Merge patch series "vfs: change inode->i_ino from unsigned long to u64"

Jeff Layton <jlayton@kernel.org> says:

Christian said [1] to "just do it" when I proposed this, so here we are!

For historical reasons, the inode->i_ino field is an unsigned long,
which means that it's 32 bits on 32 bit architectures. This has caused a
number of filesystems to implement hacks to hash a 64-bit identifier
into a 32-bit field, and deprives us of a universal identifier field for
an inode.

This patchset changes the inode->i_ino field from an unsigned long to a
u64. This shouldn't make any material difference on 64-bit hosts, but
32-bit hosts will see struct inode grow by at least 4 bytes. This could
have effects on slabcache sizes and field alignment.

The bulk of the changes are to format strings and tracepoints, since the
kernel itself doesn't care that much about the i_ino field. The first
patch changes some vfs function arguments, so check that one out
carefully.

With this change, we may be able to shrink some inode structures. For
instance, struct nfs_inode has a fileid field that holds the 64-bit
inode number. With this set of changes, that field could be eliminated.
I'd rather leave that sort of cleanups for later just to keep this
simple.

[1]: https://lore.kernel.org/linux-fsdevel/20260219-portrait-winkt-959070cee42f@brauner/

* patches from https://patch.msgid.link/20260304-iino-u64-v3-0-2257ad83d372@kernel.org:
  treewide: change inode->i_ino from unsigned long to u64
  nilfs2: widen trace event i_ino fields to u64
  f2fs: widen trace event i_ino fields to u64
  ext4: widen trace event i_ino fields to u64
  zonefs: widen trace event i_ino fields to u64
  hugetlbfs: widen trace event i_ino fields to u64
  ext2: widen trace event i_ino fields to u64
  cachefiles: widen trace event i_ino fields to u64
  vfs: widen trace event i_ino fields to u64
  net: change sock.sk_ino and sock_i_ino() to u64
  audit: widen ino fields to u64
  vfs: widen inode hash/lookup functions to u64

Link: https://patch.msgid.link/20260304-iino-u64-v3-0-2257ad83d372@kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>

2 files changed, 24 insertions, 26 deletions

diff --git a/include/linux/audit.h b/include/linux/audit.h
index b642b5faca65..b915aaa7ed73 100644
--- a/include/linux/audit.h
+++ b/include/linux/audit.h
@@ -15,7 +15,7 @@
 #include <uapi/linux/audit.h>
 #include <uapi/linux/fanotify.h>
 
-#define AUDIT_INO_UNSET ((unsigned long)-1)
+#define AUDIT_INO_UNSET ((u64)-1)
 #define AUDIT_DEV_UNSET ((dev_t)-1)
 
 struct audit_sig_info {
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 8b3dd145b25e..e820c14f9c5a 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -783,7 +783,7 @@ struct inode {
 #endif
 
 	/* Stat data, not accessed from path walking */
-	unsigned long		i_ino;
+	u64			i_ino;
 	/*
 	 * Filesystems may only read i_nlink directly.  They shall use the
 	 * following functions for modification:
@@ -2934,33 +2934,31 @@ static inline int inode_generic_drop(struct inode *inode)
 }
 extern void d_mark_dontcache(struct inode *inode);
 
-extern struct inode *ilookup5_nowait(struct super_block *sb,
-		unsigned long hashval, int (*test)(struct inode *, void *),
-		void *data, bool *isnew);
-extern struct inode *ilookup5(struct super_block *sb, unsigned long hashval,
-		int (*test)(struct inode *, void *), void *data);
-extern struct inode *ilookup(struct super_block *sb, unsigned long ino);
-
-extern struct inode *inode_insert5(struct inode *inode, unsigned long hashval,
-		int (*test)(struct inode *, void *),
-		int (*set)(struct inode *, void *),
-		void *data);
-struct inode *iget5_locked(struct super_block *, unsigned long,
+struct inode *ilookup5_nowait(struct super_block *sb, u64 hashval,
+			      int (*test)(struct inode *, void *), void *data,
+			      bool *isnew);
+struct inode *ilookup5(struct super_block *sb, u64 hashval,
+		       int (*test)(struct inode *, void *), void *data);
+struct inode *ilookup(struct super_block *sb, u64 ino);
+
+struct inode *inode_insert5(struct inode *inode, u64 hashval,
+			    int (*test)(struct inode *, void *),
+			    int (*set)(struct inode *, void *), void *data);
+struct inode *iget5_locked(struct super_block *, u64,
 			   int (*test)(struct inode *, void *),
 			   int (*set)(struct inode *, void *), void *);
-struct inode *iget5_locked_rcu(struct super_block *, unsigned long,
+struct inode *iget5_locked_rcu(struct super_block *, u64,
 			       int (*test)(struct inode *, void *),
 			       int (*set)(struct inode *, void *), void *);
-extern struct inode * iget_locked(struct super_block *, unsigned long);
-extern struct inode *find_inode_nowait(struct super_block *,
-				       unsigned long,
-				       int (*match)(struct inode *,
-						    unsigned long, void *),
-				       void *data);
-extern struct inode *find_inode_rcu(struct super_block *, unsigned long,
-				    int (*)(struct inode *, void *), void *);
-extern struct inode *find_inode_by_ino_rcu(struct super_block *, unsigned long);
-extern int insert_inode_locked4(struct inode *, unsigned long, int (*test)(struct inode *, void *), void *);
+struct inode *iget_locked(struct super_block *, u64);
+struct inode *find_inode_nowait(struct super_block *, u64,
+				int (*match)(struct inode *, u64, void *),
+				void *data);
+struct inode *find_inode_rcu(struct super_block *, u64,
+			     int (*)(struct inode *, void *), void *);
+struct inode *find_inode_by_ino_rcu(struct super_block *, u64);
+int insert_inode_locked4(struct inode *, u64,
+			 int (*test)(struct inode *, void *), void *);
 extern int insert_inode_locked(struct inode *);
 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 extern void lockdep_annotate_inode_mutex_key(struct inode *inode);
@@ -3015,7 +3013,7 @@ int setattr_should_drop_sgid(struct mnt_idmap *idmap,
  */
 #define alloc_inode_sb(_sb, _cache, _gfp) kmem_cache_alloc_lru(_cache, &_sb->s_inode_lru, _gfp)
 
-extern void __insert_inode_hash(struct inode *, unsigned long hashval);
+void __insert_inode_hash(struct inode *, u64 hashval);
 static inline void insert_inode_hash(struct inode *inode)
 {
 	__insert_inode_hash(inode, inode->i_ino);