From: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Date: Mon, 16 Jun 2025 19:33:23 +0000 (+0100)
Subject: fs/dax: make it possible to check dev dax support without a VMA
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=0335f6afd3488d1101f3b15014095fa51b978253;p=thirdparty%2Fkernel%2Fstable.git

fs/dax: make it possible to check dev dax support without a VMA

This is a prerequisite for adapting those filesystems to use the
.mmap_prepare() hook for mmap()'ing which invoke this check as this hook
does not have access to a VMA pointer.

To effect this, change the signature of daxdev_mapping_supported() and
update its callers (ext4 and xfs mmap()'ing hook code).

Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Link: https://lore.kernel.org/b09de1e8544384074165d92d048e80058d971286.1750099179.git.lorenzo.stoakes@oracle.com
Signed-off-by: Christian Brauner <brauner@kernel.org>
---

diff --git a/fs/ext4/file.c b/fs/ext4/file.c
index 21df81347147c..5b8b95936a4cf 100644
--- a/fs/ext4/file.c
+++ b/fs/ext4/file.c
@@ -821,7 +821,7 @@ static int ext4_file_mmap(struct file *file, struct vm_area_struct *vma)
 	 * We don't support synchronous mappings for non-DAX files and
 	 * for DAX files if underneath dax_device is not synchronous.
 	 */
-	if (!daxdev_mapping_supported(vma, dax_dev))
+	if (!daxdev_mapping_supported(vma->vm_flags, file_inode(vma->vm_file), dax_dev))
 		return -EOPNOTSUPP;
 
 	file_accessed(file);
diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
index 48254a72071bc..1160eba8727f5 100644
--- a/fs/xfs/xfs_file.c
+++ b/fs/xfs/xfs_file.c
@@ -1924,7 +1924,8 @@ xfs_file_mmap(
 	 * We don't support synchronous mappings for non-DAX files and
 	 * for DAX files if underneath dax_device is not synchronous.
 	 */
-	if (!daxdev_mapping_supported(vma, target->bt_daxdev))
+	if (!daxdev_mapping_supported(vma->vm_flags, file_inode(vma->vm_file),
+				      target->bt_daxdev))
 		return -EOPNOTSUPP;
 
 	file_accessed(file);
diff --git a/include/linux/dax.h b/include/linux/dax.h
index dcc9fcdf14e43..78891518291d8 100644
--- a/include/linux/dax.h
+++ b/include/linux/dax.h
@@ -65,12 +65,13 @@ size_t dax_recovery_write(struct dax_device *dax_dev, pgoff_t pgoff,
 /*
  * 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)
+static inline bool daxdev_mapping_supported(vm_flags_t vm_flags,
+					    const struct inode *inode,
+					    struct dax_device *dax_dev)
 {
-	if (!(vma->vm_flags & VM_SYNC))
+	if (!(vm_flags & VM_SYNC))
 		return true;
-	if (!IS_DAX(file_inode(vma->vm_file)))
+	if (!IS_DAX(inode))
 		return false;
 	return dax_synchronous(dax_dev);
 }
@@ -110,10 +111,11 @@ static inline void set_dax_nomc(struct dax_device *dax_dev)
 static inline void set_dax_synchronous(struct dax_device *dax_dev)
 {
 }
-static inline bool daxdev_mapping_supported(struct vm_area_struct *vma,
-				struct dax_device *dax_dev)
+static inline bool daxdev_mapping_supported(vm_flags_t vm_flags,
+					    const struct inode *inode,
+					    struct dax_device *dax_dev)
 {
-	return !(vma->vm_flags & VM_SYNC);
+	return !(vm_flags & VM_SYNC);
 }
 static inline size_t dax_recovery_write(struct dax_device *dax_dev,
 		pgoff_t pgoff, void *addr, size_t bytes, struct iov_iter *i)