path_openat(): take O_PATH handling out of do_last()

do_last() and lookup_open() simpler that way and so does O_PATH
itself.  As it bloody well should: we find what the pathname
resolves to, same way as in stat() et.al. and associate it with
FMODE_PATH struct file.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

diff --git a/fs/namei.c b/fs/namei.c
index 8249852..8145b41 100644 (file)
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -3019,7 +3019,7 @@ static int lookup_open(struct nameidata *nd, struct path *path,
                goto out_no_open;
        }
 
-       if ((nd->flags & LOOKUP_OPEN) && dir_inode->i_op->atomic_open) {
+       if (dir_inode->i_op->atomic_open) {
                return atomic_open(nd, dentry, path, file, op, got_write,
                                   need_lookup, opened);
        }
@@ -3219,7 +3219,7 @@ finish_open:
                return error;
        }
        audit_inode(nd->name, nd->path.dentry, 0);
-       if (unlikely(d_is_symlink(nd->path.dentry)) && !(open_flag & O_PATH)) {
+       if (unlikely(d_is_symlink(nd->path.dentry))) {
                error = -ELOOP;
                goto out;
        }
@@ -3239,11 +3239,9 @@ finish_open:
                got_write = true;
        }
 finish_open_created:
-       if (likely(!(open_flag & O_PATH))) {
-               error = may_open(&nd->path, acc_mode, open_flag);
-               if (error)
-                       goto out;
-       }
+       error = may_open(&nd->path, acc_mode, open_flag);
+       if (error)
+               goto out;
        BUG_ON(*opened & FILE_OPENED); /* once it's opened, it's opened */
        error = vfs_open(&nd->path, file, current_cred());
        if (!error) {
@@ -3357,6 +3355,18 @@ out:
        return error;
 }
 
+static int do_o_path(struct nameidata *nd, unsigned flags, struct file *file)
+{
+       struct path path;
+       int error = path_lookupat(nd, flags, &path);
+       if (!error) {
+               audit_inode(nd->name, path.dentry, 0);
+               error = vfs_open(&path, file, current_cred());
+               path_put(&path);
+       }
+       return error;
+}
+
 static struct file *path_openat(struct nameidata *nd,
                        const struct open_flags *op, unsigned flags)
 {
@@ -3376,6 +3386,13 @@ static struct file *path_openat(struct nameidata *nd,
                goto out2;
        }
 
+       if (unlikely(file->f_flags & O_PATH)) {
+               error = do_o_path(nd, flags, file);
+               if (!error)
+                       opened |= FILE_OPENED;
+               goto out2;
+       }
+
        s = path_init(nd, flags);
        if (IS_ERR(s)) {
                put_filp(file);