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Commit f657a666 authored by Al Viro's avatar Al Viro
Browse files

get rid of trylock loop around dentry_kill() 



In case when trylock in there fails, deal with it directly in
dentry_kill().  Note that in cases when we drop and retake
->d_lock, we need to recheck whether to retain the dentry.
Another thing is that dropping/retaking ->d_lock might have
ended up with negative dentry turning into positive; that,
of course, can happen only once...

Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent 62d9956c

fs/dcache.c

+27 −7
Original line number Diff line number Diff line
@@ -651,23 +651,43 @@ static struct dentry *dentry_kill(struct dentry *dentry) 
	struct dentry *parent = NULL;



	if (inode && unlikely(!spin_trylock(&inode->i_lock)))

		goto failed;

		goto slow_positive;



	if (!IS_ROOT(dentry)) {

		parent = dentry->d_parent;

		if (unlikely(!spin_trylock(&parent->d_lock))) {

			if (inode)

				spin_unlock(&inode->i_lock);

			goto failed;

			parent = __lock_parent(dentry);

			if (likely(inode || !dentry->d_inode))

				goto got_locks;

			/* negative that became positive */

			if (parent)

				spin_unlock(&parent->d_lock);

			inode = dentry->d_inode;

			goto slow_positive;

		}

	}



	__dentry_kill(dentry);

	return parent;



failed:

slow_positive:

	spin_unlock(&dentry->d_lock);

	return dentry; /* try again with same dentry */

	spin_lock(&inode->i_lock);

	spin_lock(&dentry->d_lock);

	parent = lock_parent(dentry);

got_locks:

	if (unlikely(dentry->d_lockref.count != 1)) {

		dentry->d_lockref.count--;

	} else if (likely(!retain_dentry(dentry))) {

		__dentry_kill(dentry);

		return parent;

	}

	/* we are keeping it, after all */

	if (inode)

		spin_unlock(&inode->i_lock);

	if (parent)

		spin_unlock(&parent->d_lock);

	spin_unlock(&dentry->d_lock);

	return NULL;

}



/*