Hi Dan, On Sat, May 6, 2017 at 4:21 AM, Linux Kernel Mailing List <linux-kernel@xxxxxxxxxxxxxxx> wrote: > Web: https://git.kernel.org/torvalds/c/b0686260fecaa924d8eff2ace94bee70506bc308 > Commit: b0686260fecaa924d8eff2ace94bee70506bc308 > Parent: d8f07aee3f2fd959878bf614d4e984900018eb9e > Refname: refs/heads/master > Author: Dan Williams <dan.j.williams@xxxxxxxxx> > AuthorDate: Thu Jan 26 20:37:35 2017 -0800 > Committer: Dan Williams <dan.j.williams@xxxxxxxxx> > CommitDate: Thu Apr 20 11:57:52 2017 -0700 > > dax: introduce dax_direct_access() > > Replace bdev_direct_access() with dax_direct_access() that uses > dax_device and dax_operations instead of a block_device and > block_device_operations for dax. Once all consumers of the old api have > been converted bdev_direct_access() will be deleted. > > Given that block device partitioning decisions can cause dax page > alignment constraints to be violated this also introduces the > bdev_dax_pgoff() helper. It handles calculating a logical pgoff relative > to the dax_device and also checks for page alignment. > > Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx> This looks like a fairly innocent change... > --- > block/Kconfig | 1 + > drivers/dax/super.c | 39 +++++++++++++++++++++++++++++++++++++++ > fs/block_dev.c | 14 ++++++++++++++ > include/linux/blkdev.h | 1 + > include/linux/dax.h | 2 ++ > 5 files changed, 57 insertions(+) > > diff --git a/block/Kconfig b/block/Kconfig > index e9f780f815f5..93da7fc3f254 100644 > --- a/block/Kconfig > +++ b/block/Kconfig > @@ -6,6 +6,7 @@ menuconfig BLOCK > default y > select SBITMAP > select SRCU > + select DAX > help > Provide block layer support for the kernel. ... but it is not: now DAX is always enabled if you use block devices. $ bloat-o-meter vmlinux.nodax vmlinux.dax | head add/remove: 59/0 grow/shrink: 10/1 up/down: 6048/-8 (6040) function old new delta dax_host_list - 4096 +4096 alloc_dax - 306 +306 dax_fs_init - 230 +230 dax_get_by_host - 128 +128 dax_sops - 100 +100 dax_srcu - 90 +90 dax_direct_access - 80 +80 bdev_dax_pgoff - 80 +80 Does all block device access really needs DAX enabled? Furthermore: Maximum number of Device-DAX instances (NR_DEV_DAX) [32768] (NEW) ? There is no help available for this option. Symbol: NR_DEV_DAX [=32768] Type : integer Range : [256 2147483647] Prompt: Maximum number of Device-DAX instances Location: -> Device Drivers -> DAX: direct access to differentiated memory (DAX [=y]) Defined at drivers/dax/Kconfig:31 Depends on: DAX [=y] What should I answer here? "256" already sounds like a large number to me, "32768" sounds huge, and "2147483647" sounds insane? But perhaps this doesn't really mean what I would expect... Can you please add some help for this option? Thanks! Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds
