[PATCH 2/2] io_uring: fix linked deferred ->files cancellation

Pavel Begunkov
2020-09-05T21:47:51Z

While looking for ->files in ->defer_list, consider that requests there
may actually be links.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
---
fs/io_uring.c | 23 +++++++++++++++++++++--
1 file changed, 21 insertions(+), 2 deletions(-)

diff --git a/fs/io_uring.c b/fs/io_uring.c
index 20b647afe206..f56e2cad97cc 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -8018,6 +8018,26 @@ static bool io_match_link(struct io_kiocb *preq, struct io_kiocb *req)
return false;
}

+static inline bool io_match_files(struct io_kiocb *req,
+ struct files_struct *file)
+{
+ return (req->flags & REQ_F_WORK_INITIALIZED) && req->work.files == file;
+}
+
+static bool io_match_link_files(struct io_kiocb *req,
+ struct files_struct *files)
+{
+ struct io_kiocb *link;
+
+ if (io_match_files(req, files))
+ return true;
+ if (req->flags & REQ_F_LINK_HEAD)
+ list_for_each_entry(link, &req->link_list, link_list)
+ if (io_match_files(link, files))
+ return true;
+ return false;
+}
+
/*
* We're looking to cancel 'req' because it's holding on to our files, but
* 'req' could be a link to another request. See if it is, and cancel that
@@ -8100,8 +8120,7 @@ static void io_cancel_defer_files(struct io_ring_ctx *ctx,

spin_lock_irq(&ctx->completion_lock);
list_for_each_entry_reverse(de, &ctx->defer_list, list)
- if ((de->req->flags & REQ_F_WORK_INITIALIZED)
- && de->req->work.files == files) {
+ if (io_match_link_files(de->req, files)) {
list_cut_position(&list, &ctx->defer_list, &de->list);
break;
}
--
2.24.0