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[46.135.69.142]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-acb3d128c9esm194762866b.108.2025.04.16.15.16.30 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 16 Apr 2025 15:16:33 -0700 (PDT) From: Mateusz Guzik To: brauner@kernel.org Cc: torvalds@linux-foundation.org, viro@zeniv.linux.org.uk, jack@suse.cz, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, Mateusz Guzik Subject: [PATCH 0/2] two nits for path lookup Date: Thu, 17 Apr 2025 00:16:24 +0200 Message-ID: <20250416221626.2710239-1-mjguzik@gmail.com> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 since path looku is being looked at, two extra nits from me: 1. some trivial jump avoidance in inode_permission() 2. but more importantly avoiding a memory access which is most likely a cache miss when descending into devcgroup_inode_permission() the file seems to have no maintainer fwiw anyhow I'm confident the way forward is to add IOP_FAST_MAY_EXEC (or similar) to elide inode_permission() in the common case to begin with. There are quite a few branches which straight up don't need execute. On top of that btrfs has a permission hook only to check for MAY_WRITE, which in case of path lookup is not set. With the above flag the call will be avoided. Mateusz Guzik (2): fs: touch up predicts in inode_permission() device_cgroup: avoid access to ->i_rdev in the common case in devcgroup_inode_permission() fs/namei.c | 10 +++++----- include/linux/device_cgroup.h | 7 ++++--- 2 files changed, 9 insertions(+), 8 deletions(-)