EXPORT_SYMBOL(deactivate_super);
+/**
+ * deactivate_locked_super - drop an active reference to superblock
+ * @s: superblock to deactivate
+ *
+ * Equivalent of up_write(&s->s_umount); deactivate_super(s);, except that
+ * it does not unlock it until it's all over. As the result, it's safe to
+ * use to dispose of new superblock on ->get_sb() failure exits - nobody
+ * will see the sucker until it's all over. Equivalent using up_write +
+ * deactivate_super is safe for that purpose only if superblock is either
+ * safe to use or has NULL ->s_root when we unlock.
+ */
+void deactivate_locked_super(struct super_block *s)
+{
+ struct file_system_type *fs = s->s_type;
+ if (atomic_dec_and_lock(&s->s_active, &sb_lock)) {
+ s->s_count -= S_BIAS-1;
+ spin_unlock(&sb_lock);
+ vfs_dq_off(s, 0);
+ fs->kill_sb(s);
+ put_filesystem(fs);
+ put_super(s);
+ } else {
+ up_write(&s->s_umount);
+ }
+}
+
+EXPORT_SYMBOL(deactivate_locked_super);
+
/**
* grab_super - acquire an active reference
* @s: reference we are trying to make active
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);
+}
+
+int get_sb_ns(struct file_system_type *fs_type, int flags, void *data,
+ int (*fill_super)(struct super_block *, void *, int),
+ struct vfsmount *mnt)
+{
+ struct super_block *sb;
+
+ sb = sget(fs_type, ns_test_super, ns_set_super, data);
+ if (IS_ERR(sb))
+ return PTR_ERR(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;
+ }
+
+ sb->s_flags |= MS_ACTIVE;
+ }
+
+ simple_set_mnt(mnt, sb);
+ return 0;
+}
+
+EXPORT_SYMBOL(get_sb_ns);
+
#ifdef CONFIG_BLOCK
static int set_bdev_super(struct super_block *s, void *data)
{
if (s->s_root) {
if ((flags ^ s->s_flags) & MS_RDONLY) {
- up_write(&s->s_umount);
- deactivate_super(s);
+ deactivate_locked_super(s);
error = -EBUSY;
goto error_bdev;
}
sb_set_blocksize(s, block_size(bdev));
error = fill_super(s, data, flags & MS_SILENT ? 1 : 0);
if (error) {
- up_write(&s->s_umount);
- deactivate_super(s);
+ deactivate_locked_super(s);
goto error;
}
struct block_device *bdev = sb->s_bdev;
fmode_t mode = sb->s_mode;
- bdev->bd_super = 0;
+ bdev->bd_super = NULL;
generic_shutdown_super(sb);
sync_blockdev(bdev);
close_bdev_exclusive(bdev, mode);
error = fill_super(s, data, flags & MS_SILENT ? 1 : 0);
if (error) {
- up_write(&s->s_umount);
- deactivate_super(s);
+ deactivate_locked_super(s);
return error;
}
s->s_flags |= MS_ACTIVE;
s->s_flags = flags;
error = fill_super(s, data, flags & MS_SILENT ? 1 : 0);
if (error) {
- up_write(&s->s_umount);
- deactivate_super(s);
+ deactivate_locked_super(s);
return error;
}
s->s_flags |= MS_ACTIVE;
return mnt;
out_sb:
dput(mnt->mnt_root);
- up_write(&mnt->mnt_sb->s_umount);
- deactivate_super(mnt->mnt_sb);
+ deactivate_locked_super(mnt->mnt_sb);
out_free_secdata:
free_secdata(secdata);
out_mnt: