writeback: ensure that WB_SYNC_NONE writeback with sb pinned is sync
Even if the writeout itself isn't a data integrity operation, we need
to ensure that the caller doesn't drop the sb umount sem before we
have actually done the writeback.
This is a fixup for commit e913fc82.
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index 0f62957..76f546d 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -193,7 +193,8 @@
}
static void bdi_alloc_queue_work(struct backing_dev_info *bdi,
- struct wb_writeback_args *args)
+ struct wb_writeback_args *args,
+ int wait)
{
struct bdi_work *work;
@@ -205,6 +206,8 @@
if (work) {
bdi_work_init(work, args);
bdi_queue_work(bdi, work);
+ if (wait)
+ bdi_wait_on_work_clear(work);
} else {
struct bdi_writeback *wb = &bdi->wb;
@@ -279,7 +282,7 @@
args.for_background = 1;
}
- bdi_alloc_queue_work(bdi, &args);
+ bdi_alloc_queue_work(bdi, &args, sb_locked);
}
/*
@@ -909,6 +912,7 @@
while ((work = get_next_work_item(bdi, wb)) != NULL) {
struct wb_writeback_args args = work->args;
+ int post_clear;
/*
* Override sync mode, in case we must wait for completion
@@ -916,11 +920,13 @@
if (force_wait)
work->args.sync_mode = args.sync_mode = WB_SYNC_ALL;
+ post_clear = WB_SYNC_ALL || args.sb_pinned;
+
/*
* If this isn't a data integrity operation, just notify
* that we have seen this work and we are now starting it.
*/
- if (args.sync_mode == WB_SYNC_NONE)
+ if (!post_clear)
wb_clear_pending(wb, work);
wrote += wb_writeback(wb, &args);
@@ -929,7 +935,7 @@
* This is a data integrity writeback, so only do the
* notification when we have completed the work.
*/
- if (args.sync_mode == WB_SYNC_ALL)
+ if (post_clear)
wb_clear_pending(wb, work);
}
@@ -1000,7 +1006,7 @@
if (!bdi_has_dirty_io(bdi))
continue;
- bdi_alloc_queue_work(bdi, &args);
+ bdi_alloc_queue_work(bdi, &args, 0);
}
rcu_read_unlock();
