linux-kernel - [PATCH v2 0/2] open: make RESOLVE_CACHED correctly test for O

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Message-Id: <20230806-resolve_cached-o_tmpfile-v2-0-058bff24fb16@cyphar.com>
Date:   Sun, 06 Aug 2023 08:48:07 +1000
From:   Aleksa Sarai <cyphar@...har.com>
To:     Alexander Viro <viro@...iv.linux.org.uk>,
        Christian Brauner <brauner@...nel.org>,
        Jens Axboe <axboe@...nel.dk>,
        Pavel Begunkov <asml.silence@...il.com>
Cc:     linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
        io-uring@...r.kernel.org, Aleksa Sarai <cyphar@...har.com>,
        stable@...r.kernel.org
Subject: [PATCH v2 0/2] open: make RESOLVE_CACHED correctly test for
 O_TMPFILE

There were a few places that were incorrectly testing for whether an
open(2) operation was O_TMPFILE by doing (flags & O_TMPFILE). As
O_TMPFILE is defined as __O_TMPFILE|O_DIRECTORY, this would cause the
code to assume that O_DIRECTORY is equivalent to O_TMPFILE.

The only places where this happened were in RESOLVE_CACHED and
io_uring's checking related to RESOLVE_CACHED, so the only bug this
really fixes is that now O_DIRECTORY will no longer cause RESOLVE_CACHED
to always fail with -EAGAIN (and io_uring will thus be faster when doing
O_DIRECTORY opens).

Signed-off-by: Aleksa Sarai <cyphar@...har.com>
---
Changes in v2:
- fix io_uring's io_openat_force_async as well.
- v1: <https://lore.kernel.org/r/20230806-resolve_cached-o_tmpfile-v1-1-7ba16308465e@cyphar.com>

---
Aleksa Sarai (2):
      open: make RESOLVE_CACHED correctly test for O_TMPFILE
      io_uring: correct check for O_TMPFILE

 fs/open.c            | 2 +-
 io_uring/openclose.c | 4 ++--
 2 files changed, 3 insertions(+), 3 deletions(-)
---
base-commit: bf5ad7af0516cb47121dae1b1c160e4385615274
change-id: 20230806-resolve_cached-o_tmpfile-978cb238bd68

Best regards,
-- 
Aleksa Sarai <cyphar@...har.com>