[PATCH v3 09/10] eventfs: moving tracing/events to eventfs

From: Ajay Kaher
Date: Thu Jun 01 2023 - 05:02:36 EST

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Till now /sys/kernel/debug/tracing/events is a part of tracefs,
with-in this patch creating 'events' and it's sub-dir as eventfs.
Basically replacing tracefs calls with eventfs calls for 'events'.

Signed-off-by: Ajay Kaher <akaher@xxxxxxxxxx>
Co-developed-by: Steven Rostedt (VMware) <rostedt@xxxxxxxxxxx>
Signed-off-by: Steven Rostedt (VMware) <rostedt@xxxxxxxxxxx>
Tested-by: Ching-lin Yu <chinglinyu@xxxxxxxxxx>
---
fs/tracefs/inode.c | 18 ++++++++++
include/linux/trace_events.h | 1 +
kernel/trace/trace.h | 2 +-
kernel/trace/trace_events.c | 67 +++++++++++++++++++-----------------
4 files changed, 55 insertions(+), 33 deletions(-)

diff --git a/fs/tracefs/inode.c b/fs/tracefs/inode.c
index 76820d3e9..a098d7153 100644
--- a/fs/tracefs/inode.c
+++ b/fs/tracefs/inode.c
@@ -374,6 +374,23 @@ static const struct super_operations tracefs_super_operations = {
.show_options = tracefs_show_options,
};

+static void tracefs_dentry_iput(struct dentry *dentry, struct inode *inode)
+{
+ struct tracefs_inode *ti;
+
+ if (!dentry || !inode)
+ return;
+
+ ti = get_tracefs(inode);
+ if (ti && ti->flags & TRACEFS_EVENT_INODE)
+ eventfs_set_ef_status_free(dentry);
+ iput(inode);
+}
+
+static const struct dentry_operations tracefs_dentry_operations = {
+ .d_iput = tracefs_dentry_iput,
+};
+
static int trace_fill_super(struct super_block *sb, void *data, int silent)
{
static const struct tree_descr trace_files[] = {{""}};
@@ -396,6 +413,7 @@ static int trace_fill_super(struct super_block *sb, void *data, int silent)
goto fail;

sb->s_op = &tracefs_super_operations;
+ sb->s_d_op = &tracefs_dentry_operations;

tracefs_apply_options(sb, false);

diff --git a/include/linux/trace_events.h b/include/linux/trace_events.h
index 0e373222a..696843d46 100644
--- a/include/linux/trace_events.h
+++ b/include/linux/trace_events.h
@@ -635,6 +635,7 @@ struct trace_event_file {
struct list_head list;
struct trace_event_call *event_call;
struct event_filter __rcu *filter;
+ struct eventfs_file *ef;
struct dentry *dir;
struct trace_array *tr;
struct trace_subsystem_dir *system;
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index b895c3346..b265ae2df 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -1310,7 +1310,7 @@ struct trace_subsystem_dir {
struct list_head list;
struct event_subsystem *subsystem;
struct trace_array *tr;
- struct dentry *entry;
+ struct eventfs_file *ef;
int ref_count;
int nr_events;
};
diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index 16bc5ba45..94aa6f9c9 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -988,7 +988,8 @@ static void remove_subsystem(struct trace_subsystem_dir *dir)
return;

if (!--dir->nr_events) {
- tracefs_remove(dir->entry);
+ if (dir->ef)
+ eventfs_remove(dir->ef);
list_del(&dir->list);
__put_system_dir(dir);
}
@@ -1009,7 +1010,8 @@ static void remove_event_file_dir(struct trace_event_file *file)

tracefs_remove(dir);
}
-
+ if (file->ef)
+ eventfs_remove(file->ef);
list_del(&file->list);
remove_subsystem(file->system);
free_event_filter(file->filter);
@@ -2295,13 +2297,13 @@ create_new_subsystem(const char *name)
return NULL;
}

-static struct dentry *
+static struct eventfs_file *
event_subsystem_dir(struct trace_array *tr, const char *name,
struct trace_event_file *file, struct dentry *parent)
{
struct event_subsystem *system, *iter;
struct trace_subsystem_dir *dir;
- struct dentry *entry;
+ int res;

/* First see if we did not already create this dir */
list_for_each_entry(dir, &tr->systems, list) {
@@ -2309,7 +2311,7 @@ event_subsystem_dir(struct trace_array *tr, const char *name,
if (strcmp(system->name, name) == 0) {
dir->nr_events++;
file->system = dir;
- return dir->entry;
+ return dir->ef;
}
}

@@ -2333,8 +2335,8 @@ event_subsystem_dir(struct trace_array *tr, const char *name,
} else
__get_system(system);

- dir->entry = tracefs_create_dir(name, parent);
- if (!dir->entry) {
+ dir->ef = eventfs_add_subsystem_dir(name, parent, &tr->eventfs_rwsem);
+ if (IS_ERR(dir->ef)) {
pr_warn("Failed to create system directory %s\n", name);
__put_system(system);
goto out_free;
@@ -2349,22 +2351,22 @@ event_subsystem_dir(struct trace_array *tr, const char *name,
/* the ftrace system is special, do not create enable or filter files */
if (strcmp(name, "ftrace") != 0) {

- entry = tracefs_create_file("filter", TRACE_MODE_WRITE,
- dir->entry, dir,
+ res = eventfs_add_file("filter", TRACE_MODE_WRITE,
+ dir->ef, dir,
&ftrace_subsystem_filter_fops);
- if (!entry) {
+ if (res) {
kfree(system->filter);
system->filter = NULL;
pr_warn("Could not create tracefs '%s/filter' entry\n", name);
}

- trace_create_file("enable", TRACE_MODE_WRITE, dir->entry, dir,
+ eventfs_add_file("enable", TRACE_MODE_WRITE, dir->ef, dir,
&ftrace_system_enable_fops);
}

list_add(&dir->list, &tr->systems);

- return dir->entry;
+ return dir->ef;

out_free:
kfree(dir);
@@ -2418,7 +2420,7 @@ event_create_dir(struct dentry *parent, struct trace_event_file *file)
{
struct trace_event_call *call = file->event_call;
struct trace_array *tr = file->tr;
- struct dentry *d_events;
+ struct eventfs_file *ef_subsystem = NULL;
const char *name;
int ret;

@@ -2430,24 +2432,24 @@ event_create_dir(struct dentry *parent, struct trace_event_file *file)
if (WARN_ON_ONCE(strcmp(call->class->system, TRACE_SYSTEM) == 0))
return -ENODEV;

- d_events = event_subsystem_dir(tr, call->class->system, file, parent);
- if (!d_events)
+ ef_subsystem = event_subsystem_dir(tr, call->class->system, file, parent);
+ if (!ef_subsystem)
return -ENOMEM;

name = trace_event_name(call);
- file->dir = tracefs_create_dir(name, d_events);
- if (!file->dir) {
+ file->ef = eventfs_add_dir(name, ef_subsystem, &tr->eventfs_rwsem);
+ if (IS_ERR(file->ef)) {
pr_warn("Could not create tracefs '%s' directory\n", name);
return -1;
}

if (call->class->reg && !(call->flags & TRACE_EVENT_FL_IGNORE_ENABLE))
- trace_create_file("enable", TRACE_MODE_WRITE, file->dir, file,
+ eventfs_add_file("enable", TRACE_MODE_WRITE, file->ef, file,
&ftrace_enable_fops);

#ifdef CONFIG_PERF_EVENTS
if (call->event.type && call->class->reg)
- trace_create_file("id", TRACE_MODE_READ, file->dir,
+ eventfs_add_file("id", TRACE_MODE_READ, file->ef,
(void *)(long)call->event.type,
&ftrace_event_id_fops);
#endif
@@ -2463,27 +2465,27 @@ event_create_dir(struct dentry *parent, struct trace_event_file *file)
* triggers or filters.
*/
if (!(call->flags & TRACE_EVENT_FL_IGNORE_ENABLE)) {
- trace_create_file("filter", TRACE_MODE_WRITE, file->dir,
+ eventfs_add_file("filter", TRACE_MODE_WRITE, file->ef,
file, &ftrace_event_filter_fops);

- trace_create_file("trigger", TRACE_MODE_WRITE, file->dir,
+ eventfs_add_file("trigger", TRACE_MODE_WRITE, file->ef,
file, &event_trigger_fops);
}

#ifdef CONFIG_HIST_TRIGGERS
- trace_create_file("hist", TRACE_MODE_READ, file->dir, file,
+ eventfs_add_file("hist", TRACE_MODE_READ, file->ef, file,
&event_hist_fops);
#endif
#ifdef CONFIG_HIST_TRIGGERS_DEBUG
- trace_create_file("hist_debug", TRACE_MODE_READ, file->dir, file,
+ eventfs_add_file("hist_debug", TRACE_MODE_READ, file->ef, file,
&event_hist_debug_fops);
#endif
- trace_create_file("format", TRACE_MODE_READ, file->dir, call,
+ eventfs_add_file("format", TRACE_MODE_READ, file->ef, call,
&ftrace_event_format_fops);

#ifdef CONFIG_TRACE_EVENT_INJECT
if (call->event.type && call->class->reg)
- trace_create_file("inject", 0200, file->dir, file,
+ eventfs_add_file("inject", 0200, file->ef, file,
&event_inject_fops);
#endif

@@ -3636,21 +3638,22 @@ create_event_toplevel_files(struct dentry *parent, struct trace_array *tr)
{
struct dentry *d_events;
struct dentry *entry;
+ int error = 0;

entry = trace_create_file("set_event", TRACE_MODE_WRITE, parent,
tr, &ftrace_set_event_fops);
if (!entry)
return -ENOMEM;

- d_events = tracefs_create_dir("events", parent);
- if (!d_events) {
+ d_events = eventfs_create_events_dir("events", parent, &tr->eventfs_rwsem);
+ if (IS_ERR(d_events)) {
pr_warn("Could not create tracefs 'events' directory\n");
return -ENOMEM;
}

- entry = trace_create_file("enable", TRACE_MODE_WRITE, d_events,
+ error = eventfs_add_top_file("enable", TRACE_MODE_WRITE, d_events,
tr, &ftrace_tr_enable_fops);
- if (!entry)
+ if (error)
return -ENOMEM;

/* There are not as crucial, just warn if they are not created */
@@ -3663,11 +3666,11 @@ create_event_toplevel_files(struct dentry *parent, struct trace_array *tr)
&ftrace_set_event_notrace_pid_fops);

/* ring buffer internal formats */
- trace_create_file("header_page", TRACE_MODE_READ, d_events,
+ eventfs_add_top_file("header_page", TRACE_MODE_READ, d_events,
ring_buffer_print_page_header,
&ftrace_show_header_fops);

- trace_create_file("header_event", TRACE_MODE_READ, d_events,
+ eventfs_add_top_file("header_event", TRACE_MODE_READ, d_events,
ring_buffer_print_entry_header,
&ftrace_show_header_fops);

@@ -3755,7 +3758,7 @@ int event_trace_del_tracer(struct trace_array *tr)

down_write(&trace_event_sem);
__trace_remove_event_dirs(tr);
- tracefs_remove(tr->event_dir);
+ eventfs_remove_events_dir(tr->event_dir);
up_write(&trace_event_sem);

tr->event_dir = NULL;
--
2.40.0

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