This patch series is ready to be merged via nvdimm tree
as discussed with Dan. We have ack/review on XFS, EXT4
& VIRTIO patches. Device mapper change is also reviewed.
Mike, Can you please provide ack for device mapper change
i.e patch4.
This version has changed implementation for patch 4 as
suggested by 'Mike'. Keeping all the existing r-o-bs. Jakob
CCed also tested the patch series and confirmed the working
of v9.
---
This patch series has implementation for "virtio pmem".
"virtio pmem" is fake persistent memory(nvdimm) in guest
which allows to bypass the guest page cache. This also
implements a VIRTIO based asynchronous flush mechanism.
Sharing guest kernel driver in this patchset with the
changes suggested in v4. Tested with Qemu side device
emulation [5] for virtio-pmem. Documented the impact of
possible page cache side channel attacks with suggested
countermeasures.
Details of project idea for 'virtio pmem' flushing interface
is shared [3] & [4].
Implementation is divided into two parts:
New virtio pmem guest driver and qemu code changes for new
virtio pmem paravirtualized device.
1. Guest virtio-pmem kernel driver
---------------------------------
- Reads persistent memory range from paravirt device and
registers with 'nvdimm_bus'.
- 'nvdimm/pmem' driver uses this information to allocate
persistent memory region and setup filesystem operations
to the allocated memory.
- virtio pmem driver implements asynchronous flushing
interface to flush from guest to host.
2. Qemu virtio-pmem device
---------------------------------
- Creates virtio pmem device and exposes a memory range to
KVM guest.
- At host side this is file backed memory which acts as
persistent memory.
- Qemu side flush uses aio thread pool API's and virtio
for asynchronous guest multi request handling.
Virtio-pmem security implications and countermeasures:
-----------------------------------------------------
In previous posting of kernel driver, there was discussion [7]
on possible implications of page cache side channel attacks with
virtio pmem. After thorough analysis of details of known side
channel attacks, below are the suggestions:
- Depends entirely on how host backing image file is mapped
into guest address space.
- virtio-pmem device emulation, by default shared mapping is used
to map host backing file. It is recommended to use separate
backing file at host side for every guest. This will prevent
any possibility of executing common code from multiple guests
and any chance of inferring guest local data based based on
execution time.
- If backing file is required to be shared among multiple guests
it is recommended to don't support host page cache eviction
commands from the guest driver. This will avoid any possibility
of inferring guest local data or host data from another guest.
- Proposed device specification [6] for virtio-pmem device with
details of possible security implications and suggested
countermeasures for device emulation.
Virtio-pmem errors handling:
----------------------------------------
Checked behaviour of virtio-pmem for below types of errors
Need suggestions on expected behaviour for handling these errors?
- Hardware Errors: Uncorrectable recoverable Errors:
a] virtio-pmem:
- As per current logic if error page belongs to Qemu process,
host MCE handler isolates(hwpoison) that page and send SIGBUS.
Qemu SIGBUS handler injects exception to KVM guest.
- KVM guest then isolates the page and send SIGBUS to guest
userspace process which has mapped the page.
b] Existing implementation for ACPI pmem driver:
- Handles such errors with MCE notifier and creates a list
of bad blocks. Read/direct access DAX operation return EIO
if accessed memory page fall in bad block list.
- It also starts backgound scrubbing.
- Similar functionality can be reused in virtio-pmem with MCE
notifier but without scrubbing(no ACPI/ARS)? Need inputs to
confirm if this behaviour is ok or needs any change?
Changes from PATCH v11: [1]
- Change implmentation for setting of synchronous DAX type
for device mapper - Mike
Changes from PATCH v10: [2]
- Rebased on Linux-5.2-rc4
Changes from PATCH v9:
- Kconfig help text add two spaces - Randy
- Fixed libnvdimm 'bio' include warning - Dan
- virtio-pmem, separate request/resp struct and
move to uapi file with updated license - DavidH
- Use virtio32* type for req/resp endianess - DavidH
- Added tested-by & ack-by of Jakob
- Rebased to 5.2-rc1
Changes from PATCH v8:
- Set device mapper synchronous if all target devices support - Dan
- Move virtio_pmem.h to nvdimm directory - Dan
- Style, indentation & better error messages in patch 2 - DavidH
- Added MST's ack in patch 2.
Changes from PATCH v7:
- Corrected pending request queue logic (patch 2) - Jakub Staroń
- Used unsigned long flags for passing DAXDEV_F_SYNC (patch 3) - Dan
- Fixed typo => vma 'flag' to 'vm_flag' (patch 4)
- Added rob in patch 6 & patch 2
Changes from PATCH v6:
- Corrected comment format in patch 5 & patch 6. [Dave]
- Changed variable declaration indentation in patch 6 [Darrick]
- Add Reviewed-by tag by 'Jan Kara' in patch 4 & patch 5
Changes from PATCH v5:
Changes suggested in by - [Cornelia, Yuval]
- Remove assignment chaining in virtio driver
- Better error message and remove not required free
- Check nd_region before use
Changes suggested by - [Jan Kara]
- dax_synchronous() for !CONFIG_DAX
- Correct 'daxdev_mapping_supported' comment and non-dax implementation
Changes suggested by - [Dan Williams]
- Pass meaningful flag 'DAXDEV_F_SYNC' to alloc_dax
- Gate nvdimm_flush instead of additional async parameter
- Move block chaining logic to flush callback than common nvdimm_flush
- Use NULL flush callback for generic flush for better readability [Dan, Jan]
- Use virtio device id 27 from 25(already used) - [MST]
Changes from PATCH v4:
- Factor out MAP_SYNC supported functionality to a common helper
[Dave, Darrick, Jan]
- Comment, indentation and virtqueue_kick failure handle - Yuval Shaia
Changes from PATCH v3:
- Use generic dax_synchronous() helper to check for DAXDEV_SYNC
flag - [Dan, Darrick, Jan]
- Add 'is_nvdimm_async' function
- Document page cache side channel attacks implications &
countermeasures - [Dave Chinner, Michael]
Changes from PATCH v2:
- Disable MAP_SYNC for ext4 & XFS filesystems - [Dan]
- Use name 'virtio pmem' in place of 'fake dax'
Changes from PATCH v1:
- 0-day build test for build dependency on libnvdimm
Changes suggested by - [Dan Williams]
- Split the driver into two parts virtio & pmem
- Move queuing of async block request to block layer
- Add "sync" parameter in nvdimm_flush function
- Use indirect call for nvdimm_flush
- Don’t move declarations to common global header e.g nd.h
- nvdimm_flush() return 0 or -EIO if it fails
- Teach nsio_rw_bytes() that the flush can fail
- Rename nvdimm_flush() to generic_nvdimm_flush()
- Use 'nd_region->provider_data' for long dereferencing
- Remove virtio_pmem_freeze/restore functions
- Remove BSD license text with SPDX license text
- Add might_sleep() in virtio_pmem_flush - [Luiz]
- Make spin_lock_irqsave() narrow
Pankaj Gupta (7):
libnvdimm: nd_region flush callback support
virtio-pmem: Add virtio-pmem guest driver
libnvdimm: add nd_region buffered dax_dev flag
dax: check synchronous mapping is supported
dm: dm: Enable synchronous dax
ext4: disable map_sync for virtio pmem
xfs: disable map_sync for virtio pmem
[1] https://lkml.org/lkml/2019/6/10/209
[2] https://lkml.org/lkml/2019/5/21/569
[3] https://www.spinics.net/lists/kvm/msg149761.html
[4] https://www.spinics.net/lists/kvm/msg153095.html
[5] https://marc.info/?l=qemu-devel&m=155860751202202&w=2
[6] https://lists.oasis-open.org/archives/virtio-dev/201903/msg00083.html
[7] https://lkml.org/lkml/2019/1/9/1191
drivers/acpi/nfit/core.c | 4 -
drivers/dax/bus.c | 2
drivers/dax/super.c | 19 +++++
drivers/md/dm-table.c | 24 +++++--
drivers/md/dm.c | 5 -
drivers/md/dm.h | 5 +
drivers/nvdimm/Makefile | 1
drivers/nvdimm/claim.c | 6 +
drivers/nvdimm/nd.h | 1
drivers/nvdimm/nd_virtio.c | 124 +++++++++++++++++++++++++++++++++++++++
drivers/nvdimm/pmem.c | 18 +++--
drivers/nvdimm/region_devs.c | 33 +++++++++-
drivers/nvdimm/virtio_pmem.c | 122 ++++++++++++++++++++++++++++++++++++++
drivers/nvdimm/virtio_pmem.h | 55 +++++++++++++++++
drivers/virtio/Kconfig | 11 +++
fs/ext4/file.c | 10 +--
fs/xfs/xfs_file.c | 9 +-
include/linux/dax.h | 26 +++++++-
include/linux/libnvdimm.h | 10 ++-
include/uapi/linux/virtio_ids.h | 1
include/uapi/linux/virtio_pmem.h | 35 +++++++++++
21 files changed, 488 insertions(+), 33 deletions(-)
This patch adds 'DAXDEV_SYNC' flag which is set
for nd_region doing synchronous flush. This later
is used to disable MAP_SYNC functionality for
ext4 & xfs filesystem for devices don't support
synchronous flush.
Signed-off-by: Pankaj Gupta <[email protected]>
---
drivers/dax/bus.c | 2 +-
drivers/dax/super.c | 19 ++++++++++++++++++-
drivers/md/dm.c | 3 ++-
drivers/nvdimm/pmem.c | 5 ++++-
drivers/nvdimm/region_devs.c | 7 +++++++
include/linux/dax.h | 9 +++++++--
include/linux/libnvdimm.h | 1 +
7 files changed, 40 insertions(+), 6 deletions(-)
diff --git a/drivers/dax/bus.c b/drivers/dax/bus.c
index 2109cfe80219..5f184e751c82 100644
--- a/drivers/dax/bus.c
+++ b/drivers/dax/bus.c
@@ -388,7 +388,7 @@ struct dev_dax *__devm_create_dev_dax(struct dax_region *dax_region, int id,
* No 'host' or dax_operations since there is no access to this
* device outside of mmap of the resulting character device.
*/
- dax_dev = alloc_dax(dev_dax, NULL, NULL);
+ dax_dev = alloc_dax(dev_dax, NULL, NULL, DAXDEV_F_SYNC);
if (!dax_dev)
goto err;
diff --git a/drivers/dax/super.c b/drivers/dax/super.c
index bbd57ca0634a..93b3718b5cfa 100644
--- a/drivers/dax/super.c
+++ b/drivers/dax/super.c
@@ -186,6 +186,8 @@ enum dax_device_flags {
DAXDEV_ALIVE,
/* gate whether dax_flush() calls the low level flush routine */
DAXDEV_WRITE_CACHE,
+ /* flag to check if device supports synchronous flush */
+ DAXDEV_SYNC,
};
/**
@@ -354,6 +356,18 @@ bool dax_write_cache_enabled(struct dax_device *dax_dev)
}
EXPORT_SYMBOL_GPL(dax_write_cache_enabled);
+bool dax_synchronous(struct dax_device *dax_dev)
+{
+ return test_bit(DAXDEV_SYNC, &dax_dev->flags);
+}
+EXPORT_SYMBOL_GPL(dax_synchronous);
+
+void set_dax_synchronous(struct dax_device *dax_dev)
+{
+ set_bit(DAXDEV_SYNC, &dax_dev->flags);
+}
+EXPORT_SYMBOL_GPL(set_dax_synchronous);
+
bool dax_alive(struct dax_device *dax_dev)
{
lockdep_assert_held(&dax_srcu);
@@ -508,7 +522,7 @@ static void dax_add_host(struct dax_device *dax_dev, const char *host)
}
struct dax_device *alloc_dax(void *private, const char *__host,
- const struct dax_operations *ops)
+ const struct dax_operations *ops, unsigned long flags)
{
struct dax_device *dax_dev;
const char *host;
@@ -531,6 +545,9 @@ struct dax_device *alloc_dax(void *private, const char *__host,
dax_add_host(dax_dev, host);
dax_dev->ops = ops;
dax_dev->private = private;
+ if (flags & DAXDEV_F_SYNC)
+ set_dax_synchronous(dax_dev);
+
return dax_dev;
err_dev:
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 1fb1333fefec..7eee7ddc73a8 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -1970,7 +1970,8 @@ static struct mapped_device *alloc_dev(int minor)
sprintf(md->disk->disk_name, "dm-%d", minor);
if (IS_ENABLED(CONFIG_DAX_DRIVER)) {
- md->dax_dev = alloc_dax(md, md->disk->disk_name, &dm_dax_ops);
+ md->dax_dev = alloc_dax(md, md->disk->disk_name,
+ &dm_dax_ops, 0);
if (!md->dax_dev)
goto bad;
}
diff --git a/drivers/nvdimm/pmem.c b/drivers/nvdimm/pmem.c
index 0279eb1da3ef..bdbd2b414d3d 100644
--- a/drivers/nvdimm/pmem.c
+++ b/drivers/nvdimm/pmem.c
@@ -365,6 +365,7 @@ static int pmem_attach_disk(struct device *dev,
struct gendisk *disk;
void *addr;
int rc;
+ unsigned long flags = 0UL;
pmem = devm_kzalloc(dev, sizeof(*pmem), GFP_KERNEL);
if (!pmem)
@@ -462,7 +463,9 @@ static int pmem_attach_disk(struct device *dev,
nvdimm_badblocks_populate(nd_region, &pmem->bb, &bb_res);
disk->bb = &pmem->bb;
- dax_dev = alloc_dax(pmem, disk->disk_name, &pmem_dax_ops);
+ if (is_nvdimm_sync(nd_region))
+ flags = DAXDEV_F_SYNC;
+ dax_dev = alloc_dax(pmem, disk->disk_name, &pmem_dax_ops, flags);
if (!dax_dev) {
put_disk(disk);
return -ENOMEM;
diff --git a/drivers/nvdimm/region_devs.c b/drivers/nvdimm/region_devs.c
index b4ef7d9ff22e..f3ea5369d20a 100644
--- a/drivers/nvdimm/region_devs.c
+++ b/drivers/nvdimm/region_devs.c
@@ -1197,6 +1197,13 @@ int nvdimm_has_cache(struct nd_region *nd_region)
}
EXPORT_SYMBOL_GPL(nvdimm_has_cache);
+bool is_nvdimm_sync(struct nd_region *nd_region)
+{
+ return is_nd_pmem(&nd_region->dev) &&
+ !test_bit(ND_REGION_ASYNC, &nd_region->flags);
+}
+EXPORT_SYMBOL_GPL(is_nvdimm_sync);
+
struct conflict_context {
struct nd_region *nd_region;
resource_size_t start, size;
diff --git a/include/linux/dax.h b/include/linux/dax.h
index 0dd316a74a29..2b106752b1b8 100644
--- a/include/linux/dax.h
+++ b/include/linux/dax.h
@@ -7,6 +7,9 @@
#include <linux/radix-tree.h>
#include <asm/pgtable.h>
+/* Flag for synchronous flush */
+#define DAXDEV_F_SYNC (1UL << 0)
+
typedef unsigned long dax_entry_t;
struct iomap_ops;
@@ -32,18 +35,20 @@ extern struct attribute_group dax_attribute_group;
#if IS_ENABLED(CONFIG_DAX)
struct dax_device *dax_get_by_host(const char *host);
struct dax_device *alloc_dax(void *private, const char *host,
- const struct dax_operations *ops);
+ const struct dax_operations *ops, unsigned long flags);
void put_dax(struct dax_device *dax_dev);
void kill_dax(struct dax_device *dax_dev);
void dax_write_cache(struct dax_device *dax_dev, bool wc);
bool dax_write_cache_enabled(struct dax_device *dax_dev);
+bool dax_synchronous(struct dax_device *dax_dev);
+void set_dax_synchronous(struct dax_device *dax_dev);
#else
static inline struct dax_device *dax_get_by_host(const char *host)
{
return NULL;
}
static inline struct dax_device *alloc_dax(void *private, const char *host,
- const struct dax_operations *ops)
+ const struct dax_operations *ops, unsigned long flags)
{
/*
* Callers should check IS_ENABLED(CONFIG_DAX) to know if this
diff --git a/include/linux/libnvdimm.h b/include/linux/libnvdimm.h
index feb342d026f2..3238a206e563 100644
--- a/include/linux/libnvdimm.h
+++ b/include/linux/libnvdimm.h
@@ -264,6 +264,7 @@ void nvdimm_flush(struct nd_region *nd_region);
int nvdimm_has_flush(struct nd_region *nd_region);
int nvdimm_has_cache(struct nd_region *nd_region);
int nvdimm_in_overwrite(struct nvdimm *nvdimm);
+bool is_nvdimm_sync(struct nd_region *nd_region);
static inline int nvdimm_ctl(struct nvdimm *nvdimm, unsigned int cmd, void *buf,
unsigned int buf_len, int *cmd_rc)
--
2.20.1
This patch sets dax device 'DAXDEV_SYNC' flag if all the target
devices of device mapper support synchrononous DAX. If device
mapper consists of both synchronous and asynchronous dax devices,
we don't set 'DAXDEV_SYNC' flag.
'dm_table_supports_dax' is refactored to pass 'iterate_devices_fn'
as argument so that the callers can pass the appropriate functions.
Suggested-by: Mike Snitzer <[email protected]>
Signed-off-by: Pankaj Gupta <[email protected]>
---
drivers/md/dm-table.c | 24 ++++++++++++++++++------
drivers/md/dm.c | 2 +-
drivers/md/dm.h | 5 ++++-
3 files changed, 23 insertions(+), 8 deletions(-)
diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c
index 350cf0451456..81c55304c4fa 100644
--- a/drivers/md/dm-table.c
+++ b/drivers/md/dm-table.c
@@ -881,7 +881,7 @@ void dm_table_set_type(struct dm_table *t, enum dm_queue_mode type)
EXPORT_SYMBOL_GPL(dm_table_set_type);
/* validate the dax capability of the target device span */
-static int device_supports_dax(struct dm_target *ti, struct dm_dev *dev,
+int device_supports_dax(struct dm_target *ti, struct dm_dev *dev,
sector_t start, sector_t len, void *data)
{
int blocksize = *(int *) data;
@@ -890,7 +890,15 @@ static int device_supports_dax(struct dm_target *ti, struct dm_dev *dev,
start, len);
}
-bool dm_table_supports_dax(struct dm_table *t, int blocksize)
+/* Check devices support synchronous DAX */
+static int device_synchronous(struct dm_target *ti, struct dm_dev *dev,
+ sector_t start, sector_t len, void *data)
+{
+ return dax_synchronous(dev->dax_dev);
+}
+
+bool dm_table_supports_dax(struct dm_table *t,
+ iterate_devices_callout_fn iterate_fn, int *blocksize)
{
struct dm_target *ti;
unsigned i;
@@ -903,8 +911,7 @@ bool dm_table_supports_dax(struct dm_table *t, int blocksize)
return false;
if (!ti->type->iterate_devices ||
- !ti->type->iterate_devices(ti, device_supports_dax,
- &blocksize))
+ !ti->type->iterate_devices(ti, iterate_fn, blocksize))
return false;
}
@@ -940,6 +947,7 @@ static int dm_table_determine_type(struct dm_table *t)
struct dm_target *tgt;
struct list_head *devices = dm_table_get_devices(t);
enum dm_queue_mode live_md_type = dm_get_md_type(t->md);
+ int page_size = PAGE_SIZE;
if (t->type != DM_TYPE_NONE) {
/* target already set the table's type */
@@ -984,7 +992,7 @@ static int dm_table_determine_type(struct dm_table *t)
verify_bio_based:
/* We must use this table as bio-based */
t->type = DM_TYPE_BIO_BASED;
- if (dm_table_supports_dax(t, PAGE_SIZE) ||
+ if (dm_table_supports_dax(t, device_supports_dax, &page_size) ||
(list_empty(devices) && live_md_type == DM_TYPE_DAX_BIO_BASED)) {
t->type = DM_TYPE_DAX_BIO_BASED;
} else {
@@ -1883,6 +1891,7 @@ void dm_table_set_restrictions(struct dm_table *t, struct request_queue *q,
struct queue_limits *limits)
{
bool wc = false, fua = false;
+ int page_size = PAGE_SIZE;
/*
* Copy table's limits to the DM device's request_queue
@@ -1910,8 +1919,11 @@ void dm_table_set_restrictions(struct dm_table *t, struct request_queue *q,
}
blk_queue_write_cache(q, wc, fua);
- if (dm_table_supports_dax(t, PAGE_SIZE))
+ if (dm_table_supports_dax(t, device_supports_dax, &page_size)) {
blk_queue_flag_set(QUEUE_FLAG_DAX, q);
+ if (dm_table_supports_dax(t, device_synchronous, NULL))
+ set_dax_synchronous(t->md->dax_dev);
+ }
else
blk_queue_flag_clear(QUEUE_FLAG_DAX, q);
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index b1caa7188209..b92c42a72ad4 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -1119,7 +1119,7 @@ static bool dm_dax_supported(struct dax_device *dax_dev, struct block_device *bd
if (!map)
return false;
- ret = dm_table_supports_dax(map, blocksize);
+ ret = dm_table_supports_dax(map, device_supports_dax, &blocksize);
dm_put_live_table(md, srcu_idx);
diff --git a/drivers/md/dm.h b/drivers/md/dm.h
index 17e3db54404c..0475673337f3 100644
--- a/drivers/md/dm.h
+++ b/drivers/md/dm.h
@@ -72,7 +72,10 @@ bool dm_table_bio_based(struct dm_table *t);
bool dm_table_request_based(struct dm_table *t);
void dm_table_free_md_mempools(struct dm_table *t);
struct dm_md_mempools *dm_table_get_md_mempools(struct dm_table *t);
-bool dm_table_supports_dax(struct dm_table *t, int blocksize);
+bool dm_table_supports_dax(struct dm_table *t, iterate_devices_callout_fn fn,
+ int *blocksize);
+int device_supports_dax(struct dm_target *ti, struct dm_dev *dev,
+ sector_t start, sector_t len, void *data);
void dm_lock_md_type(struct mapped_device *md);
void dm_unlock_md_type(struct mapped_device *md);
--
2.20.1
This patch introduces 'daxdev_mapping_supported' helper
which checks if 'MAP_SYNC' is supported with filesystem
mapping. It also checks if corresponding dax_device is
synchronous. Virtio pmem device is asynchronous and
does not not support VM_SYNC.
Suggested-by: Jan Kara <[email protected]>
Signed-off-by: Pankaj Gupta <[email protected]>
Reviewed-by: Jan Kara <[email protected]>
---
include/linux/dax.h | 17 +++++++++++++++++
1 file changed, 17 insertions(+)
diff --git a/include/linux/dax.h b/include/linux/dax.h
index 2b106752b1b8..267251a394fa 100644
--- a/include/linux/dax.h
+++ b/include/linux/dax.h
@@ -42,6 +42,18 @@ void dax_write_cache(struct dax_device *dax_dev, bool wc);
bool dax_write_cache_enabled(struct dax_device *dax_dev);
bool dax_synchronous(struct dax_device *dax_dev);
void set_dax_synchronous(struct dax_device *dax_dev);
+/*
+ * Check if given mapping is supported by the file / underlying device.
+ */
+static inline bool daxdev_mapping_supported(struct vm_area_struct *vma,
+ struct dax_device *dax_dev)
+{
+ if (!(vma->vm_flags & VM_SYNC))
+ return true;
+ if (!IS_DAX(file_inode(vma->vm_file)))
+ return false;
+ return dax_synchronous(dax_dev);
+}
#else
static inline struct dax_device *dax_get_by_host(const char *host)
{
@@ -69,6 +81,11 @@ static inline bool dax_write_cache_enabled(struct dax_device *dax_dev)
{
return false;
}
+static inline bool daxdev_mapping_supported(struct vm_area_struct *vma,
+ struct dax_device *dax_dev)
+{
+ return !(vma->vm_flags & VM_SYNC);
+}
#endif
struct writeback_control;
--
2.20.1
Dont support 'MAP_SYNC' with non-DAX files and DAX files
with asynchronous dax_device. Virtio pmem provides
asynchronous host page cache flush mechanism. We don't
support 'MAP_SYNC' with virtio pmem and ext4.
Signed-off-by: Pankaj Gupta <[email protected]>
Reviewed-by: Jan Kara <[email protected]>
---
fs/ext4/file.c | 10 ++++++----
1 file changed, 6 insertions(+), 4 deletions(-)
diff --git a/fs/ext4/file.c b/fs/ext4/file.c
index 98ec11f69cd4..dee549339e13 100644
--- a/fs/ext4/file.c
+++ b/fs/ext4/file.c
@@ -360,15 +360,17 @@ static const struct vm_operations_struct ext4_file_vm_ops = {
static int ext4_file_mmap(struct file *file, struct vm_area_struct *vma)
{
struct inode *inode = file->f_mapping->host;
+ struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
+ struct dax_device *dax_dev = sbi->s_daxdev;
- if (unlikely(ext4_forced_shutdown(EXT4_SB(inode->i_sb))))
+ if (unlikely(ext4_forced_shutdown(sbi)))
return -EIO;
/*
- * We don't support synchronous mappings for non-DAX files. At least
- * until someone comes with a sensible use case.
+ * We don't support synchronous mappings for non-DAX files and
+ * for DAX files if underneath dax_device is not synchronous.
*/
- if (!IS_DAX(file_inode(file)) && (vma->vm_flags & VM_SYNC))
+ if (!daxdev_mapping_supported(vma, dax_dev))
return -EOPNOTSUPP;
file_accessed(file);
--
2.20.1
Dont support 'MAP_SYNC' with non-DAX files and DAX files
with asynchronous dax_device. Virtio pmem provides
asynchronous host page cache flush mechanism. We don't
support 'MAP_SYNC' with virtio pmem and xfs.
Signed-off-by: Pankaj Gupta <[email protected]>
Reviewed-by: Darrick J. Wong <[email protected]>
---
fs/xfs/xfs_file.c | 9 ++++++---
1 file changed, 6 insertions(+), 3 deletions(-)
diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
index a7ceae90110e..f17652cca5ff 100644
--- a/fs/xfs/xfs_file.c
+++ b/fs/xfs/xfs_file.c
@@ -1203,11 +1203,14 @@ xfs_file_mmap(
struct file *filp,
struct vm_area_struct *vma)
{
+ struct dax_device *dax_dev;
+
+ dax_dev = xfs_find_daxdev_for_inode(file_inode(filp));
/*
- * We don't support synchronous mappings for non-DAX files. At least
- * until someone comes with a sensible use case.
+ * We don't support synchronous mappings for non-DAX files and
+ * for DAX files if underneath dax_device is not synchronous.
*/
- if (!IS_DAX(file_inode(filp)) && (vma->vm_flags & VM_SYNC))
+ if (!daxdev_mapping_supported(vma, dax_dev))
return -EOPNOTSUPP;
file_accessed(filp);
--
2.20.1