform statfs with a known root dentry

[deliverable/linux.git] / fs / qnx4 / inode.c

/*
 * QNX4 file system, Linux implementation.
 *
 * Version : 0.2.1
 *
 * Using parts of the xiafs filesystem.
 *
 * History :
 *
 * 01-06-1998 by Richard Frowijn : first release.
 * 20-06-1998 by Frank Denis : Linux 2.1.99+ support, boot signature, misc.
 * 30-06-1998 by Frank Denis : first step to write inodes.
 */

#include <linux/config.h>
#include <linux/module.h>
#include <linux/types.h>
#include <linux/string.h>
#include <linux/errno.h>
#include <linux/slab.h>
#include <linux/fs.h>
#include <linux/qnx4_fs.h>
#include <linux/init.h>
#include <linux/highuid.h>
#include <linux/smp_lock.h>
#include <linux/pagemap.h>
#include <linux/buffer_head.h>
#include <linux/vfs.h>
#include <asm/uaccess.h>

#define QNX4_VERSION  4
#define QNX4_BMNAME   ".bitmap"

static struct super_operations qnx4_sops;

#ifdef CONFIG_QNX4FS_RW

int qnx4_sync_inode(struct inode *inode)
{
	int err = 0;
# if 0
	struct buffer_head *bh;

   	bh = qnx4_update_inode(inode);
	if (bh && buffer_dirty(bh))
	{
		sync_dirty_buffer(bh);
		if (buffer_req(bh) && !buffer_uptodate(bh))
		{
			printk ("IO error syncing qnx4 inode [%s:%08lx]\n",
				inode->i_sb->s_id, inode->i_ino);
			err = -1;
		}
	        brelse (bh);
	} else if (!bh) {
		err = -1;
	}
# endif

	return err;
}

static void qnx4_delete_inode(struct inode *inode)
{
	QNX4DEBUG(("qnx4: deleting inode [%lu]\n", (unsigned long) inode->i_ino));
	truncate_inode_pages(&inode->i_data, 0);
	inode->i_size = 0;
	qnx4_truncate(inode);
	lock_kernel();
	qnx4_free_inode(inode);
	unlock_kernel();
}

static void qnx4_write_super(struct super_block *sb)
{
	lock_kernel();
	QNX4DEBUG(("qnx4: write_super\n"));
	sb->s_dirt = 0;
	unlock_kernel();
}

static int qnx4_write_inode(struct inode *inode, int unused)
{
	struct qnx4_inode_entry *raw_inode;
	int block, ino;
	struct buffer_head *bh;
	ino = inode->i_ino;

	QNX4DEBUG(("qnx4: write inode 1.\n"));
	if (inode->i_nlink == 0) {
		return 0;
	}
	if (!ino) {
		printk("qnx4: bad inode number on dev %s: %d is out of range\n",
		       inode->i_sb->s_id, ino);
		return -EIO;
	}
	QNX4DEBUG(("qnx4: write inode 2.\n"));
	block = ino / QNX4_INODES_PER_BLOCK;
	lock_kernel();
	if (!(bh = sb_bread(inode->i_sb, block))) {
		printk("qnx4: major problem: unable to read inode from dev "
		       "%s\n", inode->i_sb->s_id);
		unlock_kernel();
		return -EIO;
	}
	raw_inode = ((struct qnx4_inode_entry *) bh->b_data) +
	    (ino % QNX4_INODES_PER_BLOCK);
	raw_inode->di_mode  = cpu_to_le16(inode->i_mode);
	raw_inode->di_uid   = cpu_to_le16(fs_high2lowuid(inode->i_uid));
	raw_inode->di_gid   = cpu_to_le16(fs_high2lowgid(inode->i_gid));
	raw_inode->di_nlink = cpu_to_le16(inode->i_nlink);
	raw_inode->di_size  = cpu_to_le32(inode->i_size);
	raw_inode->di_mtime = cpu_to_le32(inode->i_mtime.tv_sec);
	raw_inode->di_atime = cpu_to_le32(inode->i_atime.tv_sec);
	raw_inode->di_ctime = cpu_to_le32(inode->i_ctime.tv_sec);
	raw_inode->di_first_xtnt.xtnt_size = cpu_to_le32(inode->i_blocks);
	mark_buffer_dirty(bh);
	brelse(bh);
	unlock_kernel();
	return 0;
}

#endif

static void qnx4_put_super(struct super_block *sb);
static struct inode *qnx4_alloc_inode(struct super_block *sb);
static void qnx4_destroy_inode(struct inode *inode);
static void qnx4_read_inode(struct inode *);
static int qnx4_remount(struct super_block *sb, int *flags, char *data);
static int qnx4_statfs(struct dentry *, struct kstatfs *);

static struct super_operations qnx4_sops =
{
	.alloc_inode	= qnx4_alloc_inode,
	.destroy_inode	= qnx4_destroy_inode,
	.read_inode	= qnx4_read_inode,
	.put_super	= qnx4_put_super,
	.statfs		= qnx4_statfs,
	.remount_fs	= qnx4_remount,
#ifdef CONFIG_QNX4FS_RW
	.write_inode	= qnx4_write_inode,
	.delete_inode	= qnx4_delete_inode,
	.write_super	= qnx4_write_super,
#endif
};

static int qnx4_remount(struct super_block *sb, int *flags, char *data)
{
	struct qnx4_sb_info *qs;

	qs = qnx4_sb(sb);
	qs->Version = QNX4_VERSION;
#ifndef CONFIG_QNX4FS_RW
	*flags |= MS_RDONLY;
#endif
	if (*flags & MS_RDONLY) {
		return 0;
	}

	mark_buffer_dirty(qs->sb_buf);

	return 0;
}

static struct buffer_head *qnx4_getblk(struct inode *inode, int nr,
				       int create)
{
	struct buffer_head *result = NULL;

	if ( nr >= 0 )
		nr = qnx4_block_map( inode, nr );
	if (nr) {
		result = sb_getblk(inode->i_sb, nr);
		return result;
	}
	if (!create) {
		return NULL;
	}
#if 0
	tmp = qnx4_new_block(inode->i_sb);
	if (!tmp) {
		return NULL;
	}
	result = sb_getblk(inode->i_sb, tmp);
	if (tst) {
		qnx4_free_block(inode->i_sb, tmp);
		brelse(result);
		goto repeat;
	}
	tst = tmp;
#endif
	inode->i_ctime = CURRENT_TIME_SEC;
	mark_inode_dirty(inode);
	return result;
}

struct buffer_head *qnx4_bread(struct inode *inode, int block, int create)
{
	struct buffer_head *bh;

	bh = qnx4_getblk(inode, block, create);
	if (!bh || buffer_uptodate(bh)) {
		return bh;
	}
	ll_rw_block(READ, 1, &bh);
	wait_on_buffer(bh);
	if (buffer_uptodate(bh)) {
		return bh;
	}
	brelse(bh);

	return NULL;
}

static int qnx4_get_block( struct inode *inode, sector_t iblock, struct buffer_head *bh, int create )
{
	unsigned long phys;

	QNX4DEBUG(("qnx4: qnx4_get_block inode=[%ld] iblock=[%ld]\n",inode->i_ino,iblock));

	phys = qnx4_block_map( inode, iblock );
	if ( phys ) {
		// logical block is before EOF
		map_bh(bh, inode->i_sb, phys);
	} else if ( create ) {
		// to be done.
	}
	return 0;
}

unsigned long qnx4_block_map( struct inode *inode, long iblock )
{
	int ix;
	long offset, i_xblk;
	unsigned long block = 0;
	struct buffer_head *bh = NULL;
	struct qnx4_xblk *xblk = NULL;
	struct qnx4_inode_entry *qnx4_inode = qnx4_raw_inode(inode);
	u16 nxtnt = le16_to_cpu(qnx4_inode->di_num_xtnts);

	if ( iblock < le32_to_cpu(qnx4_inode->di_first_xtnt.xtnt_size) ) {
		// iblock is in the first extent. This is easy.
		block = le32_to_cpu(qnx4_inode->di_first_xtnt.xtnt_blk) + iblock - 1;
	} else {
		// iblock is beyond first extent. We have to follow the extent chain.
		i_xblk = le32_to_cpu(qnx4_inode->di_xblk);
		offset = iblock - le32_to_cpu(qnx4_inode->di_first_xtnt.xtnt_size);
		ix = 0;
		while ( --nxtnt > 0 ) {
			if ( ix == 0 ) {
				// read next xtnt block.
				bh = sb_bread(inode->i_sb, i_xblk - 1);
				if ( !bh ) {
					QNX4DEBUG(("qnx4: I/O error reading xtnt block [%ld])\n", i_xblk - 1));
					return -EIO;
				}
				xblk = (struct qnx4_xblk*)bh->b_data;
				if ( memcmp( xblk->xblk_signature, "IamXblk", 7 ) ) {
					QNX4DEBUG(("qnx4: block at %ld is not a valid xtnt\n", qnx4_inode->i_xblk));
					return -EIO;
				}
			}
			if ( offset < le32_to_cpu(xblk->xblk_xtnts[ix].xtnt_size) ) {
				// got it!
				block = le32_to_cpu(xblk->xblk_xtnts[ix].xtnt_blk) + offset - 1;
				break;
			}
			offset -= le32_to_cpu(xblk->xblk_xtnts[ix].xtnt_size);
			if ( ++ix >= xblk->xblk_num_xtnts ) {
				i_xblk = le32_to_cpu(xblk->xblk_next_xblk);
				ix = 0;
				brelse( bh );
				bh = NULL;
			}
		}
		if ( bh )
			brelse( bh );
	}

	QNX4DEBUG(("qnx4: mapping block %ld of inode %ld = %ld\n",iblock,inode->i_ino,block));
	return block;
}

static int qnx4_statfs(struct dentry *dentry, struct kstatfs *buf)
{
	struct super_block *sb = dentry->d_sb;

	lock_kernel();

	buf->f_type    = sb->s_magic;
	buf->f_bsize   = sb->s_blocksize;
	buf->f_blocks  = le32_to_cpu(qnx4_sb(sb)->BitMap->di_size) * 8;
	buf->f_bfree   = qnx4_count_free_blocks(sb);
	buf->f_bavail  = buf->f_bfree;
	buf->f_namelen = QNX4_NAME_MAX;

	unlock_kernel();

	return 0;
}

/*
 * Check the root directory of the filesystem to make sure
 * it really _is_ a qnx4 filesystem, and to check the size
 * of the directory entry.
 */
static const char *qnx4_checkroot(struct super_block *sb)
{
	struct buffer_head *bh;
	struct qnx4_inode_entry *rootdir;
	int rd, rl;
	int i, j;
	int found = 0;

	if (*(qnx4_sb(sb)->sb->RootDir.di_fname) != '/') {
		return "no qnx4 filesystem (no root dir).";
	} else {
		QNX4DEBUG(("QNX4 filesystem found on dev %s.\n", sb->s_id));
		rd = le32_to_cpu(qnx4_sb(sb)->sb->RootDir.di_first_xtnt.xtnt_blk) - 1;
		rl = le32_to_cpu(qnx4_sb(sb)->sb->RootDir.di_first_xtnt.xtnt_size);
		for (j = 0; j < rl; j++) {
			bh = sb_bread(sb, rd + j);	/* root dir, first block */
			if (bh == NULL) {
				return "unable to read root entry.";
			}
			for (i = 0; i < QNX4_INODES_PER_BLOCK; i++) {
				rootdir = (struct qnx4_inode_entry *) (bh->b_data + i * QNX4_DIR_ENTRY_SIZE);
				if (rootdir->di_fname != NULL) {
					QNX4DEBUG(("Rootdir entry found : [%s]\n", rootdir->di_fname));
					if (!strncmp(rootdir->di_fname, QNX4_BMNAME, sizeof QNX4_BMNAME)) {
						found = 1;
						qnx4_sb(sb)->BitMap = kmalloc( sizeof( struct qnx4_inode_entry ), GFP_KERNEL );
						if (!qnx4_sb(sb)->BitMap) {
							brelse (bh);
							return "not enough memory for bitmap inode";
						}
						memcpy( qnx4_sb(sb)->BitMap, rootdir, sizeof( struct qnx4_inode_entry ) );	/* keep bitmap inode known */
						break;
					}
				}
			}
			brelse(bh);
			if (found != 0) {
				break;
			}
		}
		if (found == 0) {
			return "bitmap file not found.";
		}
	}
	return NULL;
}

static int qnx4_fill_super(struct super_block *s, void *data, int silent)
{
	struct buffer_head *bh;
	struct inode *root;
	const char *errmsg;
	struct qnx4_sb_info *qs;

	qs = kmalloc(sizeof(struct qnx4_sb_info), GFP_KERNEL);
	if (!qs)
		return -ENOMEM;
	s->s_fs_info = qs;
	memset(qs, 0, sizeof(struct qnx4_sb_info));

	sb_set_blocksize(s, QNX4_BLOCK_SIZE);

	/* Check the superblock signature. Since the qnx4 code is
	   dangerous, we should leave as quickly as possible
	   if we don't belong here... */
	bh = sb_bread(s, 1);
	if (!bh) {
		printk("qnx4: unable to read the superblock\n");
		goto outnobh;
	}
	if ( le32_to_cpup((__le32*) bh->b_data) != QNX4_SUPER_MAGIC ) {
		if (!silent)
			printk("qnx4: wrong fsid in superblock.\n");
		goto out;
	}
	s->s_op = &qnx4_sops;
	s->s_magic = QNX4_SUPER_MAGIC;
#ifndef CONFIG_QNX4FS_RW
	s->s_flags |= MS_RDONLY;	/* Yup, read-only yet */
#endif
	qnx4_sb(s)->sb_buf = bh;
	qnx4_sb(s)->sb = (struct qnx4_super_block *) bh->b_data;


 	/* check before allocating dentries, inodes, .. */
	errmsg = qnx4_checkroot(s);
	if (errmsg != NULL) {
 		if (!silent)
 			printk("qnx4: %s\n", errmsg);
		goto out;
	}

 	/* does root not have inode number QNX4_ROOT_INO ?? */
 	root = iget(s, QNX4_ROOT_INO * QNX4_INODES_PER_BLOCK);
 	if (!root) {
 		printk("qnx4: get inode failed\n");
 		goto out;
 	}

 	s->s_root = d_alloc_root(root);
 	if (s->s_root == NULL)
 		goto outi;

	brelse(bh);

	return 0;

      outi:
	iput(root);
      out:
	brelse(bh);
      outnobh:
	kfree(qs);
	s->s_fs_info = NULL;
	return -EINVAL;
}

static void qnx4_put_super(struct super_block *sb)
{
	struct qnx4_sb_info *qs = qnx4_sb(sb);
	kfree( qs->BitMap );
	kfree( qs );
	sb->s_fs_info = NULL;
	return;
}

static int qnx4_writepage(struct page *page, struct writeback_control *wbc)
{
	return block_write_full_page(page,qnx4_get_block, wbc);
}
static int qnx4_readpage(struct file *file, struct page *page)
{
	return block_read_full_page(page,qnx4_get_block);
}
static int qnx4_prepare_write(struct file *file, struct page *page,
			      unsigned from, unsigned to)
{
	struct qnx4_inode_info *qnx4_inode = qnx4_i(page->mapping->host);
	return cont_prepare_write(page, from, to, qnx4_get_block,
				  &qnx4_inode->mmu_private);
}
static sector_t qnx4_bmap(struct address_space *mapping, sector_t block)
{
	return generic_block_bmap(mapping,block,qnx4_get_block);
}
static struct address_space_operations qnx4_aops = {
	.readpage	= qnx4_readpage,
	.writepage	= qnx4_writepage,
	.sync_page	= block_sync_page,
	.prepare_write	= qnx4_prepare_write,
	.commit_write	= generic_commit_write,
	.bmap		= qnx4_bmap
};

static void qnx4_read_inode(struct inode *inode)
{
	struct buffer_head *bh;
	struct qnx4_inode_entry *raw_inode;
	int block, ino;
	struct super_block *sb = inode->i_sb;
	struct qnx4_inode_entry *qnx4_inode = qnx4_raw_inode(inode);

	ino = inode->i_ino;
	inode->i_mode = 0;

	QNX4DEBUG(("Reading inode : [%d]\n", ino));
	if (!ino) {
		printk("qnx4: bad inode number on dev %s: %d is out of range\n",
		       sb->s_id, ino);
		return;
	}
	block = ino / QNX4_INODES_PER_BLOCK;

	if (!(bh = sb_bread(sb, block))) {
		printk("qnx4: major problem: unable to read inode from dev "
		       "%s\n", sb->s_id);
		return;
	}
	raw_inode = ((struct qnx4_inode_entry *) bh->b_data) +
	    (ino % QNX4_INODES_PER_BLOCK);

	inode->i_mode    = le16_to_cpu(raw_inode->di_mode);
	inode->i_uid     = (uid_t)le16_to_cpu(raw_inode->di_uid);
	inode->i_gid     = (gid_t)le16_to_cpu(raw_inode->di_gid);
	inode->i_nlink   = le16_to_cpu(raw_inode->di_nlink);
	inode->i_size    = le32_to_cpu(raw_inode->di_size);
	inode->i_mtime.tv_sec   = le32_to_cpu(raw_inode->di_mtime);
	inode->i_mtime.tv_nsec = 0;
	inode->i_atime.tv_sec   = le32_to_cpu(raw_inode->di_atime);
	inode->i_atime.tv_nsec = 0;
	inode->i_ctime.tv_sec   = le32_to_cpu(raw_inode->di_ctime);
	inode->i_ctime.tv_nsec = 0;
	inode->i_blocks  = le32_to_cpu(raw_inode->di_first_xtnt.xtnt_size);
	inode->i_blksize = QNX4_DIR_ENTRY_SIZE;

	memcpy(qnx4_inode, raw_inode, QNX4_DIR_ENTRY_SIZE);
	if (S_ISREG(inode->i_mode)) {
		inode->i_op = &qnx4_file_inode_operations;
		inode->i_fop = &qnx4_file_operations;
		inode->i_mapping->a_ops = &qnx4_aops;
		qnx4_i(inode)->mmu_private = inode->i_size;
	} else if (S_ISDIR(inode->i_mode)) {
		inode->i_op = &qnx4_dir_inode_operations;
		inode->i_fop = &qnx4_dir_operations;
	} else if (S_ISLNK(inode->i_mode)) {
		inode->i_op = &page_symlink_inode_operations;
		inode->i_mapping->a_ops = &qnx4_aops;
		qnx4_i(inode)->mmu_private = inode->i_size;
	} else
		printk("qnx4: bad inode %d on dev %s\n",ino,sb->s_id);
	brelse(bh);
}

static kmem_cache_t *qnx4_inode_cachep;

static struct inode *qnx4_alloc_inode(struct super_block *sb)
{
	struct qnx4_inode_info *ei;
	ei = kmem_cache_alloc(qnx4_inode_cachep, SLAB_KERNEL);
	if (!ei)
		return NULL;
	return &ei->vfs_inode;
}

static void qnx4_destroy_inode(struct inode *inode)
{
	kmem_cache_free(qnx4_inode_cachep, qnx4_i(inode));
}

static void init_once(void *foo, kmem_cache_t * cachep,
		      unsigned long flags)
{
	struct qnx4_inode_info *ei = (struct qnx4_inode_info *) foo;

	if ((flags & (SLAB_CTOR_VERIFY | SLAB_CTOR_CONSTRUCTOR)) ==
	    SLAB_CTOR_CONSTRUCTOR)
		inode_init_once(&ei->vfs_inode);
}

static int init_inodecache(void)
{
	qnx4_inode_cachep = kmem_cache_create("qnx4_inode_cache",
					     sizeof(struct qnx4_inode_info),
					     0, (SLAB_RECLAIM_ACCOUNT|
						SLAB_MEM_SPREAD),
					     init_once, NULL);
	if (qnx4_inode_cachep == NULL)
		return -ENOMEM;
	return 0;
}

static void destroy_inodecache(void)
{
	if (kmem_cache_destroy(qnx4_inode_cachep))
		printk(KERN_INFO
		       "qnx4_inode_cache: not all structures were freed\n");
}

static int qnx4_get_sb(struct file_system_type *fs_type,
	int flags, const char *dev_name, void *data, struct vfsmount *mnt)
{
	return get_sb_bdev(fs_type, flags, dev_name, data, qnx4_fill_super,
			   mnt);
}

static struct file_system_type qnx4_fs_type = {
	.owner		= THIS_MODULE,
	.name		= "qnx4",
	.get_sb		= qnx4_get_sb,
	.kill_sb	= kill_block_super,
	.fs_flags	= FS_REQUIRES_DEV,
};

static int __init init_qnx4_fs(void)
{
	int err;

	err = init_inodecache();
	if (err)
		return err;

	err = register_filesystem(&qnx4_fs_type);
	if (err) {
		destroy_inodecache();
		return err;
	}

	printk("QNX4 filesystem 0.2.3 registered.\n");
	return 0;
}

static void __exit exit_qnx4_fs(void)
{
	unregister_filesystem(&qnx4_fs_type);
	destroy_inodecache();
}

module_init(init_qnx4_fs)
module_exit(exit_qnx4_fs)
MODULE_LICENSE("GPL");