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 <je...@suse.com>
---
fs/btrfs/sysfs.c | 44 ++++++++++++++++++++++++++++++++++++++++++++
fs/btrfs/sysfs.h | 43 +++++++++++++++++++++++++++++++++++++++++++
2 files changed, 87 insertions(+)
--- a/fs/btrfs/sysfs.c 2013-10-21 16:09:52.760201346 -0400
+++ b/fs/btrfs/sysfs.c 2013-10-21 16:09:59.816046422 -0400
@@ -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);
}
--- /dev/null 1970-01-01 00:00:00.000000000 +0000
+++ b/fs/btrfs/sysfs.h 2013-10-21 16:09:59.816046422 -0400
@@ -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_ */
--
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