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 | 94 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
fs/btrfs/sysfs.h | 37 +++++++++++++++++++++
2 files changed, 131 insertions(+)
--- a/fs/btrfs/sysfs.c 2013-09-10 00:07:58.567116997 -0400
+++ b/fs/btrfs/sysfs.c 2013-09-10 00:08:31.714646494 -0400
@@ -26,20 +26,114 @@
#include "ctree.h"
#include "disk-io.h"
#include "transaction.h"
+#include "sysfs.h"
/* /sys/fs/btrfs/ entry */
static struct kset *btrfs_kset;
+struct btrfs_features {
+ struct kobject f_kobj;
+ struct completion f_kobj_unregister;
+};
+
+struct btrfs_features *btrfs_feat;
+
+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_supp_feature_attrs[] = {
+ BTRFS_SUPP_FEAT_LIST(mixed_backref)
+ BTRFS_SUPP_FEAT_LIST(default_subvol)
+ BTRFS_SUPP_FEAT_LIST(mixed_groups)
+ BTRFS_SUPP_FEAT_LIST(compress_lzo)
+ BTRFS_SUPP_FEAT_LIST(compress_lzov2)
+ BTRFS_SUPP_FEAT_LIST(big_metadata)
+ BTRFS_SUPP_FEAT_LIST(extended_iref)
+ BTRFS_SUPP_FEAT_LIST(raid56)
+ BTRFS_SUPP_FEAT_LIST(skinny_metadata)
+ NULL
+};
+
+static void btrfs_supp_feat_release(struct kobject *kobj)
+{
+ complete(&btrfs_feat->f_kobj_unregister);
+}
+
+static ssize_t btrfs_supp_attr_show(struct kobject *kobj, struct attribute *a,
+ char *buf)
+{
+ return snprintf(buf, PAGE_SIZE, "0\n");
+}
+
+static const struct sysfs_ops btrfs_supp_attr_ops = {
+ .show = btrfs_supp_attr_show,
+};
+
+static struct kobj_type btrfs_supp_feat_ktype = {
+ .default_attrs = btrfs_supp_feature_attrs,
+ .sysfs_ops = &btrfs_supp_attr_ops,
+ .release = btrfs_supp_feat_release,
+};
+
+static int __init btrfs_init_feat_adverts(void)
+{
+ struct btrfs_features *bf;
+ int ret = -ENOMEM;
+
+ bf = kzalloc(sizeof(struct btrfs_features), GFP_KERNEL);
+ if (!bf)
+ goto out;
+
+ bf->f_kobj.kset = btrfs_kset;
+ init_completion(&bf->f_kobj_unregister);
+
+ ret = kobject_init_and_add(&bf->f_kobj, &btrfs_supp_feat_ktype, NULL,
+ "features");
+ if (ret) {
+ kfree(bf);
+ goto out;
+ }
+
+ btrfs_feat = bf;
+ ret = 0;
+out:
+ return ret;
+}
+
+static void btrfs_exit_feat_adverts(void)
+{
+ kobject_del(&btrfs_feat->f_kobj);
+ kobject_put(&btrfs_feat->f_kobj);
+ wait_for_completion(&btrfs_feat->f_kobj_unregister);
+ kfree(btrfs_feat);
+}
+
int btrfs_init_sysfs(void)
{
+ int ret;
btrfs_kset = kset_create_and_add("btrfs", NULL, fs_kobj);
if (!btrfs_kset)
return -ENOMEM;
+
+ ret = btrfs_init_feat_adverts();
+ if (ret) {
+ kset_unregister(btrfs_kset);
+ return ret;
+ }
+
return 0;
}
void btrfs_exit_sysfs(void)
{
+ btrfs_exit_feat_adverts();
kset_unregister(btrfs_kset);
}
--- /dev/null 1970-01-01 00:00:00.000000000 +0000
+++ b/fs/btrfs/sysfs.h 2013-09-10 00:09:00.778250180 -0400
@@ -0,0 +1,37 @@
+#ifndef _BTRFS_SYSFS_H_
+#define _BTRFS_SYSFS_H_
+
+enum btrfs_feature_set {
+ FEAT_COMPAT,
+ FEAT_COMPAT_RO,
+ FEAT_INCOMPAT,
+ FEAT_MAX
+};
+
+struct btrfs_feature_attr {
+ struct attribute attr; /* global show, no store */
+ 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 = {
\
+ .attr = { .name = __stringify(_name), .mode = S_IRUGO, }, \
+ .feature_set = _feature_set, \
+ .feature_bit = _prefix ##_## _feature_bit, \
+}
+
+#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)
+
+#define BTRFS_SUPP_FEAT_LIST(_name) (&btrfs_attr_##_name.attr),
+
+/* convert from attribute */
+#define to_btrfs_feature_attr(a) \
+ container_of(a, struct btrfs_feature_attr, attr)
+
+#endif /* _BTRFS_SYSFS_H_ */
--
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