[PATCH 4.4-stable] tmpfs: don't undo fallocate past its last page

[PATCH 4.4-stable] tmpfs: don't undo fallocate past its last page

[Hugh Dickins]

This patch did not apply to the 4.4-stable tree, nor to the 3.14-stable
tree, because of 4.5's replacement of PAGE_CACHE_SHIFT by PAGE_SHIFT.
Please use the version below (diffed against 4.4.15) in any trees
from 3.5 through 4.5.

Thanks,
Hugh

>From b9b4bb26af017dbe930cd4df7f9b2fc3a0497bfe Mon Sep 17 00:00:00 2001
From: Anthony Romano <anthony.romano@coreos.com>
Date: Fri, 24 Jun 2016 14:48:43 -0700
Subject: tmpfs: don't undo fallocate past its last page

From: Anthony Romano <anthony.romano@coreos.com>

commit b9b4bb26af017dbe930cd4df7f9b2fc3a0497bfe upstream.

When fallocate is interrupted it will undo a range that extends one byte
past its range of allocated pages.  This can corrupt an in-use page by
zeroing out its first byte.  Instead, undo using the inclusive byte
range.

Fixes: 1635f6a74152f1d ("tmpfs: undo fallocation on failure")
Link: http://lkml.kernel.org/r/1462713387-16724-1-git-send-email-anthony.romano@coreos.com
Signed-off-by: Anthony Romano <anthony.romano@coreos.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Hugh Dickins <hughd@google.com>
Cc: Brandon Philips <brandon@ifup.co>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

---
 mm/shmem.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -2155,7 +2155,7 @@ static long shmem_fallocate(struct file
 			/* Remove the !PageUptodate pages we added */
 			shmem_undo_range(inode,
 				(loff_t)start << PAGE_CACHE_SHIFT,
-				(loff_t)index << PAGE_CACHE_SHIFT, true);
+				((loff_t)index << PAGE_CACHE_SHIFT) - 1, true);
 			goto undone;
 		}
 

Re: [PATCH 4.4-stable] tmpfs: don't undo fallocate past its last page

[Jiri Slaby]

On 07/25/2016, 04:37 PM, Hugh Dickins wrote:
> This patch did not apply to the 4.4-stable tree, nor to the 3.14-stable
> tree, because of 4.5's replacement of PAGE_CACHE_SHIFT by PAGE_SHIFT.
> Please use the version below (diffed against 4.4.15) in any trees
> from 3.5 through 4.5.

Applied both to 3.12. Thanks!

-- 
js
suse labs

Re: [PATCH 4.4-stable] tmpfs: don't undo fallocate past its last page

[Greg KH]

On Mon, Jul 25, 2016 at 07:37:21AM -0700, Hugh Dickins wrote:
> This patch did not apply to the 4.4-stable tree, nor to the 3.14-stable
> tree, because of 4.5's replacement of PAGE_CACHE_SHIFT by PAGE_SHIFT.
> Please use the version below (diffed against 4.4.15) in any trees
> from 3.5 through 4.5.

Thanks for these, now queued up.

greg k-h