tracing: Automatically mount tracefs on debugfs/tracing (f76180bc) · Commits · 戴 / test

kernel/trace/trace.c

+33 −3

Original line number	Diff line number	Diff line
		@@ -32,6 +32,7 @@
		#include <linux/splice.h>
		#include <linux/kdebug.h>
		#include <linux/string.h>
		#include <linux/mount.h>
		#include <linux/rwsem.h>
		#include <linux/slab.h>
		#include <linux/ctype.h>
		@@ -6535,6 +6536,28 @@ init_tracer_tracefs(struct trace_array tr, struct dentry d_tracer)

		}

		static struct vfsmount trace_automount(void ingore)
		{
		struct vfsmount *mnt;
		struct file_system_type *type;

		/*
		* To maintain backward compatibility for tools that mount
		* debugfs to get to the tracing facility, tracefs is automatically
		* mounted to the debugfs/tracing directory.
		*/
		type = get_fs_type("tracefs");
		if (!type)
		return NULL;
		mnt = vfs_kern_mount(type, 0, "tracefs", NULL);
		put_filesystem(type);
		if (IS_ERR(mnt))
		return NULL;
		mntget(mnt);

		return mnt;
		}

		/**
		* tracing_init_dentry - initialize top level trace array
		*
		@@ -6546,14 +6569,21 @@ struct dentry *tracing_init_dentry(void)
		{
		struct trace_array *tr = &global_trace;

		/* The top level trace array uses NULL as parent */
		if (tr->dir)
		return tr->dir;
		return NULL;

		if (WARN_ON(!debugfs_initialized()))
		return ERR_PTR(-ENODEV);

		tr->dir = debugfs_create_dir("tracing", NULL);

		/*
		* As there may still be users that expect the tracing
		* files to exist in debugfs/tracing, we must automount
		* the tracefs file system there, so older tools still
		* work with the newer kerenl.
		*/
		tr->dir = debugfs_create_automount("tracing", NULL,
		trace_automount, NULL);
		if (!tr->dir) {
		pr_warn_once("Could not create debugfs directory 'tracing'\n");
		return ERR_PTR(-ENOMEM);

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