From: Benjamin LaHaise <b...@kvack.org>
The recent changes overhauling fs/aio.c introduced a bug that results in the
kioctx not being freed when outstanding kiocbs are cancelled at exit_aio()
time. Specifically, a kiocb that is cancelled has its completion events
discarded by batch_complete_aio(), which then fails to wake up the process
stuck in free_ioctx(). Fix this by removing the event suppression in
batch_complete_aio() and modify the wait_event() condition in free_ioctx()
appropriately.
This patch was tested with the cancel operation in the thread based code
posted yesterday.
Signed-off-by: Benjamin LaHaise <b...@kvack.org>
Cc: Kent Overstreet <koverstr...@google.com>
Cc: Josh Boyer <jwbo...@redhat.com>
Cc: Zach Brown <z...@redhat.com>
Signed-off-by: Andrew Morton <a...@linux-foundation.org>
Signed-off-by: Kent Overstreet <koverstr...@google.com>
---
fs/aio.c | 15 +++------------
1 file changed, 3 insertions(+), 12 deletions(-)
diff --git a/fs/aio.c b/fs/aio.c
index 4dbd240..d2c1a82 100644
--- a/fs/aio.c
+++ b/fs/aio.c
@@ -349,7 +349,9 @@ static void free_ioctx(struct kioctx *ctx)
kunmap_atomic(ring);
while (atomic_read(&ctx->reqs_available) < ctx->nr_events - 1) {
- wait_event(ctx->wait, head != ctx->shadow_tail);
+ wait_event(ctx->wait,
+ (head != ctx->shadow_tail) ||
+ (atomic_read(&ctx->reqs_available) >= ctx->nr_events
- 1));
avail = (head <= ctx->shadow_tail
? ctx->shadow_tail : ctx->nr_events) - head;
@@ -774,17 +776,6 @@ void batch_complete_aio(struct batch_complete *batch)
n = rb_parent(n);
}
- if (unlikely(xchg(&req->ki_cancel,
- KIOCB_CANCELLED) == KIOCB_CANCELLED)) {
- /*
- * Can't use the percpu reqs_available here - could race
- * with free_ioctx()
- */
- atomic_inc(&req->ki_ctx->reqs_available);
- aio_put_req(req);
- continue;
- }
-
if (unlikely(req->ki_eventfd != eventfd)) {
if (eventfd) {
/* Make event visible */
--
1.8.1.3
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