[PATCH 5/7] writeback: inline allocation failure handling in bdi_alloc_queue_work()

Jens Axboe
2009-09-14T09:37:06Z

This gets rid of work == NULL in bdi_queue_work() and puts the
OOM handling where it belongs.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
---
fs/fs-writeback.c | 55 +++++++++++++++++++++++++++-------------------------
1 files changed, 29 insertions(+), 26 deletions(-)

diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index d7592c7..5cd8b3b 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -139,21 +139,19 @@ static void wb_clear_pending(struct bdi_writeback *wb, struct bdi_work *work)

static void bdi_queue_work(struct backing_dev_info *bdi, struct bdi_work *work)
{
- if (work) {
- work->seen = bdi->wb_mask;
- BUG_ON(!work->seen);
- atomic_set(&work->pending, bdi->wb_cnt);
- BUG_ON(!bdi->wb_cnt);
+ work->seen = bdi->wb_mask;
+ BUG_ON(!work->seen);
+ atomic_set(&work->pending, bdi->wb_cnt);
+ BUG_ON(!bdi->wb_cnt);

- /*
- * Make sure stores are seen before it appears on the list
- */
- smp_mb();
+ /*
+ * Make sure stores are seen before it appears on the list
+ */
+ smp_mb();

- spin_lock(&bdi->wb_lock);
- list_add_tail_rcu(&work->list, &bdi->work_list);
- spin_unlock(&bdi->wb_lock);
- }
+ spin_lock(&bdi->wb_lock);
+ list_add_tail_rcu(&work->list, &bdi->work_list);
+ spin_unlock(&bdi->wb_lock);

/*
* If the default thread isn't there, make sure we add it. When
@@ -165,14 +163,12 @@ static void bdi_queue_work(struct backing_dev_info *bdi, struct bdi_work *work)
struct bdi_writeback *wb = &bdi->wb;

/*
- * If we failed allocating the bdi work item, wake up the wb
- * thread always. As a safety precaution, it'll flush out
- * everything
+ * End work now if this wb has no dirty IO pending. Otherwise
+ * wakeup the handling thread
*/
- if (!wb_has_dirty_io(wb)) {
- if (work)
- wb_clear_pending(wb, work);
- } else if (wb->task)
+ if (!wb_has_dirty_io(wb))
+ wb_clear_pending(wb, work);
+ else if (wb->task)
wake_up_process(wb->task);
}
}
@@ -192,11 +188,20 @@ static void bdi_alloc_queue_work(struct backing_dev_info *bdi,
{
struct bdi_work *work;

+ /*
+ * This is WB_SYNC_NONE writeback, so if allocation fails just
+ * wakeup the thread for old dirty data writeback
+ */
work = kmalloc(sizeof(*work), GFP_ATOMIC);
- if (work)
+ if (work) {
bdi_work_init(work, wbc);
+ bdi_queue_work(bdi, work);
+ } else {
+ struct bdi_writeback *wb = &bdi->wb;

- bdi_queue_work(bdi, work);
+ if (wb->task)
+ wake_up_process(wb->task);
+ }
}

void bdi_start_writeback(struct writeback_control *wbc)
@@ -852,10 +857,8 @@ static void bdi_writeback_all(struct writeback_control *wbc)
rcu_read_lock();

list_for_each_entry(bdi, &bdi_list, bdi_list) {
- if (!bdi_has_dirty_io(bdi))
- continue;
-
- bdi_alloc_queue_work(bdi, wbc);
+ if (bdi_has_dirty_io(bdi))
+ bdi_alloc_queue_work(bdi, wbc);
}

rcu_read_unlock();
--
1.6.4.1.207.g68ea