The io_cancel() syscall allows for cancellation of iocbs in flight to
generate a completion event. The current behaviour of batch_complete_aio()
is to suppress all completion events. Some types of asynchronous operations
cannot be cancelled synchronously, and must generate a completion event at
some point after the io_cancel() syscall. Instead, only suppress
completion events during kioctx teardown by free_ioctx().
Signed-off-by: Benjamin LaHaise <bcrl@xxxxxxxxx>
---
fs/aio.c | 6 +++++-
1 files changed, 5 insertions(+), 1 deletions(-)
diff --git a/fs/aio.c b/fs/aio.c
index 46f9dd0..1bcb818 100644
--- a/fs/aio.c
+++ b/fs/aio.c
@@ -81,6 +81,7 @@ struct kioctx {
/* sys_io_setup currently limits this to an unsigned int */
unsigned max_reqs;
+ unsigned dead;
unsigned long mmap_base;
unsigned long mmap_size;
@@ -311,6 +312,7 @@ static void free_ioctx(struct kioctx *ctx)
struct kiocb *req;
unsigned cpu, head, avail;
+ ctx->dead = 1;
spin_lock_irq(&ctx->ctx_lock);
while (!list_empty(&ctx->active_reqs)) {
@@ -749,7 +751,9 @@ void batch_complete_aio(struct batch_complete *batch)
n = rb_parent(n);
}
- if (unlikely(xchg(&req->ki_cancel,
+ /* Suppress cancelled events if free_ioctx() is in progress. */
+ if (unlikely(req->ki_ctx->dead &&
+ xchg(&req->ki_cancel,
KIOCB_CANCELLED) == KIOCB_CANCELLED)) {
/*
* Can't use the percpu reqs_available here - could race
--
1.7.4.1
--
"Thought is the essence of where you are now."
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