On Thu, Nov 17 2016, Shaohua Li wrote: > On Mon, Nov 14, 2016 at 04:30:21PM +1100, Neil Brown wrote: >> The block tracing infrastructure (accessed with blktrace/blkparse) >> supports the tracing of mapping bios from one device to another. >> This is currently used when a bio in a partition is mapped to the >> whole device, when bios are mapped by dm, and for mapping in md/raid5. >> Other md personalities do not include this tracing yet, so add it. >> >> When a read-error is detected we redirect the request to a different device. >> This could justifiably be seen as a new mapping for the originial bio, >> or a secondary mapping for the bio that errors. This patch uses >> the second option. >> >> When md is used under dm-raid, the mappings are not traced as we do >> not have access to the block device number of the parent. > > Looks the the original sector (the last parameter of trace_block_bio_remap) > isn't correct. > - in linear/raid0, bio_split already updated bio->bi_iter.bi_sector Oh yes, of course. in the common case 'split == bio' so when split->bi_iter.bi_sector is adjusted, bio->.... is as well. I'll fix that, and also add calls to trace_block_split() as appropriate. > - in raid1/raid10, r1_bio->sector is updated before the bio is sent. Here I really think my code is correct. r1_bio->sector is always the address in the array of the request. It is only set once for each r1_bio, and that is before the call to trace_block_io_remap(). Thanks, NeilBrown > > Thanks, > Shaohua
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