Merge tag 'ext4_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4

Pull ext4 updates for 3.4 from Ted Ts'o:
 "Ext4 commits for 3.3 merge window; mostly cleanups and bug fixes

  The changes to export dirty_writeback_interval are from Artem's s_dirt
  cleanup patch series.  The same is true of the change to remove the
  s_dirt helper functions which never got used by anyone in-tree.  I've
  run these changes by Al Viro, and am carrying them so that Artem can
  more easily fix up the rest of the file systems during the next merge
  window.  (Originally we had hopped to remove the use of s_dirt from
  ext4 during this merge window, but his patches had some bugs, so I
  ultimately ended dropping them from the ext4 tree.)"

* tag 'ext4_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4: (66 commits)
  vfs: remove unused superblock helpers
  mm: export dirty_writeback_interval
  ext4: remove useless s_dirt assignment
  ext4: write superblock only once on unmount
  ext4: do not mark superblock as dirty unnecessarily
  ext4: correct ext4_punch_hole return codes
  ext4: remove restrictive checks for EOFBLOCKS_FL
  ext4: always set then trimmed blocks count into len
  ext4: fix trimmed block count accunting
  ext4: fix start and len arguments handling in ext4_trim_fs()
  ext4: update s_free_{inodes,blocks}_count during online resize
  ext4: change some printk() calls to use ext4_msg() instead
  ext4: avoid output message interleaving in ext4_error_<foo>()
  ext4: remove trailing newlines from ext4_msg() and ext4_error() messages
  ext4: add no_printk argument validation, fix fallout
  ext4: remove redundant "EXT4-fs: " from uses of ext4_msg
  ext4: give more helpful error message in ext4_ext_rm_leaf()
  ext4: remove unused code from ext4_ext_map_blocks()
  ext4: rewrite punch hole to use ext4_ext_remove_space()
  jbd2: cleanup journal tail after transaction commit
  ...

1 files changed, 45 insertions, 2 deletions

diff --git a/fs/jbd2/commit.c b/fs/jbd2/commit.c
index c067a8cae63b..17f557f01cf0 100644
--- a/fs/jbd2/commit.c
+++ b/fs/jbd2/commit.c
@@ -331,6 +331,10 @@ void jbd2_journal_commit_transaction(journal_t *journal)
         struct buffer_head *cbh = NULL; /* For transactional checksums */
         __u32 crc32_sum = ~0;
         struct blk_plug plug;
+        /* Tail of the journal */
+        unsigned long first_block;
+        tid_t first_tid;
+        int update_tail;
 
         /*
          * First job: lock down the current transaction and wait for
@@ -340,7 +344,18 @@ void jbd2_journal_commit_transaction(journal_t *journal)
         /* Do we need to erase the effects of a prior jbd2_journal_flush? */
         if (journal->j_flags & JBD2_FLUSHED) {
                 jbd_debug(3, "super block updated\n");
-                jbd2_journal_update_superblock(journal, 1);
+                mutex_lock(&journal->j_checkpoint_mutex);
+                /*
+                 * We hold j_checkpoint_mutex so tail cannot change under us.
+                 * We don't need any special data guarantees for writing sb
+                 * since journal is empty and it is ok for write to be
+                 * flushed only with transaction commit.
+                 */
+                jbd2_journal_update_sb_log_tail(journal,
+                                                journal->j_tail_sequence,
+                                                journal->j_tail,
+                                                WRITE_SYNC);
+                mutex_unlock(&journal->j_checkpoint_mutex);
         } else {
                 jbd_debug(3, "superblock not updated\n");
         }
@@ -677,10 +692,30 @@ start_journal_io:
                 err = 0;
         }
 
+        /*
+         * Get current oldest transaction in the log before we issue flush
+         * to the filesystem device. After the flush we can be sure that
+         * blocks of all older transactions are checkpointed to persistent
+         * storage and we will be safe to update journal start in the
+         * superblock with the numbers we get here.
+         */
+        update_tail =
+                jbd2_journal_get_log_tail(journal, &first_tid, &first_block);
+
         write_lock(&journal->j_state_lock);
+        if (update_tail) {
+                long freed = first_block - journal->j_tail;
+
+                if (first_block < journal->j_tail)
+                        freed += journal->j_last - journal->j_first;
+                /* Update tail only if we free significant amount of space */
+                if (freed < journal->j_maxlen / 4)
+                        update_tail = 0;
+        }
         J_ASSERT(commit_transaction->t_state == T_COMMIT);
         commit_transaction->t_state = T_COMMIT_DFLUSH;
         write_unlock(&journal->j_state_lock);
+
         /* 
          * If the journal is not located on the file system device,
          * then we must flush the file system device before we issue
@@ -831,6 +866,14 @@ wait_for_iobuf:
         if (err)
                 jbd2_journal_abort(journal, err);
 
+        /*
+         * Now disk caches for filesystem device are flushed so we are safe to
+         * erase checkpointed transactions from the log by updating journal
+         * superblock.
+         */
+        if (update_tail)
+                jbd2_update_log_tail(journal, first_tid, first_block);
+
         /* End of a transaction!  Finally, we can do checkpoint
            processing: any buffers committed as a result of this
            transaction can be removed from any checkpoint list it was on
@@ -1048,7 +1091,7 @@ restart_loop:
         jbd_debug(1, "JBD2: commit %d complete, head %d\n",
                   journal->j_commit_sequence, journal->j_tail_sequence);
         if (to_free)
-                kfree(commit_transaction);
+                jbd2_journal_free_transaction(commit_transaction);
 
         wake_up(&journal->j_wait_done_commit);
 }