linux-kernel - [PATCH] mm, dax: use i_mmap_unlock_write() in do_cow

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Date:	Fri,  7 Aug 2015 14:54:42 +0300
From:	"Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
To:	Andrew Morton <akpm@...ux-foundation.org>,
	Matthew Wilcox <matthew.r.wilcox@...el.com>
Cc:	linux-mm@...ck.org, linux-fsdevel@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	"Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
Subject: [PATCH] mm, dax: use i_mmap_unlock_write() in do_cow_fault()

__dax_fault() takes i_mmap_lock for write. Let's pair it with write
unlock on do_cow_fault() side.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>
Acked-by: Matthew Wilcox <willy@...ux.intel.com>
---
 mm/memory.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/mm/memory.c b/mm/memory.c
index 670cdfa9f33e..7f6a9563d5a6 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -3013,9 +3013,9 @@ static int do_cow_fault(struct mm_struct *mm, struct vm_area_struct *vma,
 		} else {
 			/*
 			 * The fault handler has no page to lock, so it holds
-			 * i_mmap_lock for read to protect against truncate.
+			 * i_mmap_lock for write to protect against truncate.
 			 */
-			i_mmap_unlock_read(vma->vm_file->f_mapping);
+			i_mmap_unlock_write(vma->vm_file->f_mapping);
 		}
 		goto uncharge_out;
 	}
@@ -3029,9 +3029,9 @@ static int do_cow_fault(struct mm_struct *mm, struct vm_area_struct *vma,
 	} else {
 		/*
 		 * The fault handler has no page to lock, so it holds
-		 * i_mmap_lock for read to protect against truncate.
+		 * i_mmap_lock for write to protect against truncate.
 		 */
-		i_mmap_unlock_read(vma->vm_file->f_mapping);
+		i_mmap_unlock_write(vma->vm_file->f_mapping);
 	}
 	return ret;
 uncharge_out:
-- 
2.4.6

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