The only caller of ->readpages() is from read-ahead, yet we don't submit IO flagged with REQ_RAHEAD. This means we don't see it in blktrace, for instance, which is a shame. We already make assumptions about ->readpages() just being for read-ahead in the mpage implementation, using readahead_gfp_mask(mapping) as out GFP mask of choice. This small series fixes up mpage_readpages() to submit with REQ_RAHEAD, which takes care of file systems using mpage_readpages(). The last two fixup ext4 and btrfs. -- Jens Axboe
