From: Dan Williams <dan.j.williams@intel.com>
Date: Wed, 24 Feb 2016 22:02:06 +0000 (-0800)
Subject: dax: fallback from pmd to pte on error
X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=8b3db9798c689ba2dc509f6ca1a8c7e1c1a3e62a;p=GitHub%2Fmoto-9609%2Fandroid_kernel_motorola_exynos9610.git

dax: fallback from pmd to pte on error

In preparation for consulting a badblocks list in pmem_direct_access(),
teach dax_pmd_fault() to fallback rather than fail immediately upon
encountering an error.  The thought being that reducing the span of the
dax request may avoid the error region.

Reviewed-by: Jeff Moyer <jmoyer@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Vishal Verma <vishal.l.verma@intel.com>
---

diff --git a/fs/dax.c b/fs/dax.c
index 9bc6624251b4..d602410d8e52 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -855,8 +855,8 @@ int __dax_pmd_fault(struct vm_area_struct *vma, unsigned long address,
 		long length = dax_map_atomic(bdev, &dax);
 
 		if (length < 0) {
-			result = VM_FAULT_SIGBUS;
-			goto out;
+			dax_pmd_dbg(&bh, address, "dax-error fallback");
+			goto fallback;
 		}
 		if (length < PMD_SIZE) {
 			dax_pmd_dbg(&bh, address, "dax-length too small");