namei: handle absolute symlinks without dropping out of RCU mode (8f47a016) · Commits · e / devices / android_kernel_fairphone_FP3

fs/namei.c

+20 −11

Original line number	Diff line number	Diff line
		@@ -499,7 +499,7 @@ struct nameidata {
		struct path root;
		struct inode inode; / path.dentry.d_inode */
		unsigned int flags;
		unsigned seq, m_seq;
		unsigned seq, m_seq, root_seq;
		int last_type;
		unsigned depth;
		int total_link_count;
		@@ -788,14 +788,14 @@ static __always_inline void set_root(struct nameidata *nd)
		static __always_inline unsigned set_root_rcu(struct nameidata *nd)
		{
		struct fs_struct *fs = current->fs;
		unsigned seq, res;
		unsigned seq;

		do {
		seq = read_seqcount_begin(&fs->seq);
		nd->root = fs->root;
		res = __read_seqcount_begin(&nd->root.dentry->d_seq);
		nd->root_seq = __read_seqcount_begin(&nd->root.dentry->d_seq);
		} while (read_seqcount_retry(&fs->seq, seq));
		return res;
		return nd->root_seq;
		}

		static void path_put_conditional(struct path path, struct nameidata nd)
		@@ -995,15 +995,23 @@ const char get_link(struct nameidata nd)
		}
		if (*res == '/') {
		if (nd->flags & LOOKUP_RCU) {
		if (unlikely(unlazy_walk(nd, NULL, 0)))
		struct dentry *d;
		if (!nd->root.mnt)
		set_root_rcu(nd);
		nd->path = nd->root;
		d = nd->path.dentry;
		nd->inode = d->d_inode;
		nd->seq = nd->root_seq;
		if (unlikely(read_seqcount_retry(&d->d_seq, nd->seq)))
		return ERR_PTR(-ECHILD);
		}
		} else {
		if (!nd->root.mnt)
		set_root(nd);
		path_put(&nd->path);
		nd->path = nd->root;
		path_get(&nd->root);
		nd->inode = nd->path.dentry->d_inode;
		}
		nd->flags \|= LOOKUP_JUMPED;
		while (unlikely(*++res == '/'))
		;
		@@ -1979,6 +1987,7 @@ static const char path_init(int dfd, const struct filename name,
		if (flags & LOOKUP_RCU) {
		rcu_read_lock();
		nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq);
		nd->root_seq = nd->seq;
		nd->m_seq = read_seqbegin(&mount_lock);
		} else {
		path_get(&nd->path);