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btrfs: publish supported featured in sysfs

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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: Jeff Mahoney <jeffm@suse.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <clm@fb.com>
This commit is contained in:
Jeff Mahoney 2013-11-01 13:06:57 -04:00 committed by Chris Mason
parent 29dfe2dc0e
commit 079b72bca3
2 changed files with 87 additions and 0 deletions
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44
fs/btrfs/sysfs.c
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@ -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);
}

43
fs/btrfs/sysfs.h Normal file
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@ -0,0 +1,43 @@
#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_ */