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e63890f38a
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.
[akpm@linux-foundation.org: remove OCFS2_IOCB_UNALIGNED_IO, per Junxiao Bi]
Signed-off-by: Ryan Ding <ryan.ding@oracle.com>
Reviewed-by: Junxiao Bi <junxiao.bi@oracle.com>
Cc: Joseph Qi <joseph.qi@huawei.com>
Cc: Mark Fasheh <mfasheh@suse.de>
Cc: Joel Becker <jlbec@evilplan.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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| .. | ||
| cluster | ||
| dlm | ||
| dlmfs | ||
| acl.c | ||
| acl.h | ||
| alloc.c | ||
| alloc.h | ||
| aops.c | ||
| aops.h | ||
| blockcheck.c | ||
| blockcheck.h | ||
| buffer_head_io.c | ||
| buffer_head_io.h | ||
| dcache.c | ||
| dcache.h | ||
| dir.c | ||
| dir.h | ||
| dlmglue.c | ||
| dlmglue.h | ||
| export.c | ||
| export.h | ||
| extent_map.c | ||
| extent_map.h | ||
| file.c | ||
| file.h | ||
| filecheck.c | ||
| filecheck.h | ||
| heartbeat.c | ||
| heartbeat.h | ||
| inode.c | ||
| inode.h | ||
| ioctl.c | ||
| ioctl.h | ||
| journal.c | ||
| journal.h | ||
| Kconfig | ||
| localalloc.c | ||
| localalloc.h | ||
| locks.c | ||
| locks.h | ||
| Makefile | ||
| mmap.c | ||
| mmap.h | ||
| move_extents.c | ||
| move_extents.h | ||
| namei.c | ||
| namei.h | ||
| ocfs1_fs_compat.h | ||
| ocfs2.h | ||
| ocfs2_fs.h | ||
| ocfs2_ioctl.h | ||
| ocfs2_lockid.h | ||
| ocfs2_lockingver.h | ||
| ocfs2_trace.h | ||
| quota.h | ||
| quota_global.c | ||
| quota_local.c | ||
| refcounttree.c | ||
| refcounttree.h | ||
| reservations.c | ||
| reservations.h | ||
| resize.c | ||
| resize.h | ||
| slot_map.c | ||
| slot_map.h | ||
| stack_o2cb.c | ||
| stack_user.c | ||
| stackglue.c | ||
| stackglue.h | ||
| suballoc.c | ||
| suballoc.h | ||
| super.c | ||
| super.h | ||
| symlink.c | ||
| symlink.h | ||
| sysfile.c | ||
| sysfile.h | ||
| uptodate.c | ||
| uptodate.h | ||
| xattr.c | ||
| xattr.h | ||