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Date: Wed, 11 Apr 2012 21:58:36 +0200
From: Jan Kara <jack@...e.cz>
To: linux-ext4@...r.kernel.org
Cc: Jan Kara <jack@...e.cz>
Subject: [PATCH 1/3] jbd: 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: Jan Kara <jack@...e.cz>
---
fs/jbd/checkpoint.c | 2 +-
fs/jbd/commit.c | 2 +-
fs/jbd/journal.c | 164 ++++++++++++++++++++++++++------------------
include/linux/jbd.h | 2 +-
include/trace/events/jbd.h | 12 +--
5 files changed, 104 insertions(+), 78 deletions(-)
diff --git a/fs/jbd/checkpoint.c b/fs/jbd/checkpoint.c
index 05f0754..80c85f3 100644
--- a/fs/jbd/checkpoint.c
+++ b/fs/jbd/checkpoint.c
@@ -540,7 +540,7 @@ int cleanup_journal_tail(journal_t *journal)
journal->j_tail = blocknr;
spin_unlock(&journal->j_state_lock);
if (!(journal->j_flags & JFS_ABORT))
- journal_update_superblock(journal, 1);
+ journal_update_sb_log_tail(journal);
return 0;
}
diff --git a/fs/jbd/commit.c b/fs/jbd/commit.c
index 9d31e6a..dba9cfd 100644
--- a/fs/jbd/commit.c
+++ b/fs/jbd/commit.c
@@ -308,7 +308,7 @@ void journal_commit_transaction(journal_t *journal)
/* Do we need to erase the effects of a prior journal_flush? */
if (journal->j_flags & JFS_FLUSHED) {
jbd_debug(3, "super block updated\n");
- journal_update_superblock(journal, 1);
+ journal_update_sb_log_tail(journal);
} else {
jbd_debug(3, "superblock not updated\n");
}
diff --git a/fs/jbd/journal.c b/fs/jbd/journal.c
index 2047fd7..44c104a 100644
--- a/fs/jbd/journal.c
+++ b/fs/jbd/journal.c
@@ -923,8 +923,22 @@ 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. */
- journal_update_superblock(journal, 1);
+ /*
+ * As a special case, if the on-disk copy is already marked as needing
+ * no recovery (s_start == 0), then we can safely defer the superblock
+ * update until the next commit by setting JFS_FLUSHED. This avoids
+ * attempting a write to a potential-readonly device.
+ */
+ if (sb->s_start == 0) {
+ jbd_debug(1,"JBD: Skipping superblock update on recovered sb "
+ "(start %u, seq %d, errno %d)\n",
+ journal->j_tail, journal->j_tail_sequence,
+ journal->j_errno);
+ journal->j_flags |= JFS_FLUSHED;
+ } else {
+ /* Add the dynamic fields and write it to disk. */
+ journal_update_sb_log_tail(journal);
+ }
return journal_start_thread(journal);
}
@@ -1001,35 +1015,11 @@ int journal_create(journal_t *journal)
return journal_reset(journal);
}
-/**
- * void 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 journal_update_superblock(journal_t *journal, int wait)
+static void journal_write_superblock(journal_t *journal)
{
- 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 JFS_FLUSHED. This avoids
- * attempting a write to a potential-readonly device.
- */
- if (sb->s_start == 0 && journal->j_tail_sequence ==
- journal->j_transaction_sequence) {
- jbd_debug(1,"JBD: Skipping superblock update on recovered sb "
- "(start %u, seq %d, errno %d)\n",
- journal->j_tail, journal->j_tail_sequence,
- journal->j_errno);
- goto out;
- }
-
+ trace_journal_write_superblock(journal);
if (buffer_write_io_error(bh)) {
char b[BDEVNAME_SIZE];
/*
@@ -1047,44 +1037,94 @@ void journal_update_superblock(journal_t *journal, int wait)
set_buffer_uptodate(bh);
}
+ BUFFER_TRACE(bh, "marking dirty");
+ mark_buffer_dirty(bh);
+ sync_dirty_buffer(bh);
+ if (buffer_write_io_error(bh)) {
+ char b[BDEVNAME_SIZE];
+ printk(KERN_ERR "JBD: I/O error detected "
+ "when updating journal superblock for %s.\n",
+ journal_dev_name(journal, b));
+ clear_buffer_write_io_error(bh);
+ set_buffer_uptodate(bh);
+ }
+}
+
+/**
+ * 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 journal_update_sb_log_tail(journal_t *journal)
+{
+ journal_superblock_t *sb = journal->j_superblock;
+
spin_lock(&journal->j_state_lock);
jbd_debug(1,"JBD: updating superblock (start %u, 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);
spin_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)) {
- char b[BDEVNAME_SIZE];
- printk(KERN_ERR "JBD: I/O error detected "
- "when updating journal superblock for %s.\n",
- journal_dev_name(journal, b));
- clear_buffer_write_io_error(bh);
- set_buffer_uptodate(bh);
- }
- } else
- write_dirty_buffer(bh, WRITE);
+ journal_write_superblock(journal);
- trace_jbd_update_superblock_end(journal, wait);
-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. */
+ /* Log is no longer empty */
+ spin_lock(&journal->j_state_lock);
+ WARN_ON(!sb->s_sequence);
+ journal->j_flags &= ~JFS_FLUSHED;
+ spin_unlock(&journal->j_state_lock);
+}
+
+/**
+ * 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 mark_journal_empty(journal_t *journal)
+{
+ journal_superblock_t *sb = journal->j_superblock;
spin_lock(&journal->j_state_lock);
- if (sb->s_start)
- journal->j_flags &= ~JFS_FLUSHED;
- else
- journal->j_flags |= JFS_FLUSHED;
+ jbd_debug(1, "JBD: 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);
+ spin_unlock(&journal->j_state_lock);
+
+ journal_write_superblock(journal);
+
+ spin_lock(&journal->j_state_lock);
+ /* Log is empty */
+ journal->j_flags |= JFS_FLUSHED;
spin_unlock(&journal->j_state_lock);
}
+/**
+ * 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 journal_update_sb_errno(journal_t *journal)
+{
+ journal_superblock_t *sb = journal->j_superblock;
+
+ spin_lock(&journal->j_state_lock);
+ jbd_debug(1, "JBD: updating superblock error (errno %d)\n",
+ journal->j_errno);
+ sb->s_errno = cpu_to_be32(journal->j_errno);
+ spin_unlock(&journal->j_state_lock);
+
+ journal_write_superblock(journal);
+}
+
/*
* Read the superblock for a given journal, performing initial
* validation of the format.
@@ -1268,14 +1308,11 @@ int journal_destroy(journal_t *journal)
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;
- journal_update_superblock(journal, 1);
- } else {
+ mark_journal_empty(journal);
+ } else
err = -EIO;
- }
brelse(journal->j_sb_buffer);
}
@@ -1457,7 +1494,6 @@ int journal_flush(journal_t *journal)
{
int err = 0;
transaction_t *transaction = NULL;
- unsigned int old_tail;
spin_lock(&journal->j_state_lock);
@@ -1499,14 +1535,8 @@ int 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. */
+ mark_journal_empty(journal);
spin_lock(&journal->j_state_lock);
- old_tail = journal->j_tail;
- journal->j_tail = 0;
- spin_unlock(&journal->j_state_lock);
- journal_update_superblock(journal, 1);
- spin_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);
@@ -1547,7 +1577,7 @@ int journal_wipe(journal_t *journal, int write)
err = journal_skip_recovery(journal);
if (write)
- journal_update_superblock(journal, 1);
+ mark_journal_empty(journal);
no_recovery:
return err;
@@ -1615,7 +1645,7 @@ static void __journal_abort_soft (journal_t *journal, int errno)
__journal_abort_hard(journal);
if (errno)
- journal_update_superblock(journal, 1);
+ journal_update_sb_errno(journal);
}
/**
diff --git a/include/linux/jbd.h b/include/linux/jbd.h
index f265682..9716d37 100644
--- a/include/linux/jbd.h
+++ b/include/linux/jbd.h
@@ -864,7 +864,7 @@ extern int journal_destroy (journal_t *);
extern int journal_recover (journal_t *journal);
extern int journal_wipe (journal_t *, int);
extern int journal_skip_recovery (journal_t *);
-extern void journal_update_superblock (journal_t *, int);
+extern void journal_update_sb_log_tail (journal_t *);
extern void journal_abort (journal_t *, int);
extern int journal_errno (journal_t *);
extern void journal_ack_err (journal_t *);
diff --git a/include/trace/events/jbd.h b/include/trace/events/jbd.h
index 9305e1b..d9658a9 100644
--- a/include/trace/events/jbd.h
+++ b/include/trace/events/jbd.h
@@ -169,24 +169,20 @@ TRACE_EVENT(jbd_cleanup_journal_tail,
__entry->block_nr, __entry->freed)
);
-TRACE_EVENT(jbd_update_superblock_end,
- TP_PROTO(journal_t *journal, int wait),
+TRACE_EVENT(journal_write_superblock,
+ 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_JBD_H */
--
1.7.1
--
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