kernfs: make kernfs_walk_ns() use kernfs_pr_cont_buf[] (e56ed358) · Commits · 戴 / test

kernfs_walk_ns() uses a static path_buf[PATH_MAX] to separate out path components. Keeping around the 4k buffer just for kernfs_walk_ns() is wasteful. This patch makes it piggyback on kernfs_pr_cont_buf[] instead. This requires kernfs_walk_ns() to hold kernfs_rename_lock. Signed-off-by:

Tejun Heo <tj@kernel.org> Reported-by:

Geert Uytterhoeven <geert@linux-m68k.org> Signed-off-by:

Greg Kroah-Hartman <gregkh@linuxfoundation.org>

fs/kernfs/dir.c

+14 −5

Original line number	Diff line number	Diff line
		@@ -691,15 +691,22 @@ static struct kernfs_node kernfs_walk_ns(struct kernfs_node parent,
		const unsigned char *path,
		const void *ns)
		{
		static char path_buf[PATH_MAX]; /* protected by kernfs_mutex */
		size_t len = strlcpy(path_buf, path, PATH_MAX);
		char *p = path_buf;
		char *name;
		size_t len;
		char p, name;

		lockdep_assert_held(&kernfs_mutex);

		if (len >= PATH_MAX)
		/* grab kernfs_rename_lock to piggy back on kernfs_pr_cont_buf */
		spin_lock_irq(&kernfs_rename_lock);

		len = strlcpy(kernfs_pr_cont_buf, path, sizeof(kernfs_pr_cont_buf));

		if (len >= sizeof(kernfs_pr_cont_buf)) {
		spin_unlock_irq(&kernfs_rename_lock);
		return NULL;
		}

		p = kernfs_pr_cont_buf;

		while ((name = strsep(&p, "/")) && parent) {
		if (*name == '\0')
		@@ -707,6 +714,8 @@ static struct kernfs_node kernfs_walk_ns(struct kernfs_node parent,
		parent = kernfs_find_ns(parent, name, ns);
		}

		spin_unlock_irq(&kernfs_rename_lock);

		return parent;
		}

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