Commit 22c55e3b authored by Stefan Roesch's avatar Stefan Roesch Committed by David Sterba
Browse files

btrfs: sysfs: add force_chunk_alloc trigger to force allocation 



Adds write-only trigger to force new chunk allocation for a given block
group type. It is at

  /sys/fs/btrfs/<uuid>/allocation/<type>/force_chunk_alloc

Note: this is now only for debugging and testing and is enabled with the
      CONFIG_BTRFS_DEBUG configuration option. The transaction is
      started from sysfs context and can be problematic in some cases.

Signed-off-by: default avatarStefan Roesch <shr@fb.com>
Reviewed-by: default avatarDavid Sterba <dsterba@suse.com>
[ Changes from the original submission:
  - update changelog
  - drop unnecessary error messages
  - switch value to bool and use kstrtobool
  - move BTRFS_ATTR_W definition
  - add comment for using transaction
]
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent 19fc516a

fs/btrfs/sysfs.c

+53 −0
Original line number Diff line number Diff line
@@ -62,6 +62,10 @@ struct raid_kobject { 
	.store	= _store,						\

}



#define BTRFS_ATTR_W(_prefix, _name, _store)			        \

	static struct kobj_attribute btrfs_attr_##_prefix##_##_name =	\

			__INIT_KOBJ_ATTR(_name, 0200, NULL, _store)



#define BTRFS_ATTR_RW(_prefix, _name, _show, _store)			\

	static struct kobj_attribute btrfs_attr_##_prefix##_##_name =	\

			__INIT_KOBJ_ATTR(_name, 0644, _show, _store)
@@ -771,6 +775,52 @@ static ssize_t btrfs_chunk_size_store(struct kobject *kobj, 
	return len;

}



#ifdef CONFIG_BTRFS_DEBUG

/*

 * Request chunk allocation with current chunk size.

 */

static ssize_t btrfs_force_chunk_alloc_store(struct kobject *kobj,

					     struct kobj_attribute *a,

					     const char *buf, size_t len)

{

	struct btrfs_space_info *space_info = to_space_info(kobj);

	struct btrfs_fs_info *fs_info = to_fs_info(get_btrfs_kobj(kobj));

	struct btrfs_trans_handle *trans;

	bool val;

	int ret;



	if (!capable(CAP_SYS_ADMIN))

		return -EPERM;



	if (sb_rdonly(fs_info->sb))

		return -EROFS;



	ret = kstrtobool(buf, &val);

	if (ret)

		return ret;



	if (!val)

		return -EINVAL;



	/*

	 * This is unsafe to be called from sysfs context and may cause

	 * unexpected problems.

	 */

	trans = btrfs_start_transaction(fs_info->tree_root, 0);

	if (IS_ERR(trans))

		return PTR_ERR(trans);

	ret = btrfs_force_chunk_alloc(trans, space_info->flags);

	btrfs_end_transaction(trans);



	if (ret == 1)

		return len;



	return -ENOSPC;

}

BTRFS_ATTR_W(space_info, force_chunk_alloc, btrfs_force_chunk_alloc_store);



#endif



SPACE_INFO_ATTR(flags);

SPACE_INFO_ATTR(total_bytes);

SPACE_INFO_ATTR(bytes_used);
@@ -837,6 +887,9 @@ static struct attribute *space_info_attrs[] = { 
	BTRFS_ATTR_PTR(space_info, disk_total),

	BTRFS_ATTR_PTR(space_info, bg_reclaim_threshold),

	BTRFS_ATTR_PTR(space_info, chunk_size),

#ifdef CONFIG_BTRFS_DEBUG

	BTRFS_ATTR_PTR(space_info, force_chunk_alloc),

#endif

	NULL,

};

ATTRIBUTE_GROUPS(space_info);