[PATCH v2 1/5] dax: fix vma_is_fsdax() helper

[Dan Williams]

Gerd reports that ->i_mode may contain other bits besides S_IFCHR. Use
S_ISCHR() instead. Otherwise, get_user_pages_longterm() may fail on
device-dax instances when those are meant to be explicitly allowed.

Fixes: 2bb6d2837083 ("mm: introduce get_user_pages_longterm")
Cc: 
Reported-by: Gerd Rausch 
Reported-by: Haozhong Zhang 
Signed-off-by: Dan Williams 
---
 include/linux/fs.h |2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/linux/fs.h b/include/linux/fs.h
index 2a815560fda0..79c413985305 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -3198,7 +3198,7 @@ static inline bool vma_is_fsdax(struct vm_area_struct 
*vma)
if (!vma_is_dax(vma))
return false;
inode = file_inode(vma->vm_file);
-   if (inode->i_mode == S_IFCHR)
+   if (S_ISCHR(inode->i_mode))
return false; /* device-dax */
return true;
 }

[PATCH v2 1/5] dax: fix vma_is_fsdax() helper

[Dan Williams]

Gerd reports that ->i_mode may contain other bits besides S_IFCHR. Use
S_ISCHR() instead. Otherwise, get_user_pages_longterm() may fail on
device-dax instances when those are meant to be explicitly allowed.

Fixes: 2bb6d2837083 ("mm: introduce get_user_pages_longterm")
Cc: 
Reported-by: Gerd Rausch 
Reported-by: Haozhong Zhang 
Signed-off-by: Dan Williams 
---
 include/linux/fs.h |2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/linux/fs.h b/include/linux/fs.h
index 2a815560fda0..79c413985305 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -3198,7 +3198,7 @@ static inline bool vma_is_fsdax(struct vm_area_struct 
*vma)
if (!vma_is_dax(vma))
return false;
inode = file_inode(vma->vm_file);
-   if (inode->i_mode == S_IFCHR)
+   if (S_ISCHR(inode->i_mode))
return false; /* device-dax */
return true;
 }