linux-kernel - [PATCH 4/4] sysfs: Kill nlink counting.

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Date:	Sun, 18 Dec 2011 20:09:31 -0800
From:	ebiederm@...ssion.com (Eric W. Biederman)
To:	Greg Kroah-Hartman <gregkh@...e.de>
Cc:	<linux-kernel@...r.kernel.org>, Tejun Heo <tj@...nel.org>,
	Mikulas Patocka <mpatocka@...hat.com>
Subject: [PATCH 4/4] sysfs: Kill nlink counting.


Tracking the number of subdirectories requires an extra field that increases
the size of sysfs_dirent.  nlinks are not particularly interesting for sysfs
and the nlink counts are wrong when network namespaces are involved so stop
counting them, and always return nlink == 1.  Userspace already knows that
directories with nlink == 1 have an nlink count they can't use to count
subdirectories.

This reduces the size of sysfs_dirent by 8 bytes on 64bit platforms.

Signed-off-by: Eric W. Biederman <ebiederm@...ssion.com>
---
 fs/sysfs/dir.c   |    6 ------
 fs/sysfs/inode.c |    3 ---
 fs/sysfs/sysfs.h |    1 -
 3 files changed, 0 insertions(+), 10 deletions(-)

diff --git a/fs/sysfs/dir.c b/fs/sysfs/dir.c
index 0589c9a..ea64d01 100644
--- a/fs/sysfs/dir.c
+++ b/fs/sysfs/dir.c
@@ -91,9 +91,6 @@ static int sysfs_link_sibling(struct sysfs_dirent *sd)
 	struct rb_node **node = &sd->s_parent->s_dir.children.rb_node;
 	struct rb_node *parent = NULL;
 
-	if (sysfs_type(sd) == SYSFS_DIR)
-		sd->s_parent->s_dir.subdirs++;
-
 	while (*node) {
 		struct sysfs_dirent *pos;
 		int result;
@@ -126,9 +123,6 @@ static int sysfs_link_sibling(struct sysfs_dirent *sd)
  */
 static void sysfs_unlink_sibling(struct sysfs_dirent *sd)
 {
-	if (sysfs_type(sd) == SYSFS_DIR)
-		sd->s_parent->s_dir.subdirs--;
-
 	rb_erase(&sd->s_rb, &sd->s_parent->s_dir.children);
 }
 
diff --git a/fs/sysfs/inode.c b/fs/sysfs/inode.c
index c81b22f..c7be716 100644
--- a/fs/sysfs/inode.c
+++ b/fs/sysfs/inode.c
@@ -216,9 +216,6 @@ static void sysfs_refresh_inode(struct sysfs_dirent *sd, struct inode *inode)
 					    iattrs->ia_secdata,
 					    iattrs->ia_secdata_len);
 	}
-
-	if (sysfs_type(sd) == SYSFS_DIR)
-		set_nlink(inode, sd->s_dir.subdirs + 2);
 }
 
 int sysfs_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat)
diff --git a/fs/sysfs/sysfs.h b/fs/sysfs/sysfs.h
index 3f23061..2adb052 100644
--- a/fs/sysfs/sysfs.h
+++ b/fs/sysfs/sysfs.h
@@ -19,7 +19,6 @@ struct sysfs_open_dirent;
 struct sysfs_elem_dir {
 	struct kobject		*kobj;
 
-	unsigned long		subdirs;
 	/* children rbtree starts here and goes through sd->s_rb */
 	struct rb_root		children;
 };
-- 
1.7.2.5

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