Joe Lawrence reported a list_add corruption with 4.6-rc1 when
testing some custom md administration code that made it's own
block device nodes for the md array. The simple test loop of:
for i in {0..100}; do
mknod --mode=0600 $tmp/tmp_node b $MAJOR $MINOR
mdadm --detail --export $tmp/tmp_node > /dev/null
rm -f $tmp/tmp_node
done
Would produce this warning in bd_acquire() when mdadm opened the
device node:
list_add double add: new=ffff88043831c7b8, prev=ffff8804380287d8, next=ffff88043831c7b8.
And then produce this from bd_forget from kdevtmpfs evicting a block
dev inode:
list_del corruption. prev->next should be ffff8800bb83eb10, but was ffff88043831c7b8
This is a regression caused by commit c19b3b05 ("xfs: mode di_mode
to vfs inode"). The issue is that xfs_inactive() frees the
unlinked inode, and the above commit meant that this freeing zeroed
the mode in the struct inode. The problem is that after evict() has
called ->evict_inode, it expects the i_mode to be intact so that it
can call bd_forget() or cd_forget() to drop the reference to the
block device inode attached to the XFS inode.
In reality, the only thing we do in xfs_fs_evict_inode() that is not
generic is call xfs_inactive(). We can move the xfs_inactive() call
to xfs_fs_destroy_inode() without any problems at all, and this
will leave the VFS inode intact until it is completely done with it.
So, remove xfs_fs_evict_inode(), and do the work it used to do in
->destroy_inode instead.
cc: <stable@vger.kernel.org> # 4.6
Reported-by: Joe Lawrence <joe.lawrence@stratus.com>
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>