[RFC][PATCH 08/13] do_sys_truncate(): import pathname only once

Al Viro
2025-11-09T06:37:47Z

Convert the user_path_at() call inside a retry loop into getname_flags() +
filename_lookup() + putname() and leave only filename_lookup() inside
the loop.

In this case we never pass LOOKUP_EMPTY, so getname_flags() is equivalent
to plain getname().

The things could be further simplified by use of cleanup.h stuff, but
let's not clutter the patch with that.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
fs/open.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/fs/open.c b/fs/open.c
index e67baae339fc..eb2ff940393d 100644
--- a/fs/open.c
+++ b/fs/open.c
@@ -129,14 +129,16 @@ EXPORT_SYMBOL_GPL(vfs_truncate);
int do_sys_truncate(const char __user *pathname, loff_t length)
{
unsigned int lookup_flags = LOOKUP_FOLLOW;
+ struct filename *name;
struct path path;
int error;

if (length < 0) /* sorry, but loff_t says... */
return -EINVAL;

+ name = getname(pathname);
retry:
- error = user_path_at(AT_FDCWD, pathname, lookup_flags, &path);
+ error = filename_lookup(AT_FDCWD, name, lookup_flags, &path, NULL);
if (!error) {
error = vfs_truncate(&path, length);
path_put(&path);
@@ -145,6 +147,7 @@ int do_sys_truncate(const char __user *pathname, loff_t length)
lookup_flags |= LOOKUP_REVAL;
goto retry;
}
+ putname(name);
return error;
}

--
2.47.3