Commit 484adff8 authored by Steven Whitehouse's avatar Steven Whitehouse
Browse files

[GFS2] Update locking in log.c 



Replace the lock_for_trans()/lock_for_flush() functions with an rwsem.
In fact the sd_log_flush_lock becomes an rwsem (the write part of it)
and is extended slightly to cover everything that the lock_for_flush()
used to cover. The read part of the lock is instead of lock_for_trans().

This corrects the races in the original code and reduces the code size.

Signed-off-by: default avatarSteven Whitehouse <swhiteho@redhat.com>
parent 7aabffca

fs/gfs2/incore.h

+1 −5
Original line number Diff line number Diff line
@@ -611,10 +611,6 @@ struct gfs2_sbd { 
	/* Log stuff */



	spinlock_t sd_log_lock;

	atomic_t sd_log_trans_count;

	wait_queue_head_t sd_log_trans_wq;

	atomic_t sd_log_flush_count;

	wait_queue_head_t sd_log_flush_wq;



	unsigned int sd_log_blks_reserved;

	unsigned int sd_log_commited_buf;
@@ -643,7 +639,7 @@ struct gfs2_sbd { 
	int sd_log_idle;



	unsigned long sd_log_flush_time;

	struct mutex sd_log_flush_lock;

	struct rw_semaphore sd_log_flush_lock;

	struct list_head sd_log_flush_list;



	unsigned int sd_log_flush_head;

fs/gfs2/log.c

+18 −49
Original line number Diff line number Diff line
@@ -29,32 +29,6 @@ 


#define PULL 1



static void lock_for_trans(struct gfs2_sbd *sdp)

{

	wait_event(sdp->sd_log_trans_wq, atomic_read(&sdp->sd_log_flush_count) ? 0 : 1);

	atomic_inc(&sdp->sd_log_trans_count);

}



static void unlock_from_trans(struct gfs2_sbd *sdp)

{

	gfs2_assert_warn(sdp, atomic_read(&sdp->sd_log_trans_count));

	if (atomic_dec_and_test(&sdp->sd_log_trans_count))

		wake_up(&sdp->sd_log_flush_wq);

}



static void gfs2_lock_for_flush(struct gfs2_sbd *sdp)

{

	atomic_inc(&sdp->sd_log_flush_count);

	wait_event(sdp->sd_log_flush_wq, atomic_read(&sdp->sd_log_trans_count) ? 0 : 1);

}



static void gfs2_unlock_from_flush(struct gfs2_sbd *sdp)

{

	gfs2_assert_warn(sdp, atomic_read(&sdp->sd_log_flush_count));

	if (atomic_dec_and_test(&sdp->sd_log_flush_count))

		wake_up(&sdp->sd_log_trans_wq);

}



/**

 * gfs2_struct2blk - compute stuff

 * @sdp: the filesystem
@@ -109,8 +83,7 @@ void gfs2_ail1_start(struct gfs2_sbd *sdp, int flags) 
		first = NULL;



	for (;;) {

		if (first &&

		    (head->prev != first ||

		if (first && (head->prev != first ||

			      gfs2_ail1_empty_one(sdp, first_ai, 0)))

			break;
@@ -194,23 +167,21 @@ int gfs2_log_reserve(struct gfs2_sbd *sdp, unsigned int blks) 
		return -EINVAL;



	mutex_lock(&sdp->sd_log_reserve_mutex);

	for (;;) {

	gfs2_log_lock(sdp);

		if (sdp->sd_log_blks_free > blks) {

			sdp->sd_log_blks_free -= blks;

			gfs2_log_unlock(sdp);

			mutex_unlock(&sdp->sd_log_reserve_mutex);

			break;

		}



	while(sdp->sd_log_blks_free <= blks) {

		gfs2_log_unlock(sdp);

		gfs2_ail1_empty(sdp, 0);

		gfs2_log_flush(sdp);



		if (try++)

			gfs2_ail1_start(sdp, 0);

		gfs2_log_lock(sdp);

	}

	lock_for_trans(sdp);

	sdp->sd_log_blks_free -= blks;

	gfs2_log_unlock(sdp);

	mutex_unlock(&sdp->sd_log_reserve_mutex);



	down_read(&sdp->sd_log_flush_lock);



	return 0;

}
@@ -224,7 +195,7 @@ int gfs2_log_reserve(struct gfs2_sbd *sdp, unsigned int blks) 


void gfs2_log_release(struct gfs2_sbd *sdp, unsigned int blks)

{

	unlock_from_trans(sdp);

	up_read(&sdp->sd_log_flush_lock);



	gfs2_log_lock(sdp);

	sdp->sd_log_blks_free += blks;
@@ -474,20 +445,20 @@ void gfs2_log_flush_i(struct gfs2_sbd *sdp, struct gfs2_glock *gl) 
	ai = kzalloc(sizeof(struct gfs2_ail), GFP_NOFS | __GFP_NOFAIL);

	INIT_LIST_HEAD(&ai->ai_ail1_list);

	INIT_LIST_HEAD(&ai->ai_ail2_list);

	gfs2_lock_for_flush(sdp);



	down_write(&sdp->sd_log_flush_lock);



	if (gl) {

		gfs2_log_lock(sdp);

		if (list_empty(&gl->gl_le.le_list)) {

			gfs2_log_unlock(sdp);

			gfs2_unlock_from_flush(sdp);

			up_write(&sdp->sd_log_flush_lock);

			kfree(ai);

			return;

		}

		gfs2_log_unlock(sdp);

	}



	mutex_lock(&sdp->sd_log_flush_lock);



	gfs2_assert_withdraw(sdp,

			sdp->sd_log_num_buf == sdp->sd_log_commited_buf);
@@ -519,9 +490,8 @@ void gfs2_log_flush_i(struct gfs2_sbd *sdp, struct gfs2_glock *gl) 
	}

	gfs2_log_unlock(sdp);



	mutex_unlock(&sdp->sd_log_flush_lock);

	sdp->sd_vfs->s_dirt = 0;

	gfs2_unlock_from_flush(sdp);

	up_write(&sdp->sd_log_flush_lock);



	kfree(ai);

}
@@ -573,7 +543,7 @@ void gfs2_log_commit(struct gfs2_sbd *sdp, struct gfs2_trans *tr) 
	lops_incore_commit(sdp, tr);



	sdp->sd_vfs->s_dirt = 1;

	unlock_from_trans(sdp);

	up_read(&sdp->sd_log_flush_lock);



	gfs2_log_lock(sdp);

	if (sdp->sd_log_num_buf > gfs2_tune_get(sdp, gt_incore_log_blocks)) {
@@ -591,9 +561,8 @@ void gfs2_log_commit(struct gfs2_sbd *sdp, struct gfs2_trans *tr) 


void gfs2_log_shutdown(struct gfs2_sbd *sdp)

{

	mutex_lock(&sdp->sd_log_flush_lock);

	down_write(&sdp->sd_log_flush_lock);



	gfs2_assert_withdraw(sdp, !atomic_read(&sdp->sd_log_trans_count));

	gfs2_assert_withdraw(sdp, !sdp->sd_log_blks_reserved);

	gfs2_assert_withdraw(sdp, !sdp->sd_log_num_gl);

	gfs2_assert_withdraw(sdp, !sdp->sd_log_num_buf);
@@ -618,6 +587,6 @@ void gfs2_log_shutdown(struct gfs2_sbd *sdp) 
		sdp->sd_log_wraps++;

	sdp->sd_log_tail = sdp->sd_log_head;



	mutex_unlock(&sdp->sd_log_flush_lock);

	up_write(&sdp->sd_log_flush_lock);

}

fs/gfs2/ops_fstype.c

+1 −3
Original line number Diff line number Diff line
@@ -88,8 +88,6 @@ static struct gfs2_sbd *init_sbd(struct super_block *sb) 
	mutex_init(&sdp->sd_quota_mutex);



	spin_lock_init(&sdp->sd_log_lock);

	init_waitqueue_head(&sdp->sd_log_trans_wq);

	init_waitqueue_head(&sdp->sd_log_flush_wq);



	INIT_LIST_HEAD(&sdp->sd_log_le_gl);

	INIT_LIST_HEAD(&sdp->sd_log_le_buf);
@@ -101,7 +99,7 @@ static struct gfs2_sbd *init_sbd(struct super_block *sb) 
	INIT_LIST_HEAD(&sdp->sd_ail1_list);

	INIT_LIST_HEAD(&sdp->sd_ail2_list);



	mutex_init(&sdp->sd_log_flush_lock);

	init_rwsem(&sdp->sd_log_flush_lock);

	INIT_LIST_HEAD(&sdp->sd_log_flush_list);



	INIT_LIST_HEAD(&sdp->sd_revoke_list);

fs/gfs2/trans.c

+2 −2

File changed.

Contains only whitespace changes.