[PATCH v2] dax: check return value of dax_radix_entry()

[PATCH v2] dax: check return value of dax_radix_entry()

[Ross Zwisler]

dax_pfn_mkwrite() previously wasn't checking the return value of the call
to dax_radix_entry(), which was a mistake.

Instead, capture this return value and return the appropriate VM_FAULT_
value.

Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com>
---
 fs/dax.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/fs/dax.c b/fs/dax.c
index 7111724..bbb2ad7 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -1056,6 +1056,7 @@ EXPORT_SYMBOL_GPL(dax_pmd_fault);
 int dax_pfn_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
 {
 	struct file *file = vma->vm_file;
+	int error;
 
 	/*
 	 * We pass NO_SECTOR to dax_radix_entry() because we expect that a
@@ -1065,7 +1066,13 @@ int dax_pfn_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
 	 * saves us from having to make a call to get_block() here to look
 	 * up the sector.
 	 */
-	dax_radix_entry(file->f_mapping, vmf->pgoff, NO_SECTOR, false, true);
+	error = dax_radix_entry(file->f_mapping, vmf->pgoff, NO_SECTOR, false,
+			true);
+
+	if (error == -ENOMEM)
+		return VM_FAULT_OOM;
+	if (error)
+		return VM_FAULT_SIGBUS;
 	return VM_FAULT_NOPAGE;
 }
 EXPORT_SYMBOL_GPL(dax_pfn_mkwrite);
-- 
2.5.0

Re: [PATCH v2] dax: check return value of dax_radix_entry()

[Dave Chinner]

On Wed, Mar 02, 2016 at 10:00:51AM -0700, Ross Zwisler wrote:
> dax_pfn_mkwrite() previously wasn't checking the return value of the call
> to dax_radix_entry(), which was a mistake.
> 
> Instead, capture this return value and return the appropriate VM_FAULT_
> value.
> 
> Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com>

Hi Ross,

Can you please cc dax stuff to linux-fsdevel? it is way too easy to
miss stuff like this when lkml is the only list it's sent to?

That said, the change looks good.

Cheers,

Dave.
-- 
Dave Chinner
david@fromorbit.com

Re: [PATCH v2] dax: check return value of dax_radix_entry()

[Ross Zwisler]

On Thu, Mar 03, 2016 at 02:49:11PM +1100, Dave Chinner wrote:
> On Wed, Mar 02, 2016 at 10:00:51AM -0700, Ross Zwisler wrote:
> > dax_pfn_mkwrite() previously wasn't checking the return value of the call
> > to dax_radix_entry(), which was a mistake.
> > 
> > Instead, capture this return value and return the appropriate VM_FAULT_
> > value.
> > 
> > Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com>
> 
> Hi Ross,
> 
> Can you please cc dax stuff to linux-fsdevel? it is way too easy to
> miss stuff like this when lkml is the only list it's sent to?

Sure, will do.