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jbd2: split updating of journal superblock and marking journal empty

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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@suse.cz>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
This commit is contained in:
Jan Kara 2012-03-13 15:41:04 -04:00 committed by Theodore Ts'o
parent 31d4f3a2f3
commit 24bcc89c7e
5 changed files with 106 additions and 83 deletions
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2
fs/jbd2/checkpoint.c
View File

@ -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;
}

2
fs/jbd2/commit.c
View File

@ -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");
}

171
fs/jbd2/journal.c
View File

@ -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
@ -1160,49 +1150,98 @@ void jbd2_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)) {
printk(KERN_ERR "JBD2: I/O error detected "
"when updating journal superblock for %s.\n",
journal->j_devname);
clear_buffer_write_io_error(bh);
set_buffer_uptodate(bh);
}
}
/**
* 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;
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);
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);
WARN_ON(!sb->s_sequence);
journal->j_flags &= ~JBD2_FLUSHED;
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);
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 "
"when updating journal superblock for %s.\n",
journal->j_devname);
clear_buffer_write_io_error(bh);
set_buffer_uptodate(bh);
}
} else
write_dirty_buffer(bh, WRITE);
trace_jbd2_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. */
write_lock(&journal->j_state_lock);
if (sb->s_start)
journal->j_flags &= ~JBD2_FLUSHED;
else
journal->j_flags |= JBD2_FLUSHED;
write_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);
}
/**

2
include/linux/jbd2.h
View File

@ -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 *);

12
include/trace/events/jbd2.h
View File

@ -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 */