| Message ID | cover.1544598069.git.yi.z.zhang@linux.intel.com (mailing list archive) |
|---|---|
| Headers | show |
| Series | nvdimm: support MAP_SYNC for memory-backend-file | expand |
On Wed, Dec 12, 2018 at 04:11:44PM +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' Can this change be limited to a real DAX device? Then you won't need to bother with flags at all. And am I mistaken in thinking that this will affect all guest memory with share=on? Or do I misunderstand? > Changes in v6: > * Pankaj: 3/7 are squashed with 2/7 > * Pankaj: 7/7 update comments to "consistent filesystem metadata". > * Pankaj, Igor: 1/7 Added Reviewed-by in patch-1/7 > * Stefan, 4/7 move the include header from "/linux/mman.h" to "osdep.h" > * Stefan, 5/7 Add missing "munmap" > * Stefan, 2/7 refine the shared/flag. > > 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 (6): > numa: Fixed the memory leak of numa error message > util/mmap-alloc: switch qemu_ram_mmap() to '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/qemu/osdep.h | 29 +++++++++++++++++++++++++++++ > numa.c | 1 + > qemu-options.hx | 22 +++++++++++++++++++++- > util/mmap-alloc.c | 26 +++++++++++++++++++++----- > util/oslib-posix.c | 8 +++++++- > 12 files changed, 189 insertions(+), 18 deletions(-) > > -- > 2.7.4
On 2018-12-12 at 10:06:13 -0500, Michael S. Tsirkin wrote: > On Wed, Dec 12, 2018 at 04:11:44PM +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' > > Can this change be limited to a real DAX device? > Then you won't need to bother with flags at all. Thanks Micheal's review, For real dax device, we still need to have a option to turn sync off. > > And am I mistaken in thinking that this will affect all > guest memory with share=on? Or do I misunderstand? Only file-backend memory with share=on. > > > > > Changes in v6: > > * Pankaj: 3/7 are squashed with 2/7 > > * Pankaj: 7/7 update comments to "consistent filesystem metadata". > > * Pankaj, Igor: 1/7 Added Reviewed-by in patch-1/7 > > * Stefan, 4/7 move the include header from "/linux/mman.h" to "osdep.h" > > * Stefan, 5/7 Add missing "munmap" > > * Stefan, 2/7 refine the shared/flag. > > > > 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 (6): > > numa: Fixed the memory leak of numa error message > > util/mmap-alloc: switch qemu_ram_mmap() to '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/qemu/osdep.h | 29 +++++++++++++++++++++++++++++ > > numa.c | 1 + > > qemu-options.hx | 22 +++++++++++++++++++++- > > util/mmap-alloc.c | 26 +++++++++++++++++++++----- > > util/oslib-posix.c | 8 +++++++- > > 12 files changed, 189 insertions(+), 18 deletions(-) > > > > -- > > 2.7.4
On Wed, Dec 12, 2018 at 04:11:44PM +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 v6: > * Pankaj: 3/7 are squashed with 2/7 > * Pankaj: 7/7 update comments to "consistent filesystem metadata". > * Pankaj, Igor: 1/7 Added Reviewed-by in patch-1/7 > * Stefan, 4/7 move the include header from "/linux/mman.h" to "osdep.h" > * Stefan, 5/7 Add missing "munmap" > * Stefan, 2/7 refine the shared/flag. > > 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 (6): > numa: Fixed the memory leak of numa error message > util/mmap-alloc: switch qemu_ram_mmap() to '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/qemu/osdep.h | 29 +++++++++++++++++++++++++++++ > numa.c | 1 + > qemu-options.hx | 22 +++++++++++++++++++++- > util/mmap-alloc.c | 26 +++++++++++++++++++++----- > util/oslib-posix.c | 8 +++++++- > 12 files changed, 189 insertions(+), 18 deletions(-) > > -- > 2.7.4 > Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
On Mon, Dec 17, 2018 at 01:53:54PM +0800, Yi Zhang wrote: > On 2018-12-12 at 10:06:13 -0500, Michael S. Tsirkin wrote: > > On Wed, Dec 12, 2018 at 04:11:44PM +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' > > > > Can this change be limited to a real DAX device? > > Then you won't need to bother with flags at all. > Thanks Micheal's review, > > For real dax device, we still need to have a option to turn sync off. Not sure why really. Why use an nvdimm if you don't actually want it to be persistent? > > > > And am I mistaken in thinking that this will affect all > > guest memory with share=on? Or do I misunderstand? > > Only file-backend memory with share=on. Yes but that's everyone if e.g. vhost-user needs to be active. So frankly I don't think it's a good idea to change the default like this unless it's limited to nvdimm in some way. > > > > > > > > > Changes in v6: > > > * Pankaj: 3/7 are squashed with 2/7 > > > * Pankaj: 7/7 update comments to "consistent filesystem metadata". > > > * Pankaj, Igor: 1/7 Added Reviewed-by in patch-1/7 > > > * Stefan, 4/7 move the include header from "/linux/mman.h" to "osdep.h" > > > * Stefan, 5/7 Add missing "munmap" > > > * Stefan, 2/7 refine the shared/flag. > > > > > > 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 (6): > > > numa: Fixed the memory leak of numa error message > > > util/mmap-alloc: switch qemu_ram_mmap() to '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/qemu/osdep.h | 29 +++++++++++++++++++++++++++++ > > > numa.c | 1 + > > > qemu-options.hx | 22 +++++++++++++++++++++- > > > util/mmap-alloc.c | 26 +++++++++++++++++++++----- > > > util/oslib-posix.c | 8 +++++++- > > > 12 files changed, 189 insertions(+), 18 deletions(-) > > > > > > -- > > > 2.7.4
On 2018-12-17 at 10:27:50 -0500, Michael S. Tsirkin wrote: > On Mon, Dec 17, 2018 at 01:53:54PM +0800, Yi Zhang wrote: > > On 2018-12-12 at 10:06:13 -0500, Michael S. Tsirkin wrote: > > > On Wed, Dec 12, 2018 at 04:11:44PM +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' > > > > > > Can this change be limited to a real DAX device? > > > Then you won't need to bother with flags at all. > > Thanks Micheal's review, > > > > For real dax device, we still need to have a option to turn sync off. > > Not sure why really. Why use an nvdimm if you don't actually > want it to be persistent? > > > > > > > > And am I mistaken in thinking that this will affect all > > > guest memory with share=on? Or do I misunderstand? > > > > Only file-backend memory with share=on. > > Yes but that's everyone if e.g. vhost-user needs to be active. > > So frankly I don't think it's a good idea to change the default like this > unless it's limited to nvdimm in some way. Yes, fine, I will limit this flag only on an nvdimm backend. Thanks, Micheal. > > > > > > > > > > > > > > Changes in v6: > > > > * Pankaj: 3/7 are squashed with 2/7 > > > > * Pankaj: 7/7 update comments to "consistent filesystem metadata". > > > > * Pankaj, Igor: 1/7 Added Reviewed-by in patch-1/7 > > > > * Stefan, 4/7 move the include header from "/linux/mman.h" to "osdep.h" > > > > * Stefan, 5/7 Add missing "munmap" > > > > * Stefan, 2/7 refine the shared/flag. > > > > > > > > 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 (6): > > > > numa: Fixed the memory leak of numa error message > > > > util/mmap-alloc: switch qemu_ram_mmap() to '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/qemu/osdep.h | 29 +++++++++++++++++++++++++++++ > > > > numa.c | 1 + > > > > qemu-options.hx | 22 +++++++++++++++++++++- > > > > util/mmap-alloc.c | 26 +++++++++++++++++++++----- > > > > util/oslib-posix.c | 8 +++++++- > > > > 12 files changed, 189 insertions(+), 18 deletions(-) > > > > > > > > -- > > > > 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' Changes in v6: * Pankaj: 3/7 are squashed with 2/7 * Pankaj: 7/7 update comments to "consistent filesystem metadata". * Pankaj, Igor: 1/7 Added Reviewed-by in patch-1/7 * Stefan, 4/7 move the include header from "/linux/mman.h" to "osdep.h" * Stefan, 5/7 Add missing "munmap" * Stefan, 2/7 refine the shared/flag. 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 (6): numa: Fixed the memory leak of numa error message util/mmap-alloc: switch qemu_ram_mmap() to '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/qemu/osdep.h | 29 +++++++++++++++++++++++++++++ numa.c | 1 + qemu-options.hx | 22 +++++++++++++++++++++- util/mmap-alloc.c | 26 +++++++++++++++++++++----- util/oslib-posix.c | 8 +++++++- 12 files changed, 189 insertions(+), 18 deletions(-)