[PATCH V4 05/12] kernfs: introduce kernfs_node_id

Shaohua Li
2017-06-28T16:32:42Z

From: Shaohua Li <shli@fb.com>

inode number and generation can identify a kernfs node. We are going to
export the identification by exportfs operations, so put ino and
generation into a separate structure. It's convenient when later patches
use the identification.

Signed-off-by: Shaohua Li <shli@fb.com>
---
fs/kernfs/dir.c | 10 +++++-----
fs/kernfs/file.c | 4 ++--
fs/kernfs/inode.c | 4 ++--
include/linux/cgroup.h | 2 +-
include/linux/kernfs.h | 12 ++++++++++--
include/trace/events/writeback.h | 2 +-
6 files changed, 21 insertions(+), 13 deletions(-)

diff --git a/fs/kernfs/dir.c b/fs/kernfs/dir.c
index b61a7ef..89d1dc1 100644
--- a/fs/kernfs/dir.c
+++ b/fs/kernfs/dir.c
@@ -539,7 +539,7 @@ void kernfs_put(struct kernfs_node *kn)
}
kfree(kn->iattr);
spin_lock(&kernfs_idr_lock);
- idr_remove(&root->ino_idr, kn->ino);
+ idr_remove(&root->ino_idr, kn->id.ino);
spin_unlock(&kernfs_idr_lock);
kmem_cache_free(kernfs_node_cache, kn);

@@ -645,8 +645,8 @@ static struct kernfs_node *__kernfs_new_node(struct kernfs_root *root,
idr_preload_end();
if (ret < 0)
goto err_out2;
- kn->ino = ret;
- kn->generation = gen;
+ kn->id.ino = ret;
+ kn->id.generation = gen;

/*
* set ino first. This barrier is paired with atomic_inc_not_zero in
@@ -721,7 +721,7 @@ struct kernfs_node *kernfs_find_and_get_node_by_ino(struct kernfs_root *root,
* before 'count'. So if 'count' is uptodate, 'ino' should be uptodate,
* hence we can use 'ino' to filter stale node.
*/
- if (kn->ino != ino)
+ if (kn->id.ino != ino)
goto out;
rcu_read_unlock();

@@ -1654,7 +1654,7 @@ static int kernfs_fop_readdir(struct file *file, struct dir_context *ctx)
const char *name = pos->name;
unsigned int type = dt_type(pos);
int len = strlen(name);
- ino_t ino = pos->ino;
+ ino_t ino = pos->id.ino;

ctx->pos = pos->hash;
file->private_data = pos;
diff --git a/fs/kernfs/file.c b/fs/kernfs/file.c
index 7f90d4d..7441925 100644
--- a/fs/kernfs/file.c
+++ b/fs/kernfs/file.c
@@ -895,7 +895,7 @@ static void kernfs_notify_workfn(struct work_struct *work)
* have the matching @file available. Look up the inodes
* and generate the events manually.
*/
- inode = ilookup(info->sb, kn->ino);
+ inode = ilookup(info->sb, kn->id.ino);
if (!inode)
continue;

@@ -903,7 +903,7 @@ static void kernfs_notify_workfn(struct work_struct *work)
if (parent) {
struct inode *p_inode;

- p_inode = ilookup(info->sb, parent->ino);
+ p_inode = ilookup(info->sb, parent->id.ino);
if (p_inode) {
fsnotify(p_inode, FS_MODIFY | FS_EVENT_ON_CHILD,
inode, FSNOTIFY_EVENT_INODE, kn->name, 0);
diff --git a/fs/kernfs/inode.c b/fs/kernfs/inode.c
index 4c8b510..a343039 100644
--- a/fs/kernfs/inode.c
+++ b/fs/kernfs/inode.c
@@ -220,7 +220,7 @@ static void kernfs_init_inode(struct kernfs_node *kn, struct inode *inode)
inode->i_private = kn;
inode->i_mapping->a_ops = &kernfs_aops;
inode->i_op = &kernfs_iops;
- inode->i_generation = kn->generation;
+ inode->i_generation = kn->id.generation;

set_default_inode_attr(inode, kn->mode);
kernfs_refresh_inode(kn, inode);
@@ -266,7 +266,7 @@ struct inode *kernfs_get_inode(struct super_block *sb, struct kernfs_node *kn)
{
struct inode *inode;

- inode = iget_locked(sb, kn->ino);
+ inode = iget_locked(sb, kn->id.ino);
if (inode && (inode->i_state & I_NEW))
kernfs_init_inode(kn, inode);

diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
index 710a005..30c6877 100644
--- a/include/linux/cgroup.h
+++ b/include/linux/cgroup.h
@@ -543,7 +543,7 @@ static inline bool cgroup_is_populated(struct cgroup *cgrp)
/* returns ino associated with a cgroup */
static inline ino_t cgroup_ino(struct cgroup *cgrp)
{
- return cgrp->kn->ino;
+ return cgrp->kn->id.ino;
}

/* cft/css accessors for cftype->write() operation */
diff --git a/include/linux/kernfs.h b/include/linux/kernfs.h
index 8c00d28..06a0c59 100644
--- a/include/linux/kernfs.h
+++ b/include/linux/kernfs.h
@@ -95,6 +95,15 @@ struct kernfs_elem_attr {
struct kernfs_node *notify_next; /* for kernfs_notify() */
};

+/* represent a kernfs node */
+union kernfs_node_id {
+ struct {
+ u32 ino;
+ u32 generation;
+ };
+ u64 id;
+};
+
/*
* kernfs_node - the building block of kernfs hierarchy. Each and every
* kernfs node is represented by single kernfs_node. Most fields are
@@ -131,11 +140,10 @@ struct kernfs_node {

void *priv;

+ union kernfs_node_id id;
unsigned short flags;
umode_t mode;
- unsigned int ino;
struct kernfs_iattrs *iattr;
- u32 generation;
};

/*
diff --git a/include/trace/events/writeback.h b/include/trace/events/writeback.h
index 7bd8783..9b57f01 100644
--- a/include/trace/events/writeback.h
+++ b/include/trace/events/writeback.h
@@ -136,7 +136,7 @@ DEFINE_EVENT(writeback_dirty_inode_template, writeback_dirty_inode,

static inline unsigned int __trace_wb_assign_cgroup(struct bdi_writeback *wb)
{
- return wb->memcg_css->cgroup->kn->ino;
+ return wb->memcg_css->cgroup->kn->id.ino;
}

static inline unsigned int __trace_wbc_assign_cgroup(struct writeback_control *wbc)
--
2.9.3