On Mon, Oct 19, 2015 at 08:37:45AM +1100, Dave Chinner wrote: > On Sat, Oct 17, 2015 at 02:45:18PM -0400, Theodore Ts'o wrote: > > Like FSSTRESS_AVOID and FSX_AVOID, XFS_IO_AVOID can be used to avoid > > using various advanced file system features such as "fpunch" > > "fcollapse", "finsert", or "zero". Tests that require an xfs_io > > command which is included in the space-separated list found in the > > XFS_IO_AVOID environment variable will be skipped using _notrun. > > This tells me what the change does, not why you need it. We didn't go into as much detail for FSX_AVOID and FSSTRESS_AVOID, but it's basically for the same reason. Sometimes we might want to exclude certain operational modes from the xfststs. As one example, currently xfstests doesn't understand the difference between the allocation cluster size and the block size. In the case of collapse/insert range, it means operations need to be done in cluster-aligned chunks, as opposed to block-aligned clusters. So to suppress test noise it's nice if we can suppress all attempts to use insert_range/collapse_range while running a test --- and using FSX_AVOID and FSSTRESS_AVOID isn't sufficient for this purpose. (As you may recall, I while back had a test patch allowed the file system to claim that it doesn't support collapse or insert range, and you and Eric argued that the right way to handle this was using environment variables like FSX_AVOID and FSSTRESS_AVOID to cause xfstests to avoid to use certain fallocate operational modes. XFS_IO_AVOID is basically an extension of that same functionality. Without this, hacking the kernel to always fail certain fallocate mode is still needed in order to force certain tests to be skipped.) As another example, recently I was trying to debug a memory leak, both on the most recent version of the kernel, as well as old stable kernels, and it's very useful to be able to see if a particular bug might be caused by say, buggy collapse range support. So I wanted to be able to suppress all use of collapse range by being able to do something as simple as "gce-xfstests --no-collapse". This gets expanded to setting the FSX_AVOID, FSSTRESS_AVOID, and XFS_IO_AVOID environment variables. This way it becomes easier to see if certain test failures go away if an fallocate operational mode is suppressed --- and hence, allows us to localize the failure to collapse_range or insert_range. Cheers, - Ted -- To unsubscribe from this list: send the line "unsubscribe fstests" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
