linux-kernel - [PATCH 08/16] mm/nommu: switch do_mmap_private to kernel

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Message-Id: <20170830150007.3953-9-hch@lst.de>
Date:   Wed, 30 Aug 2017 16:59:59 +0200
From:   Christoph Hellwig <hch@....de>
To:     viro@...iv.linux.org.uk
Cc:     arve@...roid.com, riandrews@...roid.com,
        linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH 08/16] mm/nommu: switch do_mmap_private to kernel_read

Instead of playing with the address limit.  This also gains us
validation of the kvec and proper atime updates.

Signed-off-by: Christoph Hellwig <hch@....de>
---
 mm/nommu.c | 13 ++-----------
 1 file changed, 2 insertions(+), 11 deletions(-)

diff --git a/mm/nommu.c b/mm/nommu.c
index fc184f597d59..379f1022bdea 100644
--- a/mm/nommu.c
+++ b/mm/nommu.c
@@ -1164,17 +1164,8 @@ static int do_mmap_private(struct vm_area_struct *vma,
 
 	if (vma->vm_file) {
 		/* read the contents of a file into the copy */
-		mm_segment_t old_fs;
-		loff_t fpos;
-
-		fpos = vma->vm_pgoff;
-		fpos <<= PAGE_SHIFT;
-
-		old_fs = get_fs();
-		set_fs(KERNEL_DS);
-		ret = __vfs_read(vma->vm_file, base, len, &fpos);
-		set_fs(old_fs);
-
+		loff_t fpos = vma->vm_pgoff << PAGE_SHIFT;
+		ret = kernel_read(vma->vm_file, base, len, &fpos);
 		if (ret < 0)
 			goto error_free;
 
-- 
2.11.0