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);
s->s_maxbytes = MAX_NON_LFS;
s->s_op = &default_op;
s->s_time_gran = 1000000000;
struct super_block *old;
int err;
- if (!(flags & MS_KERNMOUNT) &&
+ if (!(flags & (MS_KERNMOUNT|MS_SUBMOUNT)) &&
!(type->fs_flags & FS_USERNS_MOUNT) &&
!capable(CAP_SYS_ADMIN))
return ERR_PTR(-EPERM);
}
if (!s) {
spin_unlock(&sb_lock);
- s = alloc_super(type, flags, user_ns);
+ s = alloc_super(type, (flags & ~MS_SUBMOUNT), user_ns);
if (!s)
return ERR_PTR(-ENOMEM);
goto retry;
{
struct user_namespace *user_ns = current_user_ns();
+ /* We don't yet pass the user namespace of the parent
+ * mount through to here so always use &init_user_ns
+ * until that changes.
+ */
+ if (flags & MS_SUBMOUNT)
+ user_ns = &init_user_ns;
+
/* Ensure the requestor has permissions over the target filesystem */
- if (!(flags & MS_KERNMOUNT) && !ns_capable(user_ns, CAP_SYS_ADMIN))
+ if (!(flags & (MS_KERNMOUNT|MS_SUBMOUNT)) && !ns_capable(user_ns, CAP_SYS_ADMIN))
return ERR_PTR(-EPERM);
return sget_userns(type, test, set, flags, user_ns, data);
EXPORT_SYMBOL(drop_super);
+void drop_super_exclusive(struct super_block *sb)
+{
+ up_write(&sb->s_umount);
+ put_super(sb);
+}
+EXPORT_SYMBOL(drop_super_exclusive);
+
/**
* iterate_supers - call function for all active superblocks
* @f: function to call
EXPORT_SYMBOL(iterate_supers_type);
-/**
- * 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)
+static struct super_block *__get_super(struct block_device *bdev, bool excl)
{
struct super_block *sb;
if (sb->s_bdev == bdev) {
sb->s_count++;
spin_unlock(&sb_lock);
- down_read(&sb->s_umount);
+ if (!excl)
+ down_read(&sb->s_umount);
+ else
+ down_write(&sb->s_umount);
/* still alive? */
if (sb->s_root && (sb->s_flags & MS_BORN))
return sb;
- up_read(&sb->s_umount);
+ if (!excl)
+ up_read(&sb->s_umount);
+ else
+ up_write(&sb->s_umount);
/* nope, got unmounted */
spin_lock(&sb_lock);
__put_super(sb);
return NULL;
}
-EXPORT_SYMBOL(get_super);
-
/**
- * get_super_thawed - get thawed superblock of a device
+ * 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. The superblock is returned once it is thawed
- * (or immediately if it was not frozen). %NULL is returned if no match
- * is found.
+ * mounted on the device given. %NULL is returned if no match is found.
*/
-struct super_block *get_super_thawed(struct block_device *bdev)
+struct super_block *get_super(struct block_device *bdev)
+{
+ return __get_super(bdev, false);
+}
+EXPORT_SYMBOL(get_super);
+
+static struct super_block *__get_super_thawed(struct block_device *bdev,
+ bool excl)
{
while (1) {
- struct super_block *s = get_super(bdev);
+ struct super_block *s = __get_super(bdev, excl);
if (!s || s->s_writers.frozen == SB_UNFROZEN)
return s;
- up_read(&s->s_umount);
+ if (!excl)
+ up_read(&s->s_umount);
+ else
+ up_write(&s->s_umount);
wait_event(s->s_writers.wait_unfrozen,
s->s_writers.frozen == SB_UNFROZEN);
put_super(s);
}
}
+
+/**
+ * get_super_thawed - get thawed 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. The superblock is returned once it is thawed
+ * (or immediately if it was not frozen). %NULL is returned if no match
+ * is found.
+ */
+struct super_block *get_super_thawed(struct block_device *bdev)
+{
+ return __get_super_thawed(bdev, false);
+}
EXPORT_SYMBOL(get_super_thawed);
+/**
+ * get_super_exclusive_thawed - get thawed 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. The superblock is returned once it is thawed
+ * (or immediately if it was not frozen) and s_umount semaphore is held
+ * in exclusive mode. %NULL is returned if no match is found.
+ */
+struct super_block *get_super_exclusive_thawed(struct block_device *bdev)
+{
+ return __get_super_thawed(bdev, true);
+}
+EXPORT_SYMBOL(get_super_exclusive_thawed);
+
/**
* get_active_super - get an active reference to the superblock of a device
* @bdev: device to get the superblock for
if (IS_ERR(bdev))
return ERR_CAST(bdev);
+ if (current_user_ns() != &init_user_ns) {
+ /*
+ * For userns mounts, disallow mounting if bdev is open for
+ * writing
+ */
+ if (!atomic_dec_unless_positive(&bdev->bd_inode->i_writecount)) {
+ error = -EBUSY;
+ goto error_bdev;
+ }
+ if (bdev->bd_contains != bdev &&
+ !atomic_dec_unless_positive(&bdev->bd_contains->bd_inode->i_writecount)) {
+ atomic_inc(&bdev->bd_inode->i_writecount);
+ error = -EBUSY;
+ goto error_bdev;
+ }
+ }
+
/*
* once the super is inserted into the list by sget, s_umount
* will protect the lockfs code from trying to start a snapshot
if (bdev->bd_fsfreeze_count > 0) {
mutex_unlock(&bdev->bd_fsfreeze_mutex);
error = -EBUSY;
- goto error_bdev;
+ goto error_inc;
}
s = sget(fs_type, test_bdev_super, set_bdev_super, flags | MS_NOSEC,
bdev);
if ((flags ^ s->s_flags) & MS_RDONLY) {
deactivate_locked_super(s);
error = -EBUSY;
- goto error_bdev;
+ goto error_inc;
}
/*
error_s:
error = PTR_ERR(s);
+error_inc:
+ if (current_user_ns() != &init_user_ns) {
+ atomic_inc(&bdev->bd_inode->i_writecount);
+ if (bdev->bd_contains != bdev)
+ atomic_inc(&bdev->bd_contains->bd_inode->i_writecount);
+ }
error_bdev:
blkdev_put(bdev, mode);
error:
generic_shutdown_super(sb);
sync_blockdev(bdev);
WARN_ON_ONCE(!(mode & FMODE_EXCL));
+ if (sb->s_user_ns != &init_user_ns) {
+ atomic_inc(&bdev->bd_inode->i_writecount);
+ if (bdev->bd_contains != bdev)
+ atomic_inc(&bdev->bd_contains->bd_inode->i_writecount);
+ }
blkdev_put(bdev, mode | FMODE_EXCL);
}
projects / mirror_ubuntu-zesty-kernel.git / blobdiff