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commit54aa7f2330upstream. Heming reported a BUG when using io_uring doing link-cp on ocfs2. [1] Do the following steps can reproduce this BUG: mount -t ocfs2 /dev/vdc /mnt/ocfs2 cp testfile /mnt/ocfs2/ ./link-cp /mnt/ocfs2/testfile /mnt/ocfs2/testfile.1 umount /mnt/ocfs2 Then umount will fail, and it outputs: umount: /mnt/ocfs2: target is busy. While tracing umount, it blames mnt_get_count() not return as expected. Do a deep investigation for fget()/fput() on related code flow, I've finally found that fget() leaks since ocfs2 doesn't support nowait buffered read. io_issue_sqe |-io_assign_file // do fget() first |-io_read |-io_iter_do_read |-ocfs2_file_read_iter // return -EOPNOTSUPP |-kiocb_done |-io_rw_done |-__io_complete_rw_common // set REQ_F_REISSUE |-io_resubmit_prep |-io_req_prep_async // override req->file, leak happens This was introduced by commita196c78b54in v5.18. Fix it by don't re-assign req->file if it has already been assigned. [1] https://lore.kernel.org/ocfs2-devel/ab580a75-91c8-d68a-3455-40361be1bfa8@linux.alibaba.com/T/#t Fixes:a196c78b54("io_uring: assign non-fixed early for async work") Cc: <stable@vger.kernel.org> Reported-by: Heming Zhao <heming.zhao@suse.com> Signed-off-by: Joseph Qi <joseph.qi@linux.alibaba.com> Cc: Xiaoguang Wang <xiaoguang.wang@linux.alibaba.com> Link: https://lore.kernel.org/r/20230228045459.13524-1-joseph.qi@linux.alibaba.com Signed-off-by: Jens Axboe <axboe@kernel.dk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.