[RFC][PATCH 06/13] chroot(2): import pathname only once

[Al Viro]

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 <v...@zeniv.linux.org.uk>
---
 fs/open.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/fs/open.c b/fs/open.c
index 8bc2f313f4a9..e67baae339fc 100644
--- a/fs/open.c
+++ b/fs/open.c
@@ -603,8 +603,9 @@ SYSCALL_DEFINE1(chroot, const char __user *, filename)
        struct path path;
        int error;
        unsigned int lookup_flags = LOOKUP_FOLLOW | LOOKUP_DIRECTORY;
+       struct filename *name = getname(filename);
 retry:
-       error = user_path_at(AT_FDCWD, filename, lookup_flags, &path);
+       error = filename_lookup(AT_FDCWD, name, lookup_flags, &path, NULL);
        if (error)
                goto out;
 
@@ -628,6 +629,7 @@ SYSCALL_DEFINE1(chroot, const char __user *, filename)
                goto retry;
        }
 out:
+       putname(name);
        return error;
 }
 
-- 
2.47.3