[PATCH] fix error: a bin file can truncate itself while running at overlayfs.

[zhangaihua1]

From: Aihua Zhang <zhangaihua1@xxxxxxxxxx>

I wrote a testcase to truncate a bin file while it is running at overlayfs.
the result as below:

Bus error (core dumped)

I think it's not appropriate for filesystem, and fixed it by this patch.
after the patch, result as below:

status:-1
errno:26
ETXTBSY:26
PASS

This is because the inode is not correct ,it should point to overlayfs rather
than the upper filesystem.

Signed-off-by: Aihua Zhang <zhangaihua1@xxxxxxxxxx>
---
 include/linux/fs.h |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/include/linux/fs.h b/include/linux/fs.h
index dd28814..54fdbf9 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -2589,7 +2589,7 @@ static inline int get_write_access(struct inode *inode)
 }
 static inline int deny_write_access(struct file *file)
 {
-	struct inode *inode = file_inode(file);
+	struct inode *inode = d_inode(file->f_path.dentry);
 	return atomic_dec_unless_positive(&inode->i_writecount) ? 0 : -ETXTBSY;
 }
 static inline void put_write_access(struct inode * inode)
-- 
1.7.1