On Tue, 15 Sep 2020, Matthew Wilcox wrote: > On Tue, Sep 15, 2020 at 08:34:41AM -0400, Mikulas Patocka wrote: > > - when the fsck.nvfs tool mmaps the device /dev/pmem0, the kernel uses > > buffer cache for the mapping. The buffer cache slows does fsck by a factor > > of 5 to 10. Could it be possible to change the kernel so that it maps DAX > > based block devices directly? > > Oh, because fs/block_dev.c has: > .mmap = generic_file_mmap, > > I don't see why we shouldn't have a blkdev_mmap modelled after > ext2_file_mmap() with the corresponding blkdev_dax_vm_ops. Yes, that's possible - and we whould also have to rewrite methods read_iter and write_iter on DAX block devices, so that they are coherent with mmap. Mikulas
