do_faccessat(): import pathname only once

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

Since we have the default logics for use of LOOKUP_EMPTY (passed iff
AT_EMPTY_PATH is present in flags), just use getname_uflags() and
don't bother with setting LOOKUP_EMPTY in lookup_flags - getname_uflags()
will pass the right thing to getname_flags() and filename_lookup()
doesn't care about LOOKUP_EMPTY at all.

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>

diff --git a/fs/open.c b/fs/open.c
index f328622061c56cffb5f7355340725f261e9ab42a..f3bacc583ef0137d84dd6844a853ae075091d6d8 100644 (file)
--- a/fs/open.c
+++ b/fs/open.c
@@ -468,6 +468,7 @@ static int do_faccessat(int dfd, const char __user *filename, int mode, int flag
        int res;
        unsigned int lookup_flags = LOOKUP_FOLLOW;
        const struct cred *old_cred = NULL;
+       struct filename *name;
 
        if (mode & ~S_IRWXO)    /* where's F_OK, X_OK, W_OK, R_OK? */
                return -EINVAL;
@@ -477,8 +478,6 @@ static int do_faccessat(int dfd, const char __user *filename, int mode, int flag
 
        if (flags & AT_SYMLINK_NOFOLLOW)
                lookup_flags &= ~LOOKUP_FOLLOW;
-       if (flags & AT_EMPTY_PATH)
-               lookup_flags |= LOOKUP_EMPTY;
 
        if (access_need_override_creds(flags)) {
                old_cred = access_override_creds();
@@ -486,8 +485,9 @@ static int do_faccessat(int dfd, const char __user *filename, int mode, int flag
                        return -ENOMEM;
        }
 
+       name = getname_uflags(filename, flags);
 retry:
-       res = user_path_at(dfd, filename, lookup_flags, &path);
+       res = filename_lookup(dfd, name, lookup_flags, &path, NULL);
        if (res)
                goto out;
 
@@ -527,6 +527,7 @@ out_path_release:
                goto retry;
        }
 out:
+       putname(name);
        if (old_cred)
                put_cred(revert_creds(old_cred));