On 2018/4/14 6:46 AM, Eric Wheeler wrote: > Hello all, > > We are running bcache in 4.1.49 with both the cache and backing device > having 4k blocks. The disk stack is DRBD->dm-thin->bcache->[sdc->sdb] > Where sdc is the cache. > > Sometimes we get errors like the following: > > [432015.934869] block drbd8065: Began resync as SyncTarget (will sync 880 KB [220 bits set]). > [432015.949469] sd 0:0:0:1: [sdb] Unaligned block number requested: sector_size=4096, block=15724561783, blk_rq=9 > [432015.950347] sd 0:0:0:2: [sdc] Unaligned block number requested: sector_size=4096, block=353041040, blk_rq=7 > [432015.951146] bcache: bch_count_io_errors() dm-6: IO error on reading from cache, recovering > [432015.952015] block drbd8065: read: error=-5 s=19281488s > [432015.952866] block drbd8065: Local IO failed in drbd_endio_read_sec_final. > [432015.953777] sd 0:0:0:2: [sdc] Unaligned block number requested: sector_size=4096, block=387084784, blk_rq=7 > [432015.954710] bcache: bch_count_io_errors() dm-6: IO error on reading from cache, recovering > [432015.959037] sd 0:0:0:1: [sdb] Unaligned block number requested: sector_size=4096, block=15725385535, blk_rq=1 > [432015.959938] block drbd8065: read: error=-5 s=19391384s > [432015.960862] block drbd8065: Local IO failed in drbd_endio_read_sec_final. > > > Note that 15724561783 is not divisible by 8, thus it is unaligned to 4k > blocks. > > Does anyone know if the bcache code is enforcing correct alignment? > > Is there any way that bcache could introduce misalignment? > > We ran blockdev --getbsz and --getpbsz all the way down the stack and > everything reports 4k. Hi Eric, Do you use 4.1 stable tree, or with your extra patches ? It would be helpful if I may access your kernel tree. So far I cannot tell where the problem is, I just feel there might be some hidden issue triggered by 4KB sector size hard drive. Maybe adding a garden code to detect unaligned I/O request from bcache will be helpful to diagnose the root cause. Thanks. Coly Li -- To unsubscribe from this list: send the line "unsubscribe linux-bcache" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
