Currently, active_aligned_reads and nr_pending used as counters are atomic types. Therefore, when inc/dec in a multi-core results in conflicts. To solve this problem, use "percpu_ref" counters that can avoid conflicts and maintain consistency. Switch modes of percpu_ref to achieve both consistency and conflict avoidance. During normal operations such as inc/dec, it operates as percpu mode. When consistency is required, it operates as atomic mode. The operations that require consistency are as follows: ・Zero check for the counter ・All operations in RAID 1/10 Patches 1, 3, 6 change active_aligned_reads, and patches 2, 4, 5, 7 to 11 change nr_pending. nr_pending temporarily switch from percpu mode to atomic mode in patch 7. This is to reduce the amount of changes from patches 8 to 10. Finally, nr_pending switch from atomic mode to percpu mode in patch 11. Keisuke TADA (11): add infra for active_aligned_reads changes add infra for nr_pending changes workaround for inconsistency of config state in takeover minimize execution of zero check for nr_pending match the type of variables to percpu_ref avoid conflicts in active_aligned_reads operations change the type of nr_pending from atomic_t to percpu_ref add atomic mode switching in RAID 1/10 add atomic mode switching when removing disk add atomic mode switching when I/O completion avoid conflicts in nr_pending operations drivers/md/md-bitmap.c | 2 +- drivers/md/md.c | 40 +++++++++++++++--- drivers/md/md.h | 62 ++++++++++++++++++++++++---- drivers/md/raid1.c | 37 +++++++++++------ drivers/md/raid10.c | 60 ++++++++++++++++----------- drivers/md/raid5-cache.c | 4 +- drivers/md/raid5.c | 89 +++++++++++++++++++++++++++------------- drivers/md/raid5.h | 17 +++++++- 8 files changed, 230 insertions(+), 81 deletions(-) base-commit: fcf3f7e2fc8a53a6140beee46ec782a4c88e4744 -- 2.34.1
