On 1/29/16 5:40 PM, Ross Zwisler wrote:
> On Fri, Jan 29, 2016 at 04:05:31PM -0700, Ross Zwisler wrote:
>> Today I was trying to get real-time devices working with XFS, and both a
>> manual pwrite() to a real-time device and xfs_rtcp end up with a lockdep spat
>> followed by a kernel BUG. This behavior is consistent between kernel versions
>> v4.4 and v4.5-rc1. I initially found this using some pmem block devices, but
>> it also happens with BRD.
>
> This also happens with an mmap on the real-time file followed by a write.
> Essentially I think that any path that tries to allocate a block for the real
> time file his this same BUG.
Looks like an oversight from
commit eef334e5776c8ef547ada4cec17549929fe590b4
Author: Christoph Hellwig <hch@xxxxxxxxxxxxx>
Date: Fri Dec 6 12:30:17 2013 -0800
xfs: assert that we hold the ilock for extent map access
Make sure that xfs_bmapi_read has the ilock held in some way, and that
xfs_bmapi_write, xfs_bmapi_delay, xfs_bunmapi and xfs_iread_extents are
called with the ilock held exclusively.
Signed-off-by: Christoph Hellwig <hch@xxxxxx>
Reviewed-by: Dave Chinner <dchinner@xxxxxxxxxx>
Signed-off-by: Ben Myers <bpm@xxxxxxx>
I think all we have to do is lock it for read here, I'll send a patch and
Dave or Christoph can smack me down if I'm wrong ;)
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