Merge tag 'ext4_for_linus_cleanups' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4

Pull ext4 fixes and cleanups from Ted Ts'o:
 "More fixes and cleanups for the new fast_commit features, but also a
  few other miscellaneous bug fixes and a cleanup for the MAINTAINERS
  file"

* tag 'ext4_for_linus_cleanups' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4: (28 commits)
  jbd2: fix up sparse warnings in checkpoint code
  ext4: fix sparse warnings in fast_commit code
  ext4: cleanup fast commit mount options
  jbd2: don't start fast commit on aborted journal
  ext4: make s_mount_flags modifications atomic
  ext4: issue fsdev cache flush before starting fast commit
  ext4: disable fast commit with data journalling
  ext4: fix inode dirty check in case of fast commits
  ext4: remove unnecessary fast commit calls from ext4_file_mmap
  ext4: mark buf dirty before submitting fast commit buffer
  ext4: fix code documentatioon
  ext4: dedpulicate the code to wait on inode that's being committed
  jbd2: don't read journal->j_commit_sequence without taking a lock
  jbd2: don't touch buffer state until it is filled
  jbd2: add todo for a fast commit performance optimization
  jbd2: don't pass tid to jbd2_fc_end_commit_fallback()
  jbd2: don't use state lock during commit path
  jbd2: drop jbd2_fc_init documentation
  ext4: clean up the JBD2 API that initializes fast commits
  jbd2: rename j_maxlen to j_total_len and add jbd2_journal_max_txn_bufs
  ...

1 files changed, 15 insertions, 8 deletions

diff --git a/include/linux/jbd2.h b/include/linux/jbd2.h
index 1d5566af48ac..1c49fd62ff2e 100644
--- a/include/linux/jbd2.h
+++ b/include/linux/jbd2.h
@@ -68,6 +68,7 @@ extern void *jbd2_alloc(size_t size, gfp_t flags);
 extern void jbd2_free(void *ptr, size_t size);
 
 #define JBD2_MIN_JOURNAL_BLOCKS 1024
+#define JBD2_MIN_FC_BLOCKS	256
 
 #ifdef __KERNEL__
 
@@ -944,8 +945,9 @@ struct journal_s
 	/**
 	 * @j_fc_off:
 	 *
-	 * Number of fast commit blocks currently allocated.
-	 * [j_state_lock].
+	 * Number of fast commit blocks currently allocated. Accessed only
+	 * during fast commit. Currently only process can do fast commit, so
+	 * this field is not protected by any lock.
 	 */
 	unsigned long		j_fc_off;
 
@@ -988,9 +990,9 @@ struct journal_s
 	struct block_device	*j_fs_dev;
 
 	/**
-	 * @j_maxlen: Total maximum capacity of the journal region on disk.
+	 * @j_total_len: Total maximum capacity of the journal region on disk.
 	 */
-	unsigned int		j_maxlen;
+	unsigned int		j_total_len;
 
 	/**
 	 * @j_reserved_credits:
@@ -1108,8 +1110,9 @@ struct journal_s
 	struct buffer_head	**j_wbuf;
 
 	/**
-	 * @j_fc_wbuf: Array of fast commit bhs for
-	 * jbd2_journal_commit_transaction.
+	 * @j_fc_wbuf: Array of fast commit bhs for fast commit. Accessed only
+	 * during a fast commit. Currently only process can do fast commit, so
+	 * this field is not protected by any lock.
 	 */
 	struct buffer_head	**j_fc_wbuf;
 
@@ -1614,16 +1617,20 @@ extern void __jbd2_journal_drop_transaction(journal_t *, transaction_t *);
 extern int jbd2_cleanup_journal_tail(journal_t *);
 
 /* Fast commit related APIs */
-int jbd2_fc_init(journal_t *journal, int num_fc_blks);
 int jbd2_fc_begin_commit(journal_t *journal, tid_t tid);
 int jbd2_fc_end_commit(journal_t *journal);
-int jbd2_fc_end_commit_fallback(journal_t *journal, tid_t tid);
+int jbd2_fc_end_commit_fallback(journal_t *journal);
 int jbd2_fc_get_buf(journal_t *journal, struct buffer_head **bh_out);
 int jbd2_submit_inode_data(struct jbd2_inode *jinode);
 int jbd2_wait_inode_data(journal_t *journal, struct jbd2_inode *jinode);
 int jbd2_fc_wait_bufs(journal_t *journal, int num_blks);
 int jbd2_fc_release_bufs(journal_t *journal);
 
+static inline int jbd2_journal_get_max_txn_bufs(journal_t *journal)
+{
+	return (journal->j_total_len - journal->j_fc_wbufsize) / 4;
+}
+
 /*
  * is_journal_abort
  *