[PATCH 3.14 100/203] ext4: fix mmap data corruption when blocksize < pagesize

From: Greg Kroah-Hartman
Date: Tue Nov 11 2014 - 21:54:24 EST


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

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

From: Jan Kara <jack@xxxxxxx>

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@xxxxxxx>
Signed-off-by: Theodore Ts'o <tytso@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
fs/ext4/inode.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)

--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -4645,8 +4645,12 @@ int ext4_setattr(struct dentry *dentry,
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


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