On Thu, Dec 17, 2020 at 12:12:46PM +0000, Matthew Wilcox wrote: > ehh ... probably an off-by-one. Does subtracting 1 from contig_end fix it? > I'll spool up a test VM shortly and try it out. Yes, this fixed it: - u64 contig_end = contig_start + readahead_batch_length(rac); + u64 contig_end = contig_start + readahead_batch_length(rac) - 1;