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Commit 1a0d3786 authored by Theodore Ts'o's avatar Theodore Ts'o
Browse files

jbd2: Remove a large array of bh's from the stack of the checkpoint routine 



jbd2_log_do_checkpoint()n is one of the kernel's largest stack users.
Move the array of buffer head's from the stack of jbd2_log_do_checkpoint()
to the in-core journal structure.

Signed-off-by: default avatar"Theodore Ts'o" <tytso@mit.edu>
parent 498e5f24

fs/jbd2/checkpoint.c

+9 −13
Original line number Diff line number Diff line
@@ -249,16 +249,14 @@ static int __wait_cp_io(journal_t *journal, transaction_t *transaction) 
	return ret;

}



#define NR_BATCH	64



static void

__flush_batch(journal_t *journal, struct buffer_head **bhs, int *batch_count)

__flush_batch(journal_t *journal, int *batch_count)

{

	int i;



	ll_rw_block(SWRITE, *batch_count, bhs);

	ll_rw_block(SWRITE, *batch_count, journal->j_chkpt_bhs);

	for (i = 0; i < *batch_count; i++) {

		struct buffer_head *bh = bhs[i];

		struct buffer_head *bh = journal->j_chkpt_bhs[i];

		clear_buffer_jwrite(bh);

		BUFFER_TRACE(bh, "brelse");

		__brelse(bh);
@@ -277,8 +275,7 @@ __flush_batch(journal_t *journal, struct buffer_head **bhs, int *batch_count) 
 * Called under jbd_lock_bh_state(jh2bh(jh)), and drops it

 */

static int __process_buffer(journal_t *journal, struct journal_head *jh,

			struct buffer_head **bhs, int *batch_count,

			transaction_t *transaction)

			    int *batch_count, transaction_t *transaction)

{

	struct buffer_head *bh = jh2bh(jh);

	int ret = 0;
@@ -325,14 +322,14 @@ static int __process_buffer(journal_t *journal, struct journal_head *jh, 
		get_bh(bh);

		J_ASSERT_BH(bh, !buffer_jwrite(bh));

		set_buffer_jwrite(bh);

		bhs[*batch_count] = bh;

		journal->j_chkpt_bhs[*batch_count] = bh;

		__buffer_relink_io(jh);

		jbd_unlock_bh_state(bh);

		transaction->t_chp_stats.cs_written++;

		(*batch_count)++;

		if (*batch_count == NR_BATCH) {

		if (*batch_count == JBD2_NR_BATCH) {

			spin_unlock(&journal->j_list_lock);

			__flush_batch(journal, bhs, batch_count);

			__flush_batch(journal, batch_count);

			ret = 1;

		}

	}
@@ -388,7 +385,6 @@ int jbd2_log_do_checkpoint(journal_t *journal) 
	if (journal->j_checkpoint_transactions == transaction &&

			transaction->t_tid == this_tid) {

		int batch_count = 0;

		struct buffer_head *bhs[NR_BATCH];

		struct journal_head *jh;

		int retry = 0, err;
@@ -402,7 +398,7 @@ int jbd2_log_do_checkpoint(journal_t *journal) 
				retry = 1;

				break;

			}

			retry = __process_buffer(journal, jh, bhs, &batch_count,

			retry = __process_buffer(journal, jh, &batch_count,

						 transaction);

			if (retry < 0 && !result)

				result = retry;
@@ -419,7 +415,7 @@ int jbd2_log_do_checkpoint(journal_t *journal) 
				spin_unlock(&journal->j_list_lock);

				retry = 1;

			}

			__flush_batch(journal, bhs, &batch_count);

			__flush_batch(journal, &batch_count);

		}



		if (retry) {

fs/jbd2/journal.c

+2 −0
Original line number Diff line number Diff line
@@ -1477,7 +1477,9 @@ int jbd2_journal_destroy(journal_t *journal) 
	spin_lock(&journal->j_list_lock);

	while (journal->j_checkpoint_transactions != NULL) {

		spin_unlock(&journal->j_list_lock);

		mutex_lock(&journal->j_checkpoint_mutex);

		jbd2_log_do_checkpoint(journal);

		mutex_unlock(&journal->j_checkpoint_mutex);

		spin_lock(&journal->j_list_lock);

	}

include/linux/jbd2.h

+10 −0
Original line number Diff line number Diff line
@@ -687,6 +687,8 @@ jbd2_time_diff(unsigned long start, unsigned long end) 
	return end + (MAX_JIFFY_OFFSET - start);

}



#define JBD2_NR_BATCH	64



/**

 * struct journal_s - The journal_s type is the concrete type associated with

 *     journal_t.
@@ -830,6 +832,14 @@ struct journal_s 
	/* Semaphore for locking against concurrent checkpoints */

	struct mutex		j_checkpoint_mutex;



	/*

	 * List of buffer heads used by the checkpoint routine.  This

	 * was moved from jbd2_log_do_checkpoint() to reduce stack

	 * usage.  Access to this array is controlled by the

	 * j_checkpoint_mutex.  [j_checkpoint_mutex]

	 */

	struct buffer_head	*j_chkpt_bhs[JBD2_NR_BATCH];

	

	/*

	 * Journal head: identifies the first unused block in the journal.

	 * [j_state_lock]