namei: ignore ERR/NULL names in putname()

Supporting ERR/NULL names in putname() makes callers code cleaner, and
is what some other path walking functions already support for the same
reason.

This also removes a few existing IS_ERR checks before putname().

Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/io-uring/CAHk-=wgCac9hBsYzKMpHk0EbLgQaXR=OUAjHaBtaY+G8A9KhFg@mail.gmail.com/
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Christian Brauner <christian.brauner@ubuntu.com>
Signed-off-by: Dmitry Kadashev <dkadashev@gmail.com>
Link: https://lore.kernel.org/r/20210708063447.3556403-2-dkadashev@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/fs/namei.c b/fs/namei.c
index bf6d8a738c599e62bf6de18b59c27cf2bd19725f..dc36bda5c2e72d92ebb596e08ec7ffaaa1e709d1 100644 (file)
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -247,6 +247,9 @@ getname_kernel(const char * filename)
 
 void putname(struct filename *name)
 {
+       if (IS_ERR_OR_NULL(name))
+               return;
+
        BUG_ON(name->refcnt <= 0);
 
        if (--name->refcnt > 0)
@@ -4728,11 +4731,9 @@ exit1:
                goto retry;
        }
 put_both:
-       if (!IS_ERR(from))
-               putname(from);
+       putname(from);
 put_new:
-       if (!IS_ERR(to))
-               putname(to);
+       putname(to);
        return error;
 }