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[46.135.89.171]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-43cf21e3602sm28792632f8f.4.2026.03.31.09.09.03 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 31 Mar 2026 09:09:04 -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, Mateusz Guzik Subject: [PATCH v5 1/4] fs: add icount_read_once() and stop open-coding ->i_count loads Date: Tue, 31 Mar 2026 18:08:48 +0200 Message-ID: <20260331160851.3854954-2-mjguzik@gmail.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260331160851.3854954-1-mjguzik@gmail.com> References: <20260331160851.3854954-1-mjguzik@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Similarly to inode_state_read_once(), it makes the caller spell out they acknowledge instability of the returned value. Signed-off-by: Mateusz Guzik --- arch/powerpc/platforms/cell/spufs/file.c | 2 +- fs/btrfs/inode.c | 2 +- fs/ceph/mds_client.c | 2 +- fs/ext4/ialloc.c | 4 ++-- fs/hpfs/inode.c | 2 +- fs/inode.c | 12 ++++++------ fs/nfs/inode.c | 4 ++-- fs/smb/client/inode.c | 2 +- fs/ubifs/super.c | 2 +- fs/xfs/xfs_inode.c | 2 +- fs/xfs/xfs_trace.h | 2 +- include/linux/fs.h | 13 +++++++++++++ include/trace/events/filelock.h | 2 +- security/landlock/fs.c | 2 +- 14 files changed, 33 insertions(+), 20 deletions(-) diff --git a/arch/powerpc/platforms/cell/spufs/file.c b/arch/powerpc/platfo= rms/cell/spufs/file.c index 10fa9b844fcc..f6de8c1169d5 100644 --- a/arch/powerpc/platforms/cell/spufs/file.c +++ b/arch/powerpc/platforms/cell/spufs/file.c @@ -1430,7 +1430,7 @@ static int spufs_mfc_open(struct inode *inode, struct= file *file) if (ctx->owner !=3D current->mm) return -EINVAL; =20 - if (icount_read(inode) !=3D 1) + if (icount_read_once(inode) !=3D 1) return -EBUSY; =20 mutex_lock(&ctx->mapping_lock); diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index 8d97a8ad3858..f36c49e83c04 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -4741,7 +4741,7 @@ static void btrfs_prune_dentries(struct btrfs_root *r= oot) =20 inode =3D btrfs_find_first_inode(root, min_ino); while (inode) { - if (icount_read(&inode->vfs_inode) > 1) + if (icount_read_once(&inode->vfs_inode) > 1) d_prune_aliases(&inode->vfs_inode); =20 min_ino =3D btrfs_ino(inode) + 1; diff --git a/fs/ceph/mds_client.c b/fs/ceph/mds_client.c index b1746273f186..2cb3c919d40d 100644 --- a/fs/ceph/mds_client.c +++ b/fs/ceph/mds_client.c @@ -2223,7 +2223,7 @@ static int trim_caps_cb(struct inode *inode, int mds,= void *arg) int count; dput(dentry); d_prune_aliases(inode); - count =3D icount_read(inode); + count =3D icount_read_once(inode); if (count =3D=3D 1) (*remaining)--; doutc(cl, "%p %llx.%llx cap %p pruned, count now %d\n", diff --git a/fs/ext4/ialloc.c b/fs/ext4/ialloc.c index 3fd8f0099852..8c80d5087516 100644 --- a/fs/ext4/ialloc.c +++ b/fs/ext4/ialloc.c @@ -252,10 +252,10 @@ void ext4_free_inode(handle_t *handle, struct inode *= inode) "nonexistent device\n", __func__, __LINE__); return; } - if (icount_read(inode) > 1) { + if (icount_read_once(inode) > 1) { ext4_msg(sb, KERN_ERR, "%s:%d: inode #%llu: count=3D%d", __func__, __LINE__, inode->i_ino, - icount_read(inode)); + icount_read_once(inode)); return; } if (inode->i_nlink) { diff --git a/fs/hpfs/inode.c b/fs/hpfs/inode.c index 0e932cc8be1b..1b4fcf760aad 100644 --- a/fs/hpfs/inode.c +++ b/fs/hpfs/inode.c @@ -184,7 +184,7 @@ void hpfs_write_inode(struct inode *i) struct hpfs_inode_info *hpfs_inode =3D hpfs_i(i); struct inode *parent; if (i->i_ino =3D=3D hpfs_sb(i->i_sb)->sb_root) return; - if (hpfs_inode->i_rddir_off && !icount_read(i)) { + if (hpfs_inode->i_rddir_off && !icount_read_once(i)) { if (*hpfs_inode->i_rddir_off) pr_err("write_inode: some position still there\n"); kfree(hpfs_inode->i_rddir_off); diff --git a/fs/inode.c b/fs/inode.c index 5ad169d51728..1f5a383ccf27 100644 --- a/fs/inode.c +++ b/fs/inode.c @@ -907,7 +907,7 @@ void evict_inodes(struct super_block *sb) again: spin_lock(&sb->s_inode_list_lock); list_for_each_entry(inode, &sb->s_inodes, i_sb_list) { - if (icount_read(inode)) + if (icount_read_once(inode)) continue; =20 spin_lock(&inode->i_lock); @@ -1926,7 +1926,7 @@ static void iput_final(struct inode *inode) int drop; =20 WARN_ON(inode_state_read(inode) & I_NEW); - VFS_BUG_ON_INODE(atomic_read(&inode->i_count) !=3D 0, inode); + VFS_BUG_ON_INODE(icount_read(inode) !=3D 0, inode); =20 if (op->drop_inode) drop =3D op->drop_inode(inode); @@ -1945,7 +1945,7 @@ static void iput_final(struct inode *inode) * Re-check ->i_count in case the ->drop_inode() hooks played games. * Note we only execute this if the verdict was to drop the inode. */ - VFS_BUG_ON_INODE(atomic_read(&inode->i_count) !=3D 0, inode); + VFS_BUG_ON_INODE(icount_read(inode) !=3D 0, inode); =20 if (drop) { inode_state_set(inode, I_FREEING); @@ -1989,7 +1989,7 @@ void iput(struct inode *inode) * equal to one, then two CPUs racing to further drop it can both * conclude it's fine. */ - VFS_BUG_ON_INODE(atomic_read(&inode->i_count) < 1, inode); + VFS_BUG_ON_INODE(icount_read_once(inode) < 1, inode); =20 if (atomic_add_unless(&inode->i_count, -1, 1)) return; @@ -2023,7 +2023,7 @@ EXPORT_SYMBOL(iput); void iput_not_last(struct inode *inode) { VFS_BUG_ON_INODE(inode_state_read_once(inode) & (I_FREEING | I_CLEAR), in= ode); - VFS_BUG_ON_INODE(atomic_read(&inode->i_count) < 2, inode); + VFS_BUG_ON_INODE(icount_read_once(inode) < 2, inode); =20 WARN_ON(atomic_sub_return(1, &inode->i_count) =3D=3D 0); } @@ -3046,7 +3046,7 @@ void dump_inode(struct inode *inode, const char *reas= on) } =20 state =3D inode_state_read_once(inode); - count =3D atomic_read(&inode->i_count); + count =3D icount_read_once(inode); =20 if (!sb || get_kernel_nofault(s_type, &sb->s_type) || !s_type || diff --git a/fs/nfs/inode.c b/fs/nfs/inode.c index 98a8f0de1199..22834eddd5b1 100644 --- a/fs/nfs/inode.c +++ b/fs/nfs/inode.c @@ -608,7 +608,7 @@ nfs_fhget(struct super_block *sb, struct nfs_fh *fh, st= ruct nfs_fattr *fattr) inode->i_sb->s_id, (unsigned long long)NFS_FILEID(inode), nfs_display_fhandle_hash(fh), - icount_read(inode)); + icount_read_once(inode)); =20 out: return inode; @@ -2261,7 +2261,7 @@ static int nfs_update_inode(struct inode *inode, stru= ct nfs_fattr *fattr) dfprintk(VFS, "NFS: %s(%s/%llu fh_crc=3D0x%08x ct=3D%d info=3D0x%llx)\n", __func__, inode->i_sb->s_id, inode->i_ino, nfs_display_fhandle_hash(NFS_FH(inode)), - icount_read(inode), fattr->valid); + icount_read_once(inode), fattr->valid); =20 if (!(fattr->valid & NFS_ATTR_FATTR_FILEID)) { /* Only a mounted-on-fileid? Just exit */ diff --git a/fs/smb/client/inode.c b/fs/smb/client/inode.c index 888f9e35f14b..ab35e35b16d7 100644 --- a/fs/smb/client/inode.c +++ b/fs/smb/client/inode.c @@ -2842,7 +2842,7 @@ int cifs_revalidate_dentry_attr(struct dentry *dentry) } =20 cifs_dbg(FYI, "Update attributes: %s inode 0x%p count %d dentry: 0x%p d_t= ime %ld jiffies %ld\n", - full_path, inode, icount_read(inode), + full_path, inode, icount_read_once(inode), dentry, cifs_get_time(dentry), jiffies); =20 again: diff --git a/fs/ubifs/super.c b/fs/ubifs/super.c index 9a77d8b64ffa..38972786817e 100644 --- a/fs/ubifs/super.c +++ b/fs/ubifs/super.c @@ -358,7 +358,7 @@ static void ubifs_evict_inode(struct inode *inode) goto out; =20 dbg_gen("inode %llu, mode %#x", inode->i_ino, (int)inode->i_mode); - ubifs_assert(c, !icount_read(inode)); + ubifs_assert(c, !icount_read_once(inode)); =20 truncate_inode_pages_final(&inode->i_data); =20 diff --git a/fs/xfs/xfs_inode.c b/fs/xfs/xfs_inode.c index beaa26ec62da..4f659eba6ae5 100644 --- a/fs/xfs/xfs_inode.c +++ b/fs/xfs/xfs_inode.c @@ -1046,7 +1046,7 @@ xfs_itruncate_extents_flags( int error =3D 0; =20 xfs_assert_ilocked(ip, XFS_ILOCK_EXCL); - if (icount_read(VFS_I(ip))) + if (icount_read_once(VFS_I(ip))) xfs_assert_ilocked(ip, XFS_IOLOCK_EXCL); if (whichfork =3D=3D XFS_DATA_FORK) ASSERT(new_size <=3D XFS_ISIZE(ip)); diff --git a/fs/xfs/xfs_trace.h b/fs/xfs/xfs_trace.h index 5e8190fe2be9..cbdec40826b3 100644 --- a/fs/xfs/xfs_trace.h +++ b/fs/xfs/xfs_trace.h @@ -1156,7 +1156,7 @@ DECLARE_EVENT_CLASS(xfs_iref_class, TP_fast_assign( __entry->dev =3D VFS_I(ip)->i_sb->s_dev; __entry->ino =3D ip->i_ino; - __entry->count =3D icount_read(VFS_I(ip)); + __entry->count =3D icount_read_once(VFS_I(ip)); __entry->pincount =3D atomic_read(&ip->i_pincount); __entry->iflags =3D ip->i_flags; __entry->caller_ip =3D caller_ip; diff --git a/include/linux/fs.h b/include/linux/fs.h index 8afbe2ef2686..07363fce4406 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -2225,8 +2225,21 @@ static inline void mark_inode_dirty_sync(struct inod= e *inode) __mark_inode_dirty(inode, I_DIRTY_SYNC); } =20 +/* + * returns the refcount on the inode. it can change arbitrarily. + */ +static inline int icount_read_once(const struct inode *inode) +{ + return atomic_read(&inode->i_count); +} + +/* + * returns the refcount on the inode. The lock guarantees no new references + * are added, but references can be dropped as long as the result is > 0. + */ static inline int icount_read(const struct inode *inode) { + lockdep_assert_held(&inode->i_lock); return atomic_read(&inode->i_count); } =20 diff --git a/include/trace/events/filelock.h b/include/trace/events/fileloc= k.h index 116774886244..c8c8847bb6f6 100644 --- a/include/trace/events/filelock.h +++ b/include/trace/events/filelock.h @@ -190,7 +190,7 @@ TRACE_EVENT(generic_add_lease, __entry->i_ino =3D inode->i_ino; __entry->wcount =3D atomic_read(&inode->i_writecount); __entry->rcount =3D atomic_read(&inode->i_readcount); - __entry->icount =3D icount_read(inode); + __entry->icount =3D icount_read_once(inode); __entry->owner =3D fl->c.flc_owner; __entry->flags =3D fl->c.flc_flags; __entry->type =3D fl->c.flc_type; diff --git a/security/landlock/fs.c b/security/landlock/fs.c index c1ecfe239032..32d560f12dbd 100644 --- a/security/landlock/fs.c +++ b/security/landlock/fs.c @@ -1278,7 +1278,7 @@ static void hook_sb_delete(struct super_block *const = sb) struct landlock_object *object; =20 /* Only handles referenced inodes. */ - if (!icount_read(inode)) + if (!icount_read_once(inode)) continue; =20 /* --=20 2.48.1