On Fri, 20 Nov 2015 16:23:16 +0800 Ryan Ding <ryan.d...@oracle.com> wrote:
> In the current implementation of unaligned aio+dio, lock order behave as > follow: > > in user process context: > -> call io_submit() > -> get i_mutex > <== window1 > -> get ip_unaligned_aio > -> submit direct io to block device > -> release i_mutex > -> io_submit() return > > in dio work queue context(the work queue is created in __blockdev_direct_IO): > -> release ip_unaligned_aio > <== window2 > -> get i_mutex > -> clear unwritten flag & change i_size > -> release i_mutex > > There is a limitation to the thread number of dio work queue. 256 at default. > If all 256 thread are in the above 'window2' stage, and there is a user > process > in the 'window1' stage, the system will became deadlock. Since the user > process > hold i_mutex to wait ip_unaligned_aio lock, while there is a direct bio hold > ip_unaligned_aio mutex who is waiting for a dio work queue thread to be > schedule. But all the dio work queue thread is waiting for i_mutex lock in > 'window2'. > > This case only happened in a test which send a large number(more than 256) of > aio at one io_submit() call. > > My design is to remove ip_unaligned_aio lock. Change it to a sync io instead. > Just like ip_unaligned_aio lock, serialize the unaligned aio dio. So this patch series is a bunch of fixes against your previous patch series: ocfs2-add-ocfs2_write_type_t-type-to-identify-the-caller-of-write.patch ocfs2-use-c_new-to-indicate-newly-allocated-extents.patch ocfs2-test-target-page-before-change-it.patch ocfs2-do-not-change-i_size-in-write_end-for-direct-io.patch ocfs2-return-the-physical-address-in-ocfs2_write_cluster.patch ocfs2-record-unwritten-extents-when-populate-write-desc.patch ocfs2-fix-sparse-file-data-ordering-issue-in-direct-io.patch ocfs2-code-clean-up-for-direct-io.patch correct? Those patches are languishing a bit, awaiting review/ack. I'll send everything out for a round of review soon... _______________________________________________ Ocfs2-devel mailing list Ocfs2-devel@oss.oracle.com https://oss.oracle.com/mailman/listinfo/ocfs2-devel
