+++ /dev/null
-/*
- * ltt/probes/jbd2-trace.c
- *
- * JBD2 tracepoint probes.
- *
- * (C) Copyright 2009 - Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
- * Dual LGPL v2.1/GPL v2 license.
- */
-
-#include <linux/module.h>
-#include <linux/debugfs.h>
-#include <linux/mutex.h>
-#include <linux/rcupdate.h>
-#include <trace/events/jbd2.h>
-
-#include "../ltt-tracer.h"
-
-static struct dentry *jbd2_filter_dentry, *jbd2_filter_dev_dentry;
-static DEFINE_MUTEX(jbd2_filter_mutex);
-/* Make sure we don't race between module exit and file write */
-static int module_exits;
-
-struct rcu_dev_filter {
- struct rcu_head rcu;
- char devname[NAME_MAX];
-};
-
-static struct rcu_dev_filter *dev_filter;
-
-/*
- * Probes are executed in rcu_sched read-side critical section.
- */
-static int do_filter(const char *dev)
-{
- struct rcu_dev_filter *ldev_filter = rcu_dereference(dev_filter);
-
- if (unlikely(ldev_filter))
- if (unlikely(strcmp(ldev_filter->devname, dev)))
- return 0;
- return 1;
-}
-
-void probe_jbd2_checkpoint(void *data, journal_t *journal, int result)
-{
- if (unlikely(!do_filter(journal->j_devname)))
- return;
- trace_mark_tp(jbd2, checkpoint, jbd2_checkpoint,
- probe_jbd2_checkpoint, "dev %s need_checkpoint %d",
- journal->j_devname, result);
-}
-
-void probe_jbd2_start_commit(void *data, journal_t *journal,
- transaction_t *commit_transaction)
-{
- if (unlikely(!do_filter(journal->j_devname)))
- return;
- trace_mark_tp(jbd2, start_commit, jbd2_start_commit,
- probe_jbd2_start_commit, "dev %s transaction %d",
- journal->j_devname, commit_transaction->t_tid);
-}
-
-void probe_jbd2_end_commit(void *data, journal_t *journal,
- transaction_t *commit_transaction)
-{
- if (unlikely(!do_filter(journal->j_devname)))
- return;
- trace_mark_tp(jbd2, end_commit, jbd2_end_commit,
- probe_jbd2_end_commit, "dev %s transaction %d head %d",
- journal->j_devname, commit_transaction->t_tid,
- journal->j_tail_sequence);
-}
-
-static void free_dev_filter(struct rcu_head *head)
-{
- kfree(container_of(head, struct rcu_dev_filter, rcu));
-}
-
-static ssize_t filter_op_write(struct file *file,
- const char __user *user_buf, size_t count, loff_t *ppos)
-{
- int err = 0;
- char buf[NAME_MAX];
- int buf_size;
- char name[NAME_MAX];
- struct rcu_dev_filter *new, *old;
-
- mutex_lock(&jbd2_filter_mutex);
- if (module_exits) {
- err = -EPERM;
- goto error;
- }
- buf_size = min(count, sizeof(buf) - 1);
- err = copy_from_user(buf, user_buf, buf_size);
- if (err)
- goto error;
- buf[buf_size] = 0;
-
- if (sscanf(buf, "%s", name) != 1) {
- err = -EPERM;
- goto error;
- }
-
- old = dev_filter;
-
- /* Empty string or * means all active */
- if (name[0] == '\0' || (name[0] == '*' && name[1] == '\0')) {
- new = NULL;
- } else {
- new = kmalloc(sizeof(*new), GFP_KERNEL);
- strcpy(new->devname, name);
- }
-
- rcu_assign_pointer(dev_filter, new);
- if (old)
- call_rcu_sched(&old->rcu, free_dev_filter);
-
- mutex_unlock(&jbd2_filter_mutex);
- return count;
-
-error:
- mutex_unlock(&jbd2_filter_mutex);
- return err;
-}
-
-static ssize_t filter_op_read(struct file *filp, char __user *buffer,
- size_t count, loff_t *ppos)
-{
- ssize_t bcount;
- const char *devname;
-
- mutex_lock(&jbd2_filter_mutex);
- if (!dev_filter)
- devname = "*";
- else
- devname = dev_filter->devname;
- bcount = simple_read_from_buffer(buffer, count, ppos,
- devname, strlen(devname));
- mutex_unlock(&jbd2_filter_mutex);
- return bcount;
-}
-
-static struct file_operations jbd2_file_operations = {
- .write = filter_op_write,
- .read = filter_op_read,
-};
-
-static void release_filter_dev(void)
-{
- struct rcu_dev_filter *old;
-
- mutex_lock(&jbd2_filter_mutex);
- module_exits = 1;
- old = dev_filter;
- rcu_assign_pointer(dev_filter, NULL);
- if (old)
- call_rcu_sched(&old->rcu, free_dev_filter);
- mutex_unlock(&jbd2_filter_mutex);
-}
-
-static int __init filter_init(void)
-{
- struct dentry *filter_root_dentry;
- int err = 0;
-
- filter_root_dentry = get_filter_root();
- if (!filter_root_dentry) {
- err = -ENOENT;
- goto end;
- }
-
- jbd2_filter_dentry = debugfs_create_dir("jbd2", filter_root_dentry);
-
- if (IS_ERR(jbd2_filter_dentry) || !jbd2_filter_dentry) {
- printk(KERN_ERR "Failed to create jbd2 filter file\n");
- err = -ENOMEM;
- goto end;
- }
-
- jbd2_filter_dev_dentry = debugfs_create_file("dev", S_IWUSR,
- jbd2_filter_dentry, NULL, &jbd2_file_operations);
- if (IS_ERR(jbd2_filter_dentry) || !jbd2_filter_dentry) {
- printk(KERN_ERR "Failed to create jbd2 filter file\n");
- err = -ENOMEM;
- goto release_filter_dentry;
- }
-
- goto end;
-
-release_filter_dentry:
- debugfs_remove(jbd2_filter_dentry);
- release_filter_dev();
-end:
- return err;
-}
-
-static void __exit filter_exit(void)
-{
- debugfs_remove(jbd2_filter_dev_dentry);
- debugfs_remove(jbd2_filter_dentry);
- release_filter_dev();
-}
-
-module_init(filter_init);
-module_exit(filter_exit);
-
-MODULE_LICENSE("GPL and additional rights");
-MODULE_AUTHOR("Mathieu Desnoyers");
-MODULE_DESCRIPTION("JBD2 Tracepoint Probes");
projects / lttng-modules.git / blobdiff