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Subject[PATCH 32/35] union-mount: Implement union-aware truncate()
Date
---
fs/open.c | 24 ++++++++++++++++++++----
1 files changed, 20 insertions(+), 4 deletions(-)
diff --git a/fs/open.c b/fs/open.c
index 325852d..dda1b6f 100644
--- a/fs/open.c
+++ b/fs/open.c
@@ -230,14 +230,17 @@ int do_truncate(struct dentry *dentry, loff_t length, unsigned int time_attrs,
static long do_sys_truncate(const char __user *pathname, loff_t length)
{
struct path path;
+ struct nameidata nd;
+ struct vfsmount *mnt;
struct inode *inode;
+ char *tmp;
int error;

error = -EINVAL;
if (length < 0) /* sorry, but loff_t says... */
goto out;

- error = user_path(pathname, &path);
+ error = user_path_nd(AT_FDCWD, pathname, 0, &nd, &path, &tmp);
if (error)
goto out;
inode = path.dentry->d_inode;
@@ -251,11 +254,16 @@ static long do_sys_truncate(const char __user *pathname, loff_t length)
if (!S_ISREG(inode->i_mode))
goto dput_and_out;

- error = mnt_want_write(path.mnt);
+ if (IS_UNIONED_DIR(&nd.path))
+ mnt = nd.path.mnt;
+ else
+ mnt = path.mnt;
+
+ error = mnt_want_write(mnt);
if (error)
goto dput_and_out;

- error = inode_permission(inode, MAY_WRITE);
+ error = path_permission(&path, &nd.path, MAY_WRITE);
if (error)
goto mnt_drop_write_and_out;

@@ -263,6 +271,12 @@ static long do_sys_truncate(const char __user *pathname, loff_t length)
if (IS_APPEND(inode))
goto mnt_drop_write_and_out;

+ error = union_copyup_len(&nd, &path, length);
+ if (error)
+ goto mnt_drop_write_and_out;
+
+ /* path may have changed after copyup */
+ inode = path.dentry->d_inode;
error = get_write_access(inode);
if (error)
goto mnt_drop_write_and_out;
@@ -284,9 +298,11 @@ static long do_sys_truncate(const char __user *pathname, loff_t length)
put_write_and_out:
put_write_access(inode);
mnt_drop_write_and_out:
- mnt_drop_write(path.mnt);
+ mnt_drop_write(mnt);
dput_and_out:
path_put(&path);
+ path_put(&nd.path);
+ putname(tmp);
out:
return error;
}
--
1.6.3.3


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