super.c

来自「基于组件方式开发操作系统的OSKIT源代码」· C语言 代码 · 共 1,342 行 · 第 1/3 页

/*
 *  linux/fs/super.c
 *
 *  Copyright (C) 1991, 1992  Linus Torvalds
 *
 *  super.c contains code to handle: - mount structures
 *                                   - super-block tables.
 *                                   - mount system call
 *                                   - umount system call
 *
 *  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
 *
 *  OSKit support added by the University of Utah, 1997
 */

#include <linux/config.h>
#include <linux/malloc.h>
#include <linux/locks.h>
#include <linux/smp_lock.h>
#ifndef OSKIT
#include <linux/fd.h>
#endif /* OSKIT */
#include <linux/init.h>
#include <linux/quotaops.h>
#include <linux/acct.h>

#include <asm/uaccess.h>

#ifndef OSKIT
#include <linux/nfs_fs.h>
#include <linux/nfs_fs_sb.h>
#include <linux/nfs_mount.h>
#endif /* OSKIT */

#ifdef CONFIG_KMOD
#include <linux/kmod.h>
#endif

/*
 * We use a semaphore to synchronize all mount/umount
 * activity - imagine the mess if we have a race between
 * unmounting a filesystem and re-mounting it (or something
 * else).
 */
static struct semaphore mount_sem = MUTEX;

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

extern int root_mountflags;
extern void rd_load_secondary(void);

#ifndef OSKIT
static int do_remount_sb(struct super_block *sb, int flags, char * data);
#endif

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

int nr_super_blocks = 0;
int max_super_blocks = NR_SUPER;
LIST_HEAD(super_blocks);

static struct file_system_type *file_systems = (struct file_system_type *) NULL;
#ifndef OSKIT
struct vfsmount *vfsmntlist = (struct vfsmount *) NULL;
static struct vfsmount *vfsmnttail = (struct vfsmount *) NULL,
                       *mru_vfsmnt = (struct vfsmount *) NULL;
#endif /* OSKIT */

#ifndef OSKIT
/* 
 * 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 */
}

static struct vfsmount *add_vfsmnt(struct super_block *sb,
			const char *dev_name, const char *dir_name)
{
	struct vfsmount *lptr;
	char *tmp, *name;

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

	lptr->mnt_sb = sb;
	lptr->mnt_dev = sb->s_dev;
	lptr->mnt_flags = sb->s_flags;

	sema_init(&lptr->mnt_dquot.dqio_sem, 1);
	sema_init(&lptr->mnt_dquot.dqoff_sem, 1);
	lptr->mnt_dquot.flags = 0;

	/* N.B. Is it really OK to have a vfsmount without names? */
	if (dev_name && !IS_ERR(tmp = getname(dev_name))) {
		name = (char *) kmalloc(strlen(tmp)+1, GFP_KERNEL);
		if (name) {
			strcpy(name, tmp);
			lptr->mnt_devname = name;
		}
		putname(tmp);
	}
	if (dir_name && !IS_ERR(tmp = getname(dir_name))) {
		name = (char *) kmalloc(strlen(tmp)+1, GFP_KERNEL);
		if (name) {
			strcpy(name, tmp);
			lptr->mnt_dirname = name;
		}
		putname(tmp);
	}

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

static 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));
}
#endif /* OSKIT */

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;
}

#ifndef OSKIT
#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;

	name = getname(__name);
	err = PTR_ERR(name);
	if (IS_ERR(name))
		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 len;

	tmp = file_systems;
	while (tmp && index > 0) {
		tmp = tmp->next;
		index--;
	}
	if (!tmp)
		return -EINVAL;
	len = strlen(tmp->name) + 1;
	return copy_to_user(buf, tmp->name, len) ? -EFAULT : 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, unsigned long arg1, unsigned long arg2)
{
	int retval = -EINVAL;

	lock_kernel();
	switch (option) {
		case 1:
			retval = fs_index((const char *) arg1);
			break;

		case 2:
			retval = fs_name(arg1, (char *) arg2);
			break;

		case 3:
			retval = fs_maxindex();
			break;
	}
	unlock_kernel();
	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" },
	{ MS_NODIRATIME, ",nodiratime" },
#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 0
			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);
			}
#endif
			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->fs_flags & FS_REQUIRES_DEV) ? "" : "nodev",
			tmp->name);
		tmp = tmp->next;
	}
	return len;
}
#endif /* OSKIT */

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_KMOD
	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;
}

/*
 * Note: check the dirty flag before waiting, so we don't
 * hold up the sync while mounting a device. (The newly
 * mounted device won't need syncing.)