Messages in this thread | | | Subject | Re: [PATCH v1 0/4] block: fix bio_will_gap() | From | Sagi Grimberg <> | Date | Sun, 21 Feb 2016 11:41:00 +0200 |
| |
> Hi Guys, > > The bio passed to bio_will_gap() may be fast cloned from upper > layer(dm, md, bcache, fs, ...), or from bio splitting in block > core. Unfortunately bio_will_gap() just figures out the last > bvec via 'bi_io_vec[prev->bi_vcnt - 1]' directly, and this way > is obviously wrong in case of fast-cloned bio. > > It is observed that lots of BIOs are still merged even if > the virt boundary limit is violated by the merge, and the issue > was reported from Sagi Grimberg. > > This patch introduces two helpers for getting the first and last > bvec of one bio and applys them to fix the issue. Sagi tested > the last patchset and confirmed the fix. > > V1: > - get bvec directly for non-cloned bio > - implement bio_get_last_bvec() with single bio_advance_iter(), > and avoid to use bio_for_each_segment() which looks a bit inefficient > - avoid to double check queue_virt_boundary() in bio_will_gap()
Thanks Ming,
Jens, can this make the next 4.5-rc since this regression was detected in 4.5?
Thanks, Sagi.
| |