/*

* linux/fs/super.c

*

* Copyright (C) 1991, 1992 Linus Torvalds

*

* super.c contains code to handle: - mount structures

* - super-block tables

* - filesystem drivers list

* - mount system call

* - umount system call

* - ustat system call

*

* 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 options to /proc/mounts:

* Torbjörn Lindh (torbjorn.lindh@gopta.se), April 14, 1996.

* Added devfs support: Richard Gooch <rgooch@atnf.csiro.au>, 13-JAN-1998

* Heavily rewritten for 'one fs - one tree' dcache architecture. AV, Mar 2000

*/

#include <linux/module.h>

#include <linux/slab.h>

#include <linux/acct.h>

#include <linux/blkdev.h>

#include <linux/mount.h>

#include <linux/security.h>

#include <linux/writeback.h> /* for the emergency remount stuff */

#include <linux/idr.h>

#include <linux/mutex.h>

#include <linux/backing-dev.h>

#include <linux/rculist_bl.h>

#include <linux/cleancache.h>

#include "internal.h"

LIST_HEAD(super_blocks);

DEFINE_SPINLOCK(sb_lock);

/**

* alloc_super - create new superblock

* @type: filesystem type superblock should belong to

*

* Allocates and initializes a new &struct super_block. alloc_super()

* returns a pointer new superblock or %NULL if allocation had failed.

*/

static struct super_block *alloc_super(struct file_system_type *type)

{

struct super_block *s = kzalloc(sizeof(struct super_block), GFP_USER);

static const struct super_operations default_op;

if (s) {

if (security_sb_alloc(s)) {

kfree(s);

s = NULL;

goto out;

}

#ifdef CONFIG_SMP

s->s_files = alloc_percpu(struct list_head);

if (!s->s_files) {

security_sb_free(s);

kfree(s);

s = NULL;

goto out;

} else {

int i;

for_each_possible_cpu(i)

INIT_LIST_HEAD(per_cpu_ptr(s->s_files, i));

}

#else

INIT_LIST_HEAD(&s->s_files);

#endif

s->s_bdi = &default_backing_dev_info;

INIT_LIST_HEAD(&s->s_instances);

INIT_HLIST_BL_HEAD(&s->s_anon);

INIT_LIST_HEAD(&s->s_inodes);

INIT_LIST_HEAD(&s->s_dentry_lru);

init_rwsem(&s->s_umount);

mutex_init(&s->s_lock);

lockdep_set_class(&s->s_umount, &type->s_umount_key);

/*

* The locking rules for s_lock are up to the

* filesystem. For example ext3fs has different

* lock ordering than usbfs:

*/

lockdep_set_class(&s->s_lock, &type->s_lock_key);

/*

* sget() can have s_umount recursion.

*

* When it cannot find a suitable sb, it allocates a new

* one (this one), and tries again to find a suitable old

* one.

*

* In case that succeeds, it will acquire the s_umount

* lock of the old one. Since these are clearly distrinct

* locks, and this object isn't exposed yet, there's no

* risk of deadlocks.

*

* Annotate this by putting this lock in a different

* subclass.

*/

down_write_nested(&s->s_umount, SINGLE_DEPTH_NESTING);

s->s_count = 1;

atomic_set(&s->s_active, 1);

mutex_init(&s->s_vfs_rename_mutex);

lockdep_set_class(&s->s_vfs_rename_mutex, &type->s_vfs_rename_key);

mutex_init(&s->s_dquot.dqio_mutex);

mutex_init(&s->s_dquot.dqonoff_mutex);

init_rwsem(&s->s_dquot.dqptr_sem);

init_waitqueue_head(&s->s_wait_unfrozen);

s->s_maxbytes = MAX_NON_LFS;

s->s_op = &default_op;

s->s_time_gran = 1000000000;

s->cleancache_poolid = -1;

}

out:

return s;

}

/**

* destroy_super - frees a superblock

* @s: superblock to free

*

* Frees a superblock.

*/

static inline void destroy_super(struct super_block *s)

{

#ifdef CONFIG_SMP

free_percpu(s->s_files);

#endif

security_sb_free(s);

kfree(s->s_subtype);

kfree(s->s_options);

kfree(s);

}

/* Superblock refcounting */

/*

* Drop a superblock's refcount. The caller must hold sb_lock.

*/

void __put_super(struct super_block *sb)

{

if (!--sb->s_count) {

list_del_init(&sb->s_list);

destroy_super(sb);

}

}

/**

* put_super - drop a temporary reference to superblock

* @sb: superblock in question

*

* Drops a temporary reference, frees superblock if there's no

* references left.

*/

void put_super(struct super_block *sb)

{

spin_lock(&sb_lock);

__put_super(sb);

spin_unlock(&sb_lock);

}

/**

* deactivate_locked_super - drop an active reference to superblock

* @s: superblock to deactivate

*

* Drops an active reference to superblock, converting it into a temprory

* one if there is no other active references left. In that case we

* tell fs driver to shut it down and drop the temporary reference we

* had just acquired.

*

* Caller holds exclusive lock on superblock; that lock is released.

*/

void deactivate_locked_super(struct super_block *s)

{

struct file_system_type *fs = s->s_type;

if (atomic_dec_and_test(&s->s_active)) {

cleancache_flush_fs(s);

fs->kill_sb(s);

/*

* We need to call rcu_barrier so all the delayed rcu free

* inodes are flushed before we release the fs module.

*/

rcu_barrier();

put_filesystem(fs);

put_super(s);

} else {

up_write(&s->s_umount);

}

}

EXPORT_SYMBOL(deactivate_locked_super);

/**

* deactivate_super - drop an active reference to superblock

* @s: superblock to deactivate

*

* Variant of deactivate_locked_super(), except that superblock is *not*

* locked by caller. If we are going to drop the final active reference,

* lock will be acquired prior to that.

*/

void deactivate_super(struct super_block *s)

{

if (!atomic_add_unless(&s->s_active, -1, 1)) {

down_write(&s->s_umount);

deactivate_locked_super(s);

}

}

EXPORT_SYMBOL(deactivate_super);

/**

* grab_super - acquire an active reference

* @s: reference we are trying to make active

*

* Tries to acquire an active reference. grab_super() is used when we

* had just found a superblock in super_blocks or fs_type->fs_supers

* and want to turn it into a full-blown active reference. grab_super()

* is called with sb_lock held and drops it. Returns 1 in case of

* success, 0 if we had failed (superblock contents was already dead or

* dying when grab_super() had been called).

*/

static int grab_super(struct super_block *s) __releases(sb_lock)

{

if (atomic_inc_not_zero(&s->s_active)) {

spin_unlock(&sb_lock);

return 1;

}

/* it's going away */

s->s_count++;

spin_unlock(&sb_lock);

/* wait for it to die */

down_write(&s->s_umount);

up_write(&s->s_umount);

put_super(s);

return 0;

}

/*

* Superblock locking. We really ought to get rid of these two.

*/

void lock_super(struct super_block * sb)

{

get_fs_excl();

mutex_lock(&sb->s_lock);

}

void unlock_super(struct super_block * sb)

{

put_fs_excl();

mutex_unlock(&sb->s_lock);

}

EXPORT_SYMBOL(lock_super);

EXPORT_SYMBOL(unlock_super);

/**

* generic_shutdown_super - common helper for ->kill_sb()

* @sb: superblock to kill

*

* generic_shutdown_super() does all fs-independent work on superblock

* shutdown. Typical ->kill_sb() should pick all fs-specific objects

* that need destruction out of superblock, call generic_shutdown_super()

* and release aforementioned objects. Note: dentries and inodes _are_

* taken care of and do not need specific handling.

*

* Upon calling this function, the filesystem may no longer alter or

* rearrange the set of dentries belonging to this super_block, nor may it

* change the attachments of dentries to inodes.

*/

void generic_shutdown_super(struct super_block *sb)

{

const struct super_operations *sop = sb->s_op;

if (sb->s_root) {

shrink_dcache_for_umount(sb);

sync_filesystem(sb);

get_fs_excl();

sb->s_flags &= ~MS_ACTIVE;

fsnotify_unmount_inodes(&sb->s_inodes);

evict_inodes(sb);

if (sop->put_super)

sop->put_super(sb);

if (!list_empty(&sb->s_inodes)) {

printk("VFS: Busy inodes after unmount of %s. "

"Self-destruct in 5 seconds. Have a nice day...\n",

sb->s_id);

}

put_fs_excl();

}

spin_lock(&sb_lock);

/* should be initialized for __put_super_and_need_restart() */

list_del_init(&sb->s_instances);

spin_unlock(&sb_lock);

up_write(&sb->s_umount);

}

EXPORT_SYMBOL(generic_shutdown_super);

/**

* sget - find or create a superblock

* @type: filesystem type superblock should belong to

* @test: comparison callback

* @set: setup callback

* @data: argument to each of them

*/

struct super_block *sget(struct file_system_type *type,

int (*test)(struct super_block *,void *),

int (*set)(struct super_block *,void *),

void *data)

{

struct super_block *s = NULL;

struct super_block *old;

int err;

retry:

spin_lock(&sb_lock);

if (test) {

list_for_each_entry(old, &type->fs_supers, s_instances) {

if (!test(old, data))

continue;

if (!grab_super(old))

goto retry;

if (s) {

up_write(&s->s_umount);

destroy_super(s);

s = NULL;

}

down_write(&old->s_umount);

if (unlikely(!(old->s_flags & MS_BORN))) {

deactivate_locked_super(old);

goto retry;

}

return old;

}

}

if (!s) {

spin_unlock(&sb_lock);

s = alloc_super(type);

if (!s)

return ERR_PTR(-ENOMEM);

goto retry;

}

err = set(s, data);

if (err) {

spin_unlock(&sb_lock);

up_write(&s->s_umount);

destroy_super(s);

return ERR_PTR(err);

}

s->s_type = type;

strlcpy(s->s_id, type->name, sizeof(s->s_id));

list_add_tail(&s->s_list, &super_blocks);

list_add(&s->s_instances, &type->fs_supers);

spin_unlock(&sb_lock);

get_filesystem(type);

return s;

}

EXPORT_SYMBOL(sget);

void drop_super(struct super_block *sb)

{

up_read(&sb->s_umount);

put_super(sb);

}

EXPORT_SYMBOL(drop_super);

/**

* sync_supers - helper for periodic superblock writeback

*

* Call the write_super method if present on all dirty superblocks in

* the system. This is for the periodic writeback used by most older

* filesystems. For data integrity superblock writeback use

* sync_filesystems() instead.

*

* 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(void)

{

struct super_block *sb, *p = NULL;

spin_lock(&sb_lock);

list_for_each_entry(sb, &super_blocks, s_list) {

if (list_empty(&sb->s_instances))

continue;

if (sb->s_op->write_super && sb->s_dirt) {

sb->s_count++;

spin_unlock(&sb_lock);

down_read(&sb->s_umount);

if (sb->s_root && sb->s_dirt)

sb->s_op->write_super(sb);

up_read(&sb->s_umount);

spin_lock(&sb_lock);

if (p)

__put_super(p);

p = sb;

}

}

if (p)

__put_super(p);

spin_unlock(&sb_lock);

}

/**

* iterate_supers - call function for all active superblocks

* @f: function to call

* @arg: argument to pass to it

*

* Scans the superblock list and calls given function, passing it

* locked superblock and given argument.

*/

void iterate_supers(void (*f)(struct super_block *, void *), void *arg)

{

struct super_block *sb, *p = NULL;

spin_lock(&sb_lock);

list_for_each_entry(sb, &super_blocks, s_list) {

if (list_empty(&sb->s_instances))

continue;

sb->s_count++;

spin_unlock(&sb_lock);

down_read(&sb->s_umount);

if (sb->s_root)

f(sb, arg);

up_read(&sb->s_umount);

spin_lock(&sb_lock);

if (p)

__put_super(p);

p = sb;

}

if (p)

__put_super(p);

spin_unlock(&sb_lock);

}

/**

* get_super - get the superblock of a device

* @bdev: 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(struct block_device *bdev)

{

struct super_block *sb;

if (!bdev)

return NULL;

spin_lock(&sb_lock);

rescan:

list_for_each_entry(sb, &super_blocks, s_list) {

if (list_empty(&sb->s_instances))

continue;

if (sb->s_bdev == bdev) {

sb->s_count++;

spin_unlock(&sb_lock);

down_read(&sb->s_umount);

/* still alive? */

if (sb->s_root)

return sb;

up_read(&sb->s_umount);

/* nope, got unmounted */

spin_lock(&sb_lock);

__put_super(sb);

goto rescan;

}

}

spin_unlock(&sb_lock);

return NULL;

}

EXPORT_SYMBOL(get_super);

/**

* get_active_super - get an active reference to the superblock of a device

* @bdev: device to get the superblock for

*

* Scans the superblock list and finds the superblock of the file system

* mounted on the device given. Returns the superblock with an active

* reference or %NULL if none was found.

*/

struct super_block *get_active_super(struct block_device *bdev)

{

struct super_block *sb;

if (!bdev)

return NULL;

restart:

spin_lock(&sb_lock);

list_for_each_entry(sb, &super_blocks, s_list) {

if (list_empty(&sb->s_instances))

continue;

if (sb->s_bdev == bdev) {

if (grab_super(sb)) /* drops sb_lock */

return sb;

else

goto restart;

}

}

spin_unlock(&sb_lock);

return NULL;

}

struct super_block *user_get_super(dev_t dev)

{

struct super_block *sb;

spin_lock(&sb_lock);

rescan:

list_for_each_entry(sb, &super_blocks, s_list) {

if (list_empty(&sb->s_instances))

continue;

if (sb->s_dev == dev) {

sb->s_count++;

spin_unlock(&sb_lock);

down_read(&sb->s_umount);

/* still alive? */

if (sb->s_root)

return sb;

up_read(&sb->s_umount);

/* nope, got unmounted */

spin_lock(&sb_lock);

__put_super(sb);

goto rescan;

}

}

spin_unlock(&sb_lock);

return NULL;

}

/**

* do_remount_sb - asks filesystem to change mount options.

* @sb: superblock in question

* @flags: numeric part of options

* @data: the rest of options

* @force: whether or not to force the change

*

* Alters the mount options of a mounted file system.

*/

int do_remount_sb(struct super_block *sb, int flags, void *data, int force)

{

int retval;

int remount_ro;

if (sb->s_frozen != SB_UNFROZEN)

return -EBUSY;

#ifdef CONFIG_BLOCK

if (!(flags & MS_RDONLY) && bdev_read_only(sb->s_bdev))

return -EACCES;

#endif

if (flags & MS_RDONLY)

acct_auto_close(sb);

shrink_dcache_sb(sb);

sync_filesystem(sb);

remount_ro = (flags & MS_RDONLY) && !(sb->s_flags & MS_RDONLY);

/* If we are remounting RDONLY and current sb is read/write,

make sure there are no rw files opened */

if (remount_ro) {

if (force)

mark_files_ro(sb);

else if (!fs_may_remount_ro(sb))

return -EBUSY;

}

if (sb->s_op->remount_fs) {

retval = sb->s_op->remount_fs(sb, &flags, data);

if (retval)

return retval;

}

sb->s_flags = (sb->s_flags & ~MS_RMT_MASK) | (flags & MS_RMT_MASK);

/*

* Some filesystems modify their metadata via some other path than the

* bdev buffer cache (eg. use a private mapping, or directories in

* pagecache, etc). Also file data modifications go via their own

* mappings. So If we try to mount readonly then copy the filesystem

* from bdev, we could get stale data, so invalidate it to give a best

* effort at coherency.

*/

if (remount_ro && sb->s_bdev)

invalidate_bdev(sb->s_bdev);

return 0;

}

static void do_emergency_remount(struct work_struct *work)

{

struct super_block *sb, *p = NULL;

spin_lock(&sb_lock);

list_for_each_entry(sb, &super_blocks, s_list) {

if (list_empty(&sb->s_instances))

continue;

sb->s_count++;

spin_unlock(&sb_lock);

down_write(&sb->s_umount);

if (sb->s_root && sb->s_bdev && !(sb->s_flags & MS_RDONLY)) {

/*

* What lock protects sb->s_flags??

*/

do_remount_sb(sb, MS_RDONLY, NULL, 1);

}

up_write(&sb->s_umount);

spin_lock(&sb_lock);

if (p)

__put_super(p);

p = sb;

}

if (p)

__put_super(p);

spin_unlock(&sb_lock);

kfree(work);

printk("Emergency Remount complete\n");

}

void emergency_remount(void)

{

struct work_struct *work;

work = kmalloc(sizeof(*work), GFP_ATOMIC);

if (work) {

INIT_WORK(work, do_emergency_remount);

schedule_work(work);

}

}

/*

* Unnamed block devices are dummy devices used by virtual

* filesystems which don't use real block-devices. -- jrs

*/

static DEFINE_IDA(unnamed_dev_ida);

static DEFINE_SPINLOCK(unnamed_dev_lock);/* protects the above */

static int unnamed_dev_start = 0; /* don't bother trying below it */

int set_anon_super(struct super_block *s, void *data)

{

int dev;

int error;

retry:

if (ida_pre_get(&unnamed_dev_ida, GFP_ATOMIC) == 0)

return -ENOMEM;

spin_lock(&unnamed_dev_lock);

error = ida_get_new_above(&unnamed_dev_ida, unnamed_dev_start, &dev);

if (!error)

unnamed_dev_start = dev + 1;

spin_unlock(&unnamed_dev_lock);

if (error == -EAGAIN)

/* We raced and lost with another CPU. */

goto retry;

else if (error)

return -EAGAIN;

if ((dev & MAX_ID_MASK) == (1 << MINORBITS)) {

spin_lock(&unnamed_dev_lock);

ida_remove(&unnamed_dev_ida, dev);

if (unnamed_dev_start > dev)

unnamed_dev_start = dev;

spin_unlock(&unnamed_dev_lock);

return -EMFILE;

}

s->s_dev = MKDEV(0, dev & MINORMASK);

s->s_bdi = &noop_backing_dev_info;

return 0;

}

EXPORT_SYMBOL(set_anon_super);

void kill_anon_super(struct super_block *sb)

{

int slot = MINOR(sb->s_dev);

generic_shutdown_super(sb);

spin_lock(&unnamed_dev_lock);

ida_remove(&unnamed_dev_ida, slot);

if (slot < unnamed_dev_start)

unnamed_dev_start = slot;

spin_unlock(&unnamed_dev_lock);

}

EXPORT_SYMBOL(kill_anon_super);

void kill_litter_super(struct super_block *sb)

{

if (sb->s_root)

d_genocide(sb->s_root);

kill_anon_super(sb);

}

EXPORT_SYMBOL(kill_litter_super);

static int ns_test_super(struct super_block *sb, void *data)

{

return sb->s_fs_info == data;

}

static int ns_set_super(struct super_block *sb, void *data)

{

sb->s_fs_info = data;

return set_anon_super(sb, NULL);

}

struct dentry *mount_ns(struct file_system_type *fs_type, int flags,

void *data, int (*fill_super)(struct super_block *, void *, int))

{

struct super_block *sb;

sb = sget(fs_type, ns_test_super, ns_set_super, data);

if (IS_ERR(sb))

return ERR_CAST(sb);

if (!sb->s_root) {

int err;

sb->s_flags = flags;

err = fill_super(sb, data, flags & MS_SILENT ? 1 : 0);

if (err) {

deactivate_locked_super(sb);

return ERR_PTR(err);

}

sb->s_flags |= MS_ACTIVE;

}

return dget(sb->s_root);

}

EXPORT_SYMBOL(mount_ns);

#ifdef CONFIG_BLOCK

static int set_bdev_super(struct super_block *s, void *data)

{

s->s_bdev = data;

s->s_dev = s->s_bdev->bd_dev;

/*

* We set the bdi here to the queue backing, file systems can

* overwrite this in ->fill_super()

*/

s->s_bdi = &bdev_get_queue(s->s_bdev)->backing_dev_info;

return 0;

}

static int test_bdev_super(struct super_block *s, void *data)

{

return (void *)s->s_bdev == data;

}

struct dentry *mount_bdev(struct file_system_type *fs_type,

int flags, const char *dev_name, void *data,

int (*fill_super)(struct super_block *, void *, int))

{

struct block_device *bdev;

struct super_block *s;

fmode_t mode = FMODE_READ | FMODE_EXCL;

int error = 0;

if (!(flags & MS_RDONLY))

mode |= FMODE_WRITE;

bdev = blkdev_get_by_path(dev_name, mode, fs_type);

if (IS_ERR(bdev))

return ERR_CAST(bdev);

/*

* once the super is inserted into the list by sget, s_umount

* will protect the lockfs code from trying to start a snapshot

* while we are mounting

*/

mutex_lock(&bdev->bd_fsfreeze_mutex);

if (bdev->bd_fsfreeze_count > 0) {

mutex_unlock(&bdev->bd_fsfreeze_mutex);

error = -EBUSY;

goto error_bdev;

}

s = sget(fs_type, test_bdev_super, set_bdev_super, bdev);

mutex_unlock(&bdev->bd_fsfreeze_mutex);

if (IS_ERR(s))

goto error_s;

if (s->s_root) {

if ((flags ^ s->s_flags) & MS_RDONLY) {

deactivate_locked_super(s);

error = -EBUSY;

goto error_bdev;

}

/*

* s_umount nests inside bd_mutex during

* __invalidate_device(). blkdev_put() acquires

* bd_mutex and can't be called under s_umount. Drop

* s_umount temporarily. This is safe as we're

* holding an active reference.

*/

up_write(&s->s_umount);

blkdev_put(bdev, mode);

down_write(&s->s_umount);

} else {

char b[BDEVNAME_SIZE];

s->s_flags = flags | MS_NOSEC;

s->s_mode = mode;

strlcpy(s->s_id, bdevname(bdev, b), sizeof(s->s_id));

sb_set_blocksize(s, block_size(bdev));

error = fill_super(s, data, flags & MS_SILENT ? 1 : 0);

if (error) {

deactivate_locked_super(s);

goto error;

}

s->s_flags |= MS_ACTIVE;

bdev->bd_super = s;

}

return dget(s->s_root);

error_s:

error = PTR_ERR(s);

error_bdev:

blkdev_put(bdev, mode);

error:

return ERR_PTR(error);

}

EXPORT_SYMBOL(mount_bdev);

void kill_block_super(struct super_block *sb)

{

struct block_device *bdev = sb->s_bdev;

fmode_t mode = sb->s_mode;

bdev->bd_super = NULL;

generic_shutdown_super(sb);

sync_blockdev(bdev);

WARN_ON_ONCE(!(mode & FMODE_EXCL));

blkdev_put(bdev, mode | FMODE_EXCL);

}

EXPORT_SYMBOL(kill_block_super);

#endif

struct dentry *mount_nodev(struct file_system_type *fs_type,

int flags, void *data,

int (*fill_super)(struct super_block *, void *, int))

{

int error;

struct super_block *s = sget(fs_type, NULL, set_anon_super, NULL);

if (IS_ERR(s))

return ERR_CAST(s);

s->s_flags = flags;

error = fill_super(s, data, flags & MS_SILENT ? 1 : 0);

if (error) {

deactivate_locked_super(s);

return ERR_PTR(error);

}

s->s_flags |= MS_ACTIVE;

return dget(s->s_root);

}

EXPORT_SYMBOL(mount_nodev);

static int compare_single(struct super_block *s, void *p)

{

return 1;

}

struct dentry *mount_single(struct file_system_type *fs_type,

int flags, void *data,

int (*fill_super)(struct super_block *, void *, int))

{

struct super_block *s;

int error;

s = sget(fs_type, compare_single, set_anon_super, NULL);

if (IS_ERR(s))

return ERR_CAST(s);

if (!s->s_root) {

s->s_flags = flags;

error = fill_super(s, data, flags & MS_SILENT ? 1 : 0);

if (error) {

deactivate_locked_super(s);

return ERR_PTR(error);

}

s->s_flags |= MS_ACTIVE;

} else {

do_remount_sb(s, flags, data, 0);

}

return dget(s->s_root);

}

EXPORT_SYMBOL(mount_single);

struct dentry *

mount_fs(struct file_system_type *type, int flags, const char *name, void *data)

{

struct dentry *root;

struct super_block *sb;

char *secdata = NULL;

int error = -ENOMEM;

if (data && !(type->fs_flags & FS_BINARY_MOUNTDATA)) {

secdata = alloc_secdata();

if (!secdata)

goto out;

error = security_sb_copy_data(data, secdata);

if (error)

goto out_free_secdata;

}

root = type->mount(type, flags, name, data);

if (IS_ERR(root)) {

error = PTR_ERR(root);

goto out_free_secdata;

}

sb = root->d_sb;

BUG_ON(!sb);

WARN_ON(!sb->s_bdi);

WARN_ON(sb->s_bdi == &default_backing_dev_info);

sb->s_flags |= MS_BORN;

error = security_sb_kern_mount(sb, flags, secdata);

if (error)

goto out_sb;

/*

* filesystems should never set s_maxbytes larger than MAX_LFS_FILESIZE

* but s_maxbytes was an unsigned long long for many releases. Throw

* this warning for a little while to try and catch filesystems that

* violate this rule.

*/

WARN((sb->s_maxbytes < 0), "%s set sb->s_maxbytes to "

"negative value (%lld)\n", type->name, sb->s_maxbytes);

up_write(&sb->s_umount);

free_secdata(secdata);

return root;

out_sb:

dput(root);

deactivate_locked_super(sb);

out_free_secdata:

free_secdata(secdata);

out:

return ERR_PTR(error);

}

/**

* freeze_super - lock the filesystem and force it into a consistent state

* @sb: the super to lock

*

* Syncs the super to make sure the filesystem is consistent and calls the fs's

* freeze_fs. Subsequent calls to this without first thawing the fs will return

* -EBUSY.

*/

int freeze_super(struct super_block *sb)

{

int ret;

atomic_inc(&sb->s_active);

down_write(&sb->s_umount);

if (sb->s_frozen) {

deactivate_locked_super(sb);

return -EBUSY;

}

if (sb->s_flags & MS_RDONLY) {

sb->s_frozen = SB_FREEZE_TRANS;

smp_wmb();

up_write(&sb->s_umount);

return 0;

}

sb->s_frozen = SB_FREEZE_WRITE;

smp_wmb();

sync_filesystem(sb);