super.c

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/*
 *  linux/fs/super.c
 *
 *  Copyright (C) 1991, 1992  Linus Torvalds
 *
 *  super.c contains code to handle: - mount structures
 *                                   - super-block tables.
 *                                   - mount systemcall
 *                                   - umount systemcall
 *
 *  Added options to /proc/mounts
 *  Torbj鰎n Lindh ([e-mail]), April 14, 1996.
 *
 * GK 2/5/95  -  Changed to support mounting the root fs via NFS
 *
 *  Added kerneld support: Jacques Gelinas and Bjorn Ekwall
 *  Added change_root: Werner Almesberger & Hans Lermen, Feb '96
 */

#include <stdarg.h>

#include <linux/config.h>
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/mount.h>
#include <linux/malloc.h>
#include <linux/major.h>
#include <linux/stat.h>
#include <linux/errno.h>
#include <linux/string.h>
#include <linux/locks.h>
#include <linux/mm.h>
#include <linux/fd.h>

#include <asm/system.h>
#include <asm/segment.h>
#include <asm/bitops.h>

#ifdef CONFIG_KERNELD
#include <linux/kerneld.h>
#endif
 
#include <linux/nfs_fs.h>
#include <linux/nfs_fs_sb.h>
#include <linux/nfs_mount.h>

extern void wait_for_keypress(void);
extern struct file_operations * get_blkfops(unsigned int major);
extern void blkdev_release (struct inode *);

extern int root_mountflags;

static int do_remount_sb(struct super_block *sb, int flags, char * data);

/* this is initialized in init/main.c */
kdev_t ROOT_DEV;

struct super_block super_blocks[NR_SUPER];
static struct file_system_type *file_systems = (struct file_system_type *) NULL;
static struct vfsmount *vfsmntlist = (struct vfsmount *) NULL,
                       *vfsmnttail = (struct vfsmount *) NULL,
                       *mru_vfsmnt = (struct vfsmount *) NULL;

/* 
 * This part handles the management of the list of mounted filesystems.
 */
struct vfsmount *lookup_vfsmnt(kdev_t dev)
{
	struct vfsmount *lptr;

	if (vfsmntlist == (struct vfsmount *)NULL)
		return ((struct vfsmount *)NULL);

	if (mru_vfsmnt != (struct vfsmount *)NULL &&
	    mru_vfsmnt->mnt_dev == dev)
		return (mru_vfsmnt);

	for (lptr = vfsmntlist;
	     lptr != (struct vfsmount *)NULL;
	     lptr = lptr->mnt_next)
		if (lptr->mnt_dev == dev) {
			mru_vfsmnt = lptr;
			return (lptr);
		}

	return ((struct vfsmount *)NULL);
	/* NOTREACHED */
}

struct vfsmount *add_vfsmnt(kdev_t dev, const char *dev_name, const char *dir_name)
{
	struct vfsmount *lptr;
	char *tmp;

	lptr = (struct vfsmount *)kmalloc(sizeof(struct vfsmount), GFP_KERNEL);
        if (!lptr)
		return NULL;
	memset(lptr, 0, sizeof(struct vfsmount));

	lptr->mnt_dev = dev;
	lptr->mnt_sem.count = 1;
	if (dev_name && !getname(dev_name, &tmp)) {
		if ((lptr->mnt_devname =
		    (char *) kmalloc(strlen(tmp)+1, GFP_KERNEL)) != (char *)NULL)
			strcpy(lptr->mnt_devname, tmp);
		putname(tmp);
	}
	if (dir_name && !getname(dir_name, &tmp)) {
		if ((lptr->mnt_dirname =
		    (char *) kmalloc(strlen(tmp)+1, GFP_KERNEL)) != (char *)NULL)
			strcpy(lptr->mnt_dirname, tmp);
		putname(tmp);
	}

	if (vfsmntlist == (struct vfsmount *)NULL) {
		vfsmntlist = vfsmnttail = lptr;
	} else {
		vfsmnttail->mnt_next = lptr;
		vfsmnttail = lptr;
	}
	return (lptr);
}

void remove_vfsmnt(kdev_t dev)
{
	struct vfsmount *lptr, *tofree;

	if (vfsmntlist == (struct vfsmount *)NULL)
		return;
	lptr = vfsmntlist;
	if (lptr->mnt_dev == dev) {
		tofree = lptr;
		vfsmntlist = lptr->mnt_next;
		if (vfsmnttail->mnt_dev == dev)
			vfsmnttail = vfsmntlist;
	} else {
		while (lptr->mnt_next != (struct vfsmount *)NULL) {
			if (lptr->mnt_next->mnt_dev == dev)
				break;
			lptr = lptr->mnt_next;
		}
		tofree = lptr->mnt_next;
		if (tofree == (struct vfsmount *)NULL)
			return;
		lptr->mnt_next = lptr->mnt_next->mnt_next;
		if (vfsmnttail->mnt_dev == dev)
			vfsmnttail = lptr;
	}
	if (tofree == mru_vfsmnt)
		mru_vfsmnt = NULL;
	kfree(tofree->mnt_devname);
	kfree(tofree->mnt_dirname);
	kfree_s(tofree, sizeof(struct vfsmount));
}

int register_filesystem(struct file_system_type * fs)
{
        struct file_system_type ** tmp;

        if (!fs)
                return -EINVAL;
        if (fs->next)
                return -EBUSY;
        tmp = &file_systems;
        while (*tmp) {
                if (strcmp((*tmp)->name, fs->name) == 0)
                        return -EBUSY;
                tmp = &(*tmp)->next;
        }
        *tmp = fs;
        return 0;
}

#ifdef CONFIG_MODULES
int unregister_filesystem(struct file_system_type * fs)
{
	struct file_system_type ** tmp;

	tmp = &file_systems;
	while (*tmp) {
		if (fs == *tmp) {
			*tmp = fs->next;
			fs->next = NULL;
			return 0;
		}
		tmp = &(*tmp)->next;
	}
	return -EINVAL;
}
#endif

static int fs_index(const char * __name)
{
	struct file_system_type * tmp;
	char * name;
	int err, index;

	err = getname(__name, &name);
	if (err)
		return err;
	index = 0;
	for (tmp = file_systems ; tmp ; tmp = tmp->next) {
		if (strcmp(tmp->name, name) == 0) {
			putname(name);
			return index;
		}
		index++;
	}
	putname(name);
	return -EINVAL;
}

static int fs_name(unsigned int index, char * buf)
{
	struct file_system_type * tmp;
	int err, len;

	tmp = file_systems;
	while (tmp && index > 0) {
		tmp = tmp->next;
		index--;
	}
	if (!tmp)
		return -EINVAL;
	len = strlen(tmp->name) + 1;
	err = verify_area(VERIFY_WRITE, buf, len);
	if (err)
		return err;
	memcpy_tofs(buf, tmp->name, len);
	return 0;
}

static int fs_maxindex(void)
{
	struct file_system_type * tmp;
	int index;

	index = 0;
	for (tmp = file_systems ; tmp ; tmp = tmp->next)
		index++;
	return index;
}

/*
 * Whee.. Weird sysv syscall. 
 */
asmlinkage int sys_sysfs(int option, ...)
{
	va_list args;
	int retval = -EINVAL;
	unsigned int index;

	va_start(args, option);
	switch (option) {
		case 1:
			retval = fs_index(va_arg(args, const char *));
			break;

		case 2:
			index = va_arg(args, unsigned int);
			retval = fs_name(index, va_arg(args, char *));
			break;

		case 3:
			retval = fs_maxindex();
			break;
	}
	va_end(args);
	return retval;
}

static struct proc_fs_info {
	int flag;
	char *str;
} fs_info[] = {
	{ MS_NOEXEC, ",noexec" },
	{ MS_NOSUID, ",nosuid" },
	{ MS_NODEV, ",nodev" },
	{ MS_SYNCHRONOUS, ",sync" },
	{ MS_MANDLOCK, ",mand" },
	{ MS_NOATIME, ",noatime" },
#ifdef MS_NOSUB			/* Can't find this except in mount.c */
	{ MS_NOSUB, ",nosub" },
#endif
	{ 0, NULL }
};

static struct proc_nfs_info {
	int flag;
	char *str;
} nfs_info[] = {
	{ NFS_MOUNT_SOFT, ",soft" },
	{ NFS_MOUNT_INTR, ",intr" },
	{ NFS_MOUNT_POSIX, ",posix" },
	{ NFS_MOUNT_NOCTO, ",nocto" },
	{ NFS_MOUNT_NOAC, ",noac" },
	{ 0, NULL }
};

int get_filesystem_info( char *buf )
{
	struct vfsmount *tmp = vfsmntlist;
	struct proc_fs_info *fs_infop;
	struct proc_nfs_info *nfs_infop;
	struct nfs_server *nfss;
	int len = 0;

	while ( tmp && len < PAGE_SIZE - 160)
	{
		len += sprintf( buf + len, "%s %s %s %s",
			tmp->mnt_devname, tmp->mnt_dirname, tmp->mnt_sb->s_type->name,
			tmp->mnt_flags & MS_RDONLY ? "ro" : "rw" );
		for (fs_infop = fs_info; fs_infop->flag; fs_infop++) {
		  if (tmp->mnt_flags & fs_infop->flag) {
		    strcpy(buf + len, fs_infop->str);
		    len += strlen(fs_infop->str);
		  }
		}
		if (!strcmp("nfs", tmp->mnt_sb->s_type->name)) {
			nfss = &tmp->mnt_sb->u.nfs_sb.s_server;
			if (nfss->rsize != NFS_DEF_FILE_IO_BUFFER_SIZE) {
				len += sprintf(buf+len, ",rsize=%d",
					       nfss->rsize);
			}
			if (nfss->wsize != NFS_DEF_FILE_IO_BUFFER_SIZE) {
				len += sprintf(buf+len, ",wsize=%d",
					       nfss->wsize);
			}
			if (nfss->timeo != 7*HZ/10) {
				len += sprintf(buf+len, ",timeo=%d",
					       nfss->timeo*10/HZ);
			}
			if (nfss->retrans != 3) {
				len += sprintf(buf+len, ",retrans=%d",
					       nfss->retrans);
			}
			if (nfss->acregmin != 3*HZ) {
				len += sprintf(buf+len, ",acregmin=%d",
					       nfss->acregmin/HZ);
			}
			if (nfss->acregmax != 60*HZ) {
				len += sprintf(buf+len, ",acregmax=%d",
					       nfss->acregmax/HZ);
			}
			if (nfss->acdirmin != 30*HZ) {
				len += sprintf(buf+len, ",acdirmin=%d",
					       nfss->acdirmin/HZ);
			}
			if (nfss->acdirmax != 60*HZ) {
				len += sprintf(buf+len, ",acdirmax=%d",
					       nfss->acdirmax/HZ);
			}
			for (nfs_infop = nfs_info; nfs_infop->flag; nfs_infop++) {
				if (nfss->flags & nfs_infop->flag) {
					strcpy(buf + len, nfs_infop->str);
					len += strlen(nfs_infop->str);
				}
			}
			len += sprintf(buf+len, ",addr=%s",
				       nfss->hostname);
		}
		len += sprintf( buf + len, " 0 0\n" );
		tmp = tmp->mnt_next;
	}

	return len;
}

int get_filesystem_list(char * buf)
{
	int len = 0;
	struct file_system_type * tmp;

	tmp = file_systems;
	while (tmp && len < PAGE_SIZE - 80) {
		len += sprintf(buf+len, "%s\t%s\n",
			tmp->requires_dev ? "" : "nodev",
			tmp->name);
		tmp = tmp->next;
	}
	return len;
}

struct file_system_type *get_fs_type(const char *name)
{
	struct file_system_type * fs = file_systems;
	
	if (!name)
		return fs;
	for (fs = file_systems; fs && strcmp(fs->name, name); fs = fs->next)
		;
#ifdef CONFIG_KERNELD
	if (!fs && (request_module(name) == 0)) {
		for (fs = file_systems; fs && strcmp(fs->name, name); fs = fs->next)
			;
	}
#endif

	return fs;
}

void __wait_on_super(struct super_block * sb)
{
	struct wait_queue wait = { current, NULL };

	add_wait_queue(&sb->s_wait, &wait);
repeat:
	current->state = TASK_UNINTERRUPTIBLE;
	if (sb->s_lock) {
		schedule();
		goto repeat;
	}
	remove_wait_queue(&sb->s_wait, &wait);
	current->state = TASK_RUNNING;
}

void sync_supers(kdev_t dev)
{
	struct super_block * sb;

	for (sb = super_blocks + 0 ; sb < super_blocks + NR_SUPER ; sb++) {
		if (!sb->s_dev)
			continue;
		if (dev && sb->s_dev != dev)
			continue;
		wait_on_super(sb);
		if (!sb->s_dev || !sb->s_dirt)
			continue;
		if (dev && (dev != sb->s_dev))
			continue;
		if (sb->s_op && sb->s_op->write_super)
			sb->s_op->write_super(sb);
	}
}

static struct super_block * get_super(kdev_t dev)
{
	struct super_block * s;

	if (!dev)
		return NULL;
	s = 0+super_blocks;
	while (s < NR_SUPER+super_blocks)
		if (s->s_dev == dev) {
			wait_on_super(s);
			if (s->s_dev == dev)
				return s;
			s = 0+super_blocks;
		} else
			s++;
	return NULL;
}

void put_super(kdev_t dev)
{
	struct super_block * sb;

	if (dev == ROOT_DEV) {
		printk("VFS: Root device %s: prepare for armageddon\n",
		       kdevname(dev));
		return;
	}
	if (!(sb = get_super(dev)))
		return;
	if (sb->s_covered) {
		printk("VFS: Mounted device %s - tssk, tssk\n",
		       kdevname(dev));
		return;
	}
	if (sb->s_op && sb->s_op->put_super)
		sb->s_op->put_super(sb);
}

asmlinkage int sys_ustat(dev_t dev, struct ustat * ubuf)
{
        struct super_block *s;
        struct ustat tmp;
        struct statfs sbuf;
        unsigned long old_fs;
        int error;

        s = get_super(to_kdev_t(dev));
        if (s == NULL)
                return -EINVAL;

        if (!(s->s_op->statfs))
                return -ENOSYS;

        error = verify_area(VERIFY_WRITE,ubuf,sizeof(struct ustat));
        if (error)
                return error;

        old_fs = get_fs();
        set_fs(get_ds());
        s->s_op->statfs(s,&sbuf,sizeof(struct statfs));
        set_fs(old_fs);

        memset(&tmp,0,sizeof(struct ustat));
        tmp.f_tfree = sbuf.f_bfree;
        tmp.f_tinode = sbuf.f_ffree;

        memcpy_tofs(ubuf,&tmp,sizeof(struct ustat));
        return 0;
}

static struct super_block * read_super(kdev_t dev,const char *name,int flags,
				       void *data, int silent)
{
	struct super_block * s;
	struct file_system_type *type;

	if (!dev)
		return NULL;
	check_disk_change(dev);
	s = get_super(dev);
	if (s)
		return s;
	if (!(type = get_fs_type(name))) {
		printk("VFS: on device %s: get_fs_type(%s) failed\n",
		       kdevname(dev), name);
		return NULL;
	}
	for (s = 0+super_blocks ;; s++) {
		if (s >= NR_SUPER+super_blocks)
			return NULL;
		if (!(s->s_dev))
			break;
	}
	s->s_dev = dev;
	s->s_flags = flags;
	if (!type->read_super(s,data, silent)) {
		s->s_dev = 0;
		return NULL;
	}
	s->s_dev = dev;
	s->s_covered = NULL;
	s->s_rd_only = 0;
	s->s_dirt = 0;
	s->s_type = type;
	return s;
}

/*
 * Unnamed block devices are dummy devices used by virtual
 * filesystems which don't use real block-devices.  -- jrs
 */

static unsigned int unnamed_dev_in_use[256/(8*sizeof(unsigned int))] = { 0, };

kdev_t get_unnamed_dev(void)
{
	int i;

	for (i = 1; i < 256; i++) {
		if (!set_bit(i,unnamed_dev_in_use))