On Tue, Apr 11 2017, Shaohua Li wrote: > On Wed, Apr 05, 2017 at 02:05:50PM +1000, Neil Brown wrote: >> This is part of my little project to make bio splitting >> in Linux uniform and dead-lock free, in a way that will mean >> that we can get rid of all the bioset threads. >> >> The basic approach is that when a bio needs to be split, we call >> bio_split(), bio_chain() and then generic_make_request(). >> We then proceed to handle the remainder without further splitting. >> Recent changes to generic_make_request() ensure that this will >> be safe from deadlocks, providing each bioset is used only once >> in the stack. >> >> This leads to simpler code in various places. In particular, the >> splitting of bios that is needed to work around known bad blocks >> is now much less complex. There is only ever one r1bio per bio. >> >> As you can see from >> 10 files changed, 335 insertions(+), 540 deletions(-) >> there is a net reduction in code. > > Looks good and makes code simpler, applied, thanks Neil! The patch 1 and 6 need > comments in the code to explain how deadlock is avoided though. Care to send a > new patch? It isn't clear to me what sort of comment you want, or where it should go. It might make sense to have a comment near bio_split() explaining how to use it (i.e. explaining the pattern used in various patches here), but I don't see what sort of comments would help in raid1.c or raid10.c ?? Thanks, NeilBrown
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