On Fri, Nov 17, 2017 at 02:39:07PM -0600, Eric Sandeen wrote: > On 11/17/17 2:25 PM, Ross Zwisler wrote: > > Add a new 'log_writes' command to xfs_io so that we can add dm-log-writes > > log marks via the external 'dmsetup' executable. It's helpful to allow > > users of xfs_io to adds these marks from within xfs_io instead of waiting > > until after xfs_io exits because then they are able to replay the > > dm-log-writes log up to immediately after another xfs_io operation such as > > mwrite. This isolates the log replay from other operations that happen as > > part of xfs_io exiting (file handles being closed, mmaps being torn down, > > etc.). This also allows users to insert multiple marks between different > > xfs_io commands. > > > > Signed-off-by: Ross Zwisler <ross.zwisler@xxxxxxxxxxxxxxx> > > Suggested-by: Dave Chinner <david@xxxxxxxxxxxxx> > > Without reviewing in detail, what is the advantage of wrapping dmsetup > into xfs_io? My first inclination is that there is none at all, and > xfstests can call dmsetup as easily as they can call xfs_io. No? > > -Eric I commented on this a bit in the changelog for the 2nd patch: It's helpful to allow users of xfs_io to adds these marks from within xfs_io instead of waiting until after xfs_io exits because then they are able to replay the dm-log-writes log up to immediately after another xfs_io operation such as mwrite. This isolates the log replay from other operations that happen as part of xfs_io exiting (file handles being closed, mmaps being torn down, etc.). This also allows users to insert multiple marks between different xfs_io commands. I agree that the shell-out to dmsetup isn't awesome... For the current test I have written I think we can get away with just assuming that the xfs_io exit stuff won't interact too heavily with the dm-log-writes log, and we could potentially move the dmsetup call back into the fstest. This is how I initially had it, and moved it into the C program via shell-out in response to Amir's feedback: https://lists.01.org/pipermail/linux-nvdimm/2017-October/012976.html -- To unsubscribe from this list: send the line "unsubscribe linux-xfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
