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-rw-r--r--fs/fs-writeback.c47
1 files changed, 45 insertions, 2 deletions
diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index d7d4a1bcdd2f..093b9594e846 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -52,6 +52,8 @@ struct wb_writeback_work {
unsigned int for_background:1;
unsigned int for_sync:1; /* sync(2) WB_SYNC_ALL writeback */
unsigned int auto_free:1; /* free on completion */
+ unsigned int single_wait:1;
+ unsigned int single_done:1;
enum wb_reason reason; /* why was writeback initiated? */
struct list_head list; /* pending work list */
@@ -178,8 +180,11 @@ static void wb_queue_work(struct bdi_writeback *wb,
trace_writeback_queue(wb->bdi, work);
spin_lock_bh(&wb->work_lock);
- if (!test_bit(WB_registered, &wb->state))
+ if (!test_bit(WB_registered, &wb->state)) {
+ if (work->single_wait)
+ work->single_done = 1;
goto out_unlock;
+ }
if (work->done)
atomic_inc(&work->done->cnt);
list_add_tail(&work->list, &wb->work_list);
@@ -234,6 +239,32 @@ int inode_congested(struct inode *inode, int cong_bits)
EXPORT_SYMBOL_GPL(inode_congested);
/**
+ * wb_wait_for_single_work - wait for completion of a single bdi_writeback_work
+ * @bdi: bdi the work item was issued to
+ * @work: work item to wait for
+ *
+ * Wait for the completion of @work which was issued to one of @bdi's
+ * bdi_writeback's. The caller must have set @work->single_wait before
+ * issuing it. This wait operates independently fo
+ * wb_wait_for_completion() and also disables automatic freeing of @work.
+ */
+static void wb_wait_for_single_work(struct backing_dev_info *bdi,
+ struct wb_writeback_work *work)
+{
+ if (WARN_ON_ONCE(!work->single_wait))
+ return;
+
+ wait_event(bdi->wb_waitq, work->single_done);
+
+ /*
+ * Paired with smp_wmb() in wb_do_writeback() and ensures that all
+ * modifications to @work prior to assertion of ->single_done is
+ * visible to the caller once this function returns.
+ */
+ smp_rmb();
+}
+
+/**
* wb_split_bdi_pages - split nr_pages to write according to bandwidth
* @wb: target bdi_writeback to split @nr_pages to
* @nr_pages: number of pages to write for the whole bdi
@@ -1178,14 +1209,26 @@ static long wb_do_writeback(struct bdi_writeback *wb)
set_bit(WB_writeback_running, &wb->state);
while ((work = get_next_work_item(wb)) != NULL) {
struct wb_completion *done = work->done;
+ bool need_wake_up = false;
trace_writeback_exec(wb->bdi, work);
wrote += wb_writeback(wb, work);
- if (work->auto_free)
+ if (work->single_wait) {
+ WARN_ON_ONCE(work->auto_free);
+ /* paired w/ rmb in wb_wait_for_single_work() */
+ smp_wmb();
+ work->single_done = 1;
+ need_wake_up = true;
+ } else if (work->auto_free) {
kfree(work);
+ }
+
if (done && atomic_dec_and_test(&done->cnt))
+ need_wake_up = true;
+
+ if (need_wake_up)
wake_up_all(&wb->bdi->wb_waitq);
}