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Commit 7f9838fd authored by Mikulas Patocka's avatar Mikulas Patocka Committed by Greg Kroah-Hartman
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sysfs: count subdirectories 



sysfs: count subdirectories

This patch introduces a subdirectory counter for each sysfs directory.

Without the patch, sysfs_refresh_inode would walk all entries of the directory
to calculate the number of subdirectories.

This patch improves time of "ls -la /sys/block" when there are 10000 block
devices from 9 seconds to 0.19 seconds.

Signed-off-by: default avatarMikulas Patocka <mpatocka@redhat.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@suse.de>
parent 86028619

fs/sysfs/dir.c

+6 −0
Original line number Diff line number Diff line
@@ -47,6 +47,9 @@ static void sysfs_link_sibling(struct sysfs_dirent *sd) 


	BUG_ON(sd->s_sibling);



	if (sysfs_type(sd) == SYSFS_DIR)

		parent_sd->s_dir.subdirs++;



	/* Store directory entries in order by ino.  This allows

	 * readdir to properly restart without having to add a

	 * cursor into the s_dir.children list.
@@ -73,6 +76,9 @@ static void sysfs_unlink_sibling(struct sysfs_dirent *sd) 
{

	struct sysfs_dirent **pos;



	if (sysfs_type(sd) == SYSFS_DIR)

		sd->s_parent->s_dir.subdirs--;



	for (pos = &sd->s_parent->s_dir.children; *pos;

	     pos = &(*pos)->s_sibling) {

		if (*pos == sd) {

fs/sysfs/inode.c

+1 −13
Original line number Diff line number Diff line
@@ -202,18 +202,6 @@ static inline void set_inode_attr(struct inode * inode, struct iattr * iattr) 
	inode->i_ctime = iattr->ia_ctime;

}



static int sysfs_count_nlink(struct sysfs_dirent *sd)

{

	struct sysfs_dirent *child;

	int nr = 0;



	for (child = sd->s_dir.children; child; child = child->s_sibling)

		if (sysfs_type(child) == SYSFS_DIR)

			nr++;



	return nr + 2;

}



static void sysfs_refresh_inode(struct sysfs_dirent *sd, struct inode *inode)

{

	struct sysfs_inode_attrs *iattrs = sd->s_iattr;
@@ -230,7 +218,7 @@ static void sysfs_refresh_inode(struct sysfs_dirent *sd, struct inode *inode) 
	}



	if (sysfs_type(sd) == SYSFS_DIR)

		inode->i_nlink = sysfs_count_nlink(sd);

		inode->i_nlink = sd->s_dir.subdirs + 2;

}



int sysfs_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat)

fs/sysfs/sysfs.h

+2 −0
Original line number Diff line number Diff line
@@ -19,6 +19,8 @@ struct sysfs_elem_dir { 
	struct kobject		*kobj;

	/* children list starts here and goes through sd->s_sibling */

	struct sysfs_dirent	*children;



	unsigned long		subdirs;

};



struct sysfs_elem_symlink {