kernfs: convert kernfs_node->id from union kernfs_node_id to u64

kernfs_node->id is currently a union kernfs_node_id which represents
either a 32bit (ino, gen) pair or u64 value.  I can't see much value
in the usage of the union - all that's needed is a 64bit ID which the
current code is already limited to.  Using a union makes the code
unnecessarily complicated and prevents using 64bit ino without adding
practical benefits.

This patch drops union kernfs_node_id and makes kernfs_node->id a u64.
ino is stored in the lower 32bits and gen upper.  Accessors -
kernfs[_id]_ino() and kernfs[_id]_gen() - are added to retrieve the
ino and gen.  This simplifies ID handling less cumbersome and will
allow using 64bit inos on supported archs.

This patch doesn't make any functional changes.

Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Alexei Starovoitov <ast@kernel.org>

4 files changed, 12 insertions, 13 deletions

diff --git a/fs/kernfs/dir.c b/fs/kernfs/dir.c
index beabb585a7d8..c67afb591e5b 100644
--- a/fs/kernfs/dir.c
+++ b/fs/kernfs/dir.c
@@ -532,7 +532,7 @@ 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, kernfs_ino(kn));
 	spin_unlock(&kernfs_idr_lock);
 	kmem_cache_free(kernfs_node_cache, kn);
 
@@ -639,8 +639,8 @@ 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;
 
 	atomic_set(&kn->count, 1);
 	atomic_set(&kn->active, KN_DEACTIVATED_BIAS);
@@ -671,7 +671,7 @@ 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, kernfs_ino(kn));
  err_out2:
 	kmem_cache_free(kernfs_node_cache, kn);
  err_out1:
@@ -1656,7 +1656,7 @@ 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 @@ repeat:
 		 * 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 @@ repeat:
 		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/mount.c b/fs/kernfs/mount.c
index 067b7c380056..f05d5d6f926d 100644
--- a/fs/kernfs/mount.c
+++ b/fs/kernfs/mount.c
@@ -57,15 +57,14 @@ const struct super_operations kernfs_sops = {
  * 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)
+struct kernfs_node *kernfs_get_node_by_id(struct kernfs_root *root, u64 id)
 {
 	struct kernfs_node *kn;
 
-	kn = kernfs_find_and_get_node_by_ino(root, id->ino);
+	kn = kernfs_find_and_get_node_by_ino(root, kernfs_id_ino(id));
 	if (!kn)
 		return NULL;
-	if (kn->id.generation != id->generation) {
+	if (kernfs_gen(kn) != kernfs_id_gen(id)) {
 		kernfs_put(kn);
 		return NULL;
 	}