linux-kernel - [PATCH 3.12 120/206] ext4: fix mmap data corruption when blocksize

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Date:	Tue, 18 Nov 2014 15:07:55 +0100
From:	Jiri Slaby <jslaby@...e.cz>
To:	stable@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org, Jan Kara <jack@...e.cz>,
	Theodore Ts'o <tytso@....edu>, Jiri Slaby <jslaby@...e.cz>
Subject: [PATCH 3.12 120/206] ext4: fix mmap data corruption when blocksize < pagesize

From: Jan Kara <jack@...e.cz>

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

===============

commit d6320cbfc92910a3e5f10c42d98c231c98db4f60 upstream.

Use truncate_isize_extended() when hole is being created in a file so that
->page_mkwrite() will get called for the partial tail page if it is
mmaped (see the first patch in the series for details).

Signed-off-by: Jan Kara <jack@...e.cz>
Signed-off-by: Theodore Ts'o <tytso@....edu>
Signed-off-by: Jiri Slaby <jslaby@...e.cz>
---
 fs/ext4/inode.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index d65a6260ad61..474b9eafee43 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -4655,8 +4655,12 @@ int ext4_setattr(struct dentry *dentry, struct iattr *attr)
 				ext4_orphan_del(NULL, inode);
 				goto err_out;
 			}
-		} else
+		} else {
+			loff_t oldsize = inode->i_size;
+
 			i_size_write(inode, attr->ia_size);
+			pagecache_isize_extended(inode, oldsize, inode->i_size);
+		}
 
 		/*
 		 * Blocks are going to be removed from the inode. Wait
-- 
2.1.3

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