ocfs2: Support commit= mount option

Mostly taken from ext3. This allows the user to set the jbd commit interval,
in seconds. The default of 5 seconds stays the same, but now users can
easily increase the commit interval. Typically, this would be increased in
order to benefit performance at the expense of data-safety.

Signed-off-by: Mark Fasheh <mark.fasheh@oracle.com>

4 files changed, 41 insertions, 2 deletions

diff --git a/Documentation/filesystems/ocfs2.txt b/Documentation/filesystems/ocfs2.txt
index e78abdcc59ee..b63bd2d7fcd3 100644
--- a/Documentation/filesystems/ocfs2.txt
+++ b/Documentation/filesystems/ocfs2.txt
@@ -61,3 +61,14 @@ data=writeback		Data ordering is not preserved, data may be written
 preferred_slot=0(*)     During mount, try to use this filesystem slot first. If
                         it is in use by another node, the first empty one found
                         will be chosen. Invalid values will be ignored.
+commit=nrsec    (*)     Ocfs2 can be told to sync all its data and metadata
+                        every 'nrsec' seconds. The default value is 5 seconds.
+                        This means that if you lose your power, you will lose
+                        as much as the latest 5 seconds of work (your
+                        filesystem will not be damaged though, thanks to the
+                        journaling).  This default value (or any low value)
+                        will hurt performance, but it's good for data-safety.
+                        Setting it to 0 will have the same effect as leaving
+                        it at the default (5 seconds).
+                        Setting it to very large values will improve
+                        performance.
diff --git a/fs/ocfs2/journal.c b/fs/ocfs2/journal.c
index 4f440a88bf53..8b9ce2a729ab 100644
--- a/fs/ocfs2/journal.c
+++ b/fs/ocfs2/journal.c
@@ -313,14 +313,18 @@ int ocfs2_journal_dirty_data(handle_t *handle,
         return err;
 }
 
-#define OCFS2_DEFAULT_COMMIT_INTERVAL   (HZ * 5)
+#define OCFS2_DEFAULT_COMMIT_INTERVAL   (HZ * JBD_DEFAULT_MAX_COMMIT_AGE)
 
 void ocfs2_set_journal_params(struct ocfs2_super *osb)
 {
         journal_t *journal = osb->journal->j_journal;
+        unsigned long commit_interval = OCFS2_DEFAULT_COMMIT_INTERVAL;
+
+        if (osb->osb_commit_interval)
+                commit_interval = osb->osb_commit_interval;
 
         spin_lock(&journal->j_state_lock);
-        journal->j_commit_interval = OCFS2_DEFAULT_COMMIT_INTERVAL;
+        journal->j_commit_interval = commit_interval;
         if (osb->s_mount_opt & OCFS2_MOUNT_BARRIER)
                 journal->j_flags |= JFS_BARRIER;
         else
diff --git a/fs/ocfs2/ocfs2.h b/fs/ocfs2/ocfs2.h
index f8f866144c6a..82802f5672a1 100644
--- a/fs/ocfs2/ocfs2.h
+++ b/fs/ocfs2/ocfs2.h
@@ -229,6 +229,7 @@ struct ocfs2_super
         wait_queue_head_t checkpoint_event;
         atomic_t needs_checkpoint;
         struct ocfs2_journal *journal;
+        unsigned long osb_commit_interval;
 
         enum ocfs2_local_alloc_state local_alloc_state;
         struct buffer_head *local_alloc_bh;
diff --git a/fs/ocfs2/super.c b/fs/ocfs2/super.c
index 479ac50c86d9..8044ed97d362 100644
--- a/fs/ocfs2/super.c
+++ b/fs/ocfs2/super.c
@@ -83,6 +83,7 @@ MODULE_LICENSE("GPL");
 
 struct mount_options
 {
+        unsigned long   commit_interval;
         unsigned long   mount_opt;
         unsigned int    atime_quantum;
         signed short    slot;
@@ -149,6 +150,7 @@ enum {
         Opt_data_writeback,
         Opt_atime_quantum,
         Opt_slot,
+        Opt_commit,
         Opt_err,
 };
 
@@ -164,6 +166,7 @@ static match_table_t tokens = {
         {Opt_data_writeback, "data=writeback"},
         {Opt_atime_quantum, "atime_quantum=%u"},
         {Opt_slot, "preferred_slot=%u"},
+        {Opt_commit, "commit=%u"},
         {Opt_err, NULL}
 };
 
@@ -442,6 +445,8 @@ unlock_osb:
                 osb->s_mount_opt = parsed_options.mount_opt;
                 osb->s_atime_quantum = parsed_options.atime_quantum;
                 osb->preferred_slot = parsed_options.slot;
+                if (parsed_options.commit_interval)
+                        osb->osb_commit_interval = parsed_options.commit_interval;
 
                 if (!ocfs2_is_hard_readonly(osb))
                         ocfs2_set_journal_params(osb);
@@ -596,6 +601,7 @@ static int ocfs2_fill_super(struct super_block *sb, void *data, int silent)
         osb->s_mount_opt = parsed_options.mount_opt;
         osb->s_atime_quantum = parsed_options.atime_quantum;
         osb->preferred_slot = parsed_options.slot;
+        osb->osb_commit_interval = parsed_options.commit_interval;
 
         sb->s_magic = OCFS2_SUPER_MAGIC;
 
@@ -746,6 +752,7 @@ static int ocfs2_parse_options(struct super_block *sb,
         mlog_entry("remount: %d, options: \"%s\"\n", is_remount,
                    options ? options : "(none)");
 
+        mopt->commit_interval = 0;
         mopt->mount_opt = 0;
         mopt->atime_quantum = OCFS2_DEFAULT_ATIME_QUANTUM;
         mopt->slot = OCFS2_INVALID_SLOT;
@@ -815,6 +822,18 @@ static int ocfs2_parse_options(struct super_block *sb,
                         if (option)
                                 mopt->slot = (s16)option;
                         break;
+                case Opt_commit:
+                        option = 0;
+                        if (match_int(&args[0], &option)) {
+                                status = 0;
+                                goto bail;
+                        }
+                        if (option < 0)
+                                return 0;
+                        if (option == 0)
+                                option = JBD_DEFAULT_MAX_COMMIT_AGE;
+                        mopt->commit_interval = HZ * option;
+                        break;
                 default:
                         mlog(ML_ERROR,
                              "Unrecognized mount option \"%s\" "
@@ -863,6 +882,10 @@ static int ocfs2_show_options(struct seq_file *s, struct vfsmount *mnt)
         if (osb->s_atime_quantum != OCFS2_DEFAULT_ATIME_QUANTUM)
                 seq_printf(s, ",atime_quantum=%u", osb->s_atime_quantum);
 
+        if (osb->osb_commit_interval)
+                seq_printf(s, ",commit=%u",
+                           (unsigned) (osb->osb_commit_interval / HZ));
+
         return 0;
 }