[PATCH v2 8/9] nilfs2: add /sys/fs/nilfs/<device>/mounted_snapshots/<snapshot> group

[Vyacheslav Dubeyko]

From: Vyacheslav Dubeyko <Vyacheslav.Dubeyko-***@public.gmane.org>
Subject: [PATCH v2 8/9] nilfs2: add /sys/fs/nilfs/<device>/mounted_snapshots/<snapshot> group

This patch adds creation of <snapshot> group for every mounted
snapshot in /sys/fs/nilfs/<device>/mounted_snapshots group.

The group contains details about mounted snapshot:
(1) inodes_count - show number of inodes for snapshot.
(2) blocks_count - show number of blocks for snapshot.

Signed-off-by: Vyacheslav Dubeyko <Vyacheslav.Dubeyko-***@public.gmane.org>
CC: Vyacheslav Dubeyko <slava-***@public.gmane.org>
CC: Ryusuke Konishi <konishi.ryusuke-***@public.gmane.org>
CC: Michael L. Semon <mlsemon35-***@public.gmane.org>
---
fs/nilfs2/sysfs.c | 118 +++++++++++++++++++++++++++++++++++++++++++++++++
fs/nilfs2/sysfs.h | 20 +++++++++
fs/nilfs2/the_nilfs.h | 6 +++
3 files changed, 144 insertions(+)

diff --git a/fs/nilfs2/sysfs.c b/fs/nilfs2/sysfs.c
index c899818..622ddcf 100644
--- a/fs/nilfs2/sysfs.c
+++ b/fs/nilfs2/sysfs.c
@@ -122,6 +122,124 @@ void nilfs_sysfs_delete_##name##_group(struct the_nilfs *nilfs) \
}

/************************************************************************
+ * NILFS snapshot attrs *
+ ************************************************************************/
+
+static ssize_t
+nilfs_snapshot_inodes_count_show(struct nilfs_snapshot_attr *attr,
+ struct nilfs_root *root, char *buf)
+{
+ return snprintf(buf, PAGE_SIZE, "%llu\n",
+ (unsigned long long)atomic64_read(&root->inodes_count));
+}
+
+static ssize_t
+nilfs_snapshot_blocks_count_show(struct nilfs_snapshot_attr *attr,
+ struct nilfs_root *root, char *buf)
+{
+ return snprintf(buf, PAGE_SIZE, "%llu\n",
+ (unsigned long long)atomic64_read(&root->blocks_count));
+}
+
+static const char snapshot_readme_str[] =
+ "The group contains details about mounted snapshot.\n\n"
+ "(1) inodes_count\n\tshow number of inodes for snapshot.\n\n"
+ "(2) blocks_count\n\tshow number of blocks for snapshot.\n\n";
+
+static ssize_t
+nilfs_snapshot_README_show(struct nilfs_snapshot_attr *attr,
+ struct nilfs_root *root, char *buf)
+{
+ return snprintf(buf, PAGE_SIZE, snapshot_readme_str);
+}
+
+NILFS_SNAPSHOT_RO_ATTR(inodes_count);
+NILFS_SNAPSHOT_RO_ATTR(blocks_count);
+NILFS_SNAPSHOT_RO_ATTR(README);
+
+static struct attribute *nilfs_snapshot_attrs[] = {
+ NILFS_SNAPSHOT_ATTR_LIST(inodes_count),
+ NILFS_SNAPSHOT_ATTR_LIST(blocks_count),
+ NILFS_SNAPSHOT_ATTR_LIST(README),
+ NULL,
+};
+
+static ssize_t nilfs_snapshot_attr_show(struct kobject *kobj,
+ struct attribute *attr, char *buf)
+{
+ struct nilfs_root *root =
+ container_of(kobj, struct nilfs_root, snapshot_kobj);
+ struct nilfs_snapshot_attr *a =
+ container_of(attr, struct nilfs_snapshot_attr, attr);
+
+ return a->show ? a->show(a, root, buf) : 0;
+}
+
+static ssize_t nilfs_snapshot_attr_store(struct kobject *kobj,
+ struct attribute *attr,
+ const char *buf, size_t len)
+{
+ struct nilfs_root *root =
+ container_of(kobj, struct nilfs_root, snapshot_kobj);
+ struct nilfs_snapshot_attr *a =
+ container_of(attr, struct nilfs_snapshot_attr, attr);
+
+ return a->store ? a->store(a, root, buf, len) : 0;
+}
+
+static void nilfs_snapshot_attr_release(struct kobject *kobj)
+{
+ struct nilfs_root *root = container_of(kobj, struct nilfs_root,
+ snapshot_kobj);
+ complete(&root->snapshot_kobj_unregister);
+}
+
+static const struct sysfs_ops nilfs_snapshot_attr_ops = {
+ .show = nilfs_snapshot_attr_show,
+ .store = nilfs_snapshot_attr_store,
+};
+
+static struct kobj_type nilfs_snapshot_ktype = {
+ .default_attrs = nilfs_snapshot_attrs,
+ .sysfs_ops = &nilfs_snapshot_attr_ops,
+ .release = nilfs_snapshot_attr_release,
+};
+
+int nilfs_sysfs_create_snapshot_group(struct nilfs_root *root)
+{
+ struct the_nilfs *nilfs;
+ struct kobject *parent;
+ int err;
+
+ nilfs = root->nilfs;
+ parent = &nilfs->ns_dev_subgroups->sg_mounted_snapshots_kobj;
+ root->snapshot_kobj.kset = nilfs_kset;
+ init_completion(&root->snapshot_kobj_unregister);
+
+ if (root->cno == NILFS_CPTREE_CURRENT_CNO) {
+ err = kobject_init_and_add(&root->snapshot_kobj,
+ &nilfs_snapshot_ktype,
+ &nilfs->ns_dev_kobj,
+ "current_checkpoint");
+ } else {
+ err = kobject_init_and_add(&root->snapshot_kobj,
+ &nilfs_snapshot_ktype,
+ parent,
+ "%llu", root->cno);
+ }
+
+ if (err)
+ return err;
+
+ return 0;
+}
+
+void nilfs_sysfs_delete_snapshot_group(struct nilfs_root *root)
+{
+ kobject_del(&root->snapshot_kobj);
+}
+
+/************************************************************************
* NILFS mounted snapshots attrs *
************************************************************************/

diff --git a/fs/nilfs2/sysfs.h b/fs/nilfs2/sysfs.h
index f8ba9b6..d2a92f1 100644
--- a/fs/nilfs2/sysfs.h
+++ b/fs/nilfs2/sysfs.h
@@ -84,6 +84,17 @@ NILFS_DEV_ATTR_STRUCT(checkpoints);
NILFS_DEV_ATTR_STRUCT(superblock);
NILFS_DEV_ATTR_STRUCT(segctor);

+#define NILFS_CP_ATTR_STRUCT(name) \
+struct nilfs_##name##_attr { \
+ struct attribute attr; \
+ ssize_t (*show)(struct nilfs_##name##_attr *, struct nilfs_root *, \
+ char *); \
+ ssize_t (*store)(struct nilfs_##name##_attr *, struct nilfs_root *, \
+ const char *, size_t); \
+};
+
+NILFS_CP_ATTR_STRUCT(snapshot);
+
#define NILFS_ATTR(type, name, mode, show, store) \
static struct nilfs_##type##_attr nilfs_##type##_attr_##name = \
__ATTR(name, mode, show, store)
@@ -124,6 +135,13 @@ NILFS_DEV_ATTR_STRUCT(segctor);
#define NILFS_CHECKPOINTS_RW_ATTR(name) \
NILFS_RW_ATTR(checkpoints, name)

+#define NILFS_SNAPSHOT_INFO_ATTR(name) \
+ NILFS_INFO_ATTR(snapshot, name)
+#define NILFS_SNAPSHOT_RO_ATTR(name) \
+ NILFS_RO_ATTR(snapshot, name)
+#define NILFS_SNAPSHOT_RW_ATTR(name) \
+ NILFS_RW_ATTR(snapshot, name)
+
#define NILFS_SUPERBLOCK_RO_ATTR(name) \
NILFS_RO_ATTR(superblock, name)
#define NILFS_SUPERBLOCK_RW_ATTR(name) \
@@ -146,6 +164,8 @@ NILFS_DEV_ATTR_STRUCT(segctor);
(&nilfs_mounted_snapshots_attr_##name.attr)
#define NILFS_CHECKPOINTS_ATTR_LIST(name) \
(&nilfs_checkpoints_attr_##name.attr)
+#define NILFS_SNAPSHOT_ATTR_LIST(name) \
+ (&nilfs_snapshot_attr_##name.attr)
#define NILFS_SUPERBLOCK_ATTR_LIST(name) \
(&nilfs_superblock_attr_##name.attr)
#define NILFS_SEGCTOR_ATTR_LIST(name) \
diff --git a/fs/nilfs2/the_nilfs.h b/fs/nilfs2/the_nilfs.h
index 315634a..456e308 100644
--- a/fs/nilfs2/the_nilfs.h
+++ b/fs/nilfs2/the_nilfs.h
@@ -243,6 +243,8 @@ THE_NILFS_FNS(SB_DIRTY, sb_dirty)
* @ifile: inode file
* @inodes_count: number of inodes
* @blocks_count: number of blocks
+ * @snapshot_kobj: /sys/fs/nilfs/<device>/mounted_snapshots/<snapshot>
+ * @snapshot_kobj_unregister: completion state for kernel object
*/
struct nilfs_root {
__u64 cno;
@@ -254,6 +256,10 @@ struct nilfs_root {

atomic64_t inodes_count;
atomic64_t blocks_count;
+
+ /* /sys/fs/nilfs/<device>/mounted_snapshots/<snapshot> */
+ struct kobject snapshot_kobj;
+ struct completion snapshot_kobj_unregister;
};

/* Special checkpoint number */