[PATCH v2 1/2] kernfs: Convert to u64 id

[PATCH v2 1/2] kernfs: Convert to u64 id

[Namhyung Kim]

From: Tejun Heo <tj@kernel.org>

The kernfs_id was an union type sharing a 64bit id with 32bit ino +
gen.  But it resulted in using 32bit inode even on 64bit systems.
Also dealing with an union is annoying especially if you just want to
use a single id.

Thus let's get rid of the kernfs_node_id type and use u64 directly.
The upper 32bit is used for gen and lower is for ino on 32bit systems.
The kernfs_id_ino() and kernfs_id_gen() helpers will take care of the
bit handling depends on the system word size.

Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Martin KaFai Lau <kafai@fb.com>
Cc: Song Liu <songliubraving@fb.com>
Cc: Yonghong Song <yhs@fb.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: linux-block@vger.kernel.org
Cc: bpf@vger.kernel.org
Cc: netdev@vger.kernel.org
Signed-off-by: Tejun Heo <tj@kernel.org>
[namhyung: fix build error in bpf_get_current_cgroup_id()]
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
---
 fs/kernfs/dir.c                  | 36 ++++++++-----
 fs/kernfs/file.c                 |  4 +-
 fs/kernfs/inode.c                |  4 +-
 fs/kernfs/kernfs-internal.h      |  2 -
 fs/kernfs/mount.c                | 92 +++++++++++++++++++-------------
 include/linux/cgroup.h           | 17 +++---
 include/linux/exportfs.h         |  5 ++
 include/linux/kernfs.h           | 47 +++++++++-------
 include/trace/events/writeback.h | 92 ++++++++++++++++----------------
 kernel/bpf/helpers.c             |  2 +-
 kernel/cgroup/cgroup.c           |  5 +-
 kernel/trace/blktrace.c          | 66 +++++++++++------------
 net/core/filter.c                |  4 +-
 13 files changed, 207 insertions(+), 169 deletions(-)

diff --git a/fs/kernfs/dir.c b/fs/kernfs/dir.c
index 6ebae6bbe6a5..2beec2af809b 100644
--- a/fs/kernfs/dir.c
+++ b/fs/kernfs/dir.c
@@ -509,7 +509,7 @@ void kernfs_put(struct kernfs_node *kn)
 	struct kernfs_root *root;
 
 	/*
-	 * kernfs_node is freed with ->count 0, kernfs_find_and_get_node_by_ino
+	 * kernfs_node is freed with ->count 0, kernfs_find_and_get_node_by_id
 	 * depends on this to filter reused stale node
 	 */
 	if (!kn || !atomic_dec_and_test(&kn->count))
@@ -536,7 +536,7 @@ void kernfs_put(struct kernfs_node *kn)
 		kmem_cache_free(kernfs_iattrs_cache, kn->iattr);
 	}
 	spin_lock(&kernfs_idr_lock);
-	idr_remove(&root->ino_idr, kn->id.ino);
+	idr_remove(&root->ino_idr, (u32)kernfs_ino(kn));
 	spin_unlock(&kernfs_idr_lock);
 	kmem_cache_free(kernfs_node_cache, kn);
 
@@ -644,12 +644,12 @@ static struct kernfs_node *__kernfs_new_node(struct kernfs_root *root,
 	idr_preload_end();
 	if (ret < 0)
 		goto err_out2;
-	kn->id.ino = ret;
-	kn->id.generation = gen;
+
+	kn->id = (u64)gen << 32 | ret;
 
 	/*
 	 * set ino first. This RELEASE is paired with atomic_inc_not_zero in
-	 * kernfs_find_and_get_node_by_ino
+	 * kernfs_find_and_get_node_by_id
 	 */
 	atomic_set_release(&kn->count, 1);
 	atomic_set(&kn->active, KN_DEACTIVATED_BIAS);
@@ -680,7 +680,7 @@ static struct kernfs_node *__kernfs_new_node(struct kernfs_root *root,
 	return kn;
 
  err_out3:
-	idr_remove(&root->ino_idr, kn->id.ino);
+	idr_remove(&root->ino_idr, (u32)kernfs_ino(kn));
  err_out2:
 	kmem_cache_free(kernfs_node_cache, kn);
  err_out1:
@@ -705,20 +705,25 @@ struct kernfs_node *kernfs_new_node(struct kernfs_node *parent,
 }
 
 /*
- * kernfs_find_and_get_node_by_ino - get kernfs_node from inode number
+ * kernfs_find_and_get_node_by_id - get kernfs_node from node id
  * @root: the kernfs root
- * @ino: inode number
+ * @id: the target node id
+ *
+ * @id's lower 32bits encode ino and upper gen.  If the gen portion is
+ * zero, all generations are matched.
  *
  * RETURNS:
  * NULL on failure. Return a kernfs node with reference counter incremented
  */
-struct kernfs_node *kernfs_find_and_get_node_by_ino(struct kernfs_root *root,
-						    unsigned int ino)
+struct kernfs_node *kernfs_find_and_get_node_by_id(struct kernfs_root *root,
+						   u64 id)
 {
 	struct kernfs_node *kn;
+	ino_t ino = kernfs_id_ino(id);
+	u32 gen = kernfs_id_gen(id);
 
 	rcu_read_lock();
-	kn = idr_find(&root->ino_idr, ino);
+	kn = idr_find(&root->ino_idr, (u32)ino);
 	if (!kn)
 		goto out;
 
@@ -741,8 +746,13 @@ 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->id.ino != ino)
+	if (kernfs_ino(kn) != ino)
 		goto out;
+
+	/* if upper 32bit of @id was zero, ignore gen */
+	if (gen && kernfs_gen(kn) != gen)
+		goto out;
+
 	rcu_read_unlock();
 
 	return kn;
@@ -1678,7 +1688,7 @@ 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->id.ino;
+		ino_t ino = kernfs_ino(pos);
 
 		ctx->pos = pos->hash;
 		file->private_data = pos;
diff --git a/fs/kernfs/file.c b/fs/kernfs/file.c
index e8c792b49616..34366db3620d 100644
--- a/fs/kernfs/file.c
+++ b/fs/kernfs/file.c
@@ -892,7 +892,7 @@ 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->id.ino);
+		inode = ilookup(info->sb, kernfs_ino(kn));
 		if (!inode)
 			continue;
 
@@ -901,7 +901,7 @@ static void kernfs_notify_workfn(struct work_struct *work)
 		if (parent) {
 			struct inode *p_inode;
 
-			p_inode = ilookup(info->sb, parent->id.ino);
+			p_inode = ilookup(info->sb, kernfs_ino(parent));
 			if (p_inode) {
 				fsnotify(p_inode, FS_MODIFY | FS_EVENT_ON_CHILD,
 					 inode, FSNOTIFY_EVENT_INODE, &name, 0);
diff --git a/fs/kernfs/inode.c b/fs/kernfs/inode.c
index f3eaa8869f42..eac277c63d42 100644
--- a/fs/kernfs/inode.c
+++ b/fs/kernfs/inode.c
@@ -201,7 +201,7 @@ 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->id.generation;
+	inode->i_generation = kernfs_gen(kn);
 
 	set_default_inode_attr(inode, kn->mode);
 	kernfs_refresh_inode(kn, inode);
@@ -247,7 +247,7 @@ struct inode *kernfs_get_inode(struct super_block *sb, struct kernfs_node *kn)
 {
 	struct inode *inode;
 
-	inode = iget_locked(sb, kn->id.ino);
+	inode = iget_locked(sb, kernfs_ino(kn));
 	if (inode && (inode->i_state & I_NEW))
 		kernfs_init_inode(kn, inode);
 
diff --git a/fs/kernfs/kernfs-internal.h b/fs/kernfs/kernfs-internal.h
index 02ce570a9a3c..2f3c51d55261 100644
--- a/fs/kernfs/kernfs-internal.h
+++ b/fs/kernfs/kernfs-internal.h
@@ -109,8 +109,6 @@ struct kernfs_node *kernfs_new_node(struct kernfs_node *parent,
 				    const char *name, umode_t mode,
 				    kuid_t uid, kgid_t gid,
 				    unsigned flags);
-struct kernfs_node *kernfs_find_and_get_node_by_ino(struct kernfs_root *root,
-						    unsigned int ino);
 
 /*
  * file.c
diff --git a/fs/kernfs/mount.c b/fs/kernfs/mount.c
index 6c12fac2c287..1ac4f723c51d 100644
--- a/fs/kernfs/mount.c
+++ b/fs/kernfs/mount.c
@@ -53,63 +53,82 @@ const struct super_operations kernfs_sops = {
 	.show_path	= kernfs_sop_show_path,
 };
 
-/*
- * Similar to kernfs_fh_get_inode, this one gets kernfs node from inode
- * number and generation
- */
-struct kernfs_node *kernfs_get_node_by_id(struct kernfs_root *root,
-	const union kernfs_node_id *id)
+static int kernfs_encode_fh(struct inode *inode, __u32 *fh, int *max_len,
+			    struct inode *parent)
 {
-	struct kernfs_node *kn;
+	struct kernfs_node *kn = inode->i_private;
 
-	kn = kernfs_find_and_get_node_by_ino(root, id->ino);
-	if (!kn)
-		return NULL;
-	if (kn->id.generation != id->generation) {
-		kernfs_put(kn);
-		return NULL;
+	if (*max_len < 2) {
+		*max_len = 2;
+		return FILEID_INVALID;
 	}
-	return kn;
+
+	*max_len = 2;
+	*(u64 *)fh = kn->id;
+	return FILEID_KERNFS;
 }
 
-static struct inode *kernfs_fh_get_inode(struct super_block *sb,
-		u64 ino, u32 generation)
+static struct dentry *__kernfs_fh_to_dentry(struct super_block *sb,
+					    struct fid *fid, int fh_len,
+					    int fh_type, bool get_parent)
 {
 	struct kernfs_super_info *info = kernfs_info(sb);
-	struct inode *inode;
 	struct kernfs_node *kn;
+	struct inode *inode;
+	u64 id;
 
-	if (ino == 0)
-		return ERR_PTR(-ESTALE);
+	if (fh_len < 2)
+		return NULL;
 
-	kn = kernfs_find_and_get_node_by_ino(info->root, ino);
+	/*
+	 * We used to use the generic types and blktrace exposes the
+	 * numbers without specifying the type.  Accept the generic types
+	 * for compatibility.
+	 */
+	switch (fh_type) {
+	case FILEID_KERNFS:
+		id = *(u64 *)fid;
+		break;
+	case FILEID_INO32_GEN:
+	case FILEID_INO32_GEN_PARENT:
+		id = ((u64)fid->i32.gen << 32) | fid->i32.ino;
+		break;
+	default:
+		return NULL;
+	}
+
+	kn = kernfs_find_and_get_node_by_id(info->root, id);
 	if (!kn)
 		return ERR_PTR(-ESTALE);
+
+	if (get_parent) {
+		struct kernfs_node *parent;
+
+		parent = kernfs_get_parent(kn);
+		kernfs_put(kn);
+		kn = parent;
+	}
+
 	inode = kernfs_get_inode(sb, kn);
 	kernfs_put(kn);
 	if (!inode)
 		return ERR_PTR(-ESTALE);
 
-	if (generation && inode->i_generation != generation) {
-		/* we didn't find the right inode.. */
-		iput(inode);
-		return ERR_PTR(-ESTALE);
-	}
-	return inode;
+	return d_obtain_alias(inode);
 }
 
-static struct dentry *kernfs_fh_to_dentry(struct super_block *sb, struct fid *fid,
-		int fh_len, int fh_type)
+static struct dentry *kernfs_fh_to_dentry(struct super_block *sb,
+					  struct fid *fid, int fh_len,
+					  int fh_type)
 {
-	return generic_fh_to_dentry(sb, fid, fh_len, fh_type,
-				    kernfs_fh_get_inode);
+	return __kernfs_fh_to_dentry(sb, fid, fh_len, fh_type, false);
 }
 
-static struct dentry *kernfs_fh_to_parent(struct super_block *sb, struct fid *fid,
-		int fh_len, int fh_type)
+static struct dentry *kernfs_fh_to_parent(struct super_block *sb,
+					  struct fid *fid, int fh_len,
+					  int fh_type)
 {
-	return generic_fh_to_parent(sb, fid, fh_len, fh_type,
-				    kernfs_fh_get_inode);
+	return __kernfs_fh_to_dentry(sb, fid, fh_len, fh_type, true);
 }
 
 static struct dentry *kernfs_get_parent_dentry(struct dentry *child)
@@ -120,6 +139,7 @@ static struct dentry *kernfs_get_parent_dentry(struct dentry *child)
 }
 
 static const struct export_operations kernfs_export_ops = {
+	.encode_fh	= kernfs_encode_fh,
 	.fh_to_dentry	= kernfs_fh_to_dentry,
 	.fh_to_parent	= kernfs_fh_to_parent,
 	.get_parent	= kernfs_get_parent_dentry,
@@ -365,9 +385,9 @@ void __init kernfs_init(void)
 {
 
 	/*
-	 * the slab is freed in RCU context, so kernfs_find_and_get_node_by_ino
+	 * the slab is freed in RCU context, so kernfs_find_and_get_node_by_id
 	 * can access the slab lock free. This could introduce stale nodes,
-	 * please see how kernfs_find_and_get_node_by_ino filters out stale
+	 * please see how kernfs_find_and_get_node_by_id filters out stale
 	 * nodes.
 	 */
 	kernfs_node_cache = kmem_cache_create("kernfs_node_cache",
diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
index f6b048902d6c..4b08a354039c 100644
--- a/include/linux/cgroup.h
+++ b/include/linux/cgroup.h
@@ -616,7 +616,7 @@ 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->id.ino;
+	return kernfs_ino(cgrp->kn);
 }
 
 /* cft/css accessors for cftype->write() operation */
@@ -687,13 +687,12 @@ static inline void cgroup_kthread_ready(void)
 	current->no_cgroup_migration = 0;
 }
 
-static inline union kernfs_node_id *cgroup_get_kernfs_id(struct cgroup *cgrp)
+static inline u64 cgroup_get_kernfs_id(struct cgroup *cgrp)
 {
-	return &cgrp->kn->id;
+	return cgrp->kn->id;
 }
 
-void cgroup_path_from_kernfs_id(const union kernfs_node_id *id,
-					char *buf, size_t buflen);
+void cgroup_path_from_kernfs_id(u64 id, char *buf, size_t buflen);
 #else /* !CONFIG_CGROUPS */
 
 struct cgroup_subsys_state;
@@ -718,9 +717,9 @@ static inline int cgroup_init_early(void) { return 0; }
 static inline int cgroup_init(void) { return 0; }
 static inline void cgroup_init_kthreadd(void) {}
 static inline void cgroup_kthread_ready(void) {}
-static inline union kernfs_node_id *cgroup_get_kernfs_id(struct cgroup *cgrp)
+static inline u64 cgroup_get_kernfs_id(struct cgroup *cgrp)
 {
-	return NULL;
+	return 0;
 }
 
 static inline struct cgroup *cgroup_parent(struct cgroup *cgrp)
@@ -739,8 +738,8 @@ static inline bool task_under_cgroup_hierarchy(struct task_struct *task,
 	return true;
 }
 
-static inline void cgroup_path_from_kernfs_id(const union kernfs_node_id *id,
-	char *buf, size_t buflen) {}
+static inline void cgroup_path_from_kernfs_id(u64 id, char *buf, size_t buflen)
+{}
 #endif /* !CONFIG_CGROUPS */
 
 #ifdef CONFIG_CGROUPS
diff --git a/include/linux/exportfs.h b/include/linux/exportfs.h
index cf6571fc9c01..d896b8657085 100644
--- a/include/linux/exportfs.h
+++ b/include/linux/exportfs.h
@@ -104,6 +104,11 @@ enum fid_type {
 	 */
 	FILEID_LUSTRE = 0x97,
 
+	/*
+	 * 64 bit unique kernfs id
+	 */
+	FILEID_KERNFS = 0xfe,
+
 	/*
 	 * Filesystems must not use 0xff file ID.
 	 */
diff --git a/include/linux/kernfs.h b/include/linux/kernfs.h
index 936b61bd504e..0edbc2b8865c 100644
--- a/include/linux/kernfs.h
+++ b/include/linux/kernfs.h
@@ -104,21 +104,6 @@ struct kernfs_elem_attr {
 	struct kernfs_node	*notify_next;	/* for kernfs_notify() */
 };
 
-/* represent a kernfs node */
-union kernfs_node_id {
-	struct {
-		/*
-		 * blktrace will export this struct as a simplified 'struct
-		 * fid' (which is a big data struction), so userspace can use
-		 * it to find kernfs node. The layout must match the first two
-		 * fields of 'struct fid' exactly.
-		 */
-		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
@@ -155,7 +140,7 @@ struct kernfs_node {
 
 	void			*priv;
 
-	union kernfs_node_id	id;
+	u64			id;
 	unsigned short		flags;
 	umode_t			mode;
 	struct kernfs_iattrs	*iattr;
@@ -291,6 +276,32 @@ static inline enum kernfs_node_type kernfs_type(struct kernfs_node *kn)
 	return kn->flags & KERNFS_TYPE_MASK;
 }
 
+static inline ino_t kernfs_id_ino(u64 id)
+{
+	if (sizeof(ino_t) >= sizeof(u64))
+		return id;
+	else
+		return (u32)id;
+}
+
+static inline u32 kernfs_id_gen(u64 id)
+{
+	if (sizeof(ino_t) >= sizeof(u64))
+		return 0;
+	else
+		return id >> 32;
+}
+
+static inline ino_t kernfs_ino(struct kernfs_node *kn)
+{
+	return kernfs_id_ino(kn->id);
+}
+
+static inline ino_t kernfs_gen(struct kernfs_node *kn)
+{
+	return kernfs_id_gen(kn->id);
+}
+
 /**
  * kernfs_enable_ns - enable namespace under a directory
  * @kn: directory of interest, should be empty
@@ -382,8 +393,8 @@ void kernfs_kill_sb(struct super_block *sb);
 
 void kernfs_init(void);
 
-struct kernfs_node *kernfs_get_node_by_id(struct kernfs_root *root,
-	const union kernfs_node_id *id);
+struct kernfs_node *kernfs_find_and_get_node_by_id(struct kernfs_root *root,
+						   u64 id);
 #else	/* CONFIG_KERNFS */
 
 static inline enum kernfs_node_type kernfs_type(struct kernfs_node *kn)
diff --git a/include/trace/events/writeback.h b/include/trace/events/writeback.h
index c2ce6480b4b1..3eef363932c9 100644
--- a/include/trace/events/writeback.h
+++ b/include/trace/events/writeback.h
@@ -61,7 +61,7 @@ DECLARE_EVENT_CLASS(writeback_page_template,
 
 	TP_STRUCT__entry (
 		__array(char, name, 32)
-		__field(unsigned long, ino)
+		__field(ino_t, ino)
 		__field(pgoff_t, index)
 	),
 
@@ -102,7 +102,7 @@ DECLARE_EVENT_CLASS(writeback_dirty_inode_template,
 
 	TP_STRUCT__entry (
 		__array(char, name, 32)
-		__field(unsigned long, ino)
+		__field(ino_t, ino)
 		__field(unsigned long, state)
 		__field(unsigned long, flags)
 	),
@@ -150,28 +150,28 @@ DEFINE_EVENT(writeback_dirty_inode_template, writeback_dirty_inode,
 #ifdef CREATE_TRACE_POINTS
 #ifdef CONFIG_CGROUP_WRITEBACK
 
-static inline unsigned int __trace_wb_assign_cgroup(struct bdi_writeback *wb)
+static inline ino_t __trace_wb_assign_cgroup(struct bdi_writeback *wb)
 {
-	return wb->memcg_css->cgroup->kn->id.ino;
+	return cgroup_ino(wb->memcg_css->cgroup);
 }
 
-static inline unsigned int __trace_wbc_assign_cgroup(struct writeback_control *wbc)
+static inline ino_t __trace_wbc_assign_cgroup(struct writeback_control *wbc)
 {
 	if (wbc->wb)
 		return __trace_wb_assign_cgroup(wbc->wb);
 	else
-		return -1U;
+		return 0;
 }
 #else	/* CONFIG_CGROUP_WRITEBACK */
 
-static inline unsigned int __trace_wb_assign_cgroup(struct bdi_writeback *wb)
+static inline ino_t __trace_wb_assign_cgroup(struct bdi_writeback *wb)
 {
-	return -1U;
+	return 0;
 }
 
-static inline unsigned int __trace_wbc_assign_cgroup(struct writeback_control *wbc)
+static inline ino_t __trace_wbc_assign_cgroup(struct writeback_control *wbc)
 {
-	return -1U;
+	return 0;
 }
 
 #endif	/* CONFIG_CGROUP_WRITEBACK */
@@ -187,8 +187,8 @@ TRACE_EVENT(inode_foreign_history,
 
 	TP_STRUCT__entry(
 		__array(char,		name, 32)
-		__field(unsigned long,	ino)
-		__field(unsigned int,	cgroup_ino)
+		__field(ino_t,		ino)
+		__field(ino_t,		cgroup_ino)
 		__field(unsigned int,	history)
 	),
 
@@ -199,7 +199,7 @@ TRACE_EVENT(inode_foreign_history,
 		__entry->history	= history;
 	),
 
-	TP_printk("bdi %s: ino=%lu cgroup_ino=%u history=0x%x",
+	TP_printk("bdi %s: ino=%lu cgroup_ino=%lu history=0x%x",
 		__entry->name,
 		__entry->ino,
 		__entry->cgroup_ino,
@@ -216,9 +216,9 @@ TRACE_EVENT(inode_switch_wbs,
 
 	TP_STRUCT__entry(
 		__array(char,		name, 32)
-		__field(unsigned long,	ino)
-		__field(unsigned int,	old_cgroup_ino)
-		__field(unsigned int,	new_cgroup_ino)
+		__field(ino_t,		ino)
+		__field(ino_t,		old_cgroup_ino)
+		__field(ino_t,		new_cgroup_ino)
 	),
 
 	TP_fast_assign(
@@ -228,7 +228,7 @@ TRACE_EVENT(inode_switch_wbs,
 		__entry->new_cgroup_ino	= __trace_wb_assign_cgroup(new_wb);
 	),
 
-	TP_printk("bdi %s: ino=%lu old_cgroup_ino=%u new_cgroup_ino=%u",
+	TP_printk("bdi %s: ino=%lu old_cgroup_ino=%lu new_cgroup_ino=%lu",
 		__entry->name,
 		__entry->ino,
 		__entry->old_cgroup_ino,
@@ -245,10 +245,10 @@ TRACE_EVENT(track_foreign_dirty,
 	TP_STRUCT__entry(
 		__array(char,		name, 32)
 		__field(u64,		bdi_id)
-		__field(unsigned long,	ino)
+		__field(ino_t,		ino)
 		__field(unsigned int,	memcg_id)
-		__field(unsigned int,	cgroup_ino)
-		__field(unsigned int,	page_cgroup_ino)
+		__field(ino_t,		cgroup_ino)
+		__field(ino_t,		page_cgroup_ino)
 	),
 
 	TP_fast_assign(
@@ -260,10 +260,10 @@ TRACE_EVENT(track_foreign_dirty,
 		__entry->ino		= inode ? inode->i_ino : 0;
 		__entry->memcg_id	= wb->memcg_css->id;
 		__entry->cgroup_ino	= __trace_wb_assign_cgroup(wb);
-		__entry->page_cgroup_ino = page->mem_cgroup->css.cgroup->kn->id.ino;
+		__entry->page_cgroup_ino = cgroup_ino(page->mem_cgroup->css.cgroup);
 	),
 
-	TP_printk("bdi %s[%llu]: ino=%lu memcg_id=%u cgroup_ino=%u page_cgroup_ino=%u",
+	TP_printk("bdi %s[%llu]: ino=%lu memcg_id=%u cgroup_ino=%lu page_cgroup_ino=%lu",
 		__entry->name,
 		__entry->bdi_id,
 		__entry->ino,
@@ -282,7 +282,7 @@ TRACE_EVENT(flush_foreign,
 
 	TP_STRUCT__entry(
 		__array(char,		name, 32)
-		__field(unsigned int,	cgroup_ino)
+		__field(ino_t,		cgroup_ino)
 		__field(unsigned int,	frn_bdi_id)
 		__field(unsigned int,	frn_memcg_id)
 	),
@@ -294,7 +294,7 @@ TRACE_EVENT(flush_foreign,
 		__entry->frn_memcg_id	= frn_memcg_id;
 	),
 
-	TP_printk("bdi %s: cgroup_ino=%u frn_bdi_id=%u frn_memcg_id=%u",
+	TP_printk("bdi %s: cgroup_ino=%lu frn_bdi_id=%u frn_memcg_id=%u",
 		__entry->name,
 		__entry->cgroup_ino,
 		__entry->frn_bdi_id,
@@ -311,9 +311,9 @@ DECLARE_EVENT_CLASS(writeback_write_inode_template,
 
 	TP_STRUCT__entry (
 		__array(char, name, 32)
-		__field(unsigned long, ino)
+		__field(ino_t, ino)
 		__field(int, sync_mode)
-		__field(unsigned int, cgroup_ino)
+		__field(ino_t, cgroup_ino)
 	),
 
 	TP_fast_assign(
@@ -324,7 +324,7 @@ DECLARE_EVENT_CLASS(writeback_write_inode_template,
 		__entry->cgroup_ino	= __trace_wbc_assign_cgroup(wbc);
 	),
 
-	TP_printk("bdi %s: ino=%lu sync_mode=%d cgroup_ino=%u",
+	TP_printk("bdi %s: ino=%lu sync_mode=%d cgroup_ino=%lu",
 		__entry->name,
 		__entry->ino,
 		__entry->sync_mode,
@@ -358,7 +358,7 @@ DECLARE_EVENT_CLASS(writeback_work_class,
 		__field(int, range_cyclic)
 		__field(int, for_background)
 		__field(int, reason)
-		__field(unsigned int, cgroup_ino)
+		__field(ino_t, cgroup_ino)
 	),
 	TP_fast_assign(
 		strscpy_pad(__entry->name,
@@ -374,7 +374,7 @@ DECLARE_EVENT_CLASS(writeback_work_class,
 		__entry->cgroup_ino = __trace_wb_assign_cgroup(wb);
 	),
 	TP_printk("bdi %s: sb_dev %d:%d nr_pages=%ld sync_mode=%d "
-		  "kupdate=%d range_cyclic=%d background=%d reason=%s cgroup_ino=%u",
+		  "kupdate=%d range_cyclic=%d background=%d reason=%s cgroup_ino=%lu",
 		  __entry->name,
 		  MAJOR(__entry->sb_dev), MINOR(__entry->sb_dev),
 		  __entry->nr_pages,
@@ -413,13 +413,13 @@ DECLARE_EVENT_CLASS(writeback_class,
 	TP_ARGS(wb),
 	TP_STRUCT__entry(
 		__array(char, name, 32)
-		__field(unsigned int, cgroup_ino)
+		__field(ino_t, cgroup_ino)
 	),
 	TP_fast_assign(
 		strscpy_pad(__entry->name, dev_name(wb->bdi->dev), 32);
 		__entry->cgroup_ino = __trace_wb_assign_cgroup(wb);
 	),
-	TP_printk("bdi %s: cgroup_ino=%u",
+	TP_printk("bdi %s: cgroup_ino=%lu",
 		  __entry->name,
 		  __entry->cgroup_ino
 	)
@@ -459,7 +459,7 @@ DECLARE_EVENT_CLASS(wbc_class,
 		__field(int, range_cyclic)
 		__field(long, range_start)
 		__field(long, range_end)
-		__field(unsigned int, cgroup_ino)
+		__field(ino_t, cgroup_ino)
 	),
 
 	TP_fast_assign(
@@ -478,7 +478,7 @@ DECLARE_EVENT_CLASS(wbc_class,
 
 	TP_printk("bdi %s: towrt=%ld skip=%ld mode=%d kupd=%d "
 		"bgrd=%d reclm=%d cyclic=%d "
-		"start=0x%lx end=0x%lx cgroup_ino=%u",
+		"start=0x%lx end=0x%lx cgroup_ino=%lu",
 		__entry->name,
 		__entry->nr_to_write,
 		__entry->pages_skipped,
@@ -510,7 +510,7 @@ TRACE_EVENT(writeback_queue_io,
 		__field(long,		age)
 		__field(int,		moved)
 		__field(int,		reason)
-		__field(unsigned int,	cgroup_ino)
+		__field(ino_t,		cgroup_ino)
 	),
 	TP_fast_assign(
 		unsigned long *older_than_this = work->older_than_this;
@@ -522,7 +522,7 @@ TRACE_EVENT(writeback_queue_io,
 		__entry->reason	= work->reason;
 		__entry->cgroup_ino	= __trace_wb_assign_cgroup(wb);
 	),
-	TP_printk("bdi %s: older=%lu age=%ld enqueue=%d reason=%s cgroup_ino=%u",
+	TP_printk("bdi %s: older=%lu age=%ld enqueue=%d reason=%s cgroup_ino=%lu",
 		__entry->name,
 		__entry->older,	/* older_than_this in jiffies */
 		__entry->age,	/* older_than_this in relative milliseconds */
@@ -596,7 +596,7 @@ TRACE_EVENT(bdi_dirty_ratelimit,
 		__field(unsigned long,	dirty_ratelimit)
 		__field(unsigned long,	task_ratelimit)
 		__field(unsigned long,	balanced_dirty_ratelimit)
-		__field(unsigned int,	cgroup_ino)
+		__field(ino_t,		cgroup_ino)
 	),
 
 	TP_fast_assign(
@@ -614,7 +614,7 @@ TRACE_EVENT(bdi_dirty_ratelimit,
 	TP_printk("bdi %s: "
 		  "write_bw=%lu awrite_bw=%lu dirty_rate=%lu "
 		  "dirty_ratelimit=%lu task_ratelimit=%lu "
-		  "balanced_dirty_ratelimit=%lu cgroup_ino=%u",
+		  "balanced_dirty_ratelimit=%lu cgroup_ino=%lu",
 		  __entry->bdi,
 		  __entry->write_bw,		/* write bandwidth */
 		  __entry->avg_write_bw,	/* avg write bandwidth */
@@ -660,7 +660,7 @@ TRACE_EVENT(balance_dirty_pages,
 		__field(	 long,	pause)
 		__field(unsigned long,	period)
 		__field(	 long,	think)
-		__field(unsigned int,	cgroup_ino)
+		__field(ino_t,		cgroup_ino)
 	),
 
 	TP_fast_assign(
@@ -692,7 +692,7 @@ TRACE_EVENT(balance_dirty_pages,
 		  "bdi_setpoint=%lu bdi_dirty=%lu "
 		  "dirty_ratelimit=%lu task_ratelimit=%lu "
 		  "dirtied=%u dirtied_pause=%u "
-		  "paused=%lu pause=%ld period=%lu think=%ld cgroup_ino=%u",
+		  "paused=%lu pause=%ld period=%lu think=%ld cgroup_ino=%lu",
 		  __entry->bdi,
 		  __entry->limit,
 		  __entry->setpoint,
@@ -718,10 +718,10 @@ TRACE_EVENT(writeback_sb_inodes_requeue,
 
 	TP_STRUCT__entry(
 		__array(char, name, 32)
-		__field(unsigned long, ino)
+		__field(ino_t, ino)
 		__field(unsigned long, state)
 		__field(unsigned long, dirtied_when)
-		__field(unsigned int, cgroup_ino)
+		__field(ino_t, cgroup_ino)
 	),
 
 	TP_fast_assign(
@@ -733,7 +733,7 @@ TRACE_EVENT(writeback_sb_inodes_requeue,
 		__entry->cgroup_ino	= __trace_wb_assign_cgroup(inode_to_wb(inode));
 	),
 
-	TP_printk("bdi %s: ino=%lu state=%s dirtied_when=%lu age=%lu cgroup_ino=%u",
+	TP_printk("bdi %s: ino=%lu state=%s dirtied_when=%lu age=%lu cgroup_ino=%lu",
 		  __entry->name,
 		  __entry->ino,
 		  show_inode_state(__entry->state),
@@ -789,13 +789,13 @@ DECLARE_EVENT_CLASS(writeback_single_inode_template,
 
 	TP_STRUCT__entry(
 		__array(char, name, 32)
-		__field(unsigned long, ino)
+		__field(ino_t, ino)
 		__field(unsigned long, state)
 		__field(unsigned long, dirtied_when)
 		__field(unsigned long, writeback_index)
 		__field(long, nr_to_write)
 		__field(unsigned long, wrote)
-		__field(unsigned int, cgroup_ino)
+		__field(ino_t, cgroup_ino)
 	),
 
 	TP_fast_assign(
@@ -811,7 +811,7 @@ DECLARE_EVENT_CLASS(writeback_single_inode_template,
 	),
 
 	TP_printk("bdi %s: ino=%lu state=%s dirtied_when=%lu age=%lu "
-		  "index=%lu to_write=%ld wrote=%lu cgroup_ino=%u",
+		  "index=%lu to_write=%ld wrote=%lu cgroup_ino=%lu",
 		  __entry->name,
 		  __entry->ino,
 		  show_inode_state(__entry->state),
@@ -845,7 +845,7 @@ DECLARE_EVENT_CLASS(writeback_inode_template,
 
 	TP_STRUCT__entry(
 		__field(	dev_t,	dev			)
-		__field(unsigned long,	ino			)
+		__field(	ino_t,	ino			)
 		__field(unsigned long,	state			)
 		__field(	__u16, mode			)
 		__field(unsigned long, dirtied_when		)
diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c
index 5e28718928ca..912e761cd17a 100644
--- a/kernel/bpf/helpers.c
+++ b/kernel/bpf/helpers.c
@@ -317,7 +317,7 @@ BPF_CALL_0(bpf_get_current_cgroup_id)
 {
 	struct cgroup *cgrp = task_dfl_cgroup(current);
 
-	return cgrp->kn->id.id;
+	return cgrp->kn->id;
 }
 
 const struct bpf_func_proto bpf_get_current_cgroup_id_proto = {
diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c
index cf32c0c7a45d..b5dcbee5aa6c 100644
--- a/kernel/cgroup/cgroup.c
+++ b/kernel/cgroup/cgroup.c
@@ -5786,12 +5786,11 @@ static int __init cgroup_wq_init(void)
 }
 core_initcall(cgroup_wq_init);
 
-void cgroup_path_from_kernfs_id(const union kernfs_node_id *id,
-					char *buf, size_t buflen)
+void cgroup_path_from_kernfs_id(u64 id, char *buf, size_t buflen)
 {
 	struct kernfs_node *kn;
 
-	kn = kernfs_get_node_by_id(cgrp_dfl_root.kf_root, id);
+	kn = kernfs_find_and_get_node_by_id(cgrp_dfl_root.kf_root, id);
 	if (!kn)
 		return;
 	kernfs_path(kn, buf, buflen);
diff --git a/kernel/trace/blktrace.c b/kernel/trace/blktrace.c
index 2d6e93ab0478..53d259578175 100644
--- a/kernel/trace/blktrace.c
+++ b/kernel/trace/blktrace.c
@@ -64,8 +64,7 @@ static void blk_unregister_tracepoints(void);
  * Send out a notify message.
  */
 static void trace_note(struct blk_trace *bt, pid_t pid, int action,
-		       const void *data, size_t len,
-		       union kernfs_node_id *cgid)
+		       const void *data, size_t len, u64 cgid)
 {
 	struct blk_io_trace *t;
 	struct ring_buffer_event *event = NULL;
@@ -73,7 +72,7 @@ static void trace_note(struct blk_trace *bt, pid_t pid, int action,
 	int pc = 0;
 	int cpu = smp_processor_id();
 	bool blk_tracer = blk_tracer_enabled;
-	ssize_t cgid_len = cgid ? sizeof(*cgid) : 0;
+	ssize_t cgid_len = cgid ? sizeof(cgid) : 0;
 
 	if (blk_tracer) {
 		buffer = blk_tr->trace_buffer.buffer;
@@ -100,9 +99,9 @@ static void trace_note(struct blk_trace *bt, pid_t pid, int action,
 		t->pid = pid;
 		t->cpu = cpu;
 		t->pdu_len = len + cgid_len;
-		if (cgid)
-			memcpy((void *)t + sizeof(*t), cgid, cgid_len);
-		memcpy((void *) t + sizeof(*t) + cgid_len, data, len);
+		if (cgid_len)
+			*(u64 *)(t + 1) = cgid;
+		memcpy((void *)( t + sizeof(*t)) + cgid_len, data, len);
 
 		if (blk_tracer)
 			trace_buffer_unlock_commit(blk_tr, buffer, event, 0, pc);
@@ -122,7 +121,7 @@ static void trace_note_tsk(struct task_struct *tsk)
 	spin_lock_irqsave(&running_trace_lock, flags);
 	list_for_each_entry(bt, &running_trace_list, running_list) {
 		trace_note(bt, tsk->pid, BLK_TN_PROCESS, tsk->comm,
-			   sizeof(tsk->comm), NULL);
+			   sizeof(tsk->comm), 0);
 	}
 	spin_unlock_irqrestore(&running_trace_lock, flags);
 }
@@ -139,7 +138,7 @@ static void trace_note_time(struct blk_trace *bt)
 	words[1] = now.tv_nsec;
 
 	local_irq_save(flags);
-	trace_note(bt, 0, BLK_TN_TIMESTAMP, words, sizeof(words), NULL);
+	trace_note(bt, 0, BLK_TN_TIMESTAMP, words, sizeof(words), 0);
 	local_irq_restore(flags);
 }
 
@@ -172,9 +171,9 @@ void __trace_note_message(struct blk_trace *bt, struct blkcg *blkcg,
 		blkcg = NULL;
 #ifdef CONFIG_BLK_CGROUP
 	trace_note(bt, 0, BLK_TN_MESSAGE, buf, n,
-		blkcg ? cgroup_get_kernfs_id(blkcg->css.cgroup) : NULL);
+		blkcg ? cgroup_get_kernfs_id(blkcg->css.cgroup) : 0);
 #else
-	trace_note(bt, 0, BLK_TN_MESSAGE, buf, n, NULL);
+	trace_note(bt, 0, BLK_TN_MESSAGE, buf, n, 0);
 #endif
 	local_irq_restore(flags);
 }
@@ -212,7 +211,7 @@ static const u32 ddir_act[2] = { BLK_TC_ACT(BLK_TC_READ),
  */
 static void __blk_add_trace(struct blk_trace *bt, sector_t sector, int bytes,
 		     int op, int op_flags, u32 what, int error, int pdu_len,
-		     void *pdu_data, union kernfs_node_id *cgid)
+		     void *pdu_data, u64 cgid)
 {
 	struct task_struct *tsk = current;
 	struct ring_buffer_event *event = NULL;
@@ -223,7 +222,7 @@ static void __blk_add_trace(struct blk_trace *bt, sector_t sector, int bytes,
 	pid_t pid;
 	int cpu, pc = 0;
 	bool blk_tracer = blk_tracer_enabled;
-	ssize_t cgid_len = cgid ? sizeof(*cgid) : 0;
+	ssize_t cgid_len = cgid ? sizeof(cgid) : 0;
 
 	if (unlikely(bt->trace_state != Blktrace_running && !blk_tracer))
 		return;
@@ -294,7 +293,7 @@ static void __blk_add_trace(struct blk_trace *bt, sector_t sector, int bytes,
 		t->pdu_len = pdu_len + cgid_len;
 
 		if (cgid_len)
-			memcpy((void *)t + sizeof(*t), cgid, cgid_len);
+			*(u64 *)(t + 1) = cgid;
 		if (pdu_len)
 			memcpy((void *)t + sizeof(*t) + cgid_len, pdu_data, pdu_len);
 
@@ -751,31 +750,29 @@ void blk_trace_shutdown(struct request_queue *q)
 }
 
 #ifdef CONFIG_BLK_CGROUP
-static union kernfs_node_id *
-blk_trace_bio_get_cgid(struct request_queue *q, struct bio *bio)
+static u64 blk_trace_bio_get_cgid(struct request_queue *q, struct bio *bio)
 {
 	struct blk_trace *bt = q->blk_trace;
 
 	if (!bt || !(blk_tracer_flags.val & TRACE_BLK_OPT_CGROUP))
-		return NULL;
+		return 0;
 
 	if (!bio->bi_blkg)
-		return NULL;
+		return 0;
 	return cgroup_get_kernfs_id(bio_blkcg(bio)->css.cgroup);
 }
 #else
-static union kernfs_node_id *
-blk_trace_bio_get_cgid(struct request_queue *q, struct bio *bio)
+u64 blk_trace_bio_get_cgid(struct request_queue *q, struct bio *bio)
 {
-	return NULL;
+	return 0;
 }
 #endif
 
-static union kernfs_node_id *
+static u64
 blk_trace_request_get_cgid(struct request_queue *q, struct request *rq)
 {
 	if (!rq->bio)
-		return NULL;
+		return 0;
 	/* Use the first bio */
 	return blk_trace_bio_get_cgid(q, rq->bio);
 }
@@ -797,8 +794,7 @@ blk_trace_request_get_cgid(struct request_queue *q, struct request *rq)
  *
  **/
 static void blk_add_trace_rq(struct request *rq, int error,
-			     unsigned int nr_bytes, u32 what,
-			     union kernfs_node_id *cgid)
+			     unsigned int nr_bytes, u32 what, u64 cgid)
 {
 	struct blk_trace *bt = rq->q->blk_trace;
 
@@ -913,7 +909,7 @@ static void blk_add_trace_getrq(void *ignore,
 
 		if (bt)
 			__blk_add_trace(bt, 0, 0, rw, 0, BLK_TA_GETRQ, 0, 0,
-					NULL, NULL);
+					NULL, 0);
 	}
 }
 
@@ -929,7 +925,7 @@ static void blk_add_trace_sleeprq(void *ignore,
 
 		if (bt)
 			__blk_add_trace(bt, 0, 0, rw, 0, BLK_TA_SLEEPRQ,
-					0, 0, NULL, NULL);
+					0, 0, NULL, 0);
 	}
 }
 
@@ -938,7 +934,7 @@ static void blk_add_trace_plug(void *ignore, struct request_queue *q)
 	struct blk_trace *bt = q->blk_trace;
 
 	if (bt)
-		__blk_add_trace(bt, 0, 0, 0, 0, BLK_TA_PLUG, 0, 0, NULL, NULL);
+		__blk_add_trace(bt, 0, 0, 0, 0, BLK_TA_PLUG, 0, 0, NULL, 0);
 }
 
 static void blk_add_trace_unplug(void *ignore, struct request_queue *q,
@@ -955,7 +951,7 @@ static void blk_add_trace_unplug(void *ignore, struct request_queue *q,
 		else
 			what = BLK_TA_UNPLUG_TIMER;
 
-		__blk_add_trace(bt, 0, 0, 0, 0, what, 0, sizeof(rpdu), &rpdu, NULL);
+		__blk_add_trace(bt, 0, 0, 0, 0, what, 0, sizeof(rpdu), &rpdu, 0);
 	}
 }
 
@@ -1173,18 +1169,18 @@ const struct blk_io_trace *te_blk_io_trace(const struct trace_entry *ent)
 static inline const void *pdu_start(const struct trace_entry *ent, bool has_cg)
 {
 	return (void *)(te_blk_io_trace(ent) + 1) +
-		(has_cg ? sizeof(union kernfs_node_id) : 0);
+		(has_cg ? sizeof(u64) : 0);
 }
 
-static inline const void *cgid_start(const struct trace_entry *ent)
+static inline u64 t_cgid(const struct trace_entry *ent)
 {
-	return (void *)(te_blk_io_trace(ent) + 1);
+	return *(u64 *)(te_blk_io_trace(ent) + 1);
 }
 
 static inline int pdu_real_len(const struct trace_entry *ent, bool has_cg)
 {
 	return te_blk_io_trace(ent)->pdu_len -
-			(has_cg ? sizeof(union kernfs_node_id) : 0);
+			(has_cg ? sizeof(u64) : 0);
 }
 
 static inline u32 t_action(const struct trace_entry *ent)
@@ -1257,7 +1253,7 @@ static void blk_log_action(struct trace_iterator *iter, const char *act,
 
 	fill_rwbs(rwbs, t);
 	if (has_cg) {
-		const union kernfs_node_id *id = cgid_start(iter->ent);
+		u64 id = t_cgid(iter->ent);
 
 		if (blk_tracer_flags.val & TRACE_BLK_OPT_CGNAME) {
 			char blkcg_name_buf[NAME_MAX + 1] = "<...>";
@@ -1269,9 +1265,9 @@ static void blk_log_action(struct trace_iterator *iter, const char *act,
 				 blkcg_name_buf, act, rwbs);
 		} else
 			trace_seq_printf(&iter->seq,
-				 "%3d,%-3d %x,%-x %2s %3s ",
+				 "%3d,%-3d %llx,%-llx %2s %3s ",
 				 MAJOR(t->device), MINOR(t->device),
-				 id->ino, id->generation, act, rwbs);
+				 id & U32_MAX, id >> 32, act, rwbs);
 	} else
 		trace_seq_printf(&iter->seq, "%3d,%-3d %2s %3s ",
 				 MAJOR(t->device), MINOR(t->device), act, rwbs);
diff --git a/net/core/filter.c b/net/core/filter.c
index ed6563622ce3..b360a7beb6fc 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -4089,7 +4089,7 @@ BPF_CALL_1(bpf_skb_cgroup_id, const struct sk_buff *, skb)
 		return 0;
 
 	cgrp = sock_cgroup_ptr(&sk->sk_cgrp_data);
-	return cgrp->kn->id.id;
+	return cgrp->kn->id;
 }
 
 static const struct bpf_func_proto bpf_skb_cgroup_id_proto = {
@@ -4114,7 +4114,7 @@ BPF_CALL_2(bpf_skb_ancestor_cgroup_id, const struct sk_buff *, skb, int,
 	if (!ancestor)
 		return 0;
 
-	return ancestor->kn->id.id;
+	return ancestor->kn->id;
 }
 
 static const struct bpf_func_proto bpf_skb_ancestor_cgroup_id_proto = {
-- 
2.24.0.rc1.363.gb1bccd3e3d-goog

Re: [PATCH v2 1/2] kernfs: Convert to u64 id

[Steven Rostedt]

On Mon,  4 Nov 2019 17:45:19 +0900
Namhyung Kim <namhyung@kernel.org> wrote:

> From: Tejun Heo <tj@kernel.org>
> 
> The kernfs_id was an union type sharing a 64bit id with 32bit ino +
> gen.  But it resulted in using 32bit inode even on 64bit systems.
> Also dealing with an union is annoying especially if you just want to
> use a single id.
> 
> Thus let's get rid of the kernfs_node_id type and use u64 directly.
> The upper 32bit is used for gen and lower is for ino on 32bit systems.
> The kernfs_id_ino() and kernfs_id_gen() helpers will take care of the
> bit handling depends on the system word size.
> 
> Cc: Steven Rostedt <rostedt@goodmis.org>
> Cc: Ingo Molnar <mingo@redhat.com>
> Cc: Alexei Starovoitov <ast@kernel.org>
> Cc: Daniel Borkmann <daniel@iogearbox.net>
> Cc: Martin KaFai Lau <kafai@fb.com>
> Cc: Song Liu <songliubraving@fb.com>
> Cc: Yonghong Song <yhs@fb.com>
> Cc: Jens Axboe <axboe@kernel.dk>
> Cc: "David S. Miller" <davem@davemloft.net>
> Cc: linux-block@vger.kernel.org
> Cc: bpf@vger.kernel.org
> Cc: netdev@vger.kernel.org
> Signed-off-by: Tejun Heo <tj@kernel.org>
> [namhyung: fix build error in bpf_get_current_cgroup_id()]
> Signed-off-by: Namhyung Kim <namhyung@kernel.org>
> ---
>  fs/kernfs/dir.c                  | 36 ++++++++-----
>  fs/kernfs/file.c                 |  4 +-
>  fs/kernfs/inode.c                |  4 +-
>  fs/kernfs/kernfs-internal.h      |  2 -
>  fs/kernfs/mount.c                | 92 +++++++++++++++++++-------------
>  include/linux/cgroup.h           | 17 +++---
>  include/linux/exportfs.h         |  5 ++
>  include/linux/kernfs.h           | 47 +++++++++-------

>  include/trace/events/writeback.h | 92 ++++++++++++++++----------------

I only looked at the above file, and didn't see anything bad about it.

Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

-- Steve


>  kernel/bpf/helpers.c             |  2 +-
>  kernel/cgroup/cgroup.c           |  5 +-
>  kernel/trace/blktrace.c          | 66 +++++++++++------------
>  net/core/filter.c                |  4 +-
>  13 files changed, 207 insertions(+), 169 deletions(-)

[PATCH v2 2/2] cgroup: Use 64bit id from kernfs

[Namhyung Kim]

From: Tejun Heo <tj@kernel.org>

Use 64 bit id allocated by kernfs instead of using its own idr since
it seems not used for saving any information no more.  So let's get
rid of the cgroup_idr from cgroup_root.

The index of netprio_map is also changed to u64.

Cc: "David S. Miller" <davem@davemloft.net>
Cc: Neil Horman <nhorman@tuxdriver.com>
Cc: netdev@vger.kernel.org
Signed-off-by: Tejun Heo <tj@kernel.org>
[namhyung: split cgroup changes and fix netprio_map access]
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
---
 include/linux/cgroup-defs.h  | 18 +++--------
 include/net/netprio_cgroup.h |  8 ++---
 kernel/cgroup/cgroup.c       | 63 +++++++++++-------------------------
 net/core/netprio_cgroup.c    |  4 +--
 4 files changed, 29 insertions(+), 64 deletions(-)

diff --git a/include/linux/cgroup-defs.h b/include/linux/cgroup-defs.h
index 430e219e3aba..3811b3405ddc 100644
--- a/include/linux/cgroup-defs.h
+++ b/include/linux/cgroup-defs.h
@@ -354,15 +354,8 @@ struct cgroup {
 
 	unsigned long flags;		/* "unsigned long" so bitops work */
 
-	/*
-	 * idr allocated in-hierarchy ID.
-	 *
-	 * ID 0 is not used, the ID of the root cgroup is always 1, and a
-	 * new cgroup will be assigned with a smallest available ID.
-	 *
-	 * Allocating/Removing ID must be protected by cgroup_mutex.
-	 */
-	int id;
+	/* in-hierarchy ID allocated from kernfs */
+	u64 id;
 
 	/*
 	 * The depth this cgroup is at.  The root is at depth zero and each
@@ -488,7 +481,7 @@ struct cgroup {
 	struct cgroup_freezer_state freezer;
 
 	/* ids of the ancestors at each level including self */
-	int ancestor_ids[];
+	u64 ancestor_ids[];
 };
 
 /*
@@ -509,7 +502,7 @@ struct cgroup_root {
 	struct cgroup cgrp;
 
 	/* for cgrp->ancestor_ids[0] */
-	int cgrp_ancestor_id_storage;
+	u64 cgrp_ancestor_id_storage;
 
 	/* Number of cgroups in the hierarchy, used only for /proc/cgroups */
 	atomic_t nr_cgrps;
@@ -520,9 +513,6 @@ struct cgroup_root {
 	/* Hierarchy-specific flags */
 	unsigned int flags;
 
-	/* IDs for cgroups in this hierarchy */
-	struct idr cgroup_idr;
-
 	/* The path to use for release notifications. */
 	char release_agent_path[PATH_MAX];
 
diff --git a/include/net/netprio_cgroup.h b/include/net/netprio_cgroup.h
index cfc9441ef074..cd7c17cf73c7 100644
--- a/include/net/netprio_cgroup.h
+++ b/include/net/netprio_cgroup.h
@@ -15,14 +15,14 @@
 #if IS_ENABLED(CONFIG_CGROUP_NET_PRIO)
 struct netprio_map {
 	struct rcu_head rcu;
-	u32 priomap_len;
+	u64 priomap_len;
 	u32 priomap[];
 };
 
-static inline u32 task_netprioidx(struct task_struct *p)
+static inline u64 task_netprioidx(struct task_struct *p)
 {
 	struct cgroup_subsys_state *css;
-	u32 idx;
+	u64 idx;
 
 	rcu_read_lock();
 	css = task_css(p, net_prio_cgrp_id);
@@ -41,7 +41,7 @@ static inline void sock_update_netprioidx(struct sock_cgroup_data *skcd)
 
 #else /* !CONFIG_CGROUP_NET_PRIO */
 
-static inline u32 task_netprioidx(struct task_struct *p)
+static inline u64 task_netprioidx(struct task_struct *p)
 {
 	return 0;
 }
diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c
index b5dcbee5aa6c..4dc0f86bb4c5 100644
--- a/kernel/cgroup/cgroup.c
+++ b/kernel/cgroup/cgroup.c
@@ -1308,10 +1308,7 @@ static void cgroup_exit_root_id(struct cgroup_root *root)
 
 void cgroup_free_root(struct cgroup_root *root)
 {
-	if (root) {
-		idr_destroy(&root->cgroup_idr);
-		kfree(root);
-	}
+	kfree(root);
 }
 
 static void cgroup_destroy_root(struct cgroup_root *root)
@@ -1917,7 +1914,6 @@ void init_cgroup_root(struct cgroup_fs_context *ctx)
 	atomic_set(&root->nr_cgrps, 1);
 	cgrp->root = root;
 	init_cgroup_housekeeping(cgrp);
-	idr_init(&root->cgroup_idr);
 
 	root->flags = ctx->flags;
 	if (ctx->release_agent)
@@ -1938,12 +1934,6 @@ int cgroup_setup_root(struct cgroup_root *root, u16 ss_mask)
 
 	lockdep_assert_held(&cgroup_mutex);
 
-	ret = cgroup_idr_alloc(&root->cgroup_idr, root_cgrp, 1, 2, GFP_KERNEL);
-	if (ret < 0)
-		goto out;
-	root_cgrp->id = ret;
-	root_cgrp->ancestor_ids[0] = ret;
-
 	ret = percpu_ref_init(&root_cgrp->self.refcnt, css_release,
 			      0, GFP_KERNEL);
 	if (ret)
@@ -1976,6 +1966,8 @@ int cgroup_setup_root(struct cgroup_root *root, u16 ss_mask)
 		goto exit_root_id;
 	}
 	root_cgrp->kn = root->kf_root->kn;
+	root_cgrp->id = root_cgrp->kn->id;
+	root_cgrp->ancestor_ids[0] = root_cgrp->id;
 
 	ret = css_populate_dir(&root_cgrp->self);
 	if (ret)
@@ -4987,9 +4979,6 @@ static void css_release_work_fn(struct work_struct *work)
 			tcgrp->nr_dying_descendants--;
 		spin_unlock_irq(&css_set_lock);
 
-		cgroup_idr_remove(&cgrp->root->cgroup_idr, cgrp->id);
-		cgrp->id = -1;
-
 		/*
 		 * There are two control paths which try to determine
 		 * cgroup from dentry without going through kernfs -
@@ -5154,10 +5143,12 @@ static struct cgroup_subsys_state *css_create(struct cgroup *cgrp,
  * it isn't associated with its kernfs_node and doesn't have the control
  * mask applied.
  */
-static struct cgroup *cgroup_create(struct cgroup *parent)
+static struct cgroup *cgroup_create(struct cgroup *parent, const char *name,
+				    umode_t mode)
 {
 	struct cgroup_root *root = parent->root;
 	struct cgroup *cgrp, *tcgrp;
+	struct kernfs_node *kn;
 	int level = parent->level + 1;
 	int ret;
 
@@ -5177,15 +5168,14 @@ static struct cgroup *cgroup_create(struct cgroup *parent)
 			goto out_cancel_ref;
 	}
 
-	/*
-	 * Temporarily set the pointer to NULL, so idr_find() won't return
-	 * a half-baked cgroup.
-	 */
-	cgrp->id = cgroup_idr_alloc(&root->cgroup_idr, NULL, 2, 0, GFP_KERNEL);
-	if (cgrp->id < 0) {
-		ret = -ENOMEM;
+	/* create the directory */
+	kn = kernfs_create_dir(parent->kn, name, mode, cgrp);
+	if (IS_ERR(kn)) {
+		ret = PTR_ERR(kn);
 		goto out_stat_exit;
 	}
+	cgrp->kn = kn;
+	cgrp->id = kn->id;
 
 	init_cgroup_housekeeping(cgrp);
 
@@ -5195,7 +5185,7 @@ static struct cgroup *cgroup_create(struct cgroup *parent)
 
 	ret = psi_cgroup_alloc(cgrp);
 	if (ret)
-		goto out_idr_free;
+		goto out_kernfs_remove;
 
 	ret = cgroup_bpf_inherit(cgrp);
 	if (ret)
@@ -5248,12 +5238,6 @@ static struct cgroup *cgroup_create(struct cgroup *parent)
 	atomic_inc(&root->nr_cgrps);
 	cgroup_get_live(parent);
 
-	/*
-	 * @cgrp is now fully operational.  If something fails after this
-	 * point, it'll be released via the normal destruction path.
-	 */
-	cgroup_idr_replace(&root->cgroup_idr, cgrp, cgrp->id);
-
 	/*
 	 * On the default hierarchy, a child doesn't automatically inherit
 	 * subtree_control from the parent.  Each is configured manually.
@@ -5267,8 +5251,8 @@ static struct cgroup *cgroup_create(struct cgroup *parent)
 
 out_psi_free:
 	psi_cgroup_free(cgrp);
-out_idr_free:
-	cgroup_idr_remove(&root->cgroup_idr, cgrp->id);
+out_kernfs_remove:
+	kernfs_remove(cgrp->kn);
 out_stat_exit:
 	if (cgroup_on_dfl(parent))
 		cgroup_rstat_exit(cgrp);
@@ -5305,7 +5289,6 @@ static bool cgroup_check_hierarchy_limits(struct cgroup *parent)
 int cgroup_mkdir(struct kernfs_node *parent_kn, const char *name, umode_t mode)
 {
 	struct cgroup *parent, *cgrp;
-	struct kernfs_node *kn;
 	int ret;
 
 	/* do not accept '\n' to prevent making /proc/<pid>/cgroup unparsable */
@@ -5321,27 +5304,19 @@ int cgroup_mkdir(struct kernfs_node *parent_kn, const char *name, umode_t mode)
 		goto out_unlock;
 	}
 
-	cgrp = cgroup_create(parent);
+	cgrp = cgroup_create(parent, name, mode);
 	if (IS_ERR(cgrp)) {
 		ret = PTR_ERR(cgrp);
 		goto out_unlock;
 	}
 
-	/* create the directory */
-	kn = kernfs_create_dir(parent->kn, name, mode, cgrp);
-	if (IS_ERR(kn)) {
-		ret = PTR_ERR(kn);
-		goto out_destroy;
-	}
-	cgrp->kn = kn;
-
 	/*
 	 * This extra ref will be put in cgroup_free_fn() and guarantees
 	 * that @cgrp->kn is always accessible.
 	 */
-	kernfs_get(kn);
+	kernfs_get(cgrp->kn);
 
-	ret = cgroup_kn_set_ugid(kn);
+	ret = cgroup_kn_set_ugid(cgrp->kn);
 	if (ret)
 		goto out_destroy;
 
@@ -5356,7 +5331,7 @@ int cgroup_mkdir(struct kernfs_node *parent_kn, const char *name, umode_t mode)
 	TRACE_CGROUP_PATH(mkdir, cgrp);
 
 	/* let's create and online css's */
-	kernfs_activate(kn);
+	kernfs_activate(cgrp->kn);
 
 	ret = 0;
 	goto out_unlock;
diff --git a/net/core/netprio_cgroup.c b/net/core/netprio_cgroup.c
index 256b7954b720..326d2d6b86e0 100644
--- a/net/core/netprio_cgroup.c
+++ b/net/core/netprio_cgroup.c
@@ -93,7 +93,7 @@ static int extend_netdev_table(struct net_device *dev, u32 target_idx)
 static u32 netprio_prio(struct cgroup_subsys_state *css, struct net_device *dev)
 {
 	struct netprio_map *map = rcu_dereference_rtnl(dev->priomap);
-	int id = css->cgroup->id;
+	u64 id = css->cgroup->id;
 
 	if (map && id < map->priomap_len)
 		return map->priomap[id];
@@ -113,7 +113,7 @@ static int netprio_set_prio(struct cgroup_subsys_state *css,
 			    struct net_device *dev, u32 prio)
 {
 	struct netprio_map *map;
-	int id = css->cgroup->id;
+	u64 id = css->cgroup->id;
 	int ret;
 
 	/* avoid extending priomap for zero writes */
-- 
2.24.0.rc1.363.gb1bccd3e3d-goog

Re: [PATCH v2 2/2] cgroup: Use 64bit id from kernfs

[David Miller]

From: Namhyung Kim <namhyung@kernel.org>
Date: Mon,  4 Nov 2019 17:45:20 +0900

> From: Tejun Heo <tj@kernel.org>
> 
> Use 64 bit id allocated by kernfs instead of using its own idr since
> it seems not used for saving any information no more.  So let's get
> rid of the cgroup_idr from cgroup_root.
> 
> The index of netprio_map is also changed to u64.
> 
> Cc: "David S. Miller" <davem@davemloft.net>
> Cc: Neil Horman <nhorman@tuxdriver.com>
> Cc: netdev@vger.kernel.org
> Signed-off-by: Tejun Heo <tj@kernel.org>
> [namhyung: split cgroup changes and fix netprio_map access]
> Signed-off-by: Namhyung Kim <namhyung@kernel.org>

Acked-by: David S. Miller <davem@davemloft.net>