Merge patch series "hide ->i_state behind accessors"

Mateusz Guzik <mjguzik@gmail.com> says:

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).

In order to keep things manageable this patchset merely gets the thing
off the ground with only lockdep checks baked in.

Current consumers can be trivially converted.

Suppose flags I_A and I_B are to be handled.

If ->i_lock is held, then:

state = inode->i_state          => state = inode_state_read(inode)
inode->i_state |= (I_A | I_B)   => inode_state_set(inode, I_A | I_B)
inode->i_state &= ~(I_A | I_B)  => inode_state_clear(inode, I_A | I_B)
inode->i_state = I_A | I_B      => inode_state_assign(inode, I_A | I_B)

If ->i_lock is not held or only held conditionally:

state = inode->i_state          => state = inode_state_read_once(inode)
inode->i_state |= (I_A | I_B)   => inode_state_set_raw(inode, I_A | I_B)
inode->i_state &= ~(I_A | I_B)  => inode_state_clear_raw(inode, I_A | I_B)
inode->i_state = I_A | I_B      => inode_state_assign_raw(inode, I_A | I_B)

The "_once" vs "_raw" discrepancy stems from the read variant differing
by READ_ONCE as opposed to just lockdep checks.

Finally, if you want to atomically clear flags and set new ones, the
following:

state = inode->i_state;
state &= ~I_A;
state |= I_B;
inode->i_state = state;

turns into:

inode_state_replace(inode, I_A, I_B);

* patches from https://lore.kernel.org/20251009075929.1203950-1-mjguzik@gmail.com:
  fs: make plain ->i_state access fail to compile
  xfs: use the new ->i_state accessors
  nilfs2: use the new ->i_state accessors
  overlayfs: use the new ->i_state accessors
  gfs2: use the new ->i_state accessors
  f2fs: use the new ->i_state accessors
  smb: use the new ->i_state accessors
  ceph: use the new ->i_state accessors
  btrfs: use the new ->i_state accessors
  Manual conversion to use ->i_state accessors of all places not covered by coccinelle
  Coccinelle-based conversion to use ->i_state accessors
  fs: provide accessors for ->i_state
  fs: spell out fenced ->i_state accesses with explicit smp_wmb/smp_rmb
  fs: move wait_on_inode() from writeback.h to fs.h

Signed-off-by: Christian Brauner <brauner@kernel.org>

4 files changed, 5 insertions, 5 deletions

diff --git a/fs/gfs2/file.c b/fs/gfs2/file.c
index bc67fa058c84..ee92f5910ae1 100644
--- a/fs/gfs2/file.c
+++ b/fs/gfs2/file.c
@@ -744,7 +744,7 @@ static int gfs2_fsync(struct file *file, loff_t start, loff_t end,
 {
 	struct address_space *mapping = file->f_mapping;
 	struct inode *inode = mapping->host;
-	int sync_state = inode->i_state & I_DIRTY;
+	int sync_state = inode_state_read_once(inode) & I_DIRTY;
 	struct gfs2_inode *ip = GFS2_I(inode);
 	int ret = 0, ret1 = 0;
 
diff --git a/fs/gfs2/glops.c b/fs/gfs2/glops.c
index 0c0a80b3baca..c94e42b0c94d 100644
--- a/fs/gfs2/glops.c
+++ b/fs/gfs2/glops.c
@@ -394,7 +394,7 @@ static int gfs2_dinode_in(struct gfs2_inode *ip, const void *buf)
 	u16 height, depth;
 	umode_t mode = be32_to_cpu(str->di_mode);
 	struct inode *inode = &ip->i_inode;
-	bool is_new = inode->i_state & I_NEW;
+	bool is_new = inode_state_read_once(inode) & I_NEW;
 
 	if (unlikely(ip->i_no_addr != be64_to_cpu(str->di_num.no_addr))) {
 		gfs2_consist_inode(ip);
diff --git a/fs/gfs2/inode.c b/fs/gfs2/inode.c
index 8a7ed80d9f2d..890c87e3e365 100644
--- a/fs/gfs2/inode.c
+++ b/fs/gfs2/inode.c
@@ -127,7 +127,7 @@ struct inode *gfs2_inode_lookup(struct super_block *sb, unsigned int type,
 
 	ip = GFS2_I(inode);
 
-	if (inode->i_state & I_NEW) {
+	if (inode_state_read_once(inode) & I_NEW) {
 		struct gfs2_sbd *sdp = GFS2_SB(inode);
 		struct gfs2_glock *io_gl;
 		int extra_flags = 0;
@@ -924,7 +924,7 @@ fail_gunlock:
 	gfs2_dir_no_add(&da);
 	gfs2_glock_dq_uninit(&d_gh);
 	if (!IS_ERR_OR_NULL(inode)) {
-		if (inode->i_state & I_NEW)
+		if (inode_state_read_once(inode) & I_NEW)
 			iget_failed(inode);
 		else
 			iput(inode);
diff --git a/fs/gfs2/ops_fstype.c b/fs/gfs2/ops_fstype.c
index aa15183f9a16..889682f051ea 100644
--- a/fs/gfs2/ops_fstype.c
+++ b/fs/gfs2/ops_fstype.c
@@ -1751,7 +1751,7 @@ static void gfs2_evict_inodes(struct super_block *sb)
 	spin_lock(&sb->s_inode_list_lock);
 	list_for_each_entry(inode, &sb->s_inodes, i_sb_list) {
 		spin_lock(&inode->i_lock);
-		if ((inode->i_state & (I_FREEING|I_WILL_FREE|I_NEW)) &&
+		if ((inode_state_read(inode) & (I_FREEING | I_WILL_FREE | I_NEW)) &&
 		    !need_resched()) {
 			spin_unlock(&inode->i_lock);
 			continue;