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-rw-r--r--fs/jbd2/commit.c32
-rw-r--r--fs/jbd2/journal.c13
2 files changed, 45 insertions, 0 deletions
diff --git a/fs/jbd2/commit.c b/fs/jbd2/commit.c
index b89ef84786a7..1dfcb207ea69 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
@@ -688,10 +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
@@ -842,6 +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
diff --git a/fs/jbd2/journal.c b/fs/jbd2/journal.c
index c5ff177400ff..bda564f63864 100644
--- a/fs/jbd2/journal.c
+++ b/fs/jbd2/journal.c
@@ -821,6 +821,19 @@ void __jbd2_update_log_tail(journal_t *journal, tid_t tid, unsigned long block)
write_unlock(&journal->j_state_lock);
}
+/*
+ * This is a variaon of __jbd2_update_log_tail which checks for validity of
+ * provided log tail and locks j_checkpoint_mutex. So it is safe against races
+ * with other threads updating log tail.
+ */
+void jbd2_update_log_tail(journal_t *journal, tid_t tid, unsigned long block)
+{
+ mutex_lock(&journal->j_checkpoint_mutex);
+ if (tid_gt(tid, journal->j_tail_sequence))
+ __jbd2_update_log_tail(journal, tid, block);
+ mutex_unlock(&journal->j_checkpoint_mutex);
+}
+
struct jbd2_stats_proc_session {
journal_t *journal;
struct transaction_stats_s *stats;