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Commit 079b72bc authored by Jeff Mahoney's avatar Jeff Mahoney Committed by Chris Mason
Browse files

btrfs: publish supported featured in sysfs 



This patch adds the ability to publish supported features to sysfs under
/sys/fs/btrfs/features.

The files are module-wide and export which features the kernel supports.

The content, for now, is just "0\n".

Signed-off-by: default avatarJeff Mahoney <jeffm@suse.com>
Signed-off-by: default avatarJosef Bacik <jbacik@fusionio.com>
Signed-off-by: default avatarChris Mason <clm@fb.com>
parent 29dfe2dc

fs/btrfs/sysfs.c

+44 −0
Original line number Diff line number Diff line
@@ -26,20 +26,64 @@ 
#include "ctree.h"

#include "disk-io.h"

#include "transaction.h"

#include "sysfs.h"



static ssize_t btrfs_feature_attr_show(struct kobject *kobj,

				       struct kobj_attribute *a, char *buf)

{

	return snprintf(buf, PAGE_SIZE, "0\n");

}



BTRFS_FEAT_ATTR_INCOMPAT(mixed_backref, MIXED_BACKREF);

BTRFS_FEAT_ATTR_INCOMPAT(default_subvol, DEFAULT_SUBVOL);

BTRFS_FEAT_ATTR_INCOMPAT(mixed_groups, MIXED_GROUPS);

BTRFS_FEAT_ATTR_INCOMPAT(compress_lzo, COMPRESS_LZO);

BTRFS_FEAT_ATTR_INCOMPAT(compress_lzov2, COMPRESS_LZOv2);

BTRFS_FEAT_ATTR_INCOMPAT(big_metadata, BIG_METADATA);

BTRFS_FEAT_ATTR_INCOMPAT(extended_iref, EXTENDED_IREF);

BTRFS_FEAT_ATTR_INCOMPAT(raid56, RAID56);

BTRFS_FEAT_ATTR_INCOMPAT(skinny_metadata, SKINNY_METADATA);



static struct attribute *btrfs_supported_feature_attrs[] = {

	BTRFS_FEAT_ATTR_PTR(mixed_backref),

	BTRFS_FEAT_ATTR_PTR(default_subvol),

	BTRFS_FEAT_ATTR_PTR(mixed_groups),

	BTRFS_FEAT_ATTR_PTR(compress_lzo),

	BTRFS_FEAT_ATTR_PTR(compress_lzov2),

	BTRFS_FEAT_ATTR_PTR(big_metadata),

	BTRFS_FEAT_ATTR_PTR(extended_iref),

	BTRFS_FEAT_ATTR_PTR(raid56),

	BTRFS_FEAT_ATTR_PTR(skinny_metadata),

	NULL

};



static const struct attribute_group btrfs_feature_attr_group = {

	.name = "features",

	.attrs = btrfs_supported_feature_attrs,

};



/* /sys/fs/btrfs/ entry */

static struct kset *btrfs_kset;



int btrfs_init_sysfs(void)

{

	int ret;

	btrfs_kset = kset_create_and_add("btrfs", NULL, fs_kobj);

	if (!btrfs_kset)

		return -ENOMEM;



	ret = sysfs_create_group(&btrfs_kset->kobj, &btrfs_feature_attr_group);

	if (ret) {

		kset_unregister(btrfs_kset);

		return ret;

	}



	return 0;

}



void btrfs_exit_sysfs(void)

{

	sysfs_remove_group(&btrfs_kset->kobj, &btrfs_feature_attr_group);

	kset_unregister(btrfs_kset);

}

fs/btrfs/sysfs.h

0 → 100644
+43 −0
Original line number Diff line number Diff line 
#ifndef _BTRFS_SYSFS_H_

#define _BTRFS_SYSFS_H_



enum btrfs_feature_set {

	FEAT_COMPAT,

	FEAT_COMPAT_RO,

	FEAT_INCOMPAT,

	FEAT_MAX

};



#define __INIT_KOBJ_ATTR(_name, _mode, _show, _store)			\

{									\

	.attr	= { .name = __stringify(_name), .mode = _mode },	\

	.show	= _show,						\

	.store	= _store,						\

}



struct btrfs_feature_attr {

	struct kobj_attribute kobj_attr;

	enum btrfs_feature_set feature_set;

	u64 feature_bit;

};



#define BTRFS_FEAT_ATTR(_name, _feature_set, _prefix, _feature_bit)	     \

static struct btrfs_feature_attr btrfs_attr_##_name = {			     \

	.kobj_attr = __INIT_KOBJ_ATTR(_name, S_IRUGO,			     \

				      btrfs_feature_attr_show, NULL),	     \

	.feature_set	= _feature_set,					     \

	.feature_bit	= _prefix ##_## _feature_bit,			     \

}

#define BTRFS_FEAT_ATTR_PTR(_name)    (&btrfs_attr_##_name.kobj_attr.attr)



#define BTRFS_FEAT_ATTR_COMPAT(name, feature) \

	BTRFS_FEAT_ATTR(name, FEAT_COMPAT, BTRFS_FEATURE_COMPAT, feature)

#define BTRFS_FEAT_ATTR_COMPAT_RO(name, feature) \

	BTRFS_FEAT_ATTR(name, FEAT_COMPAT_RO, BTRFS_FEATURE_COMPAT, feature)

#define BTRFS_FEAT_ATTR_INCOMPAT(name, feature) \

	BTRFS_FEAT_ATTR(name, FEAT_INCOMPAT, BTRFS_FEATURE_INCOMPAT, feature)



/* convert from attribute */

#define to_btrfs_feature_attr(a) \

			container_of(a, struct btrfs_feature_attr, kobj_attr)

#endif /* _BTRFS_SYSFS_H_ */