vfs: Fix O_NOFOLLOW behavior for paths with trailing slashes

According to specification

	mkdir d; ln -s d a; open("a/", O_NOFOLLOW | O_RDONLY)

should return success but currently it returns ELOOP.  This is a
regression caused by path lookup cleanup patch series.

Fix the code to ignore O_NOFOLLOW in case the provided path has trailing
slashes.

Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Reported-by: Marius Tolzmann <tolzmann@molgen.mpg.de>
Acked-by: Miklos Szeredi <mszeredi@suse.cz>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/fs/namei.c b/fs/namei.c
index a7dce91..16df727 100644 (file)
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -1641,7 +1641,7 @@ static struct file *do_last(struct nameidata *nd, struct path *path,
        if (nd->last.name[nd->last.len]) {
                if (open_flag & O_CREAT)
                        goto exit;
-               nd->flags |= LOOKUP_DIRECTORY;
+               nd->flags |= LOOKUP_DIRECTORY | LOOKUP_FOLLOW;
        }
 
        /* just plain open? */
@@ -1830,6 +1830,8 @@ reval:
        }
        if (open_flag & O_DIRECTORY)
                nd.flags |= LOOKUP_DIRECTORY;
+       if (!(open_flag & O_NOFOLLOW))
+               nd.flags |= LOOKUP_FOLLOW;
        filp = do_last(&nd, &path, open_flag, acc_mode, mode, pathname);
        while (unlikely(!filp)) { /* trailing symlink */
                struct path holder;
@@ -1837,7 +1839,7 @@ reval:
                void *cookie;
                error = -ELOOP;
                /* S_ISDIR part is a temporary automount kludge */
-               if ((open_flag & O_NOFOLLOW) && !S_ISDIR(inode->i_mode))
+               if (!(nd.flags & LOOKUP_FOLLOW) && !S_ISDIR(inode->i_mode))
                        goto exit_dput;
                if (count++ == 32)
                        goto exit_dput;