#include <linux/slab.h>
 #include <linux/mm.h>
 #include <linux/pagemap.h>
+#include <linux/jiffies.h>
 
 /*
  * Default IO end handler for temporary BJ_IO buffer_heads.
  */
 void jbd2_journal_commit_transaction(journal_t *journal)
 {
+       struct transaction_stats_s stats;
        transaction_t *commit_transaction;
        struct journal_head *jh, *new_jh, *descriptor;
        struct buffer_head **wbuf = journal->j_wbuf;
        spin_lock(&journal->j_state_lock);
        commit_transaction->t_state = T_LOCKED;
 
+       stats.u.run.rs_wait = commit_transaction->t_max_wait;
+       stats.u.run.rs_locked = jiffies;
+       stats.u.run.rs_running = jbd2_time_diff(commit_transaction->t_start,
+                                               stats.u.run.rs_locked);
+
        spin_lock(&commit_transaction->t_handle_lock);
        while (commit_transaction->t_updates) {
                DEFINE_WAIT(wait);
         */
        jbd2_journal_switch_revoke_table(journal);
 
+       stats.u.run.rs_flushing = jiffies;
+       stats.u.run.rs_locked = jbd2_time_diff(stats.u.run.rs_locked,
+                                              stats.u.run.rs_flushing);
+
        commit_transaction->t_state = T_FLUSH;
        journal->j_committing_transaction = commit_transaction;
        journal->j_running_transaction = NULL;
         */
        commit_transaction->t_state = T_COMMIT;
 
+       stats.u.run.rs_logging = jiffies;
+       stats.u.run.rs_flushing = jbd2_time_diff(stats.u.run.rs_flushing,
+                                                stats.u.run.rs_logging);
+       stats.u.run.rs_blocks = commit_transaction->t_outstanding_credits;
+       stats.u.run.rs_blocks_logged = 0;
+
        descriptor = NULL;
        bufs = 0;
        while (commit_transaction->t_buffers) {
                                submit_bh(WRITE, bh);
                        }
                        cond_resched();
+                       stats.u.run.rs_blocks_logged += bufs;
 
                        /* Force a new descriptor to be generated next
                            time round the loop. */
                cp_transaction = jh->b_cp_transaction;
                if (cp_transaction) {
                        JBUFFER_TRACE(jh, "remove from old cp transaction");
+                       cp_transaction->t_chp_stats.cs_dropped++;
                        __jbd2_journal_remove_checkpoint(jh);
                }
 
 
        J_ASSERT(commit_transaction->t_state == T_COMMIT);
 
+       commit_transaction->t_start = jiffies;
+       stats.u.run.rs_logging = jbd2_time_diff(stats.u.run.rs_logging,
+                                               commit_transaction->t_start);
+
+       /*
+        * File the transaction for history
+        */
+       stats.ts_type = JBD2_STATS_RUN;
+       stats.ts_tid = commit_transaction->t_tid;
+       stats.u.run.rs_handle_count = commit_transaction->t_handle_count;
+       spin_lock(&journal->j_history_lock);
+       memcpy(journal->j_history + journal->j_history_cur, &stats,
+                       sizeof(stats));
+       if (++journal->j_history_cur == journal->j_history_max)
+               journal->j_history_cur = 0;
+
+       /*
+        * Calculate overall stats
+        */
+       journal->j_stats.ts_tid++;
+       journal->j_stats.u.run.rs_wait += stats.u.run.rs_wait;
+       journal->j_stats.u.run.rs_running += stats.u.run.rs_running;
+       journal->j_stats.u.run.rs_locked += stats.u.run.rs_locked;
+       journal->j_stats.u.run.rs_flushing += stats.u.run.rs_flushing;
+       journal->j_stats.u.run.rs_logging += stats.u.run.rs_logging;
+       journal->j_stats.u.run.rs_handle_count += stats.u.run.rs_handle_count;
+       journal->j_stats.u.run.rs_blocks += stats.u.run.rs_blocks;
+       journal->j_stats.u.run.rs_blocks_logged += stats.u.run.rs_blocks_logged;
+       spin_unlock(&journal->j_history_lock);
+
        commit_transaction->t_state = T_FINISHED;
        J_ASSERT(commit_transaction == journal->j_committing_transaction);
        journal->j_commit_sequence = commit_transaction->t_tid;
 
 #include <linux/poison.h>
 #include <linux/proc_fs.h>
 #include <linux/debugfs.h>
+#include <linux/seq_file.h>
 
 #include <asm/uaccess.h>
 #include <asm/page.h>
        return jbd2_journal_add_journal_head(bh);
 }
 
+struct jbd2_stats_proc_session {
+       journal_t *journal;
+       struct transaction_stats_s *stats;
+       int start;
+       int max;
+};
+
+static void *jbd2_history_skip_empty(struct jbd2_stats_proc_session *s,
+                                       struct transaction_stats_s *ts,
+                                       int first)
+{
+       if (ts == s->stats + s->max)
+               ts = s->stats;
+       if (!first && ts == s->stats + s->start)
+               return NULL;
+       while (ts->ts_type == 0) {
+               ts++;
+               if (ts == s->stats + s->max)
+                       ts = s->stats;
+               if (ts == s->stats + s->start)
+                       return NULL;
+       }
+       return ts;
+
+}
+
+static void *jbd2_seq_history_start(struct seq_file *seq, loff_t *pos)
+{
+       struct jbd2_stats_proc_session *s = seq->private;
+       struct transaction_stats_s *ts;
+       int l = *pos;
+
+       if (l == 0)
+               return SEQ_START_TOKEN;
+       ts = jbd2_history_skip_empty(s, s->stats + s->start, 1);
+       if (!ts)
+               return NULL;
+       l--;
+       while (l) {
+               ts = jbd2_history_skip_empty(s, ++ts, 0);
+               if (!ts)
+                       break;
+               l--;
+       }
+       return ts;
+}
+
+static void *jbd2_seq_history_next(struct seq_file *seq, void *v, loff_t *pos)
+{
+       struct jbd2_stats_proc_session *s = seq->private;
+       struct transaction_stats_s *ts = v;
+
+       ++*pos;
+       if (v == SEQ_START_TOKEN)
+               return jbd2_history_skip_empty(s, s->stats + s->start, 1);
+       else
+               return jbd2_history_skip_empty(s, ++ts, 0);
+}
+
+static int jbd2_seq_history_show(struct seq_file *seq, void *v)
+{
+       struct transaction_stats_s *ts = v;
+       if (v == SEQ_START_TOKEN) {
+               seq_printf(seq, "%-4s %-5s %-5s %-5s %-5s %-5s %-5s %-6s %-5s "
+                               "%-5s %-5s %-5s %-5s %-5s\n", "R/C", "tid",
+                               "wait", "run", "lock", "flush", "log", "hndls",
+                               "block", "inlog", "ctime", "write", "drop",
+                               "close");
+               return 0;
+       }
+       if (ts->ts_type == JBD2_STATS_RUN)
+               seq_printf(seq, "%-4s %-5lu %-5u %-5u %-5u %-5u %-5u "
+                               "%-6lu %-5lu %-5lu\n", "R", ts->ts_tid,
+                               jiffies_to_msecs(ts->u.run.rs_wait),
+                               jiffies_to_msecs(ts->u.run.rs_running),
+                               jiffies_to_msecs(ts->u.run.rs_locked),
+                               jiffies_to_msecs(ts->u.run.rs_flushing),
+                               jiffies_to_msecs(ts->u.run.rs_logging),
+                               ts->u.run.rs_handle_count,
+                               ts->u.run.rs_blocks,
+                               ts->u.run.rs_blocks_logged);
+       else if (ts->ts_type == JBD2_STATS_CHECKPOINT)
+               seq_printf(seq, "%-4s %-5lu %48s %-5u %-5lu %-5lu %-5lu\n",
+                               "C", ts->ts_tid, " ",
+                               jiffies_to_msecs(ts->u.chp.cs_chp_time),
+                               ts->u.chp.cs_written, ts->u.chp.cs_dropped,
+                               ts->u.chp.cs_forced_to_close);
+       else
+               J_ASSERT(0);
+       return 0;
+}
+
+static void jbd2_seq_history_stop(struct seq_file *seq, void *v)
+{
+}
+
+static struct seq_operations jbd2_seq_history_ops = {
+       .start  = jbd2_seq_history_start,
+       .next   = jbd2_seq_history_next,
+       .stop   = jbd2_seq_history_stop,
+       .show   = jbd2_seq_history_show,
+};
+
+static int jbd2_seq_history_open(struct inode *inode, struct file *file)
+{
+       journal_t *journal = PDE(inode)->data;
+       struct jbd2_stats_proc_session *s;
+       int rc, size;
+
+       s = kmalloc(sizeof(*s), GFP_KERNEL);
+       if (s == NULL)
+               return -ENOMEM;
+       size = sizeof(struct transaction_stats_s) * journal->j_history_max;
+       s->stats = kmalloc(size, GFP_KERNEL);
+       if (s->stats == NULL) {
+               kfree(s);
+               return -ENOMEM;
+       }
+       spin_lock(&journal->j_history_lock);
+       memcpy(s->stats, journal->j_history, size);
+       s->max = journal->j_history_max;
+       s->start = journal->j_history_cur % s->max;
+       spin_unlock(&journal->j_history_lock);
+
+       rc = seq_open(file, &jbd2_seq_history_ops);
+       if (rc == 0) {
+               struct seq_file *m = file->private_data;
+               m->private = s;
+       } else {
+               kfree(s->stats);
+               kfree(s);
+       }
+       return rc;
+
+}
+
+static int jbd2_seq_history_release(struct inode *inode, struct file *file)
+{
+       struct seq_file *seq = file->private_data;
+       struct jbd2_stats_proc_session *s = seq->private;
+
+       kfree(s->stats);
+       kfree(s);
+       return seq_release(inode, file);
+}
+
+static struct file_operations jbd2_seq_history_fops = {
+       .owner          = THIS_MODULE,
+       .open           = jbd2_seq_history_open,
+       .read           = seq_read,
+       .llseek         = seq_lseek,
+       .release        = jbd2_seq_history_release,
+};
+
+static void *jbd2_seq_info_start(struct seq_file *seq, loff_t *pos)
+{
+       return *pos ? NULL : SEQ_START_TOKEN;
+}
+
+static void *jbd2_seq_info_next(struct seq_file *seq, void *v, loff_t *pos)
+{
+       return NULL;
+}
+
+static int jbd2_seq_info_show(struct seq_file *seq, void *v)
+{
+       struct jbd2_stats_proc_session *s = seq->private;
+
+       if (v != SEQ_START_TOKEN)
+               return 0;
+       seq_printf(seq, "%lu transaction, each upto %u blocks\n",
+                       s->stats->ts_tid,
+                       s->journal->j_max_transaction_buffers);
+       if (s->stats->ts_tid == 0)
+               return 0;
+       seq_printf(seq, "average: \n  %ums waiting for transaction\n",
+           jiffies_to_msecs(s->stats->u.run.rs_wait / s->stats->ts_tid));
+       seq_printf(seq, "  %ums running transaction\n",
+           jiffies_to_msecs(s->stats->u.run.rs_running / s->stats->ts_tid));
+       seq_printf(seq, "  %ums transaction was being locked\n",
+           jiffies_to_msecs(s->stats->u.run.rs_locked / s->stats->ts_tid));
+       seq_printf(seq, "  %ums flushing data (in ordered mode)\n",
+           jiffies_to_msecs(s->stats->u.run.rs_flushing / s->stats->ts_tid));
+       seq_printf(seq, "  %ums logging transaction\n",
+           jiffies_to_msecs(s->stats->u.run.rs_logging / s->stats->ts_tid));
+       seq_printf(seq, "  %lu handles per transaction\n",
+           s->stats->u.run.rs_handle_count / s->stats->ts_tid);
+       seq_printf(seq, "  %lu blocks per transaction\n",
+           s->stats->u.run.rs_blocks / s->stats->ts_tid);
+       seq_printf(seq, "  %lu logged blocks per transaction\n",
+           s->stats->u.run.rs_blocks_logged / s->stats->ts_tid);
+       return 0;
+}
+
+static void jbd2_seq_info_stop(struct seq_file *seq, void *v)
+{
+}
+
+static struct seq_operations jbd2_seq_info_ops = {
+       .start  = jbd2_seq_info_start,
+       .next   = jbd2_seq_info_next,
+       .stop   = jbd2_seq_info_stop,
+       .show   = jbd2_seq_info_show,
+};
+
+static int jbd2_seq_info_open(struct inode *inode, struct file *file)
+{
+       journal_t *journal = PDE(inode)->data;
+       struct jbd2_stats_proc_session *s;
+       int rc, size;
+
+       s = kmalloc(sizeof(*s), GFP_KERNEL);
+       if (s == NULL)
+               return -ENOMEM;
+       size = sizeof(struct transaction_stats_s);
+       s->stats = kmalloc(size, GFP_KERNEL);
+       if (s->stats == NULL) {
+               kfree(s);
+               return -ENOMEM;
+       }
+       spin_lock(&journal->j_history_lock);
+       memcpy(s->stats, &journal->j_stats, size);
+       s->journal = journal;
+       spin_unlock(&journal->j_history_lock);
+
+       rc = seq_open(file, &jbd2_seq_info_ops);
+       if (rc == 0) {
+               struct seq_file *m = file->private_data;
+               m->private = s;
+       } else {
+               kfree(s->stats);
+               kfree(s);
+       }
+       return rc;
+
+}
+
+static int jbd2_seq_info_release(struct inode *inode, struct file *file)
+{
+       struct seq_file *seq = file->private_data;
+       struct jbd2_stats_proc_session *s = seq->private;
+       kfree(s->stats);
+       kfree(s);
+       return seq_release(inode, file);
+}
+
+static struct file_operations jbd2_seq_info_fops = {
+       .owner          = THIS_MODULE,
+       .open           = jbd2_seq_info_open,
+       .read           = seq_read,
+       .llseek         = seq_lseek,
+       .release        = jbd2_seq_info_release,
+};
+
+static struct proc_dir_entry *proc_jbd2_stats;
+
+static void jbd2_stats_proc_init(journal_t *journal)
+{
+       char name[BDEVNAME_SIZE];
+
+       snprintf(name, sizeof(name) - 1, "%s", bdevname(journal->j_dev, name));
+       journal->j_proc_entry = proc_mkdir(name, proc_jbd2_stats);
+       if (journal->j_proc_entry) {
+               struct proc_dir_entry *p;
+               p = create_proc_entry("history", S_IRUGO,
+                               journal->j_proc_entry);
+               if (p) {
+                       p->proc_fops = &jbd2_seq_history_fops;
+                       p->data = journal;
+                       p = create_proc_entry("info", S_IRUGO,
+                                               journal->j_proc_entry);
+                       if (p) {
+                               p->proc_fops = &jbd2_seq_info_fops;
+                               p->data = journal;
+                       }
+               }
+       }
+}
+
+static void jbd2_stats_proc_exit(journal_t *journal)
+{
+       char name[BDEVNAME_SIZE];
+
+       snprintf(name, sizeof(name) - 1, "%s", bdevname(journal->j_dev, name));
+       remove_proc_entry("info", journal->j_proc_entry);
+       remove_proc_entry("history", journal->j_proc_entry);
+       remove_proc_entry(name, proc_jbd2_stats);
+}
+
+static void journal_init_stats(journal_t *journal)
+{
+       int size;
+
+       if (!proc_jbd2_stats)
+               return;
+
+       journal->j_history_max = 100;
+       size = sizeof(struct transaction_stats_s) * journal->j_history_max;
+       journal->j_history = kzalloc(size, GFP_KERNEL);
+       if (!journal->j_history) {
+               journal->j_history_max = 0;
+               return;
+       }
+       spin_lock_init(&journal->j_history_lock);
+}
+
 /*
  * Management for journal control blocks: functions to create and
  * destroy journal_t structures, and to initialise and read existing
                kfree(journal);
                goto fail;
        }
+
+       journal_init_stats(journal);
+
        return journal;
 fail:
        return NULL;
        journal->j_fs_dev = fs_dev;
        journal->j_blk_offset = start;
        journal->j_maxlen = len;
+       jbd2_stats_proc_init(journal);
 
        bh = __getblk(journal->j_dev, start, journal->j_blocksize);
        J_ASSERT(bh != NULL);
 
        journal->j_maxlen = inode->i_size >> inode->i_sb->s_blocksize_bits;
        journal->j_blocksize = inode->i_sb->s_blocksize;
+       jbd2_stats_proc_init(journal);
 
        /* journal descriptor can store up to n blocks -bzzz */
        n = journal->j_blocksize / sizeof(journal_block_tag_t);
                brelse(journal->j_sb_buffer);
        }
 
+       if (journal->j_proc_entry)
+               jbd2_stats_proc_exit(journal);
        if (journal->j_inode)
                iput(journal->j_inode);
        if (journal->j_revoke)
 
 #endif
 
+#ifdef CONFIG_PROC_FS
+
+#define JBD2_STATS_PROC_NAME "fs/jbd2"
+
+static void __init jbd2_create_jbd_stats_proc_entry(void)
+{
+       proc_jbd2_stats = proc_mkdir(JBD2_STATS_PROC_NAME, NULL);
+}
+
+static void __exit jbd2_remove_jbd_stats_proc_entry(void)
+{
+       if (proc_jbd2_stats)
+               remove_proc_entry(JBD2_STATS_PROC_NAME, NULL);
+}
+
+#else
+
+#define jbd2_create_jbd_stats_proc_entry() do {} while (0)
+#define jbd2_remove_jbd_stats_proc_entry() do {} while (0)
+
+#endif
+
 struct kmem_cache *jbd2_handle_cache;
 
 static int __init journal_init_handle_cache(void)
        if (ret != 0)
                jbd2_journal_destroy_caches();
        jbd2_create_debugfs_entry();
+       jbd2_create_jbd_stats_proc_entry();
        return ret;
 }
 
                printk(KERN_EMERG "JBD: leaked %d journal_heads!\n", n);
 #endif
        jbd2_remove_debugfs_entry();
+       jbd2_remove_jbd_stats_proc_entry();
        jbd2_journal_destroy_caches();
 }
 
 
 };
 
 
+/*
+ * Some stats for checkpoint phase
+ */
+struct transaction_chp_stats_s {
+       unsigned long           cs_chp_time;
+       unsigned long           cs_forced_to_close;
+       unsigned long           cs_written;
+       unsigned long           cs_dropped;
+};
+
 /* The transaction_t type is the guts of the journaling mechanism.  It
  * tracks a compound transaction through its various states:
  *
         */
        spinlock_t              t_handle_lock;
 
+       /*
+        * Longest time some handle had to wait for running transaction
+        */
+       unsigned long           t_max_wait;
+
+       /*
+        * When transaction started
+        */
+       unsigned long           t_start;
+
+       /*
+        * Checkpointing stats [j_checkpoint_sem]
+        */
+       struct transaction_chp_stats_s t_chp_stats;
+
        /*
         * Number of outstanding updates running on this transaction
         * [t_handle_lock]
 
 };
 
+struct transaction_run_stats_s {
+       unsigned long           rs_wait;
+       unsigned long           rs_running;
+       unsigned long           rs_locked;
+       unsigned long           rs_flushing;
+       unsigned long           rs_logging;
+
+       unsigned long           rs_handle_count;
+       unsigned long           rs_blocks;
+       unsigned long           rs_blocks_logged;
+};
+
+struct transaction_stats_s {
+       int                     ts_type;
+       unsigned long           ts_tid;
+       union {
+               struct transaction_run_stats_s run;
+               struct transaction_chp_stats_s chp;
+       } u;
+};
+
+#define JBD2_STATS_RUN         1
+#define JBD2_STATS_CHECKPOINT  2
+
+static inline unsigned long
+jbd2_time_diff(unsigned long start, unsigned long end)
+{
+       if (end >= start)
+               return end - start;
+
+       return end + (MAX_JIFFY_OFFSET - start);
+}
+
 /**
  * struct journal_s - The journal_s type is the concrete type associated with
  *     journal_t.
  * @j_wbufsize: maximum number of buffer_heads allowed in j_wbuf, the
  *     number that will fit in j_blocksize
  * @j_last_sync_writer: most recent pid which did a synchronous write
+ * @j_history: Buffer storing the transactions statistics history
+ * @j_history_max: Maximum number of transactions in the statistics history
+ * @j_history_cur: Current number of transactions in the statistics history
+ * @j_history_lock: Protect the transactions statistics history
+ * @j_proc_entry: procfs entry for the jbd statistics directory
+ * @j_stats: Overall statistics
  * @j_private: An opaque pointer to fs-private information.
  */
 
 
        pid_t                   j_last_sync_writer;
 
+       /*
+        * Journal statistics
+        */
+       struct transaction_stats_s *j_history;
+       int                     j_history_max;
+       int                     j_history_cur;
+       /*
+        * Protect the transactions statistics history
+        */
+       spinlock_t              j_history_lock;
+       struct proc_dir_entry   *j_proc_entry;
+       struct transaction_stats_s j_stats;
+
        /*
         * An opaque pointer to fs-private information.  ext3 puts its
         * superblock pointer here