* Drop dentry for @sd. @sd must have been unlinked from its
* parent on entry to this function such that it can't be looked
* up anymore.
- *
- * @sd->s_dentry which is protected with sysfs_assoc_lock points
- * to the currently associated dentry but we're not holding a
- * reference to it and racing with dput(). Grab dcache_lock and
- * verify dentry before dropping it. If @sd->s_dentry is NULL or
- * dput() beats us, no need to bother.
*/
static void sysfs_drop_dentry(struct sysfs_dirent *sd)
{
- struct dentry *dentry = NULL;
struct inode *inode;
+ struct dentry *dentry;
+
+ inode = ilookup(sysfs_sb, sd->s_ino);
+ if (!inode)
+ return;
- /* We're not holding a reference to ->s_dentry dentry but the
- * field will stay valid as long as sysfs_assoc_lock is held.
+ /* Drop any existing dentries associated with sd.
+ *
+ * For the dentry to be properly freed we need to grab a
+ * reference to the dentry under the dcache lock, unhash it,
+ * and then put it. The playing with the dentry count allows
+ * dput to immediately free the dentry if it is not in use.
*/
- spin_lock(&sysfs_assoc_lock);
+repeat:
spin_lock(&dcache_lock);
-
- /* drop dentry if it's there and dput() didn't kill it yet */
- if (sd->s_dentry && sd->s_dentry->d_inode) {
- dentry = dget_locked(sd->s_dentry);
+ list_for_each_entry(dentry, &inode->i_dentry, d_alias) {
+ if (d_unhashed(dentry))
+ continue;
+ dget_locked(dentry);
spin_lock(&dentry->d_lock);
__d_drop(dentry);
spin_unlock(&dentry->d_lock);
+ spin_unlock(&dcache_lock);
+ dput(dentry);
+ goto repeat;
}
-
spin_unlock(&dcache_lock);
- spin_unlock(&sysfs_assoc_lock);
-
- dput(dentry);
/* adjust nlink and update timestamp */
- inode = ilookup(sysfs_sb, sd->s_ino);
- if (inode) {
- mutex_lock(&inode->i_mutex);
+ mutex_lock(&inode->i_mutex);
- inode->i_ctime = CURRENT_TIME;
+ inode->i_ctime = CURRENT_TIME;
+ drop_nlink(inode);
+ if (sysfs_type(sd) == SYSFS_DIR)
drop_nlink(inode);
- if (sysfs_type(sd) == SYSFS_DIR)
- drop_nlink(inode);
- mutex_unlock(&inode->i_mutex);
- iput(inode);
- }
+ mutex_unlock(&inode->i_mutex);
+
+ iput(inode);
}
/**