/* * 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 * Torbjörn Lindh (torbjorn.lindh@gopta.se), 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 * Added devfs support: Richard Gooch , 13-JAN-1998 */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #define __NO_VERSION__ #include /* * 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 DECLARE_MUTEX(mount_sem); extern void wait_for_keypress(void); 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; int nr_super_blocks = 0; int max_super_blocks = NR_SUPER; LIST_HEAD(super_blocks); /* * Handling of filesystem drivers list. * Rules: * Inclusion to/removals from/scanning of list are protected by spinlock. * During the unload module must call unregister_filesystem(). * We can access the fields of list element if: * 1) spinlock is held or * 2) we hold the reference to the module. * The latter can be guaranteed by call of try_inc_mod_count(); if it * returned 0 we must skip the element, otherwise we got the reference. * Once the reference is obtained we can drop the spinlock. */ static struct file_system_type *file_systems = NULL; static spinlock_t file_systems_lock = SPIN_LOCK_UNLOCKED; /* WARNING: This can be used only if we _already_ own a reference */ static void get_filesystem(struct file_system_type *fs) { if (fs->owner) __MOD_INC_USE_COUNT(fs->owner); } static void put_filesystem(struct file_system_type *fs) { if (fs->owner) __MOD_DEC_USE_COUNT(fs->owner); } static struct file_system_type **find_filesystem(const char *name) { struct file_system_type **p; for (p=&file_systems; *p; p=&(*p)->next) if (strcmp((*p)->name,name) == 0) break; return p; } /** * register_filesystem - register a new filesystem * @fs: the file system structure * * Adds the file system passed to the list of file systems the kernel * is aware of for mount and other syscalls. Returns 0 on success, * or a negative errno code on an error. * * The &struct file_system_type that is passed is linked into the kernel * structures and must not be freed until the file system has been * unregistered. */ int register_filesystem(struct file_system_type * fs) { int res = 0; struct file_system_type ** p; if (!fs) return -EINVAL; if (fs->next) return -EBUSY; spin_lock(&file_systems_lock); p = find_filesystem(fs->name); if (*p) res = -EBUSY; else *p = fs; spin_unlock(&file_systems_lock); return res; } /** * unregister_filesystem - unregister a file system * @fs: filesystem to unregister * * Remove a file system that was previously successfully registered * with the kernel. An error is returned if the file system is not found. * Zero is returned on a success. * * Once this function has returned the &struct file_system_type structure * may be freed or reused. */ int unregister_filesystem(struct file_system_type * fs) { struct file_system_type ** tmp; spin_lock(&file_systems_lock); tmp = &file_systems; while (*tmp) { if (fs == *tmp) { *tmp = fs->next; fs->next = NULL; spin_unlock(&file_systems_lock); return 0; } tmp = &(*tmp)->next; } spin_unlock(&file_systems_lock); return -EINVAL; } 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; err = -EINVAL; spin_lock(&file_systems_lock); for (tmp=file_systems, index=0 ; tmp ; tmp=tmp->next, index++) { if (strcmp(tmp->name,name) == 0) { err = index; break; } } spin_unlock(&file_systems_lock); putname(name); return err; } static int fs_name(unsigned int index, char * buf) { struct file_system_type * tmp; int len, res; spin_lock(&file_systems_lock); for (tmp = file_systems; tmp; tmp = tmp->next, index--) if (index <= 0 && try_inc_mod_count(tmp->owner)) break; spin_unlock(&file_systems_lock); if (!tmp) return -EINVAL; /* OK, we got the reference, so we can safely block */ len = strlen(tmp->name) + 1; res = copy_to_user(buf, tmp->name, len) ? -EFAULT : 0; put_filesystem(tmp); return res; } static int fs_maxindex(void) { struct file_system_type * tmp; int index; spin_lock(&file_systems_lock); for (tmp = file_systems, index = 0 ; tmp ; tmp = tmp->next, index++) ; spin_unlock(&file_systems_lock); return index; } /* * Whee.. Weird sysv syscall. */ asmlinkage long sys_sysfs(int option, unsigned long arg1, unsigned long arg2) { int retval = -EINVAL; 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; } return retval; } int get_filesystem_list(char * buf) { int len = 0; struct file_system_type * tmp; spin_lock(&file_systems_lock); 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; } spin_unlock(&file_systems_lock); return len; } static struct file_system_type *get_fs_type(const char *name) { struct file_system_type *fs; spin_lock(&file_systems_lock); fs = *(find_filesystem(name)); if (fs && !try_inc_mod_count(fs->owner)) fs = NULL; spin_unlock(&file_systems_lock); if (!fs && (request_module(name) == 0)) { spin_lock(&file_systems_lock); fs = *(find_filesystem(name)); if (fs && !try_inc_mod_count(fs->owner)) fs = NULL; spin_unlock(&file_systems_lock); } return fs; } static LIST_HEAD(vfsmntlist); static struct vfsmount *add_vfsmnt(struct super_block *sb, const char *dev_name, const char *dir_name) { struct vfsmount *mnt; char *name; mnt = (struct vfsmount *)kmalloc(sizeof(struct vfsmount), GFP_KERNEL); if (!mnt) goto out; memset(mnt, 0, sizeof(struct vfsmount)); mnt->mnt_sb = sb; mnt->mnt_dev = sb->s_dev; /* N.B. Is it really OK to have a vfsmount without names? */ if (dev_name) { name = (char *) kmalloc(strlen(dev_name)+1, GFP_KERNEL); if (name) { strcpy(name, dev_name); mnt->mnt_devname = name; } } if (dir_name) { name = (char *) kmalloc(strlen(dir_name)+1, GFP_KERNEL); if (name) { strcpy(name, dir_name); mnt->mnt_dirname = name; } } list_add(&mnt->mnt_list, vfsmntlist.prev); out: return mnt; } void remove_vfsmnt(kdev_t dev) { struct list_head *p, *next; for (p = vfsmntlist.next; p != &vfsmntlist; p = next) { struct vfsmount *mnt = list_entry(p, struct vfsmount, mnt_list); next = p->next; if (mnt->mnt_dev != dev) continue; list_del(&mnt->mnt_list); kfree(mnt->mnt_devname); kfree(mnt->mnt_dirname); kfree(mnt); } } 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; char *nostr; } nfs_info[] = { { NFS_MOUNT_SOFT, ",soft", ",hard" }, { NFS_MOUNT_INTR, ",intr", "" }, { NFS_MOUNT_POSIX, ",posix", "" }, { NFS_MOUNT_TCP, ",tcp", ",udp" }, { NFS_MOUNT_NOCTO, ",nocto", "" }, { NFS_MOUNT_NOAC, ",noac", "" }, { NFS_MOUNT_NONLM, ",nolock", ",lock" }, { 0, NULL, NULL } }; int get_filesystem_info( char *buf ) { struct list_head *p; struct proc_fs_info *fs_infop; struct proc_nfs_info *nfs_infop; struct nfs_server *nfss; int len = 0; char *path,*buffer = (char *) __get_free_page(GFP_KERNEL); if (!buffer) return 0; for (p = vfsmntlist.next; p!=&vfsmntlist && len < PAGE_SIZE - 160; p = p->next) { struct vfsmount *tmp = list_entry(p, struct vfsmount, mnt_list); if (!tmp->mnt_sb || !tmp->mnt_sb->s_root) continue; path = d_path(tmp->mnt_sb->s_root, tmp, buffer, PAGE_SIZE); if (!path) continue; len += sprintf( buf + len, "%s %s %s %s", tmp->mnt_devname, path, tmp->mnt_sb->s_type->name, tmp->mnt_sb->s_flags & MS_RDONLY ? "ro" : "rw" ); for (fs_infop = fs_info; fs_infop->flag; fs_infop++) { if (tmp->mnt_sb->s_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; len += sprintf(buf+len, ",v%d", nfss->rpc_ops->version); len += sprintf(buf+len, ",rsize=%d", nfss->rsize); 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++) { char *str; if (nfss->flags & nfs_infop->flag) str = nfs_infop->str; else str = nfs_infop->nostr; strcpy(buf + len, str); len += strlen(str); } len += sprintf(buf+len, ",addr=%s", nfss->hostname); } len += sprintf( buf + len, " 0 0\n" ); } free_page((unsigned long) buffer); return len; } /** * __wait_on_super - wait on a superblock * @sb: superblock to wait on * * Waits for a superblock to become unlocked and then returns. It does * not take the lock. This is an internal function. See wait_on_super(). */ void __wait_on_super(struct super_block * sb) { DECLARE_WAITQUEUE(wait, current); add_wait_queue(&sb->s_wait, &wait); repeat: set_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.) */ void sync_supers(kdev_t dev) { struct super_block * sb; for (sb = sb_entry(super_blocks.next); sb != sb_entry(&super_blocks); sb = sb_entry(sb->s_list.next)) { if (!sb->s_dev) continue; if (dev && sb->s_dev != dev) continue; if (!sb->s_dirt) continue; lock_super(sb); if (sb->s_dev && sb->s_dirt && (!dev || dev == sb->s_dev)) if (sb->s_op && sb->s_op->write_super) sb->s_op->write_super(sb); unlock_super(sb); } } /** * get_super - get the superblock of a device * @dev: device to get the superblock for * * Scans the superblock list and finds the superblock of the file system * mounted on the device given. %NULL is returned if no match is found. */ struct super_block * get_super(kdev_t dev) { struct super_block * s; if (!dev) return NULL; restart: s = sb_entry(super_blocks.next); while (s != sb_entry(&super_blocks)) if (s->s_dev == dev) { wait_on_super(s); if (s->s_dev == dev) return s; goto restart; } else s = sb_entry(s->s_list.next); return NULL; } asmlinkage long sys_ustat(dev_t dev, struct ustat * ubuf) { struct super_block *s; struct ustat tmp; struct statfs sbuf; int err = -EINVAL; lock_kernel(); s = get_super(to_kdev_t(dev)); if (s == NULL) goto out; err = vfs_statfs(s, &sbuf); if (err) goto out; memset(&tmp,0,sizeof(struct ustat)); tmp.f_tfree = sbuf.f_bfree; tmp.f_tinode = sbuf.f_ffree; err = copy_to_user(ubuf,&tmp,sizeof(struct ustat)) ? -EFAULT : 0; out: unlock_kernel(); return err; } /** * get_empty_super - find empty superblocks * * Find a superblock with no device assigned. A free superblock is * found and returned. If neccessary new superblocks are allocated. * %NULL is returned if there are insufficient resources to complete * the request. */ struct super_block *get_empty_super(void) { struct super_block *s; for (s = sb_entry(super_blocks.next); s != sb_entry(&super_blocks); s = sb_entry(s->s_list.next)) { if (s->s_dev) continue; if (!s->s_lock) return s; printk("VFS: empty superblock %p locked!\n", s); } /* Need a new one... */ if (nr_super_blocks >= max_super_blocks) return NULL; s = kmalloc(sizeof(struct super_block), GFP_USER); if (s) { nr_super_blocks++; memset(s, 0, sizeof(struct super_block)); INIT_LIST_HEAD(&s->s_dirty); list_add (&s->s_list, super_blocks.prev); init_waitqueue_head(&s->s_wait); INIT_LIST_HEAD(&s->s_files); } return s; } static struct super_block * read_super(kdev_t dev, struct block_device *bdev, struct file_system_type *type, int flags, void *data, int silent) { struct super_block * s; s = get_empty_super(); if (!s) goto out; s->s_dev = dev; s->s_bdev = bdev; s->s_flags = flags; s->s_dirt = 0; sema_init(&s->s_vfs_rename_sem,1); sema_init(&s->s_nfsd_free_path_sem,1); s->s_type = type; sema_init(&s->s_dquot.dqio_sem, 1); sema_init(&s->s_dquot.dqoff_sem, 1); s->s_dquot.flags = 0; lock_super(s); if (!type->read_super(s, data, silent)) goto out_fail; unlock_super(s); /* tell bdcache that we are going to keep this one */ if (bdev) atomic_inc(&bdev->bd_count); out: return s; out_fail: s->s_dev = 0; s->s_bdev = 0; s->s_type = NULL; unlock_super(s); return NULL; } /* * 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 (!test_and_set_bit(i,unnamed_dev_in_use)) return MKDEV(UNNAMED_MAJOR, i); } return 0; } void put_unnamed_dev(kdev_t dev) { if (!dev || MAJOR(dev) != UNNAMED_MAJOR) return; if (test_and_clear_bit(MINOR(dev), unnamed_dev_in_use)) return; printk("VFS: put_unnamed_dev: freeing unused device %s\n", kdevname(dev)); } static struct super_block *get_sb_bdev(struct file_system_type *fs_type, char *dev_name, int flags, void * data) { struct dentry *dentry; struct inode *inode; struct block_device *bdev; struct block_device_operations *bdops; struct super_block * sb; kdev_t dev; int error; /* What device it is? */ if (!dev_name || !*dev_name) return ERR_PTR(-EINVAL); dentry = lookup_dentry(dev_name, LOOKUP_FOLLOW|LOOKUP_POSITIVE); if (IS_ERR(dentry)) return (struct super_block *)dentry; inode = dentry->d_inode; error = -ENOTBLK; if (!S_ISBLK(inode->i_mode)) goto out; error = -EACCES; if (IS_NODEV(inode)) goto out; bdev = inode->i_bdev; bdops = devfs_get_ops ( devfs_get_handle_from_inode (inode) ); if (bdops) bdev->bd_op = bdops; /* Done with lookups, semaphore down */ down(&mount_sem); dev = to_kdev_t(bdev->bd_dev); check_disk_change(dev); error = -EACCES; if (!(flags & MS_RDONLY) && is_read_only(dev)) goto out; sb = get_super(dev); if (sb) { error = -EBUSY; goto out; /* MOUNT_REWRITE: the following should be used if (fs_type == sb->s_type) { dput(dentry); return sb; } */ } else { mode_t mode = FMODE_READ; /* we always need it ;-) */ if (!(flags & MS_RDONLY)) mode |= FMODE_WRITE; error = blkdev_get(bdev, mode, 0, BDEV_FS); if (error) goto out; error = -EINVAL; sb = read_super(dev, bdev, fs_type, flags, data, 0); if (sb) { get_filesystem(fs_type); dput(dentry); return sb; } blkdev_put(bdev, BDEV_FS); } out: dput(dentry); up(&mount_sem); return ERR_PTR(error); } static struct super_block *get_sb_nodev(struct file_system_type *fs_type, int flags, void * data) { kdev_t dev; int error = -EMFILE; down(&mount_sem); dev = get_unnamed_dev(); if (dev) { struct super_block * sb; error = -EINVAL; sb = read_super(dev, NULL, fs_type, flags, data, 0); if (sb) { get_filesystem(fs_type); return sb; } put_unnamed_dev(dev); } up(&mount_sem); return ERR_PTR(error); } static struct block_device *kill_super(struct super_block *sb, int umount_root) { struct block_device *bdev; kdev_t dev; lock_super(sb); if (sb->s_op) { if (sb->s_op->write_super && sb->s_dirt) sb->s_op->write_super(sb); if (sb->s_op->put_super) sb->s_op->put_super(sb); } /* Forget any remaining inodes */ if (invalidate_inodes(sb)) { printk("VFS: Busy inodes after unmount. " "Self-destruct in 5 seconds. Have a nice day...\n"); } dev = sb->s_dev; sb->s_dev = 0; /* Free the superblock */ bdev = sb->s_bdev; sb->s_bdev = NULL; put_filesystem(sb->s_type); sb->s_type = NULL; unlock_super(sb); if (umount_root) { /* special: the old device driver is going to be a ramdisk and the point of this call is to free its protected memory (even if dirty). */ destroy_buffers(dev); } if (bdev) { blkdev_put(bdev, BDEV_FS); bdput(bdev); } else put_unnamed_dev(dev); return bdev; } /* * Alters the mount flags of a mounted file system. Only the mount point * is used as a reference - file system type and the device are ignored. */ static int do_remount_sb(struct super_block *sb, int flags, char *data) { int retval; if (!(flags & MS_RDONLY) && sb->s_dev && is_read_only(sb->s_dev)) return -EACCES; /*flags |= MS_RDONLY;*/ /* If we are remounting RDONLY, make sure there are no rw files open */ if ((flags & MS_RDONLY) && !(sb->s_flags & MS_RDONLY)) if (!fs_may_remount_ro(sb)) return -EBUSY; if (sb->s_op && sb->s_op->remount_fs) { lock_super(sb); retval = sb->s_op->remount_fs(sb, &flags, data); unlock_super(sb); if (retval) return retval; } sb->s_flags = (sb->s_flags & ~MS_RMT_MASK) | (flags & MS_RMT_MASK); /* * We can't invalidate inodes as we can loose data when remounting * (someone might manage to alter data while we are waiting in lock_super() * or in foo_remount_fs())) */ return 0; } static int d_umount(struct super_block * sb) { struct dentry * root = sb->s_root; struct dentry * covered = root->d_covers; if (root->d_count != 1) return -EBUSY; if (root->d_inode->i_state) return -EBUSY; sb->s_root = NULL; if (covered != root) { root->d_covers = root; covered->d_mounts = covered; dput(covered); } dput(root); return 0; } static void d_mount(struct dentry *covered, struct dentry *dentry) { if (covered->d_mounts != covered) { printk("VFS: mount - already mounted\n"); return; } covered->d_mounts = dentry; dentry->d_covers = covered; } static struct block_device *do_umount(kdev_t dev, int unmount_root, int flags) { struct super_block * sb; struct block_device *bdev; int retval; retval = -ENOENT; sb = get_super(dev); if (!sb || !sb->s_root) goto out; /* * Before checking whether the filesystem is still busy, * make sure the kernel doesn't hold any quota files open * on the device. If the umount fails, too bad -- there * are no quotas running any more. Just turn them on again. */ DQUOT_OFF(sb); acct_auto_close(dev); /* * If we may have to abort operations to get out of this * mount, and they will themselves hold resources we must * allow the fs to do things. In the Unix tradition of * 'Gee thats tricky lets do it in userspace' the umount_begin * might fail to complete on the first run through as other tasks * must return, and the like. Thats for the mount program to worry * about for the moment. */ if( (flags&MNT_FORCE) && sb->s_op->umount_begin) sb->s_op->umount_begin(sb); /* * Shrink dcache, then fsync. This guarantees that if the * filesystem is quiescent at this point, then (a) only the * root entry should be in use and (b) that root entry is * clean. */ shrink_dcache_sb(sb); fsync_dev(dev); if (sb == current->fs->root->d_sb && !unmount_root) { /* * Special case for "unmounting" root ... * we just try to remount it readonly. */ retval = 0; if (!(sb->s_flags & MS_RDONLY)) retval = do_remount_sb(sb, MS_RDONLY, 0); return ERR_PTR(retval); } retval = d_umount(sb); if (retval) goto out; remove_vfsmnt(dev); bdev = kill_super(sb, unmount_root); return bdev; out: return ERR_PTR(retval); } static int umount_dev(kdev_t dev, int flags) { int retval; struct block_device *bdev; retval = -ENXIO; if (MAJOR(dev) >= MAX_BLKDEV) goto out; fsync_dev(dev); down(&mount_sem); bdev = do_umount(dev, 0, flags); if (IS_ERR(bdev)) retval = PTR_ERR(bdev); else retval = 0; up(&mount_sem); out: return retval; } /* * Now umount can handle mount points as well as block devices. * This is important for filesystems which use unnamed block devices. * * We now support a flag for forced unmount like the other 'big iron' * unixes. Our API is identical to OSF/1 to avoid making a mess of AMD */ asmlinkage long sys_umount(char * name, int flags) { struct dentry * dentry; int retval; if (!capable(CAP_SYS_ADMIN)) return -EPERM; lock_kernel(); dentry = namei(name); retval = PTR_ERR(dentry); if (!IS_ERR(dentry)) { struct inode * inode = dentry->d_inode; kdev_t dev = inode->i_rdev; retval = 0; if (S_ISBLK(inode->i_mode)) { if (IS_NODEV(inode)) retval = -EACCES; } else { struct super_block *sb = inode->i_sb; retval = -EINVAL; if (sb && inode == sb->s_root->d_inode) { dev = sb->s_dev; retval = 0; } } dput(dentry); if (!retval) retval = umount_dev(dev, flags); } unlock_kernel(); return retval; } /* * The 2.0 compatible umount. No flags. */ asmlinkage long sys_oldumount(char * name) { return sys_umount(name,0); } /* * Check whether we can mount the specified device. */ int fs_may_mount(kdev_t dev) { struct super_block * sb = get_super(dev); int busy; busy = sb && sb->s_root && (sb->s_root->d_count != 1 || sb->s_root->d_covers != sb->s_root); return !busy; } /* * change filesystem flags. dir should be a physical root of filesystem. * If you've mounted a non-root directory somewhere and want to do remount * on it - tough luck. */ static int do_remount(const char *dir,int flags,char *data) { struct dentry *dentry; int retval; if (!capable(CAP_SYS_ADMIN)) return -EPERM; dentry = lookup_dentry(dir, LOOKUP_FOLLOW|LOOKUP_POSITIVE); retval = PTR_ERR(dentry); if (!IS_ERR(dentry)) { struct super_block * sb = dentry->d_inode->i_sb; retval = -ENODEV; if (sb) { retval = -EINVAL; if (dentry == sb->s_root) { /* * Shrink the dcache and sync the device. */ shrink_dcache_sb(sb); fsync_dev(sb->s_dev); if (flags & MS_RDONLY) acct_auto_close(sb->s_dev); retval = do_remount_sb(sb, flags, data); } } dput(dentry); } return retval; } static int copy_mount_options (const void * data, unsigned long *where) { int i; unsigned long page; struct vm_area_struct * vma; *where = 0; if (!data) return 0; vma = find_vma(current->mm, (unsigned long) data); if (!vma || (unsigned long) data < vma->vm_start) return -EFAULT; if (!(vma->vm_flags & VM_READ)) return -EFAULT; i = vma->vm_end - (unsigned long) data; if (PAGE_SIZE <= (unsigned long) i) i = PAGE_SIZE-1; if (!(page = __get_free_page(GFP_KERNEL))) { return -ENOMEM; } if (copy_from_user((void *) page,data,i)) { free_page(page); return -EFAULT; } *where = page; return 0; } /* * Flags is a 16-bit value that allows up to 16 non-fs dependent flags to * be given to the mount() call (ie: read-only, no-dev, no-suid etc). * * data is a (void *) that can point to any structure up to * PAGE_SIZE-1 bytes, which can contain arbitrary fs-dependent * information (or be NULL). * * NOTE! As old versions of mount() didn't use this setup, the flags * have to have a special 16-bit magic number in the high word: * 0xC0ED. If this magic word isn't present, the flags and data info * aren't used, as the syscall assumes we are talking to an older * version that didn't understand them. */ long do_sys_mount(char * dev_name, char * dir_name, char *type_page, unsigned long new_flags, void *data_page) { struct file_system_type * fstype; struct dentry * dir_d; struct vfsmount *mnt; struct super_block *sb; int retval; unsigned long flags = 0; /* Basic sanity checks */ if (!dir_name || !*dir_name || !memchr(dir_name, 0, PAGE_SIZE)) return -EINVAL; if (!type_page || !memchr(type_page, 0, PAGE_SIZE)) return -EINVAL; if (dev_name && !memchr(dev_name, 0, PAGE_SIZE)) return -EINVAL; /* OK, looks good, now let's see what do they want */ /* just change the flags? - capabilities are checked in do_remount() */ if ((new_flags & (MS_MGC_MSK|MS_REMOUNT)) == (MS_MGC_VAL|MS_REMOUNT)) return do_remount(dir_name, new_flags&~(MS_MGC_MSK|MS_REMOUNT), (char *) data_page); if ((new_flags & MS_MGC_MSK) == MS_MGC_VAL) flags = new_flags & ~MS_MGC_MSK; /* loopback mount? This is special - requires fewer capabilities */ /* MOUNT_REWRITE: ... and is yet to be merged */ /* for the rest we _really_ need capabilities... */ if (!capable(CAP_SYS_ADMIN)) return -EPERM; /* ... filesystem driver... */ fstype = get_fs_type(type_page); if (!fstype) return -ENODEV; /* ... and mountpoint. Do the lookup first to force automounting. */ dir_d = lookup_dentry(dir_name, LOOKUP_FOLLOW|LOOKUP_POSITIVE); retval = PTR_ERR(dir_d); if (IS_ERR(dir_d)) goto fs_out; /* get superblock, locks mount_sem on success */ if (fstype->fs_flags & FS_REQUIRES_DEV) sb = get_sb_bdev(fstype, dev_name,flags, data_page); else sb = get_sb_nodev(fstype, flags, data_page); retval = PTR_ERR(sb); if (IS_ERR(sb)) goto dput_out; retval = -ENOENT; if (d_unhashed(dir_d)) goto fail; retval = -ENOTDIR; if (!S_ISDIR(dir_d->d_inode->i_mode)) goto fail; retval = -EBUSY; if (dir_d->d_covers != dir_d) goto fail; /* * We may have slept while reading the super block, * so we check afterwards whether it's safe to mount. */ retval = -EBUSY; if (!fs_may_mount(sb->s_dev)) goto fail; retval = -ENOMEM; mnt = add_vfsmnt(sb, dev_name, dir_name); if (!mnt) goto fail; d_mount(dget(dir_d), sb->s_root); retval = 0; unlock_out: up(&mount_sem); dput_out: dput(dir_d); fs_out: put_filesystem(fstype); return retval; fail: dput(sb->s_root); sb->s_root = NULL; kill_super(sb, 0); goto unlock_out; } asmlinkage long sys_mount(char * dev_name, char * dir_name, char * type, unsigned long new_flags, void * data) { int retval; unsigned long data_page = 0; unsigned long type_page = 0; unsigned long dev_page = 0; char *dir_page; lock_kernel(); retval = copy_mount_options (type, &type_page); if (retval < 0) goto out; /* copy_mount_options allows a NULL user pointer, * and just returns zero in that case. But if we * allow the type to be NULL we will crash. * Previously we did not check this case. */ if (type_page == 0) { retval = -EINVAL; goto out; } dir_page = getname(dir_name); retval = PTR_ERR(dir_page); if (IS_ERR(dir_page)) goto out1; retval = copy_mount_options (dev_name, &dev_page); if (retval < 0) goto out2; retval = copy_mount_options (data, &data_page); if (retval >= 0) { retval = do_sys_mount((char*)dev_page,dir_page,(char*)type_page, new_flags, (void*)data_page); free_page(data_page); } free_page(dev_page); out2: putname(dir_page); out1: free_page(type_page); out: unlock_kernel(); return retval; } void __init mount_root(void) { struct file_system_type * fs_type; struct super_block * sb; struct vfsmount *vfsmnt = NULL; struct block_device *bdev = NULL; mode_t mode; int retval; void *handle; char path[64]; int path_start = -1; #ifdef CONFIG_ROOT_NFS void *data; if (MAJOR(ROOT_DEV) != UNNAMED_MAJOR) goto skip_nfs; fs_type = get_fs_type("nfs"); if (!fs_type) goto no_nfs; ROOT_DEV = get_unnamed_dev(); if (!ROOT_DEV) /* * Your /linuxrc sucks worse than MSExchange - that's the * only way you could run out of anon devices at that point. */ goto no_anon; data = nfs_root_data(); if (!data) goto no_server; sb = read_super(ROOT_DEV, NULL, fs_type, root_mountflags, data, 1); if (sb) /* * We _can_ fail there, but if that will happen we have no * chance anyway (no memory for vfsmnt and we _will_ need it, * no matter which fs we try to mount). */ goto mount_it; no_server: put_unnamed_dev(ROOT_DEV); no_anon: put_filesystem(fs_type); no_nfs: printk(KERN_ERR "VFS: Unable to mount root fs via NFS, trying floppy.\n"); ROOT_DEV = MKDEV(FLOPPY_MAJOR, 0); skip_nfs: #endif #ifdef CONFIG_BLK_DEV_FD if (MAJOR(ROOT_DEV) == FLOPPY_MAJOR) { #ifdef CONFIG_BLK_DEV_RAM extern int rd_doload; extern void rd_load_secondary(void); #endif floppy_eject(); #ifndef CONFIG_BLK_DEV_RAM printk(KERN_NOTICE "(Warning, this kernel has no ramdisk support)\n"); #else /* rd_doload is 2 for a dual initrd/ramload setup */ if(rd_doload==2) rd_load_secondary(); else #endif { printk(KERN_NOTICE "VFS: Insert root floppy and press ENTER\n"); wait_for_keypress(); } } #endif devfs_make_root (root_device_name); handle = devfs_find_handle (NULL, ROOT_DEVICE_NAME, 0, MAJOR (ROOT_DEV), MINOR (ROOT_DEV), DEVFS_SPECIAL_BLK, 1); if (handle) /* Sigh: bd*() functions only paper over the cracks */ { unsigned major, minor; devfs_get_maj_min (handle, &major, &minor); ROOT_DEV = MKDEV (major, minor); } /* * Probably pure paranoia, but I'm less than happy about delving into * devfs crap and checking it right now. Later. */ if (!ROOT_DEV) panic("I have no root and I want to scream"); bdev = bdget(kdev_t_to_nr(ROOT_DEV)); if (!bdev) panic(__FUNCTION__ ": unable to allocate root device"); bdev->bd_op = devfs_get_ops (handle); path_start = devfs_generate_path (handle, path + 5, sizeof (path) - 5); mode = FMODE_READ; if (!(root_mountflags & MS_RDONLY)) mode |= FMODE_WRITE; retval = blkdev_get(bdev, mode, 0, BDEV_FS); if (retval == -EROFS) { root_mountflags |= MS_RDONLY; retval = blkdev_get(bdev, FMODE_READ, 0, BDEV_FS); } if (retval) { /* * Allow the user to distinguish between failed open * and bad superblock on root device. */ printk ("VFS: Cannot open root device \"%s\" or %s\n", root_device_name, kdevname (ROOT_DEV)); printk ("Please append a correct \"root=\" boot option\n"); panic("VFS: Unable to mount root fs on %s", kdevname(ROOT_DEV)); } check_disk_change(ROOT_DEV); spin_lock(&file_systems_lock); for (fs_type = file_systems ; fs_type ; fs_type = fs_type->next) { if (!(fs_type->fs_flags & FS_REQUIRES_DEV)) continue; if (!try_inc_mod_count(fs_type->owner)) continue; spin_unlock(&file_systems_lock); sb = get_super(ROOT_DEV); if (sb) { /* Shouldn't we fail here? Oh, well... */ sb->s_bdev = bdev; goto mount_it; } sb = read_super(ROOT_DEV,bdev,fs_type,root_mountflags,NULL,1); if (sb) goto mount_it; spin_lock(&file_systems_lock); put_filesystem(fs_type); } spin_unlock(&file_systems_lock); panic("VFS: Unable to mount root fs on %s", kdevname(ROOT_DEV)); mount_it: set_fs_root(current->fs, vfsmnt, sb->s_root); set_fs_pwd(current->fs, vfsmnt, sb->s_root); printk ("VFS: Mounted root (%s filesystem)%s.\n", fs_type->name, (sb->s_flags & MS_RDONLY) ? " readonly" : ""); if (path_start >= 0) { devfs_mk_symlink (NULL, "root", 0, DEVFS_FL_DEFAULT, path + 5 + path_start, 0, NULL, NULL); memcpy (path + path_start, "/dev/", 5); vfsmnt = add_vfsmnt (sb, path + path_start, "/"); } else vfsmnt = add_vfsmnt (sb, "/dev/root", "/"); if (vfsmnt) { if (bdev) bdput(bdev); /* sb holds a reference */ return; } panic("VFS: add_vfsmnt failed for root fs"); } static void chroot_fs_refs(struct dentry *old_root, struct vfsmount *old_rootmnt, struct dentry *new_root, struct vfsmount *new_rootmnt) { struct task_struct *p; /* We can't afford dput() blocking under the tasklist_lock */ mntget(old_rootmnt); dget(old_root); read_lock(&tasklist_lock); for_each_task(p) { if (!p->fs) continue; if (p->fs->root == old_root && p->fs->rootmnt == old_rootmnt) set_fs_root(p->fs, new_rootmnt, new_root); if (p->fs->pwd == old_root && p->fs->pwdmnt == old_rootmnt) set_fs_pwd(p->fs, new_rootmnt, new_root); } read_unlock(&tasklist_lock); dput(old_root); mntput(old_rootmnt); } /* * Moves the current root to put_root, and sets root/cwd of all processes * which had them on the old root to new_root. * * Note: * - we don't move root/cwd if they are not at the root (reason: if something * cared enough to change them, it's probably wrong to force them elsewhere) * - it's okay to pick a root that isn't the root of a file system, e.g. * /nfs/my_root where /nfs is the mount point. Better avoid creating * unreachable mount points this way, though. */ asmlinkage long sys_pivot_root(const char *new_root, const char *put_old) { struct dentry *root = current->fs->root; struct vfsmount *root_mnt = current->fs->rootmnt; struct dentry *d_new_root, *d_put_old, *covered; struct dentry *root_dev_root, *new_root_dev_root; struct dentry *walk, *next; struct vfsmount *new_root_mnt = NULL; int error; if (!capable(CAP_SYS_ADMIN)) return -EPERM; lock_kernel(); d_new_root = namei(new_root); if (IS_ERR(d_new_root)) { error = PTR_ERR(d_new_root); goto out0; } d_put_old = namei(put_old); if (IS_ERR(d_put_old)) { error = PTR_ERR(d_put_old); goto out1; } down(&mount_sem); if (!d_new_root->d_inode || !d_put_old->d_inode) { error = -ENOENT; goto out2; } if (!S_ISDIR(d_new_root->d_inode->i_mode) || !S_ISDIR(d_put_old->d_inode->i_mode)) { error = -ENOTDIR; goto out2; } error = -EBUSY; if (d_new_root->d_sb == root->d_sb || d_put_old->d_sb == root->d_sb) goto out2; /* loop */ if (d_put_old != d_put_old->d_covers) goto out2; /* mount point is busy */ error = -EINVAL; walk = d_put_old; /* make sure we can reach put_old from new_root */ for (;;) { next = walk->d_covers->d_parent; if (next == walk) goto out2; if (next == d_new_root) break; walk = next; } new_root_dev_root = d_new_root->d_sb->s_root; covered = new_root_dev_root->d_covers; new_root_dev_root->d_covers = new_root_dev_root; dput(covered); covered->d_mounts = covered; root_dev_root = root->d_sb->s_root; root_dev_root->d_covers = dget(d_put_old); d_put_old->d_mounts = root_dev_root; chroot_fs_refs(root,root_mnt,d_new_root,new_root_mnt); error = 0; out2: up(&mount_sem); dput(d_put_old); out1: dput(d_new_root); out0: unlock_kernel(); return error; } #ifdef CONFIG_BLK_DEV_INITRD int __init change_root(kdev_t new_root_dev,const char *put_old) { kdev_t old_root_dev; struct vfsmount *vfsmnt; struct dentry *old_root,*old_pwd,*dir_d = NULL; int error; old_root = current->fs->root; old_pwd = current->fs->pwd; old_root_dev = ROOT_DEV; if (!fs_may_mount(new_root_dev)) { printk(KERN_CRIT "New root is busy. Staying in initrd.\n"); return -EBUSY; } /* First unmount devfs if mounted */ dir_d = lookup_dentry ("/dev", LOOKUP_FOLLOW|LOOKUP_POSITIVE); if (!IS_ERR(dir_d)) { struct super_block *sb = dir_d->d_inode->i_sb; if (sb && (dir_d->d_inode == sb->s_root->d_inode) && (sb->s_magic == DEVFS_SUPER_MAGIC)) { dput (dir_d); do_umount (sb->s_dev, 0, 0); } else dput (dir_d); } ROOT_DEV = new_root_dev; mount_root(); dput(old_root); dput(old_pwd); #if 1 shrink_dcache(); printk("change_root: old root has d_count=%d\n", old_root->d_count); #endif mount_devfs_fs (); /* * Get the new mount directory */ dir_d = lookup_dentry(put_old, LOOKUP_FOLLOW|LOOKUP_POSITIVE); if (IS_ERR(dir_d)) { error = PTR_ERR(dir_d); } else { error = 0; } if (!error && dir_d->d_covers != dir_d) { dput(dir_d); error = -EBUSY; } if (!error && !S_ISDIR(dir_d->d_inode->i_mode)) { dput(dir_d); error = -ENOTDIR; } if (error) { struct block_device *bdev; printk(KERN_NOTICE "Trying to unmount old root ... "); bdev = do_umount(old_root_dev,1, 0); if (!IS_ERR(bdev)) { printk("okay\n"); return 0; } printk(KERN_ERR "error %ld\n",PTR_ERR(bdev)); return error; } remove_vfsmnt(old_root_dev); vfsmnt = add_vfsmnt(old_root->d_sb, "/dev/root.old", put_old); if (vfsmnt) { d_mount(dir_d,old_root); return 0; } printk(KERN_CRIT "Trouble: add_vfsmnt failed\n"); return -ENOMEM; } #endif