sysfs: reimplement sysfs_drop_dentry()

This patch reimplements sysfs_drop_dentry() such that remove_dir() can
use it to drop dentry instead of using a separate mechanism.  With
this change, making directories reclaimable is much easier.

This patch used to contain fixes for two race conditions around
sd->s_dentry but that part has been separated out and included into
mainline early as commit 6aa054aadfea613a437ad0b15d38eca2b963fc0a and
dd14cbc994709a1c5a64ed3621f583c49a27e521.

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

1 files changed, 5 insertions, 13 deletions

diff --git a/fs/sysfs/dir.c b/fs/sysfs/dir.c
index 01eeb4b954b1..bc11a263aa53 100644
--- a/fs/sysfs/dir.c
+++ b/fs/sysfs/dir.c
@@ -372,22 +372,19 @@ const struct inode_operations sysfs_dir_inode_operations = {
 
 static void remove_dir(struct dentry * d)
 {
-        struct dentry * parent = dget(d->d_parent);
-        struct sysfs_dirent * sd;
+        struct dentry *parent = d->d_parent;
+        struct sysfs_dirent *sd = d->d_fsdata;
 
         mutex_lock(&parent->d_inode->i_mutex);
-        d_delete(d);
-        sd = d->d_fsdata;
+
         list_del_init(&sd->s_sibling);
-        if (d->d_inode)
-                simple_rmdir(parent->d_inode,d);
 
         pr_debug(" o %s removing done (%d)\n",d->d_name.name,
                  atomic_read(&d->d_count));
 
         mutex_unlock(&parent->d_inode->i_mutex);
-        dput(parent);
 
+        sysfs_drop_dentry(sd);
         sysfs_deactivate(sd);
         sysfs_put(sd);
 }
@@ -404,7 +401,6 @@ static void __sysfs_remove_dir(struct dentry *dentry)
         struct sysfs_dirent * parent_sd;
         struct sysfs_dirent * sd, * tmp;
 
-        dget(dentry);
         if (!dentry)
                 return;
 
@@ -415,21 +411,17 @@ static void __sysfs_remove_dir(struct dentry *dentry)
                 if (!sd->s_type || !(sd->s_type & SYSFS_NOT_PINNED))
                         continue;
                 list_move(&sd->s_sibling, &removed);
-                sysfs_drop_dentry(sd, dentry);
         }
         mutex_unlock(&dentry->d_inode->i_mutex);
 
         list_for_each_entry_safe(sd, tmp, &removed, s_sibling) {
                 list_del_init(&sd->s_sibling);
+                sysfs_drop_dentry(sd);
                 sysfs_deactivate(sd);
                 sysfs_put(sd);
         }
 
         remove_dir(dentry);
-        /**
-         * Drop reference from dget() on entrance.
-         */
-        dput(dentry);
 }
 
 /**