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jbd2: Add function jbd2_trans_will_send_data_barrier()

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Provide a function which returns whether a transaction with given tid
will send a flush to the filesystem device.  The function will be used
by ext4 to detect whether fsync needs to send a separate flush or not.

Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
This commit is contained in:
Jan Kara
2011-05-24 11:59:18 -04:00
committed by Theodore Ts'o
parent 81be12c817
commit bbd2be3691
3 changed files with 53 additions and 2 deletions
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41
fs/jbd2/journal.c
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@@ -587,6 +587,47 @@ int jbd2_journal_start_commit(journal_t *journal, tid_t *ptid)
return ret;
}
/*
* Return 1 if a given transaction has not yet sent barrier request
* connected with a transaction commit. If 0 is returned, transaction
* may or may not have sent the barrier. Used to avoid sending barrier
* twice in common cases.
*/
int jbd2_trans_will_send_data_barrier(journal_t *journal, tid_t tid)
{
int ret = 0;
transaction_t *commit_trans;
if (!(journal->j_flags & JBD2_BARRIER))
return 0;
read_lock(&journal->j_state_lock);
/* Transaction already committed? */
if (tid_geq(journal->j_commit_sequence, tid))
goto out;
commit_trans = journal->j_committing_transaction;
if (!commit_trans || commit_trans->t_tid != tid) {
ret = 1;
goto out;
}
/*
* Transaction is being committed and we already proceeded to
* submitting a flush to fs partition?
*/
if (journal->j_fs_dev != journal->j_dev) {
if (!commit_trans->t_need_data_flush ||
commit_trans->t_state >= T_COMMIT_DFLUSH)
goto out;
} else {
if (commit_trans->t_state >= T_COMMIT_JFLUSH)
goto out;
}
ret = 1;
out:
read_unlock(&journal->j_state_lock);
return ret;
}
EXPORT_SYMBOL(jbd2_trans_will_send_data_barrier);
/*
* Wait for a specified commit to complete.
* The caller may not hold the journal lock.