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[PATCH 2/2] xfs: fix splice/direct-IO deadlock

To: linux-fsdevel@xxxxxxxxxxxxxxx
Subject: [PATCH 2/2] xfs: fix splice/direct-IO deadlock
From: Dave Chinner <david@xxxxxxxxxxxxx>
Date: Mon, 18 Jul 2011 14:04:44 +1000
Cc: linux-kernel@xxxxxxxxxxxxxxx, xfs@xxxxxxxxxxx
In-reply-to: <1310961884-11634-1-git-send-email-david@xxxxxxxxxxxxx>
References: <1310961884-11634-1-git-send-email-david@xxxxxxxxxxxxx>
From: Dave Chinner <dchinner@xxxxxxxxxx>

lockdep reports splice vs direct-io write lock inversions due to
generic_file_splice_write() taking the inode->i_mutex inside
XFS_IOLOCK_EXCL context. These lock contexts are inverted, hence can
deadlock.  Use generic_file_splice_write_unlocked() because the
i_mutex does not need to be held over the operations that are done
in the XFS splice write path.

Signed-off-by: Dave Chinner <dchinner@xxxxxxxxxx>
 fs/xfs/linux-2.6/xfs_file.c |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)

diff --git a/fs/xfs/linux-2.6/xfs_file.c b/fs/xfs/linux-2.6/xfs_file.c
index f51a384..1e641e6 100644
--- a/fs/xfs/linux-2.6/xfs_file.c
+++ b/fs/xfs/linux-2.6/xfs_file.c
@@ -463,7 +463,8 @@ xfs_file_splice_write(
        trace_xfs_file_splice_write(ip, count, *ppos, ioflags);
-       ret = generic_file_splice_write(pipe, outfilp, ppos, count, flags);
+       ret = generic_file_splice_write_unlocked(pipe, outfilp, ppos,
+                                               count, flags);
        xfs_aio_write_isize_update(inode, ppos, ret);

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