linux-toradex.git/drivers/dax/fsdev.c, branch master Linux kernel for Apalis and Colibri modules dax/fsdev: fix uninitialized kaddr in fsdev_dax_zero_page_range() 2026-04-13T19:15:15+00:00 John Groves John@Groves.net 2026-04-12T15:50:06+00:00 45df9111692c62d5f09fc4345ae36dae31024797 __fsdev_dax_direct_access() returns -EFAULT without setting *kaddr when dax_pgoff_to_phys() returns -1 (pgoff out of range). The return value was ignored, leaving kaddr uninitialized before being passed to fsdev_write_dax(). Check the return value and propagate the error. Thanks to Dan Carpenter and the smatch project for reporting this. Signed-off-by: John Groves <john@groves.net> Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com> Reviewed-by: Dave Jiang <dave.jiang@intel.com> Link: https://patch.msgid.link/0100019d8262cda2-9714d31c-8fc1-4ca5-b32d-4df678240d14-000000@email.amazonses.com Signed-off-by: Ira Weiny <ira.weiny@intel.com> 
__fsdev_dax_direct_access() returns -EFAULT without setting *kaddr when
dax_pgoff_to_phys() returns -1 (pgoff out of range). The return value
was ignored, leaving kaddr uninitialized before being passed to
fsdev_write_dax().

Check the return value and propagate the error.

Thanks to Dan Carpenter and the smatch project for reporting this.

Signed-off-by: John Groves <john@groves.net>
Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com>
Reviewed-by: Dave Jiang <dave.jiang@intel.com>
Link: https://patch.msgid.link/0100019d8262cda2-9714d31c-8fc1-4ca5-b32d-4df678240d14-000000@email.amazonses.com
Signed-off-by: Ira Weiny <ira.weiny@intel.com>
dax: Add dax_set_ops() for setting dax_operations at bind time 2026-03-30T13:20:48+00:00 John Groves John@Groves.net 2026-03-27T21:05:03+00:00 700ecbc1f5aa02ba9ad68d7be1ef7a9c8eae07e9 Add a new dax_set_ops() function that allows drivers to set the dax_operations after the dax_device has been allocated. This is needed for fsdev_dax where the operations need to be set during probe and cleared during unbind. The fsdev driver uses devm_add_action_or_reset() for cleanup consistency, avoiding the complexity of mixing devm-managed resources with manual cleanup in a remove() callback. This ensures cleanup happens automatically in the correct reverse order when the device is unbound. Reviewed-by: Dave Jiang <dave.jiang@intel.com> Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com> Signed-off-by: John Groves <john@groves.net> Link: https://patch.msgid.link/0100019d311d65a0-b9c1419e-f3a0-4afd-b0bd-848f18ff5950-000000@email.amazonses.com Signed-off-by: Ira Weiny <ira.weiny@intel.com> 
Add a new dax_set_ops() function that allows drivers to set the
dax_operations after the dax_device has been allocated. This is needed
for fsdev_dax where the operations need to be set during probe and
cleared during unbind.

The fsdev driver uses devm_add_action_or_reset() for cleanup consistency,
avoiding the complexity of mixing devm-managed resources with manual
cleanup in a remove() callback. This ensures cleanup happens automatically
in the correct reverse order when the device is unbound.

Reviewed-by: Dave Jiang <dave.jiang@intel.com>
Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com>
Signed-off-by: John Groves <john@groves.net>
Link: https://patch.msgid.link/0100019d311d65a0-b9c1419e-f3a0-4afd-b0bd-848f18ff5950-000000@email.amazonses.com
Signed-off-by: Ira Weiny <ira.weiny@intel.com>
dax: Add dax_operations for use by fs-dax on fsdev dax 2026-03-30T13:20:48+00:00 John Groves John@Groves.net 2026-03-27T21:04:54+00:00 099c81a1f0ab3e948d73c5ab2b7a3b702af36e64 fsdev: Add dax_operations for use by famfs. This replicates the functionality from drivers/nvdimm/pmem.c that conventional fs-dax file systems (e.g. xfs) use to support dax read/write/mmap to a daxdev - without which famfs can't sit atop a daxdev. - These methods are based on pmem_dax_ops from drivers/nvdimm/pmem.c - fsdev_dax_direct_access() returns the hpa, pfn and kva. The kva was newly stored as dev_dax->virt_addr by dev_dax_probe(). - The hpa/pfn are used for mmap (dax_iomap_fault()), and the kva is used for read/write (dax_iomap_rw()) - fsdev_dax_recovery_write() and dev_dax_zero_page_range() have not been tested yet. I'm looking for suggestions as to how to test those. - dax-private.h: add dev_dax->cached_size, which fsdev needs to remember. The dev_dax size cannot change while a driver is bound (dev_dax_resize returns -EBUSY if dev->driver is set). Caching the size at probe time allows fsdev's direct_access path can use it without acquiring dax_dev_rwsem (which isn't exported anyway). Signed-off-by: John Groves <john@groves.net> Link: https://patch.msgid.link/0100019d311d415a-bd6af0fe-5445-484c-9d39-210b8170b686-000000@email.amazonses.com Signed-off-by: Ira Weiny <ira.weiny@intel.com> 
fsdev: Add dax_operations for use by famfs.

This replicates the functionality from drivers/nvdimm/pmem.c that
conventional fs-dax file systems (e.g. xfs) use to support dax
read/write/mmap to a daxdev - without which famfs can't sit atop a
daxdev.

- These methods are based on pmem_dax_ops from drivers/nvdimm/pmem.c
- fsdev_dax_direct_access() returns the hpa, pfn and kva. The kva was
  newly stored as dev_dax->virt_addr by dev_dax_probe().
- The hpa/pfn are used for mmap (dax_iomap_fault()), and the kva is used
  for read/write (dax_iomap_rw())
- fsdev_dax_recovery_write() and dev_dax_zero_page_range() have not been
  tested yet. I'm looking for suggestions as to how to test those.
- dax-private.h: add dev_dax->cached_size, which fsdev needs to
  remember. The dev_dax size cannot change while a driver is bound
  (dev_dax_resize returns -EBUSY if dev->driver is set). Caching the size
  at probe time allows fsdev's direct_access path can use it without
  acquiring dax_dev_rwsem (which isn't exported anyway).

Signed-off-by: John Groves <john@groves.net>
Link: https://patch.msgid.link/0100019d311d415a-bd6af0fe-5445-484c-9d39-210b8170b686-000000@email.amazonses.com
Signed-off-by: Ira Weiny <ira.weiny@intel.com>
dax: Save the kva from memremap 2026-03-30T13:20:47+00:00 John Groves john@groves.net 2026-03-27T21:04:44+00:00 759455848df0b9ac3acabdbedcdc4a55af67935f Save the kva from memremap because we need it for iomap rw support. Prior to famfs, there were no iomap users of /dev/dax - so the virtual address from memremap was not needed. Reviewed-by: Ira Weiny <ira.weiny@intel.com> Reviewed-by: Dave Jiang <dave.jiang@intel.com> Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com> Signed-off-by: John Groves <john@groves.net> Link: https://patch.msgid.link/0100019d311d1d08-dd372cb9-5934-43b8-bef8-089660d04a81-000000@email.amazonses.com Signed-off-by: Ira Weiny <ira.weiny@intel.com> 
Save the kva from memremap because we need it for iomap rw support.

Prior to famfs, there were no iomap users of /dev/dax - so the virtual
address from memremap was not needed.

Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Reviewed-by: Dave Jiang <dave.jiang@intel.com>
Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com>
Signed-off-by: John Groves <john@groves.net>
Link: https://patch.msgid.link/0100019d311d1d08-dd372cb9-5934-43b8-bef8-089660d04a81-000000@email.amazonses.com
Signed-off-by: Ira Weiny <ira.weiny@intel.com>
dax: add fsdev.c driver for fs-dax on character dax 2026-03-30T13:20:47+00:00 John Groves john@groves.net 2026-03-27T21:04:35+00:00 d5406bd458b0ac10b1301a4d5801d85c8f648637 The new fsdev driver provides pages/folios initialized compatibly with fsdax - normal rather than devdax-style refcounting, and starting out with order-0 folios. When fsdev binds to a daxdev, it is usually (always?) switching from the devdax mode (device.c), which pre-initializes compound folios according to its alignment. Fsdev uses fsdev_clear_folio_state() to switch the folios into a fsdax-compatible state. A side effect of this is that raw mmap doesn't (can't?) work on an fsdev dax instance. Accordingly, The fsdev driver does not provide raw mmap - devices must be put in 'devdax' mode (drivers/dax/device.c) to get raw mmap capability. In this commit is just the framework, which remaps pages/folios compatibly with fsdax. Enabling dax changes: - bus.h: add DAXDRV_FSDEV_TYPE driver type - bus.c: allow DAXDRV_FSDEV_TYPE drivers to bind to daxdevs - dax.h: prototype inode_dax(), which fsdev needs Suggested-by: Dan Williams <dan.j.williams@intel.com> Suggested-by: Gregory Price <gourry@gourry.net> Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com> Signed-off-by: John Groves <john@groves.net> Link: https://patch.msgid.link/0100019d311cf904-419e9526-bdaf-4daa-97f1-5060b31a5c9f-000000@email.amazonses.com Signed-off-by: Ira Weiny <ira.weiny@intel.com> 
The new fsdev driver provides pages/folios initialized compatibly with
fsdax - normal rather than devdax-style refcounting, and starting out
with order-0 folios.

When fsdev binds to a daxdev, it is usually (always?) switching from the
devdax mode (device.c), which pre-initializes compound folios according
to its alignment. Fsdev uses fsdev_clear_folio_state() to switch the
folios into a fsdax-compatible state.

A side effect of this is that raw mmap doesn't (can't?) work on an fsdev
dax instance. Accordingly, The fsdev driver does not provide raw mmap -
devices must be put in 'devdax' mode (drivers/dax/device.c) to get raw
mmap capability.

In this commit is just the framework, which remaps pages/folios compatibly
with fsdax.

Enabling dax changes:

- bus.h: add DAXDRV_FSDEV_TYPE driver type
- bus.c: allow DAXDRV_FSDEV_TYPE drivers to bind to daxdevs
- dax.h: prototype inode_dax(), which fsdev needs

Suggested-by: Dan Williams <dan.j.williams@intel.com>
Suggested-by: Gregory Price <gourry@gourry.net>
Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com>
Signed-off-by: John Groves <john@groves.net>
Link: https://patch.msgid.link/0100019d311cf904-419e9526-bdaf-4daa-97f1-5060b31a5c9f-000000@email.amazonses.com
Signed-off-by: Ira Weiny <ira.weiny@intel.com>