Commit 5cb738b5 authored by Andreas Gruenbacher's avatar Andreas Gruenbacher
Browse files

gfs2: Get rid of current_tail() 



Keep the current value of the updated log tail in the super block as
sb_log_flush_tail instead of computing it on the fly.  This avoids
unnecessary sd_ail_lock taking and cleans up the code.

Signed-off-by: default avatarAndreas Gruenbacher <agruenba@redhat.com>
parent 297de318

fs/gfs2/incore.h

+3 −2
Original line number Diff line number Diff line
@@ -838,8 +838,6 @@ struct gfs2_sbd { 
	wait_queue_head_t sd_logd_waitq;



	u64 sd_log_sequence;

	unsigned int sd_log_head;

	unsigned int sd_log_tail;

	int sd_log_idle;



	struct rw_semaphore sd_log_flush_lock;
@@ -849,6 +847,9 @@ struct gfs2_sbd { 
	int sd_log_error; /* First log error */

	wait_queue_head_t sd_withdraw_wait;



	unsigned int sd_log_tail;

	unsigned int sd_log_flush_tail;

	unsigned int sd_log_head;

	unsigned int sd_log_flush_head;



	spinlock_t sd_ail_lock;

fs/gfs2/log.c

+38 −34
Original line number Diff line number Diff line
@@ -242,6 +242,28 @@ static void gfs2_ail1_start(struct gfs2_sbd *sdp) 
	return gfs2_ail1_flush(sdp, &wbc);

}



static void gfs2_log_update_flush_tail(struct gfs2_sbd *sdp)

{

	unsigned int new_flush_tail = sdp->sd_log_head;

	struct gfs2_trans *tr;



	if (!list_empty(&sdp->sd_ail1_list)) {

		tr = list_last_entry(&sdp->sd_ail1_list,

				     struct gfs2_trans, tr_list);

		new_flush_tail = tr->tr_first;

	}

	sdp->sd_log_flush_tail = new_flush_tail;

}



static void gfs2_log_update_head(struct gfs2_sbd *sdp)

{

	unsigned int new_head = sdp->sd_log_flush_head;



	if (sdp->sd_log_flush_tail == sdp->sd_log_head)

		sdp->sd_log_flush_tail = new_head;

	sdp->sd_log_head = new_head;

}



/**

 * gfs2_ail1_empty_one - Check whether or not a trans in the AIL has been synced

 * @sdp: the filesystem
@@ -317,6 +339,7 @@ static int gfs2_ail1_empty(struct gfs2_sbd *sdp, int max_revokes) 
		else

			oldest_tr = 0;

	}

	gfs2_log_update_flush_tail(sdp);

	ret = list_empty(&sdp->sd_ail1_list);

	spin_unlock(&sdp->sd_ail_lock);
@@ -544,30 +567,14 @@ static unsigned int calc_reserved(struct gfs2_sbd *sdp) 
	return reserved;

}



static unsigned int current_tail(struct gfs2_sbd *sdp)

static void log_pull_tail(struct gfs2_sbd *sdp)

{

	struct gfs2_trans *tr;

	unsigned int tail;



	spin_lock(&sdp->sd_ail_lock);



	if (list_empty(&sdp->sd_ail1_list)) {

		tail = sdp->sd_log_head;

	} else {

		tr = list_last_entry(&sdp->sd_ail1_list, struct gfs2_trans,

				tr_list);

		tail = tr->tr_first;

	}



	spin_unlock(&sdp->sd_ail_lock);



	return tail;

}



static void log_pull_tail(struct gfs2_sbd *sdp, unsigned int new_tail)

{

	unsigned int dist = log_distance(sdp, new_tail, sdp->sd_log_tail);

	unsigned int new_tail = sdp->sd_log_flush_tail;

	unsigned int dist;



	if (new_tail == sdp->sd_log_tail)

		return;

	dist = log_distance(sdp, new_tail, sdp->sd_log_tail);

	ail2_empty(sdp, new_tail);

	gfs2_log_release(sdp, dist);

	sdp->sd_log_tail = new_tail;
@@ -822,26 +829,23 @@ void gfs2_write_log_header(struct gfs2_sbd *sdp, struct gfs2_jdesc *jd, 


static void log_write_header(struct gfs2_sbd *sdp, u32 flags)

{

	unsigned int tail;

	int op_flags = REQ_PREFLUSH | REQ_FUA | REQ_META | REQ_SYNC;

	enum gfs2_freeze_state state = atomic_read(&sdp->sd_freeze_state);



	gfs2_assert_withdraw(sdp, (state != SFS_FROZEN));

	tail = current_tail(sdp);



	if (test_bit(SDF_NOBARRIERS, &sdp->sd_flags)) {

		gfs2_ordered_wait(sdp);

		log_flush_wait(sdp);

		op_flags = REQ_SYNC | REQ_META | REQ_PRIO;

	}

	sdp->sd_log_idle = (tail == sdp->sd_log_flush_head);

	gfs2_write_log_header(sdp, sdp->sd_jdesc, sdp->sd_log_sequence++, tail,

			      sdp->sd_log_flush_head, flags, op_flags);

	sdp->sd_log_idle = (sdp->sd_log_flush_tail == sdp->sd_log_flush_head);

	gfs2_write_log_header(sdp, sdp->sd_jdesc, sdp->sd_log_sequence++,

			      sdp->sd_log_flush_tail, sdp->sd_log_flush_head,

			      flags, op_flags);

	gfs2_log_incr_head(sdp);

	log_flush_wait(sdp);



	if (sdp->sd_log_tail != tail)

		log_pull_tail(sdp, tail);

	log_pull_tail(sdp);

}



/**
@@ -991,7 +995,7 @@ void gfs2_log_flush(struct gfs2_sbd *sdp, struct gfs2_glock *gl, u32 flags) 
	if (sdp->sd_log_head != sdp->sd_log_flush_head) {

		log_flush_wait(sdp);

		log_write_header(sdp, flags);

	} else if (sdp->sd_log_tail != current_tail(sdp) && !sdp->sd_log_idle) {

	} else if (sdp->sd_log_tail != sdp->sd_log_flush_tail && !sdp->sd_log_idle) {

		atomic_dec(&sdp->sd_log_blks_free); /* Adjust for unreserved buffer */

		trace_gfs2_log_blocks(sdp, -1);

		log_write_header(sdp, flags);
@@ -1001,7 +1005,7 @@ void gfs2_log_flush(struct gfs2_sbd *sdp, struct gfs2_glock *gl, u32 flags) 
	lops_after_commit(sdp, tr);



	gfs2_log_lock(sdp);

	sdp->sd_log_head = sdp->sd_log_flush_head;

	gfs2_log_update_head(sdp);

	sdp->sd_log_blks_reserved = 0;

	sdp->sd_log_committed_revoke = 0;
@@ -1021,7 +1025,7 @@ void gfs2_log_flush(struct gfs2_sbd *sdp, struct gfs2_glock *gl, u32 flags) 
			atomic_dec(&sdp->sd_log_blks_free); /* Adjust for unreserved buffer */

			trace_gfs2_log_blocks(sdp, -1);

			log_write_header(sdp, flags);

			sdp->sd_log_head = sdp->sd_log_flush_head;

			gfs2_log_update_head(sdp);

		}

		if (flags & (GFS2_LOG_HEAD_FLUSH_SHUTDOWN |

			     GFS2_LOG_HEAD_FLUSH_FREEZE))
@@ -1156,7 +1160,7 @@ static void gfs2_log_shutdown(struct gfs2_sbd *sdp) 
	gfs2_assert_warn(sdp, sdp->sd_log_head == sdp->sd_log_tail);

	gfs2_assert_warn(sdp, list_empty(&sdp->sd_ail2_list));



	sdp->sd_log_head = sdp->sd_log_flush_head;

	gfs2_log_update_head(sdp);

	sdp->sd_log_tail = sdp->sd_log_head;

}

fs/gfs2/log.h

+3 −1
Original line number Diff line number Diff line
@@ -43,7 +43,9 @@ static inline void gfs2_log_pointers_init(struct gfs2_sbd *sdp, 
	if (++value == sdp->sd_jdesc->jd_blocks) {

		value = 0;

	}

	sdp->sd_log_head = sdp->sd_log_tail = value;

	sdp->sd_log_tail = value;

	sdp->sd_log_flush_tail = value;

	sdp->sd_log_head = value;

}



static inline void gfs2_ordered_add_inode(struct gfs2_inode *ip)