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

From: zhangaihua1
Date: Sun Jun 19 2016 - 22:47:26 EST


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