lkml.org 
[lkml]   [2012]   [Jul]   [12]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[ 185/187] fs: ramfs: file-nommu: add SetPageUptodate()
Date
From: Greg KH <gregkh@linuxfoundation.org>

3.4-stable review patch. If anyone has any objections, please let me know.

------------------

From: Bob Liu <lliubbo@gmail.com>

commit fea9f718b3d68147f162ed2d870183ce5e0ad8d8 upstream.

There is a bug in the below scenario for !CONFIG_MMU:

1. create a new file
2. mmap the file and write to it
3. read the file can't get the correct value

Because

sys_read() -> generic_file_aio_read() -> simple_readpage() -> clear_page()

which causes the page to be zeroed.

Add SetPageUptodate() to ramfs_nommu_expand_for_mapping() so that
generic_file_aio_read() do not call simple_readpage().

Signed-off-by: Bob Liu <lliubbo@gmail.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Greg Ungerer <gerg@uclinux.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
fs/ramfs/file-nommu.c | 1 +
1 file changed, 1 insertion(+)

--- a/fs/ramfs/file-nommu.c
+++ b/fs/ramfs/file-nommu.c
@@ -110,6 +110,7 @@ int ramfs_nommu_expand_for_mapping(struc

/* prevent the page from being discarded on memory pressure */
SetPageDirty(page);
+ SetPageUptodate(page);

unlock_page(page);
put_page(page);



\
 
 \ /
  Last update: 2012-07-13 05:01    [W:0.390 / U:1.268 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site