| Message ID | cover.1542699775.git.yi.z.zhang@linux.intel.com (mailing list archive) |
|---|---|
| Headers | show |
| Series | nvdimm: support MAP_SYNC for memory-backend-file | expand |
Ping for any review/comments Thanks Yi On 2018-11-20 at 15:47:58 +0800, Zhang Yi wrote: > 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' Changes in v5: * Add patch 1 to fix a memory leak issue. * Refine the patch 4-6 * Remove the patch 3 as we already change the parameter from "shared" to "flags" Changes in v4: * Add patch 1-3 to switch some functions to a single 'flags' parameters. (Michael S. Tsirkin) * v3 patch 1-3 become v4 patch 4-6. * Patch 4: move definitions of MAP_SYNC and MAP_SHARED_VALIDATE to a new header file under include/standard-headers/linux/. (Michael S. Tsirkin) * Patch 6: refine the description of the 'sync' option. (Michael S. Tsirkin) Changes in v3: * Patch 1: add MAP_SHARED_VALIDATE in both sync=on and sync=auto cases, and add back the retry mechanism. MAP_SYNC will be ignored by Linux kernel 4.15 if MAP_SHARED_VALIDATE is missed. * Patch 1: define MAP_SYNC and MAP_SHARED_VALIDATE as 0 on non-Linux platforms in order to make qemu_ram_mmap() compile on those platforms. * Patch 2&3: include more information in error messages of memory-backend in hope to help user to identify the error. (Dr. David Alan Gilbert) * Patch 3: fix typo in the commit message. (Dr. David Alan Gilbert) Changes in v2: * Add 'sync' option to control the use of MAP_SYNC. (Eduardo Habkost) * Remove the unnecessary set of MAP_SHARED_VALIDATE in some cases and the retry mechanism in qemu_ram_mmap(). (Michael S. Tsirkin) * Move OS dependent definitions of MAP_SYNC and MAP_SHARED_VALIDATE to osdep.h. (Michael S. Tsirkin) > > 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 >
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