Some improvements in latest kernel allow to boost Lustre performance (on some workloads we can expect up to 30% better, you can have more details on it if you read this LUG presentation [Lustre osd-ldiskfs on kernel 4.12.8|http://cdn.opensfs.org/wp-content/uploads/2018/04/Delbary-Lustre_Server_On_Kernel_4_12_8.pdf]
This LU purposes patches to support ldiskfs backend.
When we began this work on commit "1defa62a19e71c021ec2cf9fc9e0481e9ab962e0", we needed patches for ldiskfs and osd-ldiskfs. Right now people have done the job for the osd-ldiskfs, i submit only the patches for ldiskfs and some autoconf file (to specify explicitly that's for kernel 4.12.8).
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