jbd2: Implement data=ordered mode handling via inodes

This patch adds necessary framework into JBD2 to be able to track inodes
with each transaction and write-out their dirty data during transaction
commit time.

This new ordered mode brings all sorts of advantages such as possibility 
to get rid of journal heads and buffer heads for data buffers in ordered 
mode, better ordering of writes on transaction commit, simplification of
 some JBD code, no more anonymous pages when truncate of data being 
committed happens.  Also with this new ordered mode, delayed allocation 
on ordered mode is much simpler.

Signed-off-by: Jan Kara <jack@suse.cz>

1 files changed, 42 insertions, 0 deletions

diff --git a/include/linux/jbd2.h b/include/linux/jbd2.h
index ec9cadf58227..622c3d8ca4ed 100644
--- a/include/linux/jbd2.h
+++ b/include/linux/jbd2.h
@@ -381,6 +381,38 @@ static inline void jbd_unlock_bh_journal_head(struct buffer_head *bh)
         bit_spin_unlock(BH_JournalHead, &bh->b_state);
 }
 
+/* Flags in jbd_inode->i_flags */
+#define __JI_COMMIT_RUNNING 0
+/* Commit of the inode data in progress. We use this flag to protect us from
+ * concurrent deletion of inode. We cannot use reference to inode for this
+ * since we cannot afford doing last iput() on behalf of kjournald
+ */
+#define JI_COMMIT_RUNNING (1 << __JI_COMMIT_RUNNING)
+
+/**
+ * struct jbd_inode is the structure linking inodes in ordered mode
+ *   present in a transaction so that we can sync them during commit.
+ */
+struct jbd2_inode {
+        /* Which transaction does this inode belong to? Either the running
+         * transaction or the committing one. [j_list_lock] */
+        transaction_t *i_transaction;
+
+        /* Pointer to the running transaction modifying inode's data in case
+         * there is already a committing transaction touching it. [j_list_lock] */
+        transaction_t *i_next_transaction;
+
+        /* List of inodes in the i_transaction [j_list_lock] */
+        struct list_head i_list;
+
+        /* VFS inode this inode belongs to [constant during the lifetime
+         * of the structure] */
+        struct inode *i_vfs_inode;
+
+        /* Flags of inode [j_list_lock] */
+        unsigned int i_flags;
+};
+
 struct jbd2_revoke_table_s;
 
 /**
@@ -567,6 +599,12 @@ struct transaction_s
         struct journal_head     *t_log_list;
 
         /*
+         * List of inodes whose data we've modified in data=ordered mode.
+         * [j_list_lock]
+         */
+        struct list_head        t_inode_list;
+
+        /*
          * Protects info related to handles
          */
         spinlock_t              t_handle_lock;
@@ -1046,6 +1084,10 @@ extern void	   jbd2_journal_ack_err    (journal_t *);
 extern int         jbd2_journal_clear_err  (journal_t *);
 extern int         jbd2_journal_bmap(journal_t *, unsigned long, unsigned long long *);
 extern int         jbd2_journal_force_commit(journal_t *);
+extern int         jbd2_journal_file_inode(handle_t *handle, struct jbd2_inode *inode);
+extern int         jbd2_journal_begin_ordered_truncate(struct jbd2_inode *inode, loff_t new_size);
+extern void        jbd2_journal_init_jbd_inode(struct jbd2_inode *jinode, struct inode *inode);
+extern void        jbd2_journal_release_jbd_inode(journal_t *journal, struct jbd2_inode *jinode);
 
 /*
  * journal_head management