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[46.135.88.146]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-3ee073f53c4sm8446746f8f.3.2025.09.19.08.49.22 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 19 Sep 2025 08:49:23 -0700 (PDT) From: Mateusz Guzik To: brauner@kernel.org Cc: viro@zeniv.linux.org.uk, jack@suse.cz, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, josef@toxicpanda.com, kernel-team@fb.com, amir73il@gmail.com, linux-btrfs@vger.kernel.org, linux-ext4@vger.kernel.org, linux-xfs@vger.kernel.org, ceph-devel@vger.kernel.org, linux-unionfs@vger.kernel.org, Mateusz Guzik Subject: [PATCH v5 4/4] fs: make plain ->i_state access fail to compile Date: Fri, 19 Sep 2025 17:49:04 +0200 Message-ID: <20250919154905.2592318-5-mjguzik@gmail.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20250919154905.2592318-1-mjguzik@gmail.com> References: <20250919154905.2592318-1-mjguzik@gmail.com> Precedence: bulk X-Mailing-List: linux-unionfs@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit ... to make sure all accesses are properly validated. Merely renaming the var to __i_state still lets the compiler make the following suggestion: error: 'struct inode' has no member named 'i_state'; did you mean '__i_state'? Unfortunately some people will add the __'s and call it a day. In order to make it harder to mess up in this way, hide it behind a struct. The resulting error message should be convincing in terms of checking what to do: error: invalid operands to binary & (have 'struct inode_state_flags' and 'int') Of course people determined to do a plain access can still do it, but nothing can be done for that case. Signed-off-by: Mateusz Guzik --- include/linux/fs.h | 17 ++++++++++++----- 1 file changed, 12 insertions(+), 5 deletions(-) diff --git a/include/linux/fs.h b/include/linux/fs.h index 4ba2b274588a..3d678cd02fea 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -782,6 +782,13 @@ enum inode_state_flags_enum { #define I_DIRTY (I_DIRTY_INODE | I_DIRTY_PAGES) #define I_DIRTY_ALL (I_DIRTY | I_DIRTY_TIME) +/* + * Use inode_state_read() & friends to access. + */ +struct inode_state_flags { + enum inode_state_flags_enum __state; +}; + /* * Keep mostly read-only and often accessed (especially for * the RCU path lookup and 'stat' data) fields at the beginning @@ -840,7 +847,7 @@ struct inode { #endif /* Misc */ - enum inode_state_flags_enum i_state; + struct inode_state_flags i_state; /* 32-bit hole */ struct rw_semaphore i_rwsem; @@ -906,26 +913,26 @@ struct inode { */ static inline enum inode_state_flags_enum inode_state_read(struct inode *inode) { - return READ_ONCE(inode->i_state); + return READ_ONCE(inode->i_state.__state); } static inline void inode_state_add(struct inode *inode, enum inode_state_flags_enum addflags) { - WRITE_ONCE(inode->i_state, inode->i_state | addflags); + WRITE_ONCE(inode->i_state.__state, inode->i_state.__state | addflags); } static inline void inode_state_del(struct inode *inode, enum inode_state_flags_enum delflags) { - WRITE_ONCE(inode->i_state, inode->i_state & ~delflags); + WRITE_ONCE(inode->i_state.__state, inode->i_state.__state & ~delflags); } static inline void inode_state_set(struct inode *inode, enum inode_state_flags_enum setflags) { - WRITE_ONCE(inode->i_state, setflags); + WRITE_ONCE(inode->i_state.__state, setflags); } static inline void inode_set_cached_link(struct inode *inode, char *link, int linklen) -- 2.43.0