Commit f11fcae8 authored by Jens Axboe's avatar Jens Axboe
Browse files

writeback: only use bdi_writeback_all() for WB_SYNC_NONE writeout 



Data integrity writeback must use bdi_start_writeback() and ensure
that wbc->sb and wbc->bdi are set.

Acked-by: default avatarJan Kara <jack@suse.cz>
Signed-off-by: default avatarJens Axboe <jens.axboe@oracle.com>
parent 32a88aa1

fs/fs-writeback.c

+14 −56
Original line number Diff line number Diff line
@@ -50,7 +50,6 @@ struct wb_writeback_args { 
 */

struct bdi_work {

	struct list_head list;

	struct list_head wait_list;

	struct rcu_head rcu_head;



	unsigned long seen;
@@ -198,7 +197,8 @@ static void bdi_wait_on_work_clear(struct bdi_work *work) 
		    TASK_UNINTERRUPTIBLE);

}



static struct bdi_work *bdi_alloc_work(struct writeback_control *wbc)

static void bdi_alloc_queue_work(struct backing_dev_info *bdi,

				 struct writeback_control *wbc)

{

	struct bdi_work *work;
@@ -206,7 +206,7 @@ static struct bdi_work *bdi_alloc_work(struct writeback_control *wbc) 
	if (work)

		bdi_work_init(work, wbc);



	return work;

	bdi_queue_work(bdi, work);

}



void bdi_start_writeback(struct writeback_control *wbc)
@@ -216,11 +216,9 @@ void bdi_start_writeback(struct writeback_control *wbc) 
	 * bdi_queue_work() will wake up the thread and flush old data. This

	 * should ensure some amount of progress in freeing memory.

	 */

	if (wbc->sync_mode != WB_SYNC_ALL) {

		struct bdi_work *w = bdi_alloc_work(wbc);



		bdi_queue_work(wbc->bdi, w);

	} else {

	if (wbc->sync_mode != WB_SYNC_ALL)

		bdi_alloc_queue_work(wbc->bdi, wbc);

	else {

		struct bdi_work work;



		bdi_work_init(&work, wbc);
@@ -860,67 +858,26 @@ int bdi_writeback_task(struct bdi_writeback *wb) 
}



/*

 * Schedule writeback for all backing devices. Expensive! If this is a data

 * integrity operation, writeback will be complete when this returns. If

 * we are simply called for WB_SYNC_NONE, then writeback will merely be

 * scheduled to run.

 * Schedule writeback for all backing devices. Can only be used for

 * WB_SYNC_NONE writeback, WB_SYNC_ALL should use bdi_start_writeback()

 * and pass in the superblock.

 */

static void bdi_writeback_all(struct writeback_control *wbc)

{

	const bool must_wait = wbc->sync_mode == WB_SYNC_ALL;

	struct backing_dev_info *bdi;

	struct bdi_work *work;

	LIST_HEAD(list);



restart:

	WARN_ON(wbc->sync_mode == WB_SYNC_ALL);



	spin_lock(&bdi_lock);



	list_for_each_entry(bdi, &bdi_list, bdi_list) {

		struct bdi_work *work;



		if (!bdi_has_dirty_io(bdi))

			continue;



		/*

		 * If work allocation fails, do the writes inline. We drop

		 * the lock and restart the list writeout. This should be OK,

		 * since this happens rarely and because the writeout should

		 * eventually make more free memory available.

		 */

		work = bdi_alloc_work(wbc);

		if (!work) {

			struct writeback_control __wbc;



			/*

			 * Not a data integrity writeout, just continue

			 */

			if (!must_wait)

				continue;



			spin_unlock(&bdi_lock);

			__wbc = *wbc;

			__wbc.bdi = bdi;

			writeback_inodes_wbc(&__wbc);

			goto restart;

		}

		if (must_wait)

			list_add_tail(&work->wait_list, &list);



		bdi_queue_work(bdi, work);

		bdi_alloc_queue_work(bdi, wbc);

	}



	spin_unlock(&bdi_lock);



	/*

	 * If this is for WB_SYNC_ALL, wait for pending work to complete

	 * before returning.

	 */

	while (!list_empty(&list)) {

		work = list_entry(list.next, struct bdi_work, wait_list);

		list_del(&work->wait_list);

		bdi_wait_on_work_clear(work);

		call_rcu(&work->rcu_head, bdi_work_free);

	}

}



/*
@@ -1177,6 +1134,7 @@ long sync_inodes_sb(struct super_block *sb) 
{

	struct writeback_control wbc = {

		.sb		= sb,

		.bdi		= sb->s_bdi,

		.sync_mode	= WB_SYNC_ALL,

		.range_start	= 0,

		.range_end	= LLONG_MAX,
@@ -1184,7 +1142,7 @@ long sync_inodes_sb(struct super_block *sb) 
	long nr_to_write = LONG_MAX; /* doesn't actually matter */



	wbc.nr_to_write = nr_to_write;

	bdi_writeback_all(&wbc);

	bdi_start_writeback(&wbc);

	wait_sb_inodes(&wbc);

	return nr_to_write - wbc.nr_to_write;

}