Linux 4.15 introduces a new mmap flag MAP_SYNC, which can be used to
guarantee the write persistence to mmap'ed files supporting DAX (e.g.,
files on ext4/xfs file system mounted with '-o dax').
A description of MAP_SYNC and MAP_SHARED_VALIDATE can be found at
https://patchwork.kernel.org/patch/10028151/
In order to make sure that the file metadata is in sync after a fault
while we are writing a shared DAX supporting backend files, this
patch-set enables QEMU to use MAP_SYNC flag for memory-backend-dax-file.
As the DAX vs DMA truncated issue was solved, we refined the code and
send out this feature for the v5 version.
A new auto on/off option 'sync' is added to memory-backend-file:
- on: try to pass MAP_SYNC to mmap(2); if MAP_SYNC is not supported or
'share=off', QEMU will abort
- off: never pass MAP_SYNC to mmap(2)
- auto (default): if MAP_SYNC is supported and 'share=on', work as if
'sync=on'; otherwise, work as if 'sync=off'
Zhang Yi (7):
numa: Fixed the memory leak of numa error message
util/mmap-alloc: switch qemu_ram_mmap() to 'flags' parameter
exec: switch qemu_ram_alloc_from_{file, fd} to the 'flags' parameter
util/mmap-alloc: support MAP_SYNC in qemu_ram_mmap()
util/mmap-alloc: Switch the RAM_SYNC flags to OnOffAuto
hostmem: add more information in error messages
hostmem-file: add 'sync' option
backends/hostmem-file.c | 45 +++++++++++++++++++++++++++++++++--
backends/hostmem.c | 8 ++++---
docs/nvdimm.txt | 20 +++++++++++++++-
exec.c | 9 +++----
include/exec/memory.h | 18 ++++++++++++++
include/exec/ram_addr.h | 1 +
include/qemu/mmap-alloc.h | 20 +++++++++++++++-
include/standard-headers/linux/mman.h | 44 ++++++++++++++++++++++++++++++++++
numa.c | 1 +
qemu-options.hx | 22 ++++++++++++++++-
util/mmap-alloc.c | 26 ++++++++++++++++----
util/oslib-posix.c | 4 +++-
12 files changed, 200 insertions(+), 18 deletions(-)
create mode 100644 include/standard-headers/linux/mman.h
--
2.7.4
