Commit 24bcc89c authored by Jan Kara's avatar Jan Kara Committed by Theodore Ts'o
Browse files

jbd2: split updating of journal superblock and marking journal empty 



There are three case of updating journal superblock. In the first case, we want
to mark journal as empty (setting s_sequence to 0), in the second case we want
to update log tail, in the third case we want to update s_errno. Split these
cases into separate functions. It makes the code slightly more straightforward
and later patches will make the distinction even more important.

Signed-off-by: default avatarJan Kara <jack@suse.cz>
Signed-off-by: default avatar"Theodore Ts'o" <tytso@mit.edu>
parent 31d4f3a2

fs/jbd2/checkpoint.c

+1 −1
Original line number Diff line number Diff line
@@ -550,7 +550,7 @@ int jbd2_cleanup_journal_tail(journal_t *journal) 
	    (journal->j_flags & JBD2_BARRIER))

		blkdev_issue_flush(journal->j_fs_dev, GFP_KERNEL, NULL);

	if (!(journal->j_flags & JBD2_ABORT))

		jbd2_journal_update_superblock(journal, 1);

		jbd2_journal_update_sb_log_tail(journal);

	return 0;

}

fs/jbd2/commit.c

+1 −1
Original line number Diff line number Diff line
@@ -340,7 +340,7 @@ 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);

		jbd2_journal_update_sb_log_tail(journal);

	} else {

		jbd_debug(3, "superblock not updated\n");

	}

fs/jbd2/journal.c

+95 −68
Original line number Diff line number Diff line
@@ -1110,40 +1110,30 @@ static int journal_reset(journal_t *journal) 


	journal->j_max_transaction_buffers = journal->j_maxlen / 4;



	/* Add the dynamic fields and write it to disk. */

	jbd2_journal_update_superblock(journal, 1);

	return jbd2_journal_start_thread(journal);

}



/**

 * void jbd2_journal_update_superblock() - Update journal sb on disk.

 * @journal: The journal to update.

 * @wait: Set to '0' if you don't want to wait for IO completion.

 *

 * Update a journal's dynamic superblock fields and write it to disk,

 * optionally waiting for the IO to complete.

 */

void jbd2_journal_update_superblock(journal_t *journal, int wait)

{

	journal_superblock_t *sb = journal->j_superblock;

	struct buffer_head *bh = journal->j_sb_buffer;



	/*

	 * As a special case, if the on-disk copy is already marked as needing

	 * no recovery (s_start == 0) and there are no outstanding transactions

	 * in the filesystem, then we can safely defer the superblock update

	 * until the next commit by setting JBD2_FLUSHED.  This avoids

	 * no recovery (s_start == 0), then we can safely defer the superblock

	 * update until the next commit by setting JBD2_FLUSHED.  This avoids

	 * attempting a write to a potential-readonly device.

	 */

	if (sb->s_start == 0 && journal->j_tail_sequence ==

				journal->j_transaction_sequence) {

	if (sb->s_start == 0) {

		jbd_debug(1, "JBD2: Skipping superblock update on recovered sb "

			"(start %ld, seq %d, errno %d)\n",

			journal->j_tail, journal->j_tail_sequence,

			journal->j_errno);

		goto out;

		journal->j_flags |= JBD2_FLUSHED;

	} else {

		/* Add the dynamic fields and write it to disk. */

		jbd2_journal_update_sb_log_tail(journal);

	}

	return jbd2_journal_start_thread(journal);

}



static void jbd2_write_superblock(journal_t *journal)

{

	struct buffer_head *bh = journal->j_sb_buffer;



	trace_jbd2_write_superblock(journal);

	if (buffer_write_io_error(bh)) {

		/*

		 * Oh, dear.  A previous attempt to write the journal
@@ -1160,18 +1150,8 @@ void jbd2_journal_update_superblock(journal_t *journal, int wait) 
		set_buffer_uptodate(bh);

	}



	read_lock(&journal->j_state_lock);

	jbd_debug(1, "JBD2: updating superblock (start %ld, seq %d, errno %d)\n",

		  journal->j_tail, journal->j_tail_sequence, journal->j_errno);



	sb->s_sequence = cpu_to_be32(journal->j_tail_sequence);

	sb->s_start    = cpu_to_be32(journal->j_tail);

	sb->s_errno    = cpu_to_be32(journal->j_errno);

	read_unlock(&journal->j_state_lock);



	BUFFER_TRACE(bh, "marking dirty");

	mark_buffer_dirty(bh);

	if (wait) {

	sync_dirty_buffer(bh);

	if (buffer_write_io_error(bh)) {

		printk(KERN_ERR "JBD2: I/O error detected "
@@ -1180,29 +1160,88 @@ void jbd2_journal_update_superblock(journal_t *journal, int wait) 
		clear_buffer_write_io_error(bh);

		set_buffer_uptodate(bh);

	}

	} else

		write_dirty_buffer(bh, WRITE);

}



	trace_jbd2_update_superblock_end(journal, wait);

/**

 * jbd2_journal_update_sb_log_tail() - Update log tail in journal sb on disk.

 * @journal: The journal to update.

 *

 * Update a journal's superblock information about log tail and write it to

 * disk, waiting for the IO to complete.

 */

void jbd2_journal_update_sb_log_tail(journal_t *journal)

{

	journal_superblock_t *sb = journal->j_superblock;



out:

	/* If we have just flushed the log (by marking s_start==0), then

	 * any future commit will have to be careful to update the

	 * superblock again to re-record the true start of the log. */

	read_lock(&journal->j_state_lock);

	jbd_debug(1, "JBD2: updating superblock (start %ld, seq %d)\n",

		  journal->j_tail, journal->j_tail_sequence);



	sb->s_sequence = cpu_to_be32(journal->j_tail_sequence);

	sb->s_start    = cpu_to_be32(journal->j_tail);

	read_unlock(&journal->j_state_lock);



	jbd2_write_superblock(journal);



	/* Log is no longer empty */

	write_lock(&journal->j_state_lock);

	if (sb->s_start)

	WARN_ON(!sb->s_sequence);

	journal->j_flags &= ~JBD2_FLUSHED;

	else

	write_unlock(&journal->j_state_lock);

}



/**

 * jbd2_mark_journal_empty() - Mark on disk journal as empty.

 * @journal: The journal to update.

 *

 * Update a journal's dynamic superblock fields to show that journal is empty.

 * Write updated superblock to disk waiting for IO to complete.

 */

static void jbd2_mark_journal_empty(journal_t *journal)

{

	journal_superblock_t *sb = journal->j_superblock;



	read_lock(&journal->j_state_lock);

	jbd_debug(1, "JBD2: Marking journal as empty (seq %d)\n",

		  journal->j_tail_sequence);



	sb->s_sequence = cpu_to_be32(journal->j_tail_sequence);

	sb->s_start    = cpu_to_be32(0);

	read_unlock(&journal->j_state_lock);



	jbd2_write_superblock(journal);



	/* Log is no longer empty */

	write_lock(&journal->j_state_lock);

	journal->j_flags |= JBD2_FLUSHED;

	write_unlock(&journal->j_state_lock);

}





/**

 * jbd2_journal_update_sb_errno() - Update error in the journal.

 * @journal: The journal to update.

 *

 * Update a journal's errno.  Write updated superblock to disk waiting for IO

 * to complete.

 */

static void jbd2_journal_update_sb_errno(journal_t *journal)

{

	journal_superblock_t *sb = journal->j_superblock;



	read_lock(&journal->j_state_lock);

	jbd_debug(1, "JBD2: updating superblock error (errno %d)\n",

		  journal->j_errno);

	sb->s_errno    = cpu_to_be32(journal->j_errno);

	read_unlock(&journal->j_state_lock);



	jbd2_write_superblock(journal);

}



/*

 * Read the superblock for a given journal, performing initial

 * validation of the format.

 */



static int journal_get_superblock(journal_t *journal)

{

	struct buffer_head *bh;
@@ -1395,15 +1434,10 @@ int jbd2_journal_destroy(journal_t *journal) 
	spin_unlock(&journal->j_list_lock);



	if (journal->j_sb_buffer) {

		if (!is_journal_aborted(journal)) {

			/* We can now mark the journal as empty. */

			journal->j_tail = 0;

			journal->j_tail_sequence =

				++journal->j_transaction_sequence;

			jbd2_journal_update_superblock(journal, 1);

		} else {

		if (!is_journal_aborted(journal))

			jbd2_mark_journal_empty(journal);

		else

			err = -EIO;

		}

		brelse(journal->j_sb_buffer);

	}
@@ -1562,7 +1596,6 @@ int jbd2_journal_flush(journal_t *journal) 
{

	int err = 0;

	transaction_t *transaction = NULL;

	unsigned long old_tail;



	write_lock(&journal->j_state_lock);
@@ -1604,14 +1637,8 @@ int jbd2_journal_flush(journal_t *journal) 
	 * the magic code for a fully-recovered superblock.  Any future

	 * commits of data to the journal will restore the current

	 * s_start value. */

	jbd2_mark_journal_empty(journal);

	write_lock(&journal->j_state_lock);

	old_tail = journal->j_tail;

	journal->j_tail = 0;

	write_unlock(&journal->j_state_lock);

	jbd2_journal_update_superblock(journal, 1);

	write_lock(&journal->j_state_lock);

	journal->j_tail = old_tail;



	J_ASSERT(!journal->j_running_transaction);

	J_ASSERT(!journal->j_committing_transaction);

	J_ASSERT(!journal->j_checkpoint_transactions);
@@ -1652,7 +1679,7 @@ int jbd2_journal_wipe(journal_t *journal, int write) 


	err = jbd2_journal_skip_recovery(journal);

	if (write)

		jbd2_journal_update_superblock(journal, 1);

		jbd2_mark_journal_empty(journal);



 no_recovery:

	return err;
@@ -1702,7 +1729,7 @@ static void __journal_abort_soft (journal_t *journal, int errno) 
	__jbd2_journal_abort_hard(journal);



	if (errno)

		jbd2_journal_update_superblock(journal, 1);

		jbd2_journal_update_sb_errno(journal);

}



/**

include/linux/jbd2.h

+1 −1
Original line number Diff line number Diff line
@@ -1087,7 +1087,7 @@ extern int jbd2_journal_destroy (journal_t *); 
extern int	   jbd2_journal_recover    (journal_t *journal);

extern int	   jbd2_journal_wipe       (journal_t *, int);

extern int	   jbd2_journal_skip_recovery	(journal_t *);

extern void	   jbd2_journal_update_superblock	(journal_t *, int);

extern void	   jbd2_journal_update_sb_log_tail	(journal_t *);

extern void	   __jbd2_journal_abort_hard	(journal_t *);

extern void	   jbd2_journal_abort      (journal_t *, int);

extern int	   jbd2_journal_errno      (journal_t *);

include/trace/events/jbd2.h

+4 −8
Original line number Diff line number Diff line
@@ -236,25 +236,21 @@ TRACE_EVENT(jbd2_cleanup_journal_tail, 
		  __entry->block_nr, __entry->freed)

);



TRACE_EVENT(jbd2_update_superblock_end,

TRACE_EVENT(jbd2_write_superblock,



	TP_PROTO(journal_t *journal, int wait),

	TP_PROTO(journal_t *journal),



	TP_ARGS(journal, wait),

	TP_ARGS(journal),



	TP_STRUCT__entry(

		__field(	dev_t,  dev			)

		__field(	int,    wait			)

	),



	TP_fast_assign(

		__entry->dev		= journal->j_fs_dev->bd_dev;

		__entry->wait		= wait;

	),



	TP_printk("dev %d,%d wait %d",

		  MAJOR(__entry->dev), MINOR(__entry->dev),

		  __entry->wait)

	TP_printk("dev %d,%d", MAJOR(__entry->dev), MINOR(__entry->dev))

);



#endif /* _TRACE_JBD2_H */

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