sysfs: implement sysfs_get_dentry()

Some sysfs operations require dentry and inode.  sysfs_get_dentry()
looks up and gets dentry for the specified sysfs_dirent.  It finds the
first ancestor with dentry attached and starts looking up dentries
from there.

Looking up from the nearest ancestor is necessary to support shadowed
directories because we can't reliably lookup dentry for one of the
shadows.  Dentries for each shadow will be pinned in memory such that
they can serve as the starting point for dentry lookup.

Signed-off-by: Tejun Heo <htejun@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 1 insertions, 0 deletions

diff --git a/fs/sysfs/sysfs.h b/fs/sysfs/sysfs.h
index 92fe1e51a29b..72530dc666fd 100644
--- a/fs/sysfs/sysfs.h
+++ b/fs/sysfs/sysfs.h
@@ -54,6 +54,7 @@ struct sysfs_addrm_cxt {
 extern struct vfsmount * sysfs_mount;
 extern struct kmem_cache *sysfs_dir_cachep;
 
+extern struct dentry *sysfs_get_dentry(struct sysfs_dirent *sd);
 extern void sysfs_link_sibling(struct sysfs_dirent *sd);
 extern void sysfs_unlink_sibling(struct sysfs_dirent *sd);
 extern struct sysfs_dirent *sysfs_get_active(struct sysfs_dirent *sd);