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From e3b50d463ce69af9fb5b2d4a54e6c37637c2ecef Mon Sep 17 00:00:00 2001
From: Bob Liu <lliubbo@gmail.com>
Date: Wed, 11 Jul 2012 14:02:35 -0700
Subject: [PATCH 042/109] fs: ramfs: file-nommu: add SetPageUptodate()
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: Ben Hutchings <ben@decadent.org.uk>
---
fs/ramfs/file-nommu.c | 1 +
1 files changed, 1 insertions(+), 0 deletions(-)
diff --git a/fs/ramfs/file-nommu.c b/fs/ramfs/file-nommu.c
index fbb0b47..d5378d0 100644
--- a/fs/ramfs/file-nommu.c
+++ b/fs/ramfs/file-nommu.c
@@ -110,6 +110,7 @@ int ramfs_nommu_expand_for_mapping(struct inode *inode, size_t newsize)
/* prevent the page from being discarded on memory pressure */
SetPageDirty(page);
+ SetPageUptodate(page);
unlock_page(page);
put_page(page);
--
1.7.7.6
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