From 9e985787750db8aae87f02b67e908f28ac4d6b83 Mon Sep 17 00:00:00 2001 From: Changwei Ge Date: Fri, 2 Nov 2018 15:48:11 -0700 Subject: [PATCH] ocfs2: don't use iocb when EIOCBQUEUED returns When -EIOCBQUEUED returns, it means that aio_complete() will be called from dio_complete(), which is an asynchronous progress against write_iter. Generally, IO is a very slow progress than executing instruction, but we still can't take the risk to access a freed iocb. And we do face a BUG crash issue. Using the crash tool, iocb is obviously freed already. crash> struct -x kiocb ffff881a350f5900 struct kiocb { ki_filp = 0xffff881a350f5a80, ki_pos = 0x0, ki_complete = 0x0, private = 0x0, ki_flags = 0x0 } And the backtrace shows: ocfs2_file_write_iter+0xcaa/0xd00 [ocfs2] aio_run_iocb+0x229/0x2f0 do_io_submit+0x291/0x540 SyS_io_submit+0x10/0x20 system_call_fastpath+0x16/0x75 Link: http://lkml.kernel.org/r/1523361653-14439-1-git-send-email-ge.changwei@h3c.com Signed-off-by: Changwei Ge Reviewed-by: Andrew Morton Cc: Mark Fasheh Cc: Joel Becker Cc: Junxiao Bi Cc: Joseph Qi Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/ocfs2/file.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/fs/ocfs2/file.c b/fs/ocfs2/file.c index fe570824b991..d640c5f8a85d 100644 --- a/fs/ocfs2/file.c +++ b/fs/ocfs2/file.c @@ -2343,7 +2343,7 @@ static ssize_t ocfs2_file_write_iter(struct kiocb *iocb, written = __generic_file_write_iter(iocb, from); /* buffered aio wouldn't have proper lock coverage today */ - BUG_ON(written == -EIOCBQUEUED && !(iocb->ki_flags & IOCB_DIRECT)); + BUG_ON(written == -EIOCBQUEUED && !direct_io); /* * deep in g_f_a_w_n()->ocfs2_direct_IO we pass in a ocfs2_dio_end_io @@ -2463,7 +2463,7 @@ static ssize_t ocfs2_file_read_iter(struct kiocb *iocb, trace_generic_file_read_iter_ret(ret); /* buffered aio wouldn't have proper lock coverage today */ - BUG_ON(ret == -EIOCBQUEUED && !(iocb->ki_flags & IOCB_DIRECT)); + BUG_ON(ret == -EIOCBQUEUED && !direct_io); /* see ocfs2_file_write_iter */ if (ret == -EIOCBQUEUED || !ocfs2_iocb_is_rw_locked(iocb)) { -- 2.30.2