io_wq: add get/put_work handlers to io_wq_create()
For cancellation, we need to ensure that the work item stays valid for
as long as ->cur_work is valid. Right now we can't safely dereference
the work item even under the wqe->lock, because while the ->cur_work
pointer will remain valid, the work could be completing and be freed
in parallel.
Only invoke ->get/put_work() on items we know that the caller queued
themselves. Add IO_WQ_WORK_INTERNAL for io-wq to use, which is needed
when we're queueing a flush item, for instance.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/fs/io-wq.h b/fs/io-wq.h
index cc50754..4b29f92 100644
--- a/fs/io-wq.h
+++ b/fs/io-wq.h
@@ -10,6 +10,7 @@ enum {
IO_WQ_WORK_NEEDS_USER = 8,
IO_WQ_WORK_NEEDS_FILES = 16,
IO_WQ_WORK_UNBOUND = 32,
+ IO_WQ_WORK_INTERNAL = 64,
IO_WQ_HASH_SHIFT = 24, /* upper 8 bits are used for hash key */
};
@@ -34,8 +35,12 @@ struct io_wq_work {
(work)->files = NULL; \
} while (0) \
+typedef void (get_work_fn)(struct io_wq_work *);
+typedef void (put_work_fn)(struct io_wq_work *);
+
struct io_wq *io_wq_create(unsigned bounded, struct mm_struct *mm,
- struct user_struct *user);
+ struct user_struct *user,
+ get_work_fn *get_work, put_work_fn *put_work);
void io_wq_destroy(struct io_wq *wq);
void io_wq_enqueue(struct io_wq *wq, struct io_wq_work *work);
