On 8/10/17 2:22 PM, Eric Sandeen wrote: > On 8/10/17 2:12 PM, Darrick J. Wong wrote: >> On Thu, Aug 10, 2017 at 07:46:35PM +0300, Nikolay Borisov wrote: >>> >>> >>> On 10.08.2017 19:13, Darrick J. Wong wrote: >>>> We don't decrement len each time through the ioctl loop? Doesn't that >>>> cause us to request and retrieve rows for ranges we don't want? >>> >>> Hm, you are right, I believe on every iteration we should do: >>> >>> len -= last_logical - start_offset >> >> start_offset doesn't change, right? >> >> I would think len -= last_logical - fiemap->fm_start. >> >> Or just calculate end_offset = start_offset + length and set >> fiemap->fm_length = end_offset - last_logical... >> >> ...though now that I look at that file even closer I wonder what is >> going on with that outer while loop counting extents? Does -n exist to >> let users cap the number of records to print, even if that means we >> don't make it to the end of the range requested? > > -n should simply be the size of each fiemap request, i.e. how many to > request and fill on each iteration. It should not affect how many > get printed in the end. > > At least that's how xfs_bmap is supposed to work, and therefore in theory > how xfs_io's fiemap should work. ... except apparently that is not actually how it works :( -Eric -- 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
