[PATCH v3 02/13] device/dax: update devdax to use mmap_prepare

Lorenzo Stoakes
2025-09-16T14:14:44Z

The devdax driver does nothing special in its f_op->mmap hook, so
straightforwardly update it to use the mmap_prepare hook instead.

Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Acked-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Jan Kara <jack@suse.cz>
---
drivers/dax/device.c | 32 +++++++++++++++++++++-----------
1 file changed, 21 insertions(+), 11 deletions(-)

diff --git a/drivers/dax/device.c b/drivers/dax/device.c
index 2bb40a6060af..c2181439f925 100644
--- a/drivers/dax/device.c
+++ b/drivers/dax/device.c
@@ -13,8 +13,9 @@
#include "dax-private.h"
#include "bus.h"

-static int check_vma(struct dev_dax *dev_dax, struct vm_area_struct *vma,
- const char *func)
+static int __check_vma(struct dev_dax *dev_dax, vm_flags_t vm_flags,
+ unsigned long start, unsigned long end, struct file *file,
+ const char *func)
{
struct device *dev = &dev_dax->dev;
unsigned long mask;
@@ -23,7 +24,7 @@ static int check_vma(struct dev_dax *dev_dax, struct vm_area_struct *vma,
return -ENXIO;

/* prevent private mappings from being established */
- if ((vma->vm_flags & VM_MAYSHARE) != VM_MAYSHARE) {
+ if ((vm_flags & VM_MAYSHARE) != VM_MAYSHARE) {
dev_info_ratelimited(dev,
"%s: %s: fail, attempted private mapping\n",
current->comm, func);
@@ -31,15 +32,15 @@ static int check_vma(struct dev_dax *dev_dax, struct vm_area_struct *vma,
}

mask = dev_dax->align - 1;
- if (vma->vm_start & mask || vma->vm_end & mask) {
+ if (start & mask || end & mask) {
dev_info_ratelimited(dev,
"%s: %s: fail, unaligned vma (%#lx - %#lx, %#lx)\n",
- current->comm, func, vma->vm_start, vma->vm_end,
+ current->comm, func, start, end,
mask);
return -EINVAL;
}

- if (!vma_is_dax(vma)) {
+ if (!file_is_dax(file)) {
dev_info_ratelimited(dev,
"%s: %s: fail, vma is not DAX capable\n",
current->comm, func);
@@ -49,6 +50,13 @@ static int check_vma(struct dev_dax *dev_dax, struct vm_area_struct *vma,
return 0;
}

+static int check_vma(struct dev_dax *dev_dax, struct vm_area_struct *vma,
+ const char *func)
+{
+ return __check_vma(dev_dax, vma->vm_flags, vma->vm_start, vma->vm_end,
+ vma->vm_file, func);
+}
+
/* see "strong" declaration in tools/testing/nvdimm/dax-dev.c */
__weak phys_addr_t dax_pgoff_to_phys(struct dev_dax *dev_dax, pgoff_t pgoff,
unsigned long size)
@@ -285,8 +293,9 @@ static const struct vm_operations_struct dax_vm_ops = {
.pagesize = dev_dax_pagesize,
};

-static int dax_mmap(struct file *filp, struct vm_area_struct *vma)
+static int dax_mmap_prepare(struct vm_area_desc *desc)
{
+ struct file *filp = desc->file;
struct dev_dax *dev_dax = filp->private_data;
int rc, id;

@@ -297,13 +306,14 @@ static int dax_mmap(struct file *filp, struct vm_area_struct *vma)
* fault time.
*/
id = dax_read_lock();
- rc = check_vma(dev_dax, vma, __func__);
+ rc = __check_vma(dev_dax, desc->vm_flags, desc->start, desc->end, filp,
+ __func__);
dax_read_unlock(id);
if (rc)
return rc;

- vma->vm_ops = &dax_vm_ops;
- vm_flags_set(vma, VM_HUGEPAGE);
+ desc->vm_ops = &dax_vm_ops;
+ desc->vm_flags |= VM_HUGEPAGE;
return 0;
}

@@ -377,7 +387,7 @@ static const struct file_operations dax_fops = {
.open = dax_open,
.release = dax_release,
.get_unmapped_area = dax_get_unmapped_area,
- .mmap = dax_mmap,
+ .mmap_prepare = dax_mmap_prepare,
.fop_flags = FOP_MMAP_SYNC,
};

--
2.51.0