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Message-ID: <20250919154905.2592318-1-mjguzik@gmail.com>
Date: Fri, 19 Sep 2025 17:49:00 +0200
From: Mateusz Guzik <mjguzik@...il.com>
To: brauner@...nel.org
Cc: viro@...iv.linux.org.uk,
	jack@...e.cz,
	linux-kernel@...r.kernel.org,
	linux-fsdevel@...r.kernel.org,
	josef@...icpanda.com,
	kernel-team@...com,
	amir73il@...il.com,
	linux-btrfs@...r.kernel.org,
	linux-ext4@...r.kernel.org,
	linux-xfs@...r.kernel.org,
	ceph-devel@...r.kernel.org,
	linux-unionfs@...r.kernel.org,
	Mateusz Guzik <mjguzik@...il.com>
Subject: [PATCH v5 0/4] hide ->i_state behind accessors

This is generated against:
https://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs.git/commit/?h=vfs-6.18.inode.refcount.preliminaries

First commit message quoted verbatim with rationable + API:

[quote]
Open-coded accesses prevent asserting they are done correctly. One
obvious aspect is locking, but significantly more can checked. For
example it can be detected when the code is clearing flags which are
already missing, or is setting flags when it is illegal (e.g., I_FREEING
when ->i_count > 0).

Given the late stage of the release cycle this patchset only aims to
hide access, it does not provide any of the checks.

Consumers can be trivially converted. Suppose flags I_A and I_B are to
be handled, then:

state = inode->i_state  	=> state = inode_state_read(inode)
inode->i_state |= (I_A | I_B) 	=> inode_state_add(inode, I_A | I_B)
inode->i_state &= ~(I_A | I_B) 	=> inode_state_del(inode, I_A | I_B)
inode->i_state = I_A | I_B	=> inode_state_set(inode, I_A | I_B)
[/quote]

Right now this is one big NOP, except for READ_ONCE/WRITE_ONCE for every access.

Given this, I decided to not submit any per-fs patches. Instead, the
conversion is done in 2 parts: coccinelle and whatever which was missed.

v5:
- drop lockdep for the time being

v4:
https://lore.kernel.org/linux-fsdevel/CAGudoHFViBUZ4TPNuLWC7qyK0v8LRwxbpZd9Mx3rHdh5GW9CrQ@mail.gmail.com/T/#m866b3b5740691de9b4008184a9a3f922dfa8e439

Mateusz Guzik (4):
  fs: provide accessors for ->i_state
  Convert the kernel to use ->i_state accessors
  Manual conversion of ->i_state uses
  fs: make plain ->i_state access fail to compile

 Documentation/filesystems/porting.rst |   2 +-
 block/bdev.c                          |   4 +-
 drivers/dax/super.c                   |   2 +-
 fs/9p/vfs_inode.c                     |   2 +-
 fs/9p/vfs_inode_dotl.c                |   2 +-
 fs/affs/inode.c                       |   2 +-
 fs/afs/dynroot.c                      |   6 +-
 fs/afs/inode.c                        |   6 +-
 fs/bcachefs/fs.c                      |   8 +-
 fs/befs/linuxvfs.c                    |   2 +-
 fs/bfs/inode.c                        |   2 +-
 fs/btrfs/inode.c                      |  10 +--
 fs/buffer.c                           |   4 +-
 fs/ceph/cache.c                       |   2 +-
 fs/ceph/crypto.c                      |   4 +-
 fs/ceph/file.c                        |   4 +-
 fs/ceph/inode.c                       |  28 +++---
 fs/coda/cnode.c                       |   4 +-
 fs/cramfs/inode.c                     |   2 +-
 fs/crypto/keyring.c                   |   2 +-
 fs/crypto/keysetup.c                  |   2 +-
 fs/dcache.c                           |   8 +-
 fs/drop_caches.c                      |   2 +-
 fs/ecryptfs/inode.c                   |   6 +-
 fs/efs/inode.c                        |   2 +-
 fs/erofs/inode.c                      |   2 +-
 fs/ext2/inode.c                       |   2 +-
 fs/ext4/inode.c                       |  10 +--
 fs/ext4/orphan.c                      |   4 +-
 fs/f2fs/data.c                        |   2 +-
 fs/f2fs/inode.c                       |   2 +-
 fs/f2fs/namei.c                       |   4 +-
 fs/f2fs/super.c                       |   2 +-
 fs/freevxfs/vxfs_inode.c              |   2 +-
 fs/fs-writeback.c                     | 121 +++++++++++++-------------
 fs/fuse/inode.c                       |   4 +-
 fs/gfs2/file.c                        |   2 +-
 fs/gfs2/glops.c                       |   2 +-
 fs/gfs2/inode.c                       |   4 +-
 fs/gfs2/ops_fstype.c                  |   2 +-
 fs/hfs/btree.c                        |   2 +-
 fs/hfs/inode.c                        |   2 +-
 fs/hfsplus/super.c                    |   2 +-
 fs/hostfs/hostfs_kern.c               |   2 +-
 fs/hpfs/dir.c                         |   2 +-
 fs/hpfs/inode.c                       |   2 +-
 fs/inode.c                            | 100 ++++++++++-----------
 fs/isofs/inode.c                      |   2 +-
 fs/jffs2/fs.c                         |   4 +-
 fs/jfs/file.c                         |   4 +-
 fs/jfs/inode.c                        |   2 +-
 fs/jfs/jfs_txnmgr.c                   |   2 +-
 fs/kernfs/inode.c                     |   2 +-
 fs/libfs.c                            |   6 +-
 fs/minix/inode.c                      |   2 +-
 fs/namei.c                            |   8 +-
 fs/netfs/misc.c                       |   8 +-
 fs/netfs/read_single.c                |   6 +-
 fs/nfs/inode.c                        |   2 +-
 fs/nfs/pnfs.c                         |   2 +-
 fs/nfsd/vfs.c                         |   2 +-
 fs/nilfs2/cpfile.c                    |   2 +-
 fs/nilfs2/dat.c                       |   2 +-
 fs/nilfs2/ifile.c                     |   2 +-
 fs/nilfs2/inode.c                     |  10 +--
 fs/nilfs2/sufile.c                    |   2 +-
 fs/notify/fsnotify.c                  |   2 +-
 fs/ntfs3/inode.c                      |   2 +-
 fs/ocfs2/dlmglue.c                    |   2 +-
 fs/ocfs2/inode.c                      |  10 +--
 fs/omfs/inode.c                       |   2 +-
 fs/openpromfs/inode.c                 |   2 +-
 fs/orangefs/inode.c                   |   2 +-
 fs/orangefs/orangefs-utils.c          |   6 +-
 fs/overlayfs/dir.c                    |   2 +-
 fs/overlayfs/inode.c                  |   6 +-
 fs/overlayfs/util.c                   |  10 +--
 fs/pipe.c                             |   2 +-
 fs/qnx4/inode.c                       |   2 +-
 fs/qnx6/inode.c                       |   2 +-
 fs/quota/dquot.c                      |   2 +-
 fs/romfs/super.c                      |   2 +-
 fs/smb/client/cifsfs.c                |   2 +-
 fs/smb/client/inode.c                 |  14 +--
 fs/squashfs/inode.c                   |   2 +-
 fs/sync.c                             |   2 +-
 fs/ubifs/file.c                       |   2 +-
 fs/ubifs/super.c                      |   2 +-
 fs/udf/inode.c                        |   2 +-
 fs/ufs/inode.c                        |   2 +-
 fs/xfs/scrub/common.c                 |   2 +-
 fs/xfs/scrub/inode_repair.c           |   2 +-
 fs/xfs/scrub/parent.c                 |   2 +-
 fs/xfs/xfs_bmap_util.c                |   2 +-
 fs/xfs/xfs_health.c                   |   4 +-
 fs/xfs/xfs_icache.c                   |   6 +-
 fs/xfs/xfs_inode.c                    |   6 +-
 fs/xfs/xfs_inode_item.c               |   4 +-
 fs/xfs/xfs_iops.c                     |   2 +-
 fs/xfs/xfs_reflink.h                  |   2 +-
 fs/zonefs/super.c                     |   4 +-
 include/linux/backing-dev.h           |   3 +-
 include/linux/fs.h                    |  42 ++++++++-
 include/linux/writeback.h             |   4 +-
 include/trace/events/writeback.h      |   8 +-
 mm/backing-dev.c                      |   2 +-
 security/landlock/fs.c                |   2 +-
 107 files changed, 342 insertions(+), 304 deletions(-)

-- 
2.43.0


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